I would like to share the data access portion of my grails app (Grails domain classes and services) with another grails app. One is a standard client facing web app, the other (not yet written) will be for periodic background tasks such as reminder emails and such using the Quartz plugin or similar, where the UI will just be for statistics/control for internal users.
I do not want this all bundled in one Grails application because I want to be able to scale them and run them on different machines. What is the proper way to do this? I have accomplished this in the past in more legacy Java web applications by bundling the shared data access classes into a .jar and including them where needed in multiple apps, but I’m not sure if this is the right approach for Grails.
I’ve considered a full blown service oriented architecture where a third grails application is responsible for all data access and the two described do all their data access through REST calls to this service app, but this is out of scope for the short term since the client facing webapp is already written.
Usually this is done via plugins. Create your domain classes, services, controllers and even default gsp’s that you want to share among apps and create them as a plugin. That way you can install them in any Grails app that requires that behavior.
I’ve done this with some generic accounting type behavior that is fairly common among apps I write like receivables, payables, etc.
One great thing is that you can write the plugin and test separately with a test data source and then when you install it into a Grails app it will use the apps data source. And it will have default gsp’s and controllers that give you a basic set of behavior that you can override in the actual app.