=Paper=
{{Paper
|id=None
|storemode=property
|title=Automated eContract Negotiation in Web Service Environment: Electronic Contract Management Aspects
|pdfUrl=https://ceur-ws.org/Vol-924/paper25.pdf
|volume=Vol-924
|dblpUrl=https://dblp.org/rec/conf/balt/Sauciunas12
}}
==Automated eContract Negotiation in Web Service Environment: Electronic Contract Management Aspects==
https://ceur-ws.org/Vol-924/paper25.pdf
241
Automated eContract Negotiation in Web
Service Environment: Electronic Contract
Management Aspects
Marius ŠAUČIŪNAS
Institute of Mathematics and Informatics, Vilnius University
Akademijos Str. 4, Vilnius, Lithuania
m.sauciunas@gmail.com
Abstract. The paper addresses the electronic contract management problems in
automated eContract negotiation among software agents in the web service
environment. From the point of electronic contract management, the aim of
negotiation process is to automatically form contractual agreements between
different parties, coordinating their behavior and facilitating contract execution.
The contracts specify the commitments that the involved parties make to each
other and that play the important role in their interactions. Therefore in the
contract representation language the commitments must be explicitly represented
and specify what should be done, if the legal norms defined by policies are
violated, and inform the parties about the behavior they could expect from the
others. The paper familiarizes with the details of electronic contract representation
problem and with approaches which has been proposed to solve this problem. It
presents also a critical analysis of the proposed approaches and summarizes their
challenges and drawbacks. The paper analyses also one of more advanced
conceptual framework of negotiation process from the electronic contract
representation perspective, highlights its drawbacks and proposes how to improve
this framework.
Keywords. eContract, contract representation language, deontic logic
Introduction
The subject of this paper is the critical analysis of the electronic contract management
process among the software agents in the web service environment. At present time the
whole contract lifecycle in eBusiness, including the negotiation, preparation of
eContract and its acceptation, predominantly is handled manually. In order to develop
an electronic contract, humans should not only write and agree upon it but also to
translate manually into some computer-readable internal representation [6]. The
negotiation, preparation and usage of eContracts still is a challenge.
The electronic contract representation is especially important in the dynamic
environments in which prevail the short time contracts. Such contracts have to be
dynamically set to meet end-users and service providers’ short period needs. In such
circumstances, contracts have an intrinsic dynamic and flexible nature and have to
regulate independent behavior of diverse parties. Electronic contract preparation and
execution facilitation of is one of central issues in the eContracts area.
242 M. Šaučiūnas / Automated eContract Negotiation in Web Service Environment…
The goal of the paper is to discuss state of art of the electronic contract
representation problem, to highlight the challenges and the drawbacks of the proposed
solutions, and to contrasts the conceptual modeling problems of the electronic contract
management aspects with the current negotiation process modeling concepts. The main
contribution of the paper is the proposal how to improve one of more advanced
negotiation process object-oriented modeling framework [11].
1. Electronic Contract Representation Problem
Electronic contract representation problem arises in the context of eContracting. One of
the most important requirements in the semantic Web environments that the eContracts
should prepared automatically, evaluated, negotiated and executed without human
intervention when electronic contract have an intrinsic dynamic and flexible nature and
have to regulate independent behavior of diverse parties. It seems that the
representation of electronic contracts is one of central issues in the electronic contract
monitoring and evaluation too. As pointed in [12], even the most of research in this
area focuses on this problem. The contracts specify the commitments that the involved
parties make to each other and that play the important role in their interactions. The
contract is the statement of intent that regulates the behavior of involved organizations
and individuals. Therefore in the contract representation language the commitments
must be explicitly represented and specify what should be done, if the legal norms
defined by policies are violated, and inform the parties about the behaviour they could
expect from the others. A number of such languages – LRC [3], DocLog [16],
SweetDeal [5], CEL [17], BCL [13], eContracts [10], etc. – have been proposed.
