Digital library and Distance Learning Web service based Middleware: Specifications and Applications

Abstract

Efforts for next generation digital library and e-learning architectures are aiming for a transition from these systems as integrated, centrally controlled systems to dynamic configurable federation of library and educational services and information collections. So, developers adapt their systems to novel technology trends and developments including technologies like Web services and the grid as well as the success of new paradigms like peer-to-peer networking; and also, service oriented architectures. Systems have major drawbacks because of their limitations in scalability, availability, distribution of computing power and storage system, as well as sharing information between users that contribute in these systems. Proposing a grid DLEL middleware, we described how some new technologies including agent, Web service and grid and emerging standards can be applied to digital library and e-learning

Full text

Digital
library
and
Distance
Learning
Web
service
based
Middleware:
Specifi'cations
and
Applications
Hajar
Kashfi
hkashfi(dce.
aut.
ac.
ir
CEIT
Department
Islamic
Azad
University
of
Qazvin
Qazvin,Iran
Abstract
Current
efforts
for
next
generation
Digital
library
and
e-learning
architectures
are
aiming
for
a
transition
from
these
systems
as
integrated,
centrally
controlled
systems
to
dynamic
configurable
federation
of
library
and
educational
services
and
information
collections.
So,
developers
adapt
their
systems
to
novel technology
trends
and
developments
including
technologies
like
Web
services
and
the
Grid
as
well
as
the
success
of
new
paradigms
like
Peer-to-Peer
networking;
and
also,
Service
oriented
Architectures.
Current
systems
have
major
drawbacks
because
of
their
limitations
in
scalability,
availability,
distribution
of
computing
power
and
storage
system,
as
well
as
sharing
information
between
users
that
contribute
in
these
systems.
Proposing
a
grid
DLEL
middleware
,we
described
how
some
new
technologies
including
agent,
web
service
and
Grid
and
emerging
standards
can
be
applied
to
Digital
library
and
E-learning.
l.Introduction
One
of
the
main
objectives
of
digital
library
and
e-
learning
systems
is
to
make
information
accessible
for
any
type
of
users.
A
digital
library(DL)
is
a
distributed
technology
environment
which
dramatically
reduces
barriers
to
the
creation,
dissemination,
manipulation,
storage,
integration,
and
reuse
of
information
by
individuals
and
groups[l].on
the
other
hand
,E-learning
(EL)
could
be
regarded
as
the
process
of
learning
with
the
use
of
Telematics
that
is
the
combination
of
telecommunication,
information
and
multimedia
technology
and
its
services
[2].
Both
Digital
Library
and
E-Learning
systems
have
been
topics
of
increasing
interest
in
recent
years.
Users
who
are
interested
in
such
systems
are
daily
increase.
These
users
have
many
different
interests
and
objectives
and
they
will
need
to
access
to
a
huge
amount
of
information.
Therefore,
a
Mohammda
Reza
Razzazi
razzazi@,ce.
aut.
ac.
ir
CEIT
Department
Amirkabir
University
of
technology
Tehran,Iran
successful
system
will
be
one
that
addresses
all
these
issues
for
all
type
of
users
across
the
world.
Such
a
system
should
be
scalable,
available,
interoperable,
extensible,
and
adaptable
and
indeed
it
should
be
based
on
novel
technologies.
Since
such
systems
are
very
huge,
many
organizations
and
institutes
can
contribute
in
the
construction
of
these
systems
[3].
So
the
development
costs
of
these
systems
will
highly
decrease.
These
organizations
can
cooperate
under
some
policies
to
reach
their
common
objectives.
Here,
we
need
a
middleware
for
uniform
access
to
all
theses
resources
belonging
to
different
administration
areas.
Also,
an
infrastructure
is
needed
that
insure
availability,
scalability,
security,
extensibility
and
interoperability
for
implementing
such
distributed
systems.
Each
organization
should
be
able
to
reuse
functionalities
and
services
as
well
other
resources
that
are
provided
by
other
organizations.
This
paper
reports
the
efforts
that
have
been
done
to
develop
an
DLEL
grid
middleware.
By
proposing
the
use
of
grid
technology
as
scalable,
flexible,
coordinated
and
secure
resource
sharing
among
geographically
distributed
individuals
and
institutions
[4]
in
the
context
of
e-learning,
we
are
able
to
address
interoperability,
distribution
and
sharing
concerns.
Our
middleware
focused
on
Grid
as
well
as
using
agent
[5]
and
web
service
[6]
technologies
to
provide
developers
an
integrated
infrastructure
facilitating
digital
library(DL)
and
E-learning(EL)
system
development.
