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Inter-Process Communication (IPC)

A capability supported by operating system that allows one process to communicate with other processes is called Inter-Process Communication. The processes can be running on same computer or on different computers connected through a network. IPC enables one application to regulate another application, and for several applications to share the same data without interfering with each other. IPC is required in all multi programming systems, but it's not generally supported by single-process operating systems like DOS.

Inter-Process Communication is a mechanism that is used by the processes to execute data and information. many processes may be executing at the same time in operating system.

There are two types of processes:

• Independent processes
• Cooperating processes

Independent Processes:

A process that can not affect or be affected by any other process executing in the operating system is called independent process. An independent process doesn't share data with any other process.


Cooperating processes:

Scheduler:

A process is passed in different Scheduling queues throughout its lifetime. The operating system select the processes from these queues in a way for scheduling purpose. The part of the operating system related to this selection is called the scheduler.

Scheduler

Scheduling Algorithm:

Scheduling algorithm is an algorithm which is to schedule the processes.

Three type of scheduling perform by the operating system:

• Long Term Scheduler
• Short Term Scheduler
• Medium Term Scheduler

Long Term Scheduler:

Long Term Scheduler or job scheduler is used to select a job or user program from job queue to the ready queue in the main memory. The job becomes a process after it has been added to the ready memory. The long term scheduler controls the number of processes in memory also known as the degree of multi programming. The system may get slow if too many processes are loaded into the main memory.


Short Term Scheduler:

The short term scheduler takes a process from ready queue and allocates CPU to that process for execution. It  is also called CPU Scheduler. The short term scheduler is invoked  vert frequently and must very fast. A Process is typically allocated the CPU for a very short period of time. It is move backed to ready queue after the given time is over. It may be executed only for a milliseconds. The short term scheduler then points the next process to execute from the ready queue. Thus the short term scheduling decisions much more frequently than the long-term and mid-term schedulers,


Medium Term Scheduler:

The medium-term scheduler removes the processes temporarily from main memory and places them on secondary memory such as a disk drive. It moves it back to main memory when required. It is commonly known as swapping in and swapping out. The medium -term scheduler may decide to swap out a process which has not been active for some time it has a low priority. It can also swap auto process that is taking up a large amount of memory to free up main memory for other [processes. It swaps in the process in later when more memory is available or when the process is unblocked and is not waiting fir a resource. It improves the performance of the system by reducing the degree if multi programming..

Process Scheduling:

Process scheduling is a strategy that is used when there are limited resources and many processes have to compete by using them. Multi programming tries to ensure that there is some process running at all times. This is due to utilize the CPU as much as possible. when system shares time, the CPU switches so frequently between jobs that the user not feel that the machine is being shared by many processes or even many users.
If the system has more than one processor. then it is possible, then it is possible to execute more than one processor at the same time. In a single processor system, only one processor can be executed at the given time. If there are more than more processes than processors, then the operating system must schedule the processes. It means that some processes will be executed and will have to wait. There are many queues for deciding which process should be assigned the CPU.
Scheduling Queues:

There are three types of queues.

• Job Queue
• Ready Queue 
• Waiting Queue

Jobs are submitted to a job queue. Each entering process goes into job queue. The processes in job queue reside on secondary storage and wait the allocation of main memory.

Satellite Communication:

Multiprocessors Systems:

Multiprocessing is a system in which two or more processors work together to process more than one program simultaneously. It allows the system to do more work in less time. UNIX is one of the most widely used multiprocessor systems.
Multiprocessor System is also referred to as parallel system or tightly- coupled system. It means that multiple processors are tied together in same manner. Generally, the processors are in a close communication with each other. They share same data structures and a same system clock.

Advantages of Multiprocessors Systems? 

Reduced Cost:

Multiple processor share same resources. Individual power supply or mother board for each chip of processor is not required. This reduces the cost.

Increased Reliability:

The reliability of system is also increased. In case of failure of one processor the other processors work efficiently though it will slow down the machine. Several machines are required to achieve increased reliability. When a processor failed, the process running on that processor also fails . The system must be able to reschedule the failed process or to alert the user that the process was not successfully completed. The system should be ready to schedule the unsuccessful job or to alert the user that the task was not completed successfully .


Increased Throughput:

An increased in the number of processors complete the work in less time. It is important to note that doubling the number of processors does not have the time to complete a job. It is due to the overhead in communication between processors and rivalry for shared resources etc.

Operating System (OS)

An operating system (OS) is a program intend to control the computer hardware and behave as an intermediary between user and hardware.




Linux Operating System:

Linux is a free operating system. It  is also open source operating system based on Unix standards user can make changes in it according to its needs. It provides programming interface compatible with Unix based system and provides large variety applications. A Linux system also contains several individually developed parts, resulting in Unix system which is fully compatible and free from proprietary code.


Windows Operating System:

Windows is a licensed operating system. Source code is inaccessible in it. It is designed for the individuals with the perspective of having no computer programming knowledge and for business and other commercial users. It is very simple and straightforward to use.

7 Differences between Linux and Windows Operating System

• Linux is open source operating system whereas Windows is a commercial operating system whose source code is inaccessible.

• The prior difference between Linux and Windows is that Linux is totally free of cost whereas windows is marketable operating system and is costly.

• Windows is not customize able as against Linux is customize and a user can modify the code and can change its look and feel.

• Linux provide high security than windows because Linux is open source.

• In Linux, file names are case sensitive whereas names of file are case insensitive in windows.

• The separation of directors is done using a backslash in windows. on the other hand, in Linux, these are separated by using forward slash.

• Linux uses the monolithic kernel which users more running space whereas Windows uses less running space but system running efficiency is slow than Linux.

What is Android?

Android is a mobile operating system. It is developed by Google. It is being used in many smart phones and tablets. For example it is used on the range of smartphones and tablets including those manufactured by Sony, Google, Xperia, Samsung, Huawei, Xiaomi, Acer, Motorola, LG and HPC .

The Android operating system (OS) is based on the Linux Kernel. Unlike Apple's iOS, Android is open source operating system. It means developers can modify and customize the OS for any phone. Different Android-based phones have different graphical user interfaces GUIs. They use the the same OS.

Android phones typically have many built-in applications and also support third party program. Developer can create programs by using the free Android developer kit (SDK). Android programs are written in Java.

Plus, Google further developments are Android TV for television, Android Auto for cars, Wear OS for wrist watches. Variety of Android are also used on game consoles, digital cameras, PCs and other electronics.