This thesis examines a programming construct of Symbian OS called active objects. Active objects encapsulate a request to an asynchronous service and the completion of that request. They can be used to implement cooperative multitasking inside one thread. Active objects are widely used throughout Symbian OS, and the Symbian documentation encourages their usage instead of multithreading.

In this thesis active objects are compared to threads by implementing a solution to classic producer/consumer problem using both programming methods. The performance of the solutions is then compared. The test results show that the active-object based solution performs the operation more quickly and uses significantly less memory than the thread-based solution.

Key words and phrases: Symbian, active objects, cooperative multitasking, asynchronous processing