2010 IEEE 24th International Conference on Advanced Information Networking and Applications Workshops
Towards a Platform for User-Generated Mobile Services Jürgen Tacken1, Stephan Flake1, Frank Golatowski2, Steffen Prüter2, Carsten Rust3, Alexandra Chapko4, Andreas Emrich4 1
Orga Systems GmbH, Am Hoppenhof 33, 33104 Paderborn, Germany University of Rostock, Richard-Wagner-Str. 31, 18119 Rostock-Warnemünde, Germany 3 Sagem Orga GmbH, Riemekestr. 160, 33106 Paderborn, Germany 4 German Research Center for Artificial Intelligence, Stuhlsatzenhausweg 3, 66123 Saarbrücken, Germany e-mail: {jtacken,sflake}@orga-systems.com, {frank.golatowski,steffen.prueter}@uni-rostock.de,
[email protected], {alexandra.chapko,andreas.emrich}@dfki.de 2
There are already many investigations on establishing communities via their members’ mobile devices, but the targeted application areas are mostly related to rather generic presence and chat services, and not really in building social communities. On the other hand, mobile devices nowadays allow users to generate digital content that can easily be uploaded to centrally-provided services. Soon, this will evolve further and the mobile world will provide not only contents but also ad-hoc user-created services from the “long tail”, i.e., a large number of unique services with a comparatively small number of users. The mobile terminal will evolve to become also a server. When put into exploitation directly by using the mobile device, a mobile user will provide constantly updated information, relevant to other users’ instantaneous interests. The authors assume that technologies enabling the creation, deployment, discovery and sharing of user-generated mobile content and services are key to the further evolution of the mobile world [1]. Individuals will become “super prosumers”, i.e., producers, providers, and consumers of mobile content and services. The super prosumer concept responds to the most relevant driver of mobile usage beyond anywhere and anytime communication: it is the instantaneous and personalized response to a need for communication, information, and entertainment using powerful ubiquitous user devices and mobile network infrastructures. This article aims at presenting the first results of investigating the state of the art and the requirements to let the vision of the super prosumer concept become true. Section II reviews the current technologies for easy creation and discovery of mobile services as well as their recommendation, security, and revenue sharing. Section III lists the identified requirements for user-generated mobile services, and Section IV presents our concept to fulfill these requirements. Section V contains a conclusion and outlook on future work.
Abstract—In the near future, the trend of user-generated content and services currently observable in the Internet domain will also affect the mobile environment: mobile users will become able to easily create content and small services while on the move and offer them to social communities. Mobile users will no longer be pure consumers, they will also become producers and providers of mobile content and services. However, to let this vision come true, a new mobile service platform has to be built and established. In this article we are surveying relevant aspects, like service technologies, semantic search and recommendation mechanisms, revenue sharing, and security technologies. Based on that survey, requirements and challenges are identified. By means of an application scenario from the health and fitness domain, we present a first concept for a platform that allows for building virtual communities with easy and inherent support for real physical meetings. Keywords-User-generated mobile services, micro services, super prosumer, context-based recommendation, security, revenue sharing
I.
INTRODUCTION
Facebook, YouTube, MySpace … The producer role of users is boosting the Web. With a growth rate of nearly 700%, user-generated content reached 12% of the total traffic of fixed-line Internet in April 2007, with approximately 60 million personal blogs and around 100 million videos. At the end of 2009, more than 80 million images are uploaded to Facebook each day, and this number is continuously rising1. The same growth can be noticed for videos on YouTube. Soon this trend will move to the mobile environment, which is much more suited to the way we carry out social interactions, i.e., anywhere, anytime. None of the existing platforms to build communities and community services really makes use of features especially enabled by mobile devices, like implicitly having information about the users’ context, such as the current location of the user. However, using such information allows to bring the community members not only virtually but also physically together. 1
II.
