MSN Messenger and AIM instant messenger war: reverse engineering and sabotage

Found this amazing Microsoft story from Twitter told first-hand by David Auerbach, a former Microsoft developer in 1998 on the MSN Messenger Service team. It’s a sleuthing story of back-and-forth reverse engineering by Microsoft and sabotage by AOL, all for one simple feature – chatting with AOL Instant Messenger friends inside MSN Messenger.

It’s a bit long but a great weekend read.

After we finished the user part of the program, we had some down- time while waiting for the server team to finish the Hotmail integration. We fixed every bug we could find, and then I added another little feature just for fun. One of the problems Microsoft foresaw was getting new users to join Messenger when so many people already used the other chat programs. The trouble was that the programs, then as now, didn’t talk to one another; AOL didn’t talk to Yahoo, which didn’t talk to ICQ, and none of them, of course, would talk to Messenger. AOL had the largest user base, so we discussed the possibility of adding code to allow Messenger to log in to two servers simultaneously, Microsoft’s and AOL’s, so that you could see your Messenger and AIM buddies on a single list and talk to AIM buddies via Messenger. We called it “interop.”

…

Our client took the surrounding boilerplate and packaged up text messages in it, then sent it to the AOL servers. Did AOL notice that there were some odd messages heading their way from Redmond? Probably not. They had a hundred million users, and after all I was using their own protocol. I didn’t even send that many messages. My program manager and I thought this little stunt would be deemed too dubious by management and taken out of the product before it shipped. But management liked the feature. On July 22, 1999, Microsoft entered the chat markets with MSN Messenger Service. Our AOL “interop” was in it.

…

So I took the AIM client and checked for differences in what it was sending, then changed our client to mimic it once again. They’d switch it up again; they knew their client, and they knew what it was coded to do and what obscure messages it would respond to in what ways. Every day it’d be something new. At one point they threw in a new protocol wrinkle but cleverly excepted users logging on from Microsoft headquarters, so that while all other Messenger users were getting an error message, we were sitting at Microsoft and not getting it. After an hour or two of scratching our heads, we figured it out.

…

The messenger war was a rush. Coming in each morning to see whether the client still worked with AOL was thrilling. I’d look through reams of protocol messages to figure out what had changed, fix the client, and try to get an update out the same day. I felt that I was in an Olympic showdown with some unnamed developers over at AOL. I had no idea who my adversaries were, but I had been challenged and I wanted to win.

Image credit: Robert Ian Hawdon