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__________________________
_____________________________________________










EA White Paper:

Convergence in Traffic Information

Framework
Models










Mike Williams

Enterprise Architecture Team
EA White Paper:

Convergence in Traffic Inform
ation Framework Models

______________________________________________________________
_______________________

_____________________________________________________________________________________
9
th

June

2010

(v0.
4
)

2

of
14


Table of Contents


Background

................................
................................
................................
................................
...................

3

UTMC

................................
................................
................................
................................
............................

3

DATEX II

................................
................................
................................
................................
.........................

5

Introduction

................................
................................
................................
................................
..............

5

Architecture Framework

................................
................................
................................
...........................

5

Extensibility

................................
................................
................................
................................
...............

8

The Best of both Worlds

................................
................................
................................
.............................

10

UTMC and DATEX II compared
................................
................................
................................
................

10

Benefits

................................
................................
................................
................................
...................

10

The Process of Convergence

................................
................................
................................
.......................

12

Convergence

................................
................................
................................
................................
...............

13

Bibliography

................................
................................
................................
................................
................

14


EA White Paper:

Convergence in Traffic Inform
ation Framework Models

______________________________________________________________
_______________________

_____________________________________________________________________________________
9
th

June

2010

(v0.
4
)

3

of
14

Background


Historically, the Highways Agency has presided over its own proprietary specif
ications for network management
known as the National Motorway Communications System (NMCS). However, in the modern era of Intelligent
Transport Systems (ITS) and Open Systems, this is no longer sustainable.


Launched in 1997, the UTMC programme was the ma
in UK Department for Transport (DfT) initiative for the
development of a more open approach to Intelligent Transport Systems (ITS) in urban areas. Now
it’s becoming
increasingly important to consider the Urban/Inter
-
Urban environment and end
-
to
-
end journey
s.


The UTMC technical specifications were, from the outset, based on Internet Protocol (IP) standards, including the
Simple Network Management Protocol (SNMP) coupled with the Object Management Group (OMG) standards for
distributed computing


CORBA (Comm
on Object Request Broker Architecture). The current specifications use
SNMP for Centre
-
to
-
Device communications and CORBA for Centre
-
to
-
Centre communications.


Whilst the HA is migrating from NMCS to UTMC, projecting increased demands in the future necessi
tates a
new
generation
of standards that go beyond SNMP and CORBA and embrace new technologies & standards such as
Service
-
Oriented Architecture (SOA) and
DATEX

II.


UTMC


UTMC has embraced
I
nternet communications protocols since its original publication i
n 1997, and since 2005 has
permitted

the use of XML structures. Indeed the use of XML in UTMC goes back to the Reading demonstrator
(around 2003), where it was used to collate bus, rail and road information into the Reading Common Database.
However up unti
l 2009 there were no accepted data structures written using XML, so any use of XML within UTMC
systems was necessarily
ad hoc
.


With the recasting of the Objects Registry into
Uni
fied

Modelling Language

(UML) format in the 2008 edition,
however, the way wa
s clear for a holistic transformation of UTMC. During 2009, a number of industry players
collaborated on the production of the utmcXML framework, which covers the whole of the 2008 UML model and
incorporates the work on ANPR that was developed in parallel.

The bulk of the technical work was undertaken by
Kizoom, with funding provided under the Government
-
supported project FREEFLOW, but the XML Working Group
provided extensive input and support.


The structure of the UTMC specifications is illustrated in
Figure
1
.
The Objects Registry
,
UTMC
-
TS004.006:2010

-

presents the data standards recommended for use by UK Traffic Managers in their systems. Details are provided in
normative annexes.

This document
complements
UTMC
-
TS003 03:2009

which is

the main repository of UTMC
techn
ical recommendations
. The UTMC Objects Registry con
sists of the following
:




UTMC
-
TS004.006:2010: Main text and key annexes including MIB definitions
.



Annex D.1 to UTMC
-
TS004.006:2010: UML representat
ion of UTMC data objects
.



Annex D.2 to UTMC
-
TS004.006:2010: AN
PR data objects.



Annex G to UTMC
-
TS004.006:2010: UTMC XML schema for data objects and exchange
.



