Salesforce.com has a web service based API. It allows customers to very
thoroughly customize the application, adding new columns to tables, and even
adding new tables and relations between tables. Naturally, the WSDL changes
to reflect this.

They have an area on their web site where you can download your own,
customer-specific WSDL, up to date with whatever changes you've made. You
could do the same, or have a web service operation which returns the current
WSDL.

As to enumerated values, they're ok (once you deal with a dynamic WSDL). Be
aware, though that XML Schema doesn't do enumertions like a programming
language does. One can enumerate the acceptable values for a particular
attribute or element, but that is only a constraint on the lexical space.
The enumerated values don't have integers associated with them.

John