In a distributed system, the following things happen:

• All hardware and software components are located remotely; they coordinate and communicate with each other by passing the messages.
• Resource sharing is the most important aspect of a distributed system; resources are managed by the servers and clients uses these resources.

A distributed operating system runs on a number of independent sites, those are connected through a communication network, but users feel it like a single virtual machine and runs its own operating system.

The figure below gives the architecture of a distributed system. It shows the workstations, terminals, different servers are connected to a communication network. It shares the services together. Each computer node has its own memory. Real life example of a distributed system is the Internet, Intranet, mobile computing, etc.

The characteristics of the distributed system are given below:

Concurrency: All the services should be active concurrently and shares resources. E.g. web pages, files, etc.

No global clock: Computers are connected through a network in the distributed system having own clock. Communication between the nodes is done through message passing and their coordination is depending on time. Every client or computer has a different time span. But accurate time synchronization is impossible in a distributed environment because it does not provide a global clock.

Independent Failure: Each component in a distributed system can fail independently without knowing others. Though a single component fails, others continue with their own task without getting disturbed.

Advantages of distributed system

1. The distributed system gives high performance than the single system. Because processing is combined and storage capacity is more. So it provides better services to the consumers.

2. It is more scalable as we can add the resources easily and increase the power of computing. Therefore sharing also becomes easy.

3. The important advantage of the distributed computing system is reliability. It is more reliable than a single system. If one machine from the system fails, the rest of the computers remain unaffected and the system can work as a whole.

Disadvantages of distributed system

1. If one or more network links fail or any server fails, then it is harmful to the other nodes which are connected and consuming the services from it.

2. It is easy to share the data in a distributed system. So, this can create a risk of security .

3. Distributed system supports the less software.

Applications of a distributed system

1. In Telecommunication networks:

The distributed system is useful in Phone networks and cellular networks. PC networks like the Internet, Wireless sensor networks, Routing algorithms are also the example of a distributed system.

2. Network applications:

Many network applications use the distributed system such as Web and p-2-p networks as well as multiplayer web-based games and virtual communities. Distributed database management systems and distributed databases also base of this system. Network files systems, distributed info processing systems like banking systems and airline reservation systems are another example of a distributed system.

3. Real-time process control:

The distributed system used in aircraft control systems and business control systems.

4. Parallel computation:

Systematic computing, including cluster computing and grid computing and varied volunteer computing projects are on the basis of a distributed system.