EA White Paper:

Convergence in Traffic Inform
ation Framework Models

______________________________________________________________
_______________________

_____________________________________________________________________________________
9
th

June

2010

(v0.
4
)

4

of
14


Figure
1

-

UTMC Specifications
(Source: Kizoom)


The UTMC XML Physica
l Model (UML) has not yet been made available in the UTMC specifications; however, there
is a very useful
informal document
-

a


UTMC XML Handbook


which con
tains diagrams from this UML model.


There are two outstanding work items


due to time and funding constraints the following have not been
incorporated into the UML Model:


1.

The ANPR data objects (Annex D.2)


these are contained within a spreadsheet

and a
re under review by
the HA’s ITS Metadata Registry Project
.

2.

Two new FREEFLOW objects: Alerts and Interventions.


The ITS Metadata Registry also has a
separate
draft model registered for the UTMC Roadside MIB’s a
s

shown in
Figure
2

below.


Figure
2

-

UTMC Roadside MIB's


EA White Paper:

Convergence in Traffic Inform
ation Framework Models

______________________________________________________________
_______________________

_____________________________________________________________________________________
9
th

June

2010

(v0.
4
)

5

of
14

DATEX

II

Introduction

DATEX

II was
developed to provide a standardised way of communicating and exchanging

traffi
c information
between traffic centres,

service providers, ot
her road

operators and media

partners. The specificati
on provides for
a harmonised method

for

exchanging data across
organisational
boundaries,

at a system level, to enable better
management of the European road network.

The target

applications

include
:




R
erouting, network management and traffic management planning.



Lane control systems and related applications like ramp metering, dynamic speed limits and overtaking
controls.



Linking traffic management and traffic information systems.



Applications where in
formation exchange between individual vehicles and traffi
c management is crucial,
i.e.

Vehicle
-
to
-
Infrastructure (V2I) systems.



Applications where information exchange between management systems for
different modes is crucial,
i.e.

multi
-
modal information
systems
1
.



Applications where the exchange of measured data is important
.



Provision of services in the framework of
road management with
strong link
s

to network
safety and
performance objectives.


DATEX

II
currently

covers a wide range of

content in the roa
d traffic and transport

domain.
O
ne of
its main
achievements

is the
establish
ment

of
a logical model for this

domain
which

is widely supported all over Europe.
The initiative was
originally
started by

trunk road operators in the past but now has

been exten
ded into the urban
and logistics

domain. The fl
exible approach and the built
-
in

extensibility make it likely that coverage

will extend
even further in the future and that
, as a CEN standard,
DATEX

II will become the leading reference

model for road
transpo
rt in Europe.

The model already covers:




Levels of service on the network, both in terms of messages for specific situations or as an overall status
on the network.



Travel times, both on short network links and long distance travel itineraries.



All types o
f incidents and accidents.



Road works and street works.



Road infrastructure status.



Closures, blockages and obstructions.



Road weather, again as events as well as status/measurements
.



All kinds of traffic related measurements (speed, flow, occupancy, etc…)
.



Public events with impact on traffic
.


Architec
t
ure Framework


One of the main objectives of
DATEX

II
is to be platform independent. It also aims at providing interoperability and
is
therefore as prescriptive as possible.

Nevertheless, it does provide fl
exibility in that the model is fully extensible.

It achieves this through
adoption of the Object Management Group (OMG) Model
-
Driven Architecture (MDA).

Th
is
is based on the following con
cepts:





1

SIRI

is a competing standard in this domain.

The C
EN ITS Standards Technical Committee (CEN/TC278)
will need
to address matters of convergence between formally recognised Stand
ards that include DATEXII and SIRI
.

EA White Paper:

Convergence in Traffic Inform
ation Framework Models

______________________________________________________________
_______________________

_____________________________________________________________________________________
9
th

June

2010

(v0.
4
)

6

of
14

Model

A
model
of a system is a description or specification o
f that system and its

environment for some certain purpose.
A model is often presented as a combination

of drawings and text. The text may be in a modeling language or in a
natural language.


Model
-
Driven

MDA is an approach to system development, which inc
reases the power of models in

that work. It is
model
-
driven
because it provides a means for using models to direct the

course of understanding, design, construction,
deployment, operation, maintenance and

modification.


Platform

A
platform
is a set of subs
ystems and technologies that provide a coherent set of

functionality through interfaces
and specified usage patterns, which any application

supported by that platform can use without concern for the
details of how the

functionality provided by the platform

is implemented.


