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An internet-based logistics management
system for enterprise chains
N. Prindezis, C.T. Kiranoudis
School of Chemical Engineering,
National Technical University, 15780 Athens,
Greece
Received 13 September
2003; received in revised form 20 December 2003;
accepted
27 January 2004
Available online 10 December 2004
.Developing the internet-based
application tool
Web
services
offer
new
opportunities
in
business
landscape,
facilitating
a
global
marketplace
where
business
rapidly
create
innovative
products
and
serve
customers
better. Whatever that business needs
is, Web services have the flexibility to meet the
demand
and
allow
to
accelerate
outsourcing.
In
turn,
the
developer
can
focus
on
building
core
competencies
to
create
customer
and
shareholder
value.
Application
development is
also more efficient because existing Web services,
regardless of where
they were
developed, can easily be reused.
Many
of
the
technology
requirements
for
Web
services
exist
today,
such
as
open
standards
for business to-business applications, mission-
critical transaction platforms
and
secure
integration
and
messaging
products.
However,
to
enable
robust
and
dynamic integration of
applications, the industry standards and tools
that extend the
capabilities of to days
business-to-business interoperability are
required. The key to
taking full
advantage of Web services is to understand what
Web services are and how
the
market
is
likely
to
evolve.
One
needs
to
be
able
to
invest
in
platforms
and
applications
today
that
will
enable
the
developer
to
quickly
and
effectively
realize
these benefits as well as to be able to
meet the specific needs and increase business
productivity.
Typically,
there
are
two
basic
technologies
to
be
implemented
when
dealing
with
internet-based applications; namely
server-based and client-based. Both technologies
have
their
strong
points
regarding
development
of
the
code
and
the
facilities
they
provide.
Server-based
applications
involve
the
development
of
dynamically
created
web pages. These pages are transmitted
to the web browser of the client and contain
code in the form of HTML and
JA
V
ASCRIPT language. The
HTML part is the static
part of the
page that contains forms and controls for user
needs and the JA
V
ASCRIPT
part
is
the
dynamic
part
of
the
page.
Typically,
the
structure
of
the
code
can
be
completely changed through the
intervention of web server mechanisms added on the
transmission part and implemented by
server-based languages such as ASP, JSP, PHP,
etc. This comes to the development of
an integrated dynamic page application where
user desire regarding problem
peculiarities (calculating shortest paths, execute
routing
algorithms, transact with the
database, etc.) is implemented by appropriately
invoking
different parts of the dynamic
content of such pages. In server-based
applications all
calculations
are
executed
on
the
server.
In
client-based
applications,
JA
V
A
applets
prevail.
Communication
of
the
user
is
guaranteed
by
the
well-known
JA
V
A
mechanism that acts as the medium
between the user and code.
Everything
is executed on the client side. Data in this case
have to be retrieved, once
and this
might be the time-consuming part of the
transaction.
In
server-based
applications,
server
resources
are
used
for
all
calculations
and
this
requires powerful
server facilities with respect to hardware and
software. Client-based
applications
are
burdened
with
data
transmission
(chiefly
related
to
road
network
data).
There
is
a
remedy
to
that;
namely
caching.
Once
loaded,
they
are
left
in
the
cache archives of the web browser to be
instantly recalled when needed.
In
our
case,
a
client-based
application
was
developed.
The
main
reason
was
the
demand
from
the
users
point
of
view
for
personal
data
discretion
regarding
their
clients.
In
fact, this information was kept secret
in our system even from the server
side involved.
Data
management
plays
major
role
in
the
good
function
of
our
system.
This
role
becomes
more substantial when the distribution takes place
within a large and detailed
road
network like this of a major complex city. More
specifically, in order to produce
the
proposed the routing plan, the system uses
information about:
?
the locations of the depot and the
customers within the road network of the city
(their co-ordinates attached in the map
of the city),
?
the demand of the customers serviced,
?
the capacity of
the vehicles used,
?
the spatial characteristics of road
segments of the net work examined,
?
the topography
of the road network,
?
the speed of the vehicle, considering
the spatial characteristics of the road and the
area within of which is moved,
?
the synthesis
of the company fleet of vehicles.
Consequently, the system combines, in
real time, the available spatial characteristics
with
all
other
information
mentioned
above,
and
tools
for
modelling,
spatial,
non-spatial,
and statistical
analysis,
image processing forming a scalable, extensible
and interoperable application
environment.
The
validation
and
verification
of
addresses
of
customers
ensure
the
accurate
estimation of travel times and
distances travelled. In the case of boundary in
the total
route duration,
underestimates of travel time may lead to failure
of the programmed
routing plan whereas
overestimates can lower the utilization of drivers
and
vehicles,
and
create
unproductive
wait
times
as
well
(Assad,
1991).
The
data
corresponding to the area of interest
involved two different details. A more detailed
network,
appropriately
for
geocoding
(approximately
250,000
links)
and
a
less
detailed for routing
(about 10,000 links). The two networks overlapped
exactly. The
tool that provides
solutions to problems of effectively determining
the shortest path,
expressed in terms
of travel time or distance travelled, within a
specific road network,
using the
Dijkstra
’
s
algorithm(Winston,1993). In particular, the
Dijkstra
’
s algorithm is
used in two cases during the process of
developing the routing plan. In the first case, it
calculates the travel times between all
possible pairs of depot and customers so that
the
optimizer
would
generate
the
vehicle
routes
connecting
them
and
in the
second
case it determines
the shortest path between two involved nodes
(depot or customer)
in
the
routing plan, as
this
was determined by the algorithm
previously. Due to the
fact,
that
U-turn
and
left-,right-turn
restrictions
were
taken
into
consideration
for
network junctions, an arc-based variant
of the algorithm was taken into consideration
(Jiang, Han, & Chen, 2002).
The system uses the optimization
algorithms mentioned in the following part in
order
to automatically generate the set
of vehicle routes (which vehicles should deliver
to
which customers and in which order)
minimizing simultaneously the vehicle costs and
the total distance travelled by the
vehicles This process involves activities that
tend to
be more strategic and less
structured than operational procedures. The system
helps
planners and managers to view
information in new way and examine issues such as:
?
the
average cost per vehicle, and route,
?
the vehicle and
capacity utilization,
?
the service level and cost,
?
the
modification
of
the
existing
routing
scenario
by
adding
or
subtracting
customers.
In order to support the
above activities, the interface of the proposed
system provides
a variety of analyzed
geographic and tabulated data capabilities.
Moreover, the system
can
graphically
represent
each
vehicle
route
separately,
cutting
it
o?
from
the
final
routing plan and offering the user the
capability for perceiving the road network and
the locations of depot and customers
with all details.