=Paper=
{{Paper
|id=Vol-61/paper-5
|storemode=property
|title=M-Services Meet Web Services: Architectural Opportunities for M-Commerce
|pdfUrl=https://ceur-ws.org/Vol-61/paper5.pdf
|volume=Vol-61
|dblpUrl=https://dblp.org/rec/conf/mservices/Coyle02
}}
==M-Services Meet Web Services: Architectural Opportunities for M-Commerce==
https://ceur-ws.org/Vol-61/paper5.pdf
Mobile Computing, Web Services and the Semantic
Web: Opportunities for M-Commerce
Frank P. Coyle
Computer Science Department, School of Engineering,
Southern Methodist University, Dallas, Texas 75275 USA
coyle@engr.smu.edu
Abstract. This paper focuses on the intersection of mobile computing, the
Semantic Web and Web services, and examines how these technologies serve
as a foundation for an architectural framework that provides new opportunities
for mobile commerce and services within organizations. Mobile technologies
introduce several advantages that cannot be attained through conventional
wired connectivity. These include localization and personalization, which
allows the delivery of customized information to users based on locale, identity
or a user role. Two technology initiatives that hold promise in helping realize
the potential of mobile computing are the Semantic Web and Web services. The
Semantic Web is an initiative supported by the W3C intended to support
semantic meaning and context for Web resources. Key technologies include
RDF and DAML for data categorization and inference. Web services represents
an approach for applications to communicate with each other automatically
over the Web using standard Internet protocols. Collectively, these technologies
open up new possibilities for leveraging the capabilities of mobile computing
where the Semantic Web supports contextual meaning and Web services
technologies allow registration and discovery of services based on mobile
context.
1. The Web and Mobility
Mobile computing is moving into a phase driven by high-speed bandwidth and
increasingly powerful device technologies. The auctioning of global spectrum to
support new, high speed third generation (3G) wireless networks is now giving rise to
high speed, multi-media Internet access to cell phones and wirelessly-enabled PDAs.
The rollout of 3G technologies and the emergence of wireless LAN technologies are
now important drivers for mobile commerce.
At the same time, device capability is increasing. Devices capable of increased
processing power are coming to market and the availability of Java on wireless
devices is opening new possibilities, not only for delivering data to mobile devices
but for using those devices to deliver information to the enterprise in new ways. The
Java 2 Micro Edition (J2ME) [1] allows developers to use Java to develop
applications for mobile devices including cell phones and PDAs. Companies making
use of J2ME include Research In Motion (RIM), with its Blackberry two-way
handheld devices; Korea’s Lucky Goldstar, with its J2ME-based CDMA mobile
phones; Sega with Personal Java for its Dreamcast consoles; Nokia with its EPOC-
based mobile phones; and Sony with its mobile phones.
1.1 Localization and Personalization
Among the unique features of mobile computing are localization and personalization.
Localization is the ability to locate wireless devices using either global positioning
(GPS) or through cellular technologies that pinpoint location to within several feet.
The ability to locate subscribers, coupled with the delivery of personalized
information, is viewed as an important aspect of wireless service for both consumers
and employees.
From a consumer perspective, localization provides opportunities to deliver
information to travelers about nearby restaurants and hotels. For businesses,
localization allows companies to track workers across a wide region and improve
company efficiencies. But the real impact is expected when mobile data sources serve
as data providers to organizations.
The other unique aspect of wireless is personalization. Because wireless network
providers already track user identity for billing purposes, applications can leverage
this information to personalize content based on user preferences and/or patterns of
usage. While technology forecasts predict significant revenues from wireless
technologies, the caveat is that the mobile Internet will succeed only if applications
are developed that can take advantage of the unique characteristics of wireless.
Work by Hjelm [2] has focused on the importance of context in accessing data
from wireless devices. In a mobile environment, users do not have the time to conduct
extensive searches while on the move. Mobile users require that supporting systems
understand who they are, where they are located and to deliver appropriate
information on demand. Solutions centered around Composite Capability/Preference
Profiles (CC/PP) [3] allow parameterized requests to be sent to servers that contain
both documents and user profiles that can help systems transform data for relevant
and efficient delivery over wireless networks.
