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A. Bucchiarone, Juan P. Galeotti / GT-VMT’08
Dynamic Software Architectures Verification using DynAlloy
Antonio BucchiaroneAntonio BucchiaroneIMT Graduate School of Lucca, ItalyIMT Graduate School of Lucca, Italy
andandISTI-CNR of Pisa, ItalyISTI-CNR of Pisa, Italy
and
Juan P. GaleottiUniversidad de Buenos Aires, ArgentinaUniversidad de Buenos Aires, Argentina
A. Bucchiarone, Juan P. Galeotti / GT-VMT’08
Agenda
Introduction Background QoS Model for Service Composition
A Front-End Application Queueing Model Service Composition Flow Models QoS Service Composition Algorithm
Related Work Conclusions and Future Work
A. Bucchiarone, Juan P. Galeotti / GT-VMT’08
Introduction
SOC is a promising means to integrate heterogeneous systems
Services from different providers can be integrated into a composite service
QoS of Data-Intensive applications Reliability Performance
Service description QoS dynamic composition
A. Bucchiarone, Juan P. Galeotti / GT-VMT’08
Background - I
Services (functionality) Context adaptive and intelligent user services Information services Intermediary services Location-based services
Services (technical protocols) Web Services Grid Services
“a service provides some useful functionality through a well defined interface and it is possible to combine them to produce useful “composite” services.”
A. Bucchiarone, Juan P. Galeotti / GT-VMT’08
Background - II
Services Composition Web Services
SOAP, WSDL and UDDI Orchestration (BPEL4WS) and Choreography (WS-CDL)
Grid Services To utilize the power of heterogeneous distribute
resources, computing resources, data storage systems, instruments, ..
Grid and Web Services are converging in the WSRF A series of specifications for performing grid
computing on top of web services
A. Bucchiarone, Juan P. Galeotti / GT-VMT’08
Background - III
Service Level Agreement (SLA) It complements a service description
language It defines the agreed performance
characteristics and the way to evaluate and measure them
A. Bucchiarone, Juan P. Galeotti / GT-VMT’08
QoS Model for Service Composition
Front-End application The actors and theirs main functionalities
Queueing Model For data-intensive applications
Services Composition Flow Models Types of services and basic relationships QoS parameters
QoS Service Composition Algorithm To compose services that have QoS
attributes
A. Bucchiarone, Juan P. Galeotti / GT-VMT’08
QoS Model for Service Composition Front-End application - I
“A system that is able to put together different services from various providers in order to construct and execute a data-intensive application”
Providers Companies distributed on
the net Customer
Client that wants execute a new application that satisfies some QoS characteristics
Front-End application System that realizes the
application
Front-EndApplication
Searching Services
QoS Algorithm
Customer
ServicesClassification
Providers
provide
OK
Execution
WorkflowDefinition
NOK
QoSInitialization
request
invoke
throwexception
ServiceDescription
ApplicationChosen
1
2
3
45
6
6.1
7.A
7.B
A. Bucchiarone, Juan P. Galeotti / GT-VMT’08
QoS Model for Service Composition Front-End application - II
Service Description (providers) QoS parameters for the service classification
Service Classification (front-end) It subdivides the services in classes based on their
description and QoS attributes Workflow definition (front-end)
Services composition structure Meta-workflow (data-flow, Pipeline)
Application Chosen (Customer) It choose the kind of application that he wants (data
mining, astronomy, traveling, tourism,..) QoS Inizialization (Customer)
max-cost of the service composition min-perf : medium departure time of each result in the
last node of the workflow QoS Algorithm (front-end)
QoS Services Composition Input: Workflow definition and QoS parameters Output: workflow in which the services are instanciated
(final application) Searching Services (front-end)
Search a service based on QoS parameters Execution Throw Exception
Front-EndApplication
Searching Services
QoS Algorithm
Customer
ServicesClassification
Providers
provide
OK
Execution
WorkflowDefinition
NOK
QoSInitialization
request
invoke
throwexception
ServiceDescription
ApplicationChosen
1
2
3
45
6
6.1
7.A
7.B
A. Bucchiarone, Juan P. Galeotti / GT-VMT’08
QoS Model for Service Composition Queueing Model
From: L. Kleinrock, “Queueing Systems, Vol. I: Theory,” The arrival process of customers (Ta) The service times (Ts) The service discipline
Fifo Lifo Random Processor sharing
The queue occupation rate or server utilization ρ = Ts / Ta
Our model: Data-Flow Our target: ρ < 1
A. Bucchiarone, Juan P. Galeotti / GT-VMT’08
QoS Model for Service Composition Services Composition Flow
Models - I
Types of Services
Relationships (DAG) Data-flow Or Pipeline
A. Bucchiarone, Juan P. Galeotti / GT-VMT’08
QoS Model for Service Composition Services Composition Flow
Models - II
Goal: build an application from an automatic composition of services
QoS parameters Intuitive Easy to measure
A. Bucchiarone, Juan P. Galeotti / GT-VMT’08
QoS Model for Service Composition QoS Service Composition
Algorithm
Input Workflow definition
of the service composition, and QoS attributes
Output Workflow
instantiated with real services satisfying QoS attributes
A. Bucchiarone, Juan P. Galeotti / GT-VMT’08
Related Work
SWORD project Rule-based Web Services composition Offline composition (not at run time)
FUSION framework Web Services composition according users satisfaction criteria Run time composition
WebQ framework Adaptive management of Web services QoS selection criterion only considers service load and makes only
local decisions EFlow
A platform for the specification, enactment and management of composite services (graphs)
The graphs may include service, decision and event nodes GSFL (Grid Service Flow Language)
Grid Services composition
A. Bucchiarone, Juan P. Galeotti / GT-VMT’08
Conclusions
A front-end application in order to develop data-intensive applications starting from services developed by different owners
QoS composition algorithm
Open Points To enrich composition model with more complex
workflows To enrich QoS composition algorithm considering the
transmission time parameter that can be variable To implement the front-end application with the QoS
composition algorithm in order to use it in a real case-study
A. Bucchiarone, Juan P. Galeotti / GT-VMT’08
Thank you for your attention!
Antonio BucchiaroneAntonio Bucchiarone
PhD Student – IMT Graduate School PhD Student – IMT Graduate School Piazza S. Ponziano 6, 55100 Lucca (Italy)Piazza S. Ponziano 6, 55100 Lucca (Italy)
and
Luigi PrestiLuigi Presti
IBM Software Group – Tivoli Rome Lab IBM Software Group – Tivoli Rome Lab Via Sciangai 53, 00144 Rome (Italy)Via Sciangai 53, 00144 Rome (Italy)
