TORBA: Trading Contracts for CORBA

Trading is a key function in the context of distributed applications: It allows runtime discovering of available resources. In order to standardize this function, the Open Distributed Processing (ODP) and Object Management Group (OMG) have specified a trading service for CORBA objects: The CosTrading. This specification has two main drawbacks: First, this service is complex to use from applications and second, it does not offer type checking of trading requests at compilation time. Both are discussed in this paper. The main goal of our Trader Oriented Request Broker Architecture (TORBA) is to provide a trading framework and its associated tools, which tend to offer typed trading operations that are simple to use from applications and checked at compilation time. In that, we define the concept of Trading Contracts, written with the TORBA Definition Language (TDL). Such contracts are then compiled to generate trading proxies offering simple-to-use interfaces. These interfaces completely hide the complexity of the ODP/OMG CosTrading APIs. In the meantime, TDL contracts could be dynamically used through a generic graphical console exploiting a contract repository. The example used in this paper, clearly states the advantages brought by the TDL trading contracts: type checking at compilation time, simple to use, and providing a powerful framework for CORBA object trading.