Question

I have a Grails Application AppA. And I am planning to create a new Grails Application AppB, wherein AppB practically uses the same services and models of AppA.

How should I approach that?

1. Extract a Grails Application AppC which would have the common services and expose that service as a remote/web/rest service?
2. Extract a Groovy project ModC that will be a jar containing the common services and models and have AppA & AppB depend on ModC?
3. Just git clone and cherry-pick every now & then?
4. Other suggestions?

Note that AppA have some lazy-loaded relationship invocations (i.e. entity1.entity2.entity3.propName) & GORM invocations (i.e. Entity1.get(1L)) from the presentation layer (controllers & views) as well. Although I can probably push some of them back to the services, I’m concerned about the refactoring effort to have the relationship invocations from the view remain intact (i.e. I would need to eager loaded some associations, or create Data Transfer Objects)

Answer 1

The Grails way to share common functionalities, utilities and whatnot is to make a plugin that encapsulates those and install it to both projects.

A plugin can contain anything you can put in a regular Grails app — i.e. Models, Service, Views, Controllers, config files, resources under web-app etc.

You can then either release it to an internal svn repository or just use it with package-plugin

Edit:

One way to do it while you are constantly updating the code is to have it as an inline plugin. So remove the plugin from your application.properties and add:

grails.plugin.location."name-of-plugin" = "/path/to/plugin/dir" // or "../plugin/"

This removes the necessity of reinstalling the plugin all the time. But this is for development time only.