Meanwhile,
by
implementing
our
middleware
based
on
web
service
technology,
we
are
able
to
reuse
functionalities.
This
way,
many
service
providers
and
content
providers
can
contribute
in
developing
a
very
large
scale
integrated
e-learning
system.
The
reminder
of
this
paper
is
structured
as
in
the
following:
section
2
gives
some
background
information
in
Grid
technology,
section
3
describes
web
services.
In
section
3,
there
is
some
information
in
the
field
of
web
services.
In
section
4
next
generation
digital
library
and
e-learning
have
been
introduced.
In
section
5
the
convergence
of
grid
,digital
library
0-7803-9521-2/06/$20.00
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631

and
e-learning
systems
are
discussed.
In
section
6
Digital
library
and
e-learning
standards
and
specifications
are
exposed.
Section
7
discusses
our
proposed
middleware
architecture,
and
finally,
section
8
contains
the
conclusion.
2.Grid
Technology
Grid
is
coordinate
resource
sharing
and
problem
solving
in
dynamic
multi-institutional
virtual
organizations
[7.
An
important
issue
that
should
be
mentioned
is
that:
"the
sharing
that
we
are
concerned
with
is
not
primarily
file
exchange
but
rather
direct
access
to
computers,
software
data,
and
other
resources"
[4].
This
sharing
is
necessarily
highly
controlled
and
under
some
sharing
rules.
A
set
of
individuals
and/or
institutions
defined
by
such
sharing
rules
form
Virtual
Organizations
(VOs).
An
actual
organization
can
participate
in
one
or
more
VOs
by
sharing
some
or
all
of
its
resources.
This
resource
sharing
is
conditional:
each
resource
owner
makes
resources
available,
subject
to
constraints
on
when,
where
and
what
can
be
done
[4].
The
background
concept
in
grid
is
not
new.
As
a
real
of
fact,
the
collaboration
and
sharing
of
resources
in
a
geographically
distributed
environment
is
an
idea
existed
since
the
computer
domain
originated.
In
grid,
people
will
be
able
to
easily
access
to
unlimited
resources
connected
through
the
Internet.
Mechanisms
for
creating,
managing,
and
exchanging
information
among
entities
called
grid
services.
The
next
generation
of
scientific
experiments
and
studies,
popularly
called
as
e-Science
[8],
will
be
carried
out
by
communities
of
researchers
from
different
organizations
that
span
national
and
international
boundaries.
Grid
computing
[7]
enables
aggregation
and
sharing
of
resources
through
by
bringing
together
communities
with
common
objectives
and
creating
virtual
organizations
[4].
Data
Grids
have
evolved
to
tackle
the
twin
challenges
of
large
datasets
and
multiple
data
repositories
at
distributed
locations
in
data-intensive
computing
environments
[9].
Current
e-learning
systems
are
very
limit;
for
example,
it
is
vastly
impossible
to
compute,
photo-
realistic
visualizations
in
real-time
and
display the
computation
result
on
a
remote
screen
[10]
with
the
advanced
functionality
of
an
e-learning
grid,
students
could
be
provided
with
the
possibility
to
search,
visualize
and
accomplish
other
high
computational
e-learning
services
in
an
effective
way.
3.Web
Services
Internet
is
now
almost
service
oriented
and
based
on
messaging
and
standards
for
XML
interfaces
to
enable
coordinate
use
of
distributed
resources.
This
leads
to
high
level
of
interoperability
in
such
heterogonous
distributed
environment.
As
a
result,
the
basic
concept
and
building
block
for
internet
computing
becomes
the
Web
service.
A
service
in
this
context
is
a
network-enabled
entity
that
provides
some
capabilities.[1
1]
Service-based
architectures
take
legacy
application
functionality
and
expose
it
to
the
internet
in
a
reliable,
highly
available,
scalable,
flexible,
manageable,
and
secure
manner,
easy
and
reliable
internet-based
method
to
create
and
access
learning.
Web
Service
technology
has
emerged
as
a
new
paradigm
of
distributed
computing.
They
are
layered
on
the
top
of
standard
transfer
protocols
for
transmitting
messages
that
currently,
the
most
common
ones
are
the
XML-based
specification
SOAP
(Simple
Object
Access
Protocol),
UDDI
(Universal
Description,
Discovery
and
Integration),
and
WSDL
(Web
Service
Description
Language)
[12].
This
concept
is
illustrated
in
figure-1.
A
web
service
is
a
stand
alone
software
component
that
has
a
unique
URI
(Uniform
Resource
Identifier).
