Handbook of Research on P2P and Grid Systems for Service-Oriented Computing: Models, Methodologies and Applications (2 Volumes)

Handbook of Research on P2P and Grid Systems for Service-Oriented Computing: Models, Methodologies and Applications (2 Volumes)

Nick Antonopoulos (University of Derby, UK), Georgios Exarchakos (University of Surrey, UK), Maozhen Li (Brunel University, UK) and Antonio Liotta (Technical University of Eindhoven, The Netherlands)
Release Date: January, 2010|Copyright: © 2010 |Pages: 1342
ISBN13: 9781615206865|ISBN10: 1615206868|EISBN13: 9781615206872|DOI: 10.4018/978-1-61520-686-5


Effectively, the two fields of peer-to-peer computing and grid computing collectively form the de facto basis for the methodologies and techniques that need to be used to develop performance-driven service-oriented software platforms capable of satisfying key aspects of quality of service.

The Handbook of Research on P2P and Grid Systems for Service-Oriented Computing: Models, Methodologies, and Applications addresses the need for peer-to-peer computing and grid paradigms in delivering efficient service-oriented computing. This critical mass of the most sought after research serves as a collection of chapters facilitating a broad understanding of the subject matter useful to researchers and doctoral students working specifically in the deployment, implementation, and study of related topics including distributed computing, software engineering, Web services, and modeling of business processes.

Topics Covered

The many academic areas covered in this publication include, but are not limited to:

  • Collaborative Scientific Conceptual Change
  • Community of Research
  • Distributive Cognitive Processing
  • E-Collaborative Knowledge Construction
  • Human-Computer Interaction
  • Human-Human Interaction
  • Scripting Computer-Supported Collaborative Learning
  • Social Web
  • Transactive Memory
  • Virtual Learning Environments

Reviews and Testimonials

This handbook aims to address the need for more literature onto the applicability and use of P2P and Grid computing techniques for delivering efficient service-oriented computing.

