Usually we used the word Federated search – When we are
going the content outside the SharePoint Environment and which is not crawl in
our SharePoint Farm.
For example,
federation can provide search results from a web-search provider such as Bing,
or perhaps from a private data set that you do not have access to crawl.
Another
meaning of Federation:-
Federation can also be
a good solution for a geographically distributed organization that wants to
provide search access to content at its various locations when each location
has its own search index. Because each location provides search results from
its own index, it is not necessary to deploy a centralized search service that
builds and accesses a single, unified index.
In this context, federation can provide
advantages such as the following:
- Low bandwidth requirements ─ An organization that is geographically
dispersed might not have the high network bandwidth that is required to
crawl and index large amounts of remote content. When an organization uses
federation, the main data that is transmitted for search across the
wide-area network is only a set of search results from each federated
content repository.
- Freshness of search results ─ Each division within an organization can crawl
the local content more quickly than a centralized search deployment would
be able to crawl all of the content in the entire organization.
- Divisional search variability ─ When an organization uses federation, each
division within the organization can provide and control its own search
environment. Each division can tailor search to its own requirements and
preferences, with its own user experience and its own search connectors,
for example. A centralized search portal would not allow for such
differences.
- Limited size of search indexes ─ A large, geographically distributed
organization might have millions of documents. It might not be practical
for the organization to have a single, unified search index because of the
infrastructure that would be required to support such a large index.
Federation enables users in each division to perform a single search to
find relevant content that is distributed across multiple smaller search
indexes in the organization.
Comparing Federated Search to Content Crawling in
Enterprise Search
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 SharePoint Enterprise Search
By
querying the Search service application's content index for search results, you
can do the following:
·
Sort results by relevance.
·
Control how frequently the content index is updated.
·
Specify what metadata is crawled.
·
Perform a single backup operation for crawled content.
Advantages
of federating content with SharePoint Enterprise Search
By
using federated search to return search results:
·
You require no additional capacity requirements for the content
index, as content is not crawled by SharePoint Enterprise Search.
·
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.
You select this protocol
|
To get federated search
results from this kind of provider
|
Remote
SharePoint
|
The
index of a search service in another SharePoint farm
|
OpenSearch
1.0/1.1
|
An
external search engine or feed that uses the OpenSearch protocol, such as
Bing
|
Exchange
|
Exchange
Server 2013
|
Code
Sample to Federated Search SQL Server Connector
Added
Federated Search (i.e. Bing Search in to SharePoint Search)