Article:		How to Create a REST Protocol
Subject:		PUT is not an update
Date:		2004-12-03 04:58:54
From:		jgregorio
Response to: PUT is not an update
To quote from RFC 2616: On POST[1]: " Extending a database through an append operation." On PUT[2]: " The PUT method requests that the enclosed entity be stored under the supplied Request-URI. If the Request-URI refers to an already existing resource, the enclosed entity SHOULD be considered as a modified version of the one residing on the origin server." [1] http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html#sec9.5 [2] http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html#sec9.6

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• PUT is not an update
  2004-12-06 08:18:12 jdodds [Reply]
  
  HTTP was originally created for managing collections of documents.

  
  PUT is intended to be used for adding new documents. A PUT only becomes an 'update' when the specified document already exists. PUT can effectively be both CREATE and UPDATE.

  
  POST is really much more general than either a CRUD CREATE or a PUT. (Joe, I think you did yourself a disservice with the quote that you pulled from section 9.5 of the HTTP spec.)

  
  There is, however, a more subtle point that isn't explicit in the article. From section 9.6:

  
  "The fundamental difference between the POST and PUT requests is reflected in the different meaning of the Request-URI. The URI in a POST request identifies the resource that will handle the enclosed entity. That resource might be a data-accepting process, a gateway to some other protocol, or a separate entity that accepts annotations. In contrast, the URI in a PUT request identifies the entity enclosed with the request -- the user agent knows what URI is intended and the server MUST NOT attempt to apply the request to some other resource."

  
  While I tend to disagree with the CRUD table in the article, I don't have the same issue with the final table which shows the protocol and reflects that a POST as CREATE is performed against the 'All Employees' collection and the PUT as UPDATE is performed against a specific 'employee'.

  
  I do have one question: What does it mean to POST to an employee?