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Handling Portlet requests

Shemida Nivedha

Joined: May 22, 2008
Posts: 18
I am new to portlets.
On comparing the portlets to servlets I have a doubt.
We know that the servlet container will spawn new threads & creates instances of portlets making it accessible for the requests received.
So how are the portlets handled?
Who takes care of the responsibility to spawn threads & make the portlets instance accessible?
Cameron Wallace McKenzie
author and cow tipper
Saloon Keeper

Joined: Aug 26, 2006
Posts: 4968

Portlets are in many ways similar to Servlets. In fact, in the old days, Portlet extended Servlet.

A big mistake of many new Portlet programmers is to use a Portlet as though it was a Servlet. Portlet programming IS different. But much of the semantics is the same. The portal server does run on a servlet engine, and the same type of threading that happens with Servlets happens with Portlets.

Portlets do have a slightly different lifecycle and lifecycle methods, but quite often, the way they are implemented behind the scenes are very, very similar.

-Cameron McKenzie
Jonas X. Yuan
Ranch Hand

Joined: May 18, 2008
Posts: 108

Abstract from JSR-286 spec.

Relationship with Servlets

A servlet is a Java technology based web component, managed by a container, which generates dynamic content [JSR 154]. Like other Java-based components, servlets are platform independent Java classes that are compiled to platform neutral byte code that can be loaded dynamically into and run by a Java enabled web server. Containers, sometimes called servlet engines, are web server extensions that provide servlet functionality. Servlets interact with web clients via a request/response paradigm implemented by the servlet container.

Portlets share many similarities with servlets:
�Portlets are Java technology based web components
�Portlets are managed by a specialized container
�Portlets generate dynamic content
�Portlets lifecycle is managed by a container
�Portlets interact with web client via a request/response paradigm

Portlets differ in the following aspects from servlets:
�Portlets only generate markup fragments, not complete documents. The Portal aggregates portlet markup fragments into a complete portal page
�Portlets can only be invoked through URLs
�Web clients interact with portlets through a portal system
�Portlets have a more refined request handling, action requests, event request, resource requests and render requests
�Portlets have predefined portlet modes and window states that indicate the function the portlet is performing and the amount of real state in the portal page
�Portlets can exist many times in a portal page

Books: Liferay Portal 6.1 Systems Development
Shemida Nivedha

Joined: May 22, 2008
Posts: 18
Hi all,
Thanks for the wonderful explanations.
Now I am clear with the differences.

I agree. Here's the link:
subject: Handling Portlet requests
jQuery in Action, 3rd edition