What Is A Server?

A server is a component that provides computer services to other components (typically called clients) via a network. Note that the term server, as well as the end client can be related both to the software component and to the hardware. Depending on the context, the term server can indicate:

1. A computer used to provide services to other computers, regardless of its hardware features
2. A computer belonging to a market segment dedicated to using as a server, characterized by high reliability and performance (like the Mac Pro or Xserve Apple)
3. A process (or a software program running) who provide services to other processes (e.g., Web server).

In general it tends to indicate how the server component that provides a service and client component that uses it.

Client-server or N-tier

The complex consists of one or more logical servers and, usually, several client is called client-server model. In recent years it has been extended to the ‘interaction between multiple machines or heterogeneous services, and in this case we talk about architecture in 3-tier (or more generally to N-tier).

The server receives requests from clients to service, and returns the results after they do the processing on. This allows you to concentrate on a central machine computing resources, software, maintenance, critical information or sensitive, the devices to ensure reliability (as backups). The clients, by contrast, can generally also machines with less resources and reliability, which have the sole task of interacting with the user, and do not contain critical information or sensitive.

Note that in terms of software a computer is never purely a server, as well as provide services to others is usually supports services provided by third parties, and thus is both server and client. For example, a mail server is supported by other servers (e.g., DNS server) for information on the net, and then is simultaneously an E-Mail server and client with regard to other services related to network management.

Services Provided By A Server

Among the services that are typically provided by a server, include:

• * File servers, allowing users to access files located on the server as if they were on your computer, facilitating the sharing of information
• Database server
• Web server
• Application server, where the server is used to run an application program and sharing capabilities among users
• Print server, allowing the pooling of one or more printers between users on a network with the possible management of access rights,
• Mail server, to manage email
• Game servers, which host resources to enable multiplayer games online
• Managing a computer network, local or geographic

or DHCP for automatic assignment of IP addresses to computers
or DNS servers that provide name resolution sites (for example it.wikipedia.org) in their IP addresses

• Server or graphic display server – see X Window System
• Server Authentication, which allows you to authenticate access to other resources
• FTP server provides network access to public folders or authentication
• VNC server provides, via a VNC client for a remote control
• Proxy server, provides a highly scalable Web access and the ability to control authentication (ACL) and filter

Reliability And Security Of A Server

The server is a key element of IT infrastructure to which it belongs, as its failures affect all clients that use it. Therefore, for the servers take precautions to ensure reliability and safety:

• Use of upper-class hardware with high performance and redundant elements (RAID disks, redundant power supplies)
• Power protection with UPS
• Physical protection by locating in a special room with restricted access (“server room”) or hosting in a server farm
• Connect the network preference, higher-capacity, redundant
• Conditioning
• Operating system configurations to ensure greater reliability and security (hardening)
• Management by expert systems

The computers are designed to be used as a server in a server room for medium-large are made so that they can be mounted in a rack.

The major investment required by these devices are motivated by the importance that the proper functioning of the server for its users.

Server Cluster

If the load of requests is excessive for a single server, or if you need high levels of reliability, multiple servers may divide the task of providing a service or service group. In this case, we say that the servers form a single computational resource defined as a server cluster, which may continue to operate even if a certain number of machine components is put offline, although obviously the resource deteriorates the overall performance. This requires that they be provided with a suitable operating system, and / or linked through specific network configurations.

Study: From Wikipedia, the free encyclopedia. The text is available under the Creative Commons.