Andres Jaimes

Instalando Debian Trixie y Sway

Mon, 25 May 2026 00:00:00 -0400

Llevo algún tiempo pensando en el sistema operativo que quiero para uso diario. He trabajado con sistemas que van desde Windows 3.1 a HPUX, pasando por OS9, OSX, Slackware y Ubuntu.

Cuando me inicié, disfrutaba de teclear comandos en DOS y de aplicaciones como alpine para leer el correo. Ese mundo simple donde aprendí y me desarrollé… y que ahora añoro.

Estoy cansado de las decenas de notificaciones que recibo diariamente y que solo me desconcentran de la tarea del momento. Cansado de los efectos de transparencia de OSX que no fueron pensados para mejorar la productividad. Cansado de ver como los sistemas cargan tantos programas inútiles que consumen la mayor parte de la memoria de mi ordenador haciéndome desear tener más… es justo lo que motiva ese círculo vicioso en el que vivimos, siempre deseando tener una computadora más nueva.

Cómo usar ripgrep (rg) en Linux o Mac

Wed, 25 Mar 2026 00:00:00 -0400

Este artículo contiene ejemplos de uso del comando ripgrep (rg).

ripgrep es un buscador de expresiones regulares rápido y moderno que busca recursivamente texto dentro de ficheros y que respeta automáticamente los ficheros .gitignore y omite directorios ocultos y binarios por defecto. El comando no viene preinstalado en la mayoría de los sistemas operativos, pero merece la pena aprenderlo.

Ejemplos de uso

Busca “hola” en el directorio actual:

1rg "hola"

Busca “hola” en el directorio “config”:

Instalando los controladores de nvidia en Debian Trixie

Mon, 16 Mar 2026 00:00:00 -0400

Importante: Sway no funciona con los controladores oficiales de nvidia. Fuente: Documentación de sway en el sitio de debian, actualizado al 15 de marzo de 2026.

Los usuarios de sway contamos con los controladores de código abierto de nouveou, pero, en ocasiones, necesitamos utilizar programas de inteligencia artificial (IA) que dependen de cuda para tener un mejor rendimiento. Dicha biblioteca requiere del controlador oficial de nvidia y, por ello, en este artículo describo como instalarla en Debian.

Cómo instalar Scala/Metals en MacOS

Sat, 14 Feb 2026 00:00:00 -0400

Utilizar Scala con Metals puede ser muy complicado si no se utilizan las versiones correctas. Después de muchas horas logré hacerlo funcionar y estoy encantado con su funcionamiento. Mi editor es Helix, pero los siguientes comandos funcionarán con cualquier otro editor.

Lo primero es desinstalar cualquier versión existente que tengamos de bloop o metals y, a continuación, instalar coursier y actualizar scala:

1brew install coursier
2brew upgrade scala

Ahora, utilizando coursier, instalamos bloop y metals:

Installing git and connecting to GitHub on FreeBSD or Linux

Thu, 29 Jan 2026 11:00:00 -0400

Git is a popular version control system that allows developers to manage their code repositories efficiently. If you are a developer using FreeBSD or Linux, you will need to set up Git and an authentication method to start collaborating on projects with other developers. In this post, we will walk you through the process of installing Git, creating SSH keys, and cloning a project from GitHub on FreeBSD or Linux.

Reading gmail email on macOS using fetchmail, postfix, sendmail, and alpine

Fri, 10 Oct 2025 13:00:00 -0400

This post describes the process for setting up macOS to read and store email locally –without deleting it from the remote server. The downloaded email can be read with a local application like Alpine.

The process goes like this:

fetchmail pulls emails from gmail
fetchmail hands the emails to postfix for local delivery
use alpine to read our locally delivered email
use alpine to write an email, which uses postfix to relay it via gmail
we can use sendmail for any other application that requires us to send emails

Configuring the hostname

From the Apple menu, open System Settings, and look for hostname. It should be under the Sharing settings.
Update the hostname to something that is easy to remember/type/etc. Mine, for example, is set to macos.local
Save the changes, open a terminal, and check the new name shows up with the following command:

1hostname

Allowing app access to gmail

Read this article.

Installing bash on macOS

Sun, 29 Jun 2025 12:05:00 -0400

A quick post on how to install bash on macOS to replace zsh.

Why did Apple stop shipping with bash? Licenses. The older version of Bash was licensed under GPLv2, while newer versions are licensed under GPLv3.

Installing bash

Run the following command to install bash:

1brew install bash
2/opt/homebrew/bin/bash --version

Add the newly installed shell to /etc/shells

1sudo vi /etc/shells

# List of acceptable shells for chpass(1).
# Ftpd will not allow users to connect who are not using
# one of these shells.

/bin/bash
/bin/csh
/bin/dash
/bin/ksh
/bin/sh
/bin/tcsh
/bin/zsh
/opt/homebrew/bin/bash

Run the following command to change the default shell:

Docker cheat-sheet

Sun, 29 Jun 2025 12:00:00 -0400

Posting some common docker commands:

docker compose up Starts services (add –build to force rebuild)
docker compose down Stops and removes everything (containers, networks)
docker compose stop Stops containers but does not remove them
docker compose start Restarts containers that were previously stopped
docker compose down -v Also removes named/anonymous volumes
docker compose down --rmi all Also removes images built by Compose

Creating C-API Interfaces for C++ code

Thu, 24 Apr 2025 12:00:00 -0400

At some point we’ll want our C++ code to interface with other languages, but since C is the standard, we have to find ways to adapt our C++ code to allow interaction via a C interface. A C API is a group of functions that allows other programs to call our C++ code using a well-known protocol. That means, we have to find ways to put our parameters and functions into a standard C wrapping so they can be used by other clients. By creating this interface, we can reuse our C++ code in multiple ways, for example, by creating dynamic libraries –dll’s, dylib’s or lib’s– and using them from different programs written in diverse languages.

Compiling Java and JavaFX applications into native binaries

Sun, 26 May 2024 10:00:00 -0400

This article will walk you through the process of compiling Java and JavaFX applications into native binaries using GraalVM and Gluon. This version is initially focused on MacOS, but will be updated for Windows.

Installing GraalVM

GraalVM is a software package that includes a Java SDK and tools for converting Java programs into native applications. I recommend you to use this SDK during your development. Let’s start by downloading GraalVM. The available Java version as of the publication of this page is 22. There are versions for both Intel and Apple processors.

Creating a simple static library

Wed, 12 Jul 2023 12:00:00 -0500

This article describes how to create a simple static library using C++. A static library is a collection of object files that are linked with and copied into a target application at compile time. The resulting executable contains all the object code from the static library, so it can be executed independently of the library.

Static library

Let’s start by creating a simple square class:

 1// src/square.h
 2#ifndef SQUARE_H
 3#define SQUARE_H
 4
 5class square {
 6private:
 7    double length;
 8public:
 9    square(double length);
10    double area();
11};
12
13#endif

and its corresponding implementation:

C++20 Modules

Tue, 11 Jul 2023 12:00:00 -0400

In this article, we’ll see how to create and use C++20 modules. We’ll use clang-16 to compile our code.

Prerequisites

OSX comes with clang-14 by default (2023). We can check its version with the following command:

1clang --version
2Apple clang version 14.0.3 (clang-1403.0.22.14.1)
3Target: arm64-apple-darwin22.5.0
4Thread model: posix
5InstalledDir: /Library/Developer/CommandLineTools/usr/bin

The latest version as of the time of this writing is clang-16. Use the following command to install it with homebrew:

Notes on C++

Fri, 16 Jun 2023 12:00:00 -0400

All the examples use C++17

Sort vector by property in class

In this example, we defined a class called open_order that has a long long open_time field, and a constructor.

To sort the vector of open_order objects based on the open_time field, we define a comparison function compare_by_open_time that compares two open_order objects based on their open_time values. The function returns true if the open_time of the first object is less than the open_time of the second object, which results in sorting the vector in ascending order of open_time.

Creating a simple dynamic library

Thu, 15 Jun 2023 12:00:00 -0500

This article describes how to create a simple shared library using C++. A shared library is a collection of object files that are linked with and loaded into a target application at runtime. The resulting executable contains only the object code that is needed to load the shared library, for this reason, the library has to be distributed with the executable.

Shared library

Let’s start by creating a simple sum.c program using C.

Online diff tool

Mon, 08 May 2023 12:00:00 -0400

This free online diff tool will help you compare two texts and highlight the differences between them. The whole process is done in your browser, so your texts are not sent to any server.

Paste the text you want to compare in the boxes below and click the Compare button.

diff

Press the Compare button

References

Resig, J. (n.d.). “Javascript Diff Algorithm.” Retrieved May 1, 2023, from https://johnresig.com/projects/javascript-diff-algorithm/

Create a bootable FreeBSD or Ubuntu USB flash drive on Mac/OS-X

Mon, 08 May 2023 09:00:00 -0400

This article provides step-by-step instructions on how to create a bootable USB flash drive for either FreeBSD or Ubuntu operating systems. The post includes the necessary commands to download and transfer the installation files onto the USB drive using the terminal on a macOS system. The author also includes a reference link for creating a FreeBSD installation memstick on macOS.

Download the files

Start by downloading the installation file for the operating system you want to install. For FreeBSD, you can download the amd64/memstick installation file from the FreeBSD website. For Ubuntu, you can download the desktop installation file from the Ubuntu website.

Common git commands

Tue, 02 May 2023 12:00:00 -0400

This page’s intention is to help me keep some git commands handy, since some times I forget how to do some tasks in the github workflow.

Our first step is to clone a repository using the command git clone git@github.com:some-account/some-project.git. Why use the git link instead of the http one? To avoid user authorization issues.

Once we’ve cloned the repository, we can start working on a new feature by creating a new branch using the git checkout command with the -b flag and a branch name, like this: git checkout -b my-feature. This creates a new branch called my-feature and switches to it. To see the list of branches, we can use the git branch command, and use git branch --show-current to see the current branch.

How to install Java and Maven on FreeBSD

Sat, 18 Mar 2023 10:00:00 -0400

FreeBSD is a powerful and reliable operating system that is widely used by developers and system administrators. If you are a Java developer, you will need to install both Java and Maven on your FreeBSD system to build and run your Java applications. In this post, we will walk you through the steps to install Java and Maven on FreeBSD.

Java

We will start by switching to the root account, and installing java. The flavor to use is openjdk.

How to install postgres on FreeBSD

Sat, 18 Mar 2023 09:00:00 -0400

PostgreSQL, also known as Postgres, is a popular open-source relational database management system (RDBMS) that is widely used by developers and organizations around the world. FreeBSD, a free and open-source operating system, is well-known for its reliability, performance, and security features. In this blog post, we will guide you through the process of installing PostgreSQL in FreeBSD. Whether you’re a developer or a system administrator, this step-by-step tutorial will help you get started with it.

Online JSON validator and formatter

Tue, 14 Mar 2023 09:00:00 -0400

Welcome to our online JSON validator, a tool for validating and formatting JSON code. JSON (JavaScript Object Notation) is a widely used format for storing and exchanging data on the web. Our validator helps you check that your JSON code is correctly formatted, and error-free. Whether you’re a developer or just starting with JSON, our tool will make your work easier and more efficient. Simply copy and paste your JSON code into the input field, and let our validator do the rest.

APA citation formatter for online resources

Sun, 12 Mar 2023 09:00:00 -0400

The APA citation style is a widely-used academic citation format developed by the American Psychological Association. It provides guidelines for citing sources in written works, such as research papers, essays, and academic publications. The style includes specific formatting and citation rules for various types of sources, including books, articles, websites, and more. The main goal of the APA citation style is to ensure accuracy and clarity in citing sources, while also providing a standard format for referencing that allows readers to easily locate and verify the sources used in a written work.

Setting up node and typescript

Sat, 01 Oct 2022 10:16:12 -0500

This article describes the creation process of a node application with TypeScript.

Installing nvm

There are multiple ways to install node but we have picked the nvm path. This method will allow us to have multiple versions of node installed on the computer.

We have to make sure that xcode command line tools are installed. We can trigger the installation by trying a command like cc on the terminal.

Run the following command to install nvm:

Microservices Design and Best Practices

Thu, 25 Aug 2022 21:11:52 -0500

Some of my notes and best practices learned over the years designing and developing microservices.

UI

Thin layer. Do not add any business logic to this layer.
Contains React code and may contain web assets.
Has a shared look and feel that provides a visual consistency to the project.
It is a web application, like Play, to allow us to set and remove cookies and delegate calls to the proxy.
It can be simpler to share data among react components.
It does not handle sessions so it can be part of a distributed system.
May be part of a larger web application, like a portal.
CSS can be shared across the application, achieving consistency in a simpler way.
It is stateless.
It is deployed independently of other components and services.
It can be configured locally along with a proxy to set up fake requests during development. This way front-end developers do not have to wait for back-end developers to complete their work.

The following are some issues that may come up when we split the UI in multiple subprojects:

Calling a DLL from MQL

Mon, 25 Apr 2022 18:03:22 -0400

There are times when we want access to additional data structures and function libraries than the ones provided by MetaTrader’s MQL. Besides native open-source MQL options, we can create our own Dynamic Link Library (DLL) in C# or C++ and link it to our programs.

In this article, we research how to connect to DLLs created with these languages. We must keep in mind that the code generated by C# is managed code running on the .NET framework, while C++’s code is native. We are going to use Visual Studio 2022 for this exercise.

Parsing Json with the Play Framework

Mon, 03 Jan 2022 10:16:12 -0500

This article discusses different common scenarios for JSON parsing and conversion, useful when working with the Play Framework library. All the examples in the article, use one or more of the following library imports:

1import play.api.libs.functional.syntax._
2import play.api.libs.json.{Format, JsError, JsNull, JsPath, JsResult, JsString, JsSuccess, JsValue, Json, OFormat, Reads}

The first import is required to use the special and and or functions found through the examples below.

JSON that matches property names

The first snippet allows us to parse different basic data types from a json-formatted input. The following json:

Scala Lectures

Mon, 06 Dec 2021 14:52:48 -0500

A curated list of Scala lectures on functional programming and design patterns.

Functional programming design patterns

Wlaschin, Scott. “Functional programming design patterns.” 30 Aug 2015, youtu.be/E8I19uA-wGY

In object-oriented development, we are all familiar with design patterns such as the Strategy pattern and Decorator pattern, and design principles such as SOLID. The functional programming community has design patterns and principles as well. This talk will provide an overview of some of these, and present some demonstrations of FP design in practice.

Using Cats Effect IO with the Play Framework

Tue, 30 Nov 2021 19:49:08 -0500

Cats Effect IO operations have to be performed at the highest level possible. So when working with the Play Framework the solution is to execute unsafeToFuture() in the controller methods.

