Abstract: There is provided an object orientated heterogeneous multi-processor architecture comprising a plurality of execution units amongst which object methods are distributed, a run-time support, a shared memory for storing object data and which is accessible by the execution units and by the run-time support, and an invocation network for carrying method invocation messages between execution units and/or between the run-time support. Object based source code is distributable across a variable number of the execution units. The invocation network is logically distinct from any mechanism for accessing the object data stored in the shared memory. Also provided are methods of operating the heterogeneous multi-processor architecture and of managing communications in an object orientated program execution environment.