Configuration

Plexus Servlet module exists for simplifying embedding and usage of Plexus in context of web applications which run inside the servlet container.

There are two ways of embedding Plexus.

1. By setting up a PlexusServletContextListener
2. By setting up a PlexusLoaderServlet.

   The first way is suported by servlet containers which are compliant with servlet specification 2.3 or higher. Second one should be used for compatibility with older versions of servlet containers

Setting up PlexusServletContextListener to embed Plexus

<web-app>
  ...
  <listener>
    <listener-class>org.codehaus.plexus.servlet.PlexusServletContextListener</listener-class>
  </listener>
  ...
<web-app>

Setting up PlexusLoaderServlet to embed Plexus

<servlet>
  <servlet-name>plexus</servlet-name>
  <servlet-class>org.codehaus.plexus.servlet.PlexusLoaderServlet</servlet-class>
  <load-on-startup>1</load-on-startup>
</servlet>

By default, in both the above cases, the Plexus Embedder will search for the configuration files in the following locations:

• /WEB-INF/plexus.xml (for main Plexus configuration file)
• /WEB-INF/plexus.properties (for properties file which is used for seeding Plexus context)

  These location can be overidden TODO: explain how

In both the above cases a new instance of Plexus Conatiner will be created and stored in "application" scope for the web application under the key: org.codehaus.plexus.PlexusConstants.PLEXUS_KEY

How to lookup and release components

...
ServletContext context = getServletContext();
VelocityComponent velocityComponent = ( VelocityComponent ) PlexusServletUtils.lookup( context, VelocityComponent.ROLE );
...
PlexusServletUtils.release( context, velocityComponent );
...

<%
...
VelocityComponent velocityComponent = ( VelocityComponent ) PlexusServletUtils.lookup( application, VelocityComponent.ROLE );
...
PlexusServletUtils.release( application, velocityComponent );
...
%>

public abstract class BaseAction extends Action
{
    protected Object lookup( HttpServletRequest request, String role )
        throws ServletException
    {
        HttpSession session = request.getSession();

        ServletContext application = session.getServletContext();

        Object retValue = PlexusServletUtils.lookup( application, role );

        return retValue;
    }

    protected void release( HttpServletRequest request, Object component )
        throws ServletException
    {
        HttpSession session = request.getSession();

        ServletContext application = session.getServletContext();

        PlexusServletUtils.release( application, component );
    }

    void someAction( HttpServletRequest request )
    {
        VelocityComponent velocityComponent= ( VelocityComponent ) lookup( request,  VelocityComponent.ROLE  );

        ....

        release( request, velocityComponent );
    }
}

Obtaining the Plexus Container instance

If you need to access the instance of PlexusContainer object, it can be obtained by the following call:

PlexusContainer getPlexusContainer( ServletContext servletContext )

<dependency>
  <groupId>plexus</groupId>
  <artifactId>plexus-servlet</artifactId>
  <version>1.0-beta-2</version>
</dependency>