So, you've been hearing about XMI and would like to base your company's metadata practice on open standards. But the entrance price of the major MOF-compliant repositories is too steep? And you have access to a talented Java software engineer? Read on...
I've been tracking the Sun Netbeans MDR effort for some time now, and have goofed around with it at home. I've been a little critical however at its lack of a real, DBMS-based persistence architecture; previously, the best it had was a B-tree flat file. This has now changed with the submission of a JDBC-based persistence architecture, contributed by John V. Sichi. John, this is truly an excellent service to the open source community and those supporting the OMG's standards vision!
Again, here's the business case: A free repository, if you have some spare software engineering talent.
With the persistence layer front-ended by the MOF-compliant API (the Java Metadata Interface) you can instantiate and interact with any arbitrary MOF-compliant metamodel and its data (e.g. the OMG Common Warehouse Metamodel and models stored in it). In fact, it could be used for a sort of UML-based persistence for regular data instances; I'm very intrigued with the possibility that we have a nascent object/relational mapping architecture based on formal UML emerging here.
If you've instantiated the appropriate metamodel, you can import its XMI. For example, if you instantiate CWM, you can in theory bring in CWM metadata from any data modeling tool that supports it (e.g. Embarcadero). You could then build a Java servlet to access the MDR API for querying and displaying portions of XMI-defined metadata to end consumers. Bring in SVG for visualization and you'd really have some interesting capability (XMI to SVG transformations = nice pictures, automagically rendered by the tool.)
Boy, the MDR lists are ACTIVE lately, too! This is a lively effort with a lot of research and academic interest; commercial soon to follow I'm betting...
I won't be having time myself to work with this tooling, but I would be very interested in any experiences people have.