Ümit Yalçınalp David Burdett Gunther Stuhec NetWeaver Platform EcoSystem Group, SAP Labs XML Schema User Experience Report

 SAP AG 2005,XML Schema user experiences, Ümit Yalçinalp/ 2 XML Schema and SAP SAP provides Business Applications and Business Applications Platform The backbone of SAP‘s Enterprise Services Architecture: XML and Web Services Our usage of XML Schema is multidimensional Data definitions for applications Integration using Web Services Multi-language platform Our experience can be summarized with respect to Usability Implementation Language Bindings

 SAP AG 2005,XML Schema user experiences, Ümit Yalçinalp/ 3 Usability Development of Business Vocabularities is a Key Focus Need guidelines and rules for building data definitions Reduction of variability and complexity is necessary Design decisions/approaches can not be arbitrary for authoring Must be toolable, extensible within our platform Predefined Vocabularies are building blocks for applications UN/CEFACT Core Component specification Adopted by all major vertical industries standards groups Basis for SAP Business Applications Has defined naming convention and feature subset = Profile of XML Schema Profile examples:  Limits use of extension or restriction  No substitution group, redefine, xs:any Three important aspects  Business documents extensible in dimensions to handle domain specific needs: industry, business process, product, etc.  Limits unbound occurances of choice, sequence  Includes guidelines for handling business document versioning !

 SAP AG 2005,XML Schema user experiences, Ümit Yalçinalp/ 4 Usability (cont) Versioning is a major problem we encounter everywhere: Namespaces Application Specific extensions, attributes in schemas or components Please Nail down Semantics of Versioning first: Major versions = constitute significant and/or non-backwards compatible changes Minor versions = used for compatible changes within a major version, monotonic This Problem must be solved ASAP Otherwise, versions of components and vocabularies will NOT be integrate able in the very near future

 SAP AG 2005,XML Schema user experiences, Ümit Yalçinalp/ 5 Implementation and Usability Comments on Some Schema Features: Redefine (IU, HTI) Substitution Groups (IU, HTI) Block/Blockdefault (IU) Occurance (Choice/Sequence) (HTI) NOTATION (IU) Key/Field/XPath/Selector (high overhead for runtime validation ) HTI=hard to implement, IU=infrequently used

 SAP AG 2005,XML Schema user experiences, Ümit Yalçinalp/ 6 Language Bindings SAP has two language stacks: ABAP and Java Two aspects of binding are considered: XML2Language Language2XML Round tripping, serialization/deserialization is not uniform In our own platform, a profile (based on Core Components) is adopted for developing building applications WS Proxies still need to deal with XML Schema in its entirety!

 SAP AG 2005,XML Schema user experiences, Ümit Yalçinalp/ 7 Conclusion/Recommendations Two Recommendations: Formalize profiles of XML Profiles are inevitable and useful  For language bindings  For vocabularies  For specific user communities Should include:  Formal method of defining a profile  Identifying that a profile has been used in a Schema Instance Benefit  Enables tools to be developed that are optimized to the use of that schema profile  Enables development of optimized XML schema processors for some applications Versioning must be Addressed!