Platform Independence

Platform independence
is a quality, which a model may exhibit. This is the quality that

the model is independent of
the features of a platform of any particular type.


Platform Independent Viewpoint

The
platform inde
pendent viewpoint
focuses on the operation of a system while hiding

the details necessary for a
particular platform. A platform independent view shows that

part of the complete specification that does not
change from one platform to another.

A platform ind
ependent view may use a general purpose modeling
language, or a

language specific to the area in which the system will be used.


Platform Specific Viewpoint

The
platform specific viewpoint
combines the platform independent viewpoint with an

additional focu
s on the
detail of the use of a specific platform by a system.


Model Transformation

Model transformation
is the process of converting one model to another model of the

same system.

Figure
3

illustrates the MDA pat
tern, by which a PIM is transformed to a PSM.



Figure
3

-

Model
-
Driven Architecture (MDA)



The resulting DATEX II

architecture framework
is
as shown in
Figure
4

below.


EA White Paper:

Convergence in Traffic Inform
ation Framework Models

______________________________________________________________
_______________________

_____________________________________________________________________________________
9
th

June

2010

(v0.
4
)

7

of
14


Figure
4

-

The
DATEX

II Architecture Framework


The
DATEX

II modelling approach is

based on
MDA and
UML which provided the basis for
captur
ing the
domain
model.
Given the many research and development projects that have
been deployed
over the las
t decade it’s

clear
that h
armonising ITS

concepts on
a

European
scale will

take a
relatively
long

time to achieve so
it would be
inappropriate
to capture the results from this effort in a

short
-
lived, technology
-
dependen
t way. U
ML offers the
required stabi
lity, with

a

concrete mapping to exchange artefacts

specified through
the
application of
MDA
principles.

The
current
implementation platform for
DATEX

II
messaging

is the W3C standard for
XML schema

definiti
on
. This

mapping is well defined in the
W3C
speci
fications

and has been implemented in a
Schema
Generation T
ool that

users can download

from
www.
DATEX
2.eu
.

Users

are also able to select those

data elements
for schema generation

which they

actually

require
in their
bus
iness
services. Thus,

slim


services can

still work
with

slim


schemas without having

to carry the full burden of the
whole UML
model.


As the definitions for the data content in
DATEX

II are only stored within the UML

model, which are not
easily
readabl
e
by non
-
IT professionals, a readable data

dictionary is
also
available via a software tool which
automatically extracts the definitions from the UML

model.

Also, t
he CEN Standards for
DATEX II, Parts 1 to 3
contain the

bulk of the data dictionary in a hum
an readable form and are oriented towards being paper
documents.


They will be openly available

(est. 01/2012)
.


Users are able, if they want, to extend the

model according to application
-
specific

needs
.

Use
rs that have created
extensions, such as in the u
rban domain, (e.g. SCOOT)
can submit them in

a d
edicated section on the
DATEX
2

website

where

they can be downloaded by other users
.

EA White Paper:

Convergence in Traffic Inform
ation Framework Models

______________________________________________________________
_______________________

_____________________________________________________________________________________
9
th

June

2010

(v0.
4
)

8

of
14

Extensibility



T
he solution to dealing with the

conflicting requirements

of being prescriptive whilst allowing flexibility

is a
concept of three
layers
2

of interoperability
.


Layer A
is for users that only want to use the full, rich data model that has been agreed and harmonised amongst
all European stakeholders. The model is expressed as a class model

in UML
. It was designed

to be as strict and as
unambiguo
us as possible in the
context of European harmonisation. It is fully specified to an extent that
implementation artefacts can be created automatically from it, and it replaces the former
DATEX

Data Dictionary
as the master
resource for content modelling of traffic and travel related information. Applications that have no
content requirements beyond this model do not need to consider
the wider
interoperability
concerns
.


Layer B
provides a mechan
ism to extend “Layer

A


in an

interoperable way, i.e.
where
user
requirements
for local
applications
are
largely covered by

“Layer

A


but
there are
a few details missing
which

can
be met by

adding the
missing
elements
.
DATEX

II provides the
implementation
rules to apply when
extending

the model, and the tools
to create updated PSM

s
.
DATEX

II ensures that extensions following the rules and using the
DATEX

tools will be
interoperable in the sense that any
“Layer

B


extended
system

will
remain
backward
s
-
compatible with all
“Layer

A


syst
ems, and will also be interoperable


at

“Layer

A




with all other
“Layer

B


extended systems.



