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.

3 comments:

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 seanmcgrath.blogspot.com could post it.

Thanks,
Thomas

Anonymous said...

Hello,

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


Thanks,
William

Sean said...

Best to contact support@reachservices.ie for RIG documents.

Sean