Steve Jones, who I’ve had a steak pie with, is a terrific fellow. (Thought that was a nice opening sentence).

Don’t worry, there’s no “however”. He’s cool. Anyhow he’s posted on his blog about how Metadata isn’t Magic [1].

I like this post a lot, very true. I like the exploration of the boundaries of what makes metadata interesting. Metadata is interesting to the extent that it changes the world. Metadata can change the world in the sense that it can either tell a person something about the data, or it can execute in a runtime context. So BPEL or service contracts are delivered on engines or policy enforcement points during run time. That makes those executable metadata. Metadata which is targeted at informing people about the status of a thing is more descriptive metadata.

So executable metadata *is* pretty much code, sure enough.

Anyhow, BPEL is kind of a lousy example because BPEL certainly requires quite a bit of heavy lifting in order for it to really work. But what about service contracts? I know they are not magic either and require runtime policy enforcement–but they are pretty low hanging fruit for configuration by not-that-technical people. This can increase the diversity and volume of consumption patterns (some call this “reuse”), which is generally considered good.

Of course it’s not magic–but configuration of metadata in the context of contracts produces a lot of business agility. The aspect that also needs to accompany any talk of SOA agility is governance. Just because you *can* toggle metadata doesnt mean you should. And when that metadata is executable, the stakes go up!!!

Miko

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