An increasing number of organizations are finding that Web-based applications offer a solid cross-platform solution and that using them also enables the Internet as an excellent WAN infrastructure. However, many application vendors and programmers have been late in realizing the numerous benefits that Web-based applications offer over traditional platforms such as 32-bit Windows applications. Fortunately, Citrix’s NFuse technology provides the ability to Web-enable many of these “legacy” applications.

What is NFuse?
NFuse can best be described as an application portal. It lets organizations integrate and publish interactive applications into any standard Web browser. Basically, NFuse will allow access to a 32-bit Windows application via the Internet (or a corporate intranet) and a Web browser, thus making the application “Web-enabled.”

Best of all, NFuse is a free product. Well, to be more accurate, NFuse is offered at no charge to all Citrix MetaFrame customers. Why is it free? Citrix offers NFuse as a value-added product to enhance Citrix MetaFrame. And make no mistake—it does add value!

Technically, NFuse is a three-tier solution that includes a Citrix server component, a Web server component, and a Citrix client component with a Web browser. NFuse offers many features that will attract Citrix administrators. Some of the features offered by NFuse include:

  • Checking for the existence of an ICA client when connecting to an NFuse-based application for the first time. If an ICA client is installed, NFuse will check to ensure that the latest ICA client is installed. If not, the latest Win32 client will be downloaded and automatically installed.
  • Filtering and caching of an application set as opposed to grouping by user name. This action speeds up performance by allowing faster user logon and application access over the Web.
  • Fault tolerance by automatically contacting backup servers to query application data in the event of a server failure.
  • Support for UNIX applications when used with MetaFrame for UNIX, enabling users to access UNIX applications in a Web browser.
  • Support for multiple server farms, enabling administrators to publish applications to users from multiple MetaFrame for Windows and MetaFrame for UNIX server farms, all through a single Web page. This provides for increased access and availability to servers.
  • Elimination of the need for ICA clients to communicate with the ICA browser over UDP. This allows for more security by not opening up unnecessary ports on the firewall.

How it works
As mentioned above, an NFuse deployment involves the interaction of three network components, as illustrated in Figure A. The first component is an ICA client device (usually a workstation), the second is the Web server, and the third is a Citrix server farm.

Figure A
How NFuse functions

A Citrix server farm is a group of Citrix servers, managed as a single entity, that share some form of physical connection and a common base of user accounts. Important among a server farm’s standard capabilities is application publishing. Application publishing is an administrative task that lets Citrix server administrators expose specific applications hosted by the server farm on a per-user or group basis. This list of applications is commonly referred to as an application set.

The NFuse Web Site Wizard generates a login page on the Web server that lets users enter their username, password, and domain information. This information is passed to the Citrix server, which then determines which application set the user is authorized to access. This application set is presented to the user in a Web page. By selecting one of the authorized applications, the local ICA client on the device then establishes a connection to the appropriate Citrix server.

It is important to remember that the only role of Web servers in this process is to pass authentication information to the Citrix servers and return the appropriate application set to the user within his or her Web page. Once the application is selected by the user, all communication is between the ICA client device and the Citrix server. In an ICA client device, the Web browser and ICA client work together as a viewer and engine. The Web browser lets users view application sets while the ICA client acts as the engine that launches published applications.

Installing NFuse
NFuse 1.5 can be either downloaded from Citrix’s Web site or ordered on a CD. The entire program actually consists of a set of Web server extensions along with sample Web pages. NFuse includes separate setup programs for installing the Web server extensions on various Web servers, including Microsoft Internet Information Server, Netscape Enterprise Server, iPlanet, and Apache.

For demonstration purposes, we’ll take a quick look at a typical installation using IIS. (For more information on installing NFuse on other Web servers, see the Citrix NFuse Administrator’s Guide, which is included as part of the NFuse package.)

Be aware that during installation, the setup program will stop and restart the Web server and all of its associated services. Also, note that the MetaFrame XP setup offers administrators the option of installing NFuse during the MetaFrame installation. This option installs the Web server extension on the server and places a single NFuse Web site in the Web document root directory. The Web site provides a fully functional NFuse login page and can be used as-is with no additional configuration.

If you download NFuse from the Web site, you can copy the NFuseWebExt-IIS.exe file to your IIS server and execute it. The installation wizard will guide you through the installation. During the process, you must identify a Citrix server in your farm that will act as a contact point between the server farm and your Web server. If your server farm is composed of MetaFrame for Windows servers, you can specify the name of any server in the farm. MetaFrame for UNIX Servers requires the name of a server running the Citrix XML Services for UNIX.

The Web server extension setup program will then install example NFuse Web sites in a directory called Citrix\NFuse151 on your IIS server’s Web publishing root. Toward the end of the Web server extension installation, the setup program will prompt for the ICA Client CD or CD image. If you do not have the ICA client CD, you can download the appropriate clients from Citrix’s Web site.

When the installation is complete, you can use and/or modify one of the example Web sites or create your own using the Citrix Web Site Wizard. The Citrix Web Site Wizard is part of NFuse and can be accessed by running the file entitled NFuseWizard.exe from the CD or the Citrix download site. The Web Site Wizard contains many configuration options for customizing a Web site. Once you’ve set up the Web site for your NFuse applications, you are ready to begin accessing your published applications via a Web browser. Of course, if you are going through a corporate firewall, ensure that all necessary HTTP ports as well as Citrix ports are open.

Summing up
As you can see, the installation of NFuse in a properly configured Citrix environment is not a difficult process. Following these steps should have you well on your way to Web-enabling your line-of-business applications. Of course, there are numerous configuration options we didn’t touch on here, which are described in the 200-plus page Citrix NFuse Administrator’s Guide. When deployed correctly, NFuse can provide a secure, reliable, and personalized gateway to corporate applications and information from virtually any location.

How do you think NFuse can help your organization?

Have you already deployed Citrix NFuse? We look forward to getting your input and hearing about your experiences regarding this topic. Join the discussion below or send the editor an e-mail.