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Computational Mechanisms for Norm Enforcement in Service-Oriented Architectures

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Information about Computational Mechanisms for Norm Enforcement in Service-Oriented...
Technology

Published on March 19, 2009

Author: kemlg

Source: slideshare.net

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1 Computational mechanisms for norm enforcement in service-oriented architectures Alumne: Sergio Álvarez Napagao Profesor: Javier Vázquez Salceda Thursday, March 19, 2009

2 Contents Introduction Behaviour Monitoring in SOA Behaviour Enforcement in SOA A proposal for a Norm Enforcement Mechanism in SOA Conclusions and Working Plan Thursday, March 19, 2009

3 From the AI point of view, there is a clear opportunity: to apply concepts, algorithms, methodologies from AI research to the ser vice-orientation environments. This thesis proposal can be located in the field of computation as interaction. A paradigm that evolves Among many other challenges, we focus here on t wo of them: from monolithic computation to see computation as the need for semantic verification of the behaviour of the Introduction the result of a distributed process. SOA is the most ser vices, and the need for mechanisms that allow for a high- common reflection of the success of this paradigm: level control. For example, the most used control is based on distributed resources, accessible as services. QoS metrics, which are low level. Challenges Computation as Interaction Semantic verification of behaviour Computation as a result of the action of a network Higher-level behavioural control mechanisms Service-orientation QoS metrics -> Behavioural metrics Service-Oriented Architectures (SOA) Opportunity: apply more than 15 years of research from Resources are distributed and MAS to SOA accessed as services Thursday, March 19, 2009

4 This need for a higher-level control has not only been studied from the AI perspective, but also from the industry, using the concept of Governance. SOA Governance Governance is defined as the procedure of regulating the behaviour of the members of a society, by the use of rules promoted or motivated by the nature of this society. Corporate governance, IT governance, are examples of the application of this theoretical concept. SOA governance arised from the business industry, motivated by the need for a more fine- grained control over the process of SOA adoption. Governance conducting, influencing, regulating actions, affairs of a state, a organization, a group of people according to rules born inside this group SOA Governance: emergent concept in SOA community Business environment concerned with SOA adoption Thursday, March 19, 2009

SOA governance is, more concretely, a set of methodologies and tools that 5 supervise a SOA system, from its conception, to its design, implementation and maintenance. The motivation is that adapting monolithic applications to ser vice- orientation is too often very costly for the companies. Common problems are implementations that result to be not robust, with a low performance, and/or with compromise of security. The main problem in the end is that ser vices are not seen with confidence as a good solution. SOA governance intends to tackle SOA Governance all this. As we have seen earlier, governance is based on the application of rules. The concepts of norms and institutions could fit in here. Methodologies and tools needed to maintain order in SOA Issues to solve: Fragile and delicate SOA implementations Services that cannot easily be reused Lack of trust and confidence in services as assets Security breaches Unpredictable performance Electronic Norms and Institutions can be applied Thursday, March 19, 2009

6 A norm is a rule or standard of behaviour that applies to the members of a society. The main objective of a norm is to allow these members to be able to reason about something being acceptable or not, that is, to set a standard. Norms One of the approaches about norms found in the previous century has been Institutional Theory, leaded by North and Scott. In this approach, norms are rules that are enforced by a social institution. The purpose of having an institution setting constraints is to reduce the risk, or at least the perception of the possible risk, of human interactions. How are norms represented? A rule or standard of behaviour shared by members of a social group by which something is judged and approved or disapproved Institutional Theory approach Norms are rules supported by social institutions Institutional constraints reduce the cost of human interactions Thursday, March 19, 2009

7 Most European countries follow the model set by the Roman Law. In Roman Law, there are t wo kinds of norms: normatives, which define WHAT can be done by WHO, and the regulations: HOW a normative can be Norms applied. Laws, in the human context, are obviously represented using natural language. However, some attempts have been done to use human language in a computational context successfully. Among the logic formalisms used to represent norms, the most common is Deontic Logic, which is a modal logic based on propositional calculus which specific operators for Obligation, Permission and Prohibition. Roman Law Normatives: WHAT can be done by WHO and WHEN Regulations: HOW a normative can be applied Human language -> Logic formalization Deontic Logic (KD), based on propositional calculus O(bligation), P(ermission), F(orbidden) operators Electronic implementations tend to adapt Deontic Logic Thursday, March 19, 2009

