Specify supported media types when sending “415 unsupported media type”

Question

If a clients sends data in an unsupported media type to a HTTP server, the server answers with status \"415 unsupported media type\". But how to tell the client what media t

Answer 1

There is no specification at all for what to do in this case, so expect implementations to be all over the place. (What would be sensible would be if the server's response included something like an Accept: header since that has pretty much the right semantics, if currently in the wrong direction.)

Answer 2

I believe you can do this with the OPTIONS Http verb.

Also the status code of 300 Multiple Choices could be used if your scenario fits a certain use case. If they send a request with an Accept header of application/xml and you only support text/plain and that representation lives at a distinct URL then you can respond with a 300 and in the Location header the URL of that representation. I realize this might not exactly fit your question, but it's another possible option.

And from the HTTP Spec:

10.4.7 406 Not Acceptable

The resource identified by the request is only capable of generating response entities which have content characteristics not acceptable according to the accept headers sent in the request.

Unless it was a HEAD request, the response SHOULD include an entity containing a list of available entity characteristics and location(s) from which the user or user agent can choose the one most appropriate. The entity format is specified by the media type given in the Content-Type header field. Depending upon the format and the capabilities of the user agent, selection of the most appropriate choice MAY be performed automatically. However, this specification does not define any standard for such automatic selection.

      Note: HTTP/1.1 servers are allowed to return responses which are
      not acceptable according to the accept headers sent in the
      request. In some cases, this may even be preferable to sending a
      406 response. User agents are encouraged to inspect the headers of
      an incoming response to determine if it is acceptable.

Answer 3

tl;dr; Edited the generated proxy class to inherit from Microsoft.Web.Services3.WebServicesClientProtocol**.

I came across this question when troubleshooting this error, so I thought I would help the next person who might come through here, although not sure if it answers the question as stated. I ran into this error when at some point I had to take over an existing solution which was utilizing WSE and MTOM encoding. It was a windows client calling a web service.

To the point, the client was calling the web service where it would throw that error. Something that contributed to resolving that error for me was to check the web service proxy class that apparently is generated by default to inherit from System.Web.Services.Protocols.SoapHttpClientProtocol. Essentially that meant that it didn't actually use WSE3.

Anyhow I manually edited the proxy and changed it to inherit from Microsoft.Web.Services3.WebServicesClientProtocol.

BTW, to see the generated proxy class in VS click on the web reference and then click the 'Show All Files' toolbar button. The reference.cs is da place of joy!

Hope it helps.

Answer 4

In his book "HTTP Developer's Handbook" on page 81 Chris Shiflett explains what a 415 means, and then he says, "The media type used in the content of the HTTP response should be indicated in the Content-Type entity header."

1) So is Content-Type a possible answer? It would presumably be a comma-separated list of accepted content types. The obvious problem with this possibility is that Content-Type is an entity header not a response header.

2) Or is this a typo in the book? Did he really mean to say "the HTTP request"?