The creation of services for social communities that share related information among each other has already started. But these services mostly request or store information only on a centralized community server. Therefore, the spontaneous creation of new communities which require special infrastructures is not possible. Currently, a service provider
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978-0-7695-4019-1/10 $26.00 © 2010 IEEE DOI 10.1109/WAINA.2010.77
STATE OF THE ART FOR MOBILE SERVICES
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who creates a common platform for the community is necessary. One popular example is OpenStreetMap [2] which is a map created only by GPS information uploaded by the users of this service. Everyone with a GPS tracking device can already participate in this project and change his role to a mobile producer of content. Furthermore, any kind of information can be shared through popular websites like Facebook, YouTube, or MySpace. Communities with millions of participants can easily be created, but users have only very limited possibilities to publish their information. In general, no support for mobile devices or information generated by mobile devices is provided by these platforms. On the other hand, mobile devices – in particular mobile phones – have an ever increasing calculation power, connectivity, and different embedded sensors, while the average cost for such devices is nearly constant. The latest generation of mobile phones and communication solutions is already showing the potential of mobile phones as universal tools. In the near future, their functionality will reach the mainstream market. It is expected that new tools and application areas will emerge that employ mobile phones as universal embedded devices capable to communicate via a broad range of wireless technologies, e.g., IMS, WLAN, Bluetooth, or ZigBee. In the domain of fitness and health, manufacturers and service providers have already created some platforms [3] [4] [5]. These platforms allow the upload of information related to sports, like running, walking, etc. Users are recording sensor data with their mobile devices, like GPS sensors or heart rate sensors, and can then upload that data from their laptop or PC at home to the platform. Thus, recording and uploading is already possible, however, not yet seamlessly while on the move. A currently still missing functionality is the possibility for users to produce own spontaneous services and share them with other interested people. The communication infrastructure for these services is allocated by the service provider. The common method to achieve this is an Internet connection and Web pages that are accessed via HTTP. The meaning and how users have to interpret the information is also given by the service provider. For the super prosumer, these technologies cannot be applied, because the flow of information is different. However, for these aspects appropriate technologies are already available. They are discussed in the following sub-sections.
Service Description Language) and the communication is realized with SOAP (Simple Object Access Protocol). The OASIS WS-DD working group has published the DPWS (Device Profile for Web Services) standard [6]. DPWS allows a secure message exchange for resource-constraint devices. The main technologies used in DPWS are WS-Discovery, WS-SOAP over UDP, SOAP, WSDL, and XML Schema. This allows for a dynamic implementation of services also on mobile devices. Another technology is the Common Object Request Broker Architecture (CORBA), which is an advanced technology similar to Web Services. The major differences of CORBA are the need of an Object Request Broker (ORB) library and the communication with the General Inter-ORB Protocol (GIOP), which is blocked in most firewalls. Furthermore, this architecture is very complex and cannot fulfill the requirements of embedded devices. The Representational State Transfer (REST) architecture style has also several advantages. The REST architecture is similar to the World Wide Web (WWW). All data are handled as a resource and each resource is an atomic data unit. Only a strong limited number of methods for the manipulation of a resource is specified, and each method works with a fixed functionality. Therefore, the implementation of applications for devices is very easy compared to Service-oriented Architectures. However, although this technology allows the creation and usage of own services, it cannot be done without advanced knowledge about services creation. B. Semantic Search based on Annotations Mobile user-generated services – which can be very short-lived – demand for novel discovery approaches. Nowadays data can be enhanced with semantic meta information which result in semantic search engines. Semantic search engines utilize ontologies and semantic annotations to associated contents to the annotations and domain knowledge. Ontology defines vocabulary and logical relationships between concepts in a discourse domain which can be also used for reasoning purposes. It is independent of the actual data but provides a common understanding of the semantics of the given domain. It is used for the explication of implicit and hidden knowledge in order to overcome the problem of semantic heterogeneity [7]. Searching mechanisms for semantic annotations differ from the conventional keyword-based engines. Different preprocessing mechanisms are used, e.g. based on the ontology structure or linguistic methods, and different information discovery mechanisms such as discovering new ontologies and annotations for indexing by crawling. Typical examples of semantic search engines are Swoogle [8] and OntoSelect [9]. While Swoogle tries to become Google for the Semantic Web, OntoSelect also provides statistical analysis on the searched ontologies, e.g. analyses which labels or languages are most popular in the searched ontological dataset. A current challenge for semantic search engines is the problem of search over very large volumes of (semantic) data. Examples efforts in this research area are LarKC [10] and tools such as ORDI [11] and SWSE [12].