Web
services
present
another
alternative
distributed
computing
infrastructure
which
is
strongly
promoted
as
a
preferable
one
in
contrast
with
the
use
of
distributed
object
middlewares
such
as
Java
RMI
or
CORBA
[12].
3.1.Grid
services
A
Grid
can
be
defined
as
a
layer
of
networked
services
that
allow
users
single
sign-on
access
to
a
distributed
collection
of
computing,
data
and
application
resources.
Grid
services
allow
the
entire
collection
to
be
seen
as
a
seamless
information
processing
system
that
the
user
can
access
from
any
location
[13].
A
Grid
Service
is
a
Web
Service
which
conforms
to
a
set
of
conventions
(interfaces
and
behaviors)
that
define
how
a
client
interacts
with
a
Grid
Service.
Therefore,
Grid
Services
are
standard
Web
Services
with
improved
characteristics.
Two
advantages
of
web
services
framework
that
are
mentioned
in
[7]
as
important
reasons
for
using
web
services
in
Grid
are:
First,
the
need
to
support
the
dynamic
discovery
and
composition
of
services
in
heterogeneous
environments.
Second,
the
widespread
adoption
of
web
services
mechanisms
means
that
a
framework
based
on
web
services
can
exploit
numerous
tools
and
extant
services.
0-7803-9521-2/06/$20.00
§2006
IEEE.
632

Figurel.
Web
Se
heterogeneous
applications,
publicity
of
available
*'
j'...
....
..'
'..
'j'j
'services,
etc.
As
the
adoption
of
this
new
(Universal
Description,
Discovery
archnology
increases,
it
will
become
necessary
to
Integration)
offer
intermediary
platforms
that
make
it
easier
to
...
.....
.......
............j
....find
and
locate
services
and
composing
new
(Web
Services
Description
Languag§4rvices
from
the
existing
ones
[17].
.....The
success
of
e-learning
has
promoted
the
(Simple
Object
Basic
Protocol)
proliferation
of
different
kinds
of
e-learning-related
,..
software
applications
[17].
Next
generation
e-
learning
systems
will
use
Web
services
that
can
(over
TCP/IP)
match
learning
content
to
user
context
in
a
way
that
provides
a
customized,
personalized
experience.
Information
retrieval
(IR)
functions
that
serve a
critical
role
in
many
e-leaning
systems
can
be
4.Next
Generation
Digital
library
and
E-
Learning
Systems
As
it
has
mentioned
before,
according
to
the
huge
amount
of
data
being
stored
and
communicated,
and
also
increasing
number
of
users
interested
in
DL
and
EL
systems,
new
architectures
of
these
systems
should
be
able
to
address
issues
such
as
scalability,
flexibility,
interoperability,
availability
and
heterogeneity.
Next
generation
DLs
should
enable
transparent
access
to
distributed
data
sources,
ensure
communication
and
possible
collaborations
with
scientists
in
other
disciplines
facing
similar
problems,
define
an
open
scalable
middleware
architecture
to
build
on
top
of
existing
and
future
archives
to
facilitate
interoperability,
and
finally
provide
an
environment
as
flexible
as
possible
and
self-extensible[14].
In
the
area
of
digital
library,
few
efforts
have
been
done
to
use
novel
technologies
in
these
architectures.
One
progressive
effort
in
this
area
is
arco
project[14].
Arco
is
a
digital
library
storage
project
faced
several
challenges,
such
as
the
availability
of
peta-scale
storage,
seamless
spanning
of
storage
cluster,
administration
and
utilization
of
distributed
storage
and
computing
resources,
safety
and
stability
of
data
transfer,
scalability
of
the
whole
system,
automatic
discovery
and
monitoring
of
metadata,
etc.
It
can
be
inferred
that
the
efforts
in
Arco
project
just
cover
the
storage
aspect
of
DL;
however
by
using
novel
technologies
like
web
services
we
would
be
able
to
reach
more
flexible
and
scalable
architecture
for
these
kinds
of
systems
by
dividing
large
systems
to
interconnected
and
interactive
services.
On
the
other
hand,
in
e-learning
systems
[15],
recent
efforts
concentrate
on
the
reuse
of
application
functionalities.
However
most
of
these
efforts
in
e-learning
such
as
[16]
have
been
focused
on
the
reuse
of
learning
material,
a
few
of
these
researches
have
tried
to
introduce
web
service
as
a
preferable
technology
in
this
area
[10].
