Maintaining a Microsoft Project 2000 Installation, страница 3

The source list contains the locations searched by the installer for installation packages. The entries in this list can be network locations, Uniform Resource Locators (URLs), or local media such as a CD. If one of these sources fails, Windows Installer can quickly and seamlessly try the next.

Windows Installer manages the source list per installed product. Thus Microsoft Project 2000 has a separate source list than another software product such as Microsoft Word. However to improve performance the installer stores source list data in the registry at the following location.

Source lists are product specific. Information required to build a source list is stored in SourceList key below the {ProductCode} key for the product. This guarantees a unique source list for each product. The key resides in the Hkey_Current_User hive so that it follows the user that has user-assigned roaming profiles.

On Microsoft Windows 2000, the registry location for the source list is different. It resides in the following location: HKEY_Local_Machine\Software\Classes\Installer\Products\{PackageCode}\SourceList

Last Used Source

To ensure fast access to network install sources, the last successfully used source is a value directly under the {ProductCode}\SourceList key. This way, a single key is all that needs to be opened in most common cases.

There are three types of sources: Media, Network and URL. The LastUsedSource is specified via an ordered source type (N, M, or U) and integer index within the particular list for that type. For example:

“M;3;d:\project\bin”

“N;1;\\installpoint\applications\office\project\bin”

“U;2;http//www.Microsoft.com/office/project/bin”

You should note that a “source” is a fully qualified path to a folder, not a fully qualified path to an installer package. Entries in the source list are folder paths. The name of a package, which is appended onto a source, is stored separately as the PackageName value. For all sources in a particular source list belonging to a product, the package name is identical.

List of Network Sources

In addition to the LastUsedSource values in the registry, the installer maintains a list of alternative install points. This list is used in the event that the LastUsedSource install point is not available. The list of network sources is stored in the following registry key:

<Index> is the first positive integer not already in use as a value name in the network list. Any attempt to add more than 26 network sources to the list is ignored. A sample list of network sources might contain the following values:

List of Media Sources

Another class of install sources is media. There is never more than a single source in the Media SourceList since it is assumed that there is only one form (CD or otherwise) of source media. (In the case of product installed via multiple disks, however there are multiple entries in the Media SourceList.)

While Microsoft Project 2000 ships on one CD, it is important to understand that other Microsoft products may ship on floppy disk, and the installer uses multiple entries in the Media Sourcelist to keep track.