A. Service technologies The new super prosumer has special requirements for the engaged communication technologies. The main challenges here are the embedded devices with limited resources and the fact that mobile services have very dynamic characteristics: changing locations, available bandwidth and physical network, and seamless connectivity. The remainder of this section gives an overview about technologies that enable the communication between mobile devices. Web Services (WS) are an established Internet technology for a dynamic exchange of data. Typically, these services are described by means of the XML-based WSDL (Web
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ties” domain. Van Setten et al. [23] describe a context-aware recommendation engine for mobile tourist applications which uses ontologies. In their approach a hybrid system is constructed by combining a recommender system and a context-aware system. Here, recommendations are adapted automatically if the context of the user changes, i.e. if the sensors of the mobile device detects an increase of the user’s speed, the application assumes that the user is driving and increases the radius of the area for providing recommendations. Zhou et al. [24] developed a recommendation system which is based on user preference, situation context, and capability context for supporting context-aware media recommendation for smart phones. Context is represented via ontology-based context models which include the user’s media preferences.
C. Semantic Search Engines for Web Services Semantic search engines for Web Services are another direction for a semantic search apart from searching semantically annotated contents. Latest developments in service description languages such as SA-WSDL and OWL-S show the growing importance of semantically annotated services [13]. SA-WSDL is a W3C recommendation from 2007 enabling linkage of semantic annotations to a Web Service designed with typical, WSDL-based technologies. A semantic Web Service search engine using this technology is being produced by a start-up company named Seekda [14]. The underlying ontology is WSMO (Web Service Modelling Ontology) which is a meta model of WSML, a family of languages with the goal to provide ontology languages for the semantic Web [15]. An example of such is OWL-S which specifies how to annotate content on the Web [16].
F. Security, Privacy, Trust, and Identity Management Important issues in the context of mobile user-generated services are security, privacy, and trust as well as the closely related issue of identity management. For Web Services, WS-Security [25] is a standard for applying security mechanisms. It defines a set of SOAP extensions providing message authentication, message integrity, and message confidentiality. WS-Security supports for multiple security tokens, trust domains, signature formats, and encryption technologies. It is a message-level security and working in the application layer, no special transport layer technique is required. Concerning the management of identities, which is needed to perform secure authentication, user-centric identity management standards have to be considered. Well-known examples are OpenID [26], CardSpace and Information Cards [27], and Liberty Alliance. In addition, SIM (Subscriber Identity Module) cards are also providing security mechanisms. The SIM card is wellestablished as a tamper-proof security device in mobile telecommunication scenarios. Its primary purpose is to identify a mobile phone user to the operator's network in a secure and consistent way. The majority of today’s SIM cards is Java enabled and conforms to the Java Card 2.2 specification [28]. There are several additional standards for SIM cards that support value-added applications (e.g., Short Message Information Service) and executable applications. In general, SIM-based applications ensure authenticity, integrity, confidentiality, and privacy. For deploying these security enhancing applications within mobile services, concepts for communicating to the SIM on application level are needed. One frequently used ability is the SIM card Application Toolkit (ETSI TS 102 223). It defines a set of commands and procedures enabling the card to contain applications specific to the issuer (i.e., the network operator), allowing the operator to deploy services like, e.g., information and location based services, banking and Internet access. New approaches from bodies like Java Card Forum, ETSI or Open Mobile Alliance (OMA) aim at utilizing Web technologies in the smart card world. This could extend the mashup idea to the usage of SIM cards in mobile services. A Smart Card Web Server (SCWS) is an HTTP server that is implemented in a smart card, i.e., in the mobile con-
D. Traditional Recommendation Mechanisms Another type of information retrieval is recommendations. The recommendation problem is formulated as the problem of rating items that have not been seen by a user [17]. One approach is to compare new, unrated items with items that have already been judged and are similar to the new item also know as content-based recommendation [18]. Another approach known as collaborative filtering is to base recommendations on persons with similar preferences instead of similar objects. Hybrid recommendation systems combine both approaches to overcome the cold-start problem, i.e. the fact that a critical mass of ratings has to be available for providing good recommendations. In this context personalization of recommendation becomes a crucial issue in information search and retrieval processes. Personalization means the incorporation of additional user-specific information and can be achieved for instance via incorporating context data. Context is defined as any information that can be used to characterize the situation of entities (person, place or object) that are considered relevant for the interaction between a user and an application, including the user and the application themselves [19]. In recent attempts, context-aware recommender systems have been combined with ontologies to further improve the recommendation by adding semantics to the context. An overview of existing approaches regarding context-aware systems is given in [20]. E. Context-based Recommendation Implementation of a context-based recommendation system in a mobile environment is particularly difficult due to the high volatility of context in this environment. In the following a few examples of different approaches of contextbased recommender systems in a mobile environment are described. Woerndl et al. [21] describe recommendation of mobile applications to users based on what other users have installed in a similar context. Context-dependent information is recommended to the user, e.g. services of Real Madrid are proposed to the user when he walks in the vicinity of the Bernabeu stadium. Chen [22] discusses a context-aware recommendation system that predicts the user’s preferences on past experiences of like-minded users in “tourist activi534
