Selenium

Selenium is an open source functional testing tool for web applications. It was created by Jason Huggins, earlier it was known as JavaScriptTestRunner and is used to test an internal time and expense application.

Later, it was released to the open source community as Selenium. It was named as Selenium because it overcame the shortcomings of another competitor.

 Selenium is popular because:

• It supports multiple programming languages.
• It supports automation of multiple browsers.
• It supports multiple operating systems.
• It is available free of cost.

Components of Selenium

• Selenium IDE: It is a tool used for recording and playing back scripts.
• Selenium RC: It is a combination of a Selenium server and a client, which allowed automation of any browser on any operating system.
• Selenium WebDriver: It uses the technology of WebDriver API, where every browser has the capability through its API to automate itself.  It is the main component of Selenium.
• Selenium Grid: It uses server component from the Selenium RC and executes it in two different modes as hub and node.

Architecture of Selenium

Selenium has four main components:

1. The client libraries (available in different programming languages)
2. JSON wire protocol over HTTP for communication to send commands from client to server
3. WebDriver for every browser
4. Browsers (Chrome, Firefox, IE, Opera)

How it works

Client libraries are available in different programming languages. Scripts are created by using client libraries and then the commands are send to the WebDriver server by using the JSON wire protocol over HTTP. The WebDriver then, for each individual browser receives these commands and automates the browser and performs action on them, this will lead to achieve the task.