WfMC Issues

During the course of implementing WAPI 1.0 and XPDL 1.0 support in OBE a number of ambiguities and contradictions in WfMC specifications came to light, of which it is as well to be aware.

XPDL Issues

This section discusses issues with the XPDL 1.0 specification and where appropriate provide guidance for minimizing their impact on the semantic portability of processes expressed in XPDL; our discussion uses XPath notation to identify elements and their attributes. In some cases valuable semantics present in XPDL's predecessor WPDL have been lost or distorted. The issues fall into four categories:

Missing Defaults

These are cases where the Schema defines an element or attribute as optional but does not specify the default value.  For clarity and portability it is advisable for XPDL instance documents to specify explicit values for such attributes. OBE's defaults are underlined in the following.

Undefined Semantics

These are cases where the Specification or Schema does not provide a clear and unambiguous definition of semantics.

Schema Errors and Ambiguities

These are cases where the Schema or Specification references undefined items, or where the definition is weak or ambiguous.

Schema Omissions and Inconsistencies

These are cases where the Schema uses XML Schema ineffectively or inconsistently.


The above information is reproduced with permission from John Wiley & Sons.