2. XML and Mobile Commerce
One of the foundational building blocks of the Web is XML [4]. Most IT departments
have at least been tracking the Extensible Markup Language (XML) over the past
several years. During that time XML has emerged as the primary technology for
building bridges between different systems. XML’s successes include its use as data
exchange language between brokerage firms’ account systems and various stock
exchange order systems.
XML is finding increased utility in the wireless world. It is the basis for WAP, the
Wireless Markup Language and is also used as the basis for XHTML, the next
generation XML-compliant HTML that both WAP and i-Mode will be transitioning to
in the near future, thus strengthening the connection between wireless and XML. In
addition XML also is playing a major role in the middle tier through XML data
storage that is used as the source for a wide variety of clients and display types. It’s
common to expect a wireless strategy to support many different types of clients that
expect HTML, WAP, i-Mode, Palm Query Applications, AvantGo, Text, SMS,
Paging, or even XML content.
One key technology supporting XML for wireless devices is XSLT, the Extensible
Stylesheet Language Transform [5]. XSLT supports the Model-View-Controller
architectural style [6] where application data may be separated from specific display
requirements. As illustrated in Figure 1, XSLT templates can be used to store the
markup language-specific content (i.e. HTML, WML, etc.) and are 'applied' to the
XML using an XSLT processor.
Fig 1. XML maybe used to generate output for a variety of different wireless platform
through the use of XSLT
However, XML alone has limited capability to describe the relationships (schemas or
ontologies) with respect to objects. This is where the use of ontologies provides a
powerful way to describe objects and their relationships to other objects and has
opened up new ways of thinking about ways to integrate mobile computing with
conventional web access. One such initiative is the Semantic Web.
3. The Semantic Web
As wireless networks extend the reach of the Web, there is increasing need to add
meaning to the data that is both delivered and generated. This fact has not been lost on
the W3C which has been pursuing the concept of a Semantic Web - an extension of
the current web in which information is given well-defined meaning, better enabling
computers and people to work in cooperation. [7]
The goal of the Semantic Web is to support the mapping of existing and future
systems onto the Web, preserving the universality of the Web while supporting
localized domains. Organizations, for example, should be able not only to search the
vast wealth of resources available across the Web but also to restrict search among
partners and suppliers. To accomplish this requires an understanding of context. One
of the important technologies for providing flexible, context-sensitive data
descriptions on the web is RDF, the Resource Description Framework [8].
3. 1 RDF
RDF is an XML-based technology for managing context on the Web. It accomplishes
this through the expression of constraints whereby all objects, relationships, types,
and assertions are treated as first class objects. First class objects means that both
objects and relationships have their own URIs and are thus not constrained in how
they may be combined with each other. By giving first class identifiers to types,
relationships, and assertions, it is then possible for a Semantic Web to permit context
to determine the trustworthiness of the statements. Thus, it is not the intent of the
Semantic Web to codify truth but rather to provide structures that allow truth to be
evaluated in the context of each application. These are not new issues. The commerce
and financial communities have evolved techniques to manage exchange of
information without requiring perfect trust [9] with the same issues reappearing on the
Web.
However, RDF is only a starting point for representing semantic information that
can be used to support the exchange of knowledge on the Web. Key research
questions include how to generate semantic descriptions, how software agents can
discover these descriptions, and how agents integrate information from different sites.
Efforts to address these issues may be found in the work of Heflin and Hendler [10]
and Frankhauser [11] who have developed tools for using RDF to describe computer
science knowledge and the role of semantic annotations for reusable fragments of
course material.
Recent work has used RDF as a base technology to extend RDF descriptions to
allow new inferences. DAML, the DARPA Agent Markup Language, [12] has been
developed as an extension to XML and the Resource Description Framework (RDF)
with the goal of enabling the generation of new information-based descriptions of
entities.
