JSR-286 and AJAX

Chapter 6 Portals and AJAX This chapter excerpt from JBoss Portal Server Development by Ramanujam Rao, is printed with permission from Packt Publishing, Copyright 2007. NEXT>>

JSR-286 and AJAX

Among the set of features that the new portlet specifi cation JSR-286 introduces to make things easier for AJAX implementations, are the options to directly communicate with the portlet through shared render parameters and resource serving.

Referring back to the workaround option in JSR-168, the new specifi cation provides a standard for setting and receiving render parameters, and we no longer have to deal with manual copying OF context and parameters.

To set the render parameter directly to the response, all we have to do is this:

public class AssetPortlet extends GenericPortlet {
      public void processAction(ActionRequest request,
            ActionResponse response) {
          response.setRenderParameter("rate", "4.5");
     }
   ...
}

To receive render parameters in the portlet directly from the view, we can say:

public class AssetPortlet extends GenericPortlet {
     public void render(RenderRequest request, RenderResponse  response)
     {
             String rate = request.getParameter("rate");
             ...
     }
     ...
}

Similarly, the resource servicing option allows us to directly invoke the portlet from the portlet user interface, as follows:

ResourceURL resourceURL = renderResponse.createResourceURL()
<formaction="<%= resourceURL %> method="POST">
...
</form>

Using ResourceURL invokes a new life cycle method called serveResource()on the server, as follows:

public void serveResource(ResourceRequest req, ResourceResponse resp)
throws PortletException, IOException
{
resp.setContentType("text/html");
PrintWriter writer = resp.getWriter();
writer.print("<p><b>Response Markup</b>");
writer.close();
}

So, now when we use ResourceURL instead of ActionURL, the implementation of the asynchronous requests appears as follows:

Hence, we can conclude that the following approaches are available for implementing a portlet user interface:

• For a traditional, JSR-168 based implementation, ActionURL and RenderURL are still options, although very limited ones, for asynchronous call implementations
• For an AJAX implementation and asynchronous request-response, the ResourceURL option offered by JSR-286, is the best.

JBoss 2.7.0 offers full support for the JSR-286 Portlet 2.0 specifi cation, allowing us to implement robust AJAX-based applications without any workarounds.

With this background, let's dive right into developing a portlet for our "MyCompany" portal page using AJAX support. In subsequent sections, we will discuss the confi guration and other in-built AJAX support provided by the JBoss portal server.

NEXT>>

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