Maintaining XML Data Integrity in Programs An Abstract Datatype Approach

In service-oriented loosely coupled distributed information systems, the format and semantics of the exchanged data become more and more important. We envisage that there will be an increasing number of general and domain-specific XML-based data formats for service-oriented computing. A typical example is a tax declaration form. If the schemas defining the formats specify structural and additional integrity constraints, we speak of constrained XML. The paper describes a technique for an integration of constrained XML data into programming, which is able to handle integrity constraints. Our technique allows to automatically check the correctness of programs manipulating constrained XML data. In our approach, constrained XML data is treated like an abstract data type with an interface of schemaspecific procedures. Programs use these procedures to manipulate the XML data. The preconditions of the procedures guarantee that procedures maintain the constraints. Our approach allows to automatically generate the preconditions and to simplify them to a minimal form. The technique is based on a path representation and logical embedding of XML data. The weakest precondition generation is implemented and exploits an SMT-solver for simplification.