But to let this vision of user-generated mobile services with (a) easy creation, (c) semantic search and context-based recommendation, (b) security and trust, and (d) revenue sharing become true, a number of requirements must be fulfilled by a platform in order to have chances for success. These requirements are: • Easy mobile service creation: Non-technical users should be able to create their own mobile services on their mobile devices. • Easy mobile service deployment: A created service should be more or less automatically deployable. • Easy service discovery and usage: It should be easy to find and use (potentially short-lived) services offered by other users. The corresponding search scenarios differ a lot from traditional approaches due to situational, location- and context-aware search and due to recommender approaches that are more and more converging. Moreover, the huge number of mobile services along with their potential short lifetime requires new approaches to capture information about services in the service lifecycle. • Security and privacy: Private and sensitive data of the user must be stored securely preventing unauthorized access in order both to guarantee the integrity of the entire system as well as to protect the privacy of the user. For access to services, mutual authentication mechanisms are needed. Moreover, protocols for secure communication between mobile devices and remote servers have to be in place. • Trustworthiness of users: Even though trust is already an important issue in conventional service scenarios, it is even more crucial when realizing the super prosumer concept in the context of community platforms. Authenticity of users and traceability in the case of fraud is important in order to prevent criminals from creeping in communities. • Identity management: Presumably, a user generated mobile service will be mashup of a number of existing services, e.g. a map service, a photo gallery service, a social network, etc., each one requiring an authentication. Therefore, an identity management system must be in place. Its usage is required to be ubiquitous and comfortable. It must, e.g., not enforce the user to have in mind all his username-password pairs, neither to type them in on a mobile keyboard. On the other hand, it must be possible to use different identities for the various services which cannot be linked. The user may even want to use different identities for the same service, e.g., in order to separate business contacts from private contacts in a social network. • Service Composition: The above mentioned mechanisms related to service creation, security, privacy, and trust must be available as service components that can be integrated via standard interfaces into user-generated services. • Making business and supporting revenue sharing: A platform with accounting and revenue sharing functionality should be built that enables a synergistic ecosystem that benefits all involved parties. One aspect of this
text in a SIM card. The SCWS can provide static content like HTML pages or media files as well as dynamic content. The content can easily be accessed, for instance from mobile phone Internet browsers. For today’s Java Card 2.2 platforms, the OMA has specified a SCWS including an interface for remote administration [29]. It will be adapted for upcoming techniques like high speed interface or TCP-enabled smart cards. The SCWS provides an extension programming interface similar to CGI [30] to deploy dynamic content. A real Java servlet container is not realized due to the limitation of the Java Card platform, e.g., the lack of multi-threading. G. Revenue Sharing Another important issue with user-generated content and services is how to make business and gain revenue. We believe that user-generated content and services should create value for their owners and everybody else in the ecosystem. Current business models in the fixed-line Internet domain offer content and services free of charge to the users, but require them to register themselves to a content and/or service platform. With this registration they provide some information about themselves and while using content and services they continuously update and extend their profile. This profile information is used by the providers to place advertisements on the Web pages, allowing them to earn money from the advertisers with their platform. But with such business models the user, or better prosumer, will not be able to get revenues for providing his content and services. Traditionally, the accounting and billing systems of the operators and Internet service providers have been geared towards billing the users, not to providing billing services to individual users. What is needed are fair user rewarding models where users receive a compensation for successful user-created content and services. This would support an innovative, fair and secure approach for mobile accounting and billing, adapted to the super prosumer ecosystem, allowing not only the users, but also service providers to directly gain revenues with user-generated content and services. On a technical level, we only know of one standard in the Web Services domain that provides an open interface for accounting and billing purposes, i.e., the Parlay X APIs for account management and payment [31] [32]. The operations offered by the Parlay X Payment API can build a basis to integrate charging mechanisms into user-generated mobile services. III.
