Module Structure

The Forum application is partitioned into three modules: forum-services, forum-web, and forum-style. As you know from the introduction to modules, modules provide a means to aggregate, manage and version functions of an application.

For the Forum application, the forum-web module contains all of the code responsible for interactions with the user through a browser interface - the 'web-application'.

It exports the public address space ffcpl:/forum/.*, delegates styling and presentation to the forum-style module, and uses the capabilities of the forum-services module to perform the actual forum-related work, such as saving postings to the database.

Module	Description
forum-web	The web-application framework and public web-application interface.
forum-style	Pluggable styling and presentation.
forum-services	The core application services. These include data services accessing the Forum database as well as installation and management applications.

The high-level structure of the Forum application is illustrated in the following diagram.

   ffcpl:/forum/.*
         ^
         |
         V
     forum-web <---> forum-style
         ^
         |
         V
   forum-services
				

Fulcrum Module

To expose the forum web-application to an HTTP transport, the forum-web module must be imported into a fulcrum. As you know, a fulcrum is the name given to a module that hosts one or more transports. The following diagram depicts the import of the forum-web module into the front end fulcrum for access on the HTTP transport exposed on port 8080

       HTTP Transport :8080
               ^
               |
               V
        Frontend-Fulcrum
               ^
               |  http://.../forum/.*  ->  ffcpl:/forum/.*
               V
           forum-web
                    

Importing

The forum-web module is imported into the front end fulcrum in the <mapping> section of the front end fulcrum's module.xml file. Examine this file located in [install]/modules/mod-fulcrum-frontend/module.xml, and note the relevant import tag:

This import specification refers to the name of a module (declared in a module's module.xml file) and made known to NetKernel through inclusion in [install]/etc/deployedModules.xml.

Mapping

The front end fulcrum is constructed to map http:/ requests into the internal NetKernel ffcpl:/ address space. In the case of the forum application the following path mapping is significant

http://.../forum/.*  ->  ffcpl:/forum/.*

Since the forum-web module is imported into the front end fulcrum and the forum-web module declares that is exports ffcpl:/forum/.* in the export section of it's module.xml file, then all requests for the forum application are sent to the forum-web module.