Client–server model
The client -server model (also client - server concept, architecture, system or principle called ) describes a way of tasks and services within a network to distribute. The tasks to be done by programs that are divided into clients and servers. The client may wish to request a service from the server (such as a resource ). The server is located on the same or any other computer in the network, responds to the request ( that is, it is in the example resource providing ).
Definitions
Client- server model
The client -server model is the standard approach to the distribution of tasks within a network. Tasks are distributed via servers on different computers and can be requested them if necessary from multiple clients to solve their own tasks or parts. For the tasks it can be standard tasks ( e -mails, e- mail reception, web access, etc.) or specific tasks of a software or a program. A task is called in the client -server model as a service.
A server is a program that provides a service (Service ). As part of the client - server concept, another program, the client, use this service. The communication between client and server depends on the service, ie the service determines which data is exchanged between the two. The server is ready to respond at any time to contact a client can. In contrast to the client, the active requests a service, the server is passive and waits for requests. The rules of communication for a service (format, call the server, and the importance of data exchanged between server and client data), are determined by a specific protocol for the service.
Clients and servers can run as programs on different computers or on the same computer. In general, the concept can be extended to a group of servers (software) that offers a set of services. Examples: mail server (extended ) web servers, application servers, database servers.
Since usually run collected in practice these servers on specific machines, it has become common to refer to this computer as a server itself. The same examples: mail server, web server, application server, database server.
Differences to peer -to-peer
In contrast to the peer-to- peer model, on which a program involved in the network is the client and server at the same time, are on the client -server model, the client and server components, separated and distributed to various programs.
Client- server system
A client -server system is a software (application system ) which make use of their duties and functions from the client - server model. In other words, the software is designed so that it can make use of the client-server model. The system therefore consists of at least two parts, a server and a client component that occur usually on different machines.
For example a client -server system having a central database server,