A CANCELLATION MECHANISM FOR COOPERATIVE SYSTEMS

摘要

An agent, service or process may request an operation by invoking an object that is implemented by another agent, service or process. Object invocation may be carried out by one thread in a service which may include multiple executing threads. After initiating the operation, the requesting agent may detect one or more conditions that make it advisable to cancel the requested operation. In a mechanism for implementing a cancellation operation in a cooperative system, a thread identifies an operation to be cancelled. A cancel function has an argument comprising the thread identifier in which the operation is to be cancelled. The cancel function is called by a client process thread to cancel a pending object invocation initiated by the client process. An immediate or hard cancel causes the targeted client and cancel thread to return immediately. A discretionary or soft cancel does not affect the targeted client thread. In either case the server process is notified via a maintenance notification. The target thread of the cancel cannot be reused for other work until the cancel request or notification has returned.