What about versioning the API? This is surprisingly hard to get right, but (for many, just as surprisingly) awfully important -- I have seen numerous enterprisey distributed system efforts fail for just (and entirely) this reason. There is no mention in any of the three APIs being talked about here (GoGrid, EH, or Sun) of versioning that I can find? Nor do I recal it being discussed as a first class design goal on this list yet? On the wiki there is no mention of it in the API Design section. Although I confess that I have never used it in anger, there is a fascinating proposal for attacking versioning in a RESTful way here: http://barelyenough.org/blog/2008/05/versioning-rest-web-services/ (with some caveats here: http://barelyenough.org/blog/2008/05/versioning-rest-web-services-tricks-and... ). The REST gurus in this group may well know an even better way to solve the problem. I'd be interested in hearing others' views on this. Mark Masterson Enterprise architect, troublemaker CSC Financial Services EMEA | m: +49.172.6163412 | Internal blog: Schloss Masterson | Public blog: Process Perfection (http://jroller.com/MasterMark/) | mmasterson@csc.com | www.csc.com. CSC • This is a PRIVATE message. If you are not the intended recipient, please delete without copying and kindly advise us by e-mail of the mistake in delivery. NOTE: Regardless of content, this e-mail shall not operate to bind CSC to any order or other contract unless pursuant to explicit written agreement or government initiative expressly permitting the use of e-mail for such purpose ï CSC Computer Sciences Limited • Registered Office: Royal Pavilion, Wellesley Road, Aldershot, Hampshire, GU11 1PZ, UK • Registered in England No: 0963578