3.2 DAML
DAML opens up the possibility of making inferences over limited domains. For
example, using DAML descriptors, one can assert that "Parenthood is a more general
relationship than motherhood." and "Marge is the mother of Bart" which taken
together allow a DAML processor to conclude that "Marge is the parent of Bart" even
though the explicit fact is not declared anywhere in a database. The latest release of
the language, DAML+OIL, [12] provides a rich set of constructs with which to create
ontologies and to markup information so that it is machine readable and
understandable.
4. The Emergence of Web Services
While a Semantic Web offers the possibility of supplying context for mobile
computing, the unique character of mobile networks opens up new opportunities to
leverage the emerging Web services frameworks centered around asynchronous,
message-based middleware [13]. Web services represents a shift in distributed
computing from tightly-coupled networks to a more loosely-coupled architecture that
is well suited to the addition of mobile networks and devices.
There are three major aspects to Web Services:
• A service provider who provides an interface for software that can carry out
a specified set of tasks.
• A service requester who discovers and invokes a software service to provide
a business solution. The requestor will commonly invoke a remote procedure
call on the service provider, passing parameter data to the provider and
receiving a result in reply.
• A broker or repository that manages and publishes the service. Service
providers publish their services with the repository and request access to
those services by creating bindings to the service provider.
The Web services technical infrastructure ensures that services even from different
vendors will interoperate to create a complete business process. Web services
accomplishes this by defining new ways of interacting through the registration,
discovery, and connection of software packaged as Web services. While still in its
early stages, Web services holds the promise of extending the Web from an
infrastructure that provides services to humans to one that provides services to
software looking to connect with other software. For IT organizations and end users,
Web Services makes possible new ways of thinking about the enterprise, working
with partners and suppliers and doing business over the Web. For mobile users these
opportunities include the following.
Corporate Intranets. The Web Services model of discovery and connection makes it
possible to use standard web technologies to promote communication and information
distribution within the organization.
Partners and Suppliers. Web Services opens up similar opportunities for connecting
between partners and suppliers. For example, by defining an interface that describes
how to access inventory data and publishing that interface on a server available to
trusted partners, a company can make timely information available to other
companies without requiring that partners share a common network. All that is needed
is an Internet connection and an agreement to share data on controlled access servers.
Internet-based e-commerce. By publishing a Web service interface on publicly
available server repositories, companies can tap into a global base of Web services-
aware clients who will be scouting repositories for matches to their needs. This ability
to describe functionality as a service interface also opens the door to new uses for
legacy systems.
4.1 Web Services and Mobile Commerce
Understanding the implications of Web Services for companies looking to leverage
mobile computing technologies, means realizing that Web services is at once an
architecture-driven technology and a process. As a technology it represents a set of
protocols that builds on the global connectivity made possible by the Internet and
open Web standards such as XML. As a process, it’s an infrastructure that supports
software discovery and connection over the Web and that is part of a growing
realization that the decentralized, loosely coupled, synergistic nature of the Web can’t
be ignored.
4.2 Technology and Architecture
The technology driving the Web Services revolution is the web itself. Until now the
web has acted primarily as an information resource for human users connecting to
servers around the world and following links to resources and information. Web
Services means taking this capability to the next level so that software can search for
services and obtain desired service functionality just as simply as users click on web
links. The potential of such connectivity is enormous since it means a move away
from reliance on network-limited systems and makes it possible to build systems
more reliably so that requirements such as robustness and maintainability may be
addressed [14].
Behind the move to Web Services are three main technical drivers:
1) XML - the tag-based language for supports the creation of industry-specific
data vocabularies and that is itself supported by numerous auxiliary
technologies for display, data typing and transformation.
2) HTTP - the web protocol used to deliver documents, pictures and all forms
of media across the web. HTTP’s role in Web Services is that it can be used
to pass XML data while ignoring details of programming language, platform
or operating system.
