Blockchain Papers

Victor Amaral de Sousa, Corentin Burnay, Monique Snoeck

No abstract is available for this record.

Nils Masuch, Elif Eryilmaz, Tobias Küster, Udo Pletat · 9 authors

No abstract is available for this record.

Antoni Olivé

No abstract is available for this record.

Florian Gräbe, Niclas Kannengießer, Sebastian Lins, Ali Sunyaev

Distributed Ledger Technology (DLT) enables a new way of inter-organizational collaboration via a shared and distributed infrastructure. Meanwhile, there is plenty of DLT designs (e.g., Ethereum, IOTA), which differ in their capabilities to meet use case requirements. A structured comparison of DLT designs is required to support the decision for an appropriate DLT design. However, existing criteria and processes are abstract or not suitable for an in-depth comparison of DLT designs. We select and operationalize DLT characteristics relevant for a comprehensive comparison of DLT designs. Furthermore, we propose a comparison process, which enables the structured comparison of a set of DLT designs according to application requirements. The proposed process is validated with a use case analysis of three use cases. We contribute to research and praxis by introducing ways to operationalize DLT characteristics and generate a process to compare different DLT designs accordingly to their suitability in a use case.

Gavriel Christofi

Nowadays, blockchain is one of the most popular and innovate technologies over the world. Although this technology appears for first time in the Bitcoin cryptocurrency, in recent years, a lot of researchers and industries from different fields such as banking, financial, supply chain management, etc. have given more involved than ever before. The blockchain is implemented in decentralized and distributed ledgers in peer-to-peer (p2p) networks where non-trusting peers can implement digital asset transactions without the need of central authority. Then, other peers in the network, according specific rules determined by the network, validate these transactions, insert them in the block and append the block in the chain (ledger). The key contribution for the proper operation of the blockchain is the consensus protocols. Through these protocols, all the peers in the network or the majority of them, they have to reach an agreement for a specific block in order to insert it in the chain based on different blockchains rules. In this master thesis, we will analyze in depth the general architecture of the blockchain and various consensus protocols that implemented in different blockchains in order to be able to improve the Delegated Byzantine Fault Tolerance (DBFT) consensus algorithm, which is used in the NEO blockchain technology. Finally, a development of a reputation mechanism is needed based on the improvement of the DBFT algorithm in order to measure the reputation of the peers for a specific day.

Shaul Kfir, Camille Fournier

We’ll see the same kind of Cambrian explosion we witnessed in the web world once we started using mutualized infrastructure in public clouds and frameworks. It took only three weeks to learn enough Ruby on Rails and Heroku to push out the first version of a management system for that brokerage. And that’s because I had to think only about the models, the views, and the controllers. The hardest part, of course, had to do with building a secure wallet.

Danning Sui, Gëzim Sejdiu, Damien Graux, Jens Lehmann

With the recent trend on blockchain, many users want to know more about the important players of the chain. In this study, we investigate and analyze the Ethereum blockchain network in order to identify the major entities across the transaction network. By leveraging the rich data available through Alethio's platform in the form of RDF triples we learn about the Hubs and Authorities of the Ethereum transaction network. Alethio uses SANSA for effcient reading and processing of such large-scale RDF data (transactions on Ethereum blockchain) in order to perform analytics e.g. finding top accounts, or typical behavior patterns of exchanges' deposit wallets and more.

Benedikt Kirpes, Micha Roon, Christopher Burgahn

The mobility sector experiences a fundamental shift to more connected, autonomous, shared and electric means of transportation. For an electric mobility system to function, an efficient and reliable electric vehicle charging network is required. The Open Charging Network, which is built and curated by the Share&Charge Foundation is a digital, open and decentralized infrastructure for operating and connecting assets of the e-mobility ecosystem like charge points and electric vehicles. In such a network validity and consistency of data are crucial. Since the underlying information system is designed based on distributed ledger technologies and distributed hash tables, also the validation of data for the respective key-value store should be implemented and executed in a distributed manner. In this paper, we contribute to the body of research by analyzing the current situation in distributed systems and presenting the design and development of a mechanism for a distributed data validation. We provide an outlook into the future implementation within the Open Charging Network, where the solution will be demonstrated in a suitable context. Further it will be evaluated regarding the primary requirement of data validity and secondary requirements such as availability, reliability and scalability.

