Service Oriented Architecture

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Service Oriented Architecture

► ArchitectureArchitecture

► ServiceService

► SOA – Service Oriented ArchitectureSOA – Service Oriented Architecture

Architecture

► What is Software Architecture ?■ Collection of the fundamental decisions about a software Collection of the fundamental decisions about a software

product/solution designed to meet the project‘s goals and quality product/solution designed to meet the project‘s goals and quality attributesattributes

■ The architecture includes the main components, their main attributes, The architecture includes the main components, their main attributes, and their collaboration (i.e. interactions and behavior) to meet the and their collaboration (i.e. interactions and behavior) to meet the quality attributes. quality attributes.

■ Architecture can and usually should be expressed in several levels of Architecture can and usually should be expressed in several levels of abstraction (depending on the project's size).abstraction (depending on the project's size).

■ Architecture represents the set of earliest design decisionsArchitecture represents the set of earliest design decisions• Hardest to changeHardest to change• Most critical to get rightMost critical to get right

Architecture

Architecture

Quality Attributes

Technology

Patterns & Anti-patterns

Principles

Community experienceCommunity experience

StakeholdersStakeholders

ArchitectArchitect

people

A “deliverable”

Produce

Key

Is an input

Constraints

Service

► What is a service ?What is a service ?

■ A facility supplying some public demand A facility supplying some public demand

■ The work performed by one that The work performed by one that serves HELP, USE, BENEFIT HELP, USE, BENEFIT

■ A Windows Service?A Windows Service?• RPC Locator, EventLog, DHCP ClientRPC Locator, EventLog, DHCP Client

■ Software Service?Software Service?• Distribution Service, Alert ServiceDistribution Service, Alert Service• Security Service, Log ServiceSecurity Service, Log Service

Service Oriented Architecture

"Network"

COPCOPCOPCOP

Nav.Nav.Nav.Nav.

AlertsAlertsAlertsAlerts

Prot.Prot.Prot.Prot.

Service Oriented Architecture

► What is SOA ? What is SOA ?

■ Architectural StyleArchitectural Style

■ For building distributed systemsFor building distributed systems

■ Loosely coupled componentsLoosely coupled components

■ Message based communicationMessage based communication

High Level View

Service

describes

End Point Exposes

Messages Sends/Receives

Contracts

Binds to

Service Consumer

Implements

Policy Governed by

Sends/Receives

Adheres to

Component

Relation

Key

Understands

Serves

Services and Systems

► A service is a program you interact with via message A service is a program you interact with via message exchangesexchanges■ Services are built to lastServices are built to last■ Encompass a business perspectiveEncompass a business perspective■ Stability and robustness are criticalStability and robustness are critical

► A system is a set of deployed services cooperating in a A system is a set of deployed services cooperating in a given taskgiven task■ Systems are built to changeSystems are built to change■ Adapt to new services after deploymentAdapt to new services after deployment

Services

► Services are AutonomousServices are Autonomous■ Services are as self sufficient as possibleServices are as self sufficient as possible

► Governed by PoliciesGoverned by Policies■ The fact that I can, doesn’t mean I will.The fact that I can, doesn’t mean I will.■ Explicit statements of capabilities and requirements.Explicit statements of capabilities and requirements.

• SecuritySecurity• Messages behaviorMessages behavior• Level of serviceLevel of service• Limited by the actual service capabilitiesLimited by the actual service capabilities

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Services

► Endpoint Endpoint ■ An address, a URI, a specific place where the service can be An address, a URI, a specific place where the service can be

found. found. ■ A specific contract can be exposed at a specific endpoint.A specific contract can be exposed at a specific endpoint.

► MessageMessage■ Services revolve around MessagesServices revolve around Messages

• Services are “Black Boxes”Services are “Black Boxes”• Messages go in and outMessages go in and out• The rest is an Implementation DetailThe rest is an Implementation Detail

■ IdempotenceIdempotence• Idempotent Means It’s OK to Arrive Multiple TimesIdempotent Means It’s OK to Arrive Multiple Times

– As Long as the Request Is Processed at Least Once, the Correct Stuff As Long as the Request Is Processed at Least Once, the Correct Stuff OccursOccurs

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Services

► Service ContractService Contract■ Messages & Formats Messages & Formats ■ Message Exchange PatternsMessage Exchange Patterns■ Where is a service located (Address)Where is a service located (Address)■ Protocol & content format (Binding)Protocol & content format (Binding)

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Advantages

► AdvantagesAdvantages■ Due to its platform independence, it allows companies to use Due to its platform independence, it allows companies to use

the software and hardware of their choice .the software and hardware of their choice .

■ There is no threat of vendor lock-in There is no threat of vendor lock-in

■ SOA enables incremental development, deployment, and SOA enables incremental development, deployment, and maintenance. maintenance.

■ Companies can use the existing software (investments) and Companies can use the existing software (investments) and use SOA to build applications without replacing existing use SOA to build applications without replacing existing applications applications

■ The training costs are lowThe training costs are low

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Thank you