1def get = Action.async { implicit request =>
2  service.get().map { items =>
3    Ok(Json.toJson(items))
4  }.unsafeToFuture()
5}

We can as well write an Action implementation that automatically calls unsafeToFuture:

 1object IOHttp {
 2
 3  implicit class ActionBuilderOps[+R[_], B](ab: ActionBuilder[R, B]) {
 4
 5    import cats.effect.implicits._
 6
 7    def asyncF[F[_] : Effect](cb: R[B] => F[Result]): Action[B] = ab.async { c =>
 8      cb(c).toIO.unsafeToFuture()
 9    }
10  }
11}

And then use it like this:

Cats Effect IO - Retry with backoff pattern

Tue, 30 Nov 2021 19:46:15 -0500

Scala example for using the retry-with-backoff pattern with Cats Effect IO.

Quick notes on functors

Tue, 30 Nov 2021 19:32:27 -0500

Functors

A functor is a design pattern that allows us to apply a function to a contextualized (wrapped) type. This is accomplished by implementing the map function:

1fmap :: (a -> b) -> f a -> f b

Notes on lazy evaluation

Tue, 30 Nov 2021 19:03:46 -0500

Lazy evaluation is a strategy that delays expression evaluation until their value is needed. It also avoids repeated evaluations by returning previously computed results by storing them in a lookup table.

Why isn’t lazy evaluation used everywhere?

Lazy evaluations are not used everywhere (not used in every software currently produced) because of the following reasons:

Lazy evaluation requires book-keeping overhead - you have to know if it’s been evaluated yet and such things. Eager evaluation is always evaluated, so you don’t have to know. This is especially true in concurrent contexts.
Secondly, it’s trivial to convert eager evaluation into lazy evaluation by packaging it into a function object to be called later, if you so wish.
Thirdly, lazy evaluation implies a loss of control. What if I lazily evaluated reading a file from a disk? Or getting the time? That’s not acceptable.

We observe from the examples on the third bullet that lazy evaluation and side effects do not play well together. For example, a file could be modified by an external process and we might need to read the latest update.

Future Either

Fri, 08 Oct 2021 12:00:00 -0400

This implementation is based on the work of Malcolm, and exists because it provides the cleanest use of similar monads.

The base monad wraps an Either class in a Future class:

 1import scala.concurrent.{ExecutionContext, Future}
 2import scala.util.{Failure, Success, Try}
 3
 4final case class FutureEither[+E, +A](value: Future[Either[E, A]]) {
 5
 6  def map[B](f: A => B)(implicit ec: ExecutionContext): FutureEither[E, B] =
 7    FutureEither(value map {
 8      case Right(a) => Right(f(a))
 9      case Left(e) => Left(e)
10    })
11
12  def flatMap[EE >: E, B](f: A => FutureEither[EE, B])(implicit ec: ExecutionContext): FutureEither[EE, B] =
13    FutureEither(value flatMap {
14      case Right(a) => f(a).value.map {
15        case Right(a) => Right(a)
16        case Left(e) => Left(e)
17      }
18      case Left(e) => Future.successful(Left(e))
19    })
20
21}

The companion object defines multiple functions to instantiate a FutureEither from other monads.

Generate a random string using the console

Mon, 27 Sep 2021 15:47:13 -0400

Generate a random string using the command line:

1cat /dev/urandom | tr -cd [:graph:] | head -c 32

On OSX, the previous command might return a tr: Illegal byte sequence error, so try:

1export LC_ALL=C; cat /dev/urandom | tr -cd [:graph:] | head -c 32

AES Encryption with Base64 encoding

Sun, 25 Jul 2021 21:11:52 -0500

We start by adding our imports.

1import java.nio.charset.StandardCharsets
2import java.security.Key
3import java.util.Base64
4import javax.crypto.Cipher
5import javax.crypto.spec.SecretKeySpec

For this example we’re going to use the CBC (Cipher Block Chaining) variation of AES.

1val Algorithm: String = "AES"
2val Transformation: String = "AES/ECB/PKCS5Padding"
3
4def aeskey: String => Key = key =>
5  new SecretKeySpec(key.getBytes, Algorithm)

Our encrypt function receives a key and some text to encrypt. The function will return a base64-encoded string if everything goes ok.

How to Set Up DynamoDB for Local Development

Thu, 08 Jul 2021 18:21:53 -0400

In this article we are going to set up dynamodb on our local development environment. A short description of a couple of easy-to-use management tools is included.

DynamoDB

Start by downloading the DynamoDB development version. Uncompress the file and create a launch script with the following contents:

1#!/bin/sh
2
3java -Djava.library.path=./DynamoDBLocal_lib -jar DynamoDBLocal.jar -sharedDb -port 8000

The script will launch dynamo on port 8000 and will create a file called shared-local-instance.db on the current directory when the first table is added. Add execution permissions to the script we just created:

Monoid definition and examples

Fri, 30 Apr 2021 17:13:03 -0400

We are going to cite the definition of a Monoid found on this post:

Conceptually, a monoid is anything that:

- Has a "zero-value": `mempty`, e.g., `0`
- Can be "appended" together: `mappend`, e.g., `+`
- Has an identity with the zero-value: `x + 0 == x, 0 + x == x`
- Is associative: `x + y + z == (x + y) + z == x + (y + z)`

This isn’t limited to just arithmetic with operators like +. You can define whole new types as monoids if they have these characteristics. For example, we can merge together configuration files by using monoid operators (in pseudo-code):

Creating an sbt project from scratch

Sun, 25 Apr 2021 13:12:19 -0400

Files and project structure

sbt projects use the same structure as Maven. Creating a project from scratch involve the following steps:

1mkdir some-new-project
2cd some-new-project
3mkdir -p src/{main,test}/{resources,scala}
4mkdir project

Create a new file called build.sbt and add the following contents:

name := "SomeNewProject"
version := "1.0"
scalaVersion := "2.13.5"

Our final folder structure has to look like this:

Sending a message using telegram and scala

Thu, 11 Feb 2021 19:11:59 -0500

In this article we are going to use scala to send a message via Telegram. The process is very simple and pretty much involves setting up a bot and making a GET request to Telegram’s api.

The Telegram app on the phone has more features than its desktop counterpart. I recommend you to use the phone version to make sure you have access to all the required features.

On Telegram

1. Create a Telegram public channel

Telegram requires you to have a public channel to be able to publish messages using a bot.

How to create a self-contained jar file (fat jar) using sbt

Sat, 06 Feb 2021 10:39:48 -0500

A fat jar is a jar file that contains any dependencies required by a Java or Scala program. Deployment becomes an easy task if we only have to deal with one single file. In this article we’ll go through the steps required to create a fat jar using Scala and sbt.

The following procedure has been tested using Scala 2.12.8, sbt 1.2.8 and jdk 11.

1. project/assembly.sbt

Create project/assembly.sbt and add the following line:

Add your GMail account to MetaTrader Notifications

Fri, 15 Jan 2021 12:49:53 -0500

On this article we’re going to set up Metatrader for email sending. This is recommended so you don’t miss important messages happening to your account.

Getting a password from Google

If you want to connect your Google email account, you have to generate a new password for Metatrader. To generate a Google password:

On the GMail page click on the Apps menu at the top right corner and then click on Account.

Implementing put and delete operations using BatchWriteItem

Tue, 17 Nov 2020 10:57:37 -0500

The BatchWriteItem operation allows us to work with groups of up to 25 items per request. Additionally, we can put and delete items to one or multiple tables. Amazon DynamoDB’s page says:

A single call to BatchWriteItem can write up to 16 MB of data, which can comprise as many as 25 put or delete requests. Individual items to be written can be as large as 400 KB.

In this article we are going to go through the process of putting and deleting items to a table that looks like this:

Undoing the Last Git Commit

Thu, 22 Oct 2020 18:34:09 -0400

A command so important, it deserves its own page:

1git reset --soft HEAD~1

The previous command undoes the last commit to git. I think this is one of those commands that I have typed many times during the last year. It’s very important to know which branch we currently are on, but sometimes excitement (or stress) may make us forget checking it.

If this is not enough, then we can reset our branch to master like this: (this will lose all our changes):

Inserting and updating items to DynamoDB lists and maps

Sun, 04 Oct 2020 11:25:10 -0400

Should I use a map or a list? A simple rule:

If you need to update or remove an item, lists only allow you to do it by index. While maps let you do it by key.

Their simplified representation goes like this:

1{
2  "someMap": {
3    "key1": "value1",
4    "key2": "value2",
5  },
6  "someList": ["value1", "value2"]
7}

Inserting and updating to a map

The following example adds or updates an instance of “SomeItem” as a json string into a map field called someMapField. A sample simplified record looks like this:

Testing scala classes and controllers

Sun, 04 Oct 2020 00:41:51 -0400

This article discusses different approaches for testing classes, services, and PlayFramework controllers using scalatest.

Setting up the project dependencies

First step is to add to build.sbt the next dependency:

1"org.scalatest" %% "scalatest" % "3.2.2"

The following template unit test uses the WordSpec style which offers a natural way for writing tests. scalatest offers more styles, but I find this one more expressive.

PlaySpec (found in the PaylFramework) extends WordSpec and has a similar behavior.

Enumerations

Mon, 28 Sep 2020 10:25:05 -0400

Using case object

Unlike other languages, Scala does not have a keyword for enumerations. One way to implement them is by using case objects. For example:

1sealed trait OperatingSystem extends Product with Serializable
2
3object OperatingSystem {
4  case object FreeBsd extends OperatingSystem
5  case object Debian extends OperatingSystem
6  case object Alpine extends OperatingSystem
7  case object Arch extends OperatingSystem
8  case object Osx extends OperatingSystem
9}

To use it, just define a value of type OperatingSystem. You can even get a string representation from these values:

Installing Rancher on Ubuntu/Docker

Sun, 23 Aug 2020 18:30:02 -0400

On this article we are going to install a rancher server on Ubuntu. Let’s start by getting the rancher image from docker hub:

1sudo docker run -d --restart=always -p 8080:8080 --name=rancher-server rancher/server

Go to http://ip-address:8080 and click on Add Host. It is important that you do not use a localhost address (127.0.0.1, localhost). If you do so, and you want to add your local computer as an agent, you will not be able to reach it.

From MySQL to Postgres - Useful commands

Mon, 17 Aug 2020 18:43:47 -0400

This article shows a list of basic commands on MySQL and their corresponding versions for PostgreSQL.

Connecting to a database

MySQL

1$ mysql -u root -p

Postgres

1$ psql -h <host> -U <username> <database-name>

Try the following if you don’t know the name of the available databases:

1psql -h <host> -U <username> -l

Some installations add your current user to the list of allowed users to the database. In that case you can connect without specifying a username. Some others create a postgres or pgsql user, so as an alternative, you can su into that user and then run psql:

Ideas for successful software projects

Mon, 17 Aug 2020 16:31:02 -0400

This article describes some ideas on getting a successful software development process.

A successful project:

Depends on the expertise of the team. Don’t try to push many new technologies into a project. It will be difficult for the team to get acquainted with them and deliver a good quality project. Small steps are the best.
Depends on the level of communication among the participants. Enforce communication among the team members. Even if they are working remotely. Make sure they have the right tools for chatting and video conferencing.
Depends on the degree of delegation to take decisions. Don’t try to guess what your customers want. It’s very likely customers have a pretty clear idea of what they’re expecting. Involve them. Let them participate in the process.
Depends on whether they have direct contact with the customer or not. Let your developers ask questions to the project shareholders. It will give them a clearer idea of what the customer is looking for.
Depends on whether the project has been planned or not. Document ideas, meetings, mock-ups. Create links and make them available to everyone in the project. Create a document of requirements and keep it updated.

Things that may affect the process or its final result:

Storing MySQL credentials on a file

Mon, 17 Aug 2020 15:12:47 -0400

MySQL allows you to store credentials in a file called ~/.my.cnf. The contents can look like this:

[mysqldump]
user=myuser
password=mypassword

We have to modify the file permissions and give read/write permissions to the owner only:

1chmod 600 ~/.my.cnf

And done. We can now use it:

1mysqldump mydatabase

mysqldump is going to read the credentials from that file.

Why you should not initialize a random generator with a static number

Mon, 17 Aug 2020 14:05:18 -0400

The following examples use random generated numbers initialized with a static seed. Never do it like this.

Run the following examples multiple times to understand why it is important to have a good seed.

PHP version:

1#!/usr/bin/php
2
3<?php
4srand(2);
5
6echo rand(0,10)."\n";
7echo rand(0,5)."\n";
8echo rand(0,4)."\n";
9echo rand(0,6)."\n";

Java version:

Common tasks when working with MySQL

Mon, 17 Aug 2020 13:24:20 -0400

How to install MySQL server in Ubuntu

It’s pretty simple:

1sudo apt-get install mysql-server

How to connect to MySQL using Java

This is a useful and simple snippet:

 1import java.sql.Connection;
 2import java.sql.DriverManager;
 3public class Test {
 4    public static void main(String[] args) {
 5        try {
 6            Class.forName("com.mysql.jdbc.Driver");
 7            Connection c = DriverManager.getConnection(
 8              "jdbc:mysql://localhost/?user=root&password=");
 9            c.close();
10            System.out.println("Success");
11        }
12        catch (Exception e) {
13            e.printStackTrace();
14        }
15    }
16}

How to connect to MySQL using C#

Go to http://www.mysql.com and download the .NET connector. I used the “no installation” zip file. Uncompress it. In C# go to Project > Add Reference > Browse and select the file named MySql.Data.dll located in the bin directory of the zip file you just uncompressed. Press Ok.

Akka Actors

Mon, 17 Aug 2020 08:40:41 -0400

The Play Framework is built upon Akka actors, but does everything so that you don’t really need to use them. Despite this, actors are easy to integrate with Play, precisely because it is built on them (there is already an actor system for you to use)

A few exceptions are:

websockets handling (doing that using actors is a breeze)
scheduling tasks for doing daily or weekly jobs

Akka actors use messages to communicate between among them. This behavior allows callers to send a message and go back to the pool of available threads to keep processing more requests.

Inspirational videos

Mon, 17 Aug 2020 08:25:28 -0400

This article contains a series of curated inspirational videos from different users.

“It will make you rich”. What poor people don’t know about making money

Videos from UKspreadbetting

Mon, 17 Aug 2020 08:24:55 -0400

This article contains a series of inspirational videos from user UKspreadbetting which I consider very important.

Why trading forex is so difficult

Is trading the road to great rewards and richness?

Trade entries and exits

Institutional traders versus private traders

Recommended libraries for Java

Sun, 02 Aug 2020 11:20:17 -0400

This article lists a curated list of Java libraries that I have used over the years for different projects. They are all well documented, and for most of them, plenty of examples can be found on the web.

