Federated Search Overview
Federated Search Server 2008 provides two approaches for processing queries to return search results: Content crawling In this approach, results are returned from the search server's content index based on the user's query. The content index contains content that is crawled by the search server, and includes text content and metadata for each content item. Federated search In this approach, you are enabled to display search results for additional content that is not crawled by your search server. With federation, the query can be performed over the local content index, or it can be forwarded to an external content repository where it is processed by that repository's search engine. The repository's search engine then returns the results to the search server. The search server formats and renders the results from the external repository within the same search results page as the results from search server's own content index.
Comparing Federated Search to Content Crawling in Search Server 2008
To help you decide whether to crawl a repository's content directly or by using federated search, you should consider the differences between the two approaches. You must determine which is most appropriate based on the content repository, and your requirements for the search results you want to return. There are advantages to both approaches.
Advantages of crawling content with Search Server
By querying the search server's content index for search results, you can do the following:
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Sort results by relevance.
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Control how frequently the content index is updated.
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Specify what metadata is crawled.
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Perform a single backup operation for crawled content.
Advantages of federating content with Search Server
By using federated search to return search results:
- You require no additional capacity requirements for the content index, as content is not crawled by search server.
- You can take advantage of a repository’s existing search engine. For example, you can federate to an Internet search engine to search the Web.
- You can optimize the content repository's search engine for the repository's specific set of content, which might provide better search performance on the content set.
- You can access repositories that are secured against crawls, but which can be accessed by search queries.
Federated Locations
A federated location defines the federated search connection to the external content repository, and is composed of the following:
- Location type
- Query and More Results link templates
- Triggers
- Display information
- Restriction
- Authentication and credentials information