Windows 2000 is the first version of COM to support asynchronous method calls, which permit clients to make nonblocking calls to COM objects and objects to process incoming calls without blocking the calling threads. COM clients benefit from asynchronous method calls because they can continue working while waiting for outbound calls to return. Objects benefit because they can queue incoming calls and service them from a thread pool. Our SieveClient and SieveServer sample apps demonstrate how to create and use asynchronous clients and servers in COM-based distributed applications.
MSDN Magazine April 2000
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