Layer C
applies

where the
“Layer

B


rules are too constrained to allow a
complete

model
to be
created for new,
innovative
applications
. In such a situation, a

“Layer

B


extended model may not be suitable but the
DATEX

methodology and tools

are
still
of benefit
. Therefore, a third
“Layer

C


has been incorporated where
by

users can
still

benefit from the
DATEX

framework, but the resulting model can only be used b
y

systems that are aware of
these

extension
s, whilst accepting the fact that

it is not interoperable with standard
“Layer

A


equipment.


The main innovation in this concept is the notion of interoperable extensions, i.e.
“Layer

B

. The principle is
illustr
ated in the following figure for an XML scenario, where the middle (blue) system is a standard,
“Layer

A


system (e.g. COTS software). The systems
to the
left and right extend the sample data (
vehicle
) with their own
specific extensions (for
colour
and
typ
e
). Each of the

clients can plug
-
in,
process
and validate

all messages from all
feeds.
However,

the content of the extension part is only available to clients
that are
aware of these

specific
extension
s
,
as
illustrated
in
Figure
5

by the various levels of detail depicted on the three
system screens
.





2

Also referred to synonymously in some DATEX

II documentation as “levels”.

EA White Paper:

Convergence in Traffic Inform
ation Framework Models

______________________________________________________________
_______________________

_____________________________________________________________________________________
9
th

June

2010

(v0.
4
)

9

of
14


Figure
5

-

Extensions and Interoperability


The flexibility and extensibility

of the
DATEX

II Framework also lies in the Technical Architectu
re as well as the Data
Architecture. This stems from the MDA approach which provides

the capability to generate multiple PSM’s from a
single PIM. Whilst the
current
DATEX

II Data Exchange PSM is based on

HTTP


a simple “GET” or

Web Services
(SOAP over HTT
P)
-

and would be used for external, cross
-
border data interchanges
,

o
ther

domains such as those
internal to a particular road operator may use
alternative
integration platforms
, patterns

and protocols such as
Java Message Service (JMS) or Data Distributio
n Service (DDS). This is illustrated in
Fig
ure
6

which depicts multiple
protocols in an Enterprise Service Bus (ESB) based on
an example deployment with
the Open Source

Camel


integration engine and router.



Fig
ure
6

-

Multiple PSM's in Practice

EA White Paper:

Convergence in Traffic Inform
ation Framework Models

______________________________________________________________
_______________________

_____________________________________________________________________________________
9
th

June

2010

(v0.
4
)

10

of
14


The Best of both Worlds

UTMC and DATEX II compared


UTMC and
DATEX

II are compared and contrasted in
Table
1



the proposed iUTMC approach

for the To
-
Be
Architecture

takes
forward
the best of both worlds.


Feature

UTMC

DATEX

II

Proposed
iUTMC

Design emphasis

Interoperability within
Road Operator’s own
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and

Inter
-
Urban
domains

across
organisational boundaries
.

Modelling methodology

Mixture of MDA and
Informal/
Ad hoc

M
DA

MDA

XML Schema generation

Manual

Automatic

Automatic

Standardisation

Supervised but
Permissive

Prescriptive + Extensions

Prescriptive + Extensions

Schema structure

Separately managed sub
-
schemas

One large schema

Separately managed sub
-
schemas

Architectural style

IDL;
point integrations

Web Service Gateway
;
point integrations

Service
-
Oriented (SOA);

Enterprise Service Bus
(ESB)

Platforms,
Protocols

and
Data Exchange
mechanisms

SNMP

CORBA

Web Service
-

XML/HTTP

SIRI

WS

DATEX

II
Web Service
DATEX II
HTTP

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Table
1



UTMC and
DATEX

II Comparisons

Benefits


The benefits of the proposed approach are:


1.

Continues the evolutionary philosophy of the UTMC
Framework.

2.

Builds on existing UTMC standards.

3.

Places an emphasis on the Target (To
-
Be) Architecture as a means of overcoming the constraints of the
Legacy (As
-
Is) Architecture.

4.

Notwithstanding the considerable overlaps, p
rovides
the basis for the developme
nt of
a Roadmap for
existing
DATEX II V1.0 and
UTMC
-
based systems.

