This exception is used to indicate that a problem occurred attempting to get an entity,
the reference to the failed entity should be returned in the exception along with the
response code which is indicative of the failure (if possible)
HTTP Response Codes (http://en.wikipedia.org/wiki/List_of_HTTP_status_codes) Client Error
400 Bad Request
The request could not be understood by the server due to malformed syntax.
The request requires user authentication. This will cause a SecurityException to be thrown in the direct servlet.
404 Not Found
The requested resource could not be found. Typically indicates the entity as identified cannot be located.
405 Method Not Allowed
The method specified in the Request-Line is not allowed for the resource identified by the Request-URI.
The response MUST include an Allow header containing a list of valid methods for the requested resource.
422 Unprocessable Entity
The server understands the media type of the request entity, but was unable to process the contained instructions.
501 Not Implemented
The prefix indicated is not handled by the entity system
303 See Other
The response to the request can be found under a different URI and SHOULD be retrieved using a GET method on that resource.
This method exists primarily to allow the output of a POST-activated script to redirect the user agent to a selected resource.
The request has succeeded.
The request has been fulfilled and resulted in a new resource being created.
The newly created resource can be referenced by the URI(s) returned in the entity of the response,
with the most specific URI for the resource given by a Location header field.
204 No Content
The server has fulfilled the request but does not need to return an entity-body, and might want to return updated metainformation.