Difference between XML Schema and XMI

Question

What is the difference between XML Schema (XSD) and XMI?

Answer 1

It's a bit like the difference between a dictionary and a gardening catalogue. In other words, they have very little in common.

XML Schema is a way of describing the structure and constraints on a class of XML documents.

XMI is an XML representation of UML models.

If you don't understand the difference, then you haven't understood one of these specifications, or perhaps you haven't understood either of them.

Answer 2

Sorry for posting in this super-old thread, but I just came around the same problem and found that the accepted answer is super-wrong, which is curious because the author of the accepted answer apparently has not understood anything about XMI or XMI radically changed in the recent past.

XMI 2.5.1 is in fact a standard that describes how to create an XML Schema from a given MOF model and how to implement cross-references between objects as XML only allows hierarchical structures.

Thus, XMI can be applied to any domain, not just software modeling (UML) or business processes (BPMN). However, be careful that XMI is usually applied at the level of a metamodel, not the level of an instance model.