What is Selenium?

• Selenium is mainly used for automating the browsers. i.e it automates only the web application.
• Language that selenium supports are :
• JAVA, C#,JavaScript, Objective C,Perl,PHP,Python,Ruby.

Selenium-RC API(Selenium 1.x)-Architecture

Advantages:

• Selenium IDE is very easy to use.
• Programming language experience is not required for Selenium IDE.
• Selenium IDE provides Logging capabilities using file login plug-in.

Disadvantages:

• Selenium RC does not directly communicate with the browser.
• Poor Programming interface.
• Selenium RC doesn't support dynamic finders
• Selenium RC doesn't explicitly provide aids to handle alerts, navigations, dropdowns
• Selenium RC doesn't support listeners

Selenium Webdriver (Selenium 2.0)

Selenium 1.0 + WebDriver = Selenium 2.0

WebDriver overcomes the limitation of Selenium RC's.

Advantages:

• WebDriver communicates directly with the web browsers. Thus making it much faster.
• WebDriver doesn't require any server to be started before executing the test scripts
• WebDriver is a purely object oriented tool
• WebDriver supports dynamic finders
• WebDriver offers a wide range of utilities and classes that helps in handling alerts, navigations, and dropdowns efficiently and effectively.

Limitation:

• WebDriver Cannot Frequently Support New Browsers.
• WebDriver does not support mobile apps automation till 2.x

Selenium WebDriver and Selenium Server

• Selenium Webdriver Api :If your browser and tests will all run on the same machine

• Selenium Webdriver and Selenium Server:

• You are using Selenium-Grid to distribute your tests over multiple machines or virtual machines (VMs).
• You want to connect to a remote machine that has a particular browser version that is not on your current machine.
• You are not using the Java bindings (i.e. Python, C#, or Ruby) and would like to use HtmlUnit Driver
• When you want to use selenium webdriver in Jmeter,SOUP UI ,other test tools etc.

How Selenium WebDriver Automates a Browser

• Selenium basically automates a browser on the basis of DOM elements.
• Basically it identify any element on the basis of DOM.

Locating the UI Elements: