Summer SOC July 2 nd – July 7 th Aniketos platform: Design of a trustworthy composite service 1

Summer SOC 2012 A service provider wants to offer a service that takes in input the geographical position of a user and shows in a webpage a set of information: A map showing the position Weather information Point of interests in the surroundings The service provider wants the service to be trustworthy, so he asks the service designer to exploit the tools made available through the Aniketos platform 2 Reference scenario for the demo

Summer SOC 2012 The trustworthiness value is evaluated by the Trustworthiness Prediction module and is a combination of: Cognitive trust of the user, based on the service and service provider reputation. Non-cognitive trust, based on objective and measurable properties of the service such as QoS attributes (reliability, performance, availability) 3 About trustworthiness in Aniketos…

Summer SOC Service Composition Framework (SCF) The SCF is a design time module available in the Aniketos environment allowing a service designer to build executable composition plans To use the framework the service designer must be authenticated

Summer SOC SCF: get started with BPMN modelling Once authenticated, the service designer can start the BPMN modelling

Summer SOC BPMN model of InfoService From the description of the service in terms of functionality, the service designer decides to use different atomic services and compose them according to the BPMN drafted in the SCF editor

Summer SOC 2012 The service designer is in charge of designing a composite service with a specific requirement on trusthworthiness value The trustworthiness requirement is expressed as a consumer policy written in ConSpec grammar The file location is included in an extensionElements tag in the xml representing the BPMN 7 BMPN annotated with trustworthiness requirement

Summer SOC 2012 An excerpt of the resulting xml for the annotated BPMN is shown below: 8 Annotated BPMN

Summer SOC 2012 To make the composition plans the SCF has to bind real web services to the service tasks in the BPMN The binding process entails: Service discovery using the ServiceType as search filter The SCF shows the operations offered by the web services matching the request based on the ServiceType Selection of the specific operation the service designer wants to use in order to compose the InfoService If the same operation is offered by different atomic services the service designer will see just one operation 9 Service discovery and selection of the service operation

Summer SOC Discovery and selection: GeoCoding example (1/2)

Summer SOC 2012 and selects getCoordinates ( ) 11 Discovery and selection: GeoCoding example (2/2) The service designer discovers operations offered by GeoCoding type services ( ) 1 2 The service designer isn’t aware of how many web services offer that operation, it’s the SCF which will bind the different services to the service task when making composition plans

Summer SOC 2012 Creation of composition plans 12 Once the service designer has selected an operation for each service task the SCF is ready to create the composition plans When the service designer clicks on “Create composition plans” button, the SCF shows a set of functionally valid composition plans

Summer SOC 2012 The SCF has created 12 composition plans: this is explained by the number of web services offering the same operation: Geocoding type: bound to 2 web services PointOfInterest type: bound to 3 web services WeatherForecast type: bound to 1 web services Map type: bound to 2 web services WebPageInfoCollector type: bound to 1 web services Thus the number of composition plans is 2 X 3 X 1 X 2 X 1 = Composition plans created by the SCF

Summer SOC 2012 The composition plans ensure functionality but do not consider the trustworthiness requirement The composition plans have to be checked against the requirements specified for the trustworthiness value This check is performed by the Secure Composition Planner Module which receives the composition plans from the SCF and returns those ones that fulfill the trustworthiness requirement 14 Selection of trustworthy composition plans

Summer SOC 2012 The SCPM invokes the Trustworthiness prediction module to evaluate the trustworthiness value for the set of composition plans received from the SCF The trustworthiness value of the composite service is evaluated using the weakest link principle The Trustworthiness module evaluates the trustworthiness value for each service taking part in the composition The lowest value is returned as the trustworthiness value of the composite service 15 Trustworthiness prediction for composite services

Summer SOC 2012 When the service designer clicks on “Verify All” button the SCPM selects the composition plans that fulfils the trustworthiness requirement 16 Trustworthy composite services In order to visualize the Trustworthiness value of the composition plans the service designer selects “Order By” Trustworthiness and clicks on “Order/Rank” button

Summer SOC Last steps: upload and deploy The service designer selects one of the trustworthy composition plans and can Upload the BPMN to an Activiti Engine Deploy it to a web application server

Summer SOC