What is Distributed System
"In a Distributed system, multiple Autonomous independent computers are connected together and used as a single system. It is not necessary that all the computers are connected in one place. It can also be connected in different places if all the computers are in the same place. Connected in place, it will be called LAN Distributed System and if all the computers are connected in a different place then it will be called WAN Distributed System. "
Distributed System requires three things
- Network
- Distributed Application
- Middleware Service
The distributed system is made up of a collection of Autonomous computers. These systems are connected through a network and Distribution Middleware. Which enables computers to coordinate with their activities. And shares system resources. So that users get the system as a Single Integrating Computing Facility.
A distributed computer system consists of a number of software components. Which are on multiple computers, but run as a single system. Computers that are in a distributed system can be physically close to each other and are connected through a Local Network. Or they are connected through Wide Area Network. A distributed system may consist of several configurations in the form of mainframes, personal computers, workstations, etc. The goal of Distributed Computing is to create a network that acts like a single computer.
Distributed System is based on the Client-Server Architecture system -
Client-server architecture is a common way of running software on a distributed system is to separate the functions into two parts of the Clients and Servers. A client is a program that uses those services. Which are made available by other programs. Those who provide Programs service. They are called Servers. The client requests a request for a service and the server performs this request.
The general design of the Clients and Server System uses three tiers-
1. A client who interacts with the user.
2. An application server that holds the business logic of the application.
3. Resource manager that stores data.
Advantages and Disadvantages of Distributed System
Cost
Hardware used for Computers Component has a low cost depending on performance.
1. Performance
The performance layer is good by using the combined processing and storage capacity of many Nodes. That is, the collection of processes gives better performance than centralized computers.
2. Reliability
Users can change this at the hardware fault. That is, if some machine becomes Crash, System Survive can do it.
3. Distribution
Some applications such as E-Mail and the Web are distributed naturally.
4. Sharing of data/resources
It is necessary to prepare data in many applications. Such as backing reservation system etc.
Disadvantages of Distributed System
1. Software Complexity
Developing distributed software is complex and confusing as compared to traditional software, so it is more expensive to develop it. And there is a lot of Chance of gals in it.
2. Network Problems
Many problems arise due to network infrastructure, due to which there is the loss of message, overloading, etc.
3. Security
The Distribute System consists of several components. Sharing data between these components generates the problem of data security.
4. Design Issue of Distributed System -
Following are its major Design Issue, which is specifically generated from the Distributed Nature of the application.
1. Transparency
2. Communication
3. Performance and Scalability
4. Heterogeneity
5. Openness
6. Reliability and Fault Tolerance
7.Security
1. Transparency - Under this, the following points are considered
(a) Local and remote resources are accessed using Identical Operations.
(b) Users cannot tell where the hardware and software resources are located, these resources are CPU Files Database, etc. The name of the resource should not encode the location of the resource. (c) Resources should be independent of moving from one location to another without changing their name.
2. The components of the communication-distributed system should be communicated in order to interact. These indicate support on two occasions.
(a) Networking Infrastructure.
(b) Appropriate Communication Primitives and Modems and their Implementation.
3.Performance and Scalability Performance and Scalability - The following major thumb impressions affect a distributed system performance
(a) Performance of individual workstations.
(b) Speed of Communication Infrastructure.
4. Heterogeneity-distributed applications are generally heterogeneous at the following points
(a) Different hardware - Mainframe, Workstations, PCS, Servers, etc.
(b) Different software - Unix, MS Windows IBM OS / 2, Real-time OS, etc.
5. Openness- An important feature of distributed systems is Openness and Flexibility. The following points are considered under this
(a) Each service should be accessed equally by each client.
(b) It is easier to install and debug and implement new services.
6. Reliability and Fault Tolerance- The main advantage of creating a distributed system is to improve reliability.
Reliability- If the machines go bad then the system should work with the number of resources changed. Data should not be lost on the system and copies should be stored correctly on different servers.
7. Security- The following points fall under the security of information resources
(a) Restricting access to the unauthorized person.
(b) Protection against change and corruption.
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