5.

Facilitates cross
-
fertilisation between the UTMC and DATEX II communities.

6.

Enables UTMC to add value to DATEX II through the definition of model extensions in the urban transport
domain inc
luding public transport.

7.

Enables UTMC to help extend DATEX II

in a direction where others in Europe also have a significant
interest. This in turn will help UTMC in the long
-
term.

EA White Paper:

Convergence in Traffic Inform
ation Framework Models

______________________________________________________________
_______________________

_____________________________________________________________________________________
9
th

June

2010

(v0.
4
)

11

of
14

8.

Provides a UK Intercept Strategy for the planned European ITS Directive and

CEN standards.

9.

Provides a basis upon which the HA stewardship
and funding
of UTMC can be
strategically
directed.

10.

Recognises the need for diversity and realities of technology churn in the long
-
term.

11.

Exploits the flexibility and extensibility of the
MDA
-
ba
sed DATEX II
framework.

12.

Doesn’t mandate XML


allows for other PSM’s
based on

non
-
XML
payloads

such as V2I

(Vehicle
-
to
-
Infrastructure)

using
the
CAL
M (
Communication Access for Land Mobiles
)
message set
.

13.

Provides
a heterogeneous architecture
, through PSM’s,

which
can be
:



Multi
-
vendor,



Multi
-
service provider,



Multi
-
channel,



Multi
-
protocol,



Multi
-
device,



Multi
-
pattern,
and



Multi
-
platform.


EA White Paper:

Convergence in Traffic Inform
ation Framework Models

______________________________________________________________
_______________________

_____________________________________________________________________________________
9
th

June

2010

(v0.
4
)

12

of
14

The Process of
Convergence


In order t
o achieve the
convergence of data definitions across different systems
required

for

interoperability and
reuse
,

a

process
of “h
armonisation"
is employed
. Harmonisation is an important function of a
metadata registry
process

and
one

that is essential if the most

benefits are to be achieved. The
principal

method used in the
HA’s
ITS
Metada
ta Registry is the technique of "
core components analysis
".


"Core Components" is a UN/CEFACT specification used in e
-
business
(
ebXML
)

standardisation. The key concept

that supports harmonisation is the separation of "core components", which have no speci
fic business context,
from the actual representations used in e
-
business systems for sp
ecific purposes. In terms of the ITS Metadata

R
egistry, the registered models all have their individual business contexts, and they can be seen as context
-
specific
insta
nces of a single set of underlying core components. A simple example is shown

in
Figure
7

below.


Figure
7

-

Example of Core Component Analysis



UML dependencies
are used
to show the association between registere
d items and core components, whilst

the
documentation for each dependency explains the business context and the justification for any difference
s
between the registered items and their corresponding core components. In some cases of particular importance
,

the dependency
is

annotate
d

with a statement that explains the
precise mapping

between the registered item and
the core component

as shown
in
Figure
8
.



EA White Paper:

Convergence in Traffic Inform
ation Framework Models

______________________________________________________________
_______________________

_____________________________________________________________________________________
9
th

June

2010

(v0.
4
)

13

of
14


Figure
8

-

Example of a Precise Mapping


Convergence


For the proposed

iUTMC Framework, a possible approach

for the convergence of UTMC and
DATEX

data models is

depicted in

Figure
9

below.



Figure
9

-

UTMC and
DATEX

Data Model Convergence



i啔MC


EA White Paper:

Convergence in Traffic Inform
ation Framework Models

______________________________________________________________
_______________________

_____________________________________________________________________________________
9
th

June

2010

(v0.
4
)

14

of
14

Bibliography


“Coordinated Traffic Management through Data Exchange”, A.Raines and P. Rowley

DATEX

II


the key t
o successful information exchange

DATEX

II V2.0 User Guide v1.1

DATEX

II V2.0 Modelling Methodology v1.2

MDA Guide Version 1.0.1

UTMC XML & FREEFLOW Part II: “Taking UTMC data to a wider world”, N. Knowles, Kizoom

UTMC XML Handbook v0.08, Kizoom

XML in UTM
C Systems: An Introduction (TR008.001a)

http://www.
DATEX
2.eu/

http://www.kizoom.com/standards/utmc

http://www.itsregistry.
org/

http://www.utmc.uk.com/



<END>