2. Electronic Contract Representation Languages
LCR (Logic for Contract Representation) is a language for description interaction in
multi-agent systems. This language based on branching-time logic, i.e. the formulae in
LCR are interpreted over tree-type branching structures that represent all conceivable
ways the system can evolve [3]. The formalism behind the language extends branching-
time temporal logic with the deontic relations. In LCR, contract clauses are represented
as deontic expressions. The violations and sanctions can also be defined in LCR.
However, the main purpose of the language is to formalize the behavior of multi-agent
system and to relate this behavior to the global objectives of the system. LCR is not
intended to be used in the web service environment.
DocLog [16] is an XML based representation language for contract terms. It is
based also on the principles of deontic and action logic. Contractual obligations are
treated as norms and represented in a semi-formal way using the extended norm frames
[9]. Although the DocLog is intended to be used in the eComerce environment and to
support the contract negotiation, the language cannot be used in sophisticated Semantic
Web environment because it cannot represent exceptions, temporal and some other
important aspects of contracts, and is semi-formal.
Quiet different approach is used in the SweetDeal [1][5] approach. It is a rule-
based approach for e-commerce business contracts representation. To describe and
communicate contracts, the SweetDeal uses a modular set of logic programming rules
about agent contracts with exception handling on top of descriptive logic based
M. Šaučiūnas / Automated eContract Negotiation in Web Service Environment… 243
ontologies, which describe business processes. Such approach enables software agents
to automate the creation, negotiation, execution, evaluation of the contracts and reuse
contract description for multiple purposes. The motivation for rule-based approach is
that rules as knowledge representation formalism is relatively mature, suitable for
prescriptive specification and already long time ago integrated into software
engineering mainstream techniques. The advantages of rules for representing
executables electronic contracts are that rules are relatively easy to modify dynamically
and that they are a high abstraction level formalism, which, at least theoretically, is
closer to humans’ understandability [14].
The start point of the SweetDeal formalism was pure logic programs. Over the
pure logic programs the so-called acyclic (non-recursive) courteous logic programs
(CLP) have been defined. CLP is a superclass of ordinary logic programs. It is
equipped with classical negation and prioritized conflict handling mechanisms [4].
Classical negation is permitted in rule heads and bodies. The courteous approach is a
hybrid approach that integrates the ideas of logic programming and general non-
monotonic reasoning. The procedural attachments can be attached to logical conditions
in the rule antecedents and consequents. CLP with procedural attachments are called
situated CLP (SCLP). SCLP expressively extends declarative ordinary logic programs
to include prioritized conflict handling. This enables modularity in specifying and
revising rule-sets. In the SweetDeal formalism the rules are represented as XML
documents [4]. Such representation enhances human readability, supports inclusion and
generation of textual information and facilitates parsing. Later this knowledge
representation formalism evolved into RuleML family [5]. RuleML was proposed as an
alternative to SWRL standard [7]. In summary, a SCLP is suitable to represent fully-
specified executable contracts as well as partially-specified contracts that are in the
midst of being negotiated [14]. The partially-specified contracts can be viewed as
contract templates [14]. The set of negotiables and the structure of a contract in terms
of services and attributes are specified by process, contract and other ontologies.
Syntactically, the names of predicates appearing in the rules may denote classes and
properties in OWL ontology and the names of individuals appearing in rules may refer
to individuals in an appropriate ontology. Semantically, the referenced ontological
knowledge base is viewed as a background theory for the rule base. Inter allies,
ontological knowledge is used for exception handling. During the execution of the
contract exception condition (e.g. late delivery, non-payment) could occur, for handling
these exceptions process knowledge is required. Thus, ontologies enable to specify
more complex contracts with behavioral provisions [5].
