GENERAL OVERVIEW
The ACTIF model describes
the business model reference architecture for the field of Intelligent
Transport Systems. The "Browsing the model" section of ACTIF Website
provides access to various components of the model. The purpose of this page is
to define all the terms and concepts necessary for understanding, browsing and
using the model.
ACTIF concepts
Figure 1 lists the concepts presented under
the various headings below :
Click on a concept to reach its definition in this page
Figure 1 : Major components of the ACTIF model
Terminators
Terminators represent the
points at which ITS interact with their environment. In the present document we
examine their roles and the consequences of the execution of these roles, which
take the form of data flow exchanges. Their internal functioning (notion of a
“black box”) will not be dealt with.
A terminator is not entity
as such, but rather the representation of the role that it plays: for example
the same person could be regarded as a passenger, driver, or cyclist according
to the role that he/she plays in relation to the system.
Terminators are divided
into 4 types:
·
physical
entities: environment, road surface, …
·
human
entities: operator, driver, passenger…
·
systems:
emergency systems, atmospheric condition systems,…
·
organizations:
transport authorities, financial institutions,…
A terminator is not a true
entity, but it represents a role devoted to it : a same person is to be seen
either as a traveller or adriver or a cyclist.
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Logical
views
Logical views are made up of functional elements that
interact by dataflow exchange. These particular representations of the ACTIF
model define the functions that fulfil the ITS user needs (formalised or not)
and that are satisfied by the ITS.
The functional representation of the ACTIF model is
provided through a hierarchical breakdown of the various functions.They group
together functions. The highest level, in hierarchical terms, is made up
of Functional
Areas, comprising functions which can
themselves be further broken down into key functions,
Logical views represent :
·
The Functions being realised by ITS and
fulfilling user needs;
·
Exchange
of information between these functions (logical dataflows);
·
elements
of information to be archived or put at disposal of the users (datastores).
Figure 2 : Hierarchical breakdown of Functional Area
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Functional
areas
Functional areas group
together functional elements that describe ITS activities. They constitute a
homogeneous and commonly recognized breakdown of the different IT professions /
areas of activity and form the first level of the hierarchical breakdown of
ITS.
The ACTIF architecture is
designed to create / analyse ITS architectures in the following 9 functional
areas:
1.
Provide
Electronic Payment Facilities
2.
Manage
Safety and Emergency Services
3.
Manage
Traffic and Travel
4.
Manage
Public Transport Operations
5.
Provide
Advanced Driver Assistance Systems
6.
Manage
and inform on transportation coordination
7.
Enforce
regulations
8.
Manage
Freight and Fleet Operations
9.
Manage
shared data
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Functions
A
function is an information processing operation. Functions originate from the
hierarchical breakdown of the functional areas represented in logical
(functional) views. A distinction is made between the low level functions and
the high level functions that make up this hierarchical structure.
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Logical
dataflows
A
functional dataflow represents data exchange between different elements of the
model: function, terminator, datastore.
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Datastores
They represent the
elements that are designed to conserve and provide information processed in an
ITS. They are linked to a functional area and are situated at different levels
within the breakdown of this area.
They are made up either of
permanent data, intended for archiving or information consultation, or of
temporary data used for the deferred processing of “real time” information.
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Logical views are based on 3 types of diagrams:
·
a
general "Context diagram", registering the whole set of Terminators;
·
Functional
trees - see Figure 3 below;
·
DataFlows
Diagrams (DFD) - see Figure 4 below.
Figure 3 : Functional tree
Figure 4 : example of a DFD
Thematic views
Thematic views illustrate
a process, a transaction or part of a transaction implementing the elements of
the ACTIF model. Thematic views group together elements that would not be
represented together on a logical view or a package view, for example functions
and physical sub-systems or functions from different functional areas. In this
respect they differ from the other types of view that focus on the hierarchical
and structured nature of the model.
These views have several
uses:
·
they
enable a process to be visualised “from start to finish”: it is therefore
possible to show the manner in which information is processed by functions of
different functional areas and different levels, within a specific context
(functional area studies).
·
they
highlight the interfaces between two different parts of the model.
·
they
enable a system designer to focus on a particular part of the model.
They cover all of
the architecture modelled. They may just as easily contain elements from a
package (physical) view as from a logical (functional) view.
Figure 8 : Example of a thematic view
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