Independent Computing Architecture

Independent Computing Architecture (ICA ) is similar to Microsoft's RDP is a proprietary protocol for a Terminal Server / Application Service Providing system, which was developed by Citrix Systems. The protocol defines a specification established to transfer data between servers and clients, but is not tied to any particular platform.

The application products ICA -compliant include the Citrix XenApp editions. These allow ordinary Windows programs on a suitable Windows server (or, ungebräuchlicher: Unix-like programs on a suitable [eg Solaris ] Unix- server) to run, and with any supported client access these applications. The client platform does not need to run on Windows. Example, there are clients for Macintosh and Unix.

ICA is similar to Window servers such as the X Window System in general terms, but has a wider range of applications. However, it also leads to the retransmission of user inputs and restricted ( eg access to local drives, voice input by microphone, ...) on terminal outputs from the client to the server as well as a variety of means for the server to to transmit audiovisual outputs from the running application to the client.

One of the key challenges for such an architecture is performance. A graphics-intensive application ( which is normal with a GUI applications presented the case) sets high standards for compression and optimization, so that the application for the client is usable. This is especially true when the application has a slow network connection must be provided. ICA requires very little network bandwidth, 10-20 kbit / s in a typical session. ( Called Speedscreen to XenApp 5, XenDesktop HDX from XenApp 6.0 & 5.0) This, together with performance-enhancing protocol extensions it can also be used with narrow-band network connections (eg, ISDN or GPRS) in contrast to RDP.

Because the client need not be a Windows platform, must and he can not use Windows graphics libraries available locally. The server must be transferred in this case, the pure image data and in addition all other data ( such as files from USB sticks ) over the relatively slow network connection.

• Network protocol at the application layer