Context-aware mobile Collaboration Web services

(in ad-hoc and infrastructure based environments)

Towards a PhD

Christoph DornDistributed Systems Group

Institute of Information Systemshttp://www.infosys.tuwien.ac.at/Staff/dorn/

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Overview

Overview Challenges Past and Current Research Activities Related Work Future Steps

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Research Scope – inContext Project

Infrastructure

Infrastructure

Supporting Relevance-based Collaboration Services:

anytime,anywhere,any device,anybody

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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

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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

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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

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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?

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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

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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

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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 ;-)

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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

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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

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Context Hierarchies (1)

Basic idea: structure context information according to levels of detail

Location Presence Activity Team Status

Country Top Status Environment Anybody

City Substatus Subenvironment Roles

Street Activity Project Numbers

Number Location Artefact People

Floor Task

Room

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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)

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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.

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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

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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

WS Container (OSGi)

Context System

Hierarchy Adapter

Context Publish/

Subscribe

Platform Context Manager

WS WS WS

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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

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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

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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

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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]

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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

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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

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Discussion

Any Questions?

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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-1841-2006-36, (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, 2005. AINA, Mar. 2005, p.189-192

[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.251-270

[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

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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, 2004. Proceedings. Jul. 2004, p.350-357

[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.140-144

[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.40-48

[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.222-231

[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. 2003

[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.741-746

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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, 2004. VTC 2004. (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. (2004) 48–61

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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, 2004. PerCom 2004. (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)