Answer 51: Selenium RC is an offering from SeleniumHQ which tries to overcome following draw backs of Selenium IDE –

• Able to execute tests only with Firefox
• Not able to use full-fledged programming language and being limited to Selenese

Answer 52: Selenium RC has two primary components – 

• Client libraries which let you writes tests in language of your preference i.e. java, C#, perl, php etc.
• Selenium sever which acts as a proxy between browser and application under test (AUT)

Answer 53: Selenium uses java script to drives tests on a browser; Selenium injects its own JS to the response which is returned from AUT. But there is a java script security restriction (same origin policy) which lets you modify html of page using JS only, if JS also originates from the same domain as html. This security restriction is of utmost important but spoils the working of Selenium. This is where Selenium server comes to play an important role.

Selenium server stands between AUT and browser and injects selenium JS to the response received from AUT and then it is delivered to browser. Hence browser believes that entire response was delivered from AUT.

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