This document discusses efficiency and information management in peer-to-peer systems. It covers trends in peer-to-peer research where quality aspects such as reliability, adaptability, and efficiency are gaining importance as applications become more complex. It also presents approaches for quality of service and emergency call handling in peer-to-peer overlays, as well as a vision for an efficiency management system to optimize resource usage across overlays.
IEEE P2P 2009 - Kalman Graffi - Monitoring and Management of Structured Peer-...Kalman Graffi
The peer-to-peer paradigm shows the potential to provide the same functionality and quality like client/server based systems, but with much lower costs. In order to control the quality of peer-to-peer systems, monitoring and management mechanisms need to be applied. Both tasks are challenging in large-scale networks with autonomous, unreliable nodes. In this paper we present a monitoring and management framework for structured peer-to-peer systems. It captures the live status of a peer-to-peer network in an exhaustive statistical representation. Using principles of autonomic computing, a preset system state is approached through automated system re-configuration in the case that a quality deviation is detected. Evaluation shows that the monitoring is very precise and lightweight and that preset quality goals are reached and kept automatically.
Kalman Graffi - Monitoring and Management of P2P Systems - 2010Kalman Graffi
This is the long presentation of the contributions made in the dissertation of Dr.-Ing. Kalman Graffi - Monitoring and Management of P2P Systems. The talk was given at 29. Sept. 2009 in Madrid / Spain.
Today's Top "RESTful" Services and Why They Are Not RESTfulDominik Renzel
Presentation of WISE 12 Paper "Today's Top "RESTful" Services and Why They Are Not RESTful" (Renzel, Schlebusch, Klamma)
Abstract: Since Fielding's seminal contribution on the REST architecture style in 2000, the so-called class of RESTful services has taken off to challenge previously existing Web services. Several books have since then emerged, providing a set of valuable guidelines and design principles for the development of truly RESTful services. However, today's most popular "RESTful" services adopt only few of these guidelines, resulting in overburdening developers integrating multiple services in mashup applications. In this paper we present an in-depth analysis for the top 20 RESTful services listed on programmableweb.com against 17 RESTful service design criteria found in literature. Results provide evidence that hardly any of the services claiming to be RESTful is truly RESTful, probably due to the lack of rigidness and ease-of-use of currently available decision criteria. To improve the situation, we provide recommendations for various stakeholder groups.
Full Paper: http://www.springerlink.com/index/42307200X642M240.pdf
IEEE P2P 2009 - Kalman Graffi - Monitoring and Management of Structured Peer-...Kalman Graffi
The peer-to-peer paradigm shows the potential to provide the same functionality and quality like client/server based systems, but with much lower costs. In order to control the quality of peer-to-peer systems, monitoring and management mechanisms need to be applied. Both tasks are challenging in large-scale networks with autonomous, unreliable nodes. In this paper we present a monitoring and management framework for structured peer-to-peer systems. It captures the live status of a peer-to-peer network in an exhaustive statistical representation. Using principles of autonomic computing, a preset system state is approached through automated system re-configuration in the case that a quality deviation is detected. Evaluation shows that the monitoring is very precise and lightweight and that preset quality goals are reached and kept automatically.
Kalman Graffi - Monitoring and Management of P2P Systems - 2010Kalman Graffi
This is the long presentation of the contributions made in the dissertation of Dr.-Ing. Kalman Graffi - Monitoring and Management of P2P Systems. The talk was given at 29. Sept. 2009 in Madrid / Spain.
Today's Top "RESTful" Services and Why They Are Not RESTfulDominik Renzel
Presentation of WISE 12 Paper "Today's Top "RESTful" Services and Why They Are Not RESTful" (Renzel, Schlebusch, Klamma)
Abstract: Since Fielding's seminal contribution on the REST architecture style in 2000, the so-called class of RESTful services has taken off to challenge previously existing Web services. Several books have since then emerged, providing a set of valuable guidelines and design principles for the development of truly RESTful services. However, today's most popular "RESTful" services adopt only few of these guidelines, resulting in overburdening developers integrating multiple services in mashup applications. In this paper we present an in-depth analysis for the top 20 RESTful services listed on programmableweb.com against 17 RESTful service design criteria found in literature. Results provide evidence that hardly any of the services claiming to be RESTful is truly RESTful, probably due to the lack of rigidness and ease-of-use of currently available decision criteria. To improve the situation, we provide recommendations for various stakeholder groups.
