Book Image

Go Web Scraping Quick Start Guide

By : Vincent Smith
Book Image

Go Web Scraping Quick Start Guide

By: Vincent Smith

Overview of this book

Web scraping is the process of extracting information from the web using various tools that perform scraping and crawling. Go is emerging as the language of choice for scraping using a variety of libraries. This book will quickly explain to you, how to scrape data data from various websites using Go libraries such as Colly and Goquery. The book starts with an introduction to the use cases of building a web scraper and the main features of the Go programming language, along with setting up a Go environment. It then moves on to HTTP requests and responses and talks about how Go handles them. You will also learn about a number of basic web scraping etiquettes. You will be taught how to navigate through a website, using a breadth-first and then a depth-first search, as well as find and follow links. You will get to know about the ways to track history in order to avoid loops and to protect your web scraper using proxies. Finally the book will cover the Go concurrency model, and how to run scrapers in parallel, along with large-scale distributed web scraping.
Table of Contents (10 chapters)

Breadth-first versus depth-first crawling

Now that you have the ability to navigate to different pages, as well as the ability to avoid getting stuck in a loop, you have one more important choice to make when crawling a website. In general, there are two main approaches to covering all pages by following links: breadth-first, and depth-first. Imagine that you are scraping a single web page that contains 20 links. Naturally, you would follow the first link on the page. On the second page, there are ten more links. Herein lies your decision: follow the first link on the second page, or go back to the second link on the first page.

Depth-first

If you choose to follow the first link on the second page, this would be considered...