As we recently discovered, a problem can arise with configuration when an application
is built with a different "mix" of services. For example: if you build the default
applications with default persistence, the references to default-persistent in the
configuration for, say, app-poll work just fine - they add the default security
records and all is well.
If, OTOH, you build for Hibernate, you'll have a problem, as these
"default-persistent" entries have no class defined for them, and the Keel container
will choke on startup as a result. Of course, you can go back and remove them all,
then put in the hibernate equivilants, but that's painful.
Instead, I'm trying a method that will allow certain configuration elements to be
skipped if a specific service is not selected. This works much like the Ant "if"
attribute - in fact, I used the "if" attribute to do it, for consistency. Then, you
could do something like this:
<default-persistent id="..." if="service.persist.default">
....
</default-persistent>
If you build with service.persist.default=true in your *-deploy.properties, this
configuration will be enabled as usual. If you do not have service.persist.default
set, it will be "pruned" from the configuration before the container sees it during
startup. Along similar lines, there is configuration in app-poll for the "Navigate"
application:
<nav.navigate id="nav.navigate">
<menu id="....">
... menu entries for poll ...
</menu>
</nav.navigate>
If you're *not* using Navigate (app.navigate) then this configuration will also
complain on startup, as nav.navigate's class is not found. You could now (with this
proposed feature) say:
<nav.navigate id="nav.navigate" if="app.navigate">
.... as before ....
And not have to worry about the specific deployment. If navigate is there, it's used.
If it's not, it's skipped.
One added bonus would be that it is then possible for a model (or another service) to
determine which services are available at runtime, before trying to access them - not
something needed a lot, but handy in some cases.
Anyone see a gotcha in this plan? If not, I'll test it and get it into CVS.
Regards,
Michael Nash
JGlobal Ltd
Next-Generation Web Application Development and Open Source Support
http://www.jglobal.com
Bahamas Commerce and Trade
Offshore eCommerce Hosting and Business Services
http://www.bahamascommerce.com
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