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 onVolume 53, Issue 2, May 2007 Page(s):644 - 652

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Outline

• Abstract• Introduction• Scenario• Virtual Web Services• Virtual Web Services Over DVB-H• Conclusion

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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.

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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.

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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.

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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.

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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.

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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

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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.

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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.

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Introduction - Purpose

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Scenario

砰!!!

Location: {GPS value}Services Provider: Virtual Traffic Web ServicesTraffic Flow: {Slow, Sluggish, Free Flow}Incident: {None, Minor, Moderate, Severe}

Private Traffic Center1Government Traffic Center

Virtual Traffic Web Services

Private Traffic Center2

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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.

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Virtual Web Services – Architecture

Who need Services

Client software

Web Services

Service Provider

Virtual Web Services

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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.

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Virtual Web Services – VWSDL & VWSEL Documents

VWSEL}QOS

}caching

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Virtual Web Services – Development Cycle

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Virtual Web Services – Production Cycle

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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.

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Virtual Web Services Over DVB-H – ESG Generation

←Broadcast time

←Accessing Information

←such as a WSDL

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Virtual Web Services Over DVB-H

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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!!