04 H2 for Reporting & H2-Toolset

Question 1

Why Conceptual models (are used)?

Answer 1

Conceptual models:

• Serve as a communication basis between business and IT
• Promote understanding and spreading of the domain (MIS & DWH)
• Serve as a basis for technical models and/or final implementation
• Serve as long-term documentations

Question 2

What aspects are covered by a Conceptual modeling language? (and H2)

Answer 2

• Ratios (measures)
• Ratio systems
• Dimensions
• Hierarchies
• Reference Objects
• Cubes
• Reports

Question 3

What is the normal modeling order approach?

Answer 3

1. Define Dimensions and their Reference Objects
2. Build Dimension Scopes
3. Define Ratios (and maybe Fact Calculations)
4. Assemble ratio systems
5. Define Cubes
6. Build Reports based on Cubes

Question 4

Graphically identify which meta-model elements are depicted as symbols in H2:

Answer 4

Meta-model elements that are present as symbols in H2:

• Row
• Column
• Report
• Filter
• Cube (navigation space)
• Ratio System [R]
• Fact Calculation [F]
• Dimension scope [<>]
• Dimension [D]
• Instance object [I] <– from Reference object
• Selection object [S] <– from Reference object

Question 5

When does it make sense to modell all instance objects?

(and when not?)

Answer 5

Doesn’t make sense to model all of them because:

• There are too many (time dimension, products)
• It is obvious (time dimension, countries)
• We don’t know them (customers, products)

… but it makes sense when:

• To give examples (product categories, customer types)
• To clarify things (granularity needed: territory, area, region…)
• In case of a small set (predefined/fixed objects, as-is vs to-be)