Section 14.1. A Note on Evolving Standards

14.1. A Note on Evolving Standards

At the time CORBA support was first made part of the core Java API, the CORBA specification and the IDL-to-Java binding for CORBA were in a bit of flux. The server-side object adaptor interface (the interface between remote object implementations and the core CORBA object services) had been altered significantly by the OMG in Version 2.3 of the CORBA specification. The Basic Object Adaptor (BOA) interface had been replaced by the Portable Object Adaptor (POA), which, as the name suggests, provides a portable implementation interface for CORBA server-side objects. This filled a gap in the specification left by the BOA that led to vendor-specific extensions and, therefore, CORBA server objects that were dependent on particular vendor Object Request Broker (ORB) implementations. The standard IDL-to-Java mapping, however, took some time to be updated to support the new POA, and JDK 1.2 was released before the new version of the Java mapping. As a stopgap measure, the first version of Java IDL in JDK 1.2 used a server-side object adaptor interface based on an ImplBase scheme. By the time JDK 1.4 was introduced in beta in 2001, the POA-compatible version of the IDL-to-Java mapping had been released, and the Java IDL packages, as well as the IDL-to-Java compiler in JDK 1.4, were based on this mapping. The Java 5.0 environment updated its Java IDL support only incrementally. Both JDK 1.4 and Java 5.0 support the CORBA 2.3.1 specification.

Another relatively recent addition to the CORBA specifications is the Interoperable Naming Service (INS) interface, which adds additional utilities and functionality on top of the standard CORBA Naming Service. INS was incorporated into the CORBA 2.3 specification, and support for it in Java IDL was introduced in JDK 1.4.

In this chapter, we discuss only the POA version of Java IDL. If you are using JDK 1.4 or later, you are using a POA-compatible mapping of the CORBA interfaces. If you are using JDK 1.3 or JDK 1.2, you are using the "pre-POA" version of the IDL-to-Java mapping that Sun used prior to adding the POA support. Most of the examples in the chapter would need to be revised somewhat to work in a pre-POA environment. We also limit our discussion to the more recent INS interface rather than the original Naming Service. Again, if you are using JDK 1.4 or later, you have access to the INS interface and the Naming Service provided with the Java IDL. The ORB supports these extended features. If you are using a prior version of the JDK, you have to use the original Naming Service interface, and the examples here will need to be revised to work in your environment.