CERN – European Organization for Nuclear Research

IT Department – Administrative Information Services

Service Oriented ArchitectureService Oriented Architecturedefinition and main conceptsdefinition and main concepts

Derek Mathieson

IT Department

CERN

Some content from Peter Campbell, ANZ Banking Group Australia

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Problem StatementProblem Statement

Promote reuse– Open architecture

Systems Integration– Link-up Enterprise Information Systems

Interface with other companies– B2B transactions and processes

Increase Agility– Acquisition and/or merger– Changing Business models

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SOA – A definition from the W3CSOA – A definition from the W3C

Typical characteristics of a SOA: Logical view

– defined by what a service does Platform neutral

– often XML based Description orientation

– service description is machine-processable. Message orientation

– defined in terms of the messages exchanged between requester and provider

Granularity– Coarse-grained

Network orientation– not an absolute requirement.

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SOA Conceptual ArchitectureSOA Conceptual Architecture

Binding Choices: Static binding

– Not loosely coupled as the consumer will fail if the service is offline

Dynamic binding– Can allow runtime failover and load balancing– Service discovery at runtime can have serious performance issues– Less commonly used

ServiceConsumer

ServiceBroker(UDDI)

ServiceProvider

ServiceContract(WSDL)

Client Service

Bind & invoke

Register(UDDI Publish save_xxx)

Find(UDDI Inquiry find_xxx)

SOAP

XML

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What are Web Services?What are Web Services?

XML XML

Application 1 Application 2

Applications communicating over the internet usingan agreed message format – encoded as XML

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Packaging – SoapPackaging – Soap

HTTP Post

SOAP Envelope

SOAP Body

SOAP Header

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Packaging – SoapPackaging – Soap

<s:Envelope xmlns:s="URN"><s:Header>

<s:Transaction xmlns:m="URN"> <m:TransactionID> 17389 </m:TransactionID

></s:Transaction>

</s:Header> <s:Body>

<n:purchaseOrder xmlns:n=“URN”><n:item>socks</n:item><n:quantity>1</n:quantity><n:unitPrice>3.95</n:unitPrice>

</n:purchaseOrder></s:Body>

</s:Envelope>

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Description – WSDLDescription – WSDL

Web Services Description Language“Web Services Description Language

(WSDL) provides a model and an XML format for describing Web services.” w3c.org

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Description – WSDLDescription – WSDL

Messages

Types

Operations

Encoding

Endpoint

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TypesTypes<types> <schema targetNamespace="stockquote.xsd" xmlns="XMLSchema"> <element name="TradePriceRequest"> <complexType>

<all> <element name="tickerSymbol" type="string"/>

</all> </complexType> </element> <element name="TradePrice"> <complexType> <all><element name="price" type="float"/>

</all> </complexType> </element> </schema></types>

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MessagesMessages

<message name="GetLastTradePriceInput">

<part name="body" element="xsd1:TradePriceRequest"/>

</message>

<message name="GetLastTradePriceOutput">

<part name="body" element="xsd1:TradePrice"/>

</message>

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OperationsOperations

<operation name="GetLastTradePrice">

<input message="tns:GetLastTradePriceInput"/>

<output message="tns:GetLastTradePriceOutput"/>

</operation>

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EncodingEncoding

<binding name="StockQuoteSoapBinding" type="tns:StockQuotePortType">

<soap:binding style="document" transport="http://schemas.xmlsoap.org/soap/http"/> <operation name="GetLastTradePrice"> <soap:operation soapAction="http://example.com/GetLastTradePrice"/> <input> <soap:body use="literal"/> </input> <output> <soap:body use="literal"/> </output> </operation></binding>

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EndpointEndpoint

<service name="StockQuoteService"> <documentation>Stock service</documentation> <port name="StockQuotePort" binding="tns:StockQuoteSoapBinding"> <soap:address location="http://example.com/stockquote"/> </port></service>

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Discovery – UDDIDiscovery – UDDI

Universal Description, Discovery and Integration

A UDDI Server acts as a registry for Web Services and makes them searchable.

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Discovery – UDDIDiscovery – UDDI

UDDI RegistryInquiry

Publish

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Discovery – UDDIDiscovery – UDDI

UDDI RegistryInquiry

Publish

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SOA and Web servicesSOA and Web services Web services

– delivers key standards for implementing SOA XML

– Ideal candidate for loosely coupled inter-application data sharing The WS-* Standards Family

– EAI & B2B

Services architectureService contractMessage basedService directoryProtocol independentCoarse grained

Process orchestration(WS-BPEL)

SOA“The architecture”

RPC interactionsBinary XML

Web services specsWSDLSOAP & XMLUDDI HTTPDoc literal binding

Web services“The plumbing”

Author: Peter Campbell, ANZ Banking Group Australia

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Web Services FrameworkWeb Services Framework

The Web Services Framework consists of the following technologies:

Wire stack

Descriptionstack

Discoverystack

Technologies that allow a service requestor to discover a service provider

e.g. UDDI. Production usage for static binding. Evolving to cover dynamic binding & discovery

Technologies that allow a common understanding between service requestor and service provider

Technologies that determine how a message is sent from the service requestor to the service provider

e.g. WSDL. Production usage. Evolving to cover security and other additional functions

e.g. SOAP. Production usage. Evolving to cover advanced messaging functions

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Service

Service Interface

Service implementationService implementation

A service is a component built for reuse by other components in different execution contexts.

