Chapter 3 defines distribution services as services which allow to distribute applications over a system or over a network. Applications using these distribution services still have to put some syntax and semantics in the information they exchange, but they do not have to care any more about addresses and synchronisation. The present chapter provides a more detailed description of these services, by covering today’s best known models for distributed computing: the client/server model, the producer/consumer model, the model of the OSI upper layers. Two well-known distribution services are then presented: the Distributed Computing Environment (DCE) from the Open Software Foundation (OSF) and the Dynamic Data Exchange (DDE) from Microsoft. These provide distributed applications with the means to exchange data, wherever they are. With the increasing use of object technology, there is a need for higher level distribution services that allow objects to communicate with one another, independently of their location. As CCE heavily relies on object technology, there is a need of this kind for the CCE platform. Two important distribution services of the future are described: the Common Object Request Broker Architecture (CORBA) from the Object Management Group (OMG) and the Object Linking and Embedding (OLE) from Microsoft.
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