Web application publishing.

Run any app on the Web. Now!

Citrix NFuse

TechnicalWhite Paper

March 31, 2000

Citrix NFuse Technical White Paper

Introduction to Citrix NFuse

The Internet has changed the way the world competes. Simply put, applications must be available via the Internet to users every-where, inside and outside the organization, using a standard Web browser. With NFuse™, Citrix’s new application portal technology, you have the power to integrate and publish interactive applications into any standard Web browser.

To publish applications you simply create application portals with the Citrix NFuse Web portal wizard or simplified scripts. You define the applications set specific to each user or group and the application portal is dynamically created. When the portal is accessed from a Web browser, the user clicks on the desired application, it opens in the browser and works as if it were a local application.

With NFuse from Citrix, you can enhance your users’ computing experience with the power to personalize which applications users receive. You can even personalize the browser and content around the applications, by user, if you choose. Plus, you retain the ability to manage applications using all the powerful capabilities of Citrix MetaFrame for Windows 2000 Servers. It’s the ultimate way to run existing apps on the Web. Now.

NFuse brings a new user interface to the application deployment process. This new interface uses Java object technology executed on a Web server to dynamically create an HTML-based presentation of the applications published in the Citrix server farm for a specific user.

NFuse is both a developer’s tool and a Web master’s application. NFuse includes an application programming interface and an easy-to-use wizard: the API lets you create customized Web server scripts from scratch to meet the requirements of your environment while the wizard creates scripts for you to use as-is or modify according to the NFuse API.

NFuse places control over the application deployment process in the hands of the administrator. Using the NFuse API, an administrator can configure all Citrix Independent Computing Architecture (ICA) session options on the Web server without ever visiting the user’s desktop.

Benefits of Deploying NFuse:

  • Enhances the user’s web browser experience by providing the means to access and deliver any application via a web browser without special HTML, scripting, Java or other proprietary means.
  • Provides total control to the web author or application provider to customize the user interface and easily integrate into existing corporate intranet, or application hosting portal.
  • Extends Citrix’s Application Launching & Embedding (ALE) technology through dynamic content adjustment without web author modification.
  • Provides the ability to integrate standard HTML content with managed server-based application deployment using Citrix’s Independent Computing Architecture (ICA).
  • Provides total control to the web author or application provider to customize the user interface, provide personalized content, application access, and be easily integrated into existing corporate Intranets, Extranets or application portals.

NFuse Features

  • Web interface to Citrix Program Neighborhood. Now users of almost any ICA Client can benefit from the simplified application access provided by Citrix Program Neighborhood.
  • Dynamic user interface creation. NFuse lets you create a single “template” Web script that Web servers can dynamically customize for each user.
  • Complete administrative control over application deployment. NFuse’s use of Web server-side scripting lets you configure all ICA Client options in server-side scripts and ICA files.
  • Integration with popular Web technologies such as XML. In addition, NFuse’s COM-compliant Java objects can be accessed from various Web server scripts, such as Java Server Pages and Microsoft’s Active Server Pages.
  • Simplified script writing. For those administrators not familiar with Web server scripting, NFuse includes proprietary HTML extensions. You can use these HTML extensions to write Web server scripts without requiring knowledge of any scripting languages or scripting models, such as VBScript and Active Server Pages.
  • Web Site Wizard. NFuse’s Web Site wizard creates complete NFuse-enabled Web sites. The Web Site wizard contains many configuration options for customizing your Web site.
  • Enhanced security, NFuse eliminates the need for ICA Clients to communicate with the ICA Browser over UDP.

Provide personalized content and access to applications with Citrix NFuse

Deploying NFuse

A NFuse deployment involves the interaction of three network components:

  • Citrix server farm
  • Web server
  • ICA Client device

Citrix Server Farm

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 per-user group basis. Users can connect and initiate ICA sessions when a Citrix server administrator publishes an application for a group of users.

With the advent of MetaFrame 1.8 and WinFrame 1.8, the Citrix server farm added Program Neighborhood to application publishing. Program Neighborhood or Program Neighborhood Services automates the client-side configuration process by eliminating the need for administrators or ICA Client users to browse the network for published applications. Using a Program Neighborhood-capable ICA Client, any user can authenticate to the farm and receive a list of user-specific published applications. This list of applications is called an application set.

