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1/24 21/05/2009ContextServ at ICSE 2009 ContextServ: A Platform for Rapid and Flexible Development of Context- Aware Web Services Quan Z. Sheng, Sam Pohlenz,

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Presentation on theme: "1/24 21/05/2009ContextServ at ICSE 2009 ContextServ: A Platform for Rapid and Flexible Development of Context- Aware Web Services Quan Z. Sheng, Sam Pohlenz,"— Presentation transcript:

1 1/24 21/05/2009ContextServ at ICSE 2009 ContextServ: A Platform for Rapid and Flexible Development of Context- Aware Web Services Quan Z. Sheng, Sam Pohlenz, Jian Yu, Hoi S. Wong, Anne H.H. Ngu, and Zakaria Maamar School of Computer Science The University of Adelaide

2 2/24 21/05/2009ContextServ at ICSE 2009 Agenda Context-Aware Web Services (CASs) –Challenges in Developing CASs ContextServ Platform –Architecture –Context Provisioning –CAS Modeling –Model Transformation –Example CASs

3 3/24 21/05/2009ContextServ at ICSE 2009 Context-Aware Web Services Context awareness: the capability of being aware of its physical environment or situation (context) and responding proactively and intelligently based on such awareness One of the most important trends in computing that holds the potential to make our daily lives more productive, convenient, and enjoyable Web services: a major technology to implement loosely- coupled business processes and perform application integration A flourishing research and development area in the last decade Context-aware Web service (CAS): make Web services more personalized, adaptive, and intelligent Vision of “The Future Internet”: an Internet of services where services are ubiquitous (

4 4/24 21/05/2009ContextServ at ICSE 2009 Attraction Search Service: An Example CAS Attractions Search Service (ASS) Recommend attractions according to user’s location, weather, language: 1) If weather is bad (harsh weather): indoor attractions 2) If description is not in preferred lang.: translate to the preferred lang. Subscribe personal preferences (e.g., preferred attractions, language) Harsh weather is defined as: (temperature>40°C or temperature 80%

5 5/24 21/05/2009ContextServ at ICSE 2009 To Date, CASs Are Still Hard to Build… Current Web service standards (e.g., SOAP, UDDI, WSDL) are not sufficient for describing and handling context information Context provisioning is not trivial –Heterogeneity of context providers –Quality of context –Dynamic context environments (e.g., unavailability, quality change) –Context aggregation Lack of generic approach for formalizing the CAS development –Contexts management is implemented in an ad-hoc manner –Evolution of Web service platforms Developing CASs is cumbersome, error-prone, and time- consuming, especially when these CASs are complex.

6 6/24 21/05/2009ContextServ at ICSE 2009 ContextServ Project ContextServ is a research project aiming at rapid and flexible development of context-aware Web services (CASs) Sponsored by Australian Research Council (ARC) ContextServ provides a platform for model-driven development of CASs Offers design flexibility by separating the modeling of context and context-awareness from service components Uses high-level, visual modeling language (ContextUML) Offers a set of automated tools for generating and deploying executable implementations of CASs Eases development and maintenance of CASs; reduces development costs

7 7/24 21/05/2009ContextServ at ICSE 2009 Model-Driven Development Platform Independent Models Model Transformation Target Executable Platforms Transformation knowledge Transformer Implementation of platform 1 Implementation of platform 2 Implementation of platform 3 Models Software systems are specified in platform independent models (PIMs) by adopting high-level abstractions (languages) PIMs are then (semi)automatically transformed into platform specific models (PSMs) using transformation tools); A PIM can be transformed into different executable platforms (i.e., PSMs) Improves the productivity and quality; eases the system maintenance and evolution; enhances the portability.

8 8/24 21/05/2009ContextServ at ICSE 2009 ContextUML Service Operation Message Part CAObject CAMechanism Context ContextBinding ContextTriggering ContextConstraint Action ContextService Context Community AtomicContext CompositeContext inputoutput 0..1 1 1..* part 0..* * * * member * * 1..* * * * * MechanismAssignment SourceAssignment Context Modeling Context-Awareness Modeling ContextSource Service Modeling ContextUML: A UML-Based Modeling Language for Model-Driven Context-Aware Web Service Development. Q.Z.Sheng and B. Benatallah. ICMB05

