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�idempotent?

 
Carlos A. Perez
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Hi every one, im studing for SCWCD and found this question in a mock exam:

�Witch HTTP methods are NOT considered idempotent? but i dont understand what do they mean by "idempotent" in the context of web applications.

Also i would like to know what the doTrace method is for? an if its possible an example. I have read that its for to ask for a loopback but that doesnt give me an idea of how to write one.

Thanks
 
Adeel Ansari
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An idempotent method is a method that if run multiple times has no affect on the state. Its a query method not an update.
 
Adeel Ansari
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You might also like to refer this thread discussing doTrace().
 
Rohit Sajan
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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
 
Flom Xanther
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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.

HTTP/1.1: Method Definitions

Greetings,
Flom
 
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