With NFuse, the Citrix server farm functions as an application serving back-end. In this role, the server farm performs two important duties:

  • Supply application set information. The Citrix server responds to requests by NFuse for application set information. The server farm exports that information to NFuse for formatting into HTML pages that a user can view in a Web browser.
  • Host applications. At a user’s request (when the user clicks a link in a Web page), the server farm hosts an ICA session containing the requested application for the user.

NFuse adds a software component called NFuse Services to the Citrix server farm. This NT Service functions as the communication point between the server farm and NFuse’s Web server component.

Web Server

The Web server hosts the NFuse Java objects. The NFuse Java objects are a group of COM-compliant Java objects that you can call from Web server-side scripts to perform several tasks that are important to publishing applications. The NFuse Java Objects perform the following services:

  • Authenticate users to a Citrix server farm
  • Retrieve per-user application sets from a server farm through XML
  • Give you the ability to modify the properties of individual applications before presenting them to users
  • Create .ICA files that user’s can access to start ICA sessions

The NFuse Java objects are added to your web server as part of the Citrix Web Server Extension. This installation program also adds two examples Web sites containing server-side scripting that you can use to give your users access to their application sets.

In addition, NFuse includes the Web Site Wizard, which creates customized Web sites that you can use as-is or modify to fit your requirements. The wizard lets you create various types of Web sites, including sites based on Microsoft’s Active Server Pages model or sites based on Citrix’s own extensions to HTML.

ICA Client Device

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 (created by server-side scripting in a NFuse Web site) while the ICA Client acts as the engine that launches published applications.

NFuse supports many Web browser/ICA Client combinations. For a complete list of browser/client combinations, see “ICA Client Device Requirements” later in this document.

NFuse In Action

NFuse is an excellent solution for enterprises or application service providers (ASP’s) that wish to rapidly deploy windows applications across the internet, corporate intranets, or partner extranets. The following diagram describes the interaction between the Citrix server farm, NFuse Web server, and ICA Client device when deployed via the internet:

  1. An ICA Client device user visits a login page and enters a user name, domain, and password. The Web browser sends an HTTP request containing the user’s credentials to the Web server.
  1. The Web server reads the user’s information and uses the NFuse Java objects to forward that information to a designated Citrix server in the server farm using XML. This designated server acts as a broker between the Web server and the Citrix server farm.
  1. The designated Citrix server communicates with the native Program Neighborhood Service running on the servers in the farm to determine which applications the user can access based on his or her credentials. These applications comprise the user’s application set. The designated server then forwards the user’s application set information to the NFuse Java objects running on the Web server. The Web server uses the NFuse Java objects to generate an HTML page containing links to the applications in the user’s application set.
  1. The user initiates the next step by clicking one of the hyperlinks in the HTML page. The Web browser sends a request to the Web server to retrieve the referenced ICA file. The Web server passes this request to the NFuse Java objects, which retrieve a template ICA file that contains substitution tags. The Java objects replace the substitution tags in the template ICA file with information specific to the user and desired application. The Java objects then send the customized ICA file to the Web browser. ICA files are text files containing parameters that configure ICA session properties such as the application to run in the session, the address of the server that will execute the application, and the properties of the window to display the application in, among others.
  1. The Web browser receives the ICA file and passes it to a locally installed ICA Client.
  1. The ICA Client receives the ICA file and initiates an ICA session with a Citrix server according to the ICA file’s connection information.

Integrating Links to UNIX and Java Applications

By integrating NFuse technology, ALE, and MetaFrame for UNIX Operating Systems, you can enhance the NFuse application portal with links to Java and UNIX applications.

NFuse gives the user a dynamically created web page containing a set of ALE icons that are the same as the ones they get in Program Neighborhood.

MetaFrame 1.0 for UNIX does support ALE. It is possible to create links to ICA files on a web page that, when clicked, are downloaded to an ICA client and launch or embed a MetaFrame for UNIX Operating Systems published application. This is similar to how ALE and application publishing functioned in MetaFrame for Windows version 1.0 (prior to the new Program Neighborhood features in MetaFrame 1.8).

However, MetaFrame 1.0 for UNIX does not support Program Neighborhood today, and, until it does in future versions, you cannot use NFuse to dynamically create web pages containing Program Neighborhood icons for applications running on MetaFrame for UNIX servers.

Using a “template” web page, it is possible to use NFuse to create a web page that contains user-personalized icons for Windows apps and “static” icons for UNIX apps. A web page containing static links to ICA Files can be integrated with NFuse to allow the dynamic creation of NFuse content side-by-side with existing ALE links.

