Understanding Liferay Faces Bridge

The Liferay Faces Bridge enables you to deploy JSF web apps as portlets without writing portlet-specific code. It also contains innovative features that make it possible to leverage the power of JSF 2.x inside a portlet application.

Liferay Faces Bridge is distributed in a .jar file. You can add Liferay Faces Bridge as a dependency to your portlet projects, in order to deploy your JSF web applications as portlets within JSR 286 (Portlet 2.0) compliant portlet containers, like Liferay Portal 5.2, 6.0, 6.1, 6.2, and 7.0.

The Liferay Faces Bridge project home page can be found here.

To fully understand Liferay Faces Bridge, you must first understand the portlet bridge standard. Because the Portlet 1.0 and JSF 1.0 specs were being created at essentially the same time, the Expert Group (EG) for the JSF specification constructed the JSF framework to be compliant with portlets. For example, the ExternalContext.getRequest() method returns an Object instead of an javax.servlet.http.HttpServletRequest. When this method is used in a portal, the Object can be cast to a javax.portlet.PortletRequest. Despite the EG’s consciousness of portlet compatibility within the design of JSF, the gap between the portlet and JSF lifecycles had to be bridged.

Portlet bridge standards and implementations evolved over time.

Starting in 2004, several different JSF portlet bridge implementations were developed in order to provide JSF developers with the ability to deploy their JSF web apps as portlets. In 2006, the JCP formed the Portlet Bridge 1.0 (JSR 301) EG in order to define a standard bridge API, as well as detailed requirements for bridge implementations. JSR 301 was released in 2010, targeting Portlet 1.0 and JSF 1.2.

When the Portlet 2.0 (JSR 286) standard was released in 2008, it became necessary for the JCP to form the Portlet Bridge 2.0 (JSR 329) EG. JSR 329 was also released in 2010, targeting Portlet 2.0 and JSF 1.2.

After the JSR 314 EG released JSF 2.0 in 2009 and JSF 2.1 in 2010, it became evident that a Portlet Bridge 3.0 standard would be beneficial. In 2015 the JCP formed JSR 378) which is defining a bridge for Portlet 3.0 and JSF 2.2. There are also variants of Liferay Faces Bridge that support Portlet 2.0 and JSF 1.2/2.1/2.2.

Liferay Faces Bridge is the Reference Implementation (RI) of the Portlet Bridge Standard. It also contains innovative features that make it possible to leverage the power of JSF 2.x inside a portlet application.

Now that you’re familiar with some of the history of the Portlet Bridge standards, you’ll learn about the responsibilities required of the portlet bridge.

A JSF portlet bridge aligns the correct phases of the JSF lifecycle with each phase of the portlet lifecycle. For instance, if a browser sends an HTTP GET request to a portal page with a JSF portlet in it, the RENDER_PHASE is perfomed in the portlet’s lifecycle. The JSF portlet bridge then initiates the RESTORE_VIEW and RENDER_RESPONSE phases in the JSF lifecycle. Likewise, when an HTTP POST is executed on a portlet and the portlet enters the ACTION_PHASE, then the full JSF lifecycle is initiated by the bridge.

lifecycle-bridge.png

Figure 1: The different phases of the JSF Lifecycle are executed depending on which phase of the Portlet lifecycle is being executed.

Besides ensuring that the two lifecycles connect correctly, the JSF portlet bridge also acts as a mediator between the portal URL generator and JSF navigation rules. JSF portlet bridges ensure that URLs created by the portal comply with JSF navigation rules, so that a JSF portlet is able to switch to different views.

The JSR 329/378 standards defines several configuration options prefixed with the javax.portlet.faces namespace. Liferay Faces Bridge defines additional implementation-specific options prefixed with the com.liferay.faces.bridge namespace.

Liferay Faces Bridge is an essential part of the JSF development process for Liferay Portal.

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