Full Paper: http://www.springerlink.com/index/42307200X642M240.pdf
Multimedia Processing on Multimedia Semantics and Multimedia ContextRalf Klamma
The 10thWorkshop on Multimedia Metadata (SeMuDaTe‘09)
Yiwei Cao, Ralf Klamma, and Dejan KovachevI
Informatik 5 (Information Systems), RWTH Aachen University
2.12.2009
Graz, Austria
Science meets IT
Wat heeft de Nederlandse wetenschap eigenlijk in de naaste toekomst te bieden op het gebied van duurzaamheid. Discussie met Nederlandse topwetenschappers Prof.ir. Ton Koonen en
Prof. dr. ir. Gerard Smit.
Moderator: Roel Croes (mede-oprichter en bestuurslid Stichting GreenICT)
Prof.ir. Ton Koonen (hoogleraar Technische Universiteit Eindhoven)
Prof. dr. ir. Gerard Smit (hoogleraar Universiteit Twente)
IEEE CCNC 2011: Kalman Graffi - LifeSocial.KOM: A Secure and P2P-based Soluti...Kalman Graffi
The phenomenon of online social networks reaches millions of users in the Internet nowadays. In these, users present themselves, their interests and their social links which they use to interact with other users. We present in this paper LifeSocial.KOM, a p2p-based platform for secure online social networks which provides the functionality of common online social networks in a totally distributed and secure manner. It is plugin-based, thus extendible in its functionality, providing secure communication and access-controlled storage as well as monitored quality of service, addressing the needs of both, users and system providers. The platform operates solely on the resources of the users, eliminating the concentration of crucial operational costs for one provider. In a testbed evaluation, we show the feasibility of the approach and point out the potential of the p2p paradigm in the field of online social networks.
Building a Maturity & Capability Model RepositoryLuigi Buglione
This presentation shows the MCM (Maturity & Capability Models) repository initiative, discussing the opportunity from the LEGO approach in your organization
Research Overview about the Multimedia Communications Lab (KOM) - Technische Universität Darmstadt - Germany
Research areas towards Adaptive Seamless Multimedia Communications are: Knowledge & Educational Technologies, Multimedia Technologies & Serious Games, Mobile Systems & Sensor Networks, Self-organizing Systems & Overlay Communications, Service-oriented Computing
Estimation represents one of the most critical processes for any project and it is highly dependent on the quality of requirements elicitation and management. Therefore, the management of requirements should be prioritised in any process improvement program, because the less precise the requirements gathering, analysis and sizing, the greater the error in terms of time and cost estimation. Maturity and Capability Models (MCM) represent a good tool for assessing the status of a set of processes, but an inner limit of any model is its scope and approach for describing a certain issue. Thus, integrating two or more models with a common area of focus can offer more information and value for an organization, keeping the best components from each model. LEGO (Living EnGineering prOcess) is an approach projected for this purpose. This paper proposes a LEGO application hybridizing a ‘horizontal’ model (a MM containing processes going through the complete supply chain, from requirements right through to delivery, e.g. CMMI or ISO 12207/15504) with a few specific ‘vertical’ models (MMs with focus on a single perspective or process category, e.g. TMMi or TPI in the Test Management domain, P3M3 and OPM3 in the Project Management domain) for Requirement Engineering.
Multimedia Processing on Multimedia Semantics and Multimedia ContextRalf Klamma
The 10thWorkshop on Multimedia Metadata (SeMuDaTe‘09)
Yiwei Cao, Ralf Klamma, and Dejan KovachevI
Informatik 5 (Information Systems), RWTH Aachen University
2.12.2009
Graz, Austria
Science meets IT
Wat heeft de Nederlandse wetenschap eigenlijk in de naaste toekomst te bieden op het gebied van duurzaamheid. Discussie met Nederlandse topwetenschappers Prof.ir. Ton Koonen en
Prof. dr. ir. Gerard Smit.
Moderator: Roel Croes (mede-oprichter en bestuurslid Stichting GreenICT)
Prof.ir. Ton Koonen (hoogleraar Technische Universiteit Eindhoven)
Prof. dr. ir. Gerard Smit (hoogleraar Universiteit Twente)
IEEE CCNC 2011: Kalman Graffi - LifeSocial.KOM: A Secure and P2P-based Soluti...Kalman Graffi
The phenomenon of online social networks reaches millions of users in the Internet nowadays. In these, users present themselves, their interests and their social links which they use to interact with other users. We present in this paper LifeSocial.KOM, a p2p-based platform for secure online social networks which provides the functionality of common online social networks in a totally distributed and secure manner. It is plugin-based, thus extendible in its functionality, providing secure communication and access-controlled storage as well as monitored quality of service, addressing the needs of both, users and system providers. The platform operates solely on the resources of the users, eliminating the concentration of crucial operational costs for one provider. In a testbed evaluation, we show the feasibility of the approach and point out the potential of the p2p paradigm in the field of online social networks.
