According to HTTP 1.1 spec GET, HEAD, and PUT are indempotent and POST is not indempotent. Indempotent mean it doesn't do any updation or transaction at the server.
doTrace is used to get the request messages and used basically for troubleshooting
posted 10 years ago
Methods can also have the property of "idempotence" in that (aside from error or expiration issues) the side-effects of N > 0 identical requests is the same as for a single request. The methods GET, HEAD, PUT and DELETE share this property. Also, the methods OPTIONS and TRACE SHOULD NOT have side effects, and so are inherently idempotent.