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Computational Mechanisms for Norm Enforcement in Service-Oriented Architectures
1. 1
Computational mechanisms
for norm enforcement in
service-oriented architectures
Alumne: Sergio Álvarez Napagao
Profesor: Javier Vázquez Salceda
Thursday, March 19, 2009
2. 2
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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3. 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
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4. 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
5. 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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6. 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
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7. 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
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8. 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
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9. 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
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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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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
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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
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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
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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
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26. 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
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27. 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
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28. 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
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29. 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
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Language XML Structure
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Language XML Structure
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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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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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47. 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
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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
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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52. 35
Working Plan
Jan-Apr May-Aug Sep-Dec Jan-Apr May-Aug
Refinement
Implementation
Deployment
2009 2010
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53. 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
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54. 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
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55. 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.
Deployment
2009 2010
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56. 39
Working Plan
Jan-Apr May-Aug Sep-Dec Jan-Apr May-Aug
Refinement
Implementation
Implementation of the components of the architecture.
Integration of the use case in the implementation.
Deployment
2009 2010
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57. 40
Working Plan
Jan-Apr May-Aug Sep-Dec Jan-Apr May-Aug
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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58. 41
Working Plan
Jan-Apr May-Aug Sep-Dec Jan-Apr May-Aug
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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Thanks for your attention
Questions?
Thursday, March 19, 2009
Notas del editor
Studied by institutionalists such as North & Scott
When working with norms in computational environments, there are several issues that arise. For instance, there are several kinds of norms. For example, in Roman Law, there are two ... blah
A second issue is that in computational environments one cannot use human language, ...
This idea has been brought to the computer science in the form of electronic institutions.
ENTRENAR crucial elements
ENTRENAR
NO REPETIR LOS DOS POINTS
Our previous research on the topic (monitoring) has been based on the concept of Provenance.
ENTRENAR: Based on formal semantics for unambiguous, interpretable capture (pi-calculus)
ENTRENAR
We can see which is the basis for a given action or decision.
Provenance questions: WHY, WHO, WHEN, WHAT + deviations can be detected at a glance
Ejemplos QoS: response time? uptime? Buscar ejemplos.
ENTRENAR parte de Contracts
- Clausulas vistas como normas
- Ejecucion de contrato visto como institucion
ENTRENAR
Interaction Context reflects the operational consequences of the interactions held by the parties. Ejemplo: efecto de cancelar C1 cuando alguien debe algo.
ENTRENAR
Interaction Context reflects the operational consequences of the interactions held by the parties. Ejemplo: efecto de cancelar C1 cuando alguien debe algo.
ENTRENAR
Interaction Context reflects the operational consequences of the interactions held by the parties. Ejemplo: efecto de cancelar C1 cuando alguien debe algo.
ENTRENAR
Interaction Context reflects the operational consequences of the interactions held by the parties. Ejemplo: efecto de cancelar C1 cuando alguien debe algo.
ENTRENAR
Interaction Context reflects the operational consequences of the interactions held by the parties. Ejemplo: efecto de cancelar C1 cuando alguien debe algo.
ENTRENAR
Interaction Context reflects the operational consequences of the interactions held by the parties. Ejemplo: efecto de cancelar C1 cuando alguien debe algo.
ENTRENAR
Interaction Context reflects the operational consequences of the interactions held by the parties. Ejemplo: efecto de cancelar C1 cuando alguien debe algo.
ENTRENAR
Interaction Context reflects the operational consequences of the interactions held by the parties. Ejemplo: efecto de cancelar C1 cuando alguien debe algo.
ENTRENAR
Interaction Context reflects the operational consequences of the interactions held by the parties. Ejemplo: efecto de cancelar C1 cuando alguien debe algo.
ENTRENAR
Interaction Context reflects the operational consequences of the interactions held by the parties. Ejemplo: efecto de cancelar C1 cuando alguien debe algo.
ENTRENAR
Interaction Context reflects the operational consequences of the interactions held by the parties. Ejemplo: efecto de cancelar C1 cuando alguien debe algo.
ENTRENAR
Interaction Context reflects the operational consequences of the interactions held by the parties. Ejemplo: efecto de cancelar C1 cuando alguien debe algo.
ENTRENAR
Interaction Context reflects the operational consequences of the interactions held by the parties. Ejemplo: efecto de cancelar C1 cuando alguien debe algo.
ENTRENAR
Interaction Context reflects the operational consequences of the interactions held by the parties. Ejemplo: efecto de cancelar C1 cuando alguien debe algo.
ENTRENAR
Interaction Context reflects the operational consequences of the interactions held by the parties. Ejemplo: efecto de cancelar C1 cuando alguien debe algo.
ENTRENAR
Interaction Context reflects the operational consequences of the interactions held by the parties. Ejemplo: efecto de cancelar C1 cuando alguien debe algo.
ENTRENAR
Our main idea is that, by combining a language and a middleware for contracting, we can create a special kind of electronic institutions.
ENTRENAR: empezar con Contract Parties -> 3rd party -> Notary -> Conflict Manager
Los ovalos son Contract-Aware Services. (ENLACE)
This is the Internal Architecture of a Contract-Aware service
Landmarks -> ENTRENAR
We will actually use the extension made by Huib which are control landmarks.
Landmarks son critical states: norm enforcement based on critical states!
This is possible because there is a mapping done between deontic logics and LTL.
HARMONIA covers several layers of normative abstraction from low to high level.
Taking into account this SOA governance framework and our previous research on normative systems, we present this architecture proposal.
Proof-of-concept. Some of the components have been already prototyped.
NO CONTRACTS!
Norms and agents entering an institution!