Understanding Software Installation and Maintenance

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The Software Installation and Maintenance component of the IntelliMirror technologies is an extremely useful tool for administrators. It can be used to make applications available for installation from across the network (that is, to publish applications), to assign applications to certain groups or computers, or to uninstall applications installed using the tool.

Software Installation and Maintenance leverages Windows 2000's Group Policy and Windows Installer features to permit the easy deployment and management of applications in the enterprise. Here's how it works: To deploy an application, you edit the appropriate group policy and add the application's native Windows Installer package to the Software Installation and Maintenance user or computer policy, depending on whether you want it to apply to users or computers. (This process is described in more detail later in this chapter.) Group Policy then makes the application available to the appropriate group of users or computers. The next time a user logs on or a computer is rebooted, the policy is applied to the user or computer and the application either is automatically installed, is added to a list of installable programs in Add/Remove Programs, or is installed on first use from the Start menu. The new Windows Installer handles the automatic installation or uninstallation of all programs, as well as any upgrades or repairs.

Choosing an Installation Package Format

Before deploying an application using IntelliMirror, you need to decide whether to use a native Windows Installer package (if one is available for your application), to repackage the application, or to use a zero administration for Windows applications package (a .ZAP file).

If the application comes with a native Windows Installer package (one with an .MSI file extension), you can in many cases simply copy the package to the applications file share and add the package to the group policy. If you don't have a Windows Installer package for the application, the next best choice is to author your own installation package, using a commercial authoring package from InstallShield or WISE Solutions, or to repackage the application into a Windows Installer package. You can repackage applications with Seagate Software's WinInstall program, a light version of which is included with Windows 2000 Server. WinInstall is discussed later in this chapter.

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The Microsoft Office 2000 Server Resource Kit (available from Microsoft Press) includes an Installation Customization tool that allows you to create custom Windows Installer packages that you can deploy using IntelliMirror.

The last option for applications not natively authored for Windows Installer is to create a .ZAP file for the application—basically a special text file that points to the setup program for the application. This approach has some limitations. Because legacy applications that aren't repackaged can't take advantage of the Windows Installer service, .ZAP files are not able to do the following:

• Assign applications to users or computers. You can, however, publish applications with a .ZAP file, as described later.
• Install applications with elevated permissions. (Windows Installer gives higher permissions to installation programs to eliminate the need to always use an administrator account to install software.)
• Install applications automatically on first use.
• Perform a complete rollback of an unsuccessful installation or permit applications to repair themselves. (The application must be Windows Installer-aware to take advantage of the last feature.)

Deciding Whether to Publish or Assign

Another important decision to make when deploying applications is whether to publish them in Active Directory or assign them to users or computers. When you publish an application in Active Directory, it becomes available from Add/Remove Programs for those users to whom the group policy applies. Assigning an application to a user or computer makes the application available without any special action on the user's part. (Assigned applications appear on the Start menu and are installed on first use.) Table 24-2 summarizes the differences between publishing and assigning applications.

Table 24-2. Differences between publishing and assigning deployed applications

	Published Applications	Applications Assigned to Users	Applications Assigned to Computers
When after deployment is the software available for installation?	After the next logon.	After the next logon.	After the next reboot.
How is the software installed?	Via Add/Remove Programs in Control Panel.	On first use. (Icons are present on the Start menu and/or the desktop.)	The software is already installed.
Is the software installed when a file associated with the application is opened?	Yes.	Yes.	The software is already installed.
Can the user remove the software?	Yes, via Add/Remove Programs. (Reinstallation is also supported.)	Yes, although the software will become available again after the next logon.	No, although software repairs are permitted. Local administrators can uninstall software.
What package types are supported?	Windows Installer packages and .ZAP files.	Windows Installer packages.	Windows Installer packages.