Building a Maturity & Capability Model RepositoryLuigi Buglione
This presentation shows the MCM (Maturity & Capability Models) repository initiative, discussing the opportunity from the LEGO approach in your organization
Research Overview about the Multimedia Communications Lab (KOM) - Technische Universität Darmstadt - Germany
Research areas towards Adaptive Seamless Multimedia Communications are: Knowledge & Educational Technologies, Multimedia Technologies & Serious Games, Mobile Systems & Sensor Networks, Self-organizing Systems & Overlay Communications, Service-oriented Computing
Estimation represents one of the most critical processes for any project and it is highly dependent on the quality of requirements elicitation and management. Therefore, the management of requirements should be prioritised in any process improvement program, because the less precise the requirements gathering, analysis and sizing, the greater the error in terms of time and cost estimation. Maturity and Capability Models (MCM) represent a good tool for assessing the status of a set of processes, but an inner limit of any model is its scope and approach for describing a certain issue. Thus, integrating two or more models with a common area of focus can offer more information and value for an organization, keeping the best components from each model. LEGO (Living EnGineering prOcess) is an approach projected for this purpose. This paper proposes a LEGO application hybridizing a ‘horizontal’ model (a MM containing processes going through the complete supply chain, from requirements right through to delivery, e.g. CMMI or ISO 12207/15504) with a few specific ‘vertical’ models (MMs with focus on a single perspective or process category, e.g. TMMi or TPI in the Test Management domain, P3M3 and OPM3 in the Project Management domain) for Requirement Engineering.
Dynamic Semantics for the Internet of Things PayamBarnaghi
Ontology Summit 2015 : Track A Session - Ontology Integration in the Internet of Things - Thu 2015-02-05,
http://ontolog-02.cim3.net/wiki/ConferenceCall_2015_02_05
Enhancing Academic Event Participation with Context-aware and Social Recommen...Dejan Kovachev
The plethora of talks and presentations taking place at academic conferences makes it difficult, especially for young researchers to attend the
right talks or discuss with participants and potential collaborators with similar interests. Participants may not have a priori knowledge that allows
them to select the right talks or informal interactions with other participants. In this paper we present the context-aware mobile
recommendation services (CAMRS) based on the current context (whereabouts at the venue, popularity and activities of talks and presentations)
sensed at the conference venue. Additionally, we augment the current context with the academic community context of conference participants
which is inferred by using social network analysis and link prediction on large-scale co-authorship and citation networks of participants. By
combining the dynamic and social context of participants, we are able to recommend talks and people that may be interesting to a particular
participant. We evaluated CAMRS using data from two large digital libraries - the DBLP and CiteSeerX, and participants from two conferences -
ICWL 2010 and EC-TEL 2011. The result shows that the new approach can recommend novel talks and helps participants in establishing new
connections at conference venue.
The LEGO Maturity & Capability Model ApproachLuigi Buglione
“Maturity model” (MM) (based on Crosby’s original idea) has been one of the main buzzwords over the past 20 years. A variety of MMs have been created in several application domains, from Software Engineering to Contract Management. Despite several models intending to cover the same domain, their PRMs (Process Reference Models) typically have different scopes, do not always cover the same set of processes, or have different levels of depth, or do not express the same level of granularity when describing concepts. Thus some important questions from the MM users’ viewpoint arise: how to choose the right models for our needs? After selecting those models, how to build a new, tailored MM based on several sources and customized to a specific domain? This paper motivates these important questions and proposes a way to choose, combine and adapt the contents from multiple MMs within a generic-domain approach we call ‘LEGO’ (Living EnGineering prOcess), based upon the well-known kids’ toy that stimulates creativity through combining different bricks. We present three case studies, one of them based upon the development of the Medi SPICE model, illustrating how the proposed approach may be used to develop MCM (Maturity & Capabilty Models) in this context.
FAIR Computational Workflows
Computational workflows capture precise descriptions of the steps and data dependencies needed to carry out computational data pipelines, analysis and simulations in many areas of Science, including the Life Sciences. The use of computational workflows to manage these multi-step computational processes has accelerated in the past few years driven by the need for scalable data processing, the exchange of processing know-how, and the desire for more reproducible (or at least transparent) and quality assured processing methods. The SARS-CoV-2 pandemic has significantly highlighted the value of workflows.
