Terminology Jargon Buster
A lot of people seem to use terms like Taxonomy and Ontology in a variety of different ways. These terms all have standard definitions in academia, particularly in the field of artificial intelligence. The way these terms are used on this site and in all our work conforms to the best available definitions. These are summarised on this page.
The terms used here relate to the modelling of business semantics - known as the Business Domain or in artificial intelligence as the Problem Domain. There are two aspects of the problem domain that may be modelled:
- Structural: The static or data requirements
- Behavioural: The dynamic behaviour of the problem domain, i.e. business processes
The terms used to describe various ways of modelling these are as follows:
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Structural models of the business domain deal with the business equivalent of data: the business terms, definitions and relationships that may be reflected in systems, messages and databases. This is often referred to generically as "ontology" or "taxonomy" modelling.
A taxonomy is a hierarchical tree structure. It models hierarchical relationships between terms in the domain, with the most general at the top and the most specific at the bottom. A good example is the Linnaean taxonomy of species.
A thesaurus is a structured vocabulary that defines each term by 3 kinds of relationship: hierarchical (as in a taxonomy), associative and equivalent. As such this is probably closer to what many in the financial industry refer to as a Taxonomy.
The best available definition from academia is that an ontology is a model which has:
- Formal explicit description of concepts in a domain of discourse (referred to as Classes)
- Properties of each concept (class) describing features and attributes (known variously as slots, properties or roles)
- Restrictions on those properties (known as facets).
An ontology plus an instance of information modelled according to that ontology constitutes a knowledge base.
The Semantic Web uses the OWL ontology language. This refers to properties of classes as "Properties" rather than "Slots", the term used in earlier ontology formats.
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(from Schwartz, 2005)
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A data dictionary consists of a set of data plus verbal definitions of terms within a list or formal structure. These are intended to be human readable and add nothing to the machine processing of terms. It is possible to give dictionary definitions against data items in a structured format such as an XML schema or a UMLTM data model. A Data dictionary can also be included within a taxonomy or an ontology. Note that ontology tools provide for formal written definitions to enhance the ontological structures within them.
Behavioural models may describe one or more of the following dynamic aspects of the business domain:
There are numerous notations for modelling business processes. Some of these are understandable to business people while others are intended for more formal modelling of the process in a machine-processable way. In recent years there has been considerable development of standard notations for business process modelling, and this is what will be described here.
A challenge in many of the modelling formats is to be able to produce outputs that can be comprehended by business people, while maintaining the integrity of the formal definitions of process requirements. reviewable outputs from these models would need to be in the formats which are well known and widely used by industry participants, such as:
- Process Flow diagrams
- "Doric column" message sequence diagrams.
Note that "Doric column" diagrams can be directly derived from UMLTM Message Sequence diagrams, one of the recognised model formats within UMLTM. Process flow diagrams are well known but are not supported in existing formal UMLTM notation, however the Enterprise Architect UMLTM tool has extensions to support these.
This can be described as:
- The behaviour of a business process based on interactions between the process and its partners;
- how multiple service interactions with these partners are coordinated to achieve a business goal;
- the state and the logic necessary for this coordination;
- mechanisms for dealing with business exceptions and processing faults;
- a mechanism to define how individual or composite activities within a process are to be compensated in cases where exceptions occur or a partner requests reversal.
(based on the WS-BPEL standard definition)
Choreography relates to the exchange of messages between actors in a process. These may be a drinks machine and the person buying a drink, or they may be the counterparties in a financial instrument transaction.
Within recent standards-based work, choreography has been approached in two different ways:
- Pi Calculus
- The ebXML Business Process Specification Schema
The latter covers features relating to business process modelling as a whole.
According to the W3C, "choreography" can be defined as:
"... the ability to compose and describe the relationships between lower-level services. Although differing terminology is used in the industry, such as orchestration, collaboration, coordination, conversations, etc., the terms all share a common characteristic of describing linkages and usage patterns between Web services. ... we use the term choreography as a label to denote this space.
Reference: Web Services Choreography Working Group Charter.