Context-aware mobile Collaboration Web services (in ad-hoc and infrastructure based environments) Towards a PhD Christoph Dorn Distributed Systems Group Institute of Information Systems

2 Overview  Overview  Challenges  Past and Current Research Activities  Related Work  Future Steps

3 Research Scope – inContext Project Supporting Relevance-based Collaboration Services: anytime, anywhere, any device, anybody

4 Overview (1) Context  Context Definition:  “[... ] any information that can be used to characterize the situation of an entity. An entity is a person, place, or object that is considered relevant to the interaction between a user and an application, including the user and applications themselves” [DeyAbowd2000]  Examples  Location, Presence, Device Capabilities, User Preferences, Patterns, Calendar, Team structure  Context-aware  Any software entity that uses context information to improve its purpose

5 Overview (2) Mobility  Mobile Web Services – 3 scenarios  S1: requestor is mobile and service static  S2: requestor is static and provider mobile  S3: requestor and provider are mobile

6 Overview (3) Environment Ad hoc vs  MANETs (Mobile Adhoc NETworks)  Provide most underlying services by devices  Routing  Discovery  Security  P2P Infrastructure  Fixed networks  Always on  Reliable/stable  Underlying services provided  Client/Server

7 Challenges (1) Context  Context is most useful in dynamic, mobile environments. But what is the relevant information in various situations?  Mobility results in continuous updates of context information. How can we efficiently manage this?  How can we share context?  How do we handle uncertainty of context information?  How do we ensure privacy control and management of context information?  How do we reach a common understanding of implications and semantics of (shared) context information?

8 Challenges (2) Mobility  Assumptions about the where and when and who of service usage in mobile environments are a lot harder to make than in fixed environments – usage patterns (time, location, availability, device characteristics)  Resource restrictions  Processing power (XML parsing)  Main memory (XML parsing, DOM)  Connectivity costs (low bandwidth and/or high usage costs)  Display size  Input types  Connectivity - devices/services:  appear  reconfigure  move around  disappear

9 Challenges (3) Technology  Devices  PDA, Smartphones, TabletPC, Laptops, (Servers)  Communication Capabilities  WLAN, Bluetooth, GPRS, UMTS, WIMAX, HSDPA,  Development support: IDEs, Programming Languages, Containers, Tools  Java(EE, SE, ME), OSGi, Symbian/C++, .NET (Compact Framework) C#  Web service support:  mostly only client side,  WS-* support besides SOAP and WSDL

10 Challenges (4) Collaboration  “different team forms (nimble, virtual, mobile/nomadic)  switch between user context and team contexts.  Provide information to teams to allow team awareness.  Relevant pervasive collaboration services: documents, calendar, communication means, notifications, project status, team awareness  Nimble/Virtual/Mobile teams forms require adapted mechanisms  Member of varied team forms simultaneously” (stolen from CWE 2006 talk when Schahram was not looking ;-)

11 Active Research  Current Papers:  Sharing Hierarchical Context for Mobile Web Services (submitted to DPDJ, in review)  Personal Context Network (work in progress)  Concepts  Context Hierarchies  Context sharing based on hierarchies (CASQL) Context Access control, Subscription and Query Language  Context Relevance / Dominance

12 Service Oriented Context  Definition by Dey and Abowd [Dey+Abowd2000] extended to fit a service-oriented environment: “Context is any information that can be used to characterize the situation of a service that participates in fulfilling a user’s task. Thus, context encompasses all information that is considered relevant to the interaction between a user and a service as well as communication in-between services.” [DornDustdar2006]  Context definition explicitly extended to cover service composition and adaptation as context is applied at the user, role, and service level

13 Context Hierarchies (1)  Basic idea: structure context information according to levels of detail LocationPresenceActivityTeam Status CountryTop StatusEnvironmentAnybody CitySubstatusSubenvironmentRoles StreetActivityProjectNumbers NumberLocationArtefactPeople FloorTask Room

14 Context Hierarchies (2)  Tree structure using XML:  Hierarchy (Id, Name, Description, Entity)  Level (Id, Name, Description, Parent Level)  Value (Name, Value, Timestamp, Confidence, Source)  Detailed Value: Value further structured by means of XML (specific to domain, hierarchy, level, and value)

15 Context Hierarchies (3) - Benefit  Network load:  Sharing limited to relevant detail level (  reduced strain on bandwidth as changes on lower/finer levels are not propagated)  Privacy control mechanism:  information might be necessary, won’t disclose fine grained but adequate level. More detailed only on demand or required.  Confidence:  uncertain facts at fine level can be compensated more reliable facts at higher levels  Relevance:  Basis for defining relevant context information under certain conditions.