Apache Commons Email

Commons Email

Commons Email aims to provide a API for sending email. It is built on top of the Java Mail API, which it aims to simplify.

User Guide

Apache Commons StringUtils

1<dependency>
2    <groupId>org.apache.commons</groupId>
3    <artifactId>commons-lang3</artifactId>
4    <version>3.4</version>
5</dependency>

1    StringUtils.isBlank(null)      = true;
2    StringUtils.isBlank("")        = true; 
3    StringUtils.isBlank(" ")       = true; 
4    StringUtils.isBlank("bob")     = false; 
5    StringUtils.isBlank("  bob  ") = false;

Apache OpenNLP

Check multiple option values in Scala

Fri, 31 Jul 2020 22:42:42 -0400

Two main approaches for doing this, the second one being for me the most appropriate.

Check values using regular if conditions:

1if (opt1.isDefined && opt2.isDefined && opt3.isDefined) // do something

Check values using match:

1(opt1, opt2, opt3) match {
2  case(Some(val1), Some(val2), Some(val3)) => ???
3  case _ => ???
4}

Creating and validating JWT JSON web tokens

Thu, 30 Jul 2020 19:57:40 -0400

This article goes through the process of creating and validating JWT’s (JSON web tokens) using Scala.

Our implementation uses the awesome io.jsonwebtoken library, and can be added to a sbt project like this:

1libraryDependencies ++= Seq("io.jsonwebtoken" % "jjwt" % "0.9.1")

Creating a token

We are going to use Scala’s apply/unapply functions for this implementation. This will allow us to use matchers for checking JWT’s.

 1import java.time.Instant
 2import java.util.{Date, UUID}
 3
 4import io.jsonwebtoken.{Claims, Jws, Jwts, SignatureAlgorithm}
 5
 6import scala.collection.JavaConverters._
 7
 8object Jwt {
 9
10  val Ttl: Int = 3600
11  val Secret: String = "MySecret"
12
13  def apply(claims: Map[String, Any]): String = {
14    val jwt = Jwts.builder()
15      .setId(UUID.randomUUID.toString)
16      .setIssuedAt(Date.from(Instant.now()))
17      .setExpiration(Date.from(Instant.now().plusSeconds(Ttl)))
18      .signWith(SignatureAlgorithm.HS512, Secret.getBytes("UTF-8"))
19    
20    claims.foreach { case (name, value) =>
21      jwt.claim(name, value)
22    }
23    
24    jwt.compact()
25  }

Ideally Ttl and Secret should be provided by a configuration object. Such an object can be passed as an implicit parameter to this function.

Make a request to a remote service

Thu, 30 Jul 2020 16:37:00 -0400

This article shows how to make remote requests to services using Scala and the Play-Framework. It documents some recommended features that can improve the reliability of the request.

Setup

Make sure you add the following dependency to build.sbt

libraryDependencies += ws

GET request

GET request to a remote service

 1import scala.concurrent.Future
 2import play.api.http.Status._
 3import play.api.libs.ws.WSClient
 4import play.api.libs.json.{JsSuccess, Json}
 5
 6case class UnexpectedResponseStatus(message: String) extends Exception(message)
 7case class InvalidServiceResponse(message: String) extends Exception(message)
 8
 9class SomeClass @Inject()(
10  ws: WSClient
11) {
12  def getFromRemoteService(url: String): Future[Option[MyClass]] = {
13    ws.url(url).get map { response =>
14      response.status match {
15        case OK => response.status match {
16          response.json.validate[MyClass] match {
17            case success: JsSuccess[MyClass] => Some(success.get)
18            case _ => throw InvalidServiceResponse("Invalid response, expecting MyClass response.")
19          }
20        case BAD_REQUEST => ??? // do something
21        case NOT_FOUND => None
22        case _ => throw UnexpectedResponseStatus(s"Service response status: ${response.status}")
23      }
24    } recoverWith { case e: Exception =>
25      logger.error(s"Remote request failed: ${e.getMessage}", e)
26      Future.failed(e)
27    }
28  }
29}

POST, PUT, PATCH, DELETE requests

All other requests types can be implemented this way.

Migrating from WordPress to Hugo

Tue, 28 Jul 2020 10:02:58 -0400

The idea behind migrating to hugo is to avoid having to deal with server and certificate updates, backups and so on. Plus moving a site to a global network, like Netlify’s, comes with the added benefits of quick download speeds and an easy to use deployment process.

Migration steps

Install the WordPress to hugo Exporter plugin to your WordPress site.

This plugin does not have any configuration settings. You just have to export it.

Meet the $250,000,000 man

Mon, 27 Apr 2020 15:51:40 +0000

When you do have money, the money gives you power… because you don’t have to answer to anybody. - Ben Mallah

Who pays wages?

Sun, 26 Apr 2020 22:28:56 +0000

It is not the employer who pays the wages. Employers only handle the money. It is the customer who pays the wages. - Henry Ford

Error handling for JS fetch requests

Sun, 26 Apr 2020 19:31:39 +0000

The following example handles server and connectivity errors for javascript fetch requests.

 1function handleErrors(response) {
 2    if (!response.ok) throw new Error(response.status)
 3    return response
 4}
 5
 6fetch('https://jsonplaceholder.typicode.com/todos/1')
 7    // handle network err/success
 8    .then(handleErrors)
 9    // use response of network on fetch Promise resolve
10    .then(response => console.log("ok"))
11    // handle fetch Promise error
12    .catch(error => console.log('found an error: ', error))

handleErrors can be updated for handling different types of errors in different ways. This function is called whenever we get a response from the server (successful or failed). When we have a different type of error, like a DNS one, the catch block is called directly.

A purely functional example using Scala

Tue, 27 Aug 2019 22:49:14 +0000

On this tutorial we’re going to explore the basics of purely functional programming using Scala. One of the principles with purely functional style, is that we have to define concepts in terms of functions.

The basics: Comparing a number

We’re going to create a simple function that lets us compare a number to a previously stored number in a purely functional way. For that, we can define the following function:

Examples of ‘for’ queries with Scala

Sat, 24 Aug 2019 21:47:00 +0000

On this page you are going to find some examples of ‘for’ queries.
Let’s start by defining the following database:

 1case class Book(title: String, authors: List[String])
 2
 3val books: List[Book] = List(
 4  Book("structure and interpretation of computer programs",
 5      List("abelson, harald", "sussman, gerald j.")),
 6  Book("introduction to functional programming",
 7    List("bird, richard", "wadler, phil")),
 8  Book("effective java",
 9    List("bloch, joshua")),
10  Book("java puzzlers",
11    List("bloch, joshua", "gafter, neal")),
12  Book("programming in scala",
13    List("odersky, martin", "spoon, lex", "venners, bill"))
14)

Find the titles of books whose author’s name is ‘bird’

Enterprise Architect – Synchronize model from a live database

Mon, 12 Nov 2018 17:18:28 +0000

Synchronize a model from a live database to Enterprise Architect.

Select your database from the Database Model folder in Project Browser.
Go to Tools > Database Builder
Right click on Tables > Show Differences. We can also click on a different type of object.
a. An active connection is needed to complete the previous step. If no one exists Enterprise Architect will ask us to create one.
The list of differences will show up on the Database Compare tab
Select the ones you want to import or click the Set Import All button.
The list of updates to perform will show up at the bottom of the page.
Press Import from ODBC to start the process. There’s no visual feedback other than the UI becoming irresponsive during the process. Be patient.

Running Pentaho Data Integration on Mac OSX

Fri, 09 Nov 2018 14:54:28 +0000

Run Pentaho Data Integration on Mac OSX. The following procedure works with all the latest OSX versions.

My local configuration

OSX Mojave
OpenJDK 11

Procedure

Download pdi-ce-8.1.0.0-365.zip from https://sourceforge.net/projects/pentaho/
Unzip it
Using the terminal, cd into the unzipped directory
Run the application open Data\ Integration.app

If you get the following error:

LSOpenURLsWithRole() failed with error -10810 for the file Data Integration.app

then run the following command (it is permissions related):

PlayFramework – Java

Wed, 11 Jul 2018 22:45:08 +0000

So far I have really liked this concept. The only con is that some times is difficult to find full examples that use the latest version.

Installing sbt

We need sbt for compiling and running Play applications.

brew install sbt@1

Executing a first application

Check the tutorials page to see how to create a first project.

Pretty much:

sbt new playframework/play-java-seed.g8
sbt run

And then visit localhost:9000

Play 2.6 throws the following exception unless an additional dependency is added:

Password Requirements Validation with JQuery

Wed, 30 May 2018 20:52:01 +0000

Password forms are challenging for users because we often ask them to enter complex strings which they are usually not allowed to see. Additionally, these strings have to meet different criteria – like having upper and lower case characters, numbers and so on – to keep our applications secure.

In this post, we are going to add visual queues to a form that will allow users to get a better experience with passwords.

How to run a custom update using Java JPA

Tue, 15 May 2018 19:14:36 +0000

From time to time it is necessary to execute a query without using Java’s JPA infrastructure.

In order to do it, we have to define a NamedQuery to execute. In this example, I will run an update against the database.

@Entity
@NamedQueries ({
    @NamedQuery (
        name = "SomeEntity.TestQuery",
        query = "update SomeEntity se set se.myField = '' where se.id = 0"
    )
})
public class SomeEntity implements Serializable {
    // ...
    private String myField;
    // ...
}

As you can see, the custom query does not use the database table name, but the JPA one. This is usually the name of the class that we have declared as Entity. In this case it is called SomeEntity.

Quick lessons on working with Java’s BigDecimal

Sun, 13 May 2018 23:26:21 +0000

Today I bring an example of the different results you can expect when using Java’s BigDecimal class. From instantiation to applying different arithmetic operations, it is important to understand how they affect the resulting instances.

The following program shows different scenarios and results applied to BigDecimal’s.

 1package test;
 2
 3import java.math.BigDecimal;
 4import java.math.RoundingMode;
 5
 6public class Test {
 7
 8    public static void main(String[] args) {
 9        BigDecimal a = new BigDecimal("1.204165");
10        System.out.println("a (from string): " + a);
11        // 1.204165
12        
13        a = new BigDecimal(1);
14        System.out.println("a (from int): " + a);
15        // 1
16        
17        a = new BigDecimal(1.204165);
18        System.out.println("a (from float): " + a);
19        // 1.2041649999999999298694319804781116545200347900390625
20        
21        a = a.setScale(6, RoundingMode.HALF_UP);
22        System.out.println("a (setting scale): " + a);
23        // 1.204165
24        
25        System.out.println("Add (1): " + a.add(new BigDecimal("0.0001")));
26        // 1.204265
27        
28        System.out.println("Add (2): " + a.add(new BigDecimal(0.0001)));
29        // 1.204265000000000000004792173602385929598312941379845142364501953125
30        
31        System.out.println("Add (3): " + a.add(new BigDecimal(0.0001).setScale(6, RoundingMode.HALF_UP)));
32        // 1.204265
33        
34        System.out.println("Sub (1): " + a.subtract(new BigDecimal("0.0001")));
35        // 1.204065
36        
37        System.out.println("Sub (2): " + a.subtract(new BigDecimal(0.0001)));
38        // 1.204064999999999999995207826397614070401687058620154857635498046875
39        
40        System.out.println("Sub (3): " + a.subtract(new BigDecimal(0.0001).setScale(6, RoundingMode.HALF_UP)));
41        // 1.204065
42        
43        System.out.println("Mult (1): " + a.multiply(new BigDecimal("0.0001")));
44        // 0.0001204165
45        
46        System.out.println("Mult (2): " + a.multiply(new BigDecimal(0.0001)));
47        // 0.000120416500000000005770567725917052914752503056661225855350494384765625
48        
49        System.out.println("Mult (3): " + a.multiply(new BigDecimal(0.0001).setScale(6, RoundingMode.HALF_UP)));
50        // 0.000120416500
51        
52        System.out.println("Mult (4): " + a.multiply(new BigDecimal(0.0001).setScale(6, RoundingMode.HALF_UP)).setScale(6, RoundingMode.HALF_UP));
53        // 0.000120
54        
55        System.out.println("Mult (5): " + a.multiply(new BigDecimal(0.0001)).setScale(6, RoundingMode.HALF_UP));
56        // 0.000120
57        
58        System.out.println("Div (1): " + a.divide(new BigDecimal("0.0001")));
59        // 12041.65
60        
61        try {
62            System.out.println("Div (2): " + a.divide(new BigDecimal(0.0001)));
63        } catch (java.lang.ArithmeticException e) { System.out.println("Div (2): " + e.getMessage()); }
64        // Non-terminating decimal expansion; no exact representable decimal result.
65        
66        System.out.println("Div (3): " + a.divide(new BigDecimal(0.0001), 6, RoundingMode.HALF_UP));
67        // 12041.650000
68        
69        System.out.println("Div (4): " + a.divide(new BigDecimal(0.0001).setScale(6, RoundingMode.HALF_UP)));
70        // 12041.65
71        
72        System.out.println("Div (5): " + a.divide(new BigDecimal(0.0001).setScale(6, RoundingMode.HALF_UP)).setScale(6, RoundingMode.HALF_UP));
73        // 12041.650000
74        
75        try {
76            System.out.println("Div (6): " + a.divide(new BigDecimal(0.0001)).setScale(6, RoundingMode.HALF_UP));
77        } catch (java.lang.ArithmeticException e) { System.out.println("Div (6): " + e.getMessage()); }
78        // Non-terminating decimal expansion; no exact representable decimal result.
79        
80        System.out.println("Abs (1): " + a.abs());
81        // 1.204165
82        
83        System.out.println("Abs (2): " + a.multiply(new BigDecimal("-1.0").setScale(6, RoundingMode.HALF_UP)).setScale(6, RoundingMode.HALF_UP).abs());
84        // 1.204165
85    }
86    
87}

As you can see creating an instance from a String is the best way to get a BigDecimal when you want to keep certain precision. Rounding and scaling play as well an important role when making calculations with BigDecimal’s.

How to read a file name argument from the command line in C++

Mon, 07 May 2018 14:20:10 +0000

Reading a file name parameter from the command line is a common task. In this post I read a file name and validate it exists. For paths and file names that include spaces, you have to pass them between quotes, otherwise they will be interpreted by the operating system as two different parameters.

