BT User Experiences

1
BT User Experiences

• Jon Calladine
• 21st June 2005

2
BT Schema/Web Services evolution

• Enabling the Infrastructure
• Document Centric Services
• 3rd Party Schema
• Going to Market

3
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

4
Enabling the Infrastructure - 2
But...

• Heavy emphasis on testing
• TestBench
• Simplicity and restricted vocabulary
• Some technologies depended on annotations
• SOAPENC,arrayType, unbounded arrays
• Hadnt fully embraced the concept of contract
  first coding.
• Versioning began to be an issue

5
Document Centric Bearer Mgt System

35 systems gt30 registered robots 20,000 dumb
screens
DCE RPC RMI Corba SISS MQSeries IP 3270
CSS Copper Records
6
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
• xsall, xschoice
• Raised the bar on testing.
• We had to constrain the schema designers.

7
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 xschoice, xsall
• Use nillabletrue minOccurs 0 for optional
  schema elements

8
3rd Party schema
Service Provisioning Markup Language. OASIS Nov
2003

• Non determinism, Invalidation of the UPA rule
• Uses substitution groups extensively.
• Toolkits dont support this well
• Mixed Content elements
• Incorrectly represented/rejected
• Result we have departed from the spec.

9
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• Current BT B2B/ebXML implementations do not
  publish schemas but ..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

10
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.

11
XSSEQUENCE XSCHOICE HONOUR UPA COMPLEXTYPE MINOC
CURS MIXEDCONTENT NAMESPACE QUALIFY NILLABLE VENET
IANBLIND . . . .
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