This increased interest in workflows has been matched by the number of workflow management systems available to scientists (Galaxy, Snakemake, Nextflow and 270+ more) and the number of workflow services like registries and monitors. There is also recognition that workflows are first class, publishable Research Objects just as data are. They deserve their own FAIR (Findable, Accessible, Interoperable, Reusable) principles and services that cater for their dual roles as explicit method description and software method execution [1]. To promote long-term usability and uptake by the scientific community, workflows (as well as the tools that integrate them) should become FAIR+R(eproducible), and citable so that author’s credit is attributed fairly and accurately.
The work on improving the FAIRness of workflows has already started and a whole ecosystem of tools, guidelines and best practices has been under development to reduce the time needed to adapt, reuse and extend existing scientific workflows. An example is the EOSC-Life Cluster of 13 European Biomedical Research Infrastructures which is developing a FAIR Workflow Collaboratory based on the ELIXIR Research Infrastructure for Life Science Data Tools ecosystem. While there are many tools for addressing different aspects of FAIR workflows, many challenges remain for describing, annotating, and exposing scientific workflows so that they can be found, understood and reused by other scientists.
This keynote will explore the FAIR principles for computational workflows in the Life Science using the EOSC-Life Workflow Collaboratory as an example.
[1] Carole Goble, Sarah Cohen-Boulakia, Stian Soiland-Reyes,Daniel Garijo, Yolanda Gil, Michael R. Crusoe, Kristian Peters, and Daniel Schober FAIR Computational Workflows Data Intelligence 2020 2:1-2, 108-121 https://doi.org/10.1162/dint_a_00033.
The LTCI* is a laboratory of Télécom ParisTech (Institut Mines-Télécom, IMT). Established in 1982, LTCI is characterized by its broad coverage of the field of information and communication science and technology (ICT). Its research activities range from the hardware layer (electronics, opto-electronics, system on chip, antennae, microwaves…) to the software layer (systems, algorithms, protocols…). They encompass studies on different kinds of data (audio, video, images, semi-structured data and web content) as well as works on network performance and services, or quantum cryptography issues.
IEEE CRS 2014 - Secure Distributed Data Structures for Peer-to-Peer-based Soc...Kalman Graffi
Jens Janiuk, Alexander Mäcker, Kalman Graffi -
Secure Distributed Data Structures for Peer-to-Peer-based Social Networks
In IEEE CTS ’14: Proceedings of the IEEE International Conference on Collaboration Technologies and Systems, 2014.
Abstract—Online social networks are attracting billions of nowadays, both on a global scale as well as in social enter- prise networks. Using distributed hash tables and peer-to-peer technology allows online social networks to be operated securely and efficiently only by using the resources of the user devices, thus alleviating censorship or data misuse by a single network operator. In this paper, we address the challenges that arise in implementing reliably and conveniently to use distributed data structures, such as lists or sets, in such a distributed hash-table- based online social network. We present a secure, distributed list data structure that manages the list entries in several buckets in the distributed hash table. The list entries are authenticated, integrity is maintained and access control for single users and also groups is integrated. The approach for secure distributed lists is also applied for prefix trees and sets, and implemented and evaluated in a peer-to-peer framework for social networks. Evaluation shows that the distributed data structure is convenient and efficient to use and that the requirements on security hold.
LibreSocial - P2P Framework for Social Networks - OverviewKalman Graffi
Digital social networks promise to activate the social participants and to support them in their interactivity patterns. Private relationships evolve to friendships, professional contacts define competence networks and political opinions emerge to revolutionary trends. Social networks often act as driving force to intensify the social and global relationships.
In future, using the „Peer-to-Peer Framework for Social Networks“ everybody may host easily and out-of-the-box his personal online social network, without operating costs and without security risks. The framework offers a large set of interactive apps, which can be are freely combinable and technically limitless in their applicability.
The operating costs for such a social network are a revolutionary: no expenses arise. Whether a network for 10 users or for a global network of Millions of users, one aspect is common: due to the peer-to-peer technology used, no expenses arise. Researchers led by Dr.-Ing. Kalman Graffi at the University of Paderborn combined in the framework the advantages of decentralized peer-to-peer applications, of an app market as well as the cloud principle.
The social network is maintained in a peer-to-peer fashion through the computational power of the users’ devices, expensive servers are not needed. Still the availability, retrievability and security of the users‘ data are guaranteed. Each user keeps total control on the access control rights of his data. Similar to the main property of the cloud, the network’s capabilities grow elastically with the number of users. Further plugins can be developed easily. An app market that is included allows to provide these plugins in order to extend the capabilities and applications in the social network on the fly.