– Nick Antonopoulos, Georgios Exarchakos, Maozhen Li, Antonio Liotta

Table of Contents and List of Contributors

Search this Book:
Editorial Advisory Board
Table of Contents
Omer F. Rana
Nick Antonopoulos, Georgios Exarchakos, Maozhen Li, Antonio Liotta
Chapter 1
Danny Hughes, Geof Coulson, James Walkerdine
Peer-to-peer file sharing has become popular for many kinds of resource location and distribution applications including file sharing, distributed... Sample PDF
A Survey of Peer-to-Peer Architectures for Service Oriented Computing
Chapter 2
Heba Kurdi, Maozhen Li, H. S. Al-Raweshidy
Advances in Grid computing are stimulating the emergence of novel types of Grids. Accessible Grids, manageable Grids, interactive Grids and personal... Sample PDF
Taxonomy of Grid Systems
Chapter 3
Lu Liu, Duncan Russell, Jie Xu
Peer-to-peer (P2P) networks attract attentions worldwide with their great success in file sharing networks (e.g., Napster, Gnutella, BitTorrent, and... Sample PDF
Peer-to-Peer Search Techniques for Service-Oriented Computing
Chapter 4
Carlos Abalde, Víctor M. Gulías, Javier París
Much recent work on building scalable peer-to-peer (P2P) systems has focused on distributed hash tables (DHTs), which have become in a powerful... Sample PDF
A Survey of Efficient Resource Discovery Techniques on DHTs
Chapter 5
Amitava Biswas, Suneil Mohan, Rabi Mahapatra
Searching is likely to be the next most important service on the Internet after communication. At present centralized Internet search engines can... Sample PDF
Semantic Technologies for Distributed Search P2P Networks
Chapter 6
Tran Vu Pham, Lydia M.S. Lau, Peter M Dew
Supporting global scientific collaborations are becoming more important due to the increasing complexity of modern scientific problems as well as... Sample PDF
Grid, P2P and SOA Orchestration: An Integrated Application Architecture for Scientific Collaborations
Chapter 7
Elias S. Manolakos, Demetris G. Galatopoullos
The vision of pervasive computing is to create and manage computational spaces where large numbers of heterogeneous devices collaborate... Sample PDF
Service-Oriented Architectures for Pervasive Computing
Chapter 8
Farag Azzedin, Mohamed Eltoweissy, Salman Ahmad Khwaja
The P2P computing is one of the technologies that is having a significant impact on the way Internet-scale systems are built. It is well established... Sample PDF
Overview of Service Oriented Architecture for Resource Management in P2P Systems
Chapter 9
Carlos Kamienski, Ramide Dantas, Djamel Sadok, Börje Ohlman
The authors use P2P communications for building a powerful service oriented architecture capable of orchestrating advanced services. Underlying... Sample PDF
Managing the Future Internet: Services, Policies and Peers
Chapter 10
P2P Network Management  (pages 226-244)
Chunsheng Ni, Jilong Wang
Peer-to-Peer (P2P) technology has been widely applied in Internet application systems, especially in sharing large video files among multiple user... Sample PDF
P2P Network Management
Chapter 11
Carmelo Ragusa
Over the past years we have witnessed a shift in the market towards service orientation. Companies in the coming service market need to be extremely... Sample PDF
Business Grids, Infrastructuring the Future of ICT
Chapter 12
Eddy Caron, Frédéric Desprez, Franck Petit, Cédric Tedeschi
Within distributed computing platforms, some computing abilities (or services) are offered to clients. To build dynamic applications using such... Sample PDF
Peer-to-Peer Service Discovery for Grid Computing
Chapter 13
Jochen Furthmüller, Oliver P. Waldhorst
Grid computing offers exciting possibilities for mobile consumer devices. The sharing of resources makes new, demanding applications feasible and... Sample PDF
Survey on Grid Computing on Mobile Consumer Devices
Chapter 14
Moisés R.N. Ribeiro, Marconi P. Fardin, Helio Waldman
The data transport structure of the modern networks is moving toward a model of high-speed packet/frame/timeslot capable... Sample PDF
P2P in Scalable Cross-Layer Control Planes of Next Generation Networks
Chapter 15
George V. Popescu
Recently a new category of communication network paradigms has emerged: overlay networks for content distribution and group communication... Sample PDF
Distributed Indexing Networks for Efficient Large-Scale Group Communication
Chapter 16
Chunjiang Zhao, Junwei Cao, Huarui Wu, Weiwei Chen
The data grid integrates wide-area autonomous data sources and provides users with a unified data query and processing infrastructure. Adaptive data... Sample PDF
Adaptive Query Processing in Data Grids
Chapter 17
Ryota Egashira, Akihiro Enomoto, Tatsuya Suda
In Service-Oriented Computing, service providers publish their services by deploying service components which implement those services into a... Sample PDF
Distributed and Adaptive Service Discovery Using Preference
Chapter 18
Mohammed Hawa
Cooperation incentives have been proposed as an effective solution to various problems that plague Peer-to-Peer (P2P) and Computational Grid systems... Sample PDF
Cooperation Incentives: Issues and Design Strategies
Chapter 19
Liangxiu Han
This chapter identifies challenges and requirements for resource sharing to support high performance distributed Service-Oriented Computing (SOC)... Sample PDF
Exploiting P2P and Grid Computing Technologies for Resource Sharing to Support High Performance Distributed System
Chapter 20
Marco A.S. Netto, Rajkumar Buyya
One of the promises of Grid Computing is to enable the execution of applications across multiple sites. Several multi-site applications require... Sample PDF
Resource Co-Allocation in Grid Computing Environments
Chapter 21
Daniel M. Batista, Nelson L.S. da Fonseca
The fluctuation in resource availability, as well as the uncertainties in relation to requirements for applications, call for the implementation of... Sample PDF
Self-Adjustment for Service Provisioning in Grids
Chapter 22
Ziliang Zong, Xiaojun Ruan, Adam Manzanares, Kiranmai Bellam, Xiao Qin
High performance Grid platforms and parallel computing technologies are experiencing their golden age because of the convergence of four critical... Sample PDF
Improving Energy-Efficiency of Computational Grids via Scheduling
Chapter 23
Bart De Vleeschauwer, Filip De Turck, Bart Dhoedt, Piet Demeester
This chapter discusses the use of peer-to-peer overlay networks to route around failures and congestion points in the Internet. The motivation for... Sample PDF
