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INTRODUCING SCA

INTRODUCING SCA. Byungwook Cho (bcho@bea.com) Nov.2007. AGENDA. 1. SCA. 2. SCA Fundamentals. 3. Understanding Component. 4. Understanding Composite. 5. Using Policy. 6. SCA Implementation. 7. Example : Apache Tuscany. 1.SCA. Service Component Architecture

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INTRODUCING SCA

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  1. INTRODUCING SCA Byungwook Cho (bcho@bea.com) Nov.2007

  2. AGENDA 1 SCA 2 SCA Fundamentals 3 Understanding Component 4 Understanding Composite 5 Using Policy 6 SCA Implementation 7 Example : Apache Tuscany

  3. 1.SCA • Service Component Architecture • Define “A way to create components and a mechanism for describing how those components work together” • Owned by OASIS • Created by BEA,IBM,Oracle,SAP and others

  4. 2.SCA Fundamentals • COMPONENTS AND COMPOSITES • SCA application is built from one or more components • Components • Fundamental building block in SCA • can be implemented as Java classes, others written in C++, others defined in BPEL etc. • Components can be run in one or more processes in one or more machines • Composite • Specifies how those components can be combined into larger structures • Described in configuration file named SCDL(Service Component Definition Language-”skiddle” / *.compositefile) SCDL

  5. 2.SCA Fundamentals • DOMAINS • Runtime • SCA Container • Domain • SCA runtimes provided by single vendor and managed by single group. • It is similar concept with WLS or Tuxedo domain • A domain can contain one or more composites, each of which has components implemented in one or more processes running on one or more machines. Inter-domain communication

  6. 3.UNDERSTANDING COMPONENTS • SERVICES • Components implements some biz logic, exposed as one or more services. • Provides some number of operation that can be accessed by the component’s client • Can be provided in technology that’s used to implement comp. • Java Component / Java Interface • BPEL / WSDL

  7. 3.UNDERSTANDING COMPONENTS • REFERENCE • A component might rely on other services provided by other components in its domain or outside its domain. • Define an interface containing operations that this component needs to invoke • Advantages • Express component’s dependency. • Allow Dependency Injection. (cf. DI in spring framework) • PROPERTIES • Contains value that can be read by SCDL config file. • Example) • Locale,Currency

  8. 3.UNDERSTANDING COMPONENTS • BINDINGS • Define how communication happens between Service & reference • In same domain, component might or might not have explicitly specified binding. (runtime determines binding) • To communicate outside its domain, component must be specified one or more bindings for communication.

  9. 4.UNDERSTANDING COMPOSITE • COMPOSITE • Component is “atom” of SCA, Composite is “molecule” of SCA • Composite group components into useful combinations. • It can be further combined. • Component in composite might be run in same proccess,in different process on a single machine ,or in different processes on different machine. • WIRES • Wire is abstract representation of the relationship between reference and service. • PROMOTION • Service of composite • Just component expose services or references , a composite can also expose one or more services or references WIRE PROMOTION PROMOTION

  10. 4.UNDERSTANDING COMPOSITE • CONFIGURING COMPOSITE • All of relationship in a composite are expressed in SCDL conf. • ‘autowrire’ attribute • Indicate that the SCA runtime should automatically attempt to connect services and references defined by the components. • ‘wire’ element • Define explicit wires between components autowiring autowiring Promote Component1 / Service A as a service of this composite Promote Component2/ Service T, Component3/U as references of this Composite

  11. 5.USING POLICY • POLICY • To remove complication in interaction between parts of distributed application. Make things more manageable is to let developers user policies to specify their intent. To support this SCA provide SCA framework • SCA Framework Category • Interaction policies • How a component interacts with other components • Security, Reliable messaging • Applied to ‘bindings’ • Implementation policies • How a component behaves locally. • Transaction (* SCA 1.0 doesn’t define transactional policy) • SCA Framework • Policy can be declared in SCDL. • For Java SCA components, policies can also be defined using annotation. • SCA doesn’t define how policies should be described within a domain. • Between domains, policies can be specified in vendor-neutral form using WS-Policy.

  12. 6.IMPLEMENTING SCA • SCA IMPLEMENTATION • SCA runtime might provide a number of containers, one for each component technology it supports. • SCA runtime provides all bindings, allowing components created using any technology to use any available binding. • JBI • Java Business Interface • Make public interface between runtime & container. • Allow 3’rd party to create their own containers • OSGI • SCI runtime can be implemented by OSGI • OSGI defines how to package code into bundles, and while it’s also java-only,some creators of SCA runtimes might allow extensions such as a new binding to be added as an OSGI bundles • Tools • SOA Tools platform project • Create SCA-based development tools for eclipse JBI

  13. 7.Example : Apache Tuscany Impl • Apache store SCA application

  14. 7.Example : Apache Tuscany Impl SCDL Catalog.java service & binding service CatalogImpl.java properties reference component

  15. 7.Example : Apache Tuscany Impl • Composite

  16. REFERENCE • Reference • July.2007, David Chappell, Introducing SCA. • Reference Implementation • Apache tuscany : incubator.apache.org/tuscany/ • Fabric3 : incubator.apache.org/tuscany/ • SCA tools • http://www.eclipse.org/stp/ • OSGI • http://www2.osgi.org/Specifications/HomePage • JBI • http://jcp.org/en/jsr/detail?id=208 • For more • Various binding types • Hessian,Burlap,ATOM,REST,RSS,Json rpc,dojo

  17. Thank you !! Our team blog : http://dev2dev.tistory.com

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