70 DCE Replacement Strategies
The developer must rewrite the DCE applications to run in the new
3.2.1 Determining a new architecture
The architect must determine a new J2EE component architecture to which each
DCE application will be rewritten. The following presents two examples of J2EE
component architectures. For complete information about J2EE component
architectures, refer to the J2EE and IBM WebSphere Application Server
Example 1: Java client applications and enterprise beans
This example maps to a DCE application consisting of application clients,
application servers, and back-end application servers, with all communications
being performed using the DCE RPC protocol.
In this example, the DCE RPC clients are rewritten to be Java client applications,
the DCE RPC servers are rewritten to be enterprise beans, and the back-end
DCE RPC servers are rewritten to be back-end enterprise beans.
Figure 3-1 illustrates this example:
Figure 3-1 Java client and back-end enterprise beans
The Java client application or the client enterprise bean finds the desired method
using the Java Naming and Directory Interface (JNDI) and invokes the desired
method using Java Remote Method Invocation (RMI). If the enterprise bean
containing the desired method is located on a remote node, the client serializes,
marshals, and transmits the method invocation using CORBA IIOP and, if
necessary, secures the IIOP transmission using CORBA CSIv2.
The administrator can configure CSIv2 so that client identity information is
passed to the target enterprise bean using client basic authentication (client
passes its user identity and password), client certificate authentication (client
passes its public certificate using an SSL transport), delegation, or identity
assertion. If CSIv2 is configured to use an SSL transport, SSL passes the public
certificate of the target enterprise bean to the client and protects the privacy and
integrity of all transmitted data.