Providing Web Services over DVB-H Mobile Virtual Web Services

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Providing Web Services over

DVB
-
H Mobile Virtual Web Services

Reporter:
藍元宏

Date: 2009/05/11

Vilas, A.F.; Redondo, R.P.D.; Arias, J.J.P.; Solla, A.G.; Duque, J.G.

Consumer Electronics, IEEE Transactions on

Volume 53, Issue 2, May 2007 Page(s):644
-

652

2

Outline


Abstract


Introduction


Scenario


Virtual Web Services


Virtual Web Services Over DVB
-
H


Conclusion

3

Abstract


This paper introduces the experiences in accessing
Web
Services (WSs)

from
DVB
-
H terminals.



This propose to
move the complexity

from client to the service
provider
by defining Virtual WSs (VWSs).



Virtualization
also gives the possibility of defining
QoS
-
aware
services

as well as
caching
-
based systems

to process the responses of
clients more efficiently.

4

Introduction


Web Services


Web Services (WSs) combine the best aspects of
component
-
based development

and
the Internet.



Web Services are accessed via
ubiquitous Web protocols

(ex: HTTP) and
data formats

(ex: XML).



WSDL
,
UDDI

and
SOAP

are considered the core of this
Web Service standards set
.


5

Introduction


Web Services Limitation


There are
two relevant problems

make it difficult to
achieve this desirable open framework where flexibility is
the key factor to
communicate WSs and mobile clients
.



On the one hand, and
inherently

to the WS technology, clients
are
bound to

a concrete service provider
at design time
.



On the other hand, today’s mobile devices
do not support the
excessive complexity

Mobile Web Services would need to allow
changing the provider

at run
-
time.

6

Introduction


Solution


This paper propose to introduce
an intermediate
virtualization layer

between mobile clients and WS
providers by using

WS virtualization
.



A

Virtual WS (VWS) is
defined within this intermediate layer

as a
conceptual service
grouping one or more WSs
.



A

light client for this heavy virtual WS is delivered to the mobile
receivers
while the VWS is

published as a standard WS
.



Client solves the
complexity problems
.

7

Introduction


DVB
-
H Overview


Regarding to delivering aspects,
broadcasting

is a
highly
cost
-
effective

way to reach large audiences.



DVB
-
H

(Digital Video Broadcasting
-
Handheld) is
considered a good candidate for being widely adopted,
especially in Europe.



DVB
-
H is forecast to be accessible by approximately 350
million mobile users by 2008.

8

Introduction


The Advantages of DVB
-
H


DVB
-
H is an
approved standard by ETSI

(European
Telecommunications Institute).



DVB
-
H benefits from existing DVB
-
T (DVB Terrestrial)
infrastructure components,
reducing initial investments
.



DVB
-
H
is clearly supported by the majority of mobile
device manufacturers

like Motorola, Nokia, Samsung, LG,
BenQ and Sagem


9

Introduction


DVB
-
H Technology


DVB
-
H has
improved the DVB
-
T standard

to
overcome
the communication problems

derived from the inherent
characteristics of
small and portable devices
.



Time
-
slicing
has been introduced to
reduce the average power
consumption

of the receiver and to enable
smooth

and
seamless
frequency handover
.



It is incorporated a module of
forward error correction for
multiprotocol encapsulated data

(MPE
-
FEC, Multiprotocol
Encapsulation Forward Error Correction), which
enhances the
reception

in the special conditions of handheld terminals.

10

Introduction


DVB
-
H and IP Protocol


IPDC (Internet Protocol Datacasting) is what
converts
DVB
-
H in an end
-
to
-
end broadcast system

for delivering
any type of digital content and services
using IP
-
based
mechanisms.



Download

by
FLUTE

(File deLivery over Unidirectional Transport)
and
streaming

by
RTP

(Real Time Protocol) respectively.



DVB
-
H ESG

(DVB
-
H Electronic Service Guide)
describes

the
available

IP Datacast
services
.

11

Introduction
-

Purpose


12

Scenario

13

Virtual Web Services


Overview


Virtualization is an
elegant solution

to
solve several open
problems in WS technologies
, like asynchronous
invocation, error control, high availability, quality of
service, etc.



The
binding process

in WS technologies, binding
at
design
-
time
, is an
important limitation
.



WS virtualization is based on
grouping one or more web
services

inside a unique wrapper, which is then
published
as a standard web service
which

called VWS
.

14

Virtual Web Services


Architecture


Who need
Services

Client software

Web Services

Service Provider

Virtual Web
Services

15

Virtual Web Services


Implementation


The

implementation of this VWS is virtually defined by
the
VWSDL document

(VWS Definition Language).



VWSDL is an
XML
-
based language

which has been defined as a
stand
-
alone language, i.e.
not as a WSDL extension.



VWSDL definition is
only useful to a VWS engine
.



On top of VWSDL, this paper
have defined VWSEL

(Virtual Web Services Extension Language), which
allows
the clients to use SOAP
-
Header elements to
add control
information

which
modifies the behavior of the engine.

16

Virtual Web Services




VWSDL & VWSEL Documents


VWSEL

}QOS

}caching

17

Virtual Web Services


Development Cycle


18

Virtual Web Services


Production Cycle


19

Virtual Web Services Over DVB
-
H


DVB
-
H standard specifies two ways
for broadcasting
content

by using, respectively, the
RTP

and
FLUTE

protocols.



RTP contents

are mainly devoted to
TV
-
like broadcasting
.



Other binary objects

(textual, applications, multimedia, etc.) can be
delivered in a
data carousel

over FLUTE
.



Both kinds of contents
can be locally accessed by

using
the information in the
ESG
.

20

Virtual Web Services Over DVB
-
H




ESG Generation


←Broadcast time

←Accessing


Information

←such as a WSDL

21

Virtual Web Services Over DVB
-
H


22

Conclusion


This
define an intermediate layer

between the WS
provider and the WS mobile client where virtualization is
encapsulated,
hiding complexity
,
availability

and
location
problems

to mobile clients.



As
complexity resides

in the
virtual Web Services
, we
have light clients,
more adequate for mobile devices
.



By combining
virtualization of services

(through VWS)
and
broadcast infrastructures

(FLUTE carousel over DVB
-
H); This paper enable
mobile devices to access Web
Services through the new open Web
.

Thanks for your attention!!