Dynamic Overlay Networks for Robust and Scalable Routing
Chapter 24
Florin Pop
This chapter presents a fault tolerant framework for the applications scheduling in large scale distributed systems (LSDS). Due to the specific... Sample PDF
A Fault Tolerant Decentralized Scheduling in Large Scale Distributed Systems
Chapter 25
Vassilios V. Dimakopoulos, Spiridoula Margariti, Mirto Ntetsika, Evaggelia Pitoura
Maintaining multiple copies of data items is a commonly used mechanism for improving the performance and fault-tolerance of any distributed system.... Sample PDF
Data Replication in P2P Systems
Chapter 26
Anwitaman Datta, Di Wu, Liu Xin, Adam Wierzbicki
Peer-to-Peer (P2P) storage systems leverage the combined storage capacity of a network of storage devices (peers) contributed typically by... Sample PDF
Maintaining Redundancy in Peer-to-Peer Storage Systems
Chapter 27
Dimka Karastoyanova, Frank Leymann
The current trend in Service Oriented Computing (SOC) is to enable support for new delivery models of software and applications. These endeavours... Sample PDF
Making Scientific Applications on the Grid Reliable Through Flexibility Approaches Borrowed from Service Compositions
Chapter 28
Ciprian Dobre
The field of modeling and simulation was long seen as a viable alternative to develop new algorithms and technologies and to enable the development... Sample PDF
A General Framework for the Modeling and Simulation of Grid and P2P Systems
Chapter 29
Bin Li, Lee Gillam
Grid computing continues to hold promise for the high-availability of a wide range of computational systems and techniques. It is suggested that... Sample PDF
Grid Service Level Agreements Using Financial Risk Analysis Techniques
Chapter 30
Lican Huang
The currently two types of main P2P technologies–unstructured and structured approaches do not care about the semantic meaning of the nodes. They do... Sample PDF
Virtual Hierarchical Tree Grid Organizations (VIRGO)
Chapter 31
Simon Miles, Nir Oren, Michael Luck, Sanjay Modgil, Felipe Meneguzzi, Nora Faci, Camden Holt, Gary Vickers
Electronic contracts mirror the paper versions exchanged between businesses today, and offer the possibility of dynamic, automatic creation and... Sample PDF
Electronic Business Contracts Between Services
Chapter 32
Adam Wierzbicki, Tomasz Kaszuba, Radoslaw Nielek
Peer-to-Peer (P2P) and Grid systems serve whole communities of users, and are thus good examples of information systems that should realize social... Sample PDF
Trust and Fairness Management in P2P and Grid Systems
Chapter 33
Karaoglanoglou Konstantinos, Helen Karatza
The significance of efficient security mechanisms in P2P and Grid systems is unquestionable, since security is considered to be a quality of service... Sample PDF
Trust Calculation and Management in P2P and Grid Systems
Chapter 34
Rehab Alnemr, Matthias Quasthoff, Christoph Meinel
Business often develop proprietary reputation systems for their community, with the side effect of locking users into that service if they wish to... Sample PDF
Taking Trust Management to the Next Level
Chapter 35
Hoon Wei Lim
Public key infrastructure (PKI) is presently deployed in most grid implementations. Existing PKI-based grid systems make extensive use of public key... Sample PDF
Designing Grid Security Infrastructures Using Identity-Based Cryptography
Chapter 36
Guillaume Pierre, Steen Maarten van
Many large-scale distributed applications rely on collaboration, where unrelated users or organizations share their resources for everyone’s... Sample PDF
Enforcing Fairness in Asynchronous Collaborative Environments
Chapter 37
G. Marchetto, M. Papa Manzillo, L. Torrero, L. Ciminiera, F. Risso
The idea of sharing resources across the network has become very popular during the last few years, leading to a diversified scenario in which... Sample PDF
Service Providers Indexing Using P2P Systems
Chapter 38
Aldo Campi, Franco Callegati
This chapter advocates migrating sufficient functionality into the network as to allow direct support to grid computing services. This approach is... Sample PDF
SIP Protocol for Supporting Grid Computing
Chapter 39
Matthew Adigun, Johnson Iyilade, Klaas Kabini
The service-oriented computing paradigm is based on the assumption that existing services can be put together in order to obtain new composite... Sample PDF
Agent-Based Infrastructure for Dynamic Composition of Grid Services
Chapter 40
Antonio Manzalini, Roberto Minerva, Corrado Moiso
This chapter describes motivations and characteristics of a novel service platform based on P2P technology for delivering Telecommunication and ICT... Sample PDF
Exploiting P2P Solutions in Telecommunication Service Delivery Platforms
Chapter 41
Malohat Ibrohimovna, Sonia Heemstra de Groot
A personal network (PN) is a network of a user’s personal devices and services, cooperating with each other independently of their geographical... Sample PDF
Fednets: P2P Cooperation of Personal Networks Access Control and Management Framework
Chapter 42
Paul Grace, Danny Hughes, Geoff Coulson, Gordon S. Blair, Barry Porter, Francois Taiani
Grid computing is becoming increasingly pervasive; sensor networks and mobile devices are now connected with traditional Grid infrastructure to form... Sample PDF
Overlay-Based Middleware for the Pervasive Grid
Chapter 43
A. R. Razavi, P. Krause, S. Moschoyiannis
Current research and development in ICT has opened new opportunities and threats for both large corporations and SMEs alike. Many SMEs see the new... Sample PDF
Digital Ecosystems: Challenges and Proposed Solutions
Chapter 44
Juan Pedro Muñoz-Gea, Josemaria Malgosa-Sanahuja, Pedro Jose Piñero-Escuer, Joan García-Haro
Thanks to the technological development, the production of multimedia content is no longer restricted to content providers. End-users communities... Sample PDF
Providing VoD Services in Community Networks Using P2P Technology
Chapter 45
Dana Petcu, Georgiana Macariu, Alexandru Cârstea, Marc Frîncu
Service-oriented computing is an interesting paradigm not only for building business applications but also for scientific applications requiring a... Sample PDF
Service-Oriented Symbolic Computations
Chapter 46
Corinna Schmitt, Georg Carle
Today the researchers want to collect as much data as possible from different locations for monitoring reasons. In this context large-scale wireless... Sample PDF
Applications of Wireless Sensor Networks
About the Contributors


