Friday, June 18, 2004

Compatibility in a temporally decoupled distributed world

Carlos comments on the one-sided nature of Liskov's Substitition Principle.
As I've said many times, in a document-centric, message-centric world, objects are not the center of the universe so API substitutability is not a useful metric for compatibility. (Example, in REST, there is only one "API" so substitutability does not arise).

I think Carlos is right when he says we need to look at both the "provider" and "requirer" sides. We need to focus on foreward and backward compatability of message *notations* by means of a message processing model, not API comptability through polymorphism.

RIG 6 in the interoperability guidelines I am working on with the Irish government for the public services broker, addresses this issue.

Dave Orchard is well worth reading on this topic.


Anonymous said...

Thanks for sharing the link, but unfortunately it seems to be offline... Does anybody have a mirror or another source? Please reply to my post if you do!

I would appreciate if a staff member here at could post it.


Anonymous said...


Thanks for sharing this link - but unfortunately it seems to be down? Does anybody here at have a mirror or another source?


Sean McGrath said...

Best to contact for RIG documents.