REQUIREMENTS FOR USER-GENERATED MOBILE SERVICES
To use Internet-based user-generated content platforms like Facebook or YouTube, all which is required to contribute photos or videos is a camera or camcorder and basic computer skills [1]. So a first challenge is to make it equally easy for general users to create mobile services. All those people who can contribute to Facebook or YouTube should also be able to create mobile services.
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is to ensure that this platform itself creates value for its owner, i.e., the platform operator. Another is to guarantee that mobile service creators and providers are rewarded for their efforts. Even if the ecosystem is fuelled by advertising revenues, users who create successful services must be rewarded proportionally. Therefore adequate accounting, charging, and billing functions must be available. In addition to direct monetary revenues for service usage and the placement of advertisements, topic-bound analysis of dependencies between services, users, situations, etc., can be leveraged to discover new opportunities for making business: Exploring usage structures and activities which are bound to a certain kind of context can, e.g., be an added value for the operator and service providers. IV.
There is an enormous opportunity for exploiting the real market potential of this type of mobile micro services created, provided, and consumed by mobile users with only their mobile devices, e.g.: (a) Third party companies and even single (mobile) users can provide targeted services with great accuracy to special interest groups or communities based on their current context. (b) Network operators will benefit from network utilization as well as subscription services. (c) Prosumers can benefit from discounts offered by network operators for service deployment and usage. To give birth to such a new type of mobile usergenerated services (or micro services or uServices, resp.), the main technical objectives are: • Define a Service Description Language to permit the fixed-mobile service convergence in a wide sense: one worldwide user-powered content network. • Design and develop the service infrastructure for instantaneous, on-the-fly service creation, publication, provision, and consumption of contents from and to a mobile device, even for non-technical users. • Investigate in efficient context utilization means, such as automatic context-aware content generation and publication. • Generate a new set of resources for discovery, access and distance mobile-to-mobile communication on a distributed, volatile platform (with the service “not-alwayson” paradigm) to ease the service retrieval process by building on context-dependant filtering mechanisms. These filtering mechanisms shall be designed to support real-time scenarios in order to take account of the potential short life span of micro services. • Integrate the SIM into the architecture to provide basic services enhancing security, privacy, and trust. Sophisticated methods will be provided that ensure authenticity of all involved actors and traceability in the case of fraud. The smooth integration of identity management systems will increase the usability and hence the acceptance of security- and trust-enhancing methods.
THE USERVICE APPROACH
This section briefly describes the uService approach and highlights how to fulfill the requirements mentioned in the previous section. The uService project investigates the turn of mobile users into service super prosumers in order to benefit from the vast number of potential mobile services. These services can be consumed remotely by other users, in a simple way, with only their mobile devices. Mobile-to-mobile provision of this type of user-generated mobile services implies millions of potential sources with valuable information for the same amount of potential users. Due to the particular challenge of the mobile environment, where device resources, interaction possibilities and user attention are much more restricted compared to the fixed, traditional Web environment, uService proposes a new way to look at mobile information services in order to solve this problem and deliver services that all users are expecting – above all the non-technical users. In the uService project, this type of service is called micro service or uService. These services are small, sharply focused applications with their own graphical user interface, which allow users to obtain and provide information – like opinions, recommendation, location or speed – to fellow mobile users.
Figure 1: uService Architecture 536
custom services is only transmitted on the basis of trustworthy recommendation. Peter benefits from the uService platform and tools in a number of different ways: First, Peter is able to build a personal running diary application running on his mobile phone. A creation tool allows to combine building blocks through which Peter can, e.g., enter and manage profile information about his fitness plan, including fitness level, preferred running routes, etc. Additional building blocks are available to integrate different sensors. By this, the application is able to collect data about the routes he has run, his speed, pulse, and how much time he has spent running. Each time he is running, he is able to keep his profile up-to-date through the automated sensoring. The information stored on his mobile device allows Peter to use it afterwards to make his own statistics. Second, Peter can build a service to receive information from different trustworthy sources about, e.g., interesting running routes or other passionate runners in vicinity matching his own profile. He can integrate a service that announces commercial offers of professional trainers. With this information, Peter is able to plan a running trip in the evening, maybe even together with other members of the community that are recommended to him. Third, Peter is also able to build a service that provides information to other community members in a controlled manner. He is able to configure the service to determine when and whom information will be granted access this information. He can potentially share this information with other community members to find new running partners or to discuss with them. Last but not least, he may provide the collected data to his doctor to support medical checkups.