16 Context Sharing (1) - Context Access control, Subscription, and Query Language  XML-based (XPath, XQuery, XSLT)  Subscription defined as XQuery statements  Access policies defined as XPath statements  Notification event to subscription matching based on XPath

17 Context Sharing (2)  Context Sharing Architecture components  Context System (Blackbox) (CSB) – provides context information  Hierarchy Adapter (HA) – maps hierarchies to context model as used by the CSB  Context Publish/Subscribe (CPS) – subscribes at remote peers, receives updates and vice versa (CASQL)  Platform Context Manager (PCM) – provides service roles for access mechanism

18 Context Relevance / Dominance & Web service interaction-based access  Condition-based context relevance  e.g., If I’m at work, my activity status is dominant/more relevant than my presence status.  If I’m at home, however, it’s vice versa  Web service interaction-based access to context  composition, requestor, provider  interface, identical, remote, local  invocation start, invocation end, composition start, composition end

19 Current research activities  Extending the concepts of hierarchical context sharing  Analysis and improvement of hierarchy handling, creation/mapping, definition, and structure  Actual Implementation of the Context Sharing Architecture in OSGi (Knopflerfish)  Complete definition of four concrete hierarchies (introduced above) on top of a collaboration (context) model  Basis for the Personal Context Network

20 Related Work (1) Mobile WS  Connectivity  Zahreddine & Mahmoud [ZM2005], Maamar et al. [Maa+2004], Chakraborty et al. [Cha+2002] (agents)  Friedman [Fri2002] (caching), Pilioura et al. [Pil+2003] (proxy), Lee & Fox [LF2004] (reliable messaging)  Discovery  GSD: Chakraborty et al. [Cha+2003] (group based)  WizNet: Dustdar & Treiber [DT2004], Self-serv: Benatallah et al. [Ben+2003] (communities)  Selection  Sen et al. [Sen+2004], Doulkeridis et al. [Dou+2003] (prediction: where, when)  Composition (agents, intermediary)  Lee et al. [Lee+2005] intermediary

21 Related Work (2) Context  Sharing  Web Service Context [WS-Context2004]  Service Oriented Context-Aware Middleware (SOCAM) [Gu+2004]  Context Broker Architecture (CoBrA) [Chen+2003]  Solar: An open platform for context-aware mobile applications [ChenKotz2002]  Service platform for mobile context-aware applications [Costa+2004]  [BiegelCahill2004] Sentient Component Model  Granularity / Context Hierarchies  Context Awareness for Group Interaction Support [Ferscha+2004] – symbolic location hierarchy  Context Management in Heterogeneous, Evolving Ubiquitous Environments [daRochaEndler2006]

22  Short term:  Finish paper(s) on context granularity, sharing and control including implementation  Research aspects of the Personal Context Network (temporal sharing patterns, logical context sources, …)  Long term:  Focus on relevance criteria and modeling  Complete Personal Context Network  Finally:  Have a (small) set of tools to support context aware, relevance-based collaboration services for mobile (ad-hoc) networks Miracle here Future Steps

23 VitaLab Integration  Links to other projects/efforts/students:  Semantics (Context modeling): Alexander Urbanek  Workflow & Patterns: Martin Vasko, Robert Gombotz  Rule Engines: Florian Rosenberg  Mobile Web Services: Daniel Schall  Service Oriented Middleware: Martin Treiber

