1200

======== BEGIN INBOUND STREAM ========
PUT /articles/123/ HTTP/1.1
Host: example.com
User-Agent: demo
Content-Type: text/plain
Content-Length: 16
If-Match: "85m7uPU2MLiBz"

Hello world!

======== BEGIN OUTBOUND STREAM ========
HTTP/1.1 428 Precondition Required
Date: Thu, 31 Dec 2015 18:26:56 GMT
Content-Type: text/plain
Content-Length: 31

Please include an entity tag.
