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This article mainly introduces what the general network crawler means, has a certain reference value, interested friends can refer to, I hope you have a lot of gains after reading this article, let Xiaobian take you to understand.

The structure of general web crawler can be roughly divided into page crawler module, page analysis module, link filtering module, page database, URL queue and initial URL integration. In order to improve work efficiency, general web crawler will adopt a certain crawler strategy. Common crawler strategies are depth-first strategy and breadth-first strategy.

Depth first strategy, the basic method is to visit the next web page link in order from low to high in depth, until it cannot be deepened.

After the crawler completes the crawling branch, it returns to the previous link node and further searches for other links. After all the links have been passed, the crawling task is over. This strategy is better suited to vertical search or site search, but crawling sites with deep levels of content can be a huge waste of resources.

2. Breadth-first strategy, which crawls web pages according to the depth of the content directory hierarchy, and the pages with shallow directory hierarchy are crawled first.

After the page crawling at the same level is completed, the crawler continues to drill down to the next level. This strategy can effectively control the crawling depth of the page, avoid the problem that crawling cannot end when branching at infinite depth, and is convenient to implement without storing a large number of intermediate nodes. The downside is that it takes a long time to climb to pages deeper in the directory hierarchy.

General web crawler is also called Scalable Web Crawler. Crawler objects extend from some seed URLs to the whole network, mainly collecting data for portal search engines and large web service providers. For commercial reasons, their technical details are rarely published. This kind of web crawler crawling range and quantity is huge, the crawling speed and storage space requirements are high, the crawling page order requirements are relatively low. At the same time, because there are too many pages to refresh, it is usually parallel, but it takes a long time to refresh the page. Although there are some defects, general web crawlers are suitable for a wide range of topics of search engines and have strong application value.

Thank you for reading this article carefully. I hope that the article "What is the meaning of general web crawler" shared by Xiaobian will be helpful to everyone. At the same time, I hope that everyone will support you more and pay attention to the industry information channel. More relevant knowledge is waiting for you to learn!

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