Citrix Virtual Apps

from Wikipedia, the free encyclopedia

Citrix Virtual Apps (formerly XenApp ) is a thin client solution from Citrix and the market leader in this area. The software relies on the terminal server functionality of Microsoft Windows - Server operating systems , making possible the use of centrally provided applications with different devices ( terminals ) that only the user interface have provided.

Versions

WinView

After a first Citrix product called Multiuser , based on the OS / 2 operating system licensed by Microsoft , appeared in 1991 , the company released WinView in 1993 , again an OS / 2 extended by multi-user capabilities.

WinFrame

After it became clear that the future belonged to Windows instead of OS / 2, a product called WinFrame was brought onto the market in 1995 as a complete multi-user operating system based on Windows NT 3.51, which is now licensed by Microsoft . The first time it contained the core technology MultiWin and the ICA - Protocol for the transmission of screen data to the client .

Citrix was already working on WinFrame 2.0 based on Windows NT 4.0 , which appeared in 1996 , when Microsoft decided to bring its own multi-user system onto the market and to refuse Citrix the necessary licensing for their (then competing) product. In order not to have to acquire the necessary multiuser know-how itself, Microsoft bought the necessary program code from Citrix.

MetaFrame

Based on the Citrix program code, Microsoft launched the multiuser operating system Windows NT 4.0 Terminal Server Edition in 1998 . Since the company did not buy the ICA protocol from Citrix, its own protocol, the RDP protocol (based on the T.120 protocol), has been used to transfer data to the client since then .

Citrix converted the technological lead that still existed over Microsoft, namely the ICA protocol and load balancing capabilities, into an add-on product for Microsoft's new terminal server, which is how MetaFrame was created . Version 1.8 of this also served Windows 2000 Server ; MetaFrame XP then also supported Windows Server 2003 .

Presentation Server

After the appearance of the already mixed version, MetaFrame Presentation Server 3.0 , the product range was redesigned in version 4.0; the central component within the "Citrix Access Suite" was now only called Citrix Presentation Server .

With “Citrix Access Essentials”, a version that was around 60% cheaper was available for individual servers for the first time.

XenApp

In 2008 the product line was renamed XenApp with version 5.0 , the current version is XenApp 7.15 . There is also a variant XenApp for UNIX 4.0 (for HP-UX , Solaris and AIX ).

XenApp is available in three versions (editions):

  • Advanced (for small and medium-sized environments)
  • Enterprise (for larger environments)
  • Platinum (for particularly complex or very large environments)

With version 7, the previous IMA architecture ( Independent Management Architecture ) was replaced as the technical basis by the new FMA architecture ( FlexCast Management Architecture ).

Virtual apps

The product has been called Virtual Apps since 2018 and is available in three editions:

  • default
  • Advanced
  • Premium

Architecture and functions

The Citrix solutions are not a replacement, but an extension of the Terminal Services of the Windows Server. Therefore, Microsoft Remote Desktop Services licenses must also be purchased for use. Compared to the Terminal Services of the Windows Server, the Citrix products offer more options for central administration and management of the Terminal Server (central administration console), the ICA protocol is used instead of RDP.

With the published applications individual applications can be made available to an end user, which behave like locally installed programs. In reality, however, only the screen content of the terminal server is transmitted to the client; the application runs entirely on the server. With Microsoft Terminal Services, this option has only been available since the introduction of Windows Server 2008.

With the shadowing ("mirroring") a built-in help desk functionality is available, which gives the administrator the possibility to view the screen of the user and to provide assistance. In the fat client environment, comparable programs are e.g. B. pcAnywhere or VNC .

The Load Balancing allows to distribute user sessions depending on the current server utilization (CPU load, network or disk access, etc.) to multiple servers in a farm.

The Resource Manager monitors a large number of hardware and software parameters of the Citrix servers and can send various types of notifications if threshold values ​​are exceeded in order to notify administrators of potential problems in good time.

The Network Manager is an extension of the SNMP interface to integrate existing monitoring solutions such as HP OpenView or IBM Tivoli .

The Installation Manager facilitates the installation of applications on a large number of servers. An installation is "recorded" on a reference server and a package is created from it. Installation Manager then distributes this package to other servers in the farm.

The current versions contain the universal printer , which means that the printer drivers for all printers that may be used no longer have to be installed on the terminal servers. The Universal Printer intercepts the EMF data that a printing application normally sends to the printer driver. This data is then compressed and sent to the Citrix client on the workstation via the ICA session. There the Citrix client forwards the data to the locally installed printer driver. This technique is currently only available for Windows workstations. A universal printer is used on other platforms, which is significantly slower and generates larger spool files.

The so-called application isolation environment ( AIE) is included in the “Enterprise” license variant . Using this technology, programs can be run on terminal servers which, due to registry access or access to the file system, could not be run on terminal servers or only to a limited extent. The AIE function virtualizes access to the registration database, the file system, named pipes etc. and redirects them so that separate areas are available for each user and each application. In this way, for example, several versions of applications such as Microsoft Office can be published on one server.

Application streaming is available from version 4.5 to version 6.5 . This technology consistently continues the application isolation and also uses the method on workstations. Administrators can make applications available centrally as packages. If a workstation wishes to use the program published in this way, the package is automatically downloaded and the program can be used locally on the respective PC. Using this technology, centrally published applications can also be used offline. This is an alternative to the classic application distribution.

Importance of working with Microsoft

Citrix and Microsoft have been working together in the area of ​​terminal server solutions since 1989 and are important strategic partners. Citrix gets an insight into the program code of Microsoft Windows Server, in return Microsoft gets access to the XenApp program code.

See also

literature

swell

  1. ↑ Citrix Historical Retrospective 1989-2010 (PDF; 74 kB) Citrix Systems, Inc. November 4, 2010. Accessed December 11, 2017.
  2. ↑ Citrix Product Definitions . Citrix Systems, Inc. Retrieved January 15, 2013.
  3. ^ Brian Madden: Citrix launches the Citrix Technology Professional program, their version of the Microsoft MVP . June 17, 2006. Retrieved January 9, 2013: “The box I'm holding in my hand is a genuine copy of“ Citrix Multiuser ”—Citrix's first official shipping product. It shipped on February 1, 1991. It was a multiuser edition of Microsoft OS / 2 v1.21. "
  4. ↑ Chris Broomes: Configuring Citrix MetaFrame XP for Windows: Including Feature Release 1 . Syngress, May 10, 2002, ISBN 978-1-931836-53-1 , p. 26 (accessed August 27, 2013): “In 1995, Citrix unveiled its WinFrame product, the first one to combine MultiWin technology, the ICA protocol, and the Windows NT operating system. "
  5. ^ Citrix and Microsoft (1989-1998). Citrix Blogger, October 15, 2006, accessed January 6, 2012 .
  6. ↑ citrix.de: Citrix Virtual Apps and Desktops (formerly XenApp and XenDesktop)

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