A webmaster, marketer, SEO specialist, pricing specialist regularly needs to extract data from website pages in a form convenient for further processing. In this article, we will understand what technology is used to collect data, what kind of process it is, and why it has several names.
Most often, the collection of data from web resource pages is called parsing or scraping.
Let's figure out what these processes are, and is there a difference between them.
Initially, an application that performs two operations: downloading the necessary information from the site and analyzing the site's content was called parsing.
"Parsing" is a grammatical analysis of a word or text. This is a derivative of the Latin "pars orationis" - a part of speech.
Parsing is a method in which information is parsed and broken down into components. The received data is then converted into a suitable format for further processing, during which one data format is converted into another, more readable one.
Let's say the data is retrieved in raw HTML, and the parser takes it in and converts it into a format that can be easily parsed and understood.
Parsing uses a toolkit that extracts the desired values from any data format. The extracted data is stored in a separate file on the computer/in the cloud or directly in the database. This is a process that starts automatically.
Further analysis of the collected information is carried out by special software.
What does it mean to parse?
A parser is a software solution, while parsing is a process. A typical site scraping process consists of the following sequential steps:
‣ Identification of target URLs.
‣ If the website being crawled for data collection uses anti-parsing tools, then the parser selects a suitable proxy server to get a new IP address through which it sends its request. If necessary, the captcha solving service is activated.
‣ Sending GET/POST requests to these URLs.
‣ Search and locate required data in HTML code.
‣ Transform this data into the desired format.
‣ Transfer of the collected information to the selected data storage.
‣ Export data in the required format for further work with them.
Over time, the process of downloading the necessary information from the site and analyzing the content of the site began to be divided into two independent operations. The term crawler was coined. The crawler is engaged in bypassing the site and collecting data, and the parser is engaged in content analysis.
Later, the term scraping was coined. Web scraping combines the functions of a crawler and a web scraper.
Here is Wikipedia's definition of web scraping:
Web scraping is a technology for obtaining web data by extracting it from web resource pages. Web scraping can be done manually by a computer user, however the term usually refers to automated processes implemented with code that makes GET requests to the target site.
Web scraping is used to syntactically transform web pages into more usable forms. Web pages are created using text-based markup languages (HTML and XHTML) and contain a lot of useful data in the code. However, most web resources are intended for end users and not for automated usability, so technology has been developed that "cleanses" web content.
Loading and viewing a page are critical components of the technology, they are an integral part of the data sampling.