How to script a web crawler
If you’ve ever wanted to collect and extract valuable data from the web, writing a web crawler might be the best way to do it. Crawlers are data scrapers that can find, crawl, and navigate websites to capture, scrape, extract, and store the information you need.
These are programs developed to read data from the Internet by locating and downloading the targeted web pages. For this reason, you can use them for various applications, such as finding competitor prices on e-commerce sites, collecting user reviews and comments on social networks, sports scores, stocks, financial information , etc
Even though it is much easier to script a web crawler today thanks to top programming languages with massive libraries, it still requires some know-how. Let’s talk about what a web crawler is and how to set up a crawler to create a database you can rely on.
Basics of web crawlers
What is an indexing robot?
Simply put, it is a program, an Internet crawler that crawls and indexes data (content) of web pages on the web. Also called a crawler, spider, or bot, a crawler uses the power of automation to target, crawl, and extract data and information from web pages. It also exports the extracted data into a series of structured formats, such as database, table, list, etc.
The most popular internet crawler known to all internet users is Google. It’s a search engine which uses its crawlers to constantly search the web for the latest and most up-to-date content.
Without its crawlers, Internet users would not be able to receive search results within seconds each time they request to see content online. Billions of Internet users generate quintillions of bytes of data every day. Imagine going through all that data and not being able to automatically find what you’re looking for. Oxylabs has a blog that goes more in depth on the topic “what is a web crawler”, you should definitely check.
Crawler Scripts Explained
Since it’s impossible to make sense of the internet without crawling the web, a search engine is needed to quickly crawl the web, find and index the most relevant websites, and deliver you a webpage you asked to see. You can create a web crawler to help you achieve all of these goals and more.
In the digital business landscape, modern businesses use web crawlers for a variety of purposes, including:
- Data aggregation– businesses need the most up-to-date data to power their operations, beat their competitors, and find the best ways to increase sales. Web crawlers allow them to compile data on various topics from an array of online resources and store it in an easily accessible and secure location.
- Sentiment analysis– knowing what the target audience thinks of particular products and services can help a company improve its marketing and advertising campaigns. Collecting feedback is also a great way to improve your trading strategy. A web crawler can collect valuable information regarding comments and reviews for analysis.
- Lead generation– finding as many leads as possible is the only way to stay relevant in the digital business landscape. Web crawlers can gather all the information a business needs to generate more leads. They can retrieve contact information from attendee lists, public profiles, phone numbers, emails, and more.
The crawler scripting process allows users to determine what they want a crawler to do. Aside from the three use cases we mentioned here; you can also use bots for many other applications.
The process of creating a web crawler
Let’s see what it takes to create a web crawler.
Get ahead of the coding to write your mining script
Learning a programming language or two is a great way to build a scraper that will do everything you want it to do. Python is one of the most popular computer languages for writing bot code.
Python is mainly used for web scraping. It can send HTTP requests to multiple web pages and return the content of targeted web pages. It also allows for better control and page navigation to get the data.
Use web scraping tools
If coding is not an option, you can use web scraping tools to create a web crawler, such as Octoparse. A web scraping tool allows you to create a crawler that can extract the specific type of data you are looking for. Just run the program and locate the main menu.
Select Advanced Mode and enter the target URL to start the explore operation. Configure paging to help your bot discover target web pages by clicking the Next Page button and opening the Tips panel. Select the “Loop click single element” button, then select an element and click it.
Go to the Action Tips panel and select “Loop click each item” to allow your crawler to select all items that contain similar items. Select “Extract text from selected item” and repeat as many times as needed until you get the information you need. When done, click Start Extraction.
Writing a script for a web crawler can seem like a tedious and time-consuming process. However, you have a wide range of tools and means that you can use to get the job done almost without maintenance or any other cost.
Just keep in mind that your crawler will need constant updates to keep up with the constantly changing nature of web pages on the internet. Each website is unique and requires you to write a particular script that will be compatible with the language of the site. It takes a bit of time to get into the science behind it, but it’s totally manageable.