web server - Borland Technical Publications

Application development overview
The Connectors 1.0 specification defines the CCI for EIS access. The CCI is a
standard client API for application components that enables these and EAI frameworks
to drive interactions across heterogeneous EISs. The CCI is primarily targeted for
Enterprise Application Integration (EAI), third-party enterprise tool vendors, and
migration of legacy modules to the J2EE Platform.
In the CCI, a connection factory is a public interface that enables connection to an EIS
instance. The ConnectionFactory interface is implemented by the Resource Adapter to
provide this service. An application looks up a ConnectionFactory instance in the JNDI
namespace, and uses it to request to obtain EIS connections.
The application then uses the returned Connection interface to access the EIS. To
provide a consistent application programming model across both CCI and EIS-specific
APIs, the ConnectionFactory and Connection interfaces comply to the Interface
Template design pattern. This defines the skeleton of the connection creation and
connection closing, deferring the appropriate steps to subclasses. This allows for these
interfaces to be easily extended and adapted to redefine certain steps of connection
creation and closing without changing these operations' structure. For more
information on the application of the Interface Template design pattern to these
interfaces, refer to Section 5.5.1 in the Connectors 1.0 specification (http://
java.sun.com/j2ee/connector).
Managed application scenario
The following steps are performed when a managed application requests to obtain a
connection to an EIS instance from a connection factory, as specified in the res-type
variable:
1 The application assembler or component provider specifies the connection factory
requirements for an application component by using a deployment descriptor:
res-ref-name: shme/shmeAdapter
res-type:javax.resource.cci.ConnectionFactory
res-auth: Application | Container
2 The Resource Adapter deployer sets the configuration information for the Resource
Adapter.
3 VisiConnect uses a configured Resource Adapter to create physical connections to
the underlying EIS.
4 The application component performs a JNDI lookup of a connection factory instance
in the component's environment:
// obtain the initial JNDI Naming context
javax.naming.Context ctx = new javax.naming.InitialContext();
// perform the JNDI lookup to obtain the connection factory
javax.resource.cci.ConnectionFactory cxFactory =
(javax.resource.cci.ConnectionFactory)ctx.lookup(
"java:comp/env/shme/shmeAdapterConnectionFactory");
5 The JNDI name passed in the context lookup is that same as that specified in the
res-ref-element of the component's deployment descriptor. The JNDI lookup returns
a connection factory instance of type java.resource.cci.ConnectionFactory as
specified in the res-type element.
6 The application component invokes the getConnection() method on the connection
factory to request to obtain an EIS connection. The returned connection instance
represents an application level handle to an underlying physical connection. An
application component requests multiple connections by invoking the
getConnection() method on the connection factory multiple times.
javax.resource.cci.Connection cx = cxFactory.getConnection();
7 The application component uses the returned connection to access the underlying
EIS. This is specific to the Resource Adapter.
Chapter 27: Using VisiConnect 271