Ioana Stănescu, Lenuța Alboaie, Andrei Panu

Blockchain has emerged as a trusted and secure distributed ledger for transactions while also being decentralised, distributed and its legitimacy not guaranteed by a trusted authority. Since the appearance of Bitcoin, Blockchain has known many implementations based on P2P architectures. This paper presents how the blockchain and smart contracts technologies can be integrated into the SwarmESB ecosystem. SwarmESB is a framework that helps building distributed applications, which benefit from privacy and scalability features. Our proposal will present the flexibility in building not only microservices based applications, but also decen-tralised applications employing blockchain and smart-contracts by modeling a sample Dapp.

Orlenys López‐Pintado, Luciano García‐Bañuelos, Marlon Dumas, Ingo Weber · 5 authors

Blockchain platforms, such as Ethereum, allow a set of actors to maintain a ledger of transactions without relying on a central authority and to deploy scripts, called smart contracts, that are executed whenever certain transactions occur. These features can be used as basic building blocks for executing collaborative business processes between mutually untrusting parties. However, implementing business processes using the low-level primitives provided by blockchain platforms is cumbersome and error-prone. In contrast, established business process management systems, such as those based on the standard Business Process Model and Notation (BPMN), provide convenient abstractions for rapid development of process-oriented applications. This article demonstrates how to combine the advantages of a business process management system with those of a blockchain platform. The article introduces a blockchain-based BPMN execution engine, namely Caterpillar. Like any BPMN execution engine, Caterpillar supports the creation of instances of a process model and allows users to monitor the state of process instances and to execute tasks thereof. The specificity of Caterpillar is that the state of each process instance is maintained on the (Ethereum) blockchain and the workflow routing is performed by smart contracts generated by a BPMN-to-Solidity compiler. The Caterpillar compiler supports a large array of BPMN constructs, including subprocesses, multi-instances activities and event handlers. The paper describes the architecture of Caterpillar, and the interfaces it provides to support the monitoring of process instances, the allocation and execution of work items, and the execution of service tasks.

Jong-Ki Lee

4차산업혁명시대에 블록체인기술이 각광 받고 있다

Emanuel Palm

This thesis presents an extension to Hyperledger Fabric, a private blockchain system, allowing historic transactions to be pruned without peer coordination. The feature is facilitated via pruning predicate functions, provided along any smart contracts a given system is desired to host. An evaluation of the extension demonstrates its impact, in terms of memory saved, for a specific asset delivery use case. It is concluded that the gains of pruning historic transactions from blockchain systems could yield significantly reduced storage requirements for some categories of applications, especially such with low transaction interdependency. It is also suggested that the deterministic consensus algorithms used by Hyperledger Fabric makes the transaction histories it may maintain not strictly required, meaning that the particular set of transactions that must survive pruning depend on what properties a blockchain is expected to maintain.

Tom Johansson, Viktor Charpentier

All human interaction can be depicted as exchanges. We exchange trivial information, feelings, assets and more. Valuable exchanges have one thing in common; they all require some degree of trust. In today’s society we rely on institutionalized trust when commencing an exchange of value. Typically, this role is filled by a vast ecosystem consisting of commercial banks, clearinghouses and other third parties. The recent rise of Bitcoin, Ethereum and consequent attention on the underlying technology, blockchain, questions the future of current ecosystem. This report aims at uncovering what blockchain is, what different implementations are currently available and how it would affect today’s ecosystem. It does so through semistructured interviews with actors within the current ecosystem as well as weighing in the views of blockchain evangelists. It highlights five key aspects that are crucial when implementing blockchain technology within the existing banking paradigm. Today’s organized societies require law and order which, to a large extent, is limited within the realm of public blockchain technology. With the insight of society’s infrastructural limitations, this paper argue that the current transaction system of our society favors a permissioned implementation with trusted nodes. Such a system would result in more efficient financial markets and lower costs of transacting. However, this paper acknowledge the virtues and reasons behind the rise of public blockchains. Given recent developments within the field and interesting concepts, the report does not dare to exclude a future of banking relying on public blockchain technology as the underlying database.

