BT User Experiences

BT User Experiences Jon Calladine 21st June 2005

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

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

Enabling the Infrastructure - 2 But... • 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

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

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 Toolkit Friendly Schema Vocabulary • 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

3rd Party schema Service Provisioning Markup Language. OASIS Nov 2003 • 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.

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equivalence of input • Not acceptable to support ‘best of breed’ only • Current BT B2B/ebXML implementations do not publish schemas but ..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.

XS:SEQUENCE XS:CHOICE HONOUR UPA COMPLEXTYPE MINOCCURS MIXEDCONTENT NAMESPACE QUALIFY NILLABLE VENETIANBLIND . . . . 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

BT User Experiences