The New Application Architecture

Phil Windley looks at new hardware architectures and their forces on future software systems...

Application servers (like jBoss or Weblogic) support a development model in which programmers develop threadless code and the app server manages the threads. That simplifies the point too much, perhaps, but I think having that much parallel processing power on a single chip might make app servers much more important for developing applications. There are continuing debates about whether app servers add more complexity than their worth, but that might be because we haven't met many problems large enough to require them–yet. In the early 60's programmers scoffed at the idea of operating systems as being "needlessly complex;" that idea is ludicrous today.

I think application servers are the new operating system. (Ten years ago they were the new transaction monitor, but now we know we all need one. We all need more than one.) We need to be able to write smaller "applications" and have them interact more easily. Look at the advice for programming web applications, web services, EJB's, as well as applications in Erlang. They are all very similar. Erlang applications tend to be more simple than the rest because the available framework takes this point to the extreme.

Those other systems are built by and large on heavy-weight process technology. Maybe Erlang is the new Lisp. We need a Lisp for lighter-weight process interaction, as Jon Udell pointed out.

I should point out that I equate "web server" and "app server". That there is a distinction is an artifact rather than an inherent reason. An application server is inherently a "process monitor" with various drivers. HTTP drivers, SMTP drivers, XMPP drivers, etc. I don't think the new "superplatform" belongs to Microsoft, IBM, or BEA. The superplatform is one based on the standard application protocols. The best of these platforms will combine support for these application protocols (and more... IMAP? WebDAV?) and abstract the complexity. Most of us should be writing sequential code, rule-based code, constraint-based declarative code, etc. But we'll have to plug into these protocols.

Phil continues...

It's tough to see how you'll use that much parallelism on the desktop. I just counted the number of processes running on my Powerbook: 76... there are things we've hardly been able to imagine.

This is the result of the languages we have been using to think with. As Phil points out, these new hardware architectures will give us more reasons to think differently.