8 As we have introduced before, an institution enforces a set of constraints in order to regulate the relationship bet ween the members of the society. Having these relationships structured Institutions and regulated allows its members to be able to act, and predict how others will act, according to some “standards”. This way, the complexity of these interactions can be higher, because the risk An institution is identified by a set of constraints governing the interactions of a society in order to structure and regulate the relationship between its members Institutions allow for a growth on the complexity of the organizations and reduce interaction costs Participants act and expect others to act according to the norms Trust among parties when having incomplete information Thursday, March 19, 2009

9 Electronic Institutions An e-institution is the model of a human institution specifying its norms in a suitable computational formalism Benefits similar to human institutions: Reduce uncertainty about other agents’ behaviour Reduce misunderstanding with a common set of norms Predictable outcome of a certain interaction Simplification of the decision-making process Literature focus is on Multi-Agent Systems Thursday, March 19, 2009

10 Objectives Incorporate an existing framework for e-Institutions in the SOA governance methodologies Adapt an e-Institutional framework to be used in SOA Two crucial elements in the generalization MAS -> SOA Capture of events: violation detection, norm enforcement Norm formalism and enforcement mechanism Contributions have been done on these fields Thursday, March 19, 2009

11 Objectives Create a mapping between To design an implement an operational representation of open-source SOA norm norms and SOA orchestration enforcement framework and choreography languages Integrate ideas and concepts Benchmark this framework common in governance and with other SOA governance institutional theories options Apply and generalize state of Adapt theories about e- the art in e-Institutions Institutions to SOA Integrate this framework in Contribute the advances done the SOA governance lifecycle to e-Institutional literature Thursday, March 19, 2009

12 Behaviour Monitoring in SOA First step in behavioural control: Monitoring Monitoring: the provision of information by the use of sensors about the system’s environment in order to take actions depending on the result of some processing Existing monitoring approaches Variable description, e.g. QoS metrics Message tracking, e.g. agent-mediated e-Institutions Problem in distributed scenarios: how to combine them? Thursday, March 19, 2009

13 Provenance Provenance is the trusted, documented history of a piece of data EU-Provenance: SOA implementation Capture of the interactions, the relationship between them, and internal states, of the members of a distributed system Based on formal semantics for unambiguous, interpretable capture Allows for monitoring of loosely-coupled distributed complex processes Thursday, March 19, 2009

14 Thursday, March 19, 2009

14 Thursday, March 19, 2009

15 Advantages of Provenance The resulting system gets the capability to produce at execution- time an explicit representation of the distributed processes taking place This representation can be queried and analyzed in order to extract valuable information to validate Documentation can be generated from both strongly or weakly connected processes Secure environment, privacy of data can be ensured Successfully applied to a distributed organ transplant management application Thursday, March 19, 2009

16 Enforcement in SOA Current approach is based on Service-Level Agreements Formal negotiated agreements between a service provider and a customer Service providers perform monitoring to verify QoS parameters Several formalisms available, but are too focused on low-level metrics and/or are too domain-specific Contracts: a more generic approach -> Behavioural Commitments Written or spoken agreements that are intended to be enforceable Containing a set of clauses that can be seen as norms Contractual e-Institutions Thursday, March 19, 2009

17 Contracting Language Our work in the EU-Contract Project: Intentional semantics in the communication between services Creation of a contracting language Creation of higher-level behavioural control mechanisms XML-based Contracting language can be used in SOA and MAS based on Deontic Logic (O, P, F) involves several layers of communication: messages and protocols Thursday, March 19, 2009

18 Contracting Language Layers Thursday, March 19, 2009

18 Contracting Language Layers Context Layer Interaction Protocol Layer Message Layer Message Content Layer Contract Layer Domain Ontology Layer Thursday, March 19, 2009