1. Introduction & justification

Service-oriented computing is a popular design methodology for large scale business computing systems. Its underpinning principle is that of modelling a business process as a re-usable service entity that can be connected to a series of other physically distributed services in order to realise a set of predetermined specifications. Interest in further researching and applying the service oriented approach has exponentially increased in the past few years with the development of the Service Oriented Architecture (SOA) and other competing frameworks. A significant number of companies aim to reap the benefit of cost reduction by realising B2B and B2C processes on large-scale SOA-compliant software system platforms. This interest has also been compounded and further strengthened by the massive increase of e-commerce through the online selling of e-content from MP3 music and videos to services and access to specialised content and applications. This phenomenon is bound to continue in the future as big content providers such as music and film production companies forge partnerships with ISPs for on-demand, cost-efficient global content distribution over home broadband connections.

Traditionally, service-oriented computing research has focused on: a) the accurate mapping of real business logic onto software service objects, b) service inter-linking and workflow/transaction management and c) the interfaces and orchestration of the whole scheme by the underlying operating systems and physical hardware. However, this emphasis is quickly shifting towards researching into computing platforms that are capable of supporting this kind of processing. Due to the competitive nature of the aforementioned services, such a platform should be capable of providing a guaranteed quality of service to the customers of the participating businesses. This quality has four dimensions:

    1. Efficiency: The execution and coordination of the realised processes is optimised in terms of data traffic and latency. Data traffic stemming from user queries and downloads is the main cost factor of online content providers and thus its optimisation is a standard long term goal of such businesses. Latency is arguably one of the most important factors affecting customer satisfaction and therefore it should also be within specified acceptable limits.

    2. Scalability: These platforms should be able to scale well as they are intended to be used by massive customer bases. They should also manage to withstand demand during peak times and the “flash crowds” phenomenon.

    3. Robustness: The provisioning of the services needs to have continuously high availability by design and redundancy.

    4. Security: Appropriate levels of security need to be provided to protect both the providers and consumers from malicious or fraudulent activities. In fact, without adequate security provisioning it is highly unlikely that any platform will be considered seriously for such scale of business computing.

Peer-to-Peer (P2P) and Grid computing are two very pertinent fields that have received a significant and sustained research interest in terms of designing and deploying large scale and high performance computational resource sharing systems. Computational resources include anything from files and applications to processing cycles and storage space. Effectively these two fields collectively form the de facto basis for the methodologies and techniques that need to be used to develop performance-driven service-oriented software platforms capable of satisfying the aforementioned four key aspects of quality of service.

