A Model-Based Synthesis Process for Choreography Realizability

Transcription

1 Vanessa Zahorian & Kristin Long in Divertimento N 15 - Photo (c) Erik Tomasson A Model-Based Synthesis Process for Choreography Realizability Marco Autili Enforcement marco.autili@univaq.it GSSi 2013 November 27th L Aquila - Italy Template v10

2 well-founded reference paradigm for the Future Internet Service-Oriented Computing (SOC) is now largely accepted as a computing Setting the context The Future Internet in service-oriented system development envisions an ultra large number of diverse service providers and consumers that can be composed to fit users' needs It is difficult (if not impossible) to coordinate an ultra large number of service providers and consumers using centralized approaches The trend is to build modern applications by reusing and assembling services in a distributed way, rather than realizing standalone, centralized (monolithic) programs 2

3 Choreographies are an emergent Service Engineering (SE) approach to compose together and coordinate services in a distributed Troisième way niveau Choreographies? A choreography formalizes the way business participants coordinate their external interactions The focus is not on orchestrations of the work performed within (a composition of) participants, but rather on the exchange of messages between them 3

4 Orchestration VS Choreography Cliquez Orchestration pour modifier les styles du texte du a local centralized view from the perspective of one participant Choreography coordination Quatrième niveau from a global multi-participant perspective, Cinquième niveau albeit without a central controller 4

5 Choreography Deuxième Service choreography niveau is a form of service Troisième composition niveau in which the interaction protocol between several Quatrième partner niveauservices is defined from a global perspective Choreography The intuition underlying the notion of service choreography can be summarized as follows: Dancers dance following a global scenario without a single point of control" 5

6 Orchestration VS Choreography Cliquez pour modifier les styles du texte du Service choreographies will contribute to the SOC vision within the Future Internet only if automatically supported by suitable design and development environments, as well as a set of infrastructural services Choreography Orchestration 6

7 The problems usually addressed when considering a choreography-based specification of the system to be realized Deuxième are niveau Realizability check The usual problems whether a choreography can be realized by implementing each participant as specified by the role to be played Conformance check whether the global interaction of a set of services, discovered as suitable participants, satisfies the choreography or not 7

8 However, when the goal is to actually realize a service choreography by reusing third-party services, hence going Troisième beyond niveau just checking its effectiveness, a further problem Quatrième worth niveau to be considered concerns: A further problem Automated choreography enforcement how to coordinate the interactions between those services discovered as suitable participants in order to fit the choreography specification 8

9 CHOReOS project 9

10 Development of choreography-based service-oriented systems (development phase roadmap) 10

11 Development of choreography-based service-oriented systems (development phase roadmap) 11

12 Development of choreography-based service-oriented systems (development phase roadmap) 12

13 Development of choreography-based service-oriented systems (development phase roadmap) 13

14 Development of choreography-based service-oriented systems (development phase roadmap) 14

15 Development of choreography-based service-oriented systems (development phase roadmap) CD1 CD2 CD4 CD5 CD2 CD3 15

16 A sample BPMN2 choreography specification Standard de facto Cliquez for specifying pour choreographies modifier les styles du texte du Dedicated notation called Choreography Diagrams 16

17 Choreography realizability enforcement problem Cliquez pour modifier les styles du texte du Given a choreography specification and a set of existing services discovered (next slide ) as suitable participants, restrict the interaction among them so to fulfill the collaboration prescribed by the Deuxième choreography niveau specification, hence preventing undesired interactions Synthesis Processor CD1 CD2 S1 S2 S3 S4 CD3 CD4 17

18 Choreography realizability enforcement problem Cliquez pour modifier les styles du texte du Given a choreography specification and a set of existing services discovered (next slide ) as suitable participants, restrict the interaction among them so to fulfill the collaboration prescribed by the Deuxième choreography niveau specification, hence preventing undesired interactions Synthesis Processor S1 CD1 S2 CD2 S1 S2 S3 S4 CD3 S3 CD4 S4 18

19 Service Discovery and Synthesis Processor Cliquez Synthesis pour modifier les styles du texte Service du Process simulates simulates Discovery expected behavior models of the roles simulates simulates Undesired interactions 19

20 CONSUMER (playing the role p1) p1:s1 Undesired interactions Undesired interactions are those interactions that do not belong to the set of interactions modeled by the given choreography and that can happen by letting the discovered services to collaborate in an uncontrolled way op1! op2! op2! 3 op1! PROVIDER (playing the role p2) op1? p2:s2 op2? op2? 3 op1? CHOREOGRAPHY BPMN2 CHOREOGRAPHY LTS p1.op1(m1).p2 p1.m4::op2(m3).p

