What does web crawler technology mean?

Web crawler technology refers to the technology that automatically captures World Wide Web information according to certain rules. Web crawlers are also known as web spiders and web robots. In the FOAF community, they are more commonly known as web page chasers; other less commonly used names include ants, automatic indexing, simulation programs, or worms.

Web crawler technology refers to the technology that automatically captures World Wide Web information according to certain rules

Web crawler (also known as web spider, web robot, more commonly known as web chaser in the FOAF community) is a program or script that automatically crawls World Wide Web information according to certain rules. Other less commonly used names include ants, autoindexers, emulators, or worms.

The description and definition of the crawl target are the basis for determining how to formulate web page analysis algorithms and URL search strategies. The web page analysis algorithm and candidate URL sorting algorithm are the key to determining the service form provided by the search engine and the crawler web page crawling behavior. The algorithms of these two parts are closely related.

Existing focused crawler descriptions of crawling targets can be divided into three types: based on target web page characteristics, based on target data patterns, and based on domain concepts.

Based on the characteristics of the target web page

The objects captured, stored and indexed by crawlers based on the characteristics of the target web page are generally websites or web pages. According to the method of obtaining seed samples, it can be divided into:

(1) Pre-given initial crawling seed sample;

(2) Pre-given web page classification directory and corresponding to the classification directory Seed samples, such as Yahoo! classification structure, etc.;

(3) Catch target samples determined by user behavior, divided into:

(a) Catch that displays annotations during user browsing Take samples;

(b) Obtain access patterns and related samples through user log mining.

Among them, the webpage characteristics can be the content characteristics of the webpage, or the link structure characteristics of the webpage, etc.

Based on the target data pattern

Crawlers based on the target data pattern target the data on the web page. The captured data generally must conform to a certain pattern, or can Convert or map to target data schema.

Based on domain concepts

Another way to describe is to establish an ontology or dictionary of the target domain, which is used to analyze the importance of different features in a certain topic from a semantic perspective degree.

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