The IIS metabase
The IIS metabase plays a major role in your Web server's configuration. However, since Microsoft introduced the metabase in IIS 4.0, little in-depth information has been available about what goes on inside metabase.bin. In this issue, I introduce you to the IIS metabase, then explain what it stores and how to edit and customize its settings.
The metabase is a hierarchical database that stores IIS configuration values. With the introduction of the metabase, Microsoft transferred the most IIS-related settings from the registry to the metabase and added many more settings that allow greater customization. Microsoft made this change in part to let the system take advantage of features that the registry doesn't support. For example, because the metabase contains only settings related to IIS, it's physically smaller than the registry. This smaller size lets the system maintain a copy of the metabase in memory for faster access.
Another improvement is that the metabase supports a Lightweight Directory Access Protocol (LDAP) interface. LDAP is a set of standard interfaces that Active Directory Service Interfaces (ADSI) supports. ADSI uses a set of common objects and interfaces to access directories and other hierarchical data structures. Some might say that just having a standards-based interface rather than the registry access functions is a big improvement; however, the real plus is that ADSI lets you build utilities that let you access and edit the metabase remotely. But before I get into the details of editing, let's review how to protect your metabase.
Protecting Your Metabase
One of the worst things that can happen to IIS is the destruction or corruption of the metabase. Therefore, you need to know how to back up your metabase. To begin the backup process, open Internet Services Manager (ISM). Beneath Internet Information Services, right-click your computer name, then select Backup/Restore Configuration. On the Configuration Backup/Restore dialog box, which Figure 1, page 2, shows, click Create backup. Provide a short but meaningful name for your backup. When you click OK, the system will create the backup file in the \system32\inetsrv\metaback directory.
The second way to protect your metabase is to hide it. When you hide the metabase, you protect it from anyone who might gain unrestricted file-level access to your system. I recommend renaming your metabase something less tempting than the default metabase.bin. After all, how interesting does recipes.imb look in the \my documents\recipes directory? The IIS installation process creates metabase.bin in your \system32\inetsrv directory. Moving the metabase requires you to restart IIS either before renaming or after creating a copy of the metabase.
Use the registry to tell IIS the new name and location of the metabase. (Always back up the registry before making changes.) Open a registry editing tool, and add the MetadataFile (REG_SZ) value to the HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\InetMgr\Parameters subkey. This value must contain the full path, including drive letter and filename, to your relocated and renamed file. Also, don't forget to remove or replace your original metabase file and move the backup copy you created.
Accessing Metabase Settings
You can use several methods to edit the metabase. Those methods include
- The ISM/Microsoft Management Console (MMC) Internet Information Services snap-in (For an explanation of the distinction between ISM and the MMC snap-in, see the Web-exclusive sidebar "ISM and the MMC Internet Information Services Snap-in.")
- The MMC Microsoft Site Server Configuration Console snap-in
- Command-line command execution
- Programming interfaces (i.e., IMSAdminBase and ADSI-GetObject)
- MetaEdit
The MMC snap-ins are application components that allow limited access to the metabase. Notice the two programming interfaces that are available. The first programming interface is the IIS Admin Base Object (IMSAdminBase), which is Active Template Library (ATL) compatible. IMSAdminBase is ideal for retrieving data from the metabase. However, because IMSAdminBase isn't an ADSI-based interface, carefully consider any decision to create a custom metabase property. (Creating custom properties is an involved process and beyond the scope of this article.) More information about the IMSAdminBase interface is available from the Microsoft Developer Network (MSDN) Online Library (http://msdn.microsoft.com/library/ default.asp?url=/library/psdk/iisref/abre6bol.htm).
The second programmatic interface is ADSI-GetObject. This interface works well for accessing most objects (keys) and values (properties) that make up the metabase. Unfortunately, the ADSI interface has limitations. For example, some entries created with the IMSAdminBase interface aren't ADSI compatible. In addition, installing Site Server or Microsoft Commerce Server 2000 adds several properties that the ADSI interface has trouble setting and retrieving.
An example of where you can use the ADSI objects is in the command-line interface to the metabase. This interface is a set of script files that exists in the \inetpub\adminscripts directory in Windows 2000 and in the \system32\inetsrv\adminscripts directory in Windows NT 4.0. The most generic of these scripts is adsutil.vbs. Microsoft articles often reference this script when you need to check or modify a specific metabase setting that isn't available from ISM.
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