Microsoft Indexing Service

Indexing Service is a Microsoft Windows 2000 base service for file systems and Web servers. Formerly known as Index Server, its original function was to crawl and create a catalog–similar to the index created by SharePoint Portal Server–of the content of Internet Information Services (IIS) Web servers. Indexing Service now creates catalogs for the contents and properties of both file systems and virtual Web sites.

As an operating system component, Indexing Service targets the same wide range of customer scenarios that Windows targets. Indexing Service targets the desktop experience. It provides an enhanced search experience for individual users covering information stored on local disks. You access Indexing Service in Windows when you click the Search button in the Start menu, when you press CTRL+F, when you click the Search button in Windows Explorer, and when you click the search task pane in Office XP. Indexing Service exposes management and query objects that allow rapid development of custom search applications. You can expand Indexing Service catalogs to contain information from remote file shares. Such custom applications can serve vertical applications or groups of users. These custom applications can crawl information from multiple locations.

Indexing Service also offers full-text search from Internet sites. You can use Indexing Service to drive custom search Web applications. In addition to query language support, Indexing Service offers a full range of programmability features targeted for the custom-application developer: scripting objects for query and administration, an OLE DB provider, and ADO compatibility.

The following list describes the components of Indexing Service.

• Data access. Indexing Service does not include a cross-protocol gathering component. It can access any data that is available from the file system, including local file systems and shared file systems on remote computers. Indexing Service facilitates crawling of Web site content to create an index by using the IIS metabase to understand which files map to Web site content. Indexing Service then follows the information from the IIS metabase to crawl the local Web sites. Indexing Service does not use the HTTP protocol to crawl Web sites. Therefore, Indexing Service cannot crawl content that is rendered dynamically, such as ASP pages referencing a database or personalized content that changes for each user.
• Filters. Indexing Service uses filters installed on the operating system, including the MIME filter for news and e-mail, the Office filter for Office documents, and the HTML filter.
• Ranking. Indexing Service uses ranking algorithms based on the vector space model. The default algorithm used is the Jaccard formula. For more information about the specific algorithms, see Appendix B.
• Schema support. Indexing Service provides rich, broad schema support. By using SharePoint Portal Server Administration in Microsoft Management Console (MMC), users can view all properties indexed from documents and can indicate which properties to store in the property cache for fast retrieval.
• Extensibility and programmability. Indexing Service provides a platform for full-text search applications. It includes a full set of programming interfaces, including scripting interfaces for administration and query and an OLE DB provider for searches. For information about Indexing Service programming interfaces, see Appendix B.
• Query languages. Indexing Service provides rapid access to files through flexible querying language. Indexing Service supports Query Dialect 1, Query Dialect 2, and SQL full-text extensions.

For a list of features new to Indexing Service 3 included with Windows 2000, see Appendix B.

Indexing Service is the performance solution for the need in custom application development to provide full-text search over content of an Internet site. It is less appropriate for applications where the data is primarily structured. Developers of such applications should consider Microsoft SQL Server 2000. For ease of use without need for customization, or for applications that require aggregation of content from various sources and source types, SharePoint Portal Server is the appropriate choice.

Indexing Service is an optional operating system component. The initial creation of indexes of file system contents can be resource-intensive and can affect desktop application performance. Therefore, Windows does not enable Indexing Service by default.