ETag and Last-Modified values not appearing in response.[Answered] RSS

• • Reply
  awebb

  Member

  81 Points

  90 Posts

  ETag and Last-Modified values not appearing in response.

  Feb 28, 2012 11:34 AM|awebb|LINK

  I have migrated my code from WCF Web API preview 6 to ASP.NET Web API.  There's one remaining issue: setting ETag and Last-Modified response headers in my controller actions doesn't result in these headers appearing in the response received by the client.  It worked fine in WCF.

  E.g. I do this in an action:-

  if (result.LastModified != null)
    response.Content.Headers.LastModified = result.LastModified.Value.ToUniversalTime();
  
  if (result.SequenceNumber != null)
    response.Headers.ETag = new EntityTagHeaderValue
                                    ("\"" + result.SequenceNumber.Value.ToString(CultureInfo.InvariantCulture) + "\"", false);

  When these two statements are executed, no such headers appear in the response.  E.g. Fiddler gets this:-

  HTTP/1.1 200 OK
  Server: ASP.NET Development Server/10.0.0.0
  Date: Tue, 28 Feb 2012 16:23:48 GMT
  X-AspNet-Version: 4.0.30319
  Cache-Control: no-cache
  Pragma: no-cache
  Expires: -1
  Content-Type: application/vnd.statpro.revolution.wapi.portfolios+json; charset=utf-8
  Connection: Close
  Content-Length: 5909

  Attempting to set other headers does work.  E.g. I set the Location header to some random URI (http://www.google.com), and Fiddler did receive the Location header set to that value.

  Bug?  Or am I missing something?

  Andrew
• • Reply
  Kiran Challa

  Participant

  781 Points

  301 Posts

  Microsoft

  Re: ETag and Last-Modified values not appearing in response.

  Feb 28, 2012 12:13 PM|Kiran Challa|LINK

  I have tried the following and setting these headers works....

  HTTP/1.1 200 OK
  Cache-Control: no-cache
  Pragma: no-cache
  Content-Type: text/plain; charset=utf-8
  Expires: -1
  Last-Modified: Tue, 28 Feb 2012 17:05:51 GMT
  ETag: "686897696a7c876b7e"
  Server: Microsoft-IIS/7.0
  X-AspNet-Version: 4.0.30319
  X-Powered-By: ASP.NET
  Date: Tue, 28 Feb 2012 17:05:51 GMT
  Content-Length: 5

  hello

  [HttpGet]
          public HttpResponseMessage GetString()
          {
              HttpResponseMessage response = new HttpResponseMessage();
              response.Headers.ETag = new EntityTagHeaderValue("\"686897696a7c876b7e\"");
              response.Content = new StringContent("hello");
              response.Content.Headers.LastModified = DateTime.Now.ToUniversalTime();
  
              return response;
          }

  Thanks,
  Kiran Challa
• • Reply
  davebettin

  Member

  131 Points

  93 Posts

  Re: ETag and Last-Modified values not appearing in response.

  Feb 28, 2012 12:18 PM|davebettin|LINK

  Howdy,

  It looks like this an issue with Cassini. Headers are set properly in IIS and IIS Express but not in Cassini. I would switch your API over to use IIS Express and it should work without any issues.

  Cheers,

  Dave

  Dave Bettin
  @dbettin
• • Reply
  awebb

  Member

  81 Points

  90 Posts

  Re: ETag and Last-Modified values not appearing in response.

  Feb 29, 2012 05:01 AM|awebb|LINK

  davebettin

  It looks like this an issue with Cassini.

  Thanks Dave.  Yes, it's Cassini.  Or rather the combination of ASP.NET Web API and Cassini, because this was working in WCF.

  No matter... I will use IIS Express from now on.

  Andrew
• • Reply
  Vistor

  None

  0 Points

  9 Posts

  Re: ETag and Last-Modified values not appearing in response.

  Mar 17, 2012 03:07 PM|Vistor|LINK

  Cassini ignores ETag and Last-Modified headers if Cache-Control is 'private', which it is by default. Changing Cache-Control to 'public' causes both ETag and Last-Modified appear on the client correctly.

  -Vitaly