18 Contracting Language Layers Context Layer Interaction Protocol Layer Message Layer Message Content Layer Contract Layer Domain Ontology Layer Domain terms: car, workshop, repair Thursday, March 19, 2009

18 Contracting Language Layers Context Layer Interaction Protocol Layer Message Layer Message Content Layer A contract: Contract Layer “the workshop is obliged to repair the car in 2 days” Domain Ontology Layer Domain terms: car, workshop, repair Thursday, March 19, 2009

18 Contracting Language Layers Context Layer Interaction Protocol Layer Message Layer Statements / actions related to Message Content Layer contracts: cancel(contract C1) A contract: Contract Layer “the workshop is obliged to repair the car in 2 days” Domain Ontology Layer Domain terms: car, workshop, repair Thursday, March 19, 2009

18 Contracting Language Layers Context Layer Interaction Protocol Layer Message envelope + intentionality: Message Layer from service S1 to service S2 … Request[cancel(contract C1)] Statements / actions related to Message Content Layer contracts: cancel(contract C1) A contract: Contract Layer “the workshop is obliged to repair the car in 2 days” Domain Ontology Layer Domain terms: car, workshop, repair Thursday, March 19, 2009

18 Contracting Language Layers Context Layer S2 Protocol S1 Interaction Protocol Layer handling: Message envelope + intentionality: Message Layer from service S1 to service S2 … Request[cancel(contract C1)] Statements / actions related to Message Content Layer contracts: cancel(contract C1) A contract: Contract Layer “the workshop is obliged to repair the car in 2 days” Domain Ontology Layer Domain terms: car, workshop, repair Thursday, March 19, 2009

18 Contracting Language Layers uest Context Layer Req S2 Protocol S1 Interaction Protocol Layer handling: Message envelope + intentionality: Message Layer from service S1 to service S2 … Request[cancel(contract C1)] Statements / actions related to Message Content Layer contracts: cancel(contract C1) A contract: Contract Layer “the workshop is obliged to repair the car in 2 days” Domain Ontology Layer Domain terms: car, workshop, repair Thursday, March 19, 2009

18 Contracting Language Layers uest Context Layer Req S2 Protocol gree S1 Interaction Protocol Layer A handling: Message envelope + intentionality: Message Layer from service S1 to service S2 … Request[cancel(contract C1)] Statements / actions related to Message Content Layer contracts: cancel(contract C1) A contract: Contract Layer “the workshop is obliged to repair the car in 2 days” Domain Ontology Layer Domain terms: car, workshop, repair Thursday, March 19, 2009

18 Contracting Language Layers Interaction uest Context Layer Req S2 context: Protocol gree S1 Interaction Protocol Layer A handling: Message envelope + intentionality: Message Layer from service S1 to service S2 … Request[cancel(contract C1)] Statements / actions related to Message Content Layer contracts: cancel(contract C1) A contract: Contract Layer “the workshop is obliged to repair the car in 2 days” Domain Ontology Layer Domain terms: car, workshop, repair Thursday, March 19, 2009

18 Contracting Language Layers Interaction uest Context Layer Req S2 context: Protocol gree S1 Interaction Protocol Layer A handling: Message envelope + intentionality: Message Layer from service S1 to service S2 … Contractual Request[cancel(contract C1)] Ontology Statements / actions related to Message Content Layer contracts: cancel(contract C1) A contract: Contract Layer “the workshop is obliged to repair the car in 2 days” Domain Domain Ontology Layer Domain terms: car, workshop, repair Ontology Thursday, March 19, 2009

19 Language XML Structure Thursday, March 19, 2009

19 Language XML Structure Thursday, March 19, 2009

19 Language XML Structure Thursday, March 19, 2009

20 Thursday, March 19, 2009

21 Contractual Middleware A middleware has been implemented for the creation of contract- aware agent-based services, allowing to: Create contracts Handle all contract-related communication Manage the active responsibilities during contract execution Solve disputes if administrative parties are in the system Language + Middleware -> Creation of e-Institutions Thursday, March 19, 2009

