To: The editor at Computer magazine (computer.org)
CC: Ken Birman at Cornell University

I enjoyed reading the October 2005 edition of Computer, and after the obligatory reading of “At Random”, I flipped with interest to the Web Technologies column: “Can Web Services Scale Up?” by Ken Birman.

In my simple take on it, Ken suggests the architectural solution to scaling Web services is in relying on the infrastructure (i.e. application servers) to sort it out, while the “user simply designs a data structure and employs multicast technology” for the magical but expensive fairies to sprinkle data dust everywhere. Of course, he points out, CORBA tried and failed, erring by embedding a powerful solution into a tool mismatched to developer needs. CORBA’s lack of wide adoption is due to arguably far more errors that just that (but that’s another topic). He then also sets the scene for even more infrastructure with the requirement for sophisticated monitoring and management tools for these behemoth clusters of RAPS of RACS.

I couldn’t find where Ken addresses the reason for why such complex clustering technologies would be “needed” for scale in the first place: stateful context in the middle tier. Get rid of that and you get rid of the need for sophisticated infrastructure, too-smart-for-their-packets network devices, and super-uber-monitoring-management-of-management-monitors that monitor and manage clusters of hosts of virtual machines. And then you can also buy this neat tool from Quest to tell you why all that stuff has broken too.

State lives in the data tier. Those boys know how to manage and scale state real well. Let’s keep it there, rather than multicasting megabytes of it in the app tier to handle failover (because that’s naught to do with load in a real man’s architecture).

Web services scale horizontally very well when they are provided their context by their consumers (and perhaps handlers along the way), their state is persisted in the nether tiers of database land, and have their load balanced by simple little devices in the switch fabric. They’re a lot cheaper like that too. It’s sort of like the difference between the Library of Congress and the World Wide Web. Are we getting it yet?

Regards,
Josh