SOA Fundamentals For Java DevelopersAlexander Ulanov, System Architect

Odessa, 30 September 2008

SOA Fundamentals For Java DevelopersAlexander Ulanov, System Architect

Odessa, 30 September 2008

What is SOA?What is SOA?

• Software Architecture style aimed on• Reuse• Growth• Interoperability

• Maturing technology framework supporting the architecture

• Next evolutionary step of enterprise information systems

• An effective mean to close the gap between business and IT

Enterprise EcosystemEnterprise Ecosystem

SOA

SOA for IT-resources integrationSOA for IT-resources integration

• Common infrastructure based on open and widely-adopted standards

• Reuse of enterprise information services and other software assets

• Going beyond the enterprise – integration with:• Partner’s IT• Global chain of information services providers and consumers

• Unified policies to all services and applications• Service level agreements

• Integrating legacy systems • Smooth transition

SOA for Business-IT AlignmentSOA for Business-IT Alignment

• Software resources (services) are designed as a business function

• The services are orchestrated to fulfill particular business-process

• This involves:• Services are understandable in terms of business (visibility)• Local changes in IT as response to new or changed business-

process• Events in information system can be simply abstracted to

business key performance indicators (KPI)

Reference ArchitectureReference Architecture

Principles of Service DesignPrinciples of Service Design

• Top-down: from business-processes to services contract

• Bottom-up: from existing software assets – how to fulfill the contract

Design by ContractDesign by Contract

• Contract• Interface definition

• Operations• Data types

• Policy assertions• Identify behavior

attributes

• “Contract first”

Loose CouplingLoose Coupling

• Service contracts impose low consumer coupling requirements

• Negative coupling:• to implementation of service

logic• to vendor technology• to resources of the

implementation environment• to parent business-process

AutonomyAutonomy

• High level of control over underlying runtime execution environment

• Gradual transformation• Reducing shared resources access• Increasing physical isolation

• Autonomy is especially important to the effectiveness of service compositions

ComposabilityComposability

• Fundamental principle - system decomposition and separation of concerns

• Ability to act as an effective composition member so that it can support the realization of new business requirements that can be fulfilled by the assembly of service compositions

• That involves service properties:• Designed from business-process

model• Autonomous• Loosely coupled

• Composition design pattern:• Functional call

StatelessnessStatelessness

• Concurrent access to statefull service is a scalability issue

• Deferring the management of state information when necessary• Empowers composition and reuse

AbstractionAbstraction

• General categories of information about service:• Functional• Technology• Programmatic• Quality of Service

• Service contracts contain only essential information

• Information about services is limited to what is published in service contracts

ReusabilityReusability

• Services contain and express agnostic logic• Contract centralization• Logic centralization

• Can be positioned as reusable enterprise resources• Inventory (Repository)

• To support reuse• Conservative

• Specify requirements to reuse that service

• Governance effort• Cultural change

• Developers encouraged to discoverfor reuse

DiscoverabilityDiscoverability

• Services are supplemented with communicative meta-data• Functional• Quality of Service

• And can be effectively discovered and interpreted• Service Registry

• Similar process for run-time (dynamical binding)

Standardized Service ContractStandardized Service Contract

• Same contract design standards within service inventory (repository)

• Standards enable automated policies governance

ProcessProcess

SOA ProgramSOA Program

Service Life-Cycle ManagementService Life-Cycle Management

Service InfrastructureService Infrastructure

Communication ProtocolsCommunication Protocols

• WS-*• Large set of standards issued by OASIS

• Security, reliable messaging, policies, etc..• SOAP – basic communication protocol• Standard Java API – JAX-WS

• RESTful Services• JAX-RS

• JMS

• EJB (RMI/IIOP)

• etc

Exposing and Calling Web-Services in JavaExposing and Calling Web-Services in Java

• JAX-WS: server • Expose service from

• EJB• POJO• Spring component

• From WSDL to code vs. from code to WSDL

• JAX-WS: client

Infrastructure FunctionsInfrastructure Functions

• Mediation & Messaging• Synchronous and

asynchronous message delivery

• Transport protocol adapters• HTTP, SOAP, SMTP/POP3,

JMS, FTP, …

• Caching

• Security• End-to-end• Message-level

• Dynamical binding

• Service Composition• Data transformation• Content-based routing• Event-flow orchestration

• Management• Service Provisioning• Traffic management• Monitoring, Logging,

Alerting

Apache Synapse / WSO2 ESBApache Synapse / WSO2 ESB

• Lightweight ESB • Mediation• Transformation (XSLT, XQuery)• Security (WS-Security)

Service Component Architecture (SCA)Service Component Architecture (SCA)

• Programming model seen by application code remains the same regardless to protocol

Service Component Architecture (SCA)Service Component Architecture (SCA)

• Assembly:• Packaging component as a

service• Combining into composites• Dependency Injection• Wiring, Auto-wiring• Properties

• Annotations• @Remotable, @Reference,

@Property…• SCDL configuration files

Service Component Architecture (SCA)Service Component Architecture (SCA)

Advantage over Spring:• remote components• multiple protocols for communication • variety of programming languages for application components• support for an asynchronous programming model • flexible application of policy to components and to communications

Open-Source Infrastructure ProductsOpen-Source Infrastructure Products

• JAX-WS Containers• Java 6 SDK WS-Container• Sun JAX-WS (Metro)• Apache CXF

• ESB• Apache ServiceMix

• IONA Fuse ESB• Mule ESB• Apache Synapse

• WSO2 ESB• Sun’s OpenESB• JBoss ESB

• SCA container• Apache Tuscany

• Messaging• Apache Active MQ

• Registry• ApacheDS (LDAP)• Sun OpenDS (LDAP)• Apache jUDDI (UDDI)

• Registry/Repository• Mule Galaxy• WSO2 Registry

What else is worth to study?What else is worth to study?

Questions?Questions?