 1    #include <string>
 2    #include <iostream>
 3    #include <fstream>
 4    
 5    int main(int argc, char* argv[]) {
 6        for (int i = 1; i < argc; i++) {
 7            std::string s(argv[i]);
 8            if (s.rfind("--input=", 0) == 0) {
 9                std::ifstream f(s.substr(std::string("--input=").length()));
10                if (f.good()) std::cout << "File exists" << std::endl;
11                else std::cout << "File not found" << std::endl;
12            } else {
13                std::cout << "Unknown: " << s << std::endl;
14            }
15        }
16        return 0;
17    }

How to check command line arguments in any order

Mon, 07 May 2018 14:03:54 +0000

Here is an easy solution to passing parameters to a C++ application from the command line that does not require any external libraries.

Since parameters are read inside a loop, the order in which they are passed is not important.

#include <string>
#include <iostream>

int main(int argc, char* argv[]) {
    for (int i = 1; i < argc; i++) {
        std::string s(argv[i]);
        if (s == "-a") {
            std::cout << "You passed parameter -a" << std::endl;
        } else if (s == "-b") {
            std::cout << "You passed parameter -b" << std::endl;
        } else {
            std::cout << "Unknown: " << s << std::endl;
        }
    }
    return 0;
}

Read all tables and columns from a database using Java

Wed, 02 Aug 2017 11:38:05 -0400

This Java example finds all the tables and their corresponding columns from a database. The code iterates over the entities and columns found and shows them on the console.

Minor changes are necessary to process the found values in a different way.

 1Connection conn;
 2DatabaseMetaData dmd;
 3ResultSet rs1, rs2;
 4ResultSetMetaData rsmd;
 5Statement s;
 6try {
 7    conn = getConnection();
 8    dmd = conn.getMetaData();
 9    rs1 = dmd.getTables("database_name", null, "%", null);
10    s = conn.createStatement();
11    while (rs1.next()) {
12        System.out.println("# Processing table: " + rs1.getString(3));
13        rs2 = s.executeQuery("select * from " + rs1.getString(3));
14        rsmd = rs2.getMetaData();
15        for (int i = 0; i < rsmd.getColumnCount(); i++) {
16            System.out.print(rs2.getString(i + 1) + " ");
17        }
18        System.out.println();
19        rs2.close();
20    }
21}
22catch (SQLException sqle) {
23    sqle.printStackTrace();
24}
25finally {
26    conn.close();
27}

Solution: Netbeans 8 not working on Ubuntu 15.10

Tue, 05 Apr 2016 16:31:11 +0000

Netbeans is one of my beloved day to day applications. Yesterday, when I installed Ubuntu 15.10 (Wily Werewolf) on my computer, Netbeans started to hang on the startup screen, specifically at the Loading Modules phase. It took me hours looking for solutions on the internet; and reinstalling different versions of the Java Development Framework didn’t seem to help.

Finally I found the following fix at an Ubuntu forum, which turned out to be very simple to apply.

Support Glumik!

Mon, 23 Mar 2015 14:00:58 +0000

Hello,

This time I write to ask you for your support. We’re developing a website for small business owners in the City of Queretaro, Mexico.

The website will allow the proprietors have presence on the Internet. Many of these people do not have the resources for starting a website and we want to help them. Donations start from as little as 1 dollar. The more you donate the better chance you have to get a reward, including a 1 hour call where you and I can hold a Q&A session on selected tech topics.

Installing CentOS 7 – A Graphical Tour for Linux Beginners

Thu, 22 Jan 2015 23:19:35 +0000

If you are new on the Linux platform, I am sure you feel overwhelmed with all the different versions available. Choosing one is not an easy task, and each version has its own pros and cons.

Let me tell you why I like CentOS:

It is very stable
It has well tested features
There is a big community around it
It has many large software repositories
It is Part of the RedHat / Fedora family

Installing CentOS

Installing a new operating system may seem challenging, but CentOS has always made this task a simple one.

Install CentOS 7, Oracle XE and other development tools

Thu, 22 Jan 2015 00:00:00 +0000

The CentOS distribution is a famous and stable Linux version derived from RedHat Linux. It’s been one of my favorites and one that you can easily find with hosting providers.

In this article we will install CentOS and OracleXE. It’s worth mentioning the OS team improves the installation process with each version, and you will find out in this tutorial how straightforward it currently is.

1. Installing CentOS

We’ll perform a minimal installation; this means, we will not install a graphical interface, because this server is meant to be a web / database test server.

Sunset stroll

Thu, 18 Dec 2014 06:36:02 +0000

Relaxing stroll in the desert.

Compiling and Debugging Oracle's Pro*C files in OS-X / Xcode

Thu, 18 Dec 2014 05:25:43 +0000

Part of my work as a Web/UNIX developer includes maintenance and development of tools using Oracle’s Pro*C.

In text interfaces, VIM is a pretty decent tool for creating source code and their companion make files. If you created the right make file, compiling is also a breeze. However things get kind of tricky when you have to debug. Oh my! This can be a difficult task. Many may say that there’s nothing like gdb, but come on guys, even you can’t deny the beauty of a visual debugger. But don’t get me wrong, I love UNIX and text interfaces, but I consider that there are tasks that can be performed more efficiently with the help of visual tools.

The Rationale behind the Creation of a Model-View-Controller Framework: Fantastic

Sun, 16 Nov 2014 19:24:29 +0000

Important: This is a work in progress document.

The Model-View-Controller is a software pattern frequently used for web development. As its name states, it is composed by three components:

A Model or domain representation of a problem. It receives commands, processes them and modifies its state according to the input provided.
A View whose main task is to retrieve information from the model and turn it into a useful representation for the user.
A Controller that waits for user commands and translates them into appropriate model requests.

These three components work together the following way:

Oracle Snippets

Sun, 21 Sep 2014 17:37:52 +0000

This post will be updated with snippets for Oracle. I hope you find it useful.

1. Change the default date format

Most useful snippet of the year! 😉

1ALTER SESSION SET NLS_DATE_FORMAT = 'MM/DD/YYYY HH24:MI:SS';
2select sysdate from dual;

2. Escape single quotes and ampersands on strings

Single quotes:

1select 'D''Angelo''s' from dual;

Ampersands:

1SET DEFINE OFF;

3. Adjust page width and size

1set pagesize 1000
2set linesize 100

4. Truncate a table

How to redirect stdout / stderr to a file

Mon, 15 Sep 2014 18:15:07 +0000

Redirecting all your program output to a file is very simple and can be accomplished like this:

myapp > output.log

This line will send all the output generated by myapp to a file named output.log. The contents of output.log will always be overwritten; but you can use a second > to append to the current content like this:

myapp >> output.log

As well as with output, it is very useful to redirect the stderr (standard error output) to a file rather than to the screen. You can accomplish this right from the command line like this:

RESTful URL's

Fri, 09 May 2014 00:00:00 -0400

RESTful operations on collections

Use pretty and RESTful URL’s.

GET /places

returns a list of all places

GET /places/new

returns a form to create a new place

POST /places

submits fields for creating a new place

Operate on a Record

GET /places/1

Returns place with id 1

DELETE /places/1

Destroys place with id 1

POST /places/1?_method=DELETE

Alias for DELETE, to compensate for browser limitations

GET /places/1/edit

Returns a form to edit the first record

PUT /places/1

Submits fields for updating the first record

Intro to Responsive Web Design

Sun, 16 Feb 2014 19:19:30 +0000

This weekend I was invited to have a remote presentation on Responsive Web Design with students from the Autonomous University of Queretaro (UAQ) in Mexico. Introductory concepts are presented in code, so you have the chance to apply them immediately. The video is in spanish.

Happy coding.

Create a connection to MySQL in Java

Mon, 16 Dec 2013 22:45:59 +0000

This time we are going to create a basic connection to MySQL in Java and pull some data from it.

// Compile it:
// javac Mysql.java
//
// Try it:
// java -classpath mysql-connector-java-5.1.27-bin.jar:. MySQL

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

public class MySQL {

    public Connection getConnection() throws SQLException {
        Connection conn = null;
        Properties p = new Properties();

        p.put("user", "username");
        p.put("password", "superpassword");

        String cs = "jdbc:mysql://localhost/demo";
        conn = DriverManager.getConnection(cs, p);

        return conn;
    }

    public static void main(String[] args) {
        Connection conn = null;
        ResultSet rs = null;
        Statement stmt = null;

        try {
            // Register JDBC driver
            Class.forName("com.mysql.jdbc.Driver");

            MySQL mysql = new MySQL();
            conn = mysql.getConnection();
            stmt = conn.createStatement();

            String sql = "select * from songs limit 10";
            rs = stmt.executeQuery(sql);

            while (rs.next()) {
                System.out.println(rs.getString("name"));
            }

        }
        catch (Exception e) {
            e.printStackTrace();
        }
        finally {
            try {
                if (rs != null) rs.close();
                if (stmt != null) stmt.close();
                if (conn != null) conn.close();
            }
            catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

}

Happy coding…

Installing Lucene/Solr on CentOS 6

Wed, 30 Oct 2013 00:00:59 +0000

This time we are going to install Solr, the super text search platform on CentOS. The installation process requires a couple extra libraries in order to work: Apache Commons Logging and SLF4J.

Installing Java

yum install java
java -version

You must have at least version 1.6 in order to run Solr. If you got Java 1.5, I recommend you to follow this tutorial to get version 1.6.

Installing Java 1.6 on CentOS 6

Tue, 29 Oct 2013 23:30:39 +0000

Java 1.5 is the default Java version you get when you ask yum to install it on CentOS. However, several applications need 1.6 in order to run. Just follow the next steps to install it.

Remove Java 1.5

1yum remove java-1.5-*

Install the rpmforge repository

1cd
2rpm --import http://apt.sw.be/RPM-GPG-KEY.dag.txt

Check if you have a 32 or 64 CentOS version

1uname -a

For 32 versions (i686) download and install the following repository

WordPress Snippets

Mon, 21 Oct 2013 00:12:10 +0000

As a WordPress developer I have collected / created / curated many snippets that I’ve used in my projects. I hope you find them useful.

General HTML / WordPress tags

Get your template’s directory

1<link href="<?php echo get_template_directory_uri(); ?>/style.css" rel="stylesheet" media="screen">

Check if this is the home page

1<?php if (is_home()) { ... } ?>

Remove the wp_generator tag in the Head section of your HTML

I recommend you to add this line for security reasons.

iptables snippets

Wed, 07 Aug 2013 23:04:19 +0000

iptables is the default firewall you see on any linux computer. It works by allowing (ACCEPTing) or denying (DROPing) connections to the local computer. There are basically three scenarios you can deal with:

INPUT: Connections generated from a different computer targeting yours; for example, when you run a web server on your computer and others want to connect to it.
OUTPUT: Connections generated from your computer targeting other computers; for example, when you open a web page or open a remote ssh session.
FORWARD: Connections generated from computers different than your, but that use your computer as a link to get to other computers; for example, when you share your computer’s internet connection with others, that is, when you use your computer as a router for others.

Calvin & Hobbes on real scenery

Wed, 31 Jul 2013 21:45:54 +0000

A set of beautiful images found on the Internet by an unknown artist.

How to connect to MySQL from a remote server

Tue, 30 Jul 2013 22:51:19 +0000

In few words, you have to configure MySQL to allow remote connections, create a user for connecting and setup your firewall to allow it. You don’t have to do this if you are only connecting from a local application like WordPress.

You need root permissions to perform the following commands.

Configuring MySQL

Edit the MySQL configuration file.

1nano /etc/my.cnf

Allow connections from all your network interfaces by commenting out the following line:

A divided sky

Sat, 27 Jul 2013 00:37:46 +0000

Right before the rain…

Installing MongoDB/PHP Driver on CentOS 6

Wed, 17 Jul 2013 20:28:52 +0000

Since the module is not included with the default PHP installation, you have to download it from the official repository:

1cd
2mkdir mongo-php-driver
3cd mongo-php-driver
4curl https://codeload.github.com/mongodb/mongo-php-driver/zip/master > mongo-php-driver-master.zip

Unzip it

1unzip mongo-php-driver-master.zip
2cd mongo-php-driver-master

You need _phpize _to build the module. You can install it from the remi repository:

Installing MongoDB on CentOS 6

Wed, 17 Jul 2013 17:46:56 +0000

The first step is to configure the repositories. Create the following file /etc/yum.repos.d/10gen.repo with the following contents:

For 32-bit systems:

[10gen]
name=10gen Repository
baseurl=http://downloads-distro.mongodb.org/repo/redhat/os/i686
gpgcheck=0
enabled=1

For 64-bit systems:

[10gen]
name=10gen Repository
baseurl=http://downloads-distro.mongodb.org/repo/redhat/os/x86_64
gpgcheck=0
enabled=1

Install Mongo

1yum install mongo-10gen mongo-10gen-server

Configure MongoDB

You can configure Mongo by editing the following file:

1/etc/mongod.conf

Set Mongo to autostart on system boot:

1chkconfig mongod on

Start Mongo

Unresponsive iOS7 beta 2 touch screen

Wed, 03 Jul 2013 20:59:37 +0000

Since I installed iOS7 beta 2 version, my touch screen started to go unresponsive from time to time. After a couple hours of internet research this is what I found:

iPhone unresponsiveness is mainly caused by notification messages being sent behind the lock screen. For example, when your battery reaches 20% you get a notification on your screen. There is a bug that may send those messages behind the lock screen giving you as a result an unresponsive screen – your iPhone is waiting for a response, but since you do not see the window because it is behind the lock screen, then you cannot respond… and well, you know.

Installing the PHP/MongoDB extension on Mac OSX 10.8

Thu, 27 Jun 2013 19:57:58 +0000

Installing PHP/MongoDB extension is a two steps task on OSX:

Install the autoconf tool required for compiling the extension
Install the Mongo extension

You have to install autoconf in order to avoid the following error:

1Cannot find autoconf. Please check your autoconf installation and the $PHP_AUTOCONF environment variable. Then, rerun this script.
2
3ERROR: `phpize’ failed

Enough talk, hands on work…

Step 1. Install the autoconf tool

Download the latest source version:

When I was twelve…

Tue, 30 Apr 2013 05:26:21 +0000

When I was twelve I learned something that changed my life:

110 print "Hello"
220 goto 10

1000 song names SQL test data

Wed, 10 Apr 2013 17:28:20 +0000

This time I want to share a 1000 rows SQL table that you can use for text searches. It includes a table with 1 column, 1000 rows song title names. It is plain standard SQL so you can use it with any database manager.

Download it here.

Hope you find it useful.

How to create a Finder Alias on Mac

Wed, 10 Apr 2013 07:44:10 +0000

A Finder alias is a special kind of shortcut or link to a folder. You can place this alias anywhere, being the Desktop a common place. You can even create an alias from a shared folder on a server.

To create an alias:

Open Finder and look for the folder you want to create an alias for.
Press Option + Command while you click and drag the folder to the desktop. You should see a small arrow on the ghost folder meaning you are creating an alias.
Double click on your alias to test it.

How many bytes does an "int" have in c++?

