A benefit of Service Component Architecture (SCA) is that
you can use existing assets in an application, without having to change
the asset implementation. Many enterprises have application assets
developed using a variety of technologies and frameworks, including
assets previously deployed in a WebSphere® Application Server environment, which
is predominantly Java™ Platform,
Enterprise Edition (Java EE) or Java-centric. SCA supports several
service implementation technologies.
Before you begin
Determine which application files or artifacts (assets)
you want to deploy in an SCA application. If necessary, develop the
files or artifacts.
About this task
You can use SCA composites to:
- Reuse existing service implementations in the definition of an
SCA component for use in an SCA composite application.
- Enable the services within those technologies to be exposed or
use a service over the supported access bindings without changing
the business logic of the service.
Each component within an SCA assembly specifies the implementation
technologies which provide the specific business logic which implements
the services described in the component definition. A composite is
composed of 1-to-many components, each of which can be made up of
differing implementation technologies.
The Feature
Pack for SCA supports the following implementation programming
model technologies:
- implementation.java
- The implementation conforms to the SCA Java Component Implementation
specification.
- implementation.composite
- The implementation conforms to an SCA composite as defined in
the SCA Assembly Model specification.
- implementation.web
- The implementation conforms to Java EE 1.5 for Web modules and
Web archive (WAR) files.
- implementation.ejb
- The implementation conforms to Java EE 1.5 for Enterprise JavaBeans™ (EJB) 2.1 and 3.0
Stateless Session Beans.
- implementation.jee
- The implementation conforms to Java EE 1.5 for enterprise archive
(EAR) files.
- implementation.osgiapp
- The implementation conforms to the OSGi application programming
model as supplied with the Feature Pack for OSGi
Applications and JPA 2.0.
- implementation.spring
- The implementation conforms to the SCA Spring Component Implementation
specification.
WebSphere Application Server does
not include the Spring 2.5.5 package. You must obtain the Spring 2.5.5
package from the supplying vendor.
- implementation.widget
- The implementation is SCA-enhanced JavaScript contained within
an HTML page. Unlike the other implementation types, this component
runs on the server but it is returned to browsers from the server.
You wire services that JavaScript code references through SCA bindings.
Procedure
- Select the implementation type to use for the SCA component.
Table 1. Supported
SCA implementation types. Based on the implementation
technology of an asset, select the SCA implementation type to use
in the SCA component.
Asset implementation technology |
SCA implementation type |
SCA Java |
implementation.java |
SCA assembly |
implementation.composite |
Java EE application (EAR) |
implementation.jee |
Java EE EJB module, session bean, or message-driven
bean |
implementation.ejb |
Java EE Web module in a Java EE application |
implementation.web |
Enterprise bundle archive (EBA) artifact that
uses OSGi bundles and Blueprint components |
implementation.osgiapp |
Bean that follows the Java 2 Platform, Standard
Edition (J2SE) programming model in a Spring 2.5.5 container. |
implementation.spring |
HTML page enriched with JavaScript code that
contains SCA for return to a browser. An SCA service returns data
in JavaScript. The data can be in Atom collections or in JavaScript
Object Notation (JSON) format. |
implementation.widget |
- Configure the binding for the selected implementation type
and use the binding in an SCA component or application.
See
topics in the related links for information on specifying implementations
and bindings.
Results
The SCA composite makes the appropriate environmental transitions
to connect the implementation technology to any exposed bindings that
are also in the composite definition.
What to do next
Deploy the SCA composite or application in a business-level
application.