Application Programmer Interfact (API)

Repository

The Repository interface provides a simple protocol independent API against which a client can retrieve physical artifacts, artifact metadata, and composite objects derived from metadata information.

Get an artifact.

The getResource( Artifact artifact ) operation provides a simple protocol independent method to get a concrete url to a resource. The actual url returned to the client is a function of the repository implementation established at runtime. 

    /**
     * Get a resource url relative to the supplied artifact.
     * 
     * @param artifact the artifact describing the resource
     * @return the resource url
     */
    URL getResource( Artifact artifact ) throws RepositoryException;

Artifact Attribute Retrival.

The getAttributes operation provides support for the retrival of a set of attributes corresponding to metadata about an artifact. This information is used to construct higher level objecets such as classloaders based on dependencies declaring in metadata. 

   /**
    * Return the metadata of an artifact as attributes.
    * @param artifact the artifact
    * @return the attributes resolved relative to the artifact address
    * @exception RepositoryException if an error occurs while resolving
    *   artifact metadata attributes
    */
    Attributes getAttributes( Artifact artifact ) 
        throws RepositoryException;

Classloader creation.

Using matadata associated with an artifact, the repository can construct a component classloader tree that can be used in the subsequent deployment of compoents and applications. 

    /**
     * Creates a ClassLoader chain returning the lowest ClassLoader containing 
     * the jar artifact in the loader's path.  The dependencies of the argument 
     * artifact jar and an api, spi and implementation attribute on the jar and 
     * its dependencies are used to construct the ClassLoaders.
     * 
     * @param artifact the implementation artifact
     * @return the lowest ClassLoader in a chain
     * @throws RepositoryException if there is a problem caching and accessing
     * repository artifacts and reading their attributes.
     */
    ClassLoader getClassLoader( Artifact artifact )
        throws RepositoryException;

Classloader creation (using a parent).

This function is equivalent to the basic getClassloader operation except that it allows the declaration of the parent classloader to be used when constructing the new classloader chain. 

    /**
     * Creates a ClassLoader chain returning the lowest ClassLoader containing 
     * the jar artifact in the loader's path.  The dependencies of the argument 
     * artifact jar and an api, spi and implementation attribute on the jar and 
     * its dependencies are used to construct the ClassLoaders.
     * 
     * @param parent the parent classloader
     * @param artifact the implementation artifact
     * @return the lowest ClassLoader in a chain
     * @throws RepositoryException if there is a problem caching and accessing
     * repository artifacts and reading their attributes.
     */
    ClassLoader getClassLoader( ClassLoader parent, Artifact artifact )
        throws RepositoryException ;