Uploading a file to Google Docs Api getting error 504

Question

I'm working on a delphi api for Google docs and having a hard time getting the upload to work. I'm following Google's development guide here and from what I understand it looks like the process should go like this:

1. Make a POST request to this url: https://docs.google.com/feeds/upload/create-session/default/private/full/?access_token=my_access_token&v=3&convert=false with these headers: X-Upload-Content-Type and X-Upload-Content-Length
2. Get a 200 OK response with the next upload location stored in the Location header
3. Make a PUT request to the Location header with the header Content-Type set to whatever I had X-Upload-Content-Type set to in step 1 and the header Content-Range set to something like this: bytes 0-524287/2097152 and the first 512kb of data in the body
4. Get a 308 Resume Incomplete Response that has the next upload location in the Location header
5. Go back to 3 until all bytes are uploaded, at which point I will receive a 201 Created response that will have the xml data describing the file I uploaded

Everything up to and including step 3 works fine. It is at step 4 that things start to go wrong.

The one thing that confuses me the most is that the response on step 4 doesn't contain a Location header. I figured that meant I should just send the next request to the same url, but that causes me to get a 504 error. I tried the entire process with fiddler just to see if it was the delphi code, a lack of understanding on my part, or something that google is doing.

Here's the requests and responses I sent and received using fiddler:

POST https://docs.google.com/feeds/upload/create-session/default/private/full/?access_token=my_access_token&v=3&convert=false HTTP/1.1
Content-Type: application/x-www-form-urlencoded
X-Upload-Content-Type: application/octet-stream
X-Upload-Content-Length: 2097152
Content-Length: 0
Host: docs.google.com

HTTP/1.1 200 OK
Server: HTTP Upload Server Built on May 16 2012 12:03:24 (1337195004)
Location: https://docs.google.com/feeds/upload/create-session/default/private/full/?access_token=my_access_token&v=3&convert=false&upload_id=AEnB2Ur9-9VxMSI6kaFzbybY2qiyzK6kVoKzcZ6Yo02H8Ni4FlQFl_N06DdjZXzp3vSjOPH3CEb_4vDlKZp7VlC0hxpkypzlKg
Date: Tue, 22 May 2012 16:53:27 GMT
Pragma: no-cache
Expires: Fri, 01 Jan 1990 00:00:00 GMT
Cache-Control: no-cache, no-store, must-revalidate
Content-Length: 0
Content-Type: text/html

PUT https://docs.google.com/feeds/upload/create-session/default/private/full/?access_token=my_access_token&v=3&convert=false&upload_id=AEnB2Ur9-9VxMSI6kaFzbybY2qiyzK6kVoKzcZ6Yo02H8Ni4FlQFl_N06DdjZXzp3vSjOPH3CEb_4vDlKZp7VlC0hxpkypzlKg HTTP/1.1
Content-Type: application/octet-stream
Content-Length: 524288
Content-Range: bytes 0-524287/2097152
Host: docs.google.com
[first 512kb of data here]

HTTP/1.1 308 Resume Incomplete
Server: HTTP Upload Server Built on May 16 2012 12:03:24 (1337195004)
Range: bytes=0-524287
X-Range-MD5: bd9d4ee7afa24b7da0e685f05b5f1f44
Date: Tue, 22 May 2012 16:54:29 GMT
Pragma: no-cache
Expires: Fri, 01 Jan 1990 00:00:00 GMT
Cache-Control: no-cache, no-store, must-revalidate
Content-Length: 0
Content-Type: text/html

PUT https://docs.google.com/feeds/upload/create-session/default/private/full/?access_token=my_access_token&v=3&convert=false&upload_id=AEnB2Ur9-9VxMSI6kaFzbybY2qiyzK6kVoKzcZ6Yo02H8Ni4FlQFl_N06DdjZXzp3vSjOPH3CEb_4vDlKZp7VlC0hxpkypzlKg HTTP/1.1
Content-Type: application/octet-stream
Content-Length: 524288
Content-Range: bytes 524288-1048575/2097152
Host: docs.google.com
[next 512kb of data]

HTTP/1.1 504 Fiddler - Send Failure
Content-Type: text/html; charset=UTF-8
Connection: close
Timestamp: 10:54:14.056

The only thing I was able to do was to be able to say for a fact that it is not just the delphi code that is wrong, and since I don't think it's google, I'm going to have to go with I don't understand something that should be happening. What am I missing?

Edit

I was able to get the upload working, I'm not entirely sure what I did differently, but the documentation is a little misleading. At least it is to me. When you send a PUT request, you don't get a new location, you just continue to upload to the same one. Also, when you finish the upload, the 201 response doesn't contain the actual XML data, instead, it has a Location header that points to where you can grab the XML data from. Not a huge deal but a little confusing.

Answer 1

It seems like the 504 error is returned by Fiddler, these two links should help:

https://urda.com/blog/2010/09/28/iis-services-504s-and-fiddler/

https://urda.com/blog/2010/09/30/follow-up-iis-services-504s-and-fiddler/