Hubert Ritzdorf, Karl Wüst, Arthur Gervais, Guillaume Felley · 5 authors

An internet user wanting to share observed content is typically restricted to primitive techniques such as screenshots, web caches or share button-like solutions. These acclaimed proofs, however, are either trivial to falsify or require trust in centralized entities (e.g., search engine caches). This motivates the need for a seamless and standardized internet-wide non-repudiation mechanism, allowing users to share data from news sources, social websites or financial data feeds in a provably secure manner. Additionally, blockchain oracles that enable data-rich smart contracts typically rely on a trusted third party (e.g., TLSNotary or Intel SGX). A decentralized method to transfer web-based content into a permissionless blockchain without additional trusted third party would allow for smart contract applications to flourish. In this work, we present TLS-N, the first TLS extension that provides secure non-repudiation and solves both of the mentioned challenges. TLS-N generates non-interactive proofs about the content of a TLS session that can be efficiently verified by third parties and blockchain based smart contracts. As such, TLS-N increases the accountability for content provided on the web and enables a practical and decentralized blockchain oracle for web content. TLS-N is compatible with TLS 1.3 and adds a minor overhead to a typical TLS session. When a proof is generated, parts of the TLS session (e.g., passwords, cookies) can be hidden for privacy reasons, while the remaining content can be verified.

Allan Third, John Domingue

Searching for information in distributed ledgers is currently not an easy task, as information relating to an entity may be scattered throughout the ledger with no index. As distributed ledger technologies become more established, they will increasingly be used to represent real world transactions involving many parties and the search requirements will grow. An index providing the ability to search using domain specific terms across multiple ledgers will greatly enhance to power, usability and scope of these systems.

Vipin K. Suri

Business support services are internal services required by various business units within a company to support their operations and meet their strategic business objectives.The strategies for sourcing, structuring and governance of business support services depend on the nature of work being performed and who is being served.In recent decades, companies have been using various service delivery models, such as decentralization, centralization, shared services, offshoring and outsourcing to deliver these services.Through these models of service delivery companies manage their business support services not only as stand-alone functions but also as sub-functions such as payroll, general ledger accounting, accounts payable, employee services and purchasing, which are carried out within the departments of Finance, HR, IT, Supply Chain Management and Facilities Management.These sub-functions within functions deliver services such as payment of employees, bookkeeping, payment of vendors, employee records and processing of purchase orders.Business support services are internal services that are required by various business units within a company.These internal services, in turn, support the company's operations in meeting the company's strategic business objectives.The models applied to deliver these services have changed significantly.Current models include decentralization, centralization, shared services, offshoring and

