The underlying resources in a distributed system should be protected from illegitimate access. OS is responsible to dispatch interrupts, system call traps, memory management control, hardware cache and so on. OS also deals with management of physical and virtual memory to ensure efficient data sharing. In some OS, additional service is necessary for communication. OS is responsible for communication between threads attached to different processes on same computer or in remote processes. As a thread manager, OS is responsible for thread creation, synchronization and scheduling. As a process manager, OS handles the creation of processes and the operations upon them. Clients access resources by making invocations to a server object or system calls to a kernel. Kernal, as a resource manager, must provide encapsulation, protection and concurrent processing. ![]() ![]() Kernel and server processes are responsible to manage resources and present clients with an interface to the resources. Middleware is responsible to provide proper utilization of local resources to implement mechanisms for remote invocations between objects or processes at the nodes. The middleware-OS combination of a distributed system should have good performance. OS provides problem-oriented abstractions of the underlying physical resources. ![]() The OS layer is present below the middleware layer.
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