Loose coupling

Three phases of composites:
Modelling phase: semantic coupling: Strong(Service components), Weak(QoA, Governance Aspects), Non-Predominant
composition phase: Syntactic coupling: String and weak
execution phase: Physical coupling

Level of Loose coupling:

Loose coupling the implementation: Standard based, inter-operable specifications or protocol

Loose coupling the service contract: what happens when the service contract itself changes?difficult proposition, but there are plenty of best practices, service contract change management: Active management and service intermediaries and SOA governance.

Loose coupling the service policy: A policy is a form of metadata, as are contracts. changes to policy should be handled in the same way they handle changes to service contract: late-binding, service intermediary-enabled, registry-based, and governed. 

Loose coupling the process: Once you have a business process that composes a bunch of services together, we have another area of potential tight coupling. What happens when the process changes?The movement in the SOA and BPM markets has been towards separating the process definition layer from the underlying implementation.

Loose coupling the data schema: 

Loose coupling the infrastructure



Contextually coupling in EAI depends on:
Number of input data items
number of output data items
Dependency of service on other service
Services dependent on the service
Use of shared data
time dependency
Protocol uses


http://searchsoa.techtarget.com/tip/The-seven-levels-of-loose-coupling
http://www.zapthink.com/2006/10/03/the-role-of-transformation-services-in-soa/