SCA Bindings and the Enterprise Service Bus


A binding is a set of details on how to structure and transport a message. When used in relation to WSDL, the word "binding" identifies only a transport protocol or the software that invokes a transport protocol. When used in relation to SCA, however, the word identifies not only those details but also the location of the accessed queue, application, or service implementation. The word is also used informally to refer to a type of access software, as in the phrase "use the JMS binding to access a queue."

Your SCA-compliant products may have bindings for the following software, among others:

  • HTTP, which allows a connection to a Web service

  • Java EE Connector Architecture (JCA), which allows a connection to an adapter from a service that runs on the Java EE platform

  • Java Remote Method Invocation over Internet Inter-ORB Protocol (JMI/IIOP), which allows a connection (for example) to an Enterprise Java Bean running on a Java application server

  • Java Messaging Service (JMS), which allows access to a message queue

To guide data transfer to a service that is external to the SCA Domain, you must specify an explicit binding. No default is available. To guide data transfer within the Domain, however, the assembler usually chooses the SCA binding, which causes the SCA runtime to decide how to fulfill the transfer. The assembler can specify that setting explicitly or by default.

When the SCA binding is in effect, the SCA runtime might always select the same fixed binding such as HTTP or might select a protocol that is appropriate for a specific case. For example, the runtime might select a secure protocol when two components are transferring financially sensitive data. Use of SCA binding is recommended because the selection is simple for the assembler and gives maximum flexibility to the SCA runtime. For details on configuring the SCA runtime, see your product documentation.

You can specify a binding other than SCA binding for data transfers within the SCA Domain. You might want to select a different binding, for example, if you are transferring financially sensitive data but your runtime product does not provide a component-specific way to configure the behavior caused by SCA binding.

At run time, services can send and receive messages on an Enterprise Service Bus (ESB), which is software that accesses HTTP, JCA, and so on. SCA can interact with an ESB or can operate in its absence.




SOA for the Business Developer. Concepts, BPEL, and SCA
SOA for the Business Developer: Concepts, BPEL, and SCA (Business Developers series)
ISBN: 1583470654
EAN: 2147483647
Year: 2004
Pages: 157
Authors: Ben Margolis

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