Publishing Applications in a Server Farm

Citrix MetaFrame 1.8 provides the new Program Neighborhood feature, a terrific service that displays applications that you publish from a server farm. This new feature works with servers running Windows NT Server 4.0, Terminal Server Edition with the MetaFrame 1.8 add-on or Citrix WinFrame 1.8. To make the most of the Program Neighborhood feature, you need to know what server farms are and why MetaFrame users should care about them. Next, you'll need to know how to set up a server farm, how to publish applications in it, how to manage the servers in a server farm, and how to get applications to the client.

What Is a Server Farm?
Citrix originally called a collection of load-balanced terminal servers a server farm. With MetaFrame 1.8, Citrix expanded the meaning to a management concept. From the administrator's perspective, a server farm is an organization of Terminal Servers running MetaFrame 1.8 or servers that are running WinFrame 1.8 and that you can manage from one console. From the user's perspective, a server farm makes applications published from terminal servers in a network accessible from what seems to be one server.

If you're thinking, "Wait a minute! A server running MetaFrame 1.0 can publish individual applications!" you're right. In a sense, Terminal Server also can publish individual applications because you can cause a Terminal Server session to display an application alone and terminate the session when the user closes the application. To connect to an application published from a server running MetaFrame 1.0 or Terminal Server, however, a user must establish an explicit connection to the server providing the application.

Using server farms to publish applications is different from using either MetaFrame 1.0 or Terminal Server. MetaFrame 1.8 provides access to all the applications in a server farm from one interface, without any reference to the terminal server that has the application loaded. To run applications published from a server farm, a user connects to the server farm, not to a specific server. The server in the server farm providing that application picks up the user request for a connection and runs the application. Users who connect to multiple applications served from different servers in the server farm will have active sessions on more than one server without knowing or needing to know which server is providing the applications.

From the user's perspective, the difference between publishing applications from unassociated servers in a domain and publishing applications from a server farm corresponds to the difference between a workgroup and a domain. In a workgroup, individual servers share resources, but you need to explicitly log on to each server to use those resources. In a domain, you can log on to one server and gain access to all shared resources. Like domains, server farms let administrators manage network resources from one location. But unlike domains, server farms don't offer one-stop authentication. If the application requires authentication for access, you have to provide your name and password for each application in the server farm. Still, the logical grouping is domainlike.

Why Use Server Farms?
The main reason to use server farms is to simplify published-application management and use. Server farms make life easier for administrators and users.

Server farms make network administration easier because, from one server, you can manage all the applications that the servers in a server farm publish, and switch the focus from server to server. Unless you're lucky enough to have all your terminal servers plugged into a keyboard/video/mouse (KVM) switch, you'll appreciate not having to wander from server to server to twiddle published-application settings. Also, the domain-centric model of MetaFrame 1.0 lets you designate application access to users and groups from only one domain, whereas publishing applications in a server farm lets you grant access to members of other domains without having to publish the application twice.

Server farms provide easier application access for users because the application distribution is transparent. Server farms let you push applications to users in the form of an application set. After users install an Independent Computing Architecture (ICA) client that supports MetaFrame 1.8, they can connect to the application set from the desktop's Program Neighborhood. Users will see the applications (including the same application icons that display for locally installed applications) that they have access to use. The only catch is that the Program Neighborhood is available for only Win32 clients (unless you create an ICA Passthrough Session); so other clients can't benefit from server farming.

Creating a Server Farm
Before you set up the server farm, you need to keep a couple of things in mind. First, you can simplify your life if you keep the server farm servers in the same domain and subnet. The servers don't need to be otherwise logically or physically grouped to cooperate. With support from WinFrame's ICA Gateway feature, you can configure the servers to be in different domains and on different subnets. Because server farms depend on one source of authentication (e.g., the domain controller if you organize the servers in a domain), server farms with more than one server must be organized into domains, and workgroup-based server farms can contain only one server.

Second, load balancing and server farming aren't synonymous. You can easily confuse using server farms and load balancing because of Citrix's previous references to load-balanced terminal servers as a server farm. But MetaFrame 1.8 server farms don't automatically provide load-balancing services, which send user application or logon requests to the least busy terminal server. You can incorporate Citrix's Load Balancing Services, which is sold separately, into a server farm. Later, I'll point out where load balancing can be a useful supplement to a server farm. If you want to use load balancing in a server farm, the servers need to be in one domain because server farms rely on a single user-authentication database for the entire farm.

You need to complete the following tasks to create a server farm:

• Install NT 4.0, Terminal Server Edition (server farms don't require Service Pack 4—SP4—but do support it).
• Install MetaFrame 1.8.
• Install the applications that each server in the server farm will publish.
• Group the terminal servers into the server farm.

The first task is straightforward. To install MetaFrame 1.8, follow the wizard and provide the licensing information. The trick to installing applications for a multiuser environment is installing them from Control Panel's Add/Remove Applications dialog box to make sure that the applications install for all users.

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