P2P and Grids started as two different distributed computing philosophies: Grid computing represented a more business-oriented orchestration of relatively homogeneous and powerful distributed computing resources to optimise the execution of time consuming tasks whereas P2P networks had an emphasis on the discovery and sharing of resources on the edges of a heterogeneous network (i.e. user desktops, etc.) especially in terms of file sharing. However, nowadays these two domains have a very substantial overlap as P2P systems have been borrowing on more traditional Grid techniques for task scheduling and execution and the Grid systems have been deploying P2P oriented techniques for more scalable and versatile resource discovery. In fact with the development of very sophisticated information discovery subsystems within Grids, of P2P overlays dedicated to coordinated parallel and distributed processing and of mobile Grids and P2P networks for ad-hoc sharing of mobile telecoms operator services, it has now become more difficult than ever to differentiate these two approaches.

2. Aim & objectives

This handbook aims to address the need for more literature onto the applicability and use of P2P and Grid computing techniques for delivering efficient service-oriented computing. Specifically the book has two key objectives: Firstly to explore how the P2P and Grid paradigms can be used to deliver quality of service in key operations such as the discovery, secure utilisation and coordination of distributed services. Secondly, to use the service-oriented computing as the context of a technical comparison between these two fields. The first objective is closely linked to commercial demand for distributed computing techniques that can form the basis for feasible and efficient solutions for service discovery, secure access and orchestration. The second objective is firmly rooted within the distributed computing academic and research community and its desire to better understand the link between P2P networks and Grids and thus research into potential hybrid solutions.

3. Audience & contribution

The above objectives make this book appropriate and useful to the following audience:

    • researchers and doctoral students working specifically in P2P computing, Grids or SOA implementations and deployments, primarily as a reference publication. Similarly, this book will be useful to researchers in related or more general fields such as distributed computing, software engineering, Web Services, modelling of business processes, etc.

    • academics delivering research-oriented modules in the above fields. This handbook can serve as a good collection of related articles to facilitate a broad understanding of this subject and as such it can become one of the recommended texts in such courses.

    • professional system architects and developers who could decide to adapt and apply in practice a number of the techniques and processes presented in the book.

    • technical managers and IT consultants as a book that demonstrates the potential applicability of certain methods to delivering efficient and secure commercial electronic services to customers globally.

The above categories of readers will find this publication especially appealing as it combines three distinct scholarly contributions:

Firstly it identifies and highlights state-of-the-art techniques and methods from P2P and Grid computing that can be used to build performance-driven service-oriented software platforms. Secondly it uses service-oriented computing as a context to draw a comparison between the P2P and Grid computing paradigms in terms of their ability to provide the necessary quality of service.

Finally, it achieves all of the above through the balanced coverage of both P2P and Grid related research and therefore provides a single reference point for both these technologies. This is academically desirable as the two fields have a significant conceptual overlap and therefore distributed systems researchers are typically interested in knowing about the applicability and usefulness of both P2P and Grids in their research domain. The strong overlapping between them is emphasized by the fact that every major conference, workshop and peer-reviewed journal dedicated on Grid computing typically accepts paper submissions on P2P and vice versa.

4. Handbook Contents This handbook includes 45 high quality fully refereed chapters organised into five sections.

The first section introduces fundamental concepts, techniques and terminology in the fields of service-oriented computing, P2P and Grid computing through a set of literature review articles. This material effectively sets the scene for the remainder of the book. v The following three sections present state-of-the-art research work that contributes towards one of the four quality of service parameters mentioned in the introduction (namely: efficiency, scalability & robustness and security).

The final section concludes the handbook by presenting real applications and lessons learned from using P2P or Grid approaches to realise various aspects of service-oriented computing.

We are certain that you will find each chapter interesting and potentially useful to your work.

