public Extension(PluginDescriptor pDescriptor,
    String pExtensionPoint,
    String pId,
    String pExtensionClass,
    Configuration conf,
    PluginRepository pluginRepository) 
{
    fAttributes = new HashMap< String, String >();
    setDescriptor(pDescriptor);
    setExtensionPoint(pExtensionPoint);
    setId(pId);
    setClazz(pExtensionClass);
    this.conf = conf;
    this.pluginRepository = pluginRepository;
}

Parameters:

pDescriptor - a plugin descriptor

pExtensionPoint - an extension porin

pId - an unique id of the plugin

 public  void addAttribute(String pKey,
    String pValue) 
{
    fAttributes.put(pKey, pValue);
}

Adds a attribute and is only used until model creation at plugin system start up.

 public String getAttribute(String pKey) 
{
    return fAttributes.get(pKey);
}

Returns a attribute value, that is setuped in the manifest file and is definied by the extension point xml schema.

 public String getClazz() 
{
    return fClazz;
}

Returns the full class name of the extension point implementation

 public PluginDescriptor getDescriptor() 
{
    return fDescriptor;
}

return the plugin descriptor.

 public Object getExtensionInstance() throws PluginRuntimeException 
{
    // Must synchronize here to make sure creation and initialization
    // of a plugin instance and it extension instance are done by
    // one and only one thread.
    // The same is in PluginRepository.getPluginInstance().
    // Suggested by Stefan Groschupf < sg@media-style.com >
    synchronized (getId()) {
      try {
        PluginClassLoader loader = fDescriptor.getClassLoader();
        Class extensionClazz = loader.loadClass(getClazz());
        // lazy loading of Plugin in case there is no instance of the plugin
        // already.
        this.pluginRepository.getPluginInstance(getDescriptor());
        Object object = extensionClazz.newInstance();
        if (object instanceof Configurable) {
          ((Configurable) object).setConf(this.conf);
        }
        return object;
      } catch (ClassNotFoundException e) {
        throw new PluginRuntimeException(e);
      } catch (InstantiationException e) {
        throw new PluginRuntimeException(e);
      } catch (IllegalAccessException e) {
        throw new PluginRuntimeException(e);
      }
    }
}

Return an instance of the extension implementatio. Before we create a extension instance we startup the plugin if it is not already done. The plugin instance and the extension instance use the same PluginClassLoader. Each Plugin use its own classloader. The PluginClassLoader knows only own Plugin runtime libraries setuped in the plugin manifest file and exported libraries of the depenedend plugins.

 public String getId() 
{
    return fId;
}

Return the unique id of the extension.

 public String getTargetPoint() 
{
    return fTargetPoint;
}

Returns the Id of the extension point, that is implemented by this extension.

 public  void setClazz(String extensionClazz) 
{
    fClazz = extensionClazz;
}

Sets the Class that implement the concret extension and is only used until model creation at system start up.

 public  void setDescriptor(PluginDescriptor pDescriptor) 
{
    fDescriptor = pDescriptor;
}

Sets the plugin descriptor and is only used until model creation at system start up.

 public  void setId(String extensionID) 
{
    fId = extensionID;
}

Sets the unique extension Id and is only used until model creation at system start up.