Query Web Service FAST serach sharepoint 2010 – Tutorial - Dig SharePoint

Query Web Service is the integration point for applications outside your SharePoint environment, such as standalone, non – web – based applications or Silverlight applications running in a browser. The Query web service is a SOAP – based web service and supports a number of operations, including:
Querying and getting search results Getting query suggestions Getting metadata (managed properties) The same schema is shared by SharePoint Search and FAST Search, and both products support the same operations. For querying, clients can easily switch the search provider by setting a ResultsProvider element in the request XML. A number of extensions are available for FAST Search, for example, refi nement results, advanced sorting using a formula, and issuing queries using the FAST Query Language.

Some other important things you need to know are  –
The Query RSS Feed –
Certain scenarios, such as simple mash – ups, may need only a simple search result list. The RSS feed is an alternative, lightweight integration point for supplying applications outside of SharePoint with a simple RSS result list. The Search Center — the default search frontend in SharePoint 2010 — includes a link to a query – based RSS feed. Switching the engine to the RSS format is done simply by setting a URL provider. Because it was designed to be simple, there are some limitations to what
can be returned and customized in the Query RSS feed. The user object models or web service integration scenarios are recommended for more advanced applications.

The Query Object Model
This is the lowest – level object model, used by the Federation Object Model, the Query web service, and the Query RSS feed. Both SharePoint Search and FAST Search support the KeywordQuery object in this object model. While the Federation OM returns XML (to web parts), the Query OM returns data types.