Waleed W. Smari, Antonio Montero Navarro, William K. McQuay

During the past two decades, we have seen rising interest in computer-supported collaboration and, with the advent of the Web 2.0 and semantic technologies, increased importance for collaborative work. Worldwide, people expect unlimited access to information within and across cultures. Social networking continues to expand and impact collaboration approaches at the personal and enterprise levels. As a result, the computer-supported collaboration research community has turned its attention to the study of human social behavior from records such as blogs, wikis, social media, and social networking sites 1. The desire for mobile and pervasive connectivity is pushing expansion of an ever growing wired and wireless high speed backbone that globally combines computing, sensing, and communication technologies. Annually, new classes of mobile devices are added to the traditional desktop, laptop, tablet, and smartphones. However, computer-based collaboration encompasses complex hardware and software issues that have been in the focus of the research community for a long time 2. In 1981, Johnson-Lenz coined the term groupware as ‘intentional group processes plus software to support them’ 3. By 1988, the term computer-supported cooperative work was defined as ‘a scientific discipline guiding the design and development of groupware in a meticulous and appropriate way’ 4. Computer-supported cooperative work (CSCW) is a multidisciplinary discipline that encompasses technical, human, and social factors that can vary its implementations depending on the context, culture, organization, and country that apply it 5. As collaborative/cooperative applications evolved, important challenges also arose for developers 6. As a result, significant on-going research works address topics such as collaboration systems infrastructure, human systems, collaboration work and processes, and unique domain-specific issues. The field of infrastructure is one of the most active areas in computer-supported collaboration, with research focused on underlying technologies such as cloud computing, big data, service-oriented architectures, smart networks, and grids. Advanced infrastructure technologies offer a vision of resources (networks, computational servers, storage, search engines, collaboration tools and applications, etc.) as a service, with greater ease to collaborate while lowering cost. The Internet of Things (IoT) captures the growing importance of sensor swarms and collaborative devices that are often attached to one's smartphone or tablet. At the same time, there are new complementary challenges for privacy and security as we attempt to understand how to handle trust in complex systems and how to measure trustworthiness in human-to-human, human-to-machine, and machine-to-machine collaborations. The field of human systems focuses on the human component in collaboration such as coordination and cooperation mechanisms, cultural and psychological aspects, natural languages, human-machine interaction and interfaces, human centric aspects of trust and trustworthiness, cognitive engineering, and user-centered design. The field of collaboration work and processes focuses on aspects that traditionally relate to management and business but gradually have been considered by the software engineering area, such as virtual and remote project coordination, distributed team management, workflows, coordination, distributed and virtual organizations, and distributed design and development. Finally, the domains where computer-based collaboration can be applied continue to grow and are almost endless. Social media, knowledge management, e-learning, financial systems, simulation environments, decision making, design and engineering, logistics, e-business, telemedicine, public health, and emergency and disaster response are some examples of these domains. The annual International Conference on Collaboration Technologies and Systems, held since 1999, comes in the mid of these exciting developments. The conference has also produced special journal issues in recent years and this is one of them. This special issue contains eleven papers representing recent advances in the areas of the infrastructure, operation, evaluation, and application of collaboration systems. These papers were carefully selected from the 2012 International Conference on Collaboration Technologies and Systems (CTS 2012), which was held at the Westin Westminster Hotel, Denver, Colorado, USA, on 21–25 May, 2012 7 and the 2013 International Conference on Collaboration Technologies and Systems (CTS 2013), which was held at the Sheraton San Diego Hotel & Marina, San Diego, California, USA, on 20–24 May, 2013 8. Selected papers from the conference were invited for extended submission based on the conference technical program committee and the track organizers recommendations. In addition and in order to provide a wider overview of the current research in collaboration related topics, an open Call for Papers was publicly announced and distributed. In response, additional papers were received with a total of eighteen papers submitted for consideration. The complete set of submissions went through three rigorous review cycles, with three to six reviews per paper per cycle. Upon the conclusion of the review process, the eleven submissions that received the highest review ratings were accepted for publication in this special issue. The papers published in this special issue can be classified under three groups: collaborative system design methodologies, security and trust, and collaborative applications. The selected papers in each of these groups are briefly introduced in this section. There are six manuscripts that fall under this category, which covers a wide range of issues, approaches, and solutions. Drabble 9 presents an overview of the Cassandra Analysis and Planning System (CAPS) collaborative design tool kit, which provides designers