The Editors

Nick Antonopoulos
Georgios Exarchakos
Maozhen Li
Antonio Liotta

Author(s)/Editor(s) Biography

Nick Antonopoulos is currently the Head of School of Computing and Assistant Dean (Research) of the Faculty of Business, Computing & law at the University of Derby, UK. Prior to joining Derby he was a Senior Lecturer (US Associate Professor) at the Department of Computing, University of Surrey, UK. He holds a BSc in Physics (1st class) from the University of Athens in1993, an MSc in Information Technology from Aston University in 1994 and a PhD in Computer Science from the University of Surrey in 2000. Before joining the academia he has worked as a networks consultant and was the co-founder and director of a company developing Web-based management information systems. He has over 10 years of academic experience during which he has designed and has been managing advanced Masters programmes in computer science at the University of Surrey. He has published about 70 articles in fully refereed journals and international conferences. He has received a number of best paper awards in conferences and graduated 6 PhD students. He was the organiser and chair of the 1st International Workshop on Computational P2P networks and the 1st International Workshop on Service-Oriented P2P Networks (as part of IEEE Symposium in Cluster Computing and the Grid, CCGrid 2009). He is currently the organiser and chair of the 1st International Conference on Advances in P2P Systems to take place in Malta, October 2009, sponsored by IEEE. He is on the editorial board of the Springer journal of Peer-to-Peer Networking and Applications and on the advisory editorial board of the IGI Global Handbook of Research on Telecommunications Planning and Management for Business. He is a Fellow of the UK Higher Education Academy and a full member of the British Computer Society. His research interests include emerging technologies such as large scale distributed systems and peer-to-peer networks, software agent architectures and security.
George Exarchakos is a Researcher in P2P Computing having completed his PhD in the Department of Computing at the University of Surrey, in 2009. He successfully completed the BSc in Informatics and Telecommunications of the University of Athens in 2004. The same year joined the MSc in Advanced Computing at Imperial College London to complete it in 2005. He collaborated with Network Operation Centre of the University of Athens from 2003 till 2004. His achievements include one best paper award in the International Network Conference 2006 and a best presentation award in the IEEE DEST 2008: International Conference on Digital Ecosystems and Technologies. Since the start of his PhD in 2005 he has contributed to peer-review journals and international conferences with 10 articles. He is involved in the organisation of a number of conferences such as the ComP2P 2008 (First International Workshop on Computational P2P Networks: Theory and Practice), IEEE CCGrid 2009 International Workshop on Service-Oriented P2P Networks and as chair of the program committee of the International Conference on Advances in P2P systems. His teaching experience the last three years includes tutorials, coursework marking and lab support on Software Agents, P2P networks, Artificial Intelligence and Object Oriented Programming modules. His research interests cover the areas of decentralized resource sharing technologies like peer-to-peer networks, cloud computing, cluster computing, software agent platforms and network dynamics modelling.
Maozhen Li is a Lecturer in the School of Engineering and Design at Brunel University, United Kingdom. He received the PhD from Institute of Software, Chinese Academy of Sciences in 1997. He joined Brunel University as a full-time lecturer in 2002. His research interests are in the areas of grid computing, intelligent systems, P2P computing, semantic web, information retrieval, content based image retrieval. He has over 60 scientific publications in these areas. He authored “The Grid: Core Technologies”, a well-recognized textbook on grid computing which was published by Wiley in 2005. He has served as an IPC member for over 30 IEEE conferences. He is on editorial boards of the International Journal of Grid and High Performance Computing, the International Journal of Distributed Systems and Technologies, and the International Journal on Advances in Internet Technology.
Antonio Liotta holds the Chair of Communication Network Protocols at the Eindhoven University of Technology, The Netherlands. He was previously appointed as a Reader at the University of Essex, were he led the Pervasive Services Team, known for its pioneering work on ubiquitous computing, advanced service management, and systems engineering. Antonio is a Fellow of the U.K. Higher Education Academy and serves a number of senior advisory boards including: the Peer Review College of EPSRC (the U.K. Engineering and Physical Sciences Research Council); the scientific advisory panel of the IWT (the Belgian Research Council); the Board of Editors of the Journal of Network and System Management (Springer); and the advisory board of editors of the International Journal of Network Management (Wiley). He is an active member of the networking and network and service management research communities. He has co-organized and co-chaired several international conferences; has served the Technical Programme Committee of over 90 conferences; and has also contributed as keynote and tutorial speaker. Antonio has over 100 publications to his credit, in the areas of telecommunication services, distributed computing, and autonomic networks and systems. Recent articles have contributed to topical themes including: operator-mediated peer-to-peer systems; P2P streaming; quality of experience management; application-aware networks; context-aware adaptive services; and self-configurable networks.