Basic questions about bundles and features

["KARR, DAVID" <dk...@att.com>]

I have some likely basic questions about features and bundles, and the "features.xml" file.  I'm doing some work on an existing codebase, where I think much has been done to get things working, without complete understanding of the machinery.  I'd like to get an external perspective before I talk to other devs in the project.

Our build has a bunch of "api" and "impl" modules.  All of these modules use the "maven-bundle-plugin", to at least specify the list of packages to export.  Some of the "impl" modules have "features.xml" files, but not all of them.  None of the "api" modules have them.

Many of the "features.xml" files in the "impl" modules have patterns like this (this is in the "account-impl" module):
---------------------
  <feature name='account' version='${pom.version}'>
    <feature>base</feature>
    <bundle>mvn:com.att.detsusl/account-api/${pom.version}</bundle>   
    <bundle>mvn:com.att.detsusl/db-impl/${pom.version}</bundle>
    <bundle>mvn:com.att.detsusl/account-impl/${pom.version}</bundle>
    <bundle>mvn:com.att.detsusl/acs-impl/${pom.version}</bundle>
---------------------

There are a few things to note here.

First, this "account" feature depends on both the "account-api" and "account-impl" bundle, the latter of which is the bundle implemented in this module itself.  That doesn't seem to make any sense to me.  Second, it also depends on the "account-api" bundle.  There is no "features.xml" in that bundle.  If there was, would this be able to specify a dependency as a feature instead of a bundle?  What would be the implications of that?  This feature also depends on other impl bundles, instead of the features they are defined within.  Is there ever any reason to depend directly on the bundles, instead of the features?