Web Scraping is a method used to extract raw data from websites and convert it into useful information. It’s a way for copying information in the internet and compiling it in a single database or datasheet for later use. Web scraping can be done in different kinds of ways depending on the information you require. The most common purpose of using web scraping is to analyze the raw data gathered and create a single database which provides an overlay of all the information needed by a user. So, how does web scraping work then?
The Key Processes
Web scraping involves two processes – fetching and extracting. Fetching is a way of getting web information by means of tools (which will be discussed later). This can be done by downloading the page of a website (actual interface) or by manually copying and pasting the data needed. Once the data is gathered, extraction takes place. Web scrapers will began searching, parsing, and formatting the information gathered to pick the data they need in building a database. In most cases, scrapers will only look for certain data within a website. An example is a method called extension scraping where users navigate the page source and find extension links of data they need.
Tools in Web Scraping
Scrapers use tons of tools (as mentioned earlier) in fetching and extracting web information. Some of which are the following:
Manual Copy-and-Paste. As the name implies, it is a process of copying and pasting all the raw data from a website into a database. This process is the most common yet the most tedious method in extracting data. Scrapers use this method when gathering small amounts of data from tons of websites.
Vertical Aggregation. This method uses bots to extract information from websites. They are used by companies in gathering information from certain websites without any human intervention throughout the process. Due to its limits, vertical aggregate-based systems are often measured by evaluating the data extracted. The more useful the data, the more valuable the system.
HTML Parsing. HTML-based web pages can only be extracted by the use of HTML-based software. By using the same kind of language, scraping will be much easier and faster, producing better results. HTML parsing works best in pages programmed under Java scripts and nested HTML languages. Scrapers use this to extract deeper information from the page such as links, backlinks, contact information, programming structure (in rare cases), resources, and so on.
HTTP Programming. This method is like HTML Parsing but instead of using HTML-based software tools, scrapers use HTTP extracting tools to target HTTP-based web pages. HTTP tools extract data and converts it into web browser data, and later into raw code.
Text Pattern Matching. This is a basic extracting tools for UNIX-based websites. Examples of these are PERL and PYTHON-based pages. These websites are commonly built from supercomputers to provide a smoother interface for users. Through this method, scrapers will be able to crack the website’s programming code and gather data in its purest form.
DOM Parsing. DOM (Direct Object Model) parsing is a very powerful tool when using Mozilla and Internet Explorer as your browser. These browsers often capture website scripts, allowing scrapers to easily fetch and extract the data straight from the browser without using any advanced tool. Though very effective, this method only works for generic websites and often malfunctions due to protective measures set by the website’s admin.
Semantic Annotation. This method works when websites are developed in a layered kind of way. This happens when a page uses metadata (which works like a layer) to provide an interface for users. By snipping those layers, scrapers will have an easier time fetching data. Semantic annotation is under the DOM-parsing method but due to its unique nature, experts often classify it as a different approach in scraping raw data.
Google Tools. Google Tools such as Google Sheets are also being recognized by scrapers because of its IMPORTXML†feature. This formula automatically extracts different data from other websites easily. This means that once the data changes, the data in the sheet will also change. This is perfect for constantly changing information such as price rates and fair values of goods, services, and stocks.
Xpath. XML also has its own kind of guidelines to follow. It uses a branch/tree-like structure to build a database inside the software. Xpath works by directly converting that structure into a form that the scraper prescribed. This is often combined with DOM to extract a whole website into a specific database.
Protected Websites and Web Scraping Systems
As you have probably realized by now, these scraping tools each have unique applications – and choosing among the tools depends on the target. But there are times in which websites are just plain scrape-proof. These are called protected websites. Such websites includes in their programming a protective command in case someone (except the admin) tries to fetch the programming information used in their web pages. Common web scraping tools won’t simply work in case of protective websites.
But it’s not the end of the world. By combining different tools, scrapers can still come up with a new way to fetch and extract data. Web Scraping tools, when combined, allows scrapers to create their own customized web scraping system. A customized system is proven highly effective against these protected websites as they allow scrapers to crawl deeper beyond the protective command and still fetch the information they need.
How does web scraping work? Well, at this point, you know the answer – and understanding how to use two or more methods will surely help you in fetching raw data in the future. Is it legal to fetch such data? Based from how it works, yes, web scraping is legal as long as it is properly used and cited by the scraper. Tons of users have benefitted from using web scraping in gathering data from all kinds of sources. And it’s not that hard to web scrape a page. All you need to have is a reliable tool and you’re all set to go.
