There are a few things I have been wanting to tie together for the last week or so. Now I guess I am getting around to it. Otherwise another few weeks could fly by.
In no particular order they are:
- Gilad Bracha's ideas on "Service Objects" and their lifecycles.
- Ian Pumierta's (et al.) work on bootstrapping an ideally minimimal, evolvable object system. (video from a Stanford lecture)
- Dan Creswell's thoughts on objects and dependency injection, and concurrent, distributed systems evolution.
- Gilad's talk mentions Erlang.
- Everything about objects gets back to Alan Kay sooner or later. One of my favorite quotes of his...
Smalltalk is object-oriented, but it should have been message oriented.What this means to me is that a system (in the home, in the data center, around the world, whereever) should be able to send messages to each other far more easily than they currently are able. And systems should be far less concerned with what is "on the inside", or that their insides necessarily have anything in common with each other.
Erlang is currently the premier tool for building concurrent systems. And Joe Armstrong is its prophet. Really interesting web servers (yaws and erlyweb), IM servers (ejabberd), mail servers (experimental and commercial), voice servers, data bases, and enterprise message servers exist in Erlang. And a ton of other things. Aside: recently Erlang started taking advantage of multicore and SMP hardware in addition to distributed hardware.
I appreciate the important ideas and work that Gilad, Ian, and others are doing. At the end of the day though that work strikes me as improvements on the current mediocre state of the intraprocess runtimes. The Smalltalk folks have already shown the runtime can be far simpler, stable, and evolvable than the ones most of us use most of the time. (PDF on the Silt server in Smalltalk.) Gilad and Ian's work may ultimately improve on that.
Does your app leave little "pid" files around to indicate something is running with some OS process id? Or can your app actually start up and detect that some other process in the system is running? And begin communicating with it?
Can those various processes come and go, and yet the system continues to run, perhaps after healing itself?
That is *service* oriented and that seems to be more about messages and not so much about objects. We should have a "programmer's holiday" where we all pause our current work and play with Erlang for a week. Not that we should all be using Erlang for everything, but we should all be *influenced* by Erlang for everything.
