A use case model shows a view of the system from the user perspective, thus describing what a system does without describing how the system does it. UML can be used to analyze the use case model, and to derive system objects and their interactions with each other and with the users of the system. Using UML techniques, you further analyze the objects and their interactions to derive object behavior, attributes, and relationships.

Definition: Systems design is the process of defining the architecture, modules, interfaces, and data for a system to satisfy specified requirements. Systems design could be seen as the application of systems theory to product development.

1.                  Traditional waterfall SDLC

2.                  Agile methodologies

3.                  Object oriented analysis and design (OOAD)

a.         Batch Processing:

Batch processing is a general term used for frequently used programs that are executed with minimum human interaction. Batch process jobs can run without any end-user interaction or can be scheduled to start up on their own as resources permit.

B.        Multiprocessing:

Multiprocessor Operating System refers to the use of two or more central processing units (CPU) within a single computer system. These multiple CPUs are in a close communication sharing the computer bus, memory and other peripheral devices. These systems are referred as tightly coupled systems.

These types of systems are used when very high speed is required to process a large volume of data. These systems are generally used in environment like satellite control, weather forecasting etc.

c.         Bootstrapping:

A bootstrap is the program that initializes the operating system (OS) during startup. The term bootstrap or bootstrapping originated in the early 1950s. It referred to a bootstrap load button that was used to initiate a hardwired bootstrap program, or smaller program that executed a larger program such as the OS. The term was said to be derived from the expression “pulling yourself up by your own bootstraps,” starting small and loading programs one at a time while each program is “laced” or connected to the next program to be executed in sequence.

d.        Real-Time Processing:

Real-time data processing is the execution of data in a short time period, providing near-instantaneous output. The processing is done as the data is inputted, so it needs a continuous stream of input data in order to provide a continuous output. Good examples of real-time data processing systems are bank ATMs, traffic control systems and modern computer systems such as the PC and mobile devices. In contrast, a batch data processing system collects data and then processes all the data in bulk in a later time, which also means output is received at a later time.

Real-time data processing is also known as stream processing.

e.        Time Sharing:

A time sharing operating system is that in which each task is given some time to execute and all tasks are given time so that all processes run seamlessly without any problem. Suppose there are many users attached to a single system then each user has given time of CPU. No user can feel to have trouble in using the system.

Round Robin Scheduling:

Round robin scheduling is an algorithm mainly used by operating systems and applications that serve multiple clients that request to use resources. It handles all requests in a circular first-in-first-out (FIFO) order and eschews priority so that all processes/applications may be able to use the same resources in the same amount of time and also have the same amount of waiting time each cycle; hence it is also considered as cyclic executive.

Distributed network:

A distributed network is a type of computer network that is spread over different networks. This provides a single data communication network, which can be managed jointly or separately by each network. Besides shared communication within the network, a distributed network often also distributes processing.

Virtual Memory:

Virtual memory is a memory management capability of an OS that uses hardware and software to allow a computer to compensate for physical memory shortages by temporarily transferring data from random access memory (RAM) to disk storage. Virtual address space is increased using active memory in RAM and inactive memory in hard disk drives (HDDs) to form contiguous addresses that hold both the application and its data.

The process scheduling is the activity of the process manager that handles the removal of the running process from the CPU and the selection of another process on the basis of a particular strategy.

Deadlock:

A deadlock is a situation in which two computer programs sharing the same resource are effectively preventing each other from accessing the resource, resulting in both programs ceasing to function.

Race Condition:

A race condition is an undesirable situation that occurs when a device or system attempts to perform two or more operations at the same time, but because of the nature of the device or system, the operations must be done in the proper sequence to be done correctly.

Processes may be in one of 5 states:

New - The process is in the stage of being created.

Ready - The process has all the resources available that it needs to run, but the CPU is not currently working on this process's instructions.

Running - The CPU is working on this process's instructions.

Waiting - The process cannot run at the moment, because it is waiting for some resource to become available or for some event to occur. For example the process may be waiting for keyboard input, disk access request, inter-process messages, a timer to go off, or a child process to finish.