[flex / django] communications with djangoamf

[Update: DjangoAMF has been patched with these changes. Thanks!]

Immediately after I installed DjangoAMF and began playing around I ran into problems. Nothing was working correctly, even though my setup was exactly as the example in the user manual, and Flex was constantly rewarding me with a Client.Data.UnderFlow exception.

I could get the same Flex 2 application working with a gateway running amfphp (which I installed as a control/reference), so I was pretty sure it wasn’t the Flex side of things.

So I began peeking at the transmitted packets with Charles and comparing it to the structure of the remoting envelope. Soon I noticed something a bit, shall we say, dyslexic…

Hmm.

*checks DjangoAMF Python code*

Dang.

Haven’t run into this issue in years. Looks like I ran into this issue for the first time because I am running/testing on my non-Intel Powerbook thus breaking the network byte ordering for me.

A quick python fix and test of the changes confirmed my suspicions. Here’s the fix:

In amf/amf0.py, replace


def write_long(l, output):
  d = struct.pack('L', l)
  d = d[::-1]
  output.write(d)

def write_int(n, output):
  d = struct.pack('H', n)
  d = d[::-1]
  output.write(d)


with


def write_int(n, output):
  output.write(struct.pack('H', socket.htons(n)))

def write_long(l, output):
  output.write(struct.pack('L', socket.htonl(l)))


I hope this helps any other Mac programmers who might be struggling with getting this to work; getting these two frameworks running together is a real pleasure to behold. Stay tuned.