This architecture is basically a client that makes requests to another program, the server – it responds. In this architecture the capacity is shared between the clients and servers , but more important are the benefits to organization due to the centralization of the management of information and separation of responsibilities, which facilitates and clarifies the design of system.

The separation between client and server is a separate logical type, where the server does not necessarily run on a single machine and is not necessarily a single program. Specific types of servers include cloud web servers, file , mail servers, etc. While their purposes vary from service to others, the basic architecture remains the same.

A common arrangement is the multilayer system in which the server is broken down into different programs that can be executed by different computers thereby increasing the degree of distribution ofsystem.

Server Features

In the systems C / S the recipient of the request sent by client is known as a server. Its features are:

• At the beginning wait for requests from clients, then play a role passive in the communication device ( slave ).

• Upon receipt of an application, process it and then send the customer response.

• Usually accept connections from a large number of customers (in some cases the maximum number of requests may be limited).

• It is not often that it interact directly with end users.

• Comparison of architecture C / S with other network architectures

• Comparison with networks of peers

The peer networks, also known as network peer-to-peer or peer-to-peer (abbreviated with the acronym P2P ) are another type of architecture network , because every node or element of the system can act at the same time as a client and a server, each node has, therefore, responsibilities and status of both.

Multi-layer architecture

The client / server architecture has two types of generic nodes in the network: clients and servers. Consequently, these generic architectures are sometimes referred to two-tier architectures or two layers .

Some networks have three types of nodes:

• Customers who interact with end users.

• Application servers that process data for customers.

• Servers that store database data for the application servers.

• This configuration is called a three-tier architecture.

Advantages of n-tier architecture:

The key advantage of an architecture n-layers compared to a two-tier architecture (or a three-tier to a two-tier) is that it separates out the process that happens to improve balance and the load on different servers, that is more scalable.

Disadvantages of n-tier architecture:

Puts more load on the network , because of Most of the network traffic.

It is much more difficult to program and test the software in architecture of two levels because more devices have to communicate to complete a transaction user.

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