24 Discussion  Any Questions?

25 Resources (1) [DeyAbowd2000] Dey, A., Abowd, G.: Towards a better understanding of context and context-awareness. In: Workshop on the What, Who, Where, When and How of Context-Awareness at CHI 2000, (2000) [DornDustdar2006] Dorn, C., Dustdar, S.: Sharing Hierarchical Context for Mobile Web Service, Technical Report, Vienna University of Technology TUV , (April 2006) [ZM2005] Zahreddine, W. and Mahmoud, Q.H.: An agent-based approach to composite mobile Web services, 19th International Conference on Advanced Information Networking and Applications, AINA, Mar. 2005, p [Maa+2004] Maamar, Z., Sheng, Q.Z., and Benatallah, B.: On Composite Web Services Provisioning in an Environment of Fixed and Mobile Computing Resources, Information Technology and Management Journal, (5), 2004, p [Cha+2002] Chakraborty, D., Perich, F., Joshi, A., Finin, T., and Yesha, Y.: Middleware for Mobile Information Access, 5th International Workshop on Mobility in Databases and Distributed Systems (MDDS 2002), Sep.2002 [Fri2002] Friedman, R.: Caching web services in mobile ad-hoc networks: opportunities and challenges, POMC '02: Proceedings of the second ACM international workshop on Principles of mobile computing, 2002, p90-96

26 Resources (2) Mobile WS [LF2004] Lee, S. and Fox, G.: Wireless Reliable Messaging Protocol for Web Services (WS-WRM), IEEE International Conference on Web Services, Proceedings. Jul. 2004, p [Cha+2003] Chakraborty, D., Joshi, A., Yesha, Y. and Finin, T.: GSD: a novel group-based service discovery protocol for MANETS, 4th International Workshop on Mobile and Wireless Communications Network, 2002, p [DT2004] Dustdar S. and Treiber, M.: WiZNet - Integration of different Web service Registries, 2004, citeseer.ist.psu.edu/dustdar04wiznet.html [Ben+2003] Benatallah, B., Sheng, Q.Z., and Dumas, M.: The Self-Serv Environment for Web Service Composition, IEEE Internet Computing Journal, Jan/Feb 2003, p [Sen+2004] Sen, R., Handorean, R., Roman, G., and Hackmann, G,: Knowledge-driven interactions with services across ad hoc networks, ICSOC '04: Proceedings of the 2nd international conference on Service oriented computing, Nov. 2004, p [Dou+2003] Doulkeridis, C., Valavanis, E., and Vazirgiannis, M.: Towards a Context-Aware Service Directory, 29th International Conference on Very Large Data Bases (VLDB 2003), Sep [Lee+2005] Lee, W., Lee, K., Lee, S., and Lee, K.: An efficient framework for composite enabled mobile web services, The 7th International Conference on Advanced Communication Technology, 2005, ICACT, Feb. 2005, p

27 Resources (3) Context [WS-Context2004] Little, M., Newcomer, E., Pavlik, G.: Web Service Context Specification (WS-Context). OASIS. (2004) [Gu+2004] Gu, T., Pung, H.K., Zhang, D.Q.: A middleware for building context-aware mobile services. In: 59th Vehicular Technology Conference, VTC (2004) 2656–2660 [Chen+2003] Chen, H., Finin, T., Joshi, A.: An ontology for context- aware pervasive computing environments. Special Issue on Ontologies for Distributed Systems, Knowledge Engineering Review 18(3) (2003) 197–207 [ChenKotz2002] Chen, G., Kotz, D.: Solar: An open platform for context-aware mobile applications. In: First International Conference on Pervasive Computing (Short Paper). (2002) 41–47 [Costa+2004] Costa, P.D., Pires, L.F., van Sinderen, M., Filho, J.P.: Towards a service platform for mobile context-aware applications. In: 1st International Workshop on Ubiquitous Computing - IWUC (2004) 48–61

28 Resource (4) Context [BiegelCahill2004] Biegel, G., Cahill, V.: A framework for developing mobile, context-aware applications. In: Second IEEE Annual Conference on Pervasive Computing and Communications, PerCom (2004) 361–365 [Ferscha+2004] Ferscha, A., Holzmann, C., Oppl, S.: Context awareness for group interaction support. In: MobiWac ’04: Proceedings of the Second International Workshop on Mobility Management & Wireless Access Protocols, New York, NY, USA, ACM Press (2004) 88–97 [DaRochaEndler2006] da Rocha, R.C.A., Endler, M.: Context management in heterogeneous, evolving ubiquitous environments. IEEE Distributed Systems Online 7(4) (2006)