Mon, 08 Apr 2013 05:57:17 +0000

Well, that depends on several things, like your current processor and compiler. The best way to know it, is by using the sizeof operator. Copy the following code, compile it and run it:

#include <iostream>

using namespace std;

int main() {
    cout << "char: " << sizeof(char) << endl;
    cout << "int: " << sizeof(int) << endl;
    cout << "long: " << sizeof(long) << endl;
    return 0;
}

Happy coding…

Back in 1991…

Fri, 05 Apr 2013 17:40:44 +0000

From: torvalds@klaava.Helsinki.FI (Linus Benedict Torvalds)
Newsgroups: comp.os.minix
Subject: What would you like to see most in minix?
Summary: small poll for my new operating system
Message-ID: 1991Aug25.205708.9541@klaava.Helsinki.FI
Date: 25 Aug 91 20:57:08 GMT
Organization: University of Helsinki

Hello everybody out there using minix –

I’m doing a (free) operating system (just a hobby, won’t be big and professional like gnu) for 386(486) AT clones. This has been brewing since april, and is starting to get ready. I’d like any feedback on things people like/dislike in minix, as my OS resembles it somewhat (same physical layout of the file-system (due to practical reasons) among other things).

A simple Makefile

Mon, 04 Mar 2013 04:06:31 +0000

Learning how to create a Makefile is one of those tasks every C/C++ programmer has to do. Since there are many good make tutorials on the web, I’m only going to share a simplistic makefile that you can use for your projects.

CFLAGS=-c -Wall -Iinclude
LDFLAGS=-lPocoFoundation -lPocoData
SOURCES=a.cpp b.cpp main.cpp
OBJECTS=$(SOURCES:.cpp=.o)
VPATH=src

all: pre $(OBJECTS)
	g++ $(OBJECTS) -o build/main $(LDFLAGS)

.cpp.o:
	g++ $(CFLAGS) $< -o $@

pre:
	mkdir -p build

clean:
	rm -Rf build
	rm -f *.o

How to setup a FastCGI development environment in CentOS 6

Thu, 11 Oct 2012 20:24:27 +0000

Install the development environment

Install the C/C++ development tools to your server:

1yum install gcc gcc-c++ autoconf automake

Now, before installing fcgi we need to add the epel repository:

1rpm -Uvh http://dl.fedoraproject.org/pub/epel/6/i386/epel-release-6-7.noarch.rpm

Once it is installed we can proceed to get the fcgi packages:

1yum install fcgi-devel spawn-fcgi

Let’s see if we can compile a simple file. Create a file named example.c and copy and paste the following code in it:

A simple C++/Wt (Witty) skeleton for starting an application

Thu, 11 Oct 2012 18:33:06 +0000

The objective of this lesson is to show you how to make a simple web page navigation using Wt. Before starting you have to remember that Wt can be used to create 1 URL applications. That means you can have a full application that runs using just one URL. However it is also useful to give your users different URL’s to take advantage of some browser features like bookmarks or the back and forward buttons.

How to use a WComboBox with C++/Wt (Witty)

Wed, 10 Oct 2012 21:00:31 +0000

In this entry I’m going to create a simple form that shows how to add items to WComboBox in two different ways. The first one is useful for static combo items while the second one might be used to populate a combo from a database.

The code is based on our previous Hello World application. There are few lines that changed.

Creating a simple form using C++/Wt (Witty)

Wed, 10 Oct 2012 20:12:55 +0000

In this entry I’m going to create a simple form. This form will show you how to use controls and events in a very simple way.

A couple things you have to notice before we start:

I’m going to inherit from WContainerWidget. As you now know, I could have inherited from WApplication too.
Most controls like, WLabel, WLineEdit and WPushButton include a “parent” parameter in their constructors. But you can also create them and add them later to any WContainerWidget. I’m doing this to our text control. To add it to a container you have to call the WContainerWidget::addWidget method.
The code is based on our previous Hello World application. There are few lines that changed.

So, here it is:

Two ways to create a Hello World application with Wt (Witty)

Tue, 09 Oct 2012 17:49:19 +0000

Let’s start by talking a little bit about some elements and methods you will find in the code.

Inheriting from WApplication or WContainerWidget are the most common ways to start an application using Wt. A WApplication instance will be in charge of creating your html, head and body tags. A WContainerWidget is usually a div tag (it can also be turned into a ul or ol by using its setList method). If you want to add items to your body tag, you have to ask your application for the root element by using the root() method – the root element does not really correspond to the body tag but it is close to it… it is a div.

Steve Jobs

Fri, 05 Oct 2012 14:50:35 +0000

Steve, we are still hungry… we are still foolish…

Where does Windows Live Writer store themes

Wed, 03 Oct 2012 05:28:49 +0000

Windows Live Writer makes a local copy of your website images and style sheets everytime you click on the Update Theme button located in the Blog Account ribbon.

You can find your local CSS file(s) in the following folder on Windows 7:

C:UsersYour NameAppDataRoamingWindows Live Writerblogtemplates

If you only have one blog, you are lucky. Get into the only folder you find there. If you have many blogs it will be a trial and error process to find out the right folder where your CSS files are located. You can ease this task by updating your theme from Windows Live Writer and then sorting these folders by date. Once you get into the right folder, look for your CSS. There might be more than one copy of it in these folders, so be sure to update them all.

How to install Wt (Witty) on Windows

Tue, 02 Oct 2012 20:11:32 +0000

Installing Wt can be a challenging task if you don’t have the right tools. I spent many days trying to make it work with MinGW and Visual Studio 2005. No luck. Here are some of my results:

MinGW

I was never able to make a full compile. It was interrupted by this or that reason. I could never get any of the examples to work.

Visual C++ Express 2005

Some of the examples worked, however only in “Release” mode. They never worked in debug mode, even though they compiled and linked successfuly. The INSTALL project didn’t work ethier.

Child memories…

Mon, 01 Oct 2012 23:14:26 +0000

We were so nerds…

C:>debug
a
mov ah,9
mov dx,108
int 21
ret
db 'hello world$'

r cx
14
n hello.com
w
q

How to install the C++ Boost Libraries on Windows

Thu, 27 Sep 2012 23:34:27 +0000

Boost is a set of high-quality libraries that speed up C++ development. They are included in most linux distributions and some of them are already part of the C++ Standard Library. In the Windows environment, you have to install them in order to take advantage of them.

If you are using Microsoft Visual Studio, you can avoid the following steps by downloading a binary version from http://www.boostpro.com/download/ and skip to the Testing section in this document.

One-liner to minimize your CSS files

Thu, 27 Sep 2012 17:37:05 +0000

The following one-liner will help you remove comments, spaces, and more from your CSS files. Suggestions are always welcomed.

Important: Before running this command, create a copy of your original file. Try the resulting CSS in a test environment before releasing it.

cat style.css | sed -e '
s/^[ t]*//g;         # leading spaces
s/[ t]*$//g;         # trailing spaces
s/([:{;,]) /1/g;   # spaces after a colon, brace, semicolon, or comma
s/ {/{/g;             # spaces before a brace
/^$/d                 # blank lines
' | sed -e :a -e '$!N; s/n(.)/1/; ta # newlines
' | sed -e 's//*[^*]**///g;'         # comments

Installing gcc/g++ using MinGW and NetBeans in Windows

Thu, 27 Sep 2012 16:44:07 +0000

C and C++ languages are everywhere. All operating systems use them. People usually choose them because of their limitless power, velocity of execution, great portability and much more. In this tutorial I will show you how to install a C/C++ development environment under Windows. By the way, MinGW includes other compilers for languages like c, c++, objective c fortran and ada.

Install MinGW

Go to the MinGW website and look for the download link. You can get it directly from SourceForge.

Start the installation.
Under Repository Catalogues, select Download latest repository catalogues. You can also keep the Use pre-packaged repository catalogues if your package includes a recent snapshot.

Select your installation path. Try to select one that is easily accesible from the command line.
Note: I have changed my default installation directory to C:optMinGW. This is completely optional.

Select C, C++ and other languages you want to install, plus the MSYS Basic System. MSYS includes several handy shell tools like bash, make and grep that will allow you to build applications that depend on UNIX tools to be present.

Continue through the wizard screens and press Install.
If you chose the option to download the latest repositories, it will take a little bit more.

In order to access your compilers from any directory in your system you now have to add the following directories to your PATH environment variable:

Switch from Debug to Release build options in Delphi

Wed, 26 Sep 2012 19:26:52 +0000

Unlike Microsoft’s Visual Studio, the option to switch from Debug to Release in Delphi is kind of hidden. However, it is very easy to use.

Go to the Project menu and select Configuration Manager
Now select your project,
Choose a new configuration and
Press the “play” button.

The following picture shows you how the Configuration Manager looks:

By default, the difference between the Debug and the Release options include:

Local Symbols creation (Debug: On, Release: Off)
Symbol Reference Info (Debug: Include, Release: None)
Debug Information (Debug: On, Release: Off)

If you want to make further configurations, go to the Project menu and select Options. The options below Delphi Compiler and Resource Compiler will let you adjust every little nut.

How to create high definition images for the iPad Retina display

Tue, 18 Sep 2012 22:30:23 +0000

So you got a new iPad and realized your images do not look as good as they do on your computer, right? Don’t worry, there is a very simple way to achieve good looking images on this device:

If you want to create a 500 x 500 px on a Retina display, create an image at 1000 x 1000 and then use CSS to control the image size down to 500 x 500:

Working with dynamic arrays in Delphi

Tue, 18 Sep 2012 00:02:17 +0000

One advantage of Delphi’s dynamic arrays is that they are automatically freed once they go out of scope. That simplifies memory management and gives you more flexibility on your applications.

You can declare a dynamic array like this:

Customers: array of string;

Before adding an element, you have to call the SetLength function to specify the number of elements you are going to use (3 in this case):

SetLength(Customers, 3);

Tips to help you deal with Delphi Threads

Mon, 17 Sep 2012 20:10:46 +0000

Multithreading is one of those operating systems feaures that make your programs work in a more efficient way and give your users a better interactive interface. However they are not used by all developers.

In this article I will focus on some important points you must have in mind when using threads on Delphi.

How to create them

There are two simple steps to accomplish it:

Create a new class that inherits from TThread and
Override the Execute method.

TMyThread = class(TThread)
public
  procedure Execute; override;
end;

procedure TMyThread.Execute;
begin
   DoSomeWork();
  //When the procedure ends, the thread ends.
end;

Minor changes

Tue, 04 Sep 2012 21:04:44 +0000

I have applied some minor changes to this website: caching – to improve performance – and micro-blogging entries. Later I will add some style to the micro-entries.

How to manage local or remote services from command line

Tue, 04 Sep 2012 15:19:06 +0000

Starting or stopping services on Windows is a task commonly performed by using the Services snap-in on the MMC console. From time to time you want to perform such tasks from the command line. A possible reason for this is when you are creating scripts (batch files).

To achieve this, you have two options: net for managing local services and sc.exe for remote ones.

The net command is included in your default Windows installation. The sc.exe is installed as part of the Windows Resource Kit Tools. You can download it directly from here.

Exchange: The database files in this storage are inconsistent

Wed, 29 Aug 2012 18:10:30 +0000

This morning I got a new surprise from my Exchange server. Outlook clients could not connect to the servers, however the server seemed to be working pretty normal. After some research I found out the Exchange databases were corrupted. But, how did this happen? Well, they can get corrupted when Windows is not shutdown in a proper way, or a service or process misbehavior leaves them in an inconsistent state or when there are physical errors on your hard disk. In my case it was caused by an improper behavior of the VSS service generated by BackupExec.

Creating Shortcodes in WordPress

Mon, 27 Aug 2012 01:58:45 +0000

Shortcodes enable developers to create special kinds of content, following the idea of macros. One very famous short code is “gallery” needed to insert a gallery of images into a post.

The good thing about shortcode’s is that final users are free to decide where to insert them.

WordPress’s Shortcode API handles all the tricky parsing, making developers life much easier. The following is a snippet for a Shortcode – in order to make it work you have to add it to your functions.php file in your theme’s directory.

Add a Thumbnail to Admin Post Columns in WordPress

Mon, 27 Aug 2012 00:40:32 +0000

Here is a snippet to add 64×64 images to the Admin Post Columns in WordPress. Having thumbnails may result extremely helpful, specially if you have hundreds of posts.

You have to copy and paste the following code into the functions.php file of your theme.

function posts_columns($defaults){
    $defaults['the_post_thumbs'] = __('Thumbs');
    return $defaults;
}

function posts_custom_columns($column_name, $id){
        if($column_name === 'the_post_thumbs'){
        echo the_post_thumbnail( array(64, 64) );
    }
}

add_filter('manage_posts_columns', 'posts_columns');
add_action('manage_posts_custom_column', 'posts_custom_columns', 10, 2);

How I made my HP LaserJet P1102w work with my iPad

Wed, 15 Aug 2012 05:00:33 +0000

I got an HP LaserJet P1102w about a year ago, so long before I thought I was going to get an Apple’s iOS device. I purchased it just because I thought it would be useful to have a printer that could work wirelessly.

At that time I made it work using wireless, but for some reason it stopped working. I didn’t care because it was very simple to connect it via USB to my computer and get my stuff done.

Download YouTube videos using Java

Thu, 02 Aug 2012 18:40:00 +0000

From time to time we all have needed to show a YouTube video where no Internet connection is available.

This program will allow you to download a video from YouTube for later playback. It is important to say that YouTube constantly changes its video URL, so someday it may need some rework. The following code was tested on Aug 12, 2012 and it works.

Have a good day.

