Active object

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The active object design pattern decouples method execution from method invocation for objects that each reside in their own thread of control.[1] The goal is to introduce concurrency, by using asynchronous method invocation and a scheduler for handling requests.[2]

The pattern consists of six elements:[3]

  • A proxy, which provides an interface towards clients with publicly accessible methods.
  • An interface which defines the method request on an active object.
  • A list of pending requests from clients.
  • A scheduler, which decides which request to execute next.
  • The implementation of the active object method.
  • A callback or variable for the client to receive the result.

See also[edit]


  1. ^ Douglas C. Schmidt; Michael Stal; Hans Rohnert; Frank Buschmann (2000). Pattern-Oriented Software Architecture, Volume 2: Patterns for Concurrent and Networked Objects. John Wiley & Sons. ISBN 0-471-60695-2. 
  2. ^ Bass, L., Clements, P., Kazman, R. Software Architecture in Practice. Addison Wesley, 2003
  3. ^ Lavender, R. Greg; Schmidt, Douglas C. "Active Object" (PDF). Retrieved 2007-02-02.