Flexible Coupling Approach<
The CNC have developed an approach to enable the flexible composition and deployment of coupled applications. This framework has emerged from work with the Met Office (see below) over the last few years and has wide applicability. The approach requires the capturing of component interfaces (description) and provides a dataflow-based composition mechanism to build applications out of components. The description of interfaces allows composition to be done at an abstract level, independent of implementation details associated with particular application codes which satisfy the interfaces. The data flow model places requirements on the application provider in terms of communication mechanisms.
In one possible implementation, application writers simply place "put" and "get" calls in their code to reflect the required communication but, at composition time, the implementation details of the communication are irrelevant. All that is required at composition time is knowledge of the data fields a component "requires" and the data fields it can "provide" to other components.
FCA separates the concerns of composition from deployment issues such as how to configure components to executables and where to deploy the resulting executables. Associated with each phase of this Description, Composition and Deployment (DCD) approach is metadata which captures relevant information from each phase.