A client ( German "customer", and client- side application or client application) means a computer program that runs on the user's computer. They are integrated into a rule in a client-server communication.
The counterpart to the client, the server-side applications.
An important group of client-side applications, the browser, such as Firefox, Microsoft Internet Explorer or Safari, which use the HTTP protocol for data communication with a web server to query from this data and then render it to the user.
Another example is e -mail clients: please contact to an e -mail server to fetch emails from him and send him. The client does not have to be constantly in use or connected to a network, because the mail server receives incoming e -mails.
The Ajax - concept found in client-side applications that are embedded in web pages, a growing importance. Other client applications that have their own proprietary client-server protocols are, for example, or the Citrix client SAP.
Most often occur client-side applications in a mixed form to a server-side application.
Client-side vs.. server-side state saving
It is important in the context, as the context of a user session can be saved. For example, HTTP is stateless ( stateless ), so you can remember any data between two data requests to the server principle. A client-side application can use the cookie concept to store information on the client side, which are read by a client-side scripts consequence at a later point in time. However, cookies do not offer any form of data security and can be read, for example, non-application of Spyware. This functional gap is partially closed by the concept of a server-side session management.
The stateless Client-/Server-Communication itself thus becomes a system in which the data session can be maintained on the server a plurality of data requirements. This will be possible (eg password protected ) sessions.
- To fix some problems ( validity of form inputs ) can be dispensed with the cooperation of the Web server.
- Allowing a dialog with the user.
- The aesthetics of the website can be improved (eg changing content and presentation depending on the mouse position ).
- The source code is visible and accessible to the user. This may be undesirable under certain circumstances.
Types of clients
A distinction is conventional fat client (also rich or smart clients) and thin clients (even lean or slim clients).
As clients are also referred to all those computers in a network, in contrast to the servers that provide no services.
- IT architecture
- Web Development
- Software Architecture