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Windows Desktop Search (or '''WDS''') is an Indexed Search platform released by Microsoft for the Windows operating system. It was known as '''MSN Desktop Search''' prior to official release, and is sometimes referred to as such because of its inclusion in the MSN Search Toolbar when it was first launched. Version 2 is available for Windows 2000, Windows XP and Windows Server 2003, but Version 3 is only available for Windows XP and Windows Server 2003.1 Since version 3.0, the indexer runs as a Windows Service , so that a single index as well as a single instance of the service can be shared across all users - thereby improving performance. Windows Vista includes built-in indexed search capabilities out-of-the-box, known as Windows Search (also called Instant Search).2 Windows Search is based on Windows Desktop Search 3.0, and is API compatible with it. Windows 2000 through Windows Server 2003 also included an '' Indexing Service '' which also indexed the files on a hard drive. However, it lacked its own UI and had to be used with either the Windows Explorer search UI or an MMC snap-in. It also did not have word-wheeling capabilities. OVERVIEW Upon installation, Windows Desktop Search builds an index of the files on a user's hard drive. The initial creation of this index can take up to several hours, but this is a one-time event. Once the index is complete, Windows Desktop Search is able to use this index to search results more rapidly than it would take to search through all the files on your computer. Searches are performed not only on file names, but also on the contents of the file (provided a proper Handler for the file type is installed) as well as the keywords, comments and metadata the file might tagged with. For example, searching the computer for The Beatles would return a list of the Beatles music on the computer, as well as any e-mails and documents that include the phrase "The Beatles" in their titles or contents. WDS also features ''word-wheeled'' search (or ''search-as-you-type''). It begins searching as soon as characters are entered in the search box, and keeps on refining and filtering the search results as more characters are typed in. As an advantage, this results in finding the required files even before the full search text is entered. Windows Desktop Search supports advanced queries as well, expressed via the ''Advanced Query Syntax'' (AQS).3 AQS defines certain keywords which can be used to refine the search query, such as specifying boolean operations on searched terms (AND, OR, NOT) as well as to specify further filters based on file Metadata or file type. It can also be used to limit results from specific information stores like regular files, offline files cache, or email stores. File type specific operators are available as well.4 WDS also supports Wildcard searches.5 WDS by default include handlers for most common filetypes, including Word Documents , Excel Spreadsheets , PowerPoint Presentations , HTML Documents , text files, MP3 and WMA music files, WMV , ASF and AVI videos, JPEG , BMP and PNG images, among others.6 WDS also supports IFilter s, which is a Defined Interface that can be implemented by vendors of unsupported format. Once a file format has an associated IFilter, WDS uses the IFilter to extract the text of the document to index it.7 It uses ''property handlers'' to handle metadata from file formats. A property handler needs a property description and a schema for the property for WDS to index the metadata.8 ''Protocol handlers'' are used for indexing specific data stores. For example, files are accessed using ''File System Protocol Handler'', Outlook Datastores using the ''Outlook Protocol Handler'' and IE Cache using the ''IE History/Cache Protocol Handler''.9 WDS provides an API to let other applications leverage the indexing and searching capabilities. Using this API, applications can request search based on particular parameters (including restricting the search to only a few file types or data store) on either the entire index or a subset of it; the results will be presented to the application, which can then either present it to the user or apply further processing on it. WDS 3.0 also adds the ability for applications to ''push'' items to it for indexing, rather than waiting for it to come and index. Microsoft Office Outlook 2007 , as well as Microsoft Office OneNote 2007 uses this ability to index the items managed by them and use WDS search capabilities to provide the in-application searching features. As such, they require WDS 3.0 (or Windows Search in Windows Vista) to be installed and running to use the enhanced search capabilities within the applications. The WDS functionality is exposed via a Taskbar mounted deskbar. It provides a text field to type the query and the results are presented in a flyout pane. It also includes a Windows Explorer window as well. On selecting a file in the Explorer window, a preview of the file is shown in the right hand side of the window, without opening the application which created the file. Web searches can be initiated from both interfaces, but that will open the browser to search the terms using the default search engine. The WDS deskbar also has the capability to create application aliases, which are short strings which can be set to open diiferent applications. This functionality is accesssed by prefixing the ! character to the predefined string. For example ''"!calc"'' opens the Windows Calculator . This feature can also be used to create shortcut for URLs, which when entered, will open the specified URL in browser. It can also be used to send parametrized information over the URL, which are used to create search aliases. For example, ''"w text"'' can be configured to search ''"text"'' in Wikipedia . WINDOWS SEARCH See also The Windows Search platform in Windows Vista is based on WDS 3.0 and includes all functionality provided by it. It is also API compatible with it, so that applications using WDS will work with Windows Search as well. The indexed search functionalty is provided by the ''Windows Search'' Service . The indexer performs the I/O operations with Low Priority , the process also runs with low priority. As a result, whenever other processes require the I/O bandwidth or processor time, it is able to pre-empt the indexer, thereby significantly reducing the performance hit associated with the indexer running in the background. Windows Search service runs three processes to provide the search functionality:10 #SearchIndexer.exe, which maintains the index and decides which files require indexing. #SearchProtocolHost.exe, which hosts the protocol handler. It runs with the least permission required for the protocol handler. For example, when accessing filesystem, it runs with the credentials of the system account, but on accessing network shares, it runs with the credentials of the user. #SearchFilterHost.exe, which hosts the IFilter and property handlers to extract metadata and textual content. It is a low integrity process, which means that it does not have any permission to change the system settings. So, even if it encounters files with malicious content, they cannot use the search subsystem to cause lasting damage to the system configuration. Windows Search also includes a number of features that are not available with WDS. Unique to Windows Vista over Windows Desktop Search on Windows XP are the following:
Windows Search can also natively search the feed store of Windows RSS Platform , thus being able to search downloaded Web Feeds natively. It also natively supports the file types used by the in-built applications in Windows Vista. Natural language search is also supported and so the user can search for things like "photo taken last week" or "email sent from Dave". However, this is disabled by default.11 Natural language search uses expresses the queries in ''Natural Query Syntax'' (NQS), which is the natural language equivalent of AQS. The Windows Search index can also be accessed programmatically using both Managed as well as Native code.12 Native code connects to the index catalog by using a ''Data Source Object'' retrieved from Windows Vista shell's Indexing Service OLE DB provider. Managed code use the ''MSIDXS'' ADO.NET provider with the index catalog name. A catalog on a remote machine can also be specified using a UNC path. The criteria for the search is specified using a SQL -like syntax. The search functionality is exposed using the search bars in the start menu and the upper right hand corner of the Windows Explorer windows, as well as Open/Save dialog boxes. When searching from the start menu, the results are shown in the start menu itself, overriding the recent used programs. And searching from the search bars in Explorer windows replaces the content of the current folder with the search results. When searching from the start menu, it is also possible to launch an application by searching for its executable image name or display name. In the control panel, the search bar in the window can also search for control panel options. There is also a ''Search Explorer'', which is a special Windows Explorer screen that is used for searches. It presents UI graphically to set the parameters from some advanced operators without using AQS. However, unlike WDS, Windows Search does not support creating aliases. |
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