Some
E-
learning
systems
use
advantages
of
new
features
offered
by
Web
services
such
as
integration
of
distributed
or
their
functions
be
made
available
through
the
web
services
framework
[18].
Also,
by
using
web
services,
developers
can
provide
the
flexibility
a
learner
needs
in
tertiary
education
in
which
many
institutions
offer
courses
for
education
[15].
5.Grid,
Digital
library
and
e-learning
convergence
In
contrast
with
current
applications
which
may
use
high
performance
computing
as
a
secondary
task,
modern
systems
can
use
novel
technologies
such
as
grid
and
parallel
computing
as
well
as
web
services
to
reach
interactive,
collaborative
and
reality
based
learning
environments
[28].
By
proposing
the
use
of
grid
technology,
many
service
providers
and
content
providers
can
participate
in
various
VOs.
Using
the
concept
of
virtual
organization
in
Grid,
we
can
effectively
group
users
and
organizations
especially
for
cooperative
learning
and
participating
in
digital
library
instruction.
Organizations
and
institutes
that
contribute
in
developing
such
a
system
can
share
their
resources
and
services
forming
different
VOs.
These
organizations
can
cooperate
under
some
policies
to
reach
their
common
objectives.
Here,
we
need
a
middleware
for
uniform
access
to
all
theses
resources
that
belong
to
different
administrative
areas.
Additionally,
an
infrastructure
is
needed
that
insure
availability,
scalability,
security,
extensibility
and
interoperability
for
implementing
such
distributed
systems.
Each
organization
should
be
able
to
reuse
functionalities
and
services
as
well
other
resources
that
are
provided
by
other
organizations.
6.DLEL
Standards
and
specifications
Everyone
knows
the
role
of
standards
in
transmitting
and
receiving
data.
Just
like
other
areas,
standards
have
changed
Digital
library
and
e-
learning
systems
to
reach
more
stable
status.
0-7803-9521-2/06/$20.00
§2006
IEEE.
633

Interoperability
among
digital
library,
and
also
e-
learning,
content
and
system
components
is
a
key
factor
in
successful
implementation
of
these
environments.
Recently,
there
have
been
several
interoperability
specifications
and
standards
of
development
and
adoption
that
are
being
launched
by
a
number
of
organizations
and
consortiums[19].
Now
a
day,
there
are
many
organizations
join
together
to
promote
globally
scalable
solutions
for
digital
library
and
e-learning
environments.
Such
solutions
cannot
exist
without
standards
anymore
than
the
Internet
can
exist
without
standards
such
as
TCP,
IP,
HTTP,
and
HTML.By
means
of
well
defined
and
widely
adopted
standards,
some
goals
of
digital
library
and
e-learning
environments
can
be
reached
in
a
more
convenient
way;
for
instance,
we
are
prevented
from
lock-in
to
particular
vendors
and
products;
costs
are
lowered
;
standardized
methods
of
interoperability
eliminate
the
need
to
write
proprietary
interfaces
to
many
different
products;
standards
allow
content
to
be
produced
in
a
single
format
to
be
used
by
any
delivery
system;
standards
can
lead
to
more
choice
of
products
and
also
make
the
results
more
portable;
large
storehouses
of
reusable
content
are
accessible,
by
reducing
the
need
to
develop
to
multiple
systems,
and
by
allowing
to
create
modular
content
that
can
be
more
easily
updated
and
maintained.
In
general,
the
purpose
of
all
these
interoperability
standards
is
to
provide
standardized
data
structures
and
communications
protocols
for
digital
and
e-learning
objects
and
cross-system
workflows.
users
of
theses
systems
can
purchase
content
and
system
components
from
multiple
vendors,
based
on
their
quality
and
appropriateness,
with
confidence
that
they
will
work
together
effectively
[19].
Standards
are
being
specified
and
implemented
in
several
ways:
Data
models
with
XML
and
other
bindings,
Web-service
architectures
that
rely
on
W3C
protocols
such
as
SOAP,
WebDAV,
and
XQuery,
and
APIs
with
JavaScript
and
JavaTM
implementations.
7.DLEL
Middleware
Our
middleware
has
built
on
the
assumption
that
typical
digital
library
and
e-learning
systems
are
collections
of
activities
or
processes
that
interact
with
users
and
suitably
chosen
content.
This
enables
us
to
subdivide
the
main
functionality
of
these
systems
into
a
number
of
stand-alone
applications,
which
can
then
be
realized
individually
or
in
groups
as
Web
services.
Web
services,
on
the
other
hand,
are
offered
by
a
number
of
providers.
These
providers
can
cooperate
under
some
policies
in
the
form
of
some
grid
VOs
to
reach
their
common
objectives.
