What is Web Scraping & Why It is Used?
What is web scraping?
Web is a connecting network that links global community together. Scraping stands for extraction. Together the both terms imply extraction of data from the World Wide Web (www).
Undoubtedly, the market has shifted its ground from offline to online. So, escalating the flow of information has become mandatory. Every commercial entity is pushing the boundaries. What they want is information. Web scraping is cracking this nut for them. And the vision of semantic web is its one of the ultimate mottos.
Semantic web is defined as a common framework the removes all barriers in sharing and reusing the data across any application or organization.
Actually, scraping of web is a modern technology to extract a piece of information. It transforms an unstructured data into the structured format. Before that, relevancy parameter is fixed. Then, the big data is browsed for extracting information.
How and Why Web Scraping?
Let’s beat the bushes to learn the techniques of how scraping is done on web.
Manually copying and pasting: Consider this example. To identify the number of schools in New York for national survey, I will delve into web searching. Google the query: Putting my query into the search bar of Google, its SERP will pop up various results. Therefore, I’ll copy and paste the data from the relevant link to fulfill my requirement.
Unix’ text grepping: Using UNIX grep command, the web developers extract data from any application on internet. The developers can capitalize on the matching of regular expression of programming languages.
HTTP programming: Recovery of the lost static or dynamic webpages can be possible through HTTP programming. Web developers use socket programming to send request to the remote web server through HTTP programming. This techniques repatriates the loss occurred due to lost data on the website.
HTML parser: The dynamic layout of the website is in. Such layouts are created through a source file of data. That similar data is encoded for designing dynamic pages.
Data mining process banks on wrapper. It is a program that spot, scan and then, extract the content. Subsequently, the scrapped content is molded into relational data. This is what a wrapper called. It spots the common template on which dynamic layout is prepared. Thereafter, wrapper induction system recognizes a URL. Besides, XQuery and HTQL can also serve the same motto.
Document Object Model (DOM) parsing: Retrieving the scripts from the dynamic layout on the browsers, like internet explorer and Mozilla, can be possible with DOM parsing. The web browsers resolve and describe their syntactic roles in to DOM tree. Thereby, web scraping services involve scrapping of dynamic web pages to extract data.
Software for web-scraping: There are numerous software available for eliminating the manual efforts of a web developer. They automatically recognize and crack through the coding of the dynamic web pages. Some in-built scripting functions in them peel the data off and then, transform it into structured format. Hence, a local data base gets prepared by the software.
Web-page analyzers using vision of computer: Stronghold on machine language in association with computer vision can let you extract what you want from the web.
Capturing semantic annotation: Webpages contain metadata or semantic markups and annotations. These carry brief of the specific page in the form of data snippets. The scrapper can utilize DOM parsing for scanning annotations of the web pages for extracting data. And if the information lies in semantic layers, the scraper can capitalize on data schema as well as instructions from the semantic layers.
Vertical aggregation platforms: Many of the commercial entities works on vertical aggregation platforms. These are the auto-generated multiple bots for nullifying the human involvement. These bots supply repositories of knowledge to a specific arena or vertical. It helps in extracting quality information and then, delivers it to the thousands in the vertical. These are subjected to the long tail sites which are hard to crack through.