Explain idempotent and non-idempotent.

Idempotent means the same request can be made more than once without causing negative consequences on the Server.

In Non-Idempotent Scenario the data submitted in the body of the POST might be destined for a transaction that can’t be reversed. Hence care has to be taken in the application logic.

IDEMPOTENT ==> GET, HEAD, PUT, DELETE, OPTIONS, TRACE

NON-IDEMPOTENT ==> POST

CONNECT
Specification reserves the method name CONNECT for use with a proxy that can dynamically switch to being a tunnel (e.g. SSL tunneling

Http Spec 1.1