22 Contract Scenario Thursday, March 19, 2009

23 Internal Architecture Thursday, March 19, 2009

24 Thesis Proposal Contractual Institution- and Provenance-based Norm Enforcement Mechanism Idea: Electronic Institutions applied to the SOA governance lifecycle Approach taken: generalization of an e-Institutional framework to SOA, and adapted to a SOA governance methodology Use of previous contributions Provenance for SOA monitoring Contracting language for norm formalism Contracting middleware for Contractual e-Institution implementation Thursday, March 19, 2009

25 Areas of work Normative framework e-Institutional framework (HARMONIA) Architecture proposal De facto standard SOA governance methodology (webMethods) Thursday, March 19, 2009

26 Normative Framework The normative framework is based on norms and landmarks HARMONIA is the basis for the normative framework Control landmarks are added (H. Aldewereld Thesis) Landmarks represent relevant (positive or negative) states of the system Actors can reason about actions to fulfill by the use of landmarks Control is not centralized, but based on the detection of violation states by the agents of the system Language for substantive norms adapted from the contracting language Thursday, March 19, 2009

27 SOA Governance Lifecycle Thursday, March 19, 2009

28 Application Agents Context Manager Agent Agent Agent assertion assertion assertion Ontology Definitions, Norm plug-in plug-in plug-in Norms, Landmarks Repository Landmark Mapping p-assertion p-assertion p-assertion Definitions, Norms, Landmarks Enforcement Engine register Provenance Monitor Store p-assertion jess rules violation Translator event Observer Agent Violation Detection jess facts Engine (JESS) Enforcement Agent Thursday, March 19, 2009

29 Application Agents Context Manager Agent Agent Agent assertion assertion assertion Ontology Definitions, Norm plug-in plug-in plug-in Norms, Landmarks Repository Landmark Mapping p-assertion p-assertion p-assertion Definitions, Norms, Landmarks Enforcement Engine register Provenance Monitor Store p-assertion jess rules violation Translator event Observer Agent Violation Detection jess facts Engine (JESS) Enforcement Agent Thursday, March 19, 2009

29 Gathers all elements needed for understandability in an institution  Vocabulary  Processes, actions  Norms  Application Agents Context Manager Agent Agent Agent assertion assertion assertion Ontology Definitions, Norm plug-in plug-in plug-in Norms, Landmarks Repository Landmark Mapping p-assertion p-assertion p-assertion Definitions, Norms, Landmarks Enforcement Engine register Provenance Monitor Store p-assertion jess rules violation Translator event Observer Agent Violation Detection jess facts Engine (JESS) Enforcement Agent Thursday, March 19, 2009

30 Application Agents Context Manager Agent Agent Agent assertion assertion assertion Ontology Definitions, Norm plug-in plug-in plug-in Norms, Landmarks Repository Landmark Mapping p-assertion p-assertion p-assertion Definitions, Norms, Landmarks Enforcement Engine register Provenance Monitor Store p-assertion jess rules violation Translator event Observer Agent Violation Detection jess facts Engine (JESS) Enforcement Agent Thursday, March 19, 2009

30 Agents that interact inside the institution and its context  Generic role with not predefined active task in norm enforcement  They should report all relevant events to the Observer Agent with p-assertions  No assumption about  Internal architecture  Reasoning cycle  Technological platform  Application Agents Context Manager Agent Agent Agent assertion assertion assertion Ontology Definitions, Norm plug-in plug-in plug-in Norms, Landmarks Repository Landmark Mapping p-assertion p-assertion p-assertion Definitions, Norms, Landmarks Enforcement Engine register Provenance Monitor Store p-assertion jess rules violation Translator event Observer Agent Violation Detection jess facts Engine (JESS) Enforcement Agent Thursday, March 19, 2009

