Jan Buck, Frederic Majer, Matthias Schmitt, Patrick Freudenstein and Martin Nussbaumer
Institute of Telematics, University of Karlsruhe (TH), Engesserstr. 4, 76128 Karlsruhe, Germany
Keywords: Mobile tagging, object hyperlinking, automatic identification and data capture.
Abstract: Within the last years camera phones have been established as an everyday appliance. Along with the advent
of these appliances so called “mobile tagging applications”, arose. Physical objects are tagged with a visual
code containing the URI of a resource. Camera phones are used to capture these visual codes and to access
content related to physical objects. In most current mobile tagging applications the evolution of content
associated with physical objects is not considered. Thus a later change and adding of resources is not
supported. Taking these problems into account we present a novel framework for the development and
evolution of advanced mobile tagging applications, called TagLink.
By the end of 2007 more than one billion camera
phones will be in use. While in 2006 40% of US
mobile phone users had a camera phone, in 2007
already 60% possessed a mobile phone with this
functionality (Meyers 2007). Along with the
establishment of camera phones as an everyday
appliance, a new trend, „mobile tagging“ arose. A
tag containing a barcode that encodes the URI of a
resource is put up at physical objects. Camera
phones are used to capture these barcodes and
subsequently software running on the phone decodes
them. Mobile web user agents can be used to display
content linked from barcodes.
Although endeavours to link real world objects
and the information space have already been made
before the current mobile tagging trend, all these
approaches couldn’t involve the public in a similar
way due to the limited distribution of appropriate
appliances. Nevertheless many of the developed
systems, known as Automatic Identification and
Data Capture (AIDC) systems (Smith 2002), realise
advanced functionalities not considered in current
mobile tagging solutions. An important drawback of
current applications is the linking from a physical
object to a resource by hard encoding the URI of the
resource in a tag. The change of a resource demands
republishing all tags linking to that resource. This is
even aggravating in 1-n or n-n relations between
resources and tags. Furthermore only the assignment
of a single resource per barcode is allowed.
Taking these problems into account, we
introduce a framework for the development and
evolution of advanced mobile tagging systems.
Section 2 outlines a scenario revealing the
unexploited opportunities of current approaches. In
section 3 the TagLink approach is presented. In
section 4, we give a brief overview of related
approaches and conclude with a summary and an
outline of planned future work in section 5.
In the following, a scenario for the employment of
mobile tagging systems is described and
requirements of a platform supporting this scenario
are derived.
In a generic scenario tools can be used to
produce tags that contain links to resources. These
tags are attached to physical objects. Individuals can
use camera phones to capture barcodes and navigate
to the resources encoded in them using a web
browser. This approach is appropriate in scenarios
where objects shall be tagged only short-term and
resources are not underlying change. In scenarios
where information associated with physical objects
evolves and users collaborate in the evolution of the
information space this approach falls short.
Buck J., Majer F., Schmitt M., Freudenstein P. and Nussbaumer M. (2008).
In Proceedings of the Fourth International Conference on Web Information Systems and Technologies, pages 321-324
DOI: 10.5220/0001528803210324
The problems revealed by this simple scenario
can be avoided by introducing a mediator that links
tags to resources. That way the assignment of
resources to barcodes can change and additional
resources can be assigned. Such additional
assignments comprise advanced interactions on
resources like adding reviews or comments by end-
users. Thus the quality of the provided information
can be enhanced. Given this architecture dedicated
scenarios become possible.
2.1 The Library Scenario
A library could offer a service that provides
additional information on books by acting as a
mediator between ISBN-13 (International ISBN
Agency. 2005) barcodes attached to book covers and
electronic resources. These barcodes encode the
International Standard Book Number (ISBN) of a
book. Client applications decode this information
and request additional resources on books from a so
called resolver service.
Figure 1: Library scenario.
In the following we will describe a possible
sequence. As depicted in Figure 1 a library visitor
uses his camera phone to capture a barcode attached
to a shelf in the library that contains the URI of the
library’s resolver service (1). The visitor uses a
mobile application to request the resolver service (2)
and retrieves information concerning the library.
Subsequently the visitor can capture ISBN-13
barcodes printed on book covers (3) and request the
library resolver service for resources associated with
the ISBN encoded in the barcode (4). Using web
browsers or special mobile applications these
resources can be accessed (5).
The types of resources provided by the library
can vary from information about the author, the
book, the availability of the book, other books of the
same author or related books and their location in
the library. Moreover users can enlarge the provided
information by providing additional resources. They
can write reviews for books or comment content and
thus enhances the quality of information.
Furthermore one could imagine that visitors are able
to perform “actions” on books (6). For example it
would be possible that a library visitor just walks
through the library and scans the barcodes of books
he wants to lend and at the end of his visit picks up
all selected books at the lending. Another
imaginable service provided by the library would be
the sale of books in cooperation with publishing
2.2 Requirements
In the following we will present basic requirements
of a framework supporting the development and
evolution of advanced mobile tagging applications.
Description: A central requirement is the ability to
describe real world objects in a simple and
extensible manner. Additionally bidirectional
relations between these objects and virtual resources
have to be allowed.