Services might need to be able to distinguish messages from individual consumers and also be able to correlate those messages into meaningful conversations.

Implementation details are hidden from the consumer

Provides service identification, definition of parameters, and passing results back to the consumer

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Services and business processesServices and business processes

Services can be linked to form business processes using process orchestration

Business Process Orchestration

BusinessServices

TechnicalServices

Get customer

details

“Open account for customer”

Getaccount

type

Add account tocustomer

Locatecustomer

record

Checkcustomer

status

Presentation – user interface

Create Customer-Accountrecord

Lookupaccount

typetable

Retrieveaccountdetails

Business Process

Coarse Grained

FineGrained

Service Orchestration(Process Orchestration)

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Service ReuseService Reuse

A service can be reused across multiple channels

AccountEnquiry

(staff assisted)

AccountEnquiry

(self service)

Business services

DeliveryChannels

CustomerService

AccountEnquiry

(self service)

ATM

Presentation layer

Branch

InternetInternet

Get AccountBalance

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Integration roadmap to SOAIntegration roadmap to SOA

1. Point to point systems

3. Service Oriented Architecture & Enterprise Service Bus

Enterprise Service Bus

Routing

Services

Custom applications

Packageapplications

BusinessProcess

Orchestration

Adapter

Shared

System

TransformationAdapter

Legacy

System

Service(Process)

orchestration

HTTP

Internet

Business RulesEngine

App A(J2EE)

Legacy

ApplicationLegacy

Application

App B(.Net)

App D

(J2EE)

Warehouse

Finance

Sales App C

(.Net)

Partner

2. Message-based middleware with integration broker

Service Bus / MOM

App AApp B

Legacy

System

Shared

System

Adapter

Adapter

App C

App D

Sales

PartnerWarehouse

Finance

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Integration – point to point systemsIntegration – point to point systems

Advantages– Connectivity, some integration

Issues:– Tightly coupled– Hard to change– Lack of common interface standards– Security issues– Limited integration and sharing of data– Single points of failure can bring down whole system– Not asynchronous – poor performance and scalability– Silo-based systems aligned with specific business units– Fine-grained services often not reused across the enterprise– Different integration formats

App A

Legacy

ApplicationLegacy

Application

App B

App D

Warehouse

Finance

Sales

App C

Partner

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Message Oriented MiddlewareMessage Oriented Middleware

Advantages–Common application interface (API)–Provides some abstraction between consumer and provider–Asynchronous–Transformation–Content-based routing–Reuse services & transactions

Issues:–Proprietary service definition–Messages dependent on middleware–External (B2B) connectivity difficult–Some consumer-channel-message coupling–Limited service repository and manual registry

MOM

App AApp B

Legacy

System

Shared

System

Adapter

Adapter

App C

App D

Sales

PartnerWarehouse

Finance

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Service Oriented Architecture & Enterprise Service BusService Oriented Architecture & Enterprise Service Bus

Enterprise Service Bus

Routing

Services

Custom applications

Packageapplications

BusinessProcess

Orchestration

Adapter

Shared

System

TransformationAdapter

Legacy

System

Service(Process)

orchestrationInternet

Business Rules Engine

Advantages– Service bus implementation– Service definition– Common application interface (API)– Provides some abstraction between

consumer and provider– Asynchronous– Transformation– Content-based routing– Reuse services & transactions

– Integration broker– Standard service description (via WSDL)– External (B2B) connectivity simplified via

Web services– Security and identity management provided

by WS-Security standards– Support for Event Driven Architecture

HTTP

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Enterprise Service Bus (ESB) helps manage large number of services by providing horizontal value-adds such as:– Security– Transactions– Reliability– Service Virtualization

• Load Balancing• Message Distribution (Fan out and in)

What is ESB?What is ESB?

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How does ESB Work?How does ESB Work? ESB works by using the extension mechanisms

built into SOAP:1. Message syntax and semantics can be extended with

headers2. Messages can be intercepted and worked on by

intermediaries Headers are not just syntax as in Mail Headers

– Semantics of who may/must process headers allows standardization of extensions. E.g., WS-Security

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Event Driven Architecture (EDA)– Event triggered messages– Sender & Receiver have no knowledge

of each other– Queued messaging

• Store-and-Forward• Events published to a topic may be sent to

zero, one or many interested recipients.

Event Driven Architecture Event Driven Architecture (EDA)(EDA)

A

Subscriber

X

Y

Publisher

Publisher

msg1

msg2msg2

msg1

Subscribe to: msg1 & msg2

Broker

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SOAP Interaction PatternsSOAP Interaction Patterns

ServerClient

1. Request-response (client to server and back)

Request

Response

ClientServer

2. Notification-response (server to client and back)

Notification

Response

ServerClient

3. One way(from client to server)

One way

ClientServer

3. Notification(from server to client)

Notification

SOAP supports the following four interaction patterns:

SOAP is able to support both remote procedure call (RPC) and document-style interactions, in either a synchronous or asynchronous fashion

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ConclusionsConclusions

SOA– Is not a NEW idea

• But the pieces are now in place

– Facilitates• Modular design / architecture

Many implementations– Commercial & Open Source

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Thank YouThank You

For More InformationFor More Information

Browse to:http://www.w3.org/TR/ws-arch

or Email:Derek.Mathieson@cern.ch