A search appliance is a type of computer appliance

Computer appliance

A computer appliance is generally a separate and discrete hardware device with integrated software , specifically designed to provide a specific computing resource. These devices became known as "appliances" because of their similarity to home appliances, which are generally "closed and sealed" –...

 which is attached to a corporate network for the purpose of indexing the content shared across that network in a way that is similar to a web search engine

Web search engine

A web search engine is designed to search for information on the World Wide Web and FTP servers. The search results are generally presented in a list of results often referred to as SERPS, or "search engine results pages". The information may consist of web pages, images, information and other...

.

Architecture

A search appliance is usually made up of several components. These include a gathering component, a standardizing component, a data storage area, a search component, a user interface component, and a management interface component:

• The gathering component is usually a web crawler
  Web crawler
  A Web crawler is a computer program that browses the World Wide Web in a methodical, automated manner or in an orderly fashion. Other terms for Web crawlers are ants, automatic indexers, bots, Web spiders, Web robots, or—especially in the FOAF community—Web scutters.This process is called Web...
  
   or file crawler that goes out on a network or the Internet and gathers files and data from specified locations. This might include SMB shared directories, NFS shared directories, databases, and web pages. The crawler might either copy files to the search appliance, or only copy the metadata
  Metadata
  The term metadata is an ambiguous term which is used for two fundamentally different concepts . Although the expression "data about data" is often used, it does not apply to both in the same way. Structural metadata, the design and specification of data structures, cannot be about data, because at...
  
   about the file.
• A standardizing component takes the data from the gathering component and transposes it into a standardized format for storage in the data storage component. It then places it in the data storage area.
• The data storage component holds metadata about the files and might also contain copies of the actual file or data as well as the metadata about the file.
• The search component searches through the stored metadata from the files and provides the information to the search interface in the form of query results. It also can provide links to the copies of the files stored on the search appliance, or it can provide links to the original files in the source locations.
• The search interface is the component where users compose their search queries. It provides instructions to the search component and displays query results to the user.
• The management interface lets administrators manage user accounts, permissions, adding and deleting search indexes, crawl job scheduling, and other relevant functions.

Commercial examples

• Google
  Google
  Google Inc. is an American multinational public corporation invested in Internet search, cloud computing, and advertising technologies. Google hosts and develops a number of Internet-based services and products, and generates profit primarily from advertising through its AdWords program...
  
   has two SAs, one for large networks and one for smaller networks. They both use Google's proprietary indexing formula to display results in order of relevance. The way it finds data is very similar to Google Desktop Search. All the data that is to be indexed must be stored in a folder that would be accessible by a web browser. This means that each computer to be indexed must include a web server of some type or a copy of Google's computer indexing service (Google Desktop Search).

• The Fabasoft Mindbreeze
  Fabasoft Mindbreeze
  Fabasoft Mindbreeze is a range of software for Enterprise Search, Information Access and Digital Cognition. The flagship product of the range is Fabasoft Mindbreeze Enterprise...
  
   Appliance is an other example of an SA produced by the Austrian software vendor Fabasoft
  Fabasoft
  Fabasoft AG is a software manufacturer headquartered in Linz, Upper Austria. The company was established in 1988 by Helmut Fallmann and Leopold Bauernfeind.The name Fabasoft is an acronym of Fallmann Bauernfeind Software....
  
   Mindbreeze in cooperation with Dell
  Dell
  Dell, Inc. is an American multinational information technology corporation based in 1 Dell Way, Round Rock, Texas, United States, that develops, sells and supports computers and related products and services. Bearing the name of its founder, Michael Dell, the company is one of the largest...
  
  .

• The Perfect Search Appliance is a third example of an appliance that searches files. The appliance stores file metadata in an index on the appliance. A web server on the appliance uses that metadata to provide relevant search results in response to user queries, and provides a link to access the original files.