Asynchronous Calls and Futures
Whenever possible, a method call on an active object is reified as an asynchronous request. If not possible, the call is synchronous, and blocks until the reply is received. If the request is asynchronous, it immediately returns a future object.
The future object acts as a placeholder for the result of the not-yet-performed method invocation. As a consequence, the calling thread can go on with executing its code, as long as it doesn't need to invoke methods on the returned object. If the need arises, the calling thread is automatically blocked if the result of the method invocation is not yet available. Although a future object has structure similar to that of an active object, a future object is not active. It only has a Stub and a Proxy.
Read more about this topic: Pro Active
Famous quotes containing the words calls and/or futures:
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—For the State of Vermont, U.S. public relief program (1935-1943)
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—Gertrude Stein (1874–1946)