« Posts by Ant

Write a Stored Procedure in Postgres 8+

May 5, 2010 / posted in sql, Technobable / No Comments

Stored Procs

Sometimes as a developer we’re tasked with data intensive work like importing data into a database, cleaning up sets of incomplete records or transferring data from one table to another through some kind of filter. While our application would normally be in charge of creating and maintaining the data, sometimes we don’t want to end up writing an entire module or mini application to address these tasks. Since they’re data intensive, a stored procedure might be a good approach to take. Stored procedures are a type of program written using a more robust version of sql (structured query…

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*nix commands I can’t do without

February 13, 2010 / posted in Fedora / 10 Comments

Unix/Linux/*nix survival 101

Let me start with the obvious: I’m definitely not a unix guru by any means. I do however use it on a daily basis for basic build/development oriented tasks, so I know enough to get by. Since my friend just installed his first ever linux distribution (CentOS, Huzzah!), I thought I’d write something up on some common unix commands that help me get through the day.

grep [command flags] [search text] [filename]

grep (global | regular expression | print) is the file text search command. Give it a regular expression and it will print out…

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Transforming XML into MS Excel XML

February 9, 2010 / posted in xml / No Comments

MS Excel understands XML?

If you need to export xml to a Microsoft Excel friendly format, you could stress over the HSSF (Horrible Spread Sheet Format, for the uninitiated) format with apache’s POI framework or you could transform your xml into an format Excel understands. This approach will allow you to decorate your cells with stylized fonts and borders; what it will not allow you to do is create or add complex objects like charts, graphs or pictures. This xml format is a watered down version of excel. If you require the ability to embed images, graphs…

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Integrating Spring MVC 3.0 with JSR 303 (aka javax.validation.*)

February 8, 2010 / posted in Java / 39 Comments

Annotated POJO validation comes to a JDK near you!

The new annotated validation spec (jsr 303) is pretty slick, especially when used along side Spring MVC 3.0, and when backed by ejb3 entities. I’m pretty impressed with how easily it integrates with Spring MVC’s framework, and with how seamlessly error messages are passed to the form taglibs so they show up in your web forms.

I know some of you might argue that the current validation framework might not address complex validations, but after giving Hibernate’s reference implementation documentation a look, it seems interdependent validations are at least…

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Quartz Scheduled Jobs – v1.5.2

February 5, 2010 / posted in Java / 7 Comments

Java, XML, and cron driven scheduling made easy.

Projects here and there often need some kind of mechanism to schedule jobs at odd hours, or intervals. Quartz is a robust, flexible tool you can use to accomplish simple to complex job scheduling. There are a number of ways to use/configure quartz, but I’ve grown accustomed to using it with an xml based configuration. There are a few things we need to set up unfortunately, so there is a certain amount of plumbing we need to work out, but once that infrastructure is set up, its much less work…

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Ejb3 Basics: Deploying Message Driven Beans

February 2, 2010 / posted in Java, Jboss / 2 Comments

Farewell to lazy auto queue generation in JBoss 5

MDB’s were never so easy to deploy and manage when ejb3 first came out. In Jboss 4, all you have to do was annotate a class with @MessageDriven, sprinkle some meta data here and there, stick it in the oven and wham! Instant “I cant believe I made an MDB!?!” In Jboss AS 5 however, MDB queues are no longer automatically created for your application anymore on boot. An inspection of the MDB llifecycle illustrates why:

  1. MDB deploys
  2. No existing Topic/Queue
  3. Topic/Queue is automatically created
  4. MDB is

…

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Ejb3 basics: Entities

January 29, 2010 / posted in Java / No Comments

Entity Beans? Better than 2.1, I promise.

Ejb3 Entity beans are a type of enterprise java bean construct used to model data used by the ejb framework. The basic idea is to manipulate simple java objects, which represent in concrete terms your database data, and then have the framework handle as much of the plumbing as possible when you persist the data. Persisting means to store for later use in some data repository – usually some kind of database. By persisting these entities within the ejb framework we are able to abstract out tasks like updating a table and its…

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XML, Xalan, Endorsed dirs and &..

January 28, 2010 / posted in Jboss, Technobable / 3 Comments

So recently, we’ve been working on a project that makes use of OpenSAML. As it turns out OpenSAML required newer Xalan libraries (2.7.1 to be precise), the kind that don’t ship with the older incarnation of jboss we are using for the project – version 4.02. Some of you might be more familiar with the jboss system properties and will know there’s a property jboss used specifically to override the standard xml libraries that ship with the jdk/jre (entry in the console output bolded and marked with a *). Jboss will allow you to pass in…

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War deployment file structure

January 25, 2010 / posted in Java, Jboss / 1 Comment

What’s a war deployment, do I need my own army?

When it comes to deploying an web based application we have a few options on the table. Well only one really if you stick to J2EE standards, not counting Ear deployments which also deploy web apps via wars. Outside the world of J2EE though, it becomes a crap shoot based on the web framework you’re using. So what’s a war look like?

webapp.war
	|-- images/
	|   `-- banner.jpg
	|-- index.html
	|-- jsps/
	|   |-- public/
	|   |   `-- login.jsp
	|   `-- private/
	|       |-- application.jsp
	|

…

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Java, XML and XStream

January 22, 2010 / posted in Java, Technobable, xml / 9 Comments

What’s an object/xml serializaing/deserializaing library?

If you’ve never worked with an object/xml serializer and are considering writing your own from scratch, you may want to consider using a library like XStream. XStream is very good at moving java into xml and back. It allows a high level of control over how the xml can be organized and structured and even allows the user to create their own converters for even more flexibility.

But still, why use something like this when you can be perfectly happy writing your own data conversion scheme? The problem really boils down to…

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