Monitors, Semaphores and Rendezvous

The problem of providing ordered access to resources shared between processes has been solved traditionally by these three mechanisms. The Monitor is still a useful paradigm for building objects in a distributed system. The rendezvous provides a mechanism for communication as well as synchronisation. Semaphores are too low level and inappropriate for distribution in that to distribute the semaphore mechanism requires provision of distributed mutual exclusion to the semaphore operations. However, they are widely used for controlling concurreny within an object or process inside a distributed system.