with the capabilities to identify the direct effects of their own decisions and their indirect effects on the designs of others. The CAPS provides capabilities for reasoning with both quantitative and qualitative constraints and employs two dependency reasoning engines—one handles quantitative values and the other controls qualitative ones. CAPS supports a dynamic design process which identifies the most important design decisions, alerts the impacted designers, and supports a mitigation process to deal with any issues. The paper describes the CAPS architecture and an initial evaluation against a large collaborative task involving the design of a helicopter's electrical, hydraulic, structural, and mechanical systems. Tanaka et al. 10 study the effects real-time avatars had on distant communications when the avatars served as a substitute for videos in distributed environments. The paper discusses two experiments involving videos, photos, or avatars to supplement voice communications. In the first experiment, the subjects watched a conversation partner's video, avatar, photo, or nothing when speaking to the distant partner. The trials were made separately to observe the effects of motion and appearance on the frequency of pauses and speed of speaking. In the second experiment, the researchers compared avatar chat and a tele-operated robot conferencing to find how a physical embodiment influenced the degree of smoothness of speech. Traditionally, in distributed collaborative systems, video connections have been considered unimportant to effective distant communication. Dorn and Taylor 11 investigate the adaptability of the collaboration structure based on an analysis framework consisting of aspects such as behavior, asynchrony, state, and execution. They discuss seven distinctively different collaboration patterns in terms of those aspects. These collaboration patterns and resulting insights into their inherent adaptability may guide design decisions and trade-off analyses for the development of collaborative environments. The collaboration pattern construct is an extension of design pattern concepts and mechanisms from the software architecture domain. The success of software architecture description languages 20 led the authors to investigate a modeling approach for collaboration topologies and the development of a human Architecture Description Language (hADL) for specifying adaptation authority or flexibility conditions. In Davoust et al. 12, the authors define, classify, and characterize distributed wikis. They have identified three classes of distributed wiki systems, each using a different collaboration model and distribution scheme: highly available wikis, decentralized social wikis, and federated wikis. They have classified existing distributed wikis according to these classes and detail their underlying complexities and social and technical motivations. Davoust et al. 13 address the challenge that existing wiki systems, such as Wikipedia, depend on a centralized authority and cannot easily accommodate multiple points of view. The authors present P2Pedia, a social peer-to-peer wiki system, where users have their own local repository and can collaborate by creating, discovering, editing, and sharing pages with their peers but without synchronizing them. Multiple versions of each page can thus coexist on each repository and across the network, which allows for multiple points of view. Browsing or searching the wiki can yield multiple page versions. The authors describe an experimental study where the system was deployed for academic writing exercises, and the results are analyzed to demonstrate this collaboration approach. Missikoff et al. 14 present an end-to-end framework based on an open, collaborative approach for developing and maintaining business domain ontologies. While modern virtual enterprises require the definition of a common, agreed to, and shared conceptual basis that is captured in a reference ontology, no single methodology has been recognized as the primary solution for building ontologies. The authors propose a method for building domain ontologies, which is capable of integrating in one single software framework the features of cooperative participation, shared agreement, multilevels of formalism, and reuse of knowledge. The authors' methodology is characterized by a social participation approach that allows a community of practice, including knowledge engineers, domain experts, and ontology stakeholders to cooperate to produce conceptual models and reach consensus on their suitability while providing formal encoding into a computational ontology. Security and privacy issues in collaboration environments continue to be a major concern. We have three manuscripts that address some of the contemporary concerns. In Aldini et al. 15, the authors have proposed a collaborative framework for checking Android applications for malware by generating probabilistic behavior contracts. Repackaged Android applications are based on genuine applications, but they can include some hidden malwares to access private data or user credit information. The proposed framework performs analysis of the app's behavior at run-time from a contract that is built dynamically from monitoring real world usage. The contract specifies the set of legal actions that can be performed by an application. In the proposed framework, application contracts are generated dynamically by a central server that merges execution traces that are collected and shared continuously by collaborative users executing the application. Because the contract is built by monitoring real user behaviors, it is possible to detect misbehaviors that may not be noticed through static analysis alone. Kong et al. 16 present a technique for indoor location of mobile devices using Bluetooth wireless signal strength. The proposed method treats locations as fuzzy sets and fuzzifies the signal strength to define set membership. Membership values are