Therory - 60 :- Clent server Model, Peer - To Peer Network And Server Based Network

Client and Server model

• A client and server networking model is a model in which computers such as servers provide the network services to the other computers such as clients to perform a user based tasks. This model is known as client-server networking model.
• The application programs using the client-server model should follow the given below strategies:
• An application program is known as a client program, running on the local machine that requests for a service from an application program known as a server program, running on the remote machine.
• A client program runs only when it requests for a service from the server while the server program runs all time as it does not know when its service is required.
• A server provides a service for many clients not just for a single client. Therefore, we can say that client-server follows the many-to-one relationship. Many clients can use the service of one server.
• Services are required frequently, and many users have a specific client-server application program. For example, the client-server application program allows the user to access the files, send e-mail, and so on. If the services are more customized, then we should have one generic application program that allows the user to access the services available on the remote computer.

Client

A client is a program that runs on the local machine requesting service from the server. A client program is a finite program means that the service started by the user and terminates when the service is completed.

Server

A server is a program that runs on the remote machine providing services to the clients. When the client requests for a service, then the server opens the door for the incoming requests, but it never initiates the service.

A server program is an infinite program means that when it starts, it runs infinitely unless the problem arises. The server waits for the incoming requests from the clients. When the request arrives at the server, then it responds to the request.

Advantages of Client-server networks:

• Centralized: Centralized back-up is possible in client-server networks, i.e., all the data is stored in a server.
• Security: These networks are more secure as all the shared resources are centrally administered.
• Performance: The use of the dedicated server increases the speed of sharing resources. This increases the performance of the overall system.
• Scalability: We can increase the number of clients and servers separately, i.e., the new element can be added, or we can add a new node in a network at any time.

Disadvantages of Client-Server network:

• Traffic Congestion is a big problem in Client/Server networks. When a large number of clients send requests to the same server may cause the problem of Traffic congestion.
• It does not have a robustness of a network, i.e., when the server is down, then the client requests cannot be met.
• A client/server network is very decisive. Sometimes, regular computer hardware does not serve a certain number of clients. In such situations, specific hardware is required at the server side to complete the work.
• Sometimes the resources exist in the server but may not exist in the client. For example, If the application is web, then we cannot take the print out directly on printers without taking out the print view window on the web.

 

Peer-to-Peer

In a Peer-to-Peer network you take the machine currently in existence, install networking cards in them, and connect them through some type of cabling. Each machine is known as Peer and can participate in the sharing of files or resources. No server is required, so there is no additional cost for a dedicated machine, but there is also no real security.

Peer-to-Peer networks require an operating system that can understand networking and function in this (Peer-to-Peer) way. Microsoft Windows 95, Microsoft Windows 98, Windows NT server and Windows NT workstation can all function in Peer to-Peer environment.

If file and print sharing has been enabled on a Windows 95 system, for example, you can create a share by selecting a folder and choosing to share it. By default, no password is associated with it but you can choose to assign one that a user must know in order to access the resource. Access permission can be Read-Only, Full or depend on password this is known as share level security. Access is gained when a user supplies the correct password to access the share.-

Peer-to-Peer networking works in small environments. If you grow beyond approximately 10 machines, the administrative overhead of establishing shares, coupled with the lack of tight security, creates a nightmare.

Advantages of peer-to-peer network

• Server is not required
• No additional cost for dedicated-machine

Disadvantages of peer-to peer network

• Provides share level security
• Can work in small environments only
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Server Based

In the presence of server, be it on NetWare Or NT, you can implement user Network Fundamentals / 14 level security on your network. With the user level security, permissions are based on how the user logged on and was authenticated by the server. Every user has an account. In this environment, you can assign permissions to share based on user permissions or group permissions. In short you must have server on the network in order to have user level security, but you can have share level security with or without server.

This scenario also known as client/server networks (explain previously in chapter 1), server-based networking's down side is that it requires a dedicated machine (the server); the upside is that you gain centralize administration, you can add ail users at one location, control logon scripts and backups; and so on. With centralized authentication, you can identify a user to your entire network based on his logon name and password, not based on each share he attempts to access.

Advantages of Server based network

• Provides user level security
• You always gain centralize administration
• Can work in big environments also

Disadvantages of server based network

• Dedicated machine is required
• Cost of the system is more compared to peer-to peer networks.

-. Peer-to-Peer networks can exists comfortably within server-based networks. In many business combinations of two models are used. A server-based network is used to provide e-mail; and other resources to all users, and Peer-to-Peer networks are established within divisions to share resource among select users.

Microsoft, also calls Pee-to-Peer networks workgroup and server- based networks domains. These terms are used interchangeably in almost air Microsoft documentation.