This section describes the portal lifecycle from the application server start to its stop and how requests are handled.

Application Server start and stop

A portal instance is simply a web application deployed as a WAR in an application server. Portlets are also part of an enhanced WAR called a portlet application.

GateIn 3.5 does not require any particular setup for your portlet in most common scenarios and the web.xml file can remain without any GateIn 3.5 specific configuration.

During deployment, GateIn 3.5 will automatically and transparently inject a servlet into the portlet application to be able to interact with it. This feature is dependent on the underlying servlet container but will work out of the box on the proposed bundles.

Advanced WCI Registration

eXo Platform integrates with the web container to perform tasks such as automatic detection and registration of web applications. This is used by the portal container to detect when portlets are deployed and is accomplished through the WCI (Web Container Integration) component.

Some applications, especially Spring based portlets, may have requirements that specific servlets be started before any portlets are initialized. Although portlets and servlet initialization order are meant to be independent of each other, eXo Platform does have a way to get around these limitations imposed by these specific third party applications.

As a workaround to this issue, two new, advanced features have been integrated into the WCI component;

Advanced features:

Command Servlet

The servlet is the main entry point for incoming requests, it also includes some init codes when the portal is launched. This servlet (org.gatein.wci.command.CommandServlet) is automatically added during deployment and mapped to /tomcatgateinservlet.

This is equivalent to adding the following to web.xml.

<servlet>

  <servlet-name>TomcatGateInServlet</servlet-name>

  <servlet-class>org.gatein.wci.command.CommandServlet</servlet-class>

  <load-on-startup>0</load-on-startup>

</servlet>

  

<servlet-mapping>

  <servlet-name>TomcatGateInServlet</servlet-name>

  <url-pattern>/tomcatgateinservlet</url-pattern>

</servlet-mapping>

It is possible to filter on the CommandServlet by filtering the URL pattern used by the Servlet mapping.

The example below would create a servlet filter that calculates the time of execution of a portlet request.

The filter class:

package org.example;


import java.io.IOException;


import javax.servlet.FilterChain;

import javax.servlet.FilterConfig;

import javax.servlet.ServletException;

import javax.servlet.ServletRequest;

import javax.servlet.ServletResponse;


public class MyFilter implements javax.servlet.Filter {


  public void doFilter(ServletRequest request, ServletResponse response,

      FilterChain chain) throws IOException, ServletException

  {

    long beforeTime = System.currentTimeMillis();

    chain.doFilter(request, response);

    long afterTime = System.currentTimeMillis();

    System.out.println("Time to execute the portlet request (in ms): " + (afterTime - beforeTime));

  }


  public void init(FilterConfig config) throws ServletException

  {

  }


  public void destroy()

  {

  }


}

The Java EE web application configuration file (web.xml) of the portlet on which we want to know the time to serve a portlet request. As mentioned above, GateIn 3.5 does not require anything special to be included, only the URL pattern to set has to be known.

<?xml version="1.0"?>

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

    xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"

    version="2.5">

        

  <filter>

    <filter-name>MyFilter</filter-name>

    <filter-class>org.example.MyFilter</filter-class>        

  </filter>



  <filter-mapping>

    <filter-name>MyFilter</filter-name>

    <url-pattern>/tomcatgateinservlet</url-pattern>

    <dispatcher>INCLUDE</dispatcher>  

  </filter-mapping>    

    

</web-app>

See also