BT User ExperiencesJon Calladine

21st June 2005

BT Schema/Web Services evolution

Enabling the Infrastructure Document Centric Services 3rd 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 robots20,000 ‘dumb’ screens

CSSCopper Records

migration

BMS(COTS)

BMS HubPub/Sub

Document Centric:Bearer Mgt System

15 WS(MQ)170k calls/hour

DCE RPCRMI

CorbaSISS

MQSeriesIP

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

3rd 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Current BT B2B/ebXML implementations do not publish schemas but ..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 TO 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:SEQUENCEXS:CHOICEHONOUR UPACOMPLEXTYPEMINOCCURSMIXEDCONTENTNAMESPACEQUALIFYNILLABLEVENETIANBLIND....