extension.md

layout	class	title	summary
default	Project	-extension	A plugin that is loaded to its url, downloaded and then provides a header used instantiate the plugin.

/**
 * Add any extensions listed
 * 
 * @param list
 * @param rri
 */
@Override
protected void addExtensions(Set<Object> list) {
	//
	// <bsn>; version=<range>
	//
	Parameters extensions = new Parameters(getProperty(EXTENSION));
	Map<DownloadBlocker,Attrs> blockers = new HashMap<DownloadBlocker,Attrs>();

	for (Entry<String,Attrs> i : extensions.entrySet()) {
		String bsn = removeDuplicateMarker(i.getKey());
		String stringRange = i.getValue().get(VERSION_ATTRIBUTE);

		trace("Adding extension %s-%s", bsn, stringRange);

		if (stringRange == null)
			stringRange = Version.LOWEST.toString();
		else if (!VersionRange.isVersionRange(stringRange)) {
			error("Invalid version range %s on extension %s", stringRange, bsn);
			continue;
		}
		try {
			SortedSet<ResourceDescriptor> matches = resourceRepositoryImpl.find(null, bsn, new VersionRange(
					stringRange));
			if (matches.isEmpty()) {
				error("Extension %s;version=%s not found in base repo", bsn, stringRange);
				continue;
			}

			DownloadBlocker blocker = new DownloadBlocker(this);
			blockers.put(blocker, i.getValue());
			resourceRepositoryImpl.getResource(matches.last().id, blocker);
		}
		catch (Exception e) {
			error("Failed to load extension %s-%s, %s", bsn, stringRange, e);
		}
	}

	trace("Found extensions %s", blockers);

	for (Entry<DownloadBlocker,Attrs> blocker : blockers.entrySet()) {
		try {
			String reason = blocker.getKey().getReason();
			if (reason != null) {
				error("Extension load failed: %s", reason);
				continue;
			}

			URLClassLoader cl = new URLClassLoader(new URL[] {
				blocker.getKey().getFile().toURI().toURL()
			}, getClass().getClassLoader());
			Enumeration<URL> manifests = cl.getResources("META-INF/MANIFEST.MF");
			while (manifests.hasMoreElements()) {
				Manifest m = new Manifest(manifests.nextElement().openStream());
				Parameters activators = new Parameters(m.getMainAttributes().getValue("Extension-Activator"));
				for (Entry<String,Attrs> e : activators.entrySet()) {
					try {
						Class< ? > c = cl.loadClass(e.getKey());
						ExtensionActivator extensionActivator = (ExtensionActivator) c.newInstance();
						customize(extensionActivator, blocker.getValue());
						List< ? > plugins = extensionActivator.activate(this, blocker.getValue());
						list.add(extensionActivator);

						if (plugins != null)
							for (Object plugin : plugins) {
								list.add(plugin);
							}
					}
					catch (ClassNotFoundException cnfe) {
						error("Loading extension %s, extension activator missing: %s (ignored)", blocker,
								e.getKey());
					}
				}
			}
		}
		catch (Exception e) {
			error("failed to install extension %s due to %s", blocker, e);
		}
	}
}