Distributed Operating Systems

In a distributed operating system the functions of a conventional operating system are distributed throughout the network. A DOS is implemented as a collection of kernels and servers. Kernels and Servers are resource managers therefor they must provide

Encapsulation

The interface to the service must be usable by the clients. Details such as memory management should be hidden (even from local) clients.

Concurrent Processing

Clients must be able to share resources and use them concurrently

Protection

Resources must be protected from illegitimate access.

Clients access services by identifying them as arguments in calls of operations. This implies that a DOS must provide for

Name resolution

The server or kernel that manages the resource must be located from the identifier given to the resource

Communication

Parameter and resource names must be passed between resource managers on the network

Scheduling

The processing of requests has to be scheduled by the kernel or server.

Our discussion of DOS will consider the following

1. Kernels
2. Processes and Threads
3. Naming and Protection
4. Communication and Invocation
5. Virtual memory

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Last Changed: 14 October 1995