then fused from multiple sources using a rules engine to deduce location values. The principal benefits of this technique include that it requires little or no calibration, can be used with widely available commercial devices, and places more attention on location information such as a room and floor of a building rather than coordinates. In Tang et al. 17, the authors address the need for extensions to the role-based access control model as cloud service providers expand user activities for cross-tenant interaction. Currently, most cloud service providers isolate user activities and data within a single tenant boundary. It is anticipated that this situation will evolve to foster cross-tenant collaboration supported by Authorization as a Service (AaaS). At present, there is no widely accepted model for cross-tenant authorization. The authors have built on an existing informal multi-tenancy authorization system (MTAS) 21, formalized the MTAS model, and proposed extensions for finer-grained cross-tenant trust. They have demonstrated the utility and feasibility of MTAS by means of an example policy specification, developed a prototype system, and conducted experiments on the prototype. The design and development of collaboration applications are important to respond to society's needs and solutions. In this special issue, there are two papers that apply. Lang and Fink 18 address rival machine scheduling of one or more homogeneous machines by autonomous agents. Machine scheduling by itself is computationally complex, and the presence of autonomous agents makes the problem more difficult. Autonomous agents pursue their own goals, act noncooperatively, and might not be willing to reveal information due to privacy concerns. To overcome the conflict of interests and prevent strategic interactions, the authors present a negotiation protocol to facilitate the coordination of noncooperative agents. Pani et al. 19 present the design and evaluation of a patient-centric collaborative tele-rehabilitation framework aimed at supporting a multidisciplinary team in the follow-up of domiciliary patients. The proposed framework builds on the experience of a clinical trial that exploited a novel tele-rehabilitation device not originally intended to support collaborative scenarios. The authors argue that collaborative technology in healthcare represents an important way to improve the quality of the care services and at a reduced cost. The authors conducted semi-structured interviews with a panel of experts to evaluate the proposed approach. Based on the papers submitted to and accepted in this special issue, we can draw some interesting conclusions. Computer-supported collaboration is in the mainstream interest of the research community. It is utilized in the everyday way of work of individuals, communities, and organizations. This usage is identifying subtle problems that have to be solved by researchers and practitioners in academia and industry. Technological, procedural, human, and domain-dependent issues have to be addressed by works such as those presented in this special issue. However, because computer-supported collaboration is being used in vastly different domains, the problems that this use identify are of very diverse nature. As we have seen, the papers published in this special issue address collaborative design, real time avatars, collaboration patterns, distributed wikis, business ontologies, malware detection, location of mobile devices, access control, autonomous agents, and tele-health. We anticipate this trend to continue as these systems and technologies get more pervasive and experience wider usage in numerous sectors and application domains. In some cases, the issues addressed by computer-supported collaboration fall within the focus of interest of other well-established areas of computer science and engineering such as operating systems, software engineering, information systems, or telecommunications,. In other cases, they are more related to organizational and business, sociology, psychology, anthropology, or human factors. If computer-supported collaboration is to be a discipline on its own, the key issues that describe it have to be identified. It is commonly accepted that computer-supported collaboration is not just a narrow and deep computing discipline but, on the contrary, is a broad and multidisciplinary field that cuts across many computing and noncomputing areas. In our opinion, the definition of the discipline of computer-supported collaboration has to be one of the hot topics of the research community in the short term. Thus, the development of the computer-supported collaboration body of knowledge could help to define this discipline. We hope that works like this special issue promote the interest for this discipline and its research topics. The guest editors of this special issue would like to express their deep gratitude to all authors, external reviewers, and Geoffrey Fox for their efforts in making this special issue possible. Moreover, they wish to thank all of the external reviewers who contributed at different levels to this special issue: Marie-Hélène Abel, Gail-Joon Ahn, Mortaza S. Barg, Louise Barkhuus, Sanat K. Bista, Christos Bouras, Mario Cannataro, Kyle Chard, Giuliana Dettori, Schahram Dustdar, Ana María Fernández-Pampillón, Maria Grazia Fugini, Ronald Hartung, Andrea J. Hester, Douglas Hodson, Claudia Ignat, James Joshi, Malik Ahmad Kamran, Kyoung-Yun Kim, Gregorij Kurillo, Tanu Malik, Cristina Manresa, Laurent Moccozet, Pascal Molli, James Myers, Grzegorz J. Nalepa, Mads Nygaard, Francesco Palmieri, Daniel Perry, T.K. Prasad, Wolfgang Prinz, Paolo Renna, Vassil Roussev, Filippo A. Salustri, Liliana P. Santacruz, Antonio Sarasa, José Luis Sierra, Hala Skaf-Molli, Irena Spasic, Anna Squicciarini, Kyle Stewart, Julianne Stiller, Jeffrey Stuckman, Hassan Takabi, Giordano Tamburrelli, Srikumar Venugopal, Bin Wang, Liu Yang, Chee Shin Yeo, Dimitrios Zissis, and Urko Zurutuza.

