Simply we can say that the Distribution System is a collection of independent computers connected by a computer network that appear to the user as a single computer. Today it helps to develop the information technology and modern technic of internet. This is more powerful than personal systems and the cost will be reduced. The machines which are in distributed system are not sharing memory, instead of that they share messages between them. The users who are connected with the Distributed System are enabled to share resources, hardware, software and other data. That is very useful for the persons in every position in organizations.

1. DISTRIBUTED SYSTEMS AND APPLICATIONS
ICT 1308 – Assignment#01 ICT 2010/2011 / 013
Operating Systems

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What is the Distributed system?
Simply we can say that the Distribution System is a collection of independent computers connected by a computer network that appear to the user as a single computer.
Today it helps to develop the information technology and modern technic of internet. This is more powerful than personal systems and the cost will be reduced. The machines which are in distributed system are not sharing memory, instead of that they share messages between them. The users who are connected with the Distributed System are enabled to share resources, hardware, software and other data. That is very useful for the persons in every position in organizations.
Features of Distributed System
1. Resource sharing – Can be shared software and hardware anywhere in the system.
2. Transparency – Distributed system should be understood by user than as a collection of cooperating components. There are few transparencies such as Scalability, Performance, Migration, Access etc.
3. Openness – It is free to use any components from different vendors.
4. Concurrency – Components access & update shared information which is executed in concurrent process.
5. Fault tolerance – When error has occurred, the system can be continued.
6. Scalability – The system can adapt for accommodating more users and fast response.

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7. System architecture
Multi-processor architecture
This is the simple model which contains multiple processors that execute on different processors. This is given more power to individual. Client / Server architecture Distributed services which are called on by clients. Servers that provide services are treated differently from clients that use services. There are few types in computing.
Distributed object architecture
There are no specification between clients and servers. Any object on the system may provide and use services from other objects.
Uses of Distributed System
 Grid computing
Grid computing is a form of distributed computing. This is used by organizations such as business, university, etc. and it uses existing computers to handle its own long-running computational tasks. Computers in grid may have different hardware and operating systems.
 Utility computing
A utility computing is one in which customers receive computing resources from a service provider and it makes computing resources and infrastructure management available to the customer as needed. There are advantages using that method that is low or no initial cost to capture computer resources.

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 Cloud computing
This is a style of Grid Computing and it is a type of computing that relies on sharing resources rather than having local servers or personal devices. This is a very famous service among users in internet. You can choose that you want a free service or a paid service with more facilities. The free service is using every now and then. This technology allows for more efficient computing by centralizing data storage, processing and bandwidth with servers. You can choose public cloud or personal cloud for your type.
Cloud computing provides a shared pool of resources, including data storage space, networks, computer processing power, and specialized corporate and user applications. There are many usages of cloud computing service.
 Email – This is the largest cloud computing service in the internet. There are many email providers like “Gmail, Hotmail, Yahoo mail and etc.”
 Cloud storage and backup service – This service can be used to store your data in a cloud space. This will be helping you to save your data safe and free your local memory space. There are free and paid service providers to maintain your data in cloud. E.g.: “Google, Box, mozy, SOS, zip cloud and etc.”
 Hosting – This service allows you to host your own data such as pictures, videos and any other documents in the cloud storage and it can be used to share your documents. Social networking sites are used this service widely. You know that daily people are sharing their documents through internet with help of cloud service. “YouTube, Flicker, Photobucket, FileFactory and etc.” are the examples for hosting services.
 Online software services – Today you need not to install all the software in your machine instead of that cloud service allows you to do everything in online. “Office365, thinkfree, pixlr and etc.”

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Advantages of Distributed System
1. Sharing data and resources – Sharing is the most useful advantage through Distributed system. Banking systems, reservation systems and other systems for computerized companies are using this technology widely.
2. Reliability – This system is connected as a network so if one machine crashed it is not effect to the system.
3. Speed – The collection of processors provide high speed and best performance.
4. Incremental growth – New machines can be added incrementally.
5. Communication – It helps to human to human communication.
6. Distribution – Many applications can be involved to the system.
Disadvantages of Distribution System
1. Networking problems – Some problems can be created through the network such as loosing data and messages, rerouting, rewiring network (is hard and cost is high) etc.
2. Security – Less security and issues confidentially and integrity.
3. Manageability – It is very hard to manage the system.
4. Software – Developing distributed system software is hard.
5. Complexity – Distribution system is very complex than single machine.