Independent Computing Architecture
Encyclopedia
Independent Computing Architecture (ICA) is a proprietary protocol
for an application server
system, designed by Citrix Systems
. The protocol lays down a specification for passing data between server and clients, but is not bound to any one platform.
Practical products conforming to ICA are Citrix's WinFrame
, Citrix XenApp (formerly called MetaFrame/Presentation Server), and Citrix XenDesktop products. These permit ordinary Windows
applications to be run on a suitable Windows server, and for any supported client to gain access to those applications. Besides Windows, ICA is also supported on a number of Unix
server platforms and can be used to deliver access to applications running on these platforms. The client platforms need not run Windows; for example, there are clients for Mac
, Unix, Linux
, and various Smartphones. ICA client software is also built into various thin client
platforms.
ICA is broadly similar in purpose to window servers such as the X Window System
. It also provides for the feedback of user input from the client to the server, and a variety of means for the server to send graphical output, as well as other media such as audio, from the running application to the client.
Key challenges of such an architecture are network latency
and performance—a graphically intensive application (as most are when presented using a GUI
) being served over a slow or bandwidth-restricted network connection requires considerable compression and optimization to render the application usable by the client. The client machine may be a different platform, and may not have the same GUI routines available locally—in this case the server may need to send the actual bitmap data over the connection. Depending on the client's capabilities, servers may also off-load part of the graphical processing to the client, e.g. to render multimedia content. ICA runs natively over TCP port 1494 or may be encapsulated in Common Gateway Protocol (CGP) on TCP 2598. ICA supports the concept of channels at a session layer
to encapsulate rich media redirection or USB extension within ICA.
A more complete list can be found at: comparison of remote desktop software.
Proprietary protocol
In telecommunications, a proprietary protocol is a communications protocol owned by a single organization or individual.-Enforcement:Proprietors may enforce restrictions through patents and by keeping the protocol specification a trade secret...
for an application server
Application server
An application server is a software framework that provides an environment in which applications can run, no matter what the applications are or what they do...
system, designed by Citrix Systems
Citrix Systems
Citrix Systems, Inc. is a multinational corporation founded in 1989, that provides server and desktop virtualization, networking, software-as-a-service , and cloud computing technologies, including Xen open source products....
. The protocol lays down a specification for passing data between server and clients, but is not bound to any one platform.
Practical products conforming to ICA are Citrix's WinFrame
Citrix WinFrame
WinFrame was a multi-user version of Windows NT 3.51 which was fully repackaged by Citrix Systems. At this stage of the product development Citrix Systems licensed the Windows NT 3.51 base operating system from Microsoft. The core development that Citrix delivered was the MultiWin engine. This...
, Citrix XenApp (formerly called MetaFrame/Presentation Server), and Citrix XenDesktop products. These permit ordinary Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
applications to be run on a suitable Windows server, and for any supported client to gain access to those applications. Besides Windows, ICA is also supported on a number of Unix
Unix
Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...
server platforms and can be used to deliver access to applications running on these platforms. The client platforms need not run Windows; for example, there are clients for Mac
Macintosh
The Macintosh , or Mac, is a series of several lines of personal computers designed, developed, and marketed by Apple Inc. The first Macintosh was introduced by Apple's then-chairman Steve Jobs on January 24, 1984; it was the first commercially successful personal computer to feature a mouse and a...
, Unix, Linux
Linux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...
, and various Smartphones. ICA client software is also built into various thin client
Thin client
A thin client is a computer or a computer program which depends heavily on some other computer to fulfill its traditional computational roles. This stands in contrast to the traditional fat client, a computer designed to take on these roles by itself...
platforms.
ICA is broadly similar in purpose to window servers such as the X Window System
X Window System
The X window system is a computer software system and network protocol that provides a basis for graphical user interfaces and rich input device capability for networked computers...
. It also provides for the feedback of user input from the client to the server, and a variety of means for the server to send graphical output, as well as other media such as audio, from the running application to the client.
Key challenges of such an architecture are network latency
Lag
Lag is a common word meaning to fail to keep up or to fall behind. In real-time applications, the term is used when the application fails to respond in a timely fashion to inputs...
and performance—a graphically intensive application (as most are when presented using a GUI
Graphical user interface
In computing, a graphical user interface is a type of user interface that allows users to interact with electronic devices with images rather than text commands. GUIs can be used in computers, hand-held devices such as MP3 players, portable media players or gaming devices, household appliances and...
) being served over a slow or bandwidth-restricted network connection requires considerable compression and optimization to render the application usable by the client. The client machine may be a different platform, and may not have the same GUI routines available locally—in this case the server may need to send the actual bitmap data over the connection. Depending on the client's capabilities, servers may also off-load part of the graphical processing to the client, e.g. to render multimedia content. ICA runs natively over TCP port 1494 or may be encapsulated in Common Gateway Protocol (CGP) on TCP 2598. ICA supports the concept of channels at a session layer
Session layer
The session layer is layer 5 of the seven-layer OSI model of computer networking.The session layer provides the mechanism for opening, closing and managing a session between end-user application processes, i.e., a semi-permanent dialogue. Communication sessions consist of requests and responses...
to encapsulate rich media redirection or USB extension within ICA.
Client software
- Citrix ICA Client (Dos, OS/2)
- Citrix Presentation Server Client (Mac, Java)
- Citrix Receiver (Linux, Unix)
- Citrix XenApp Plugin (Windows)
- PXESPXESPXES also known as PXES Universal Linux Thin Client, created in early 2001 by Diego Torres Milano, is a Linux distribution designed to be run on thin clients using PXE. It is also possible to boot PXES from a CD-ROM or hard disk if the NIC or BIOS does not support PXE.A graphical tool guides the...
- rdesktopRdesktoprdesktop is a free, open source client for Microsoft's proprietary RDP protocol. It is released under the GNU General Public License and is available on Unix-like systems such as BSD and Linux....
- ThinstationThinstationThinstation is a free and open source Linux implementation of a thin client operating system. It only requires standard 32-bit x86 PC hardware and can boot directly from the network via PXE or Etherboot from a TFTP server, or from local devices such as Hard disks, CompactFlash drives, USB keyrings...
(through Citrix Receiver) - VMware ViewVMware ViewIn computing, VMware View is a commercial desktop-virtualization product developed by VMware, Inc. Its first two releases sold under the name VMware VDM, but with the 3.0.0 release in 2008VMware Inc. changed the name to "VMware View"....
A more complete list can be found at: comparison of remote desktop software.