ExecutionContext

Integrating JForum

JForum uses ThreadLocal for its execution contexts, which is where all the action occurs. In order to execute anything related to JForum, you have to setup the execution context, represented by the class net.jforum.JForumExecutionContext. The most commonly used methods are: get(), set(), setConnection() and setForumContext()

This last being an instance of'net.jforum.context.ForumContext, usuallynet.jforum.context.JForumContext.

A ''ForumContext'' contains the HTTP Request and Response, as well the ''context path' and JForum's servlet extension.

Creating a ''complete'' execution context

By ''complete'' we mean an execution context that has a request, response and JDBC connection. Not every time you will need all this information - it depends of what you are trying to do -, but it is very likely that at least the HTTP request will be necessary.

import net.jforum.JForumExecutionContext;
import net.jforum.context.ForumContext;
import net.jforum.context.JForumContext;
import net.jforum.context.web.WebRequestContext;
import net.jforum.context.web.WebResponseContext;

// .....

try {
    // Retrieve an existing or create a new execution context
    JForumExecutionContext executionContext = JForumExecutionContext.get();

    // Create a ForumContext
    ForumContext forumContext = new JForumContext(request.getContextPath(), 
        ".page", 
        new WebRequestContext(request), 
        new WebResponseContext(response));

    executionContext.setForumContext(forumContext);

    // If you have a valid JDBC connection at this point, you can set it as well
    executionContext.setConnection(connection);

    // Set back the new execution context, so we can use it
    JForumExecutionContext.set(executionContext);

    // ....
    // Execute all your JForum code here
    // ....
}
finally {
    // Release the resources
    JForumExecutionContext.finish();
}

In lines 16 and 17 we create new instance of WebRequestContext' and WebResponseContext, passing a valid instance of a HttpServletRequest and HttpServletResponse respectively. It is supposed you already have such instances (e.g, from your Servlet / JSP).

A note about the JDBC Connection

In line 23 we manually set a JDBC connection. If we don't do that, JForum will make a call to the method getConnection() of the class JForumExecutionContext, trying to get a connection from JForum's configuration.

However, the example code doesn't tell the whole history. By calling JForumExecutionContext.finish(), JForum will also try to release such connection, even if it was manually set. To prevent JForum of doing that - for example, if you have your own connection poll and / or want to use that connection besides JForum execution context, you have to set it to ''null'', as shown in the following code:

// ....
// By setting the connection to null, we prevent JForum of trying to release it when finish() is called
executionContext.setConnection(null);
JForumExecutionContext.set(executionContext);

// Now, when calling JForumExecutionContext.finish(), JForum will not try to release that connection
JForumExecutionContext.finish();

Recap

• Always use the execution context inside a try-finally block;
• Never forget to fall JForumExecutionContext.finish()
• Retrieve the execution context by calling JForumExecutionContext.get()
• A ''ForumContext'' holds the request and response
• The default implementation of ''ForumContext'' is ''JForumContext''
• You can manually set a JDBC connection using the method setConnection()'
• If not usingsetConnection(), JForum will try to retrieve one from its connection poll