31 Application Agents Context Manager Agent Agent Agent assertion assertion assertion Ontology Definitions, Norm plug-in plug-in plug-in Norms, Landmarks Repository Landmark Mapping p-assertion p-assertion p-assertion Definitions, Norms, Landmarks Enforcement Engine register Provenance Monitor Store p-assertion jess rules violation Translator event Observer Agent Violation Detection jess facts Engine (JESS) Enforcement Agent Thursday, March 19, 2009

31 Application Agents Context Manager Agent Agent Agent assertion assertion assertion Ontology Definitions, Norm plug-in plug-in plug-in Norms, Landmarks Repository Landmark Mapping p-assertion p-assertion p-assertion Definitions, Norms, Landmarks Enforcement Engine register Provenance Monitor Store p-assertion jess rules violation Translator event Observer Agent Violation Detection Responsible of safely register and maintain events and state changes in the institution facts jess  Engine Gathering and selection are critical processes (JESS)  Monitor  Enforcement Agent Provides a pull way of obtaining stored information  Keeps a real-time representation of the p-assertions being recorded  Enforcement Agents subscribe with a list of landmark patterns  Whenever a p-assertion is matched, it is sent to the registrant  Thursday, March 19, 2009

32 Application Agents Context Manager Agent Agent Agent assertion assertion assertion Ontology Definitions, Norm plug-in plug-in plug-in Norms, Landmarks Repository Landmark Mapping p-assertion p-assertion p-assertion Definitions, Norms, Landmarks Enforcement Engine register Provenance Monitor Store p-assertion jess rules violation Translator event Observer Agent Violation Detection jess facts Engine (JESS) Enforcement Agent Thursday, March 19, 2009

32 Application Agents Context Manager Agent Agent Agent assertion assertion assertion Ontology Definitions, Norm plug-in plug-in plug-in Norms, Landmarks Repository Landmark Mapping p-assertion p-assertion p-assertion Definitions, Norms, Landmarks Enforcement Engine register Provenance Monitor Store p-assertion jess rules violation Translator event Observer Agent Violation Detection jess facts Responsible for the fulfillment of a subset of the norms  Engine They register to the Observer Agent with a list of landmarks  (JESS) Translator  Enforcement Agent Parses p-assertions into Jess facts  Violation Detection Engine  Violations detected when executing rules (norms) with the facts  Enforcement Engine  Takes decisions and plans actions when a violation is raised  Thursday, March 19, 2009

33 Conclusions Distributed systems bring more complexity in interactions There is an opportunity to apply research of MAS in SOA From the industry there is a need for control in the SOA lifecycle We have seen 2 relevant problems Monitoring Contribution: Provenance-aware distributed complex scenario Enforcement Contribution: electronic contracting language and middleware Thursday, March 19, 2009

34 Conclusions Proposal: to join e-Institutional research and SOA governance requirements Architecture proposal High level norm-enforcement in SOA Distributed complex process and state monitoring We expect to contribute with new concepts, methods and techniques to the field of e-Institutions and to the SOA industry Thursday, March 19, 2009

35 Working Plan Jan-Apr May-Aug Sep-Dec Jan-Apr May-Aug Refinement Implementation Deployment 2009 2010 Thursday, March 19, 2009

36 Working Plan Jan-Apr May-Aug Sep-Dec Jan-Apr May-Aug Refinement Map SOA Governance and Institutional Theory common concepts. Generalization and adaptation of the contracting language to the HARMONIA framework. Implementation Integration of the contracting framework to the architecture. Identify issues and drawbacks of the architecture and solve them. Formalization of the architecture as an electronic institutional framework. Deployment 2009 2010 Thursday, March 19, 2009

37 Working Plan Jan-Apr May-Aug Sep-Dec Jan-Apr May-Aug Refinement Mapping between orchestration and choreography frameworks and operational representation of norms. Extract and define metrics, from Institutional Theory, for the evaluation of the architecture. Implementation Deployment 2009 2010 Thursday, March 19, 2009

38 Working Plan Jan-Apr May-Aug Sep-Dec Jan-Apr May-Aug Refinement Implementation Research on the suitable technologies for the implementation. Adaptation of the contracting middleware for its use in the architecture.

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