Alex Norta, Lixin Ma, Yucong Duan, Addi Rull · 6 authors

Meaningfully automating sociotechnical business collaboration promises efficiency-, effectiveness-, and quality increases for realizing next-generation decentralized autonomous organizations. For automating business-process aware cross-organizational operations, the development of existing choreography languages is technology driven and focuses less on sociotechnical suitability and expressiveness concepts and properties that recognize the interaction between people in organizations and technology in workplaces. This gap our suitability- and expressiveness exploration fills by means of a cross-organizational collaboration ontology that we map as a proof-of-concept evaluation to the eSourcing Markup Language (eSML). The latter we test in a feasibility case study to meaningfully support the automation of business collaboration. The developed eSourcing ontology and eSML is replicable for exploring strengths and weaknesses of other choreography languages.

Paulo Leitão

No abstract is available for this record.

Omar Khadeer Hussain, Elizabeth Chang, Farookh Khadeer Hussain, Tharam S. Dillon

Risk is present in almost every activity. Alternately speaking, almost every activity may have some undesired outcomes which the person doing the activity hopes that they do not occur when it undertakes that particular activity. The quantification of those undesired outcomes can be termed as Risk. Risk is associated with Trust, Security and Privacy. Risk is also associated with transactions, businesses, information systems, environments, networks, partnerships, etc. Generally speaking, Risk signifies the likelihood of financial loss, human casualties, business destruction and environmental damages. It is important to define Risk according to the context of the transaction in order to understand and analyse it better. In the literature Risk has been defined and discussed in areas such as security, health, finance, environment and social life, but there is no systematic study of Risk in decentralized communications, which involves e-business, computer networks and service oriented environments. Hence in this paper, a particular attention is given to define and analyse Risk in the area of Peer-to-Peer business communications, where Risk is every individual and organization?s concern. Also in this paper we develop a risk indicator scale and develop a methodology by which the Riskiness of the peer can be rated according to its behaviour in an interaction. Risk indicator gives an early warning to the party involved and helps avoid disasters.

J.M. Marques, Leandro Navarro, Τhanasis Daradoumis

Asynchronous collaborative applications and systems have to deal with complexities associated with interaction nature, idiosyncrasy of groups and technical and administrative issues. Inclusion of requirements derived from them is costly (in time, resources and economically). Existing solutions addresses asynchronous collaboration via simplification of requirements and by using centralized models. In this paper we present LaCOLLA, a fully decentralized infrastructure for building collaborative applications that provides general purpose collaborative functionalities. The provision of those functionalities will avoid applications deal with most of complexities derived from groups and its members, what will help inclusion of collaborative aspects. The implementation of LaCOLLA follows the peer-to-peer paradigm and pays special attention to autonomy of its members and to self-organization of the components of the infrastructure. Another key aspect is that resources (e.g. storage) and services (e.g. authorization) are provided by its members (avoiding dependency from agents not belonging to group).

Francisco Matias Cuenca-Acuna, Thu D. Nguyen

We consider the problem of deploying and managing federated services that run on federated systems spanning multiple collaborative organizations. In particular, we present a peer-to-peer framework targeted to the construction of self-managing services that automatically adjust the number of service components and their placements in response to changes in the system or client loads. Our framework is completely decentralized, depending only on a modest amount of loosely synchronized global state. More specifically, our framework is comprised of a set of per-node monitoring agents and per-service-component management agents that periodically exchange information about the state of the system and of the service with each other using a gossiping protocol. Each management agent then periodically searches for configurations that are better than the current one according to an application model and explicit performance and availability targets. On finding a better configuration, an agent will enact the new configuration after a random delay to avoid possible collisions. We evaluate our framework by studying a prototype UDDI service. We show that while agents act autonomously, the service rapidly reaches a stable and appropriate configuration in response to system dynamics.

Frank Dignum, G.J.P.M. Houben

This paper describes a new approach to design modern information systems that offer an integrated access to the data and knowledge that is available in local applications. By integrating the local data management activities into one transparent information distribution process, modern organizations can offer better support for its workers in the execution and coordination of their work activities. Observing practical applications of decentralized, autonomous and heterogeneous information systems we see deficiencies in currently available approaches to model such information systems. They do not acknowledge the pivotal role that (informal) communicating workers play in the context of an entire organization. The interaction between the members of social and informal groups of employees makes it possible that (in many of today’s information-intensive enterprises) the local structured procedures can be effectively and flexibly integrated into global work processes supporting the business goals. Traditional design techniques concentrate on either the structured local procedures (and its local database applications), the structured global process (and its global business goals), or the informal (less structured) communication between individuals. We suggest to combine an activity-based model (suited to describe the structured parts of the processes) with a goal- or conversation-based model to tie the different elements together. Using an agent architecture we show that it is possible to implement this integrated approach. The different types of cooperating agents support the individual workers by assessing the goal of the activity, the applicability of the standard procedure, and the availability of alternative knowledge and information in order to supply the necessary information.