Computational Mechanisms for Norm Enforcement in Service-Oriented Architectures

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Computational mechanisms
for norm enforcement in
service-oriented architectures
Alumne: Sergio Álvarez Napagao

Profesor: Javier Vázquez Salceda

Thursday, March 19, 2009

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Contents

Introduction

Behaviour Monitoring in SOA

Behaviour Enforcement in SOA

A proposal for a Norm Enforcement Mechanism in SOA

Conclusions and Working Plan


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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


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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


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


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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


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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


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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


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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


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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


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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


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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?


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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


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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


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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


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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


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Contracting Language Layers


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Context Layer

Interaction Protocol Layer

Message Layer

Message Content Layer

Contract Layer

Domain Ontology Layer


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Context Layer


Message Layer


Contract Layer

Domain Ontology Layer Domain terms: car, workshop, repair


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Context Layer


Message Layer


A contract:
Contract Layer “the workshop is obliged to
repair the car in 2 days”



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Context Layer


Message Layer

Statements / actions related to
Message Content Layer contracts:
cancel(contract C1)
A contract:



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Context Layer


Message envelope + intentionality:
Message Layer from service S1 to service S2 …
Request[cancel(contract C1)]
cancel(contract C1)
A contract:



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Context Layer S2

Protocol
S1
Interaction Protocol Layer handling:

cancel(contract C1)
A contract:



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uest
Context Layer Req S2

Protocol
S1
Interaction Protocol Layer handling:

cancel(contract C1)
A contract:



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uest

Protocol
gree
S1
Interaction Protocol Layer A
handling:

cancel(contract C1)
A contract:



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Interaction
uest
context:

Protocol
gree
S1
handling:

cancel(contract C1)
A contract:



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Interaction
uest
context:

Protocol
gree
S1
handling:

Contractual
Ontology
cancel(contract C1)
A contract:
Domain
Ontology


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Language XML Structure


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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


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Contract Scenario


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Internal Architecture


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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


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Areas of work

Normative framework

e-Institutional framework (HARMONIA)

Architecture proposal

De facto standard SOA governance methodology (webMethods)


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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


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SOA Governance Lifecycle


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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


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Application Agents

Context Manager
Agent Agent Agent

Deﬁnitions, Norm

Landmark
Mapping

p-assertion
Deﬁnitions,
Norms, Landmarks

Enforcement
Engine
register
Provenance Monitor
Store
violation
Translator
event
Observer Agent
Violation
Detection
jess facts
Engine
(JESS)

Enforcement Agent


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Gathers all elements needed for understandability in an institution


Vocabulary


Processes, actions


Norms


Application Agents

Context Manager
Agent Agent Agent

Deﬁnitions, Norm

Landmark
Mapping

p-assertion
Deﬁnitions,
Norms, Landmarks

Enforcement
Engine
register
Provenance Monitor
Store
violation
Translator
event
Observer Agent
Violation
Detection
jess facts
Engine
(JESS)

Enforcement Agent


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Application Agents

Context Manager
Agent Agent Agent

Deﬁnitions, Norm

Landmark
Mapping

p-assertion
Deﬁnitions,
Norms, Landmarks

Enforcement
Engine
register
Provenance Monitor
Store
violation
Translator
event
Observer Agent
Violation
Detection
jess facts
Engine
(JESS)

Enforcement Agent


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

Definitions, Norm

Landmark
Mapping

p-assertion
Definitions,
Norms, Landmarks

Enforcement
Engine
register
Provenance Monitor
Store
violation
Translator
event
Observer Agent
Violation
Detection
jess facts
Engine
(JESS)

Enforcement Agent


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Application Agents

Context Manager
Agent Agent Agent

Deﬁnitions, Norm

Landmark
Mapping

p-assertion
Deﬁnitions,
Norms, Landmarks

Enforcement
Engine
register
Provenance Monitor
Store
violation
Translator
event
Observer Agent
Violation
Detection
jess facts
Engine
(JESS)

Enforcement Agent


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Application Agents

Context Manager
Agent Agent Agent

Deﬁnitions, Norm

Landmark
Mapping

p-assertion
Deﬁnitions,
Norms, Landmarks

Enforcement
Engine
register
Provenance Monitor
Store
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



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Application Agents

Context Manager
Agent Agent Agent

Deﬁnitions, Norm

Landmark
Mapping

p-assertion
Deﬁnitions,
Norms, Landmarks

Enforcement
Engine
register
Provenance Monitor
Store
violation
Translator
event
Observer Agent
Violation
Detection
jess facts
Engine
(JESS)

Enforcement Agent


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Application Agents

Context Manager
Agent Agent Agent

Definitions, Norm

Landmark
Mapping

p-assertion
Definitions,
Norms, Landmarks

Enforcement
Engine
register
Provenance Monitor
Store
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



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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


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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


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Working Plan
Jan-Apr May-Aug Sep-Dec Jan-Apr May-Aug

Reﬁnement

Implementation

Deployment

2009 2010

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Working Plan

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

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Working Plan

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

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Working Plan

Reﬁnement

Implementation

Research on the suitable technologies for the implementation.
Adaptation of the contracting middleware for its use in the architecture.

Deployment

2009 2010

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Working Plan

Reﬁnement

Implementation

Implementation of the components of the architecture.
Integration of the use case in the implementation.

Deployment

2009 2010

40

Working Plan

Reﬁnement

Design of the test cases.
Creation of testbeds for the deployment.
Implementation
Deployment of the use case in the testbeds.
Benchmark of the results of the testbed executions.

Deployment

2009 2010

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Working Plan

Reﬁnement

Implementation
Integration of the architecture in a SOA governance methodology lifecycle.
Benchmark of the results of the architecture.
Find issues concerning the performance of the architecture.

Deployment

2009 2010

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Publications
Sergio Alvarez-Napagao and Javier Vázquez-Salceda, Using Provenance to implement a Norm Enforcement Mechanism for
Agent-Mediated Healthcare Systems, Proceedings of the Fifth Workshop on Agents Applied in Health Care at AAMAS’08, Estoril,
Portugal (2008), 8.
Sergio Alvarez-Napagao, Javier Vázquez-Salceda, Tamás Kifor, László Z Varga, and Steven Willmott, Applying provenance
in distributed organ transplant management, International Provenance and Annotation workshop (IPAW 2006), 3-5 May 2006,
Chicago, USA, ISBN 978-3-540-46302-3 (2006).
Roberto Confalonieri, Sergio Alvarez-Napagao, Soﬁa Panagiotidi, Javier Vázquez-Salceda, and Steven Willmott, A
Middleware Architecture for Building Contract-Aware Agent-Based Services, Proceedings of the International Workshop on
Service-Oriented Computing: Agents, Semantics, and Engineering -SOCASE’08-, at AAMAS’08, Estoril, Portugal, ISBN
978-3-540-79967-2 (2008).
Tamás Kifor, László Z Varga, Sergio Alvarez-Napagao, Javier Vázquez-Salceda, and Steven Willmott, Privacy Issues of
Provenance in Electronic Healthcare Record Systems, First International Workshop on Privacy and Security in Agent-based
Collaborative Environments (PSACE2006), Hakodata, Japan (2006).
Tamás Kifor, László Z Varga, Javier Vázquez-Salceda, Sergio Alvarez-Napagao, Steven Willmott, Simon Miles, and Luc
Moreau, Provenance in Agent-mediated Healthcare Systems, IEEE Intelligent Systems, ISSN 1541-1672-21 (2006), no. 6, 38–46.
Soﬁa Panagiotidi, Javier Vázquez-Salceda, Sergio Alvarez-Napagao, Steven Willmott, and Roberto Confalonieri, Intelligent
Contracting Agents Language, Proceedings of the Symposium on Behaviour Regulation in Multi-Agent Systems -BRMAS’08-,
Aberdeen, UK (2008).
Javier Vázquez-Salceda and Sergio Alvarez-Napagao, Using SOA Provenance to Implement Norm Enforcement in e-
Institutions, Proceedings of the Workshop on Coordination, Organizations, Institutions and Norms - COIN@AAAI08-, at AAAI 08,
Chicago, USA (2008).
Javier Vázquez-Salceda, Sergio Alvarez-Napagao, Tamás Kifor, László Z Varga, Simon Miles, Luc Moreau, and Steven
Willmott, EU PROVENANCE Project: An Open Provenance Architecture for Distributed Applications, R. Annicchiarico, U. Cortés,
C. Urdiales (eds.) Agent Technology and E-Health. Whitestein Series in Software Agent Technologies and Autonomic Computing.
Birkhäuser Verlag AG, Switzerland, ISBN: 978-3-7643-8546-0 (2007), 55–64.


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