The ability to create a subset schema is a perenial request I get from clients in the data integration space. Using standards developed within their industry consortia, they need to restrict the base schemas into ones that reflect the needs of their particular business scenarios. A subset schema (or "lite BOD" in the OAGIS lingo) is a schema that adds addition restrictions onto an existing schema. For example, removing optional elements that are not implemented can be done by deleting them from the schema. The resulting schema (called a subset) is still conformant to the original data model. And an xml instance of that subset schema will validate against the original data model schema.
Restrictions can include:
- removal of optional elements
- making optional elements required
- removing enumerated values from lists
- making a choice of elements into a sequence of one of the choices
It cannot include (because these are additions or extensions and not restrictions):
- making required elements optional
- adding additional enumeration values to a list
A tool called GEFEG can do this function. I wish there were others too. I've often wanted to create one myself using xforms and Xslt. But have never had enough time or someone committed help me do it. Anyone care to lend a hand and help me do this?
Data integration would really be enabled if we had this subsetting issue resolved.