Network Deployment (Distributed operating systems), v8.0 > Develop and deploying applications > Develop Portlet applications > Assembling portlets


Portlet Uniform Resource Locator (URL) addressability

We can request a portlet directly through a Uniform Resource Locator (URL) to display its content without portal aggregation. The PortletServingServlet servlet registers each web application that contains portlets. It is similar to the FileServingServlet servlet of the web container that serves resources. The PortletServingServlet servlet supports direct rendering of portlets into a full browser page by a URL request.

We can invoke each portlet by its context root and name with the URL mapping / <portlet-name> that is created for each portlet. The context root and name has the following format: 

http://
<host>:
<port>/
<context-root>/
<portlet-name> For example,
 http://localhost:9080/portlets/TestPortlet1
The context root identifies the WAR file that contains the portlet. The portlet name uniquely identifies the portlet with a portlet application of a WAR file. The DefaultDocumentFilter servlet only supports HTML, UTF8 encoding and an extended URL form based on the basic URL form as shown above.

We can only display one portlet at a time using the PortletServingServlet servlet. To aggregate multiple portlets on the page, you need to use the aggregation tag library. Refer to the Portlet aggregation using JSP article for additional information.

Because a portlet only delivers fragment output whereas a servlet usually delivers document output, a mechanism is introduced to convert the fragment into a document, called the PortletDocumentFilter filter. By default, the PortletDocumentFilter filter only supports converting HTML. The conversion is implemented using a servlet filter before the PortletServingServlet servlet is initiated to return the portlet‘s content inside of a document. This default document servlet filter only applies to URL requests, not for includes or forwards using the RequestDispatcher method. We can create servlet filters to support other markups additional document servlet filters. Refer to the Converting portlet fragments to an HTML document article, for additional information.

The PortletServingServlet servlet does not persist portlet preferences in a XML file or database. It places the portlet preferences directly into a cookie to store the preferences persistently. Refer to the Portlet preferences article, for additional information on how to change this behavior.


Portlet URL syntax

We can add additional portal context such as portlet mode or window state. We can access the PortletServingServlet servlet by using a URL mapping that has the following structure: 

http://host:port/context/portlet-name [/portletwindow[/ver [/action |
 /resource[/id=custom-id][/cacheability]] [/mode] [/state] [rparam][/?name]]]
Any differing URL structure results in a com.ibm.wsspi.portletcontainer.InvalidURLException exception. Empty strings are not permitted as parameter values and creates an InvalidURLException exception. The following is a list of valid parameters:

http:// host:port/context/portlet-name

This is the minimum URL required to access a portlet. A default portlet window called ‘default’ is created. The portlet-name variable is case-sensitive.

/portletwindow

This parameter identifies the portlet window. We must set this parameter if you choose to add more portal context information to the URL.

/ver=major.minor

This optional parameter is used to define the version of the portlet API used. We must set this parameter if you choose to add more portal context information to the URL. Only versions '1.0’ and '2.0' are supported. Any other version creates an InvalidURLException exception.

/action

This is a required parameter if you call the action method of the portlet. The action parameter causes the action process of the portlet to be called. After the action has been completed, a redirect is automatically issued to call the render process.

To control the subsequent render process, a document servlet filter can set a request attribute with name 'com.ibm.websphere.portlet.action' and value 'redirect' to specify that the portlet serving servlet directly returns after action without calling the render process.

/mode=view | edit | help | custom-mode

This optional parameter defines the portlet mode used to render the portlet. The default mode is ‘view’. The value is not case-sensitive. For example, ‘View’, ‘view’ or ‘VIEW’ results in the same mode.

/state=normal | maximized | minimized | custom-state

This optional parameter defines the window state used to render the portlet. The default state is ‘normal’. The value is not case-sensitive, for example, ‘Normal’, ‘normal’, or ‘NORMAL’ results in the same state.

* [ /rparam=name *[=value] ]

This optional parameter specifies render parameters for the portlet. Repeat this parameter chain to provide more than one render parameter. For example, /rparam=invitation/rparam=days=Monday=Tuesday.

?name=value&name2=value2 …

Query parameters may follow optionally. They are not explicitly supported by the portlet container, but they do not invalidate the URL format.

/action | /resource

This parameter defines the methods of the portlet that is called. Valid values are no, action or resource parameter. No specific method defined calls the render method. The resource parameter is only supported for JSR 286 portlets.

/resource [/id=custom-id] [/cacheability=cacheLevelFull | cacheLevelPortlet | cacheLevelPage]

Set this parameter to define the method of the portlet to be called. No redirection occurs. No other method of the portlet is called.

To control the resource parameter, you can add an additional ID parameter to provide a resource serving identifier that is passed through to the portlet. The cacheability parameter defines the cache level of this resource URL. This parameter is only supported with JSR 286 portlets .

The following list includes examples of valid JSR 168 and JSR 286 URLs:


Portlet container
Portlet aggregation using JSP
Portlet preferences
Task overview: Managing portlets
Convert portlet fragments to an HTML document


Related


Portlet container settings

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