The application presentation layer works in conjunction with a
system application server (such as IBM® WebSphere® Application Server) to provide
a layered multiple channel architecture. The application presentation
layer works as a bridge that connects the clients with the application
logic layer, which performs business transactions. Java™ clients
and HTML clients use different application presentation components
to connect to the application logic layer.
To get connected with the application logic layer, the presentation
layer defines the following entities:
- Java RequestHandler processes
a Java client (Swing based or SWT based) request
for a particular type of requester. The toolkit registers these handlers
to determine which specific handler it needs for a specific request.
For example, there are different RequestHandlers for requests coming
from a Java client in a home banking environment, from
a Java client in a branch teller environment,
and from a Java client in a call center environment.
The RequestHandler is responsible for interacting with the client
side operations that controls the dialog navigation for a specific
client type and for interacting with invokers that call application
logic layer transactions.
- Java PresentationHandler processes
the reply for a particular type of requester (for example, DOJO).
- Web2.0 RequestHandler is responsible for processing a particular
request from Web 2.0 client. The request handler performs the following
tasks to integrate with the application:
- Executes a generic application operation for the Web 2.0 channel.
- Determines the appropriate presentation handler from the handler
registry to render the results back to the client.
- Web2.0 PresentationHandler is responsible for processing
the reply to the Web 2.0 client.
- HTML RequestHandler is responsible for processing
a particular request from an HTML client (The HTML client represents
the traditional Web1.0 application here). The handler may need to
be aware of the device type. This is managed by the channel context.
The request handler performs the following tasks to integrate with
the application:
- Establishes the session between the client and the server for
the specific device
- Executes a generic application operation for the HTML channel
- Determines the appropriate presentation handler from the handler
registry to render the results back to the client.
- HTML PresentationHandler is responsible for processing
the reply to the HTML client. The main API provided by this class
is void processReply(ChannelContext, ServerOperation).
This starts the process of dynamically creating the HTML and rendering
it to the client using the servlet JSP engine.
To pass business process requests to the application logic layer,
the application presentation layer has the Invoker Component. The
BTT Invoker Component creates invokers according to the different
protocol so that the requester can invoke the EJBs, WebServices, POJO
or JMS that perform the business processes in the application logic
layer.