1.2.3 Element interfaces

Each layer of the system is an independent component and can be run in a different environment than the others. The only connection points are the data access layers. The only connection points are the data access layers which are used by two layers in a time. The only interface or contract between the two layers is the underlying data model, which gets written or read by each one of the systems. For example the data layer writes data and the business layer reads the data, both have the only contract which is the data model stored in the database the layers use. They layers itself don’t know each other, only the data access layer knows them both.

1.2.4 Element behaviour

In this subsection we give a high level representation of how a possible communication flow between components, which indicates system behaviour, could be realised. Each layer has its own communication flow and is started independently by a certain event. In case of the Data and Business Logic layer, this is a scheduler. In case of the Representation layer, this is a query fired by the user.

We therefore decided to create 3 UML sequence diagrams in order to depict the communication flow within each component in each layer. We are using a more loose representation of this diagram, as we do not want to go into too much technical detail within the logical and implementation view. This diagram should therefore also be understandable for non-technical stakeholders.

Data Layer:

Business Logic Layer:

Modifying business rules:

Transforming data:

Representation Layer: