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Dynamic Matching of Services by Negotation
Abstract
This paper presents my research project on the topic of dynamic matching of services by negotiation. The goal of the research is to develop a design theory for information systems that offer negotiation services. The result of the research will be a specification of a design framework for such systems. This framework will contain knowledge about architectural choices one has to make when designing an information system with particular properties satisfying particular requirements.
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Requirements Engineering for business solutions have so far primarily dealt with the elicitation, specification, validation, management and change to information systems to be accessed through PCs and workstations. As mobile solutions are applied in more and more situations, additional challenges will meet those that specify the requirements to the applications running on mobile technology. This position paper summarises some of these challenges, and points to areas for research that should receive the attention of the RE community.
In this paper, we argue that middleware for wired distributed systems cannot be used in a mobile setting, as the principle of trans- parency that has driven their design runs counter to the new degrees of awareness imposed by mobility. We propose the marriage of reection and metadata as a means for middleware to give applications dynamic access to information about their execution context. Finally, we describe a conceptual model that provides the basis of our reective middleware.
The emerging paradigm of electronic services promises to bring to distributed computation and services the flexibility that the web has brought to the sharing of documents. An understanding of fundamental properties of e-service composition is required in order to take full advantage of the paradigm. This paper examines proposals and standards for e-services from the perspectives of XML, data management, workflow, and process models. Key areas for study are identified, including behavioral service signatures, verification and synthesis techniques for composite services, analysis of service data manipulation commands, and XML analysis applied to service specifications. We give a sample of the relevant results and techniques in each of these areas.
Towards the ultimate goal of seamless interaction among networked programs and devices, industry has developed orchestration and process model- ing languages such as XLANG, WSFL, and recently BPEL4WS. Unfortunately, these efforts leave us a long way from seamless int eroperation. Researchers in the Semantic Web community have taken up this challenge proposing top-down approaches to achieve aspects of Web Service intero peration. Unfortunately, many of these efforts have been disconnected from e merging industry stan- dards, particularly in process modeling. In this pa per we take a bottom-up ap- proach to integrating Semantic Web technology into Web services. Building on BPEL4WS, we present integrated Semantic Web technology for automating customized, dynamic binding of Web services together with interoperation through semantic translation. We discuss the value of semantically enriched service interoperation and demonstrate how our framework accounts for user- defined constraints while gaining potentially succe ssful execution pathways in a practically motivated example. Finally, we provide an analysis of the forward- looking limitations of frameworks like BPEL4WS, and suggest how such speci- fications might embrace semantic technology at a fu ndamental level to work towards fully automated Web service interoperation.
One of the most challenging problems that web-service enabled e-marketplaces face is the lack of support for appropriate service
request languages that retrieve and aggregate services relevant to a business problem. We present an architectural framework
for web-service interaction based on planning and constraint satisfaction, and a webservice request language (WSRL) developed
on the basis of this framework. This framework is capable of performing planning under uncertainty on the basis of refinement
and revision as new service-related information is accumulated (via interaction withth e user or UDDI) and as execution circumstances
necessitate change.
The Web has becomes the means for enterprises to deliver
electronic services to businesses and customers, and for service
providers to discover services and build complex applications by using
existing services. The number of e-services is growing rapidly,. This
has raised the opportunity for e-service oriented marketplaces to
provide the facilities for developing value-added services by combining
existing e-services. We explore the characteristics of service
composition, show how it differs in fundamental ways from traditional
issues surrounding workflow integration, data integration, and
application integration. We provide a framework for classifying
different scenarios of service composition, discuss the unique
requirements of service composition, and outline our solution for the
challenging issues in service composition
Nowadays the anytime/anywhere/anyone paradigm is be- coming very important and new applications are being developed in many contexts. The possibility of using applications along a wide range of devices, networks, and protocols raises new problems related to deliv- ery of services. Current academic and industrial solutions try to adapt services to the specific distribution channel, mainly by changing the pre- sentation of the service. In this paper, we reverse this perspective by using adaptive strategies to try to adapt the delivery channel to services as well. We present a possible architecture and focus our attention on the use of reflective components in the adaptive process. Using the re- flection principle, we are able to evaluate the channel constraints and the conditions in which the distribution channel is working at a specific time. This information, built with service, user, and context constraints, is used as input to adaptive strategies to change the current channel characteristics, to new ones satisfying all the requirements. If this kind of adaptation is not possible, we consider the different QoS levels offered by the service and the user's readiness to accept a downgraded service provisioning.
The main focus of this paper is on automatic e-Service com- position. We start by developing a framework in which the exported behavior of an e-Service is described in terms of its possible executions (execution trees). Then we specialize the framework to the case in which such exported behavior (i.e., the execution tree of the e-Service) is rep- resented by a finite state machine. In this specific setting, we analyze the complexity of synthesizing a composition, and develop sound and com- plete algorithms to check the existence of a composition and to return one such a composition if one exists. To the best of our knowledge, our work is the first attempt to provide an algorithm for the automatic syn- thesis of e-Service composition, that is both proved to be correct, and has an associated computational complexity characterization.
Composition of e-Services is the issue of synthesizing a new composite e- Service, obtained by combining a set of available component e-Services, when a client request cannot be satised by available e-Services. In this paper we propose a general framework addressing the problem of e-Service composition. We then show that, under certain assumptions, composition can be realized through DL- based reasoning.
A virtual district is defined as a consortium of independent member enterprises which operate in an integrated and organic
way to exploit business opportunities. Such enterprises cooperate to achieve common goals following agreed upon cooperative processes.
Considering a cooperative process as a set of activities performed by e-Services provided by the different enterprises, this work studies the compatibility among e-Services to support the dynamic substitution of failed or modified e-Services.
The methodology takes into account both syntactic and semantic analysis, using a domain ontology to match the different terminology
used by the different e-Service providers.
Web services are emerging as a promising technology for the eectiv e automation of inter-organizational interactions. Several stan- dards that aim at providing infrastructure to support Web services de- scription, discovery, and composition have recently emerged including WSDL, UDDI, and BPEL4WS. Indeed, advances in this area promise to take cross-organizational application integration a step further by fa- cilitating the automatic discovery and invocation of relevant services. However, despite the growing interest in Web services, several issues still need to be addressed to provide similar benets to what traditional middleware brings to intra-organizational application integration (e.g., transaction support). In this paper, we identify a framework for dening extended service models to enable the denition of richer Web service abstractions. We also identify and dene specic abstractions based on an analysis of existing e-commerce Web portals. Finally, we show how the model and the abstractions are supported by a conversation manager implemented on top of the SELF-SERV platform.
The design and the development of multichannel information systems require new approaches, mainly based on the definition of adaptive behavior with the goal of increasing the efficiency and effectiveness of solutions. In this paper, we show a simplified example of financial information system, where several ser- vices impose constraints. The approach we propose tries to solve these service limitations by means of an enriched definition of channel and new logical primi- tives. These are then used to define rating classes that will be the starting point of our adaptive strategies.
This paper presents an approach to temporal reasoning in which prediction is deduction but explanation is abduction. It is argued that all causal laws should be expressed in the natural form effect if cause. Any given set of laws expressed in this way can be used for both forwards projection (prediction) and backwards projection (explanation), but abduction must be used for explanation whilst deduction is used for prediction. The approach described uses a shortened form of Kowalski and Sergot's Event Calculus and incorporates the assumption that properties known to hold must have explanations in terms of events. Using abduction to implement this assumption results in a form of default persistence which correctly handles problems which have troubled other formulations. A straightforwar d extension to SLD resolution is described which implements the abductive approach to explanation, and which complements the well-understood deductive methods for prediction.
Business and military partners, companies and their customers, and other closely cooperating parties may have a compelling need to conduct sensitive interactions on line, such as accessing each other's local services and other local resources. Automated trust negotiation is an approach to establishing trust between parties so that such interactions can take place, through the use of access control policies that specify what combinations of digital credentials a stranger must disclose to gain access to a local resource. A party can use many different strategies to negotiate trust, offering tradeoffs between the length of the negotiation, the amount of extraneous information disclosed, and the computational effort expended. To preserve parties' autonomy, each party should ideally be able to choose its negotiation strategy independently, while still being guaranteed that negotiations will succeed whenever possible---that the two parties' strategies will interoperate. In this paper we provide the formal underpinnings for that goal, by formalizing the concepts of negotiation protocols, strategies, and interoperation. We show how to model the information flow of a negotiation for use in analyzing strategy interoperation. We also present two large sets of strategies whose members all interoperate with one another, and show that these sets contain many practical strategies. We develop the theory for black-box propositional credentials as well as credentials with internal structure, and for access control policies whose contents are (respectively are not) sensitive. We also discuss how these results fit into TrustBuilder, our prototype system for trust negotiation.
We describe a novel framework for specifying and monitoring Service Level Agreements (SLA) for Web Services. SLA monitoring and enforcement become increasingly important in a Web Service environment where enterprise applications and services rely on services that may be subscribed dynamically and on-demand. For economic and practical reasons, we want an automated provisioning process for both the service itself as well as the SLA managment system that measures and monitors the QoS parameters, checks the agreed-upon service levels, and reports violations to the authorized parties involved in the SLA management process. Our approach to these issues is presented in this paper. The Web Service Level Agreement (WSLA) framework is targeted at defining and monitoring SLAs for Web Services. Although WSLA has been designed for a Web Services environment, it is applicable as well to any inter-domain management scenario, such as business process and service management, or the management of networks, systems and applications in general. The WSLA framework consists of a flexible and extensible language based on XML Schema and a runtime architecture comprising several SLA monitoring services, which may be outsourced to third parties to ensure a maximum of objectivity. WSLA enables service customers and providers to unambiguously define a wide variety of SLAs, specify the SLA parameters and the way they are measured, and relate them to managed resource instrumentations. Upon receipt of an SLA specification, the WSLA monitoring services are automatically configured to enforce the SLA. An implementation of the WSLA framework, termed SLA Compliance Monitor, is publicly available as part of the IBM Web Services Toolkit.
By reducing the costs of coordination, information technology will lead to an overall shift toward proportionately more use of markets—rather than hierarchies—to coordinate economic activity.
Advances in wireless technology increase the number of mobile device users and give pace to the rapid development of e-commerce using these devices. The new type of e-commerce, conducting transactions via mobile terminals, is called mobile commerce. Due to its inherent characteristics such as ubiquity, personalization, flexibility, and dissemination, mobile commerce promises businesses unprecedented market potential, great productivity, and high profitability. This paper presents an overview of mobile commerce development by examining the enabling technologies, the impact of mobile commerce on the business world, and the implications to mobile commerce providers. The paper also provides an agenda for future research in the area.
A significant number of companies are re-engineering their business to be more effective and productive. Consequently, existing applications must be modified, and new applications must be written. The new applications typically run in a distributed and heterogeneous environment, performing single tasks in parallel, and demanding special transaction functionality for the supporting environments. Workflow-based applications offer this type of capability. In this paper, their principal advantages are derived and set in context to transaction, object, and CASE (computer-assisted software engineering) technology. In particular, a method is proposed to develop these workflow-based applications in a cohesive and consistent way.
In this paper we present DAML-S, a DAML+OIL ontology for describing
the properties and capabilities of Web Services. Web Services --
Web-accessible programs and devices -- are garnering a great deal of
interest from industry, and standards are emerging for low-level
descriptions of Web Services. DAML-S complements this effort by
providing Web Service descriptions at the application layer,
describing what a service can do, and not just how it
does it. In this paper we describe three aspects of our ontology: the
service profile, the process model, and the service grounding. The
paper focuses on the grounding, which connects our ontology with
low-level XML-based descriptions of Web Services.
The process-driven composition of Web services is emerging as a promising approach to integrate business applications within and across organizational boundaries. In this approach, individual Web services are federated into composite Web services whose business logic is expressed as a process model. The tasks of this process model are essentially invocations to functionalities offered by the underlying component services. Usually, several component services are able to execute a given task, although with different levels of pricing and quality. In this paper, we advocate that the selection of component services should be carried out during the execution of a composite service, rather than at design-time. In addition, this selection should consider multiple criteria (e.g., price, duration, reliability), and it should take into account global constraints and preferences set by the user (e.g., budget constraints). Accordingly, the paper proposes a global planning approach to optimally select component services during the execution of a composite service. Service selection is formulated as an optimization problem which can be solved using efficient linear programming methods. Experimental results show that this global planning approach outperforms approaches in which the component services are selected individually for each task in a composite service.
This article reports on the growth of the Internet networking systems and its positive effects in increasing businesses participating in e-commerce. One of the key characteristics of the e-business world is that companies will inevitably move more and more into a customer-centric paradigm in order to increase competitiveness. Customer behavior cannot be accurately predicted using traditional analytic methods like forecasting or budgeting. Instead, companies seeking a competitive edge will investigate other kinds of analytical methods based on, for example, heuristics. Intelligent business agents are the next higher level of abstraction in model-based solutions to business-to-business e-commerce applications. By building on the distributed object foundation, agent technology can help bridge the remaining gap between flexible design and usable applications. This technology allows the development of rich and expressive models of an enterprise and lays the foundation for adaptive, reusable business software. Agent-oriented technology can be leveraged to enhance enterprise modeling as well as to offer new techniques for developing intelligent applications and infrastructure services.
Decoupling authorization logic from application logic allows
applications with fine-grain access control requirements to be
independent of a particular access control policy and from factors that
are used in authorization decisions as well as access control models, no
matter how dynamic those policies and factors are. It also enables
elaborate and consistent access control policies across heterogeneous
systems. We present the design of a service for resource access
authorization in distributed systems. The service enables one to
decouple authorization logic from application functionality. Although
the described service is based on CORBA technology, the design approach
can be successfully used in any distributed computing environment
The authors describe a system whose purpose is to explore the use
of certificates for the distributed management of access rights for
resources that have multiple, independent, and geographically dispersed
stakeholders. The stakeholders assert their use-conditions in
authorization certificates and designate those trusted to attest to the
corresponding attributes. These use-conditions implicitly define access
groups through their requirement for certain attributes. All
use-conditions must be satisfied simultaneously, so the actual access
group is the intersection of all of the groups. A policy engine collects
the use-condition certificates and attribute certificates when a user
attempts to access a particular resource. If all of the use-conditions
are met, a capability is generated for the resource. The policy engine
can provide several different policy models depending on whether any
relationship is established among the use-conditions. The system
architecture and implementation is described, together with some of the
identified strengths, weaknesses, and vulnerabilities
Service-driven architectures promise a new paradigm providing an extremely flexible approach for building complex information systems. However, at the current moment, service architectures go little way beyond standardized remote procedure calls and textual directories to locate and describe a service provider based on human intervention. In this paper we consider three important dimensions for building next-generation service-driven systems building on enabling technologies such as Web services, Peer-2-Peer and Semantic Web.
In this paper we propose a foundational vision of e-Services, in which we distinguish between the external behavior of an e-Service as seen by clients, and the internal behavior as seen by a deployed application running the e-Service. Such behaviors are formally expressed as execution trees describing the interactions of the e-Service with its client and with other e-Services. Using these notions we formally define e-Service composition in a general way, without relying on any specific representation formalism. We have also provide a classification of e-Services based on relevant properties of the execution trees.
This document defines a notation for specifying business process behavior based on Web Services. This notation is called Business Process Execution Language for Web Services (abbreviated to BPEL4WS in the rest of this document). Processes in BPEL4WS export and import functionality by using Web Service interfaces exclusively. Business processes can be described in two ways. Executable business processes model actual behavior of a participant in a business interaction. Business protocols, in contrast, use process descriptions that specify the mutually visible message exchange behavior of each of the parties involved in the protocol, without revealing their internal behavior. The process descriptions for business protocols are called abstract processes. BPEL4WS is meant to be used to model the behavior of both executable and abstract processes. BPEL4WS provides a language for the formal specification of business processes and business interaction protocols. By doing so, it extends the Web Services interaction model and enables it to support business transactions. BPEL4WS defines an interoperable integration model that should facilitate the expansion of automated process integration in both the intra-corporate and the business-to-business spaces. 3 Status This is a second public draft release of the BPEL4WS specification. BPEL4WS represents a convergence of the ideas in the XLANG and WSFL specifications. Both XLANG and WSFL are superseded by the BPEL4WS specification. 4 Contents 1
With the increasing growth in popularity of Web services, discovery of relevant Web services becomes a significant challenge. One approach is to develop semantic Web services where by the Web services are annotated based on shared ontologies, and use these annotations for semantics-based discovery of relevant Web services. We discuss one such approach that involves adding semantics to WSDL using DAML+OIL ontologies. Our approach also uses UDDI to store these semantic annotations and search for Web services based on them. We compare our approach with another initiative to add semantics to support Web service discovery, and show how our approach may fit current standards-based industry approach better.
The real value of Semantic Web vision can be demonstrated if people and applications can create and discover new and interesting knowledge and share this knowledge in a transparent manner similar to the way data is exchanged today. Therefore, we believe that Semantic Web will consist of a distributed environment of shared and interoperable ontologies, which have emerged as common formalisms for knowledge representation. The users will need to discover new ontologies, which are not known to them before and use them to either annotate the content or to formulate their information requests. This requires an environment that supports creating, maintaining, and controlled sharing of ontologies. We believe that a Peer-to-Peer (P2P) infrastructure can enable such capabilities. We call our approach P2P Semantic Web (PSW) with capabilities to find relevant set of ontologies, facilitating reuse of existing ontologies to create additional ontologies, and advertising the resulting ontologies. We discuss an ontology driven search of concepts and services and exploration of inter-ontological relationships over a P2P infrastructure. The prototyping of this approach in the InfoQuilt system is also discussed.
The web is moving from being a collection of pages toward a collection of services that interoperate through the Internet. A fundamental step toward this interoperation is the ability of automatically locating services on the bases of the functionalities that they provide. Such a functionality would allow services to locate each other and automatically interoperate. Location of web services is inherently a semantic problem, because it has to abstract from the superficial differences between representations of the services provided, and the services requested to recognize semantic similarities between the two. Current Web Services technology based on UDDI and WSDL does not make any use of semantic information and therefore fails to address the problem of matching between capabilities of services and allowing service location on the bases of what functionalities are sought, failing therefore to address the problem of locating web services. Nevertheless, previous work within DAML-S, a DAML-based language for service description, shows how ontological information collected through the semantic web can be used to match service capabilities. This work expands on previous work by showing how DAML-S Service Profiles, that describe service capabilities within DAML-S, can be mapped into UDDI records providing therefore a way to record semantic information within UDDI records. Furthermore we show how this encoded information can be used within the UDDI registry to perform semantic matching.
Database Support for Workflow Management: The WIDE Project presents the results of the ESPRIT WIDE project on advanced database support for workflow management. The book discusses the state of the art in combining database management and workflow management technology, especially in the areas of transaction and exception management. This technology is complemented by a high-level conceptual workflow model and associated workflow application design methodology. In WIDE, advanced base technology is applied, like a distributed computing model based on the corba standard. The usability of the WIDE approach is documented in this book by a discussion of two real-world applications from the insurance and health care domains.
Database Support for Workflow Management: The WIDE Project serves as an excellent reference, and may be used for advanced courses on database and workflow management systems.
The advent of nearly ubiquitous information infrastructures has led many to predict that one effect of electronic markets will be the bypassing of intermediaries in electronic markets. The ability of electronic networks to reduce transaction costs is the theoretical cause of this supposed trend. We suggest that, on the contrary, not only is it likely that widely available information infrastructures will reinforce the position of traditional intermediaries, but that networks will also promote the growth of a new generation of intermediaries. These new players, which we term “Cybermediaries,” are organizations that perform the mediating tasks in the world of electronic commerce. We illustrate that the case for the elimination of intermediaries in the move to create direct producer-consumer links is based on questionable assumptions. We then examine functions of intermediaries that are not easily absorbed by producers. We describe some of the new forms of cybermediaries, noting the new needs that electronic commerce imposes on producers and consumers. We note that using a rational, economic logic rooted in transaction cost theory, it is equally plausible to conclude that more, rather than fewer intermediaries will be involved in electronic markets. Finally, we briefly highlight several social and institutional factors that also may mitigate against the elimination of intermediaries. This broader perspective of the role of intermediaries in the exchange process calls for incorporating consumer-centric and institutional perspectives into the discussion of the evolution of electronic market structures.
Todays workflow management systems are only applicable in a secure and safe manner if the business process (BP) to be supported is well-structured and there is no need for ad hoc deviations at run-time. As only few BPs are static in this sense, this significantly limits the applicability of current workflow (WF) technology. On the other hand, to support dynamic deviations from premodeled task sequences must not mean that the responsibility for the avoidance of consistency problems and run-time errors is now completely shifted to the (naive) end user. In this paper we present a formal foundation for the support of dynamic structural changes of running WF instances. Based upon a formal WF model (ADEPT), we define a complete and minimal set of change operations (ADEPTflex) that support users in modifying the structure of a running WF, while maintaining its (structural) correctness and consistency. The correctness properties defined by ADEPT are used to determine whether a specific change can be applied to a given WF instance or not. If these properties are violated, the change is either rejected or the correctness must be restored by handling the exceptions resulting from the change. We discuss basic issues with respect to the management of changes and the undoing of temporary changes at the instance level. Recently we have started the design and implementation of ADEPTworkflow, the ADEPT workflow engine, which will make use of the change facilities presented in this paper.
Workflow Management Systems (WFMSs) automate the execution of business processes in environments encompassing large numbers
of users distributed over a wide geographic area and using heterogeneous resources. Current implementations allow the definition
and controlled execution of complex and long lived business processes as the basis for an enterprise-wide collaborative system
but, in most cases, the autonomy of the users is greatly restricted due to architectural and design considerations. In particular,
existing systems are built around a centralized server. As a result, users need to maintain an uninterrupted connection with
the server to perform the different tasks assigned to them. This is a severe restriction, especially when considering the
emergence of mobile computing, and the increase in use of laptops and small computers which are connected to the network only
occasionally and which will, undoubtedly, be the tool of choice for many users. This paper addresses the problem of supporting
disconnected workflow clients in large workflow management systems while still preserving the correctness of the overall execution
and allowing coordinated interactions between the different users regardless of their location.
In this paper we propose a foundational vision of e-Services, in which we distinguish between the external behavior of an e-Service as seen by clients, and the internal behavior as seen by a deployed application running the e-Service. Such behaviors are formally expressed as execution trees describing the interactions of the e-Service with its client and with other e-Services. Using these notions we formally define e-Service composition in a general way, without relying on any specific representation formalism.
This paper examines the opportunities and challenges related to data and process integration architectures in the context of Web Services. A primary goal of most enterprises in today's economic environment is to improve productivity by streamlining and aggregating business processes. This paper illustrates how integration architectures based on Web Services offer new opportunities to improve productivity that are expedient and economical. First, the paper introduces the technical standards associated with Web Services and provides business example for illustration. Abstracting from this example, we introduce a concept we call Process Aggregation that incorporates data aggregation and workflow to improve productivity. We show that Web Services will have a major impact on Process Aggregation, making it both faster and less expensive to implement. Finally, we suggest some research directions relating to the Process Aggregation challenges facing Web Services that are not currently being addressed by standards bodies or software vendors. These include context mediation, trusted intermediaries, quality and source selection, licensing and payment mechanisms, and systems development tools.
This paper introduces a framework for modeling and specifying the global behavior of e-service compositions. Under this framework, peers (individual e-services) communicate through asynchronous messages and each peer maintains a queue for incoming messages. A global "watcher" keeps track of messages as they occur. We propose and study a central notion of a "conversation", which is a sequence of (classes of) messages observed by the watcher. We consider the case where the peers are represented by Mealy machines (finite state machines with input and output). The sets of conversations exhibit unexpected behaviors. For example, there exists a composite e-service based on Mealy peers whose set of conversations is not context free (and not regular). (The set of conversations is always context sensitive.) One cause for this is the queuing of messages; we introduce an operator "prepone" that simulates queue delays from a global perspective and show that the set of conversations of each Mealy e-service is closed under prepone. We illustrate that the global prepone fails to completely capture the queue delay effects and refine prepone to a "local" version on conversations seen by individual peers. On the other hand, Mealy implementations of a composite e-service will always generate conversations whose "projections" are consistent with individual e-services. We use projection-join to reflect such situations. However, there are still Mealy peers whose set of conversations is not the local prepone and projection-join closure of any regular language. Therefore, we propose conversation specifications as a formalism to define the conversations allowed by an e-service composition. We give two technical results concerning the interplay between the local behaviors of Mealy peers and the global behaviors of their compositions. One result shows that for each regular language, its local prepone and projection-join closure corresponds to the set of conversations by some Mealy peers effectively constructed from . The second result gives a condition on the shape of a composition which guarantees that the set of conversations that can be realized is the local prepone and projection-join closure of a regular language.
To support fully automatic business cycles, information systems for electronic commerce need to be able to conduct negotiation automatically. In recent years, a number of general frameworks for automated negotiation have been proposed. Application of such frameworks in a specific negotiation situation entails selecting the proper framework and adapting it to this situation. This selection and adaptation process is driven by the specific characteristics of the situation. This paper presents a systematic investigation of there characteristics and surveys a number of frameworks for automated negotiation.
This paper brings some perspective to various concepts in computational reflection. A definition of computational reflection is presented, the importance of computational reflection is discussed and the architecture of languages that support reflection is studied. Further, this paper presents a survey of some experiments in reflection which have been performed. Examples of existing procedural, logic-based and rule-based languages with an architecture for reflection are briefly presented. The main part of the paper describes an original experiment to introduce a reflective architecture in an object-oriented language. It stresses the contributions of this language to the field of object-oriented programming and illustrates the new programming style made possible. The examples show that a lot of programming problems that were previously handled on an ad hoc basis, can in a reflective architecture be solved more elegantly.
Electronic hubs--Internet-based intermediaries that host electronic marketplaces and mediate transactions among businesses--are generating a lot of interest. Companies like Ariba, Chemdex, and Commerce One have already attained breathtaking stock market capitalizations. Venture capitalists are pouring money into more business-to-business start-ups. Even industrial stalwarts like GM and Ford are making plans to set up their own Web markets. As new entrants with new business models pour into the business-to-business space, it's increasingly difficult to make sense of the landscape. This article provides a blueprint of the e-hub arena. The authors start by looking at the two dimensions of purchasing: what businesses buy--manufacturing inputs or operating inputs--and how they buy--through systematic sourcing or spot sourcing. They classify B2B e-hubs into four categories: MRO hubs, yield managers, exchanges, and catalog hubs, and they discuss each type in detail. Drilling deeper into this B2B matrix, the authors look at how e-hubs create value--through aggregation and matching--and explain when each mechanism works best. They also examine the biases of e-hubs. Although many e-hubs are neutral--they're operated by independent third parties--some favor the buyers or sellers. The authors explain the differences and discuss the pros and cons of each position. The B2B marketplace is changing rapidly. This framework helps buyers, sellers, and market makers navigate the landscape by explaining what the different hubs do and how they add the most value.
With the advent and proliferation of the Internet many aspects of business and market activities are changing. New forms of intermediation also called cybermediaries are becoming increasingly important as a coordinator of interaction between buyers and sellers in the electronic market environment. Especially the overwhelming abundance of information offered by the Internet promotes the development of new intermediarie like malls, shopbots, virtual resellers etc. This paper provides a detailed overview of different new forms of cybermediation and illustrates their influence on consumer choice, firm pricing and product differentiation strategies.
Business process integration and automation (BPIA) has emerged as an important aspect of the enterprise computing landscape. Intra-enterprise application integration (EAI) as well as the inter enterprise integration (B2B) are increasingly being performed in the context of business processes. The integration scenarios typically involve distributed systems that are autonomous to some degree. From the BPIA perspective, the autonomy refers to the fact that the systems being integrated have their own process choreography engines and execute internal business processes that are private to them. In the case of B2B integration, the systems being integrated are fully autonomous, while various levels of autonomy exist in systems partaking in EAI. We present a new paradigm for business process integration. Our approach is based on a conversation model that enables autonomous, distributed BPM (Business Process Management) modules to integrate and collaborate. Our conversation model supports the exchange of multiple correlated messages with arbitrary sequencing constraints and covers the formatting of messages that are to be sent as well as the parsing of the messages that have been received. The crux of our conversation model is the notion of a conversation policy, which is a machine-readable specification of a pattern of message exchange in a conversation. Our model supports nesting and composition of conversation policies to provide a dynamic, adaptable, incremental, open-ended, and extensible mechanism for business process integration. We discuss the current implementation of this conversation model and early experience in applying the model to solve customer problems. The implementation utilizes distributed object technology.
We introduce the RT framework, a family of role-based trust management languages for representing policies and credentials in distributed authorization. RT combines the strengths of role-based access control and trust-management systems and is especially suitable for attribute-based access control. Using a few simple credential forms, RT provides localized authority over roles, delegation in role definition, linked roles, and parameterized roles. RT also introduces manifold roles, which can be used to express threshold and separation-of-duty policies, and delegation of role activations. We formally define the semantics of credentials in the RT framework by presenting a translation from credentials to Datalog rules. This translation also shows that this semantics is algorithmically tractable.
We present the design of a distributed authorization service which
parallels existing authentication services for distributed systems. Such
a service would operate on top of an authentication substrate. There are
two distinct ideas underlying our design: (1) the use of a language,
called generalized access control list (GACL), as a common
representation of authorization requirements; and (2) the use of
authenticated delegation to effect authorization offloading from an end
server to an authorization server. We present the syntax and semantics
of GACL, and illustrate how it can be used to specify authorization
requirements that cannot be easily specified by ordinary ACL. We also
describe the protocols in our design