What is an information model?
Terms
Reality What surrounds us. Physics, mathematics and philosophy attempt to describe it.
Individual reality What we perceive as reality as individuals. How we interpret it, how we use it for ourselves.
Collective reality What we as a group of individuals find relevant for our communication and cooperation. In collective reality, we name, understand and use things by consensus.
Sphere of Influence(1) The world in which an information model functions as a documentation of collective reality. This world is any environment (company, industry, scientific discipline, association, sport, authority, etc.) that communicates with each other in some form as a community and wants to achieve something together.
(1) The term ‘sphere of influence’ was defined in the meaning used here by Christian Bühlmann and Stefan Berner.
Information Model
An information model describes the relevant things (entities), their properties (attributes) and relationships in its target environment (sphere of influence). It defines the names to be used in communication, together with their meaning and purpose in this environment.
The following definitions are all represented graphically as information model excerpts. The complete information model can be found here.
The information model documents only the naming and meaning of things in the real world. It does not contain any information about the presentation (user interfaces), technical implementation (databases, applications) or use (processes) of this information.
The information model does not contain any concrete statements (values) about the real world. (Apart from examples to aid understanding of the meaning.)
Example:
Stefan Berner lives in Bern.
is a concrete, value-laden statement about the predicate in the information model Person lives in city.
Concrete statements are typically managed in databases and IT systems that implement the corresponding information model. For this management of knowledge in the form of data, the information model provides the exact description of the information requirements. The information model documents the structure of all possible true statements that are relevant in this real world. This description represents the desired interpretation of the data values. It turns data into usable information in the first place.
Thanks to its mathematical basis (relational model), it provides a verifiable model that describes the structure of all possible true statements (facts/predicates in the sense of predicate logic) for the target environment. The information model is redundancy-free, i.e. minimal. No statement may be included multiple times in the model, either directly or indirectly.
Example:
From the documented statements:
A person lives in a city.
A city is located in a country.
it follows that
a person lives in a country.
Documenting this last statement would therefore be redundant.
CORE MODEL
The core model comprises the minimum elements that make up an information model. In theory, these elements are sufficient to describe an information model in its entirety.
The core model is based on the relational model and requires, in particular, that the three normal forms of the relational model be adhered to.
The elements of the core model are entity, attribute, relationship, value range, key, exclusive relationship, consistency rules, business rulessmodell
Extended model
For practical purposes, there are extensions to the core model. They serve to make the information model easier to read and maintain.
Although some appear to violate the rules of the core model, they are defined in such a way that their equivalent representation in the core model can be achieved automatically.
Elements in the extended model are many-to-many relationships, roles, categories, multivalued attributes, attribute groups,
Model Management
A model requires meta-information that goes beyond the definition of content aspects.
What are the sources of the information? Who is responsible for the technical definition? Who changed what and when? How should elements be displayed? etc.