Multi-level Abstraction Techniques– A Practical Application PerspectiveMarch 2014

Presentation summary on the work inNeumayr, B., Schrefl, M., & Thalheim, B. (2011). Modeling techniques for multi-level abstraction. The Evolution of Conceptual Modeling, 68–92.

Motivation• To reduce accidental complexity of domain models occurring

due to mismatches between a problem and the technology used to represent the problem

• Domain models are increasingly required to support perspectives at different levels of abstraction

• Is there a modelling technique that can reduce complexity while supporting multi-level abstraction?

Introduction

Evaluate multi-level abstraction techniques:– Powertypes (Cardelli)– Deep Instantiation (Atkinson and Kühne)– Materialisation (Pirotte)– M-Objects (Neumayr, B. et al)– HERM (Thalheim, B.)– Component Model (Thalheim, B.)

Evaluation Criteria• Compactness: A domain model is compact if it is modular and

redundancy-free. • Query flexibility: A domain model supports query flexibility if it

provides several pre-defined entry points for querying, such as class names or qualified identifiers to refer to various sets of objects.

• Heterogeneous level-hierarchies: Whether additional abstraction levels can be inserted without affecting the abstraction levels of other domain concepts

• Multiple relationship-abstractions: supports multi-level abstraction of relationships

Multi-Level Abstraction Techniques

Deep Instantiation Refers to meta modelling in which an object at some (meta-)level can describe the common properties for objects at each instantiation-level beneath that level.

Multi-Level Abstraction Techniques

PowertypesA powertype has subclasses of a given class as its instances and allows to describe common properties of these subclasses

Simple pattern

Extended pattern

Multi-Level Abstraction Techniques

Materialization Relates a class of categories (e.g. car models) and a class of more concrete objects (e.g. physical cars)

Multi-Level Abstraction Techniques

M-Objects A multi-level object (m-object) encapsulates the different levels of abstractions that relate to a single domain concept; a multi-level relationship (m-relationship) links two m-objects at multiple levels

Multi-Level Abstraction Techniques

HERM (Higher-order Entity Relationship Model)Extends the classical entity- relationship model by complex attributes, relationship types of higher order, and cluster types.

Overlay schema

Specialisation schema

Multi-Level Abstraction Techniques

Component ModelEnhances the HERM by encapsulation based on component schemata. Components may have various ports and views for exchange. Ports are associated through harnesses.

Multi-Level Abstraction TechniquesResults Compactness Query

FlexibilityHeterogeneous Levels

Relationship Abstraction

Deep Instantiation

Full Full No support Partial

Powertypes (Simple)

Partial Partial No support Partial support using OCL

Powertypes (Extended)

Partial Full Full Partial support using OCL

Materialisation Full Partial No support Partial

M-Objects Full Full Full FullHERM Partial Full with

Overlay Schema

Full with Specialisation Schema

Partial

Component Model

Partial Partial Full Full

Multi-Level Abstraction Techniques

DiscussionWhich criteria are most important to us?

– Heterogeneous Levels– Relationship Abstraction– Query Flexibility– Compactness

Which approach satisfies minimum requirements for modelling abstraction levels of ISO 15926 data model?