User Involvement: By involving users in the
creation of virtual counterparts to physical objects
and the distribution of barcodes linking to them, a
rapid growing of interconnections between the real
world and the information space can be achieved.
Moreover users can review and comment the
helpfulness and correctness of the provided data.
Mobility: Special conditions of mobile applications
have to be considered. If no connection to electronic
resources can be established or the mobile appliance
is unsuitable for the processing of a resource, the
system must support collecting and later processing
of resources.
Standard Orientation: Applications should base on
existing web standards. That way interoperability
with existing web applications is ensured and
isolation from technical trends is prevented.
In the following section we present the TagLink
framework, a framework supporting the
development and evolution of mobile tagging
3.1 Overview
In contrast to most current mobile tagging
approaches we propose an indirection between
physical barcodes and electronic resources. As
depicted in Figure 2 a barcode can be associated
with multiple topics, which can be considered as
WEBIST 2008 - International Conference on Web Information Systems and Technologies
containers for content. Likewise topics can be
associated with multiple barcodes.
Barcode Topic Content
Figure 2: Indirection between Barcode and Content.
By allowing multiple associations of topics to
barcodes, topics serve as items of reuse that can
evolve independently over time. To support this
approach the TagLink-framework provides a
resolver service that acts as a mediator between
barcodes and resources.
Figure 3: Overall architecture of an application developed
with the TagLink framework.
The overall architecture of an application build on
the TagLink-framework is depicted in Figure 3. The
identifier of a barcode combined with the URI of the
according resolver service is encoded in a barcode.
Users capture barcodes using camera phones.
Mobile applications decode the included
information, communicate with the resolver service
and retrieve resources related to barcodes. Common
resources are electronic documents and Web
Services. But resources especially tailored to the
needs of a dedicated application are possible also.
To achieve a maximum of flexibility and
extensibility concerning different types of resources
used in mobile applications, resources are defined in
RDF notation (Klyne G. and Carroll J. J. 2004) and
are managed in a triple store. Thereby multiple
applications can operate on a single triple store
whereby synergy effects concerning the tagging of
real world objects can be utilized. In Figure 4 an
exemplarily RDF graph for the library scenario is
lib :A Tag
lib :ADoc
tag :topic
Figure 4: Example of a RDF graph.
The semantic model of an application can be
accessed using mobile clients as well as an
Administration Web Application by communicating
with the resolver service. In the following the
technical framework will be presented in detail.
3.2 Resolver Service
The resolver service is the core component of the
TagLink architecture. It is a Web Service providing
access to resources associated with barcodes.
Existing triple stores can be used to store and
manage RDF resources. The built-in reasoning
support of triple stores can be applied to filter
relevant resources on the server-side and thus to
minimize client-side computation. Moreover the
resolver service offers interfaces for the
management of resources and provides functionality
to create barcodes that can be printed and attached to
physical objects.
3.3 SmartTag Mobile Application
On the client side the TagLink framework consists
of an extensible client application, called SmartTag
that allows users to perform operations on the
application model managed by the resolver service.
A plug-in mechanism allows the extension of the
SmartTag application with forms, tailored to special
resource. When starting the program all registered
plug-ins are loaded and the user is presented an
overview of all possible operations. To meet the
special conditions of mobile applications the
SmartTag application comprises a bookmark store.
Thus resources can be copied to the bookmark store
and processed later.
3.4 Administration Web Application
Beside the SmartTag mobile application the
TagLink framework comprises an Administration
Web Application that can be used by administrators
and content providers to manage resources.
Furthermore the Administration Web Application
can be used to process resources stored in the
bookmark store of the SmartTag application.
In the following existing approaches using AIDC
methods to connect physical objects with the
information space will be described briefly.
WebStickers is introduced in (Ljungstrand 2000)
and deals with the idea to use tagged physical
objects as bookmarks for websites. Thereby the
physical surrounding is regarded as an extended
workspace. Although many of the presented
requirements were met, the approach lacks regarding
extensibility as it focuses only bookmarks.
Furthermore expensive barcode scanners are
required, what increases the price of the system.
A very comprehensive approach is the
CoolTown (Kindberg 2000) project. Due to the age
of the project modern appliances like camera phones
have not been considered. The goal of the project
was to provide an infrastructure for nomadic
computing. The project builds on web technologies
and parts of the approach were considered in the
TagLink approach. However the evolution and reuse
of content is not considered.
Another examined approach is the ETHOC
(short for “EveryThing Has Online Content”)
project, described in (Rohs 2003; Rohs 2004). The
project covers the creation, administration and
mediation of virtual counterparts of real world
objects. Physical objects are tagged with barcodes
encoding an identifier. The creation and
modification of content is restricted to a web
interface only and allows no support by the client
application itself. Thus focussing stronger
involvement of end-users is hindered.
In this paper we presented a novel approach for the
development and evolution of advanced mobile
tagging applications. Derived from an exemplary
scenario, requirements of such a framework were
presented. Taking these requirements into account
the TagLink framework supporting the development
and evolution of mobile tagging applications was
introduced. In the future we will focus our research
on the development of an ontology for mobile
tagging applications. Moreover we will evaluate the
framework using alternative identification
technologies like Radio Frequency Identification
(RFID) (Molnar 2004).
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