The SweetDeal approach is supported by an integrated set of tools, SweetRules
[15], that supports creation, evaluation, negotiation, execution and monitoring of
formal e- contracts. It provides also a communication protocol between the contracting
agents, contract knowledge bases and agent communication knowledge bases. Contract
negotiation messages exchanged between the parties are considered as contract
knowledge bases that are executable in the SweetRules environment. Each knowledge
base consists of six parts: rules, facts, ontologies, effectors, fact-queries, their answers,
and conditional queries [1]. Rules describe if-then implications of contractual
fragments. Facts are rules without bodies. Ontologies define vocabularies over which
the rules are defined. OWL ontologies and rule-based object-oriented default
inheritance ontologies are allowed. Effectors are procedural attachments of SLCP.
They can execute real-world business process (e.g. e-mail messaging) that are
244 M. Šaučiūnas / Automated eContract Negotiation in Web Service Environment…
associated with the execution of the contract. Each agent (i.e. negotiating party) has
internal knowledge base containing rules that facilitate its communication [1].
In summary, the SweetDeal approach is an well-theoretically-grounded approach
that supports many aspects of e-contracting and negotiation. However it does not
provide any means to describe deontic modalities and, consequently, is not sufficient to
define all legal aspects of negotiated contracts.
Due to volume limitations of this paper other languages will not be discussed in
detail.
3. Conceptual Modeling of Negotiation Process and Electronic Contract
Management Aspects
3.1. Analysis of the Lin’s Conceptual Framework from the Electronic Contract
Representation Perspective
The Lin’s conceptual framework [11] is one of wide-accepted conceptual models of the
negotiation process for Web services contracting. He sees this process as a
collaboration of the three conceptual entities: the service requester, the service provider
and the service discovery agency.
In the semantic Web environments the eContracts should prepared automatically,
evaluated, negotiated and executed without human intervention by software agents. In
order to negotiate about contractual agreements, the conceptual model should provide
mechanisms to specify contract structure and content, related to contract representation,
normative statements, related to involved parties behavior regulation and semantic
meaning, related to meaning of contract concepts provision. Lin’s conceptual
framework [11] does not provide any details how to do this. Most problematic issues
are the way in which the framework models the contract manager, and the proposed
protocol rules, for the signing of the contract under designated contract template. The
model assumes that the contract manager, component of service requester, is
maintaining contract template for making agreements. In eContracting environment,
where contractual agreement has an intrinsic dynamic and flexible nature, they should
be managed and negotiated by several different parties with different features and
characteristics. Contracts can never be static, rigid and agreed always under the same
contract template unless all template terms which are required for all situations will be
defined, but this will be quite difficult to manage for Semantic Web. Another way of
contract template using is to combine this solution to some other which enables to form
the architecture for automatic contract negotiation. Negotiation mechanisms which
have to be used for negotiable parameters of the contract template and to get the final
contract in not described either. Contract template structure and content not defined too.
Besides, the assumption that the service requester must maintain contract template is
questionable. These are obvious drawbacks from the contract management perspective.
Another drawback is that parties of automated contract negotiation process have no
common understanding on the concepts they agree, i.e. proposed model not deal with
semantic meaning on the party’s used terminology. Besides supporting of contracts
semantics is significant on achieving domain independency in semantic web
environments. Another drawback is that the model does not provide any business
process monitoring solution. One more assumption in the model that the agency
collects the evaluations of service providers’ presented by the requesters (trust values in
M. Šaučiūnas / Automated eContract Negotiation in Web Service Environment… 245
terms of the author) and this information should be enough to evaluate the service,
nevertheless for sophisticated evaluation according to agreed contract details this
information is insufficient.
3.2. Propositions how to Improve Lin’s Conceptual Framework
To adapt the Lin’s conceptual framework to the needs of electronic contract
management issues, it necessary, first of all, to remove the above discussed drawbacks.
Contract structure and content. The model do not provide any information
regarding contract structure and content, consequently some XML-based languages,
designed to express contractual agreements in a form, understandable for human beings,
could be used for this aim.