21 CONSUMER (playing the role p1) p1:s1 Undesired interactions Undesired interactions are those interactions that do not belong to the set of interactions modeled by the given choreography and that can happen by letting the discovered services to collaborate in an uncontrolled way op1! op2! op2! 3 op1! PROVIDER (playing the role p2) op1? p2:s2 op2? op2? 3 op1? CHOREOGRAPHY BPMN2 CHOREOGRAPHY LTS p1.op1(m1).p2 p1.m4::op2(m3).p

22 CONSUMER (playing the role p1) p1:s1 Undesired interactions Undesired interactions are those interactions that do not belong to the set of interactions modeled by the given choreography and that can happen by letting the discovered services to collaborate in an uncontrolled way op1! op2! op2! 3 op1! PROVIDER (playing the role p2) op1? p2:s2 op2? op2? 3 op1? CHOREOGRAPHY BPMN2 CHOREOGRAPHY LTS p1.op1(m1).p2 p1.m4::op2(m3).p2 0 op2 1 op1 2 22

23 CONSUMER (playing the role p1) p1:s1 Undesired interactions Undesired interactions are those interactions that do not belong to the set of interactions modeled by the given choreography and that can happen by letting the discovered services to collaborate in an uncontrolled way op1! X op2! op2! 3 op1! CD1.2 PROVIDER (playing the role p2) op1? X p2:s2 op2? op2? 3 op1? CHOREOGRAPHY BPMN2 CHOREOGRAPHY LTS p1.op1(m1).p2 X p1.m4::op2(m3).p2 X 0 op2 1 op1 2 23

24 Choreography realizability enforcement via Coordination Delegates Cliquez pour modifier les styles du standard texte du S1 S2 CD1 CD3 S3 CD2 CD4 S4 communication (e.g., In only/in Out message exchange) additional communication: coordination information for coordination purposes (exchanged among the Coordination Delegates to enforce the realization of the specified choreography, in a distributed way) CHOReOS choreography realization (composition of CHOReOS connectors plus CDs) 24

25 The synthesis process at a glance Cliquez pour modifier les styles du texte du ATLAS Transformation Lang. - ATL model-to-model transformation From BPMN2 specification to CLTS specification A CLTS is an extended LTS, called Choreography LTS 25

26 BPMN2-to-CLTS transformation (1/2) 26

27 BPMN2-to-CLTS transformation (2/2) Cliquez pour modifier les styles du texte du 27

28 BPMN2-to-CLTS an example 28

29 BPMN2-to-CLTS an example 29

30 The synthesis process at a glance Cliquez pour modifier les styles du texte du ATL model-tomodel transformation From CLTS specification to Coordination Models A Coordination Model specifies coordination information 30

31 CLTS-to-Coord model transformation Cliquez pour modifier les styles du texte du S1 S2 CD1 CM1 CD2 CM2 additional communication (coordination Information) CM3 CM4 CD3 S3 CD4 S4 31

32 Coordination Model CM1.3 Coordination Models <S2,!op2, S10, CD{}, CD{1.3; 2.3}, Troisième cond1&(!cond2)&(!cond3), niveau Quatrième Notify(S9 niveau to CD(2.3)), Wait(S7 from CD(2.3))> <S10,!op2, S10, CD{}, CD{1.3, 2.3}, cond6, Notify(S9 to CD(2,3)), Wait(S7 from CD(2,3))> <S2,!op4, S20, CD{}, CD{}, cond1&(!cond2)&(!cond3)&cond4&(!cond5); Notify(), Wait()> 32

33 The synthesis process at a glance Cliquez pour modifier les styles du texte du From Coordination Models to CDs to be deployed A set of CDs artefacts is generated by means of dedicated generation rules 33

34 Overall architecture configuration Cliquez pour modifier les styles du texte du CDs run a distributed coordination algorithm for realizing choreography-coordination based on the information contained into the Coord Models 34

35 Cliquez Conclusion pour modifier les styles du texte du Automated solution to the problem of choreography realizability Deuxième enforcement niveau Conclusion and Future Work Model-based synthesis process and related model transformations Distributed algorithm for choreography-based coordination Future Directions Extension of the transformations so to transform also BPMN2 events, event-based gateways Investigation of non-functional properties of the choreography 35

36 Thank You 36