| 摘要 |
An object-oriented framework is used to build cooperative objects. Objects can span processes on different machines connected by a network. The objects are used to build distributed or cooperative applications which execute in multiple environments without having to write significant additional code to enable such functionality. Each cooperative object has two parts: an agent object and a server object. Requests for services are made to agent objects by the application program (via an asynchronous interface) as if they were local objects. The server object performs the requested service in the server process, possibly using other server objects or systems (e.g., DB/2), and returns the result to the associated agent object. A Distributor and Dispatcher object in each process handle communication between agent and server objects. The Distributor receives all incoming messages and routes them to the appropriate objects in the process. The Dispatcher is used for sending messages to other objects. Agent and server objects use framework methods SendMessage and HandleMessage to send/receive messages to/from other objects. Message data is converted to account for parameter types in different processing environments (e.g., byte-swapping and ASCII to EBCDIC). Upon receipt of a message, the Distributor automatically calls the HandleMessage method of the receiving object. The object then processes the request according to the user-defined implementation of the HandleMessage method and, in the client process, notifies the application of the completion of a request via a Callback method.
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