/**
 * YouTubeDownloader
 *
 * Modified by Andres Jaimes https://andres.jaimes.net
 * Updated on Aug 02 2012
 * Based on http://stackoverflow.com/users/568438/pinkteddybear888
 *
 * Dependencies: HttpComponents (http://hc.apache.org/index.html)
 *
 * -classpath .httpcomponents-client-4.2.1libhttpcore-4.2.1.jar;
 *            .httpcomponents-client-4.2.1libhttpclient-4.2.1.jar;
 *            .httpcomponents-client-4.2.1libcommons-logging-1.1.1.jar;
 */

import java.io.BufferedReader;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.StringWriter;
import java.io.UnsupportedEncodingException;
import java.io.Writer;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.URLDecoder;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import java.util.logging.Formatter;
import java.util.logging.Handler;
import java.util.logging.Level;
import java.util.logging.LogRecord;
import java.util.logging.Logger;
import java.util.regex.Pattern;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.CookieStore;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.protocol.ClientContext;
import org.apache.http.client.utils.URIUtils;
import org.apache.http.client.utils.URLEncodedUtils;
import org.apache.http.impl.client.BasicCookieStore;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.protocol.BasicHttpContext;
import org.apache.http.protocol.HttpContext;

public class YouTubeDownloader {

    public static String newline = System.getProperty("line.separator");
    private static final Logger log = Logger.getLogger(JavaYoutubeDownloader.class.getCanonicalName());
    private static final Level defaultLogLevelSelf = Level.FINER;
    private static final Level defaultLogLevel = Level.WARNING;
    private static final Logger rootlog = Logger.getLogger("");
    private static final String scheme = "http";
    private static final String host = "www.youtube.com";
    private static final Pattern commaPattern = Pattern.compile(",");
    private static final Pattern pipePattern = Pattern.compile("|");
    private static final char[] ILLEGAL_FILENAME_CHARACTERS = { '/', 'n', 'r', 't', '', 'f', '`', '?', '*', '', '<', '>', '|', '"', ':' };

    private static void usage(String error) {
        if (error != null) {
            System.err.println("Error: " + error);
        }
        System.err.println("usage: YouTubeDownloader VIDEO_ID DESTINATION_DIRECTORY");
        System.exit(-1);
    }

    public static void main(String[] args) {
        if (args == null || args.length == 0) {
            usage("Missing video id. Extract from http://www.youtube.com/watch?v=VIDEO_ID");
        }
        try {
            setupLogging();

            log.fine("Starting");
            String videoId = null;
            String outdir = ".";
            // TODO Ghetto command line parsing
            if (args.length == 1) {
                videoId = args[0];
            } else if (args.length == 2) {
                videoId = args[0];
                outdir = args[1];
            }

            int format = 18; // http://en.wikipedia.org/wiki/YouTube#Quality_and_codecs
            String encoding = "UTF-8";
            String userAgent = "Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.13) Gecko/20101203 Firefox/3.6.13";
            File outputDir = new File(outdir);
            String extension = getExtension(format);

            play(videoId, format, encoding, userAgent, outputDir, extension);

        } catch (Throwable t) {
            t.printStackTrace();
        }
        log.fine("Finished");
    }

    private static String getExtension(int format) {
        // TODO: See reference http://en.wikipedia.org/wiki/YouTube#Quality_and_codecs
        return "mp4";
    }

    private static void play(String videoId, int format, String encoding, String userAgent, File outputdir, String extension) throws Throwable {
        log.fine("Retrieving " + videoId);
        List<NameValuePair> qparams = new ArrayList<NameValuePair>();
        qparams.add(new BasicNameValuePair("video_id", videoId));
        qparams.add(new BasicNameValuePair("fmt", "" + format));
        URI uri = getUri("get_video_info", qparams);

        CookieStore cookieStore = new BasicCookieStore();
        HttpContext localContext = new BasicHttpContext();
        localContext.setAttribute(ClientContext.COOKIE_STORE, cookieStore);

        HttpClient httpclient = new DefaultHttpClient();
        HttpGet httpget = new HttpGet(uri);
        httpget.setHeader("User-Agent", userAgent);

        log.finer("Executing " + uri);
        HttpResponse response = httpclient.execute(httpget, localContext);
        HttpEntity entity = response.getEntity();
        if (entity != null && response.getStatusLine().getStatusCode() == 200) {
            InputStream instream = entity.getContent();
            String videoInfo = getStringFromInputStream(encoding, instream);
            if (videoInfo != null && videoInfo.length() > 0) {
                List<NameValuePair> infoMap = new ArrayList<NameValuePair>();
                URLEncodedUtils.parse(infoMap, new Scanner(videoInfo), encoding);
                String token = null;
                String downloadUrl = null;
                String filename = videoId;

                for (NameValuePair pair : infoMap) {
                    String key = pair.getName();
                    String val = pair.getValue();
                    log.finest(key + "=" + val);
                    if (key.equals("token")) {
                        token = val;
                    }
                    else if (key.equals("title")) {
                        filename = val;
                    }
                    else if (key.equals("url_encoded_fmt_stream_map")) {
                        downloadUrl = URLDecoder.decode(
                            val.substring(val.indexOf("http"),
                            val.indexOf("&")), "UTF-8");
                    }
                }

                filename = cleanFilename(filename);
                if (filename.length() == 0) {
                    filename = videoId;
                }
                else {
                    filename += "_" + videoId;
                }
                filename += "." + extension;
                File outputfile = new File(outputdir, filename);

                log.finer("Saving to " + outputfile);
                log.finer("From " + downloadUrl);

                if (downloadUrl != null) {
                    downloadWithHttpClient(userAgent, downloadUrl, outputfile);
                }
            }
        }
    }

    private static void downloadWithHttpClient(String userAgent, String downloadUrl, File outputfile) throws Throwable {
        HttpGet httpget2 = new HttpGet(downloadUrl);
        httpget2.setHeader("User-Agent", userAgent);

        log.finer("Executing " + httpget2.getURI());
        HttpClient httpclient2 = new DefaultHttpClient();
        HttpResponse response2 = httpclient2.execute(httpget2);
        HttpEntity entity2 = response2.getEntity();
        if (entity2 != null && response2.getStatusLine().getStatusCode() == 200) {
            long length = entity2.getContentLength();
            InputStream instream2 = entity2.getContent();
            log.finer("Writing " + length + " bytes to " + outputfile);
            if (outputfile.exists()) {
                outputfile.delete();
            }
            FileOutputStream outstream = new FileOutputStream(outputfile);
            try {
                byte[] buffer = new byte[2048];
                int count = -1;
                while ((count = instream2.read(buffer)) != -1) {
                    outstream.write(buffer, 0, count);
                }
                outstream.flush();
            } finally {
                outstream.close();
            }
        }
    }

    private static String cleanFilename(String filename) {
        for (char c : ILLEGAL_FILENAME_CHARACTERS) {
            filename = filename.replace(c, '_');
        }
        return filename;
    }

    private static URI getUri(String path, List<NameValuePair> qparams) throws URISyntaxException {
        URI uri = URIUtils.createURI(scheme, host, -1, "/" + path, URLEncodedUtils.format(qparams, "UTF-8"), null);
        return uri;
    }

    private static void setupLogging() {
        changeFormatter(new Formatter() {
            @Override
            public String format(LogRecord arg0) {
                return arg0.getMessage() + newline;
            }
            });
        explicitlySetAllLogging(Level.FINER);
    }

    private static void changeFormatter(Formatter formatter) {
        Handler[] handlers = rootlog.getHandlers();
        for (Handler handler : handlers) {
            handler.setFormatter(formatter);
        }
    }

    private static void explicitlySetAllLogging(Level level) {
        rootlog.setLevel(Level.ALL);
        for (Handler handler : rootlog.getHandlers()) {
            handler.setLevel(defaultLogLevelSelf);
        }
        log.setLevel(level);
        rootlog.setLevel(defaultLogLevel);
    }

    private static String getStringFromInputStream(String encoding, InputStream instream) throws UnsupportedEncodingException, IOException {
        Writer writer = new StringWriter();

        char[] buffer = new char[1024];
        try {
            Reader reader = new BufferedReader(new InputStreamReader(instream, encoding));
            int n;
            while ((n = reader.read(buffer)) != -1) {
                writer.write(buffer, 0, n);
            }
        } finally {
            instream.close();
        }
        String result = writer.toString();
        return result;
    }
}

Free Image Resizer for Windows

Tue, 31 Jul 2012 21:40:18 +0000

This time I want to share with you a Windows application for image resizing. It’s a fact, size matters. That is why Image Resizer can be very useful for sharing pictures through email, uploading images to websites or posting them to social networks. If your images are smaller, then it will take you less time to share them.

This application can load a list of jpeg, gif, png or bmp files, resize them and then put them on a selected folder. All this without modifying your original files. This application uses a smooth image resizing algorithm to get better and softer images. This application does not need an installer; it just runs from whatever folder you put it in. If someday you want to “uninstall” this application, just delete this file and that’s it.

How to avoid spam on Android's message bar

Tue, 24 Jul 2012 18:05:04 +0000

Recently, I started to get some really anoying spam messages from an unknown application on my phone’s message bar. Different icons were showing like stars, plus signs, check marks and so on. When you select any of this messages your browser opens and takes you to the leadbolt website. These ads started to become something annoying and I started to wonder if they were messing with my personal information.

How to proceed

In order to identify the offender app, you have to install AirPush Detector (free app) written by Dan Bjorge from the Play Store.

10 WordPress plugins you should have

Tue, 12 Jun 2012 21:49:00 +0000

This time I would like to make a list of recommended WordPress plugins. They are alphabetically sorted and have many different purposes. The descriptions shown were taken right from the WordPress description.

Here we go:

1. Comment Rating

By Bob King
Description: Allows visitors to rate comments in a Like vs. Dislike fashion with clickable images. Poorly-rated & highly-rated comments can be displayed differently. This plugin is simple and light-weight.

5 tips to get good pictures in low light conditions

Sun, 03 Jun 2012 22:51:23 +0000

I recently got an assignment to cover a music school’s annual concert. But it was not as easy I thought it was going to be.

First of all, the concert took place in a very dark auditorium. There was just one working spot light pointing to the right side of the stage. The sun was bright outside and there some windows right behind the stage. For some reason, that I did not understand, they didn’t allow me to use a flash. With musicians moving over and over from light to darkness and back, that was a good challenge.

Useful vim commands

Fri, 25 May 2012 16:44:13 +0000

Even though we have many sophisticated GUI text editors, there is one that has passed all time tests: vi.

vi is a text editor created originally for Unix in 1976. Are you kidding? 1976? Why should I even bother to know it exists? Because that is the only text editor you will find for sure in any Unix like command line environment, that includes any Unix flavor, Linux and Macs. Believe me, there are many times when you have no other way to edit files (like webpages, php’s, css’s) but from the command line. Also your customer will be very impressed when he looks at you doing all this stuff. Really.

A basic .vimrc configuration file for vim users

Fri, 25 May 2012 15:56:57 +0000

.vimrc is the configuration file for vim. Upon execution vim will read the contents of this file setting up a customized environment. You have to save this file in your home directory. It is important to notice that the commands should not include the initial colon (:).

Here are some useful commands:

syntax on          " syntax highlighing
set number         " show line numbers
set ruler          " show the cursor position all the time
set ignorecase     " ignore case when searching
set hlsearch       " highlight searches
set tabstop=4      " number of spaces of tab character
set shiftwidth=4   " number of spaces to (auto)indent
set autoindent     " always set auto indenting on
set smartindent    " smart indent
set cindent        " cindent

If you are using vi instead of vim, then save your configuration to ~/.exrc

About Me

Wed, 14 Mar 2012 23:04:50 +0000

I am a Cloud, REST API, and microservices back-end/full-stack developer, fluent in Scala, Java, C#, JavaScript, SQL, NoSQL, and ElasticSearch, who loves FreeBSD, Linux, Docker and AWS.

I started programming web pages when bright-colored-blinking gifs dominated the internet. That new place where Geocities ruled. Those were the times when creating a simple contact form required a CGI program using C or C++, Boutell’s CGIC library, and the Netscape Composer.

I am a big fan of the Mario Bros saga and an avid player of The Legend of Zelda: Breath of the Wild. I’m a piano and guitar player and enjoy road cycling and playing tennis.

Multi-Device Layout Patterns

Wed, 14 Mar 2012 22:51:43 +0000

Through fluid grids and media query adjustments, responsive design enables Web page layouts to adapt to a variety of screen sizes. As more designers embrace this technique, we’re not only seeing a lot of innovation but the emergence of clear patterns as well. I cataloged what seem to be the most popular of these patterns for adaptable multi-device layouts.

To get a sense of emerging responsive design layout patterns, I combed through all the examples curated on the Media Queries gallery site several times. I looked for what high-level patterns showed up most frequently and tried to avoid defining separate patterns where there were only small differences.

Old school: Use xcopy to back up your stuff

Thu, 08 Mar 2012 22:24:18 +0000

Need an easy way to back up your files, but don’t feel like monkeying with expensive or complicated software? Using the xcopy command and a simple text file, you can accomplish this rather easily. Here’s what I do.

First, make sure that file extensions are not hidden by going to My Computer > Tools > Folder Options > View. Uncheck Hide Extensions for Known File Types and click OK (if it’s already unchecked, don’t worry about it).

Ten Laws to Design By

Fri, 02 Mar 2012 07:54:40 +0000

As designers we have to be aware of the function of our work and design as much as we care about the aesthetics and visuals. There are a lot of terms for the design of how the site functions and works, from “usability design” to “user experience,” what remains constant is that if we want to become better designers we have to pair these two concepts together.

Using clear and effective design laws as guides we can use proven formulas for better design. These laws both assist in the usability / experience of our design as well as the aesthetic values. Furthermore being able to refer and cite these laws when presenting or discussing design you can further establish yourself as a expert with justified reasons for your design choices.

Desprotegido…

Mon, 27 Feb 2012 19:28:07 +0000

No fue hasta que un señor de cincuenta y tantos años, cuyo padre recientemente falleció, que entendí la importancia de sentirnos cerca de nuestros padres, pues me dijo “ahora sí me siento desprotegido”…

Coding An HTML 5 Layout From Scratch

Sat, 25 Feb 2012 22:03:15 +0000

HTML5 and CSS3 have just arrived (kinda), and with them a whole new battle for the ‘best markup’ trophy has begun. Truth to be told, all these technologies are mere tools waiting for a skilled developer to work on the right project. As developers we shouldn’t get into pointless discussions of which markup is the best. They all lead to nowhere. Rather, we must get a brand new ideology and modify our coding habits to keep the web accessible.

Redistribute your webpage contents to fit your browser width

Wed, 22 Feb 2012 04:37:22 +0000

Are you tired of dealing with different screen sizes for your web pages? Well, this information is for you.

I will show you some CSS tricks to help you reorganize a webpage depending on your browser window width.

We will start with a simple HTML 5 skeleton that includes a contents and a navigation section:

 1<!DOCTYPE html>
 2<html lang="en">
 3<head>
 4  <style>
 5    /* we will add our style here on the next step */
 6  </style>
 7</head>
 8<body>
 9  <div role="main">
10    <h1>This is the contents</h1>
11    <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit.
12       Nunc venenatis ante sed augue porttitor at volutpat felis
13       consequat. Pellentesque eget neque vel erat cursus
14       fermentum. Cras convallis eros malesuada lectus condimentum
15       a semper eros sollicitudin. Phasellus bibendum, elit in
16       facilisis volutpat, felis nisl venenatis mauris, non
17       vestibulum diam urna id eros. Proin augue mauris, aliquam
18       condimentum suscipit vel, semper sit amet orci. Pellentesque
19       eleifend, sem in feugiat ultrices, lacus diam luctus turpis,
20       quis malesuada dui risus et magna. Donec egestas, ligula in
21       faucibus accumsan, lacus nibh condimentum urna, vel pulvinar
22       nulla mi quis turpis. </p>
23  </div>
24  <nav role="navigation">
25    <h2>This is the navigation.</h2>
26    <ol>
27      <li><a href="#">Option 1</a></li>
28      <li><a href="#">Option 2</a></li>
29      <li><a href="#">Option 3</a></li>
30    </ol>
31  </nav>
32</body>
33</html>

Pretty simple uh? Now, we will add some CSS between the style tags in the head section. This CSS will do the magic depending on our window width.

