Running JNDI and JPA Without J2EE Container

We wanted to test some JPA code with as simple setup as possible. The plan was to use only Java and Maven, without an application server or other J2EE container.

Our JPA configuration needs two things to run successfully:

• database to store data,
• JNDI to access the database.

This post has two parts. First part shows how to use standalone JNDI and an embedded in-memory database in test. Remaining chapters explain how the solution works.

JavaScript Testing with JSTestDriver

Js-test-driver is an open source JavaScript unit tests runner written in Java. The project was started at Google and is under active development. It is available under Apache License 2.0 license.

Js-test-driver is able to run from command line and reports results to the standard output. As a result, it is possible to fully automate JavaScript tests and run them on a continuous integration server.

Additionally, js-test-driver comes with IntelliJ IDEA plugin and Eclipse plugin. Of course, Eclipse plugin is compatible with Aptana Studio. If you use one of these IDEs, you can run tests directly from IDE and see progress and results in a view. It is very similar to java jUnit plugin.

Apache Shiro Part 3 - Cryptography

Besides securing web pages and managing access rights Apache Shiro does also basic cryptography tasks. The framework is able to:

• encrypt and decrypt data,
• hash data,
• generate random numbers.

Shiro does not implement any cryptography algorithms. All calculations are delegated to Java Cryptography Extension (JCE) API. The main benefit of using Shiro instead of what is already present in Java is ease of use and secure defaults. Shiro crypto module is written in higher abstraction level and by default implements all known best practices.

Project Report - JSSokoban

I have never worked on bigger JavaScript project and I have never worked with 3D. And I never wrote a game. Better late than never, I will create 3D game in JavaScript. The whole project is less ambitious than it sounds, I will create a Sokoban clone.

Sokoban is a turn-based puzzle with simple rules and graphics. The player navigates a little robot through a warehouse. The warehouse contains walls, wooden boxes and destinations.

MapReduce Questions and Answers

With all the hype and buzz surrounding NoSQL, I decided to have a look at it. I quickly found that there is not one NoSQL I could learn. Rather, there are various different solutions with different purposes and trade offs. Those various solutions tend to have one thing in common: processing of data in NoSQL storage is usually done using MapReduce framework.

Search on MapReduce found various scattered blog posts, some universities courses pages and one book that seems to contain almost everything other sources did.

This post contains MapReduce questions and answers based on the book. Basically, if I would be a student, this is what I would have made as a test preparation notes. If I would be a teacher, this is what I would ask on the exam.

ANTLR Tutorial - Expression Language

ANTLR tool is useful any time you need to create compiler, interpreter or parser of your own language. It takes so called grammar file as an input and generates two classes: lexer and parser.

This post explains what is lexer, what is parser and how to write grammar files to generate them. In the end of the post, you will be able to create a compiler into abstract syntax tree for any simple programming language.

Our example project, a boolean expression language, is written in Java and available on Github. Besides that, everything explained in this post is language independent. Grammar files are the same in all languages.

ANTLR Tutorial - Hello Word

Antlr stands for ANother Tool for Language Recognition. The tool is able to generate compiler or interpreter for any computer language. Besides obvious use, e.g. need to parse a real 'big' programming language such as Java, PHP or SQL, it can help with smaller, more common tasks.

It is useful any time you need to evaluate expressions unknown at compile-time or to parse non-trivial user input or files in a weird format. Of course, it is possible to create custom hand made parser for any of these tasks. However, it usually takes much more time and effort. A little knowledge of a good parser generator may turn these time-consuming tasks into easy and fast exercises.