We
proposed
a
middleware
for
uniform
access
to
all
theses
resources
that
belong
to
different
administration
areas.
Many
service
providers
and
content
providers
can
contribute
in
developing
a
very
large
scale
integrated
digital
library
and
e-learning
system.
The
content
provider
in
the
simplest
case
would
be
a
user
that
shares
her
information
with
other
users.
I
On
the
other
hand,
since
digital
library
and
e-
learning
systems
have
many
common
objectives,
requirements
and
specifications;
we
developed
a
middleware
that
can
support
services
for
both
of
these
two
systems
at
the
same
time.
In
both
of
these
two
systems,
agents
play
a
great
role
in
implementing
services
such
that
they
can
response
to
users
in
an
effective
manner.
So
we
have
implemented
our
middleware
using
agent
technology,
while
we
tried
to
represent
each
agent
as
a
web
service
in
our
architecture.
Our
middleware
is
a
multi
agent
system
which
represents
grid
core
services
for
resource
sharing
and
other
basic
services
for
digital
library
and
e-
learning,
all
at
the
same
time.
Each
agent
in
this
middleware
is
created,
deployed
and
published
as
a
web
service.
DL
and
EL
basic
services
layers
are
the
heart
of
this
DLEL
grid
middleware.
In
these
layers,
agents
represent
basic
services
for
digital
library
and
e-
learning
systems
using
other
agents
that
exist
in
grid
core
services
layer.
Using
these
agents
users
are
able
to
access
and
share
all
types
of
information
including
papers,
magazines,
e-books,
etc.
with
other
users.
As
a
real
of
fact
except
sharing
other
resources(hardware
resources
such
as
CPU
Power
and
storage
media),
any
user
can
contribute
in
publishing
digital
content
in
this
system.
On
the
other
hand
any
organization
can
publish
its
digital
content
for
its
members
as
well
as
other
organizations.
In
these
two
layers,
basic
functionalities
of
digital
library
and
e-learning
system
are
provided.
There
are
multiple
agents
that
cooperate
with
each
other
to
perform
desired
I
0-7803-9521-2/06/$20.00
§2006
IEEE.
634

services.
In
figure.2
some
details
of
this
architecture
and
its
agents
has
been
shown.
By
using
our
middleware,
different
organization
and
institutes
will
be
able
to
cooperate
with
each
other
to
create
a
large scale
distributed
digital
library
and
learning
environment.
Using
core
services
that
are
provided
in
this
middleware,
any
type
of
users
can
join
to
the
grid,
and
use
its
services.
But
it
is
important
to
notice
that
this
middleware
just
provide
basic
service
for
users.
Organizations
that
aim
to
create
a
complete
library
and
educational
environment
can
use
this
middleware
to
structure
their
resources
and
to
cooperate
with
other
organizations
that
exist
in
the
Grid.
Then
they
are
able
to
create
their
own
additional
services
and
publish
them
to
others
as
web
services.
8.
Conclusion
Our
middleware
builds
on
the
assumption
that
typical
digital
library
and
e-learning
systems
are
collections
of
activities
or
processes
that
interact
with
users
and
suitably
chosen
content.
This
enables
us
to
subdivide
the
main
functionality
of
these
systems
into
a
number
of
stand-alone
applications,
which
can
then
be
realized
individually
or
in
groups
as
Web
services.
Web
services,
on
the
other
hand,
are
offered
by
a
number
of
providers.
These
providers
can
cooperate
under
some
policies
in
the
form
of
some
VOs
to
reach
their
common
objectives.
We
proposed
a
middleware
for
uniform
access
to
all
theses
resources
that
belong
to
different
administration
areas.
We
described
how
new
technologies
including
agent,
web
service
and
Grid
and
emerging
standards
can
be
applied
to
Digital
library
and
E-learning.
Leveraging
these
technologies
structure
digital
library
and
e-learning
environment
can
yield
significant
benefits.
In
this
paper
we
proposed
an
integrated
agent
based
middleware
architecture
for
digital
library
and
e-learning
on
the
Grid.
Convergence
of
three
major
technologies
to
proposing
a
middleware
for
creating
large
scale
Digital
library
and
e-learning
systems
including
agent,
web
services
and
the
grid
help
us
to
address
all
issues
that
have
not
been
addressed
by
current
architectures
yet.
Using
a
multi
agent
system
in
which
all
agents
have
a
high
degree
of
autonomy
different
grid
and
DLEL
services
have
been
effectively
deployed
in
our
middleware
architecture.
9.
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