An easy way to do a CSS Horizontal Menu

Wed, 22 Feb 2012 03:27:23 +0000

Here it is. Start with a conventional item list like the following:

1<ul class="hmenu">
2    <li><a href="">Option 1</a></li>
3    <li><a href="">Option 2</a></li>
4    <li><a href="">Option 3</a></li>
5    <li><a href="">Option 4</a></li>
6    <li><a href="">Option 5</a></li>
7</ul>

Don’t forget to add the class parameter to the ul tag – that will help us do the magic. The previous list is rendered in a regular browser like the following:

CSS – Attribute selectors

Tue, 21 Feb 2012 23:06:55 +0000

Attribute selectors allow you to select CSS elements based on their attributes or values.

For example, if you want to select an image named “great.gif” you can do it by using the following rule:

1img[src="great.gif"] { border: 3px solid #000; }

There are four types of selectors.

By attribute. The following example will select all the images that contain the given attribute:

1img[title] { border: 3px solid #000; }
2img[width] { border: 3px solid #000; }
3img[alt] { border: 3px solid #000; }

By value. This will look for all elements that have a “src” attribute with the given value:

Create a DNS zone file

Tue, 21 Feb 2012 21:45:20 +0000

by FreeBSD.org

An example master zone file for example.org (existing within /etc/namedb/master/example.org) is as follows:

$TTL 3600        ; 1 hour default TTL
example.org.    IN      SOA      ns1.example.org. admin.example.org. (
                                2006051501      ; Serial
                                10800           ; Refresh
                                3600            ; Retry
                                604800          ; Expire
                                300             ; Negative Response TTL
                        )

; DNS Servers
                IN      NS      ns1.example.org.
                IN      NS      ns2.example.org.

; MX Records
                IN      MX 10   mx.example.org.
                IN      MX 20   mail.example.org.

                IN      A       192.168.1.1

; Machine Names
localhost       IN      A       127.0.0.1
ns1             IN      A       192.168.1.2
ns2             IN      A       192.168.1.3
mx              IN      A       192.168.1.4
mail            IN      A       192.168.1.5

; Aliases
www             IN      CNAME   example.org.

Note that every hostname ending in a “.” is an exact hostname, whereas everything without a trailing “.” is relative to the origin. For example, ns1 is translated into ns1.example.org.

CentOS useful commands

Tue, 21 Feb 2012 00:15:36 +0000

To get your CentOS version type:

1cat /etc/redhat-release

To update all your CentOS packages at once:

1yum update

To install nslookup, dig and other network utilities:

1yum install bind-utils -y

Show User Library Directory in Mac OS X Lion

Sat, 18 Feb 2012 21:31:14 +0000

Show User ~/Library in OS X Lion

Launch Terminal from Spotlight or Launchpad > Utilities, and enter the following command to show the directory:
``

chflags nohidden ~/Library/

The users Library folder will immediately become visible. Reverting this back to the standard Lion setting is simple too:

Hide User ~/Library in OS X Lion (default setting)

This returns to the default setting of hiding the user Library directory:
``

How to create a simple gradient in C#

Sat, 18 Feb 2012 01:02:51 +0000

Creating a simple gradient using two colors is very simple:

1Rectangle rect = new Rectangle(0, 0, 100, 100);
2LinearGradientBrush lgb = new LinearGradientBrush(rect, Color.White, Color.Blue, 90);
3e.Graphics.FillRectangle(lgb, rect);

This code will generate a gradient in the given rectangle that goes from white to blue in a vertical way (see last parameter in constructor). In this case, e, is any class that encapsulates the System.Drawing.Graphics class. Once the gradient is ready, well, you have to actually draw it by calling the FillRectangle function.

Printing in C# – The easy way

Sat, 18 Feb 2012 00:25:11 +0000

Believe me, it is easy. As with any class, before we can use any of the Classes, Events and Objects available to us in the .Net Framework we need to import the Namespaces we need. For this we need 3 namespaces. VB.Net users only required 2 because VB.Net assumes the System Namespace, whereas C# isn’t so kind:

System
System.Drawing
System.Drawing.Printing

These 3 Namespaces contain everything we need for this class, so you will need to add the following lines to the top of your class file:

How to know if a hex color is light or dark

Fri, 17 Feb 2012 23:12:23 +0000

There is a simple way to know this. The following code takes white (#ffffff) divided it by two as our reference color. If the comparing color is lower than the reference color, then the given color is dark, otherwise it’s light color.

1    function isLightOrDark($hexcolor) {
2     return (hexdec($hexcolor) > 0xffffff/2) ? 'light color' : 'dark color';
3    }

How to choose a printer using C#

Fri, 17 Feb 2012 23:01:45 +0000

You can assign a printer and other settings by using the basic PrintDocument and PrintDialog controls properties. Look at the next example:

1if (printDialog.ShowDialog() == DialogResult.OK) {
2    printDocument.PrinterSettings.PrinterName = printDialog.PrinterSettings.PrinterName;
3    printDocument.PrinterSettings.Copies = printDialog.PrinterSettings.Copies;
4}

How to Move a WordPress Blog to a New Domain or Location

Tue, 14 Feb 2012 01:24:27 +0000

Before trying the queries in this page, I recommend you to read this full article to learn more about the process.

To update WordPress options with the new blog location, use the following SQL command:

1UPDATE wp_options SET option_value = replace(option_value, 'http://www.old-domain.com', 'http://www.new-domain.com') WHERE option_name = 'home' OR option_name = 'siteurl';

After that you will need to fix URLs of the WordPress posts and pages, which translated from post slug, and stored in database wp_posts table as guid field. The URL values in this field are stored as absolute URLs instead of relative URLs, so it needs to be changed with the following SQL query:

Kiwi!

Sat, 14 Jan 2012 18:25:42 +0000

Worth watching

How to install Papyrus on Eclipse Indigo

Tue, 10 Jan 2012 23:10:46 +0000

Papyrus is a UML designer plugin for the eclipse development environment. Installing it on the Indigo version is very easy:

Go to Help > Install New Software…
Under Work with, select All Available Sites and look for Modeling on the tree view.
Under Modeling, look for MDT Papyrus – SDK and press the Next button
Press Next again
Accept the Licence and press Finish
You will be asked to restart Eclipse, so go ahead…
Next time you create a project, you will see the Papyrus project listed.

Happy modeling!

Reocities, a web time traveller…

Tue, 25 Oct 2011 19:26:03 +0000

If you are one of those who started surfing and creating the web in the 90’s, Reocities will take you back in time to the beginning of an era. Blue text on green or yellow wallpapers and animated gif’s overloaded the pages during the last decade of last century.

After Geocities closed in 2009, Reocities started saving a lot of websites stored on mentioned website trying to keep the history alive. A real virtual museum.

Hombres G vs Jason Paradise

Tue, 25 Oct 2011 18:33:09 +0000

A quick note for Hombres G fans… on this video they discuss about Jason’s like on iPad’s. Enjoy it.

Cómo agregar la fecha al nombre de un fichero en linux o mac

Fri, 05 Aug 2011 00:34:48 +0000

Agregar la fecha a un nombre de un fichero desde un script es muy útil, pues te permitirá generar nombres únicos para, por ejemplo, crear una lista de respaldos.

Aquí os dejo un script muy sencillo que ejemplifica cómo hacerlo:

#!/bin/sh

dt=`date +%y%m%d`
touch ./archivo-$dt

Este es un programa muy sencillo el cual asigna a la variable “dt” el resultado de ejecutar el comando date +%y%m%d, el cual devuelve la fecha en formato año, mes y día. Es importante que veais el uso del acento grave (`) para que funcione.

Google+

Thu, 21 Jul 2011 17:40:00 +0000

El día de hoy obtuve una de las codiciadas cuentas en Google+. A primera vista pareciera que estamos tratando con una copia de FaceBook, pues tiene cosas como los mensajes de estado y las fotografías… pero esconde muchas otras más.

No more spam…

Tue, 07 Jun 2011 17:02:53 +0000

Ok spammers, I’m tired.

During the last weeks I was getting about 100 spam messages per hour. That was very difficult to control. So I decided to take that as an opportunity to upgrade my server. Now my website runs on the latest WordPress engine and I have also installed some new antispam plugins.

All the website contents will be updated and uploaded during this month.

I appreciate your patience while I finish applying this upgrade.

Comments have been temporarly disabled…

Fri, 13 May 2011 19:45:32 +0000

Sorry everyone, but I was getting the incredible quantity of 60 spam comments per hour… I will reopen them as soon as I get a good tool to fight spam…

Thanks!

Java, brigther than ever

Thu, 16 Dec 2010 02:38:34 +0000

Java, the programming language for many of us, is shinning more than ever! Just see how Android (Google’s operating system) uses it for its applications:

http://en.wikipedia.org/wiki/Android_%28operating_system%29

Windows Live Writer? nah… Adobe Contribute

Sat, 20 Nov 2010 16:38:38 +0000

Obsesed with looking for a good blogging tool on the web and reading a big list of complaints for the lack of a good tool for mac users, I didn’t realize I had had one for a long time on my computer: Adobe Contribute. Most people talk about Microsoft’s Windows Live Writer and how to run it on a Mac, but forget about this good option that runs natively on it.

How to access a Web service from a C# Desktop Application

Tue, 09 Feb 2010 19:56:17 +0000

This project will teach you how to create a C# Desktop Application that uses a Web Service as its backend. You will need Visual Web Developer Express and Visual C# Express.

Step 1: Creating the Web Service

Open Visual Web Developer and go to File > New Project. Under Project Types select Visual C# > Web. Under Templates select ASP.NET Web Service Application. Press the Ok button.

ASP.NET Tips & Tricks

Tue, 18 Aug 2009 14:50:51 +0000

How to get the user name in a web app

Four steps to achieve it:

Use the following code to get the user name in your application:

string user = User.Identity.Name.ToString();

Modify your web.config file to include the identity and the authentication tags:

<system.web>        
        <identity impersonate="true" />
        <authentication mode="Windows"/>
</system.web>

In IIS right click your application and select Properties. Go to the Directory Security tab. Click Edit under Authentication and Access Control. Uncheck Enable anonymous access and check Integrated Windows authentication. Click Ok to save your changes.
Open Windows Explorer, go to your application folder and modify permissions to allow your users (and not the IIS anonymous user) access your application.

asp.net tips and tricks

Tue, 18 Aug 2009 14:49:24 +0000

How to get the username in a web app

Four steps to achieve it:

Use the following code to get the username in your application:

string user = User.Identity.Name.ToString();

Modify your web.config file to include the identity and the authentication tags:

<system.web>        
        <identity impersonate="true" />
        <authentication mode="Windows"/>
</system.web>

In IIS right click your application and select Properties. Go to the Directory Security tab. Click Edit under Authentication and Access Control. Uncheck Enable anonymous access and check Integrated Windows authentication. Click Ok to save your changes.
Open Windows Explorer, go to your application folder and modify permissions to allow your users (and not the IIS anonymous user) access your application.

Is beauty better than functional?

Sun, 08 Mar 2009 04:42:13 +0000

what do you think?

how many times we find ourselves trying to sell a good project that, because of its ugly look, ends in the garbage bin? Do you think an engineer should have some lessons on aesthetics? art? or leave that right minded work to the guy who used to be in ballet lessons at the university?

Tabs, Shortcuts and Internet Explorer

Thu, 05 Feb 2009 21:34:50 +0000

Have you read the information that shows up when you click the “new tab” button in IE? I think I did it once when I tried for the first time this tabbed IE, and never took a look at it again. Until yesterday. I just read it and surprised me because it contains a useful list of shortcuts for managing tabs. Many of them remind me the way Opera works, but there are a few new.

About this new year…

Mon, 12 Jan 2009 18:26:21 +0000

Hello all.

Since November I have been using the Microsoft 2008 Express Suite. Nice suite, but a big change since these last months I was only on the Java side. C# is one of those languages you can easily fall in love with.

Most of the applications I’m developing are for web, and it has been a great opportunity to use some of the DHTML libraries I’ve found on the web to create those new fancy interfaces. From accordions to drag and drop everything seemed so nice… until I faced the challenge to create a full Outlook-like calendar. I have been three or four days testing different libraries, and I’m afraid I will have to create it from the ground up. I’m very lazy for JavaScript programming… and specially if I have to integrate it with an existing library, including objects and events and all that stuff… uff, anyway… I think it’s time to start programming… or pushing the creative neuron further… 😛

Dilbert

Fri, 17 Oct 2008 16:04:11 +0000

I love Dilbert!

Firefox cannot load "localhost", while IE can

Sun, 24 Aug 2008 17:56:55 +0000

I installed IIS on a reformatted computer and when trying to access the home page using Firefox I was asked for my username and password. After many tries and permission checkings (check this first!) I used IE and it worked€¦ I googled a little bit and found this solution:

Open up Firefox and type about:config in the url field
In the Filter Type in ntlm
Double click €œnetwork.automatic-ntlm-auth.trusted-uris€ and type in localhost and hit enter

Windows Tips

Sat, 23 Aug 2008 22:01:23 +0000

Security Tips – How to turn off autoplay

Disc autoplay is a Windows feature that lets you execute a disc’s content when you insert it. Though this can be comfy, it presents a security threat for our systems since computer viri may reside in discs infecting all computers as they are inserted. To turn off the autoplay feature:

Go to Start > Run and type:

gpedit.msc

Press the Run button.</li> 

  * A window will pop-up. Go to Computer Configuration > Administrative Templates > System and change to Enable the _Turn off Autoplay_ option:

Installing a PDF print server on Ubuntu Server

Sat, 09 Aug 2008 03:09:03 +0000

This article was originally written for Ubuntu 7, but we now know it works for Ubuntu 10 as well. Thanks Shooda!

To start, install the CUPS service and CUPS-PDF files:

sudo apt-get install cupsys sudo apt-get install cups-pdf

Now configure CUPS to allow remote administration: sudo nano /etc/cups/cupsd.conf Modify the port where CUPS listens from:

Listen localhost:631

to:

Listen 631
Listen /var/run/cups/cups.sock
Listen 192.168.1.1:9100

The 192.168.1.1:9100 address allows you to connect to CUPS using the server’s network interface (192.168.1.1) on port 9100. I chose that port because that is the default port for HP printers (you can use the default port 631). Also modify these options to match the ones here:

Server Upgrade

Mon, 26 May 2008 21:46:56 +0000

Last sunday I upgraded my website software… phew!, It was a long task, but final result was very pleasant :-). Right now it’s running on WordPress 1.5. Very nice. One major change was the use of subdomains instead of subdirectories. I pretend to keep all blogs cleaner by putting each one in its own subdomain space. The price is some broken links on the net ;-)…

My papaya tree

Sun, 04 May 2008 22:28:06 +0000

This tree is in my garden… yummi, yummi

Logo contest and Xara

Sun, 04 May 2008 22:22:14 +0000

Two months ago I designed this logo for an internal company product contest. I didn’t win, but I learned a lot. Xara made the work very simple, and well… hope you like it as much as I do…

Ubuntu 8.04

Sun, 04 May 2008 22:05:31 +0000

Ubuntu 8.04 was released last week. This release includes features like:

Firefox 3 Beta 5: Web browser
Desktop Effects enabled by default: Window shadows, wobbling, animations, desktop on a 3D cube, transparency and a lot more.
Gnome 2.22: Window manager
Open Office 2.4: Office productivity suite.
PDF printer… and a lot more.

More information on ubuntu.com and gnome.org

On Polyominoes

Sun, 04 May 2008 21:17:48 +0000

Three weeks ago I had to work on polyominoes for a final project. Since I had to program an enumeration quickly, I wanted to find a simple algorithm to do it. Well, my search was hard. I barely found information on enumeration algorithms and read the work of many people including Redelmeier, Knuth and Ares RibÃ³. I chose to go the Redelmeier way because of the short time to complete the task. Here you can find part of my work, as well as some documents that explain more on this topic.

It’s official…

Sun, 27 Apr 2008 19:04:25 +0000

Ok, first time was fun, but now I hate it… I have deleted about 1000 spam comments in about a week… suggestions accepted…

117 comments…

Mon, 21 Apr 2008 19:39:34 +0000

Hey!, today while checking the comments for my site I found the amazing quantity of 117 comments… all of them spam! hahaha… this is a new record!

First rain since september

Mon, 14 Apr 2008 14:42:15 +0000

Finally, after six months it was so heavy. This is my garden covered by hail.

Solaris

Tue, 26 Feb 2008 04:18:36 +0000

How to change the screen resolution of Solaris 10 running in vmware

First you must install the vmware tools on your virtual machine.
Edit your xorg.conf file:

vi /etc/X11/xorg.conf

Under the section “Monitor” put a number sign (#) in front of all those screen resolutions you don’t want.
Save your file, log off and log on again.

What The GIMP needs

Sun, 10 Feb 2008 21:55:03 +0000

Photoshop is one of those so popular applications often missed in the Linux world. Ok, ok, the GIMP is there, but you have to learn to use it. Even moving a simple selection around becomes a hard to accomplish task. This makes me think, about all that people who has spent so many hours learning Photoshop. The solution: programming an interface very similar to Photoshop. And I mean, get the same keyboard shortcuts, menus, get an MDI interface, arrange tools in a similar way, etc.

Oracle XE on Ubuntu

Sat, 09 Feb 2008 02:33:15 +0000

Do you want to know how to set up Oracle? It is pretty simple and this tutorial will take you step by step through the installation process.

Installing Oracle XE on Ubuntu.

Installing Oracle XE on Ubuntu

Sat, 09 Feb 2008 02:24:06 +0000

My first encounter with Oracle was back in 2001. It was installed on a Windows 2k test server. We worked in a one year long project and I had enough time to learn about it. I just remember having encountered feelings. SQL was very pleasant: the CASE keyword was not part of my daily queries so I found it extremely useful to do rows to columns conversions. Text functions helped us implement all our crazy ideas for a search engine. And migration to production (a Solaris server) was completely painless. On the other side, it was a resource hog: running Oracle was the only thing test server could execute at a time and getting a working TNS configuration was a hard task. After that, I never considered again Oracle for my personal projects, because of its high price and hardware requirements. Until now.

Back from the hospital…

Sun, 03 Feb 2008 17:13:58 +0000

Hey there!, I’m back after a week in the hospital. Must say I really missed the Internet. My recommendation: don’t skip any meal! Always make time to eat and enjoy every food. According to some Japanese ideals, you should enjoy each bite and let your body shake to the flavors mix. After all, this week was just a reminder to keep my life in balance…

WebDAV Server is up and running!

Wed, 16 Jan 2008 00:49:04 +0000

I’m really excited about WebDAV! It just works! This is a tutorial I wrote:

https://andres.jaimes.net/setting-up-a-webdav-server/

Some minor issues are pending, but I’ll keep you posted.

Happy new year!!!

Setting up a WebDAV server

Wed, 16 Jan 2008 00:18:37 +0000

Do you want to install a WevDAV server? This article is for you.

What is WebDAV?

WebDAV is a protocol that lets you read and write files on the web almost as if you were accessing local files. You can create folders and files, as well as rename them, delete them and perform most common operations on them.

It stands for Web-based Distributed Authoring and Versioning. Since WebDAV is an extension to the HTTP protocol, you can still use features like security during file transfers (via HTTPS) or password protection on files and folders on the server.

UML: Association, Aggregation and Composition

Tue, 11 Dec 2007 03:33:19 +0000

This seems like the neverending story, and because I’m tired of it I want to share my understanding:

Association: Used when one instance should send a message to another instance. There’s no a whole / part relationship. In Java this can be an instance calling another instance’s methods. Examples of this can be a Customer and its persistance mechanism (DAO – data access object). They just send messages between each other.
Aggregation: Used to represent a whole / part relationship. The creation and destruction of child objects is not controlled by their parent. For example, a Binder and its sheets. You can destroy your binder and save your sheets for later usage… or for another binder.
Composition: Like an aggregation but the life span of child objects is controlled by their parent. For example, a Notebook and its sheets… If you create a notebook, you need to create sheets to fill it with. If you destroy your notebook you will destroy all your sheets. You know you have a composition when you no longer need the child objects once the parent has been destroyed.

Quotes…

Fri, 07 Dec 2007 20:26:28 +0000

The following are some nice quotes I’ve got from fortune cookies or my mind:

You can have, do or be whatever you want
Good sense is the master of human life
All decisions you make today will be most fortunate
You will be fortunate in everything you put your hands to
Today’s hardship leads to rewards in later life
Make a wish, it might come true

and for my spanish readers, here they are:

Oracle XE & PHP

Tue, 04 Dec 2007 23:44:52 +0000

Have you ever tried to access an Oracle database from PHP? Well, if you are a newbie (like me) this is a great manual that will take you from PHP compilation to XML generated results:

Download: The Underground PHP and Oracle Manual
By Christopher Jones and Alison Holloway

The book includes:

PHP Oracle Extensions
Installing Oracle Database 10g Express Edition
Using Oracle Database 10g
Installing Apache HTTP Server
Installing PHP
Connecting to Oracle Using OCI8
Executing SQL Statements with OCI8
Using PL/SQL with OCI8
and much more…

PHP

Fri, 30 Nov 2007 22:36:58 +0000

Connecting to a Local Oracle Database

This is a small but useful example:

<?php
$c = oci_connect('hr', 'hr', '//localhost/XE');
$s = oci_parse($c, 'select city from locations');
oci_execute($s);
while ($res = oci_fetch_array($s)) {
    echo $res['CITY'] . "<br>";
}
oci_close($c);
?>

Prior to use this example you must enable the hr user. To learn how to configure PHP to access Oracle databases check my Linux Console page.

Source: http://www.oracle.com/technology/tech/php/pdf/underground-php-oracle-manual.pdf

Ubuntu 7.10 Released

Tue, 06 Nov 2007 22:11:53 +0000

Among others, this new release of Ubuntu features:

3D Screen effects enabled by default: This is soooo cool! Plus, right click on your desktop, select Change Desktop Background, select Visual Effects and click on Extra, now go move a Window.
Themes, backgrounds, fonts, toolbars and visual effects have all been consolidated into a single form.
Desktop search: Quick search all your files, web, email, etc.
Pidgin: New name for the Gaim Internet Messenger, it features more icons 😉 and MSN icons are now shown for all your contacts.
User Switch button: Just click on it and switch among mom, dad or kids!

Got Web 2.0?

Wed, 22 Aug 2007 23:03:47 +0000

Ajax Hacks takes you step by step through an 80 tips journey going from the very basics – how to GET or POST – to advanced topics like performance tuning, caching and web services interaction.

AJAX Hacks by Bruce Perry
ISBN: 0-596-10169-4

Raise your hand!

Mon, 20 Aug 2007 19:34:15 +0000

Two days ago, while surfing a gov’s page, I got stuck at the very last step of a report generator. I right clicked the page, looked for a link and see the problem: an tag with a classid parameter. That object referenced a PDF file. And because the problem could be fixed by adding a simple link, I decided to give them a call. A lady answered the phone and listened carefully to my request. Kindly accepted to pass my suggestion to the IT department, where an IT Specialist would call me back. Very easy huh? So, why I had not tried that before? How many websites in the world, eager to get fixed, to attract new viewers, are just wating for a call? I’m sure many people do it, but from now on, guys count on me. I want to add my vote so all my favorite websites work on my favorite operating system. The more we are, the easier things will change. We’re just waiting for you.

Skype

Tue, 07 Aug 2007 17:23:07 +0000

How to Install Skype in Ubuntu

I just downloaded it and have to tell you it works great.

Download installer from Skype website
Double click and install downloaded file (you will need admin privileges)
Once installed you will find it under Applications -> Internet

If you get a “Problem with Audio Playback” message when doing a Test Call:

In Skype, go to Options -> Sound Devices and change “Sound Out” to something else than “Default device”, in my case I selected VIA 8237. Important: before changing this option when I pushed the “Make a test sound” button I could hear the test sound, after changing to VIA 8237 that button stopped working, but Skype calls got fixed.

Something else you might want to check are your audio settings. The Volume Control located on the upper right corner of the screen by default controls master volume. If you want to adjust you microphone’s volume from there do this:

Interesting Facts

Mon, 23 Jul 2007 20:13:41 +0000

Lastname: Jaimes

Did you know…

Jaimes is patronymic from the spanish personal name Jaime?
Most Jaimes in the U.S. live in Texas?
Top five departure places to the U.S. are Germany, Sweden, Venezuela, Preussen and Ireland?
Oldest immigration record dates from Aug 20, 1872 and belongs to Marie C. Jaimes, who was born in Germany and departed to the U.S. from Liverpool, England?
Life expectancy for Jaimes is 50 years? (20 less than the average)

Source: http://www.ancestry.com/learn/facts/Fact.aspx?&fid=7&ln=jaimes&fn=

Linux Console

Mon, 23 Jul 2007 19:45:18 +0000

Update your computer

You can update your computer from the console by executing the following commands:

1apt-get update
2apt-get upgrade

Installing a PDF print server on Ubuntu 7 Server

This document is too long to be here, so I moved it here: Installing a PDF print server on Ubuntu 7 Server

ISO images

How to create an iso image:

1mkisofs -r -l -o dvd.iso source-folder/

How to burn a dvd image:

Ubuntu Feisty Fawn (7.04) desktop

Mon, 23 Jul 2007 19:20:08 +0000

Sweet…

Ubuntu Feisty Fawn 7.04
Controls: Clearlooks
Window Border: Clearlooks Alternative
Icons: Dropline Neu!

IIS tips and tricks

Mon, 23 Jul 2007 18:35:20 +0000

Running multiple versions of the .NET framework in IIS

When you install a new .NET framework in your IIS server some applications can stop working showing you the following error:

Server Application Unavailable

In the event viewer you will find this:

the same IIS process. Please use the IIS Administration Tool to
reconfigure your server to run the application in a separate process.

This happens because different .NET frameworks can run in the same server, but cannot share the same application pool, so, to solve this:

Recipes

Mon, 23 Jul 2007 17:50:28 +0000

Pizza

Pizza requires 67% hydration.

825g flour
7g yeast
17g sea salt - try 12g next time.

mix

495g hot water
50g milk

heat to 40C degrees

30g olive oil

mix all previous ingredients

Pasta con brócoli

Ingredientes

Pasta
Brócoli
Ajo, finamente picado
Aceite de oliva
Queso parmesano
Sal, pimienta, guindilla triturada (hojuelas de chile)
Salmón u otra proteína (opcional)

Preparación

Cocer la pasta y el brócoli;
Sazonar el ajo con la guindilla en el aceite de oliva; agregar la proteína y cocer.
Una vez que todo esté cocido, picar el brócoli muy fino y verter junto con la pasta en el aceite de oliva; no descartar el agua de la pasta aún.
Agregar el queso, rayándolo finamente, y revolver; verificar la sazón;
Opcionalmente agregar una o más cucharadas de agua de la pasta para que no quede muy seco.

Spinach and Mandarin Salad (2 servings)

1/2 cup chopped peanuts
2 mandarines
2 cups deinfected and sliced spinach
1/2 cup de granos de elote cocidos

Dressing:

C# Tips and Tricks

Sun, 22 Jul 2007 18:23:01 +0000

Reading Outlook Contacts

Have you ever realized all you can do if Outlook contacts information were located into a database? If you have, this tip is for you. The first step is to take all that information out from Outlook so we can transform it into series of insert/update statements.

Start Microsoft Visual C# Express (you can download it for free from Microsoft’s site pending link).
Once downloaded and installed, create a new project and add Outlook’s library to it:
Go to Project -> Add Reference -> COM and select Microsoft Outlook 11.0 Object Library

Some words on Java, C# and C++

Sun, 22 Jul 2007 18:14:58 +0000

I have always considered myself a C++ guy. That was one of the first languages I learned. But, life has taken me through many different paths, and I have needed to learn others. It was seven years ago, when I tried my first cup of Java and I realized objects were a must: Why did I need to create an additional class to return a compound value? another file?, I could do a “one-liner” in C++. As time went by, I stopped thinking on certain optimizations like inline and char arrays and started thinking more seriously on blueprints. After all that time, I look back and realize those blueprints let me build lots of great projects. And market is not really interested on optimizations but on quick and effective development. So blueprints came into my life. Java gave me for many years what I needed but always had the feeling that it was not good enough for desktop applications. Then, SWT appeared. Finally a framework that felt rock solid… but only in Windows.

Mon, 01 Jan 0001 00:00:00 +0000

Your password must:

Be between 10-16 characters in length
Contain at least 1 lowercase and 1 uppercase letter
Contain at least 1 number (0–9)
Contain at least 1 special character (!@#$%^&()'[]"?+-/*)