BT User Experiences Jon Calladine 21st June 2005

BT Schema/Web Services evolution  Enabling the Infrastructure  Document Centric Services  3 rd Party Schema  Going to Market

Enabling the infrastructure  Wide industry support for the standards.  Interoperability was achieved. –RPC encoded  Code generation matched existing practice. –Productivity  Heterogeneity conquered –Legs to the legacy Was a success because :

Enabling the Infrastructure - 2  Heavy emphasis on testing –TestBench  Simplicity and restricted vocabulary  Some technologies depended on annotations –SOAPENC,:arrayType, unbounded arrays  Hadn’t fully embraced the concept of contract first coding.  Versioning began to be an issue But...

35 systems >30 registered robots 20,000 ‘dumb’ screens CSS Copper Records migration BMS (COTS) BMS Hub Pub/Sub Document Centric: Bearer Mgt System 15 WS(MQ) 170k calls/hour DCE RPC RMI Corba SISS MQSeries IP 3270

Document Centric  Objectives –Open re-usable services –Generic –Future proofed, Compliant = DocLit –Use of tools essential. (Range of clients + robots)  Constructs not supported, unpredictable behaviour –xs:all, xs:choice  Raised the bar on testing.  We had to constrain the schema designers.

Document Centric - 2  Avoid date & time types  Avoid user defined simple types  Namespace qualify schema elements  Always qualify schema references  Use venetian blind style schema  Nest repeated elements in their own container  Avoid xs:choice, xs:all  Use nillable=“true” & minOccurs= “0” for optional schema elements Toolkit Friendly Schema Vocabulary

3 rd Party schema  Non determinism, Invalidation of the UPA rule  Uses substitution groups extensively. –Toolkits don’t support this well  Mixed Content elements –Incorrectly represented/rejected  Result: we have departed from the spec. Service Provisioning Markup Language. OASIS Nov 2003

Going to Market  Mass market, volume services  Usable interfaces essential  Deregulation, equivalence of input  Not acceptable to support ‘best of breed’ only  Current BT B2B/ebXML implementations do not publish schemas but..  Customers are clamouring for them …. –To assist in processing the documents

Summary  The standard for describing Web service messages.  Code binding is an expectation amongst developers.  In our experience, XML Schema is implemented inconsistently in vendor tools, especially code generators.  There already is a lowest common denominator ‘profile’.  Practical interoperability testing is essential.  Better test pack is required. –Working around interoperability issues with vendor supplied tools is difficult.  Best Practices are required for a number of different aspects of schema e.g. Versioning.

C Q A X O N V Q J I D U A G T O X M A S N K X J R R X B C C M T A I C C T D D C S Z Z S B P X W L X P H A R S D T G R J L G A V U E P O E A R V B U J E Q W S B Q D Q I N W R S C O X U V Q N H U C L C E U R C R T A G P N E F J O C E H T O Z Y L V E N E T I A N B L I N D P I E C T Q T P W B T C R I N E F E A Q Z S C E U Y E G M W O Y F O P E L J A V H O N R R T O P C M N I L L A B L E T W E E L A W N L W E A V J X F D X I N A P U R U O N O H G R T XS:SEQUENCE XS:CHOICE HONOUR UPA COMPLEXTYPE MINOCCURS MIXEDCONTENT NAMESPACE QUALIFY NILLABLE VENETIANBLIND.