What is Selenium WebDriver

Selenium 

1. Selenium is an automation testing tool used to automate various types of Web applications. It consists of three main parts Selenium IDE, Selenium RC & Selenium WebDriver. 

Difference between Selenium IDE and Rc And WebDriver.

Selenium IDE

1. The Selenium IDE is basically something having record & playback options which present in the every automation tool like QTP, Sliktest etc. & also has very good user interface. 
2. The main limitation of Selenium IDE is that, it supported in only Firefox browser. 
3. If you want to execute your scripts on different browsers, then you can use Selenium RC (Selenium Remote Control).
4.   It does not support to test iphone/Android application.

          Selenium Rc 

1. The Selenium RC supports multiple browsers like IE, Firefox, Chrome, Safari, Opera etc.
2. It is standalone java program which allow you to run Html test suites.
3. It also supports multiple languages like Java, Ruby, C#, Perl, Python etc. 
4. You have to get expertise in one language (preferred Java language) & code in selenium RC.

You first need to launch a separate application called Selenium Remote Control (RC) Server before you can start testing

Selenium Rc Architecture

1. The Selenium RC Server acts as a "middleman" between your Selenium commands and your browser
2. When you begin testing, Selenium RC Server "injects" a Javascript program called Selenium Core into the browser.
3. Once injected, Selenium Core will start receiving instructions relayed by the RC Server from your test program.
4. When the instructions are received, Selenium Core will execute them as Javascript commands.
5. The browser will obey the instructions of Selenium Core, and will relay its response to the RC Server.
6. The RC Server will receive the response of the browser and then display the results to you.
7. RC Server will fetch the next instruction from your test script to repeat the whole cycle.

 

Selenium WebDriver

Selenium Webdriver makes direct calls to the browser using each browser’s native support for automation.

1. Browser Support

Google Chrome 12+

Internet Explorer 6, 7, 8, 9

Firefox 3+

Opera 11.5+

HtmlUnit 2.9

Android – 2.3+

iOS 3.2+

Safari 5.1+     

Language bindings

Java

C#

Ruby

Python

Javascript (Node)

Perl

PHP

Haskell

Objective-C

Selenium WebDriver do not require selenium server for running test.
WebDriver is using native automation from each and every supported language for running automation scripts on browsers.
WebDriver supports web as well mobile application testing so you can test mobile applications (iPhone or Android).
Supporting latest versions of almost all browsers.
WebDriver controls the browser itself.
Selenium Disadvantages

1. It does not support and non web-based applications, it only supports web based applications.
2. Its and open source tool so in case of any technical issues you need to rely on the selenium community forums to get your issue resolved.
3. You need to know at least one of the supported language very well in order to automate your application successfully.
4. No inbuilt reporting capability so you need plugins like JUnit and TestNG for test reports.

5. Lot of challenges with IE browser.

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