IFilters
Encyclopedia
An IFilter is a plugin that allows the Windows Indexing Service
and the newer Windows Desktop Search to index different file format
s so that they become searchable. Without an appropriate IFilter, contents of a file cannot be parsed and indexed by the search engine. IFilters are also used by SQL Server
as a component of the SQL Server Full Text Search service.
IFilter is designed to help users to index a large number of documents and then quickly find text within these documents. The documents can be files, email attachments or database records.
Windows Indexing Service, MSN Desktop Search, Internet Information Server, SharePoint Portal Server, Windows SharePoint Services (WSS), Site Server, Exchange Server, SQL Server and all other products based on Microsoft Search technology support indexing technology. Hereafter, we use term "search engine" to refer to these products.
An IFilter acts as a plug-in for full-text search engines. A search engine usually works in two steps:
During Step 1, the search engine itself doesn't understand format of a document. Therefore, it looks in windows registry for an appropriate IFilter and finds the IFilter. IFilter understands the document format. It filters out embedded formatting and extracts text from the document and return text back to the search engine.
Windows indexing service
Indexing Service was a Windows service that maintained an index of most of the files on a computer to improve searching performance on PCs and corporate computer networks. It updated indexed without user intervention...
and the newer Windows Desktop Search to index different file format
File format
A file format is a particular way that information is encoded for storage in a computer file.Since a disk drive, or indeed any computer storage, can store only bits, the computer must have some way of converting information to 0s and 1s and vice-versa. There are different kinds of formats for...
s so that they become searchable. Without an appropriate IFilter, contents of a file cannot be parsed and indexed by the search engine. IFilters are also used by SQL Server
Microsoft SQL Server
Microsoft SQL Server is a relational database server, developed by Microsoft: It is a software product whose primary function is to store and retrieve data as requested by other software applications, be it those on the same computer or those running on another computer across a network...
as a component of the SQL Server Full Text Search service.
IFilter is designed to help users to index a large number of documents and then quickly find text within these documents. The documents can be files, email attachments or database records.
Windows Indexing Service, MSN Desktop Search, Internet Information Server, SharePoint Portal Server, Windows SharePoint Services (WSS), Site Server, Exchange Server, SQL Server and all other products based on Microsoft Search technology support indexing technology. Hereafter, we use term "search engine" to refer to these products.
An IFilter acts as a plug-in for full-text search engines. A search engine usually works in two steps:
- The search engine goes through a designated place, e.g. a file folder or a database, and indexes all documents or newly modified documents, including the various types documents, in the background and creates internal data to store indexing result.
- A user specifies some keywords he would like to search and the search engine answers the query immediately by looking up the indexing result and responds to the user with all the documents that contains the keywords.
During Step 1, the search engine itself doesn't understand format of a document. Therefore, it looks in windows registry for an appropriate IFilter and finds the IFilter. IFilter understands the document format. It filters out embedded formatting and extracts text from the document and return text back to the search engine.
External links
- Filter Central — Microsoft Search Filters Discussion Board;
- IFilter at MSDN — Interface documentation on MSDN;
- IFilter.org — Downloads and documentation;
- MSG IFilter — IFilter for Outlook Message Files (.MSG) for Windows Desktop Search;
- IFilterShop — Some IFilters available as free for non-commercial users.
- IFilter Explorer Displays all the IFilters currently installed on your computer.
- PDF IFilter Foxit PDF IFilter. Works on Windows OS.
- Adobe PDF IFilter Adobe PDF IFilter. Works on Windows OS.
- PDFlib TET PDF IFilter PDF IFilter from PDFlib. Works on Windows OS.
- Windows Search connector for IBM Lotus Notes.