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.
- JSF Extensions processes requests from HTML clients, calls application
logic layer components for business transactions, and renders presentation
for HTML clients based on the business transaction results.
- 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.