Go Web Scraping Quick Start Guide

By : Smith

3.5 (2)

Buy this Book

Go Web Scraping Quick Start Guide

3.5 (2)

By: Smith

Buy this Book

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.

Preface

Who this book is for

What this book covers

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Free Chapter

Introducing Web Scraping and Go

What is web scraping?

Why do you need a web scraper?

What is Go?

Why is Go a good fit for web scraping?

How to set up a Go development environment

Summary

The Request/Response Cycle

What do HTTP requests look like?

What do HTTP responses look like?

What are HTTP status codes?

What do HTTP requests/responses look like in Go?

Summary

Web Scraping Etiquette

What is a robots.txt file?

What is a User-Agent string?

How to throttle your scraper

How to use caching

Summary

Parsing HTML

What is the HTML format?

Searching using the strings package

Searching using the regexp package

Searching using XPath queries

Searching using Cascading Style Sheets selectors

Summary

Web Scraping Navigation

Following links

Submitting forms

Avoiding loops

Breadth-first versus depth-first crawling

Navigating with JavaScript

Summary

Protecting Your Web Scraper

Virtual private servers

Proxies

Virtual private networks

Boundaries

Summary

Scraping with Concurrency

What is concurrency

Concurrency pitfalls

The Go concurrency model

sync package helpers

Summary

Scraping at 100x

Components of a web scraping system

Scraping HTML pages with colly

Scraping JavaScript pages with chrome-protocol

Distributed scraping with dataflowkit

Summary

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Scraping JavaScript pages with chrome-protocol

In Chapter 5, Web Scraping Navigation, we looked at navigating websites that require JavaScript using selenium and the WebDriver protocol. There is another protocol that has been developed recently that offers many more features you can take advantage of to drive a web browser. The Chrome DevTools Protocol was started for use on Chrome browsers, but it has been adopted by the W3C's Web Platform Incubator Community Group as a project. The major web browsers work together to develop a standard protocol called the DevTools Protocol to adopt for all of their browsers.

The DevTools Protocol allows external programs to connect to a web browser and send commands to run JavaScript, and collect information from the browser. Most importantly, the protocol allows the program to collect the HTML on demand. This way, if you were scraping...