3) SOAP – the XML-based protocol that can be carried by HTTP to any web
server. SOAP is the XML glue that lets clients and providers talk to each
other and exchange XML data using HTTP, or even file transfer (FTP) or
mail (SMTP) protocols. SOAP also brings to the table a set of rules for
moving data through a network so that multiple recipients can contribute to
the data flow.
The cumulative effect of these technologies is a fundamental change in how we
now think about distributed computing. Prior to SOAP, doing distributed computing
interaction options meant choosing from a palette that consisted of either Microsoft’s
Distributed Component Object Model (DCOM), Java’s Remote Method Invocation
(RMI), or the Object Management Group’s Common Object Request Broker
Architecture (CORBA). While these technologies are still in widespread use today,
their primary drawback is that they limit the potential reach of the enterprise to
network nodes that share the same infrastructure. With SOAP, however, the potential
space of interconnection is the entire Web itself. This is why there is such intense
interest in XML and SOAP. It is out of this new capacity for interaction that Web
services emerges and opportunities for M-services arise.
4. 3 The Process
While the various technical forces (XML, HTTP, SOAP) lay the groundwork for
platform independent software interconnection, there still remains the problem of how
software systems can actually begin to communicate with other software systems
written in different languages and running on the different platforms.
Fig 2. The Semantic Web and the Web Services’ XML-based protocols opens up new
opportunities for mobile commerce.
To make the possibility of interconnection a reality requires an agreed upon process
for one system to find another and begin communicating. The Web Services vision is
that systems with no prior knowledge of each other can begin to communicate despite
internal differences. Web Services addresses this problem by defining rules of
engagement that build on HTTP, SOAP and XML. These new rules of engagement
provide:
•Description: The Web services model specifies white pages that list the
identity of a service provider, yellow pages that categorize services and green
pages that describe how to connect and use a service. Providers are responsible
for defining this information.
•Exposure: Web services repositories host the white, yellow and green pages.
Potential clients query repositories and to download descriptors that tell a client
how to connect and use the services.
•Invoking: Downloaded descriptors tell clients how to invoke a service. The
common method of communication is SOAP over HTTP. XML-RPC, a SOAP
capability, allows language independent remote procedure calls to be sent to a
Web services supplier.
•Delivering data/services: When the service has been invoked, XML-RPC
returns the any requested data back to the initiating application.
4.4 Protocols Support the Process
As illustrated in Figure 2, the process behind the Web Services model is supported by
XML and SOAP. Built on top of these two protocols are UDDI and WSDL. UDDI
provides a uniform way to describe and discover services and to obtain details of how
to connect and interact with Web services providers. UDDI stems from a cooperative
agreement among Microsoft, IBM, and Ariba on an XML-based specification for
establishing a registry of businesses and services on the Internet. Since the initiative
began in August 2000, the project has expanded to over 260 UDDI community
members and is one of the main drivers behind the acceptance of Web Services.
However, as UDDI is evolving, it is clear that many of the initial uses of the
repository idea will occur behind corporate firewalls where private registries will be
available internally or among a closely knit family of trusted partners and
collaborators to facilitate enterprise wide sharing and application integration. By
starting small on less critical projects, managers and developers can gain the
experience needed to migrate to more ambitious projects beyond their corporate
boundaries.
WSDL is an XML-based protocol used to describe the specifics of accessing a
Web service. Details include the type and number of parameters passed to a service
and the type and structure of the result returned. Once a Web service has been
discovered (via UDDI), WSDL provides the details of how to actually bind and
interact with that service. WSDL supports direct client interaction with a Web service
over standard Web protocols rather than requiring special networking software
installed on each machine.
5. The Semantic Web Meets Web Services
Mobile computing is undergoing the same growing pains experienced by other
emerging technologies. After an early period of inflated expectations fueled by over
active and aggressive marketing, mobile computing for the enterprise appears to be
moving to a more mature phase where we are beginning to understand how to deploy
wireless applications.