9 9/24 21/05/2009ContextServ at ICSE 2009 ContextServ Architecture ContextUML model CAS interface Service Developer WSDL specification of service Web service registry (UDDI) Execution engine (e.g., BPWS4J) Web server Transform to WSDL Publish service to registry Service consumer Deploy service Transform service model to executable specification Configure and run service at the engine Invoke service Search service Bind to service implementation Specify service interface Specify context provisioning Specify context-aware Web service in ContextUML Context Context Manager communitycomposition ContextUML Modeler Executable specification of service (e.g., BPEL) RubyMDA Transformer 12 3

10 10/24 21/05/2009ContextServ at ICSE 2009 1. Context Management ContextServ distinguishes between atomic contexts and composite contexts Atomic contexts: low-level contexts, directly provided by context sources –e.g., temperature, rainlikelihood Composite contexts: high-level contexts, no direct providers, aggregate multiple atomic or composite contexts –e.g., harshWeather –Improve the modeling power of context information to CAS designers ContextContextSource ContextService Context Community AtomicContext CompositeContext * * * member * * 1..* SourceAssignment … ContextServ exploits context community to address the heterogeneous and dynamic context information Dynamic provisioning of optimal context information (QoC based selection)

11 11/24 21/05/2009ContextServ at ICSE 2009 Interface

12 12/24 21/05/2009ContextServ at ICSE 2009 Specify Atomic Context Specify details of the context provider

13 13/24 21/05/2009ContextServ at ICSE 2009 Specify Composite Context Composite contexts are specified using statechart, which are then translated to SCXML, a markup language for statechart, and executed in a SCXML execution engine such as Commons SCXML

14 14/24 21/05/2009ContextServ at ICSE 2009 Specify Context Community Context providers register to a context community (next slide) Dynamic and optimal context provider selection: We identify a set of QoC (Quality of Context) attributes such as precision, refresh-rate, trustworthiness etc The selection is based on a utility function calculate the value scale the value (for positive context) calculate the value scale the value (for negative context) rr(provider)

15 15/24 21/05/2009ContextServ at ICSE 2009 Context Provider Registration specify member details specify supported contexts

16 16/24 21/05/2009ContextServ at ICSE 2009 2. ContextUML Modeler ContextServ relies on ContextUML, a UML-based modeling language that provides high-level, visual constructs for specifying CASs ContextUML abstracts two context awareness mechanisms, context binding and context triggering Context binding: automatic binding of contexts to context-aware objects –Mapping between a context and context-aware object (e.g., input parameter of the service) Context triggering: contextual adaptation where services can be automatically executed or modified based on context information –If weather is harsh, only recommend indoor attractions CAObject CAMechanism ContextBinding ContextTriggering ContextConstraint Action * 1..* * * MechanismAssignment * 1..*

17 17/24 21/05/2009ContextServ at ICSE 2009 The ContextUML modeler offers a visual interface for specifying CASs using ContextUML. We extended ArgoUML ( by developing a new ContextUML diagram, which implements all the abstract syntax of ContextUML. Services represented in ContextUML diagrams are exported as XMI files for later processing. ContextUML diagram ContextUML abstracts

18 18/24 21/05/2009ContextServ at ICSE 2009 3. Transformation and Deployment ContextServ automatically transforms CASs specified in ContextUML to executable Web service codes in BPEL, which is realized by a transformer The transformer was developed in Ruby programming language (RubyGems 1.0.1,, thus the name of RubyMDA transformer A WSDL is also automatically generated CASs are then deployed to the JBoss Application Server, which includes a BPEL execution engine, jBPM-BPEL1.1 XML2UMLUML2CAS CAS:BPEL CAS:JBoss XMI Service.bpel Service.wsdl build.xml bpel-definition.xml bpel-application.xml wscompile.xml web.xml webservices.xml Input Transformer Generator Output

19 19/24 21/05/2009ContextServ at ICSE 2009 Transformation Rules RubyMDA transformer exploits the model transformation rules, which are mappings between ContextUML stereotypes and BPEL elements, for the transformation ContextUMLBPEL > > > > > > > part attribute in >

20 20/24 21/05/2009ContextServ at ICSE 2009 Transformation Rules in XML Builder For BPEL generation For WSDL generation

21 21/24 21/05/2009ContextServ at ICSE 2009

22 22/24 21/05/2009ContextServ at ICSE 2009 Generated BPEL code Generated WSDL code

23 23/24 21/05/2009ContextServ at ICSE 2009 CASs Developed from ContextServ CAS applications are available online: software.html A movie is available which captures the whole process in developing this CAS using ContextServ platform

24 24/24 21/05/2009ContextServ at ICSE 2009 Thank you for your interest to ContextServ Project More information on ContextServ can be found from Other related research information can be found from School of Computer Science The University of Adelaide

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