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Messaging & Web Services an Architectural View
John Arnett, MScStandards ModellerInformation and Statistics DivisionNHSScotlandTel: 0131 551 8073 (x2073)mailto:[email protected]://isdscotland.org/xml
Contents
• XML Usage• XML Applications• Messaging and Web Services• Interaction Models• Message Construction
XML Usage
• Key features– Human readable – Structured and searchable– Separates data from
presentation– Self-describing – Extensible – any number of
tags allowed– Meta-markup language
XML Usage
• Open standard, promoted by many vendor-neutral organisations, incl.– W3C– OASIS (Organization for Structured
Information Standards)– HL7 (Health Level 7)– OMG (Object Management Group)– UK Government
XML Usage
• Widely supported by software vendors and open source groups, incl.
XML Applications
Data Storage & Content
ManagementMessaging & Web Services
Messaging & Web ServicesPresentati
on
PresentationPresentati
on
Presentation
Application Logic
Application Logic
Application Logic
Application Logic
• XML Messages– Ideal for data interchange
•Text based•Open•Self describing•Extensible
– Exchanged between applications on the same network or over the Internet/Extranet
Messaging and Web Services
Messaging and Web Services
• Web Services– Set of emerging standards, incl.
SOAP, WSDL and UDDI– Allow systems to communicate
over the internet using XML messages
– Used for•remote service requests/calls •enterprise application integration
•business process integration
Messaging and Web Services
• SOAP– Lightweight, XML-based
protocol for exchanging information over the internet
– Language, platform and transport independent
– v1.2 W3C Recommendation
Messaging and Web Services
• WSDL (Web Services Definition Language)– XML-based language for describing
services available on the internet
• UDDI (Universal Description, Discovery and Integration) directory services– Information Services– Operations
SenderSender
Interaction Models
Channel
MessageMessage
ReceiverReceiver
• Message Channel
Interaction Models
• One-way (“fire-and-forget”)– non-blocking, asynchronous model
ConsumerConsumer ProviderProvider
Message
Interaction Models
• Synchronous Request/Response– RPC
ConsumerConsumer ProviderProvider
Request
Response
Interaction Models
• Call Back– Asynchronous conversations
ConsumerConsumer ProviderProvider
Request with correlation id
Acknowledgement
Response
Acknowledgement
Interaction Models
Telephone-like Post Office-likeSynchronous Asynchronous
Tighter coupling Loose couplingStrongly typed Document-basedFast feedback Slower feedback - call-return - queuing and
routing
RPC Message-oriented
Interaction Models
• Point-to-Point– One input channel to one
output channel– Message sent to 1 receiver
only– Message sent directly or via
router/queue
Interaction Models
• Multi-Point– One input channel to many
output channels or subscribers– Copy of message sent to each
subscriber– Message published via router /
topic
Message Construction
• Message Types– Document - transmits
structured or unstructured data – Command - specifies a function
or method to invoke on the receiver
– Event - notifies receiver of some event of interest, e.g. an acknowledgement
Message Construction
• High Level Information Model– HL7 v3 RIM– CEN (European) Standards– e-GIF (UK Government)
Message Construction
• Message Content– Clinical guidelines, e.g. SIGN– National Data Definitions, e.g.
SMR– Consultation with user groups,
professional bodies and manufacturers
– Other sources, e.g. existing EDIFACT messages
Message Construction
• Standard XML Vocabularies– Health Care
•NHSS architectural schemas•Health Level 7 (HL7) v3
– Government•UK GovTalk schemas
– International•UNeDocs Code Lists XML - units of measurement, etc
Message Construction
• Message Schemas– Messages
•Referral•Waiting Times
– Message Structures •NHSS •HL7 CDA •Government Gateway
Message Construction
SOAP Envelope
SOAP Header
SOAP Body
Message Structure
Message Content
Find Out More
• Scottish Health and Community Care XML Steering Group– www.isdscotland.org/xml
• SCI XML Standards– www.show.scot.nhs.uk/sci
• GovTalk Schemas and Standards– www.govtalk.gov.uk
• Health Level 7– www.hl7.org
Messaging and Web Sevices
• W3C Web Services Activity– www.w3.org/2002/ws
• Web Services Interoperability– www.ws-i.org
Communication Models
• WS-I Usage Scenarios– www.ws-i.org/SampleApplications/SupplyChainManagement/2003-04/UsageScenarios-1.01-BdAD.doc
• Enterprise Integration Patterns– www.enterpriseintegrationpatterns.
com