The big challenges facing IT managers is how to position, manage and leverage
wireless technology within the organization and to manage the data for delivery to
and receipt from mobile devices. To date, the focus has been on:
1) business-to-consumer (b2c) – using wireless technology to reach out directly
to consumers.
2) business-to-employee (b2e) – using wireless technology to make corporate
data available to mobile workers
3) business-to-business (b2b) – using wireless technology to create new
efficiencies in dealing with business partners and suppliers
For these approaches, the most important technology driving a wireless web has
been XML. Although not a wireless technology, XML is widely used to represent
data in a simple, standardized way and to deliver data for wireless networks. It is also
the basis for two important initiatives – Web services and the Semantic Web.
Both the Semantic Web and Web Services provide synergies that open up new
possibilities of software interconnection. Web services protocols such as UDDI and
WSDL allow software to interconnect without the burden of requiring a common
underlying proprietary network. Now add to this capability new dimensions of
context and ontology based on Semantic Web technologies such as RDF and DAML
and we may well be on the verge of new ways of thinking about mobile computing.
First, as a means to direct localized and personalized data to mobile devices, but
perhaps more importantly, to offer context and deduction to the new text, audio and
visual input collected from mobile devices. This combination of semantics and data
has the potential to revolutionize the web as we know it today.
6. Summary
The intersection of mobile computing, the Semantic Web and Web services
technologies provides a fertile ground for creating new opportunities for mobile
commerce and services within organizations. The Semantic Web initiative, supported
by the W3C, supports semantic meaning and context for resources on the Web. Two
of its key technologies, RDF and DAML, enable data categorization and inference.
For data delivery to and from mobile devices, requirements for semantics and context
are critical. Coinciding the increasing capabilities of mobile networks and devices,
Web services technologies are emerging to help automate communication between
software entities over the Web. At the center of both Web services and the Semantic
Web is XML and XML technologies.
Together, both the Semantic Web and Web Services open up new possibilities for
leveraging the capabilities of mobile computing with the Semantic Web supporting
contextual meaning and Web services technologies allowing registration and
discovery of services based on mobile context.
References
1. John W. Muchow, Core J2ME Technology. Sun Microsystems Press, 2001
2. Johan Hjelm, Semantics for the Wireless Web. Keynote presentation. IST Semantic
Web Technologies Workshop, Luxembourg, November, 2000
3. The World Wide Web Consortium, Composite Capability/Preference Profiles
(CC/PP): A user side framework for content negotiation. W3C Note 27 July 1999.
http://www.w3.org/TR/NOTE-CCPP/
4. The World Wide Web Consortium, Extensible Markup Language (XML) 1.0 (Second
Edition). http://www.w3.org/TR/2000/REC-xml-20001006
5. World Wide Web Consortium, XSL Transformations (XSLT) Version 1.0.
http://www.w3.org/TR/xslt
6. Mary Shaw and David Garlan, Software Architecture. Perspectives on an Emerging
Discipline. Prentice Hall, 1996
7. Tim Berners-Lee, James Hendler and Ora Lassila, The Semantic Web, Scientific
American, May 2001.
8. The World Wide Web Consortium, Resource Description Framework (RDF) Model
and Syntax Specification. W3C Recommendation 22 February 1999.
http://www.w3.org/TR/1999/REC-rdf-syntax-19990222
9. Joseph Reagle, Trust in Electronic Markets. First Monday. Vol 1, No. 2, August,
1996
10. J. Heflin and J. Hendler, A Portrait of the Semantic Web in Action. IEEE Intelligent
Systems, 16(2):54-59, 2001
11. Peter FrankHauser, Teachware on demand – the role of semantic annotations. IST
Semantic Web Technologies Workshop. Luxembourg, November, 2000.
12. The World Wide Web Consortium, DAML+OIL (March 2001) Reference
Description. W3C Note 18 December 2001
13. Frank Coyle, XML, Web Services and the Data Revolution. Addison Wesley, 2002.
14. Jan Bosch, Design and Use of Software Architectures. Addison Wesley, 2001