Page 106 - DCAP603_DATAWARE_HOUSING_AND_DATAMINING

Data Warehousing and Data Mining

notes counterpart which provides specific details over the actual components that execute the activity
and the conceptual perspective which abstractly represents the basic interrelationships between
data warehouse stakeholders and processes in a formal way.

figure 5.2: the reasoning behind the 3 perspectives of the process Metamodel

Typically, the information about how a process is executed concerns stakeholders who are
involved in the everyday use of the process. The information about the structure of the process
concern stakeholders that manage it and the information relevant to the reasons behind this
structure concern process engineers who are involved in the monitoring or evolution of the
process environment. In the case of data warehouses it is expected that all these roles are covered
by the data warehouse administration team, although one could also envision different schemes.
Another important issue shown in Figure 5.2 is that there is also a data flow at each of the
perspectives: a type description of the incoming and outcoming data at the logical level, where
the process acts as an input/output function, a physical description of the details of the physical
execution for the data involved in the activity and a relationship to the conceptual entities related
to these data, connected through a corresponding role.
Once again, we have implemented the process metamodel in the Telos language and specifically
in the ConceptBase metadata repository. The implementation of the process metamodel in
ConceptBase is straightforward, thus we choose to follow an informal, bird’s-eye view of the
model, for reasons of presentation and lack of space. Wherever definitions, constraints, or queries
of ConceptBase are used in the chapter, they will be explained properly in natural language,
too.
In the sequel, when we present the entities of the metamodel, this will be done in the context of a
specific perspective. In the Telos implementation of the metamodel, this is captured by specializing
the generic classes ConceptualObject, LogicalObject and PhysicalObject with ISA relationships,
accordingly. We will start the presentation of the metamodel from the logical perspective. First,
we will show how it deals with the requirements of structure complexity and capturing of data
semantics in the next two sections. In the former, the requirement of trace logging will be fulfilled
too. The full metamodel is presented in Figure 5.3.

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