Figure 1. Object class diagram extension for the service requester
Involved parties’ behavior regulation and semantic meaning. One of the most
important requirements in the context of eContracting is that in semantic Web
environments the eContracts should prepared automatically, without human
intervention. Contracts should be prepared and established by software agents. Every
contract can be modeled as set of different roles, that allocates the tasks to the agents
and set of different clauses that regulates the behavior of them. Every agent, depending
on the role it is playing in electronic contract, is able or must to perform certain action.
The behavior of contractual agents needs to be regulated after contract establishment.
For this purpose contract norms, regulating the behavior, can be specified in electronic
contract. These normative statements can be modeled based on deontic logic, the logic
of the normative concepts, which represents agent’s relationship with the concepts of
obligation – agent have to do and action, permission – agent is allowed to do a action,
and prohibition – agent isn’t allowed to do an action. These concepts could be extended
by sanction concept - applied in case certain obligation hasn’t been fulfilled. In most
246 M. Šaučiūnas / Automated eContract Negotiation in Web Service Environment…
cases these concepts of deontic logic could be used to model electronic contract.
Another serious requirement for eContracts that involved parties should have common
terminology and interpretation of the contract concepts they agreed on. To achieve it,
ontology, which provides common interpretation in the domain, could be used.
Proposed model extension presents how to incorporate common and domain
ontologies. Common ontology provides meaning for general terms, needed for every
contract, while domain ontology provide domain meaning to the same terms, described
in common ontology, but make them domain independent. Common ontology, as
mentioned before, describes the general terms of the contracts e.g. deontic assignments,
modeled in deontic logic, specifies roles to perform an certain action. Activating
condition specifies conditions, which activates deontic assignment, then current state of
the statement could be tracked. Domain ontology extends common ontology terms, e.g.
Role class can be specified by three subclasses, dominating in Lin’s model, the same
rule is valid and for Action class. All these propositions modeled and provided as
extension to object class diagram (Figure 1.).
Contract monitoring. The volume of this paper does not allow me to discuss the
required solutions in detail. The main idea is that mechanisms similar to that are
provided by CONTRACT [8], TPaML [2] or ECL projects and can be used for this aim.
4. Summary and Conclusions
In this paper, the critical analysis of the electronic contract management process among
software agents in the web service environment has been performed. In such
environment, electronic contracts, with respect to intrinsic dynamic and flexible nature,
have to be prepared automatically, evaluated, negotiated and executed without human
intervention. The contract is the statement of intent that regulates the behavior of
involved organizations and individuals. From the electronic contract management
perspective, several significant aspects, such as contract structure, mechanisms to
govern collaboration between parties and contract semantic, for specifying complex
contracts with behavioral provisions, have to be taken into account dealing with the
eContract management problem. From this perspective, major groups of approaches
and mechanisms facilitating the electronic contract management problem can be
identified: an XML-based languages, languages based on branching-time, deontic,
action, programming rules logic, policy-based approaches, role-based approaches. The
drawbacks and challenges of each group have been discussed in the paper. Further, the
object-oriented Lin’s negotiation model [11] that is accepted by many researchers
working in the automated negotiation field has been evaluated from the electronic
contract management perspective. Its shortcomings have been highlighted, and some
significant improvements of the model have been proposed.
The critical analysis of the automated eContract management problem
demonstrates, that a lot of different approaches and useful ideas have been proposed up
to date, some of them could be distinguished for further investigation and model
improvement, e.g. XML-based languages, designed to express contractual agreements
in a form, understandable for human beings, role based architectures, contract
templates, ontologies, another solutions, not mentioned in this paper due to volume
limitation, but which are important to monitoring and evaluation areas. A lot of
experimental research should be done for this aim. It intends to be a major focus of my
further research.
M. Šaučiūnas / Automated eContract Negotiation in Web Service Environment… 247
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