11.1 Introduction

For either an Oracle Tuxedo CORBA client or joint client/server (that is, a client that can receive and process object invocations), the programmer writes the client main(). The main() uses Oracle Tuxedo CORBA environmental objects to establish connections, set up security, and start transactions.

Oracle Tuxedo clients invoke operations on objects. In the case of DII, client code creates the DII Request object and then invokes one of two operations on the DII Request. In the case of static invocation, client code performs the invocation by performing what looks like an ordinary invocation (which ends up calling code in the generated client stub). Additionally, the client programmer uses ORB interfaces defined by OMG, and Oracle Tuxedo CORBA environmental objects that are supplied with the Oracle Tuxedo software, to perform functions unique to Oracle Tuxedo.

For Oracle Tuxedo joint client/server applications, the client code must be structured so that it can act as a server for callback Oracle Tuxedo objects. Such clients do not use the TP Framework and are not subject to Oracle Tuxedo system administration. Besides the programming implications, this means that CORBA joint client/servers do not have the same scalability and reliability as Oracle Tuxedo CORBA servers, nor do they have the state management and transaction behavior available in the TP Framework. If a user wants to have those characteristics, the application must be structured in such a way that the object implementations are in an Oracle Tuxedo CORBA server, rather than in a client.

The following sections describe the mechanisms you use to add callback support to an Oracle Tuxedo client. In some cases, the mechanisms are contrasted with the Oracle Tuxedo server mechanisms that use the TP Framework.

Parent topic: Joint Client/Servers