Project directory structure

Object graph of "Discipline" class

*Note: The "..." means "Task nn"

Object graph of "Phase" class

How to get the "text" value of an XML element in GWT

Hibernating gPasma

In a nutshell, adding Hibernate to a GWT project consists in:

• Adding the Hibernate libraries (jars) to the classpath
• Adding your JDBC driver to the classpath
• Creating Object mappings (.hbm.xml files) between your Beans and DB tables
  
• Configuring Hibernate to use your DB and mappings (hibernate.cfg.xml)
• Configure Log4J (optional - log4j.properties)
• Creating GWT services that will use Hibernate to access the DB (aService.java, aServiceAsync.java, aServiceImpl.java)

This is the application stack for gPasma (or any GWT and Hibernate app):


The stack identified as 'GWT Services' actually uses the GWT and Hibernate APIs in order to persist the objects. GWT is used to traffic the objects between server and GUI (RPC calls) and Hibernate is used to manage DB sessions, threading and ultimately generating the DB specific calls.

This is a very simplified DB model for the application that will be implemented for this first Hibernate attempt:
The idea behind it is that a 'Process Model' contains 'Process Disciplines' that at their turn contain 'Tasks'. There might be many Process Models but they won't share the disciplines. This basically means that if if we want to generate a new Process Model from a previously existing one, we just copy all the Disciplines and Tasks to the new. Any modifications made only affect the new Process Model, leaving the previous untouched.

An Eclipse project using GWT and Hibernate should look similar to this (very ugly) image:


The items marked with an * are files that have to be changed/added when adding Hibernate to the project.

Using TortoiseCVS with eclipse

I find SVN (subversion) a version control system far superior to CVS. In order to try to go around some of it's limitations, I'm using TortoiseCVS.
The default connection method used by eclipse is incompatible with TortoiseCVS.
To be able to use both programs to manage code on the client side, some steps are necessary:

• Configure eclipse to use tortoise's SSH client
• Check out a fresh working directory (project)
• Configure Tortoise with ssh-keys so you don't need to give passwords all the time
• Generate the key with puttyGen
• Making pageant load the key
• Other page describing the procedure, used by winCVS

I sucessfully used the method described on the links above ( Generate... and Making...). For loading the keys in Pageant I use a DOS script. The file is named loadKeys.cmd. It expects the key and pageant.exe to be in the same folder; Its contents are as follow:

C:\sshKeys\pageant.exe C:\sshKeys\ssh2RSA.ppk

More Hibernate links

• Hibernate Home Page
• Good (and long) Hibernate article and tutorial
• Tutorial on building a simple app with Hibernate, Eclipse and MySQL/Postgress
• Hibernate page on Wikipedia
• Another tutorial on Hibernate