Portal Integration

for certain modes. However, it should be noted that some HTML content (for example, loading the portal-wide Vaadin theme) is created by the portlet and not the servlet.

12.9. Vaadin IPC for Liferay

Portlets rarely live alone. A page can contain multiple portlets and when the user interacts with one portlet, you may need to have the other portlets react to the change immediately. This is not normally possible with Vaadin portlets, as Vaadin applications need to get an Ajax request from the client-side to change their user interface. On the other hand, the regular inter-portlet communication (IPC) mechanism in Portlet 2.0 Specification requires a complete page reload, but that is not appropriate with Vaadin or in general Ajax applications, which do not require a page reload. One solution is to communicate between the portlets on the server-side and then use a serverpush mechanism to update the client-side.

The Vaadin IPC for Liferay Add-on takes another approach by communicating between the portlets through the client-side. Events (messages) are sent through the LiferayIPC component and the client-side widget relays them to the other portlets, as illustrated in Figure 12.5, “Vaadin IPC for Liferay Architecture”.

Figure 12.5. Vaadin IPC for Liferay Architecture

Vaadin IPC for Liferay uses the Liferay JavaScript event API for client-side inter-portlet communication, so you can communicate just as easily with other Liferay portlets.

Notice that you can use this communication only between portlets on the same page.

Figure 12.6, “Vaadin IPC Add-on Demo with Two Portlets” shows Vaadin IPC for Liferay in action. Entering a new item in one portlet is updated interactively in the other.

Vaadin IPC for Liferay

335

Portal Integration

Figure 12.6. Vaadin IPC Add-on Demo with Two Portlets

12.9.1. Installing the Add-on

The Vaadin IPC for Liferay add-on is available from the Vaadin Directory as well as from a Maven repository, as described in Chapter 17, Using Vaadin Add-ons.

The contents of the installation package are as follows:

vaadin-ipc-for-liferay-x.x.x.jar

The add-on JAR in the installation package must be installed in the WEB-INF/lib directory under the root context. The location depends on the server - for example in Liferay running in Tomcat it is located under the webapps/ROOT folder of the server.

doc

The documentation folder includes a README.TXT file that describes the contents of the installation package briefly, and licensing.txt and license-asl-2.0.txt, which describe the licensing under the Apache License 2.0. Under the doc/api folder is included the complete JavaDoc API documentation for the add-on.

vaadin-ipc-for-liferay-x.x.x-demo.war

A WAR containing demo portlets. After installing the add-on library and compiling the widget set, as described below, you can deploy the WAR to Liferay and add the two demo portlets to a page, as shown in Figure 12.6, “Vaadin IPC Add-on Demo with Two Portlets”. The source of the demo is available at dev.vaadin.com/svn/addons/IP- C f o r L i f e r a y / t r u n k / [http://dev.vaadin.com/svn/addons/IPCforLiferay/trunk/demo/src/com/vaadin/addon/ipcforliferay/demo/].

The add-on contains a widget set, which you must compile into the Vaadin widget set installed in the portal.

336	Installing the Add-on