•
Open the SIM for hosting user-defined services where necessary and appropriate. Sample SIM-based services that will be realized during the project include user data management, service authentication, and secure transmission of sensitive data. • Integrate identity management systems into the architecture. Candidate technologies for identity management are Information Cards and OpenId. In any case, either the entire set of identities of a user or at least the access to these identities is protected by the SIM. • Promote new business models in the mobile world. The main objective is how to specify, configure, and implement fair accounting and monetary as well as potentially also non-monetary compensation among the involved actors. Figure 1 gives a rough overview of the uService architecture. The user as a mobile super prosumer can easily create services with an editor tool on his mobile device, publish them via a publisher component, and use them with a player. On the server side, the uService platform provides a repository for storing service templates and building blocks as well as a search engine for easy service discovery and usage. A publishing warehouse ensures security as well as accounting, charging, and billing. The security issues are handled by the identity management component, whereas charging and billing is done by the Accounting & Billing component. In addition, the Accounting & Billing component is analyzing the network traffic for mediation and accounting purposes. V.
URUN – AN APPLICATION EXAMPLE
uService creates an infrastructure for provision and consumption of different kinds of service applications. As one example, the project aims at applying the uService architecture for services from the health care and prevention realm. The ad-hoc provision of health-related information requires specific attention in terms of data security while at the same time allowing for immediate benefits for the user. Studies have proven that 30 minutes of physical activity each day is one of the most important enablers for physical well-being at the age of 40 and above. Thus, many frequent business travelers like to stick to their fitness programs, e.g., running, in order to stay in shape. A commonly perceived issue is the lack of information about appropriate locations and fitness partners in foreign cities and countries. Imagine the following scenario called uRun as one of several application examples (cf. Figure 2): Peter is a passionate runner and a frequent business traveler. When travelling for his job, he often gets to places he is not yet familiar with. Finding an adequate route for running is often difficult in such cases. Here, the new uService platform is very helpful. Besides other features, the uService platform and tools allow Peter for creating his own custom mobile applications for (a) gathering data from different sources, (b) making this information accessible for others in a controlled manner, and (c) getting in touch with like-minded people or professional fitness service providers. Peter does not have to be afraid about security and privacy issues, as all information provided to others through his
Figure 2: uRun Scenario The above mentioned scenario uRun allows building virtual social communities with inherent support for real physical meetings. Assuming that the information provided can be automatically filtered in real-time by other trusted community members in the user’s vicinity, the user will be able to find new partners matching his or her sporting interests wherever
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he or she is. One can go to a different city and find via GPS coordinates of other peoples’ mobile devices, who is running at defined times. One can publish own routes for others who might be new to the area and would be able to find commercial offers of, e.g., running coaches, nearby. VI.
