Spring Roo (Milestone2) is the newest Spring brain child. This time however not a (integration) framework, but a real application generation tool.

Using a command line tool (Yes really) you not only tell Roo to generate code for you, but you also use it to modify your generated code.
For example with a simple:

create project -topLevelPackage nl.ordina.compcomp

a project is created.

And with a:

new persistent class jpa -name ~.domain.Competence

a JPA class is generated.

Adding attributes to the JPA class is also done wit a command like:

add field string description

Web interface generation is done by:

new controller automatic ~.web.CompetenceController

In short this is it. A web application with CRUD functionality. The fun part is however the code that is generated. One statement from the Spring Roo website that really intrigued me, is the ability of Roo to once generate your application and the allow you to continue without using Roo. How did the solfe the generation gap and how is it that I can continue developing the application without Roo.

So lets see what Roo has generated:

package nl.ordina.compcomp.domain;
 
import javax.persistence.Entity;
import org.springframework.roo.addon.entity.RooEntity;
import org.springframework.roo.addon.javabean.RooJavaBean;
import org.springframework.roo.addon.tostring.RooToString;
 
@Entity
@RooEntity
@RooJavaBean
@RooToString
public class Competence {
 
private String description;
}

Thats it. But you say where is the rest then. Or do they have some fancy runtime framework that acts on the beautiful annotations. Well yes and no. Besides the java class a number of AspectJ files are also generated. And these files contain the extra generated code. The generation gap is solved by adding functionality using AOP. The aspect files are generated over and over again. The java class file however is only generated once and can be modified by the programmer.

If you like to continue without Roo, simply tell it to Roo. What will happen is that the Roo annotation are removed from your java files and the Aspects will be merged into your class. At that point the Roo dependency is no longer needed.

Is this the way to go? Who knows must tell. I don’t. The code is still in Milestone phase so it is not written in stone and may contain some bugs or missing functionality. The reasoning behind Roo and some implementation however choices I personally find interesting.

What do you think?

Dit bericht is gepost op 22 June 2009 om 7:44 am uur en is geplaatst in Algemeen. Je kunt alle reacties op dit bericht volgen via de RSS 2.0 feed. Je kunt een reactie achter laten of trackback vanaf je eigen site.