This section gives a high level comparison between the new JSR 168 Portlet API and the IBM Portlet API. First, it covers the concepts that are similar; then, it explains some of the differences between the two.
The following concepts are very similar in JSR 168 and the IBM Portlet API.
Both support the basic portlet modes: Edit, Help, and View.
The config mode is optional in the JSR 168. The other optional JSR 168 modes (About, Edit_defaults, Preview, Print) are not supported by the IBM Portlet API.
These window states are supported: Maximized, Normal, and Minimized.
The Solo window state is only supported by the IBM Portlet API.
The lifecycle life cycle is the same: init, process requests, destroy.
Request processing is divided into an action phase for processing user actions and a render phase for producing the markup.
Both support creating URLs pointing to the portlet or to a resource.
Servlets and JSPs can be included in the portlet.
Portlets can store transient information that should span requests in a session.
Portlet application packaging
Both package portlet applications as WAR files with an additional deployment descriptor called portlet.xml.
The portlet.xml format differs.
The portlet can support expiration based caching.
The APIs use different mechanisms to implement this functionality.
The JSR 168 and the IBM Portlet API differ in the following ways.
IBM Portlet API
Portlet application entities
Lets you define an abstract portlet application and different instance of this portlet application as concrete portlet applications via the deployment descriptor. This allows reusing settings of the abstract portlet application and only overwriting the parts that are unique for each concrete portlet application.
The deployment descriptor follows the web.xml deployment descriptor and defines one portlet application and the portlet definitions for this application.
There is one portlet object instance per portlet configuration in the Web deployment descriptor. There may be many PortletSettings objects parameterizing the same portlet object according to the Flyweight pattern, provided on a per-request basis. Changes in the PortletSettings apply to all portlet instances of this concrete portlet. The user can also have personal views of concrete portlets that are rendered using the PortletData for customization of the output.
PortletSettings and PortletData are merged into one object called PortletPreferences.
The request/response object that the portlet receives in the render call is the same as the one received in the action call.
In the JSR 168 these are two different objects.