Schema Usage Experiences

Submitted by Faisal F. Waris, Ford Motor

Issues with Schema Usage

Experienced issues with the following schema constructs with various Web Services tools:

• choice
• ref to group
• ref to global element
• id, idref
• Substitution groups
• Some schema design guides do not recommend “type substitution” (i.e. use of xsi:type on instance documents) because of tooling related issues.
• key / keyref
• Derivation by extension of complex types where derived types define local elements with the same name as one of the parents’ elements.
• Union of simple types
• Derivation of simple types from ‘unioned’ base types.
• Cardinality on choice, sequence or all
• Anonymous types
• redefine
• Derivation by restriction of complex types

Issue with Schema Specification

Cardinality on xsd:sequence & xsd:choice

Depending on the mix of cardinality and ‘optionality’ of the group and those of contained elements, it is difficult/confusing to determine whether an instance document validates against the corresponding schema.