[10] LarKC: The Large Knowledge Collider, STI Innsbruck, Austria. URL: http://www.larkc.eu [11] ORDI SG – Ontology Representation and Data Integration, Ontotext AD, Sofia, Bulgaria. URL: http://www.ontotext.com/ordi/ [12] SWSE – Semantic Web Search Engine. URL: http://swse.org [13] W3C, “Semantic Annotations for WSDL and XML Schema”, W3C Recommendation, 2007. URL: http://www.w3.org/TR/sawsdl/ [14] Seekda GmbH, Innsbruck, Austria. URL: http://www.seekda.com [15] WSMO Working Drafts, Web Service Modeling Ontology. URL: http://www.wsmo.org/TR/ [16] W3C, “OWL-S: Semantic Markup for Web Services”, W3C Member Submission, 2004. URL: http://www.w3.org/Submission/OWL-S/ [17] P. Resnick, N. Iakovou, M. Sushak, P. Bergstrom, J. Riedl, “GroupLens: An Open Architecture for Collaborative Filtering of Netnews”. In: Proceedings of the ACM 1994 Computer Supported Cooperative Work Conference, Chapel Hill, NC, USA, pp. 175-186, 1994. [18] G. Salton, Automatic Text Processing: The Transformation, Analysis, and Retrieval of Information by Computer. Addison-Wesley, 1989. [19] A. K. Dey, G. D. Abowd, D. Salber, “A Conceptual Framework and a Toolkit for Supporting the Rapid Prototyping of Context-aware Applications”. Human Computer Interaction Journal, Volume 16, pp. 97166, 2001. [20] M. Baldauf, S. Dustdar,, F. Rosenberg, “A Survey on Context Aware Systems”. International Journal of Ad Hoc and Ubiquitous Computing, Volume 2 (4), pp. 263-277, 2007. [21] W. Woerndl, C. Schueller, R. Wojtech, “A Hybrid Recommender System for Context-aware Recommendations of Mobile Applications”. In: Proceedings of the IEEE 3rd International Workshop on Web Personalisation, Recommender Systems and Intelligent User Interfaces (WPRSIUI'07), Istanbul, Turkey, 2007. [22] A. Chen, “Context-aware collaborative filtering system: predicting the user's preferences in ubiquitous computing”. In: Proceedings of the 2005 Conference on Human Factors in Computing Systems (CHI 2005), Portland, OR, USA, April 2005. [23] M. van Setten, S. Pokraev, J. Koolwaaij, “Context-Aware Recommendations in the Mobile Tourist Application COMPASS”. In: Third International Conference on Adaptive Hypermedia and Adaptive Web-Based Systems (AH 2004), Eindhoven, The Netherlands. Lecture Notes in Computer Science, Volume 3137, pp. 235-244, 2004. [24] Y. Zhiwen, Z. Xingshe, Z. Daqing, C.-Y. Chin, X. Wang, M. Ji, “Supporting Context-Aware Media Recommendations for Smart Phones”. Pervasive Computing, IEEE, Volume 5, Issue 3, pp. 68-75, 2006. [25] OASIS, “Web Services Security: SOAP Message Security 1.1 (WSSecurity)”, OASIS Standard Specification, February 2006. [26] OpenID Foundation, San Ramon, CA, USA. URL: http://openid.net [27] V. Bertocci, G. Serack, C. Baker, Understanding Windows CardSpace: An Introduction to the Concepts and Challenges of Digital Identities. Addison-Wesley, December 2007. [28] Java Card Technology, Sun Microsystems, Inc., Santa Clara, CA, USA. URL: http://java.sun.com/javacard/ [29] The Common Gateway Interface, National Center for Supercomputing Applications, University of Illinois at Urbana, IL, USA. URL: http://hoohoo.ncsa.uiuc.edu/cgi/ [30] OMA Smartcard Web Server V1.0, Open Mobile Alliance. URL: http://www.openmobilealliance.com/technical/release_program/scws _v1_0.aspx [31] 3GPP, “Open Service Access (OSA), Parlay X Web Services, Part 7: Account Management (Release 8)”. Technical Specification TS 29.199-7 V8.1.0, September 2009. [32] 3GPP. “Open Service Access (OSA), Parlay X Web Services, Part 6: Payment (Release 8)”. Technical Specification TS 29.199-6 V8.1.0, September 2009.
CONCLUSION AND OUTLOOK
The approach described in this article is based on the vision that the next generation of mobile services is going to be created by end-users. They will become mobile “super prosumers”, i.e., producers, providers, and consumers of mobile content and services. The state of the art in mobile services has been outlined and requirements to let this vision come true have been identified. Based on this evaluation, a new approach – the uService approach – that fulfills the requirements has been presented. While still a concept, this approach considers both the technical as well as the business perspective. The ITEA2 project uService is running until end of 2011. After the conceptual phase, the consortium will develop a prototypical platform and tools for easy creation and recommendationbased discovery before conducting field tests, one of which is the uRun scenario described in this article. The intended field tests are an ideal means to investigate the potential for exploiting micro services, through which mobile users can provide targeted services to trusted community members based on their current context. ACKNOWLEDGMENTS This work has been funded in part by the Federal Ministry of Education and Research (BMBF) under contract no. 01IS09020A-F (project uService) and is supported by the EUREKA cluster programme ITEA2 (http://www.itea2.org). We would like to thank all partners of the international uService project (http://www.uservice-itea2.eu). This article is based on the full project proposal submitted to ITEA2. REFERENCES [1]
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