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Crawlers (Webcrawlers)

Let's learn more about them now! 

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msnbot

Msnbot was a web-crawling robot (type of internet bot), deployed by Microsoft to collect documents from the web to build a searchable index for the MSN Search engine. It went into beta in 2004, and had full public release in 2005. The month of October 2010 saw the official retirement of msnbot and its replacement by bingbot*.

http://en.wikipedia.org/wiki/Msnbot

  
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* bingbot -bingbot is a web-crawling robot (type of internet bot), deployed by Microsoft to supply Bing (search engine). It collects documents from the web to build a searchable index for the Bing (search engine). It replaced msnbot as the main Bing Crawler on October 2010.

A typical user agent string for bingbot is " Mozilla/5.0 (compatible; bingbot/2.0; +http://www.bing.com/bingbot.htm)". This appears in the web server logs to tell the webmaster who is requesting a file. Each webmaster is able to use the included agent identifier, "bingbot", to disallow or allow access to their site (by default access is allowed). If they don't want to grant access they can use the Robots Exclusion Standard to block it (relying on the assumed good behaviour of bingbot), or use other server specific means (relying on the web server to do the blocking).^{http://en.wikipedia.org/wiki/Bingbot}

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Googlebot

Googlebot is the search bot software used by Google, which collects documents from the web to build a searchable index for the Google search engine. When you search for sites that display your IP, you will often see the googlebot's IP address.

If a webmaster wishes to restrict the information on their site available to a Googlebot, or another well-behaved spider, they can do so with the appropriate directives in a robots.txt file, or by adding the meta tag <meta name="Googlebot" content="nofollow" /> to the web page. Googlebot requests to Web servers are identifiable by a user-agent string containing "Googlebot" and a host address containing "googlebot.com".

Currently Googlebot only follows HREF links and SRC links. Googlebot discovers pages by harvesting all of the links on every page it finds. It then follows these links to other web pages. New web pages must be linked to other known pages on the web in order to be crawled and indexed or manually submitted by the webmaster.

A problem which webmasters have often noted with the Googlebot is that it takes up an enormous amount of bandwidth. This can cause websites to exceed their bandwidth limit and be taken down temporarily. This is especially troublesome for mirror sites which host many gigabytes of data. Google provides "Webmaster Tools" that allow website owners to throttle the crawl rate.
http://en.wikipedia.org/wiki/Googlebot

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FAST Crawler

is a distributed crawler, used by Fast Search & Transfer, and a general description of its architecture is available.

http://en.wikipedia.org/wiki/Web_crawler

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Methabot

is a scriptable web crawler designed for flexibility and speed. It is free software written in C, distributed under the terms of the ISC licence.

Methabot has wide support for customization. It can be scripted using Javascript with E4X, configured using its own configuration language, and dynamically switch configuration while running.

Key features

Scriptable using Javascript
Provides MySQL bindings to Javascript
Support for the Robots Exclusion Standard
User-defined filetype filtering and sorting, according to custom rules
Heavy multi-threading
Chaining of custom parsers
Converts HTML to real XML for E4X compatibility

http://en.wikipedia.org/wiki/Methabot

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PolyBot

is a distributed crawler written in C++ and Python, which is composed of a "crawl manager", one or more "downloaders" and one or more "DNS resolvers". Collected URLs are added to a queue on disk, and processed later to search for seen URLs in batch mode. The politeness policy considers both third and second level domains (e.g.: www.example.com and www2.example.com are third level domains) because third level domains are usually hosted by the same Web server.

http://en.wikipedia.org/wiki/Web_crawler

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RBSE

was the first published web crawler. It was based on two programs: the first program, "spider" maintains a queue in a relational database, and the second program "mite", is a modified www ASCII browser that downloads the pages from the Web.

http://en.wikipedia.org/wiki/Web_crawler

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World Wide Web Worm

was a crawler used to build a simple index of document titles and URLs. The index could be searched by using the grep Unix command.

http://en.wikipedia.org/wiki/Web_crawler

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Yahoo! Slurp

Yahoo! Slurp is a web crawler from Yahoo! that obtains content for the Yahoo! Search engine. Slurp is based on search technology Yahoo! acquired when it purchased Inktomi.

Slurp identifies itself by using the following User agent strings:

 * Mozilla/5.0 (compatible; Yahoo! Slurp; http://help.yahoo.com/help/us/ysearch/slurp)
 * Mozilla/5.0 (compatible; Yahoo! Slurp China; http://misc.yahoo.com.cn/help.html)

http://en.wikipedia.org/wiki/Yahoo!_Slurp

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WebFountain

is an Internet analytics engine implemented by IBM for the study of unstructured data on the World Wide Web. IBM describes WebFountain as:

. . . a set of research technologies that collect, store and analyze massive amounts of unstructured and semi-structured text. It is built on an open, extensible platform that enables the discovery of trends, patterns and relationships from data.

The project represents one of the first comprehensive attempts to catalog and interpret the unstructured data of the Web in a continuous fashion. To this end its supporting researchers at IBM have investigated new systems for the precise retrieval of subsets of the information on the Web, real-time trend analysis, and meta-level analysis of the available information of the Web.

Factiva, an information retrieval company owned by Dow Jones and Reuters, licensed WebFountain in September 2003, and has been building software which utilizes the WebFountain engine to gauge corporate reputation. Factiva reportedly offers yearly subscriptions to the service for $200,000. Factiva has since decided to explore other technologies, and has severed its relationship with WebFountain.

WebFountain is developed at IBM's Almaden research campus in the Bay Area of California.

http://en.wikipedia.org/wiki/WebFountain

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WebRACE

is a crawling and caching module implemented in Java, and used as a part of a more generic system called eRACE. The system receives requests from users for downloading web pages, so the crawler acts in part as a smart proxy server. The system also handles requests for "subscriptions" to Web pages that must be monitored: when the pages change, they must be downloaded by the crawler and the subscriber must be notified. The most outstanding feature of WebRACE is that, while most crawlers start with a set of "seed" URLs, WebRACE is continuously receiving new starting URLs to crawl from.
http://en.wikipedia.org/wiki/Web_crawler

[harihan]

Nice information. Thanks for sharing.


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[MSL]

Nice information. Thanks for sharing.


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  Harihan is Harihan; SEO is SEO; SEO services are SEO services, but...Crawlers | Web crawlers are Crawlers | Web crawlers  and we should continue this crawler, SEO topic.

 

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WebCrawler

was used to build the first publicly-available full-text index of a subset of the Web. It was based on lib-WWW to download pages, and another program to parse and order URLs for breadth-first exploration of the Web graph. It also included a real-time crawler that followed links based on the similarity of the anchor text with the provided query.
http://en.wikipedia.org/wiki/Web_crawler