[jboss-dev-forums] [Design of AOP on JBoss (Aspects/JBoss)] - Re: Reimplementing ClassPools for AS

[alesj]

"kabir.khan at jboss.com" wrote : 
  | Does a module represent a jar, thus meaning import everything from that jar?
  | 
I wouldn't call it 'import everything from that bundle'.
It's more like a plain bundle dependency, where you trust that bundle to have the packages/classes you need.
e.g. you know you're using Hibernate, so instead of doing every Hibernate import,
you just say I need Hibernate module, as you know that the Hibernate stuff you use it's gonna be there

"kabir.khan at jboss.com" wrote : And is package  more fine-grained, meaning only import these packages from that jar?
  | 
Yup, exactly.
It's when you need more fine-grained dependencies.

"kabir.khan at jboss.com" wrote : 
  | Whatever the answer, I suppose the Module/Package difference would also apply to the capabilities?
  | 
Module capabilities are filtered.
e.g. VFSDeploymentClassLoaderPolicyModule

  |       // We have a module capability
  |       Object version = getVersion();
  |       Capability capability = factory.createModule(getName(), version);
  |       capabilities.add(capability);
  |       
  |       // Do we determine package capabilities
  |       ClassFilter included = getIncluded();
  |       ClassFilter excluded = getExcluded();
  |       ClassFilter excludedExport = getExcludedExport();
  |       ExportAll exportAll = getExportAll();
  |       if (exportAll != null)
  |       {
  |          Set<String> exportedPackages = PackageVisitor.determineAllPackages(roots, excludedRoots, exportAll, included, excluded, excludedExport);
  |          for (String packageName : exportedPackages)
  |          {
  |             capability = factory.createPackage(packageName, version);
  |             capabilities.add(capability);
  |          }
  |       }
  |       
  |       return capabilities;
  | 

Package capabilities would normally come from jboss-classloading.xml,
an explicit definition -> capabilities/package/name+version ...

"kabir.khan at jboss.com" wrote : 
  | Also, what is UsesPackageRequirement?
  | 
It's when some export depends on some other bundle/api.

  | A comma-separated list of package names that are used by the
  | exported package. Note that the use of a comma in the value requires it
  | to be enclosed in double quotes. If this exported package is chosen as an
  | export, then the resolver must ensure that importers of this package wire
  | to the same versions of the package in this list.
  | 
  | ...
  | 
  | Classes can depend on classes in other packages. For example, when they
  | extend classes from another package, or these other classes appear in
  | method signatures. It can therefore be said that a package uses other packages.
  | These inter-package dependencies are modeled with the uses directive
  | on the Export-Package header.
  | For example, org.osgi.service.http depends on the package javax.servlet
  | because it is used in the API. The export definition of the
  | org.osgi.service.http must therefore contain the uses directive with the
  | javax.servlet package as its value.
  | 
So you need to import that, in order to resolve properly,
as 'uses' enforces a transitive dependency on exact version.

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