Sequential Systems

Question 1 (a) Strength: Sequential systems are relatively simple to design and build. Weakness: Due to the differing speeds of the hardware components, the slower components will become bottlenecks of sequential systems. (Another weakness is that the faster components may be under-utilized.) (b) Definition: A concurrent system can perform several tasks at the same time. The system may perform the tasks on a CPU interleaved to give an impression of several activities happening simultaneously. Strength: A concurrent system allows the faster components to be better utilized. (For example, a CPU can do productive work for another program while one program is waiting for a slow IO (input-output) activity to finish.) Weakness: Programming for concurrent systems are more challenging. (For example, deadlock may be possible.) (c) Definition: A distributed system is a special case of a concurrent system with a number of components located in distinct places. Strength: One of faulttolerant, resource sharing and scalability. Weakness: Programming for distributed system is potentially even more challenging than that for concurrent systems because of the remotely located components, slow and potentially unreliable communication. Question 2 (a) When an operating system launches a program for execution, it creates a process. Therefore a process is the dynamic counterpart of a static program. (b) A process consists of one or more threads. Threads are smaller units of execution inside processes. (c) Starvation means that a process continues to be denied the resource(s) it needs to progress. (d) A deadlock is a situation in which two or more processes are waiting for each other to release resources. None of the deadlocked processes can make any progress without the required resources. (e) Mutual exclusion means that only one process or thread can access a shared resource at a time. It is necessary for example to prevent the corruption of shared data. Question 5 (a) Session beans...