More information on creating ALE link for use with published applications can be found in the ICA Web Client Administrator’s Guide available at More information on MetaFrame for UNIX Operating Systems is available at

Program Neighborhood and NFuse will be fully supported by future versions MetaFrame for UNIX, providing full support for dynamically displaying application links to Window, UNIX, and Java applications.

NFuse System Requirements

To fully leverage the value of web-based application deployment, there are three required components, the Citrix Server, the Web Server, and the ICA Client Device in conjunction with a web browser.

Citrix Server Requirements

In order to participate in the NFuse system, your Citrix servers must meet the following requirements:

  • The Citrix server running NFuse Services must be a MetaFrame for Windows NT 4.0 Terminal Server Edition (TSE) Version 1.8 or MetaFrame for Windows 2000 Servers Version 1.8.
  • The remaining servers in the farm do not have to run any NFuse software but must support Program Neighborhood. Supported servers include any combination of WINFRAME 1.8, MetaFrame for Windows NT Terminal Server Edition(TSE) Version 1.8 and MetaFrame for Windows 2000 Servers Version 1.8 (a mixed group of WINFRAME and MetaFrame servers is supported).
  • All servers must be members of a server farm. A Citrix server farm is a group of Citrix servers managed as a single entity and that shares some form of physical connection and a common base of user accounts. You use the MetaFrame or WINFRAME tool Published Application Manager to administer server farms.
  • The servers in the farm must have applications published under the server farm management scope.

For information on server farm membership and publishing applications in a server farm, see the application publishing chapter in your MetaFrame Administrator’s Guide or the WINFRAME System Guide.

Web Server Requirements

The following Web Server environments are supported by NFuse:

  • Internet Information Server (IIS) version 4.0 running on Windows NT 4.0 Server
  • Internet Information Server version (IIS) 4.0 running on Windows NT 4.0 Terminal Server Edition
  • Internet Information Server version (IIS) 5.0 running on Windows 2000 Servers
  • Apache (with Apache JServ and GNU JSP support) on Linux RedHat 6.x
  • Apache (with Apache JServ and GNU JSP support) on Solaris
  • Netscape Enterprise Server on Solaris

Note: The version of IIS included with Microsoft Windows NT 4.0, Terminal Server Edition is 3.0. You must download and install a newer version of IIS, available from the Microsoft Web site.

ICA Client Device Requirements

In order to operate with NFuse, your ICA Client devices must have a recent ICA Client and a supported Web browser. The following table lists the Citrix ICA Client/Web browser combinations that you can use with NFuse. The ICA Clients listed below are all available for download from the Citrix Download site at For information on configuring these clients for NFuse, please see the Citrix NFuse Administrator’s Guide, also available from the Citrix web site.

The following table lists the minimum ICA Client version numbers that can be used with NFuse.

ICA Client / Version / Supported browsers
Win32 / 4.21.779 / Netscape Navigator 4.01 and above Internet Explorer 4.0 and above
UNIX / 3.0 / Netscape Navigator 4.01 and above Netscape Communicator 4.61 and above
Linux / 3.0 / Netscape Navigator 4.01 and above Netscape Communicator 4.61 and above
Web (ActiveX) / 4.21.779 / Netscape Navigator 4.01 and above Internet Explorer 4.0 and above
Web (Plug-in) / 4.21.779 / Netscape Navigator 4.01 and above Internet Explorer 4.0 and above
Win16 / 4.21.779 / Netscape Navigator 4.08 and above Internet Explorer 4.01 and above
Java – Applet / 4.11 / Netscape Navigator 4.01 and above Internet Explorer 4.0 and above
Java – Application / 4.11 / Netscape Navigator 4.01 and above Internet Explorer 4.0 and above
MAC / 4.10.23 / Netscape Navigator 4.01 and above Netscape Communicator 4.61 and above

It is important to note that the features and capabilities of each ICA Client differ. For information on supported ICA Client features, see The Citrix ICA Client Administrator’s Guide for the ICA Client in question.

Summary

Whether you are a CIO, CEO, Web Master, or IT manager, Citrix NFuse can have a huge impact upon your bottom-line. NFuse provides you with the ability to quickly take advantage of the internet, develop collaborative partnerships via extranets, and to have a better informed and more productive internal staff via a corporate intranet site. NFuse can provide you with “Webability”- the ability to run any application on the web and provide personalized content and access to applications in a highly manageable fashion.

To take the first step towards “webifying” your business, check out the NFuse product section on the Citrix web site at or contact your local Citrix representative.