Enormous application opportunities without operating costs are the main reason to use the „P2P Framework for Social Networks“ emphasize the researchers of the corresponding project group at the University of Paderborn. The software as a prototype is already in use. Contact us for more information.
Timo Klerx and Kalman Graffi. Bootstrapping Skynet: Calibration and Autonomic Self-Control of Structured Peer-to-Peer Networks. In IEEE P2P ’13: Proceedings of the International Conference on Peer-to-Peer Computing, 2013.
Abstract—Peer-to-peer systems scale to millions of nodes and provide routing and storage functions with best effort quality. In order to provide a guaranteed quality of the overlay functions, even under strong dynamics in the network with regard to peer capacities, online participation and usage patterns, we propose to calibrate the peer-to-peer overlay and to autonomously learn which qualities can be reached. For that, we simulate the peer- to-peer overlay systematically under a wide range of parameter configurations and use neural networks to learn the effects of the configurations on the quality metrics. Thus, by choosing a specific quality setting by the overlay operator, the network can tune itself to the learned parameter configurations that lead to the desired quality. Evaluation shows that the presented self-calibration succeeds in learning the configuration-quality interdependencies and that peer-to-peer systems can learn and adapt their behavior according to desired quality goals.
Vitaliy Rapp and Kalman Graffi. Continuous Gossip-based Aggregation through Dynamic Information Aging. In IEEE ICCCN ’13: Proceedings of the International Conference on Computer Communications and Networks, 2013.
Abstract—Existing solutions for gossip-based aggregation in peer-to-peer networks use epochs to calculate a global estimation from an initial static set of local values. Once the estimation converges system-wide, a new epoch is started with fresh initial values. Long epochs result in precise estimations based on old measurements and short epochs result in imprecise aggregated estimations. In contrast to this approach, we present in this paper a continuous, epoch-less approach which considers fresh local values in every round of the gossip-based aggregation. By using an approach for dynamic information aging, inaccurate values and values from left peers fade from the aggregation memory. Evaluation shows that the presented approach for continuous information aggregation in peer-to-peer systems monitors the system performance precisely, adapts to changes and is lightweight to operate.
IEEE ICC 2013 - Symbiotic Coupling of P2P and Cloud Systems: The Wikipedia CaseKalman Graffi
Lars Bremer and Kalman Graffi. Symbiotic Coupling of P2P and Cloud Systems: The Wikipedia Case. In IEEE ICC ’13: Proceedings of the International Conference on Communications, 2013.
Abstract—Comparative evaluations of peer-to-peer protocols through simulations are a viable approach to judge the per- formance and costs of the individual protocols in large-scale networks. In order to support this work, we enhanced the peer- to-peer systems simulator PeerfactSim.KOM with a fine-grained analyzer concept, with exhaustive automated measurements and gnuplot generators as well as a coordination control to evaluate a set of experiment setups in parallel. Thus, by configuring all experiments and protocols only once and starting the simulator, all desired measurements are performed, analyzed, evaluated and combined, resulting in a holistic environment for the comparative evaluation of peer-to-peer systems.
Abstract—Cloud computing offers high availability, dynamic scalability, and elasticity requiring only very little administration. However, this service comes with financial costs. Peer-to-peer systems, in contrast, operate at very low costs but cannot match the quality of service of the cloud. This paper focuses on the case study of Wikipedia and presents an approach to reduce the operational costs of hosting similar websites in the cloud by using a practical peer-to-peer approach. The visitors of the site are joining a Chord overlay, which acts as first cache for article lookups. Simulation results show, that up to 72% of the article lookups in Wikipedia could be answered by other visitors instead of using the cloud.
IEEE HPCS 2013 - Comparative Evaluation of Peer-to-Peer Systems Using Peerfac...Kalman Graffi
Matthias Feldotto and Kalman Graffi. Comparative Evaluation of Peer-to-Peer Systems Using PeerfactSim.KOM. In IEEE HPCS’13: Proceedings of the International Conference on High Per- formance Computing and Simulation, 2013.
IEEE ISM 2008: Kalman Graffi: A Distributed Platform for Multimedia CommunitiesKalman Graffi
Online community platforms and multimedia content delivery are merging in recent years. Current platforms like Facebook and YouTube are client-server based which result in high administration costs for the provider. In contrast to that peer-to-peer systems offer scalability and low costs, but are limited in their functionality. In this paper we present a framework for peer-to-peer based multimedia online communities.We identified the key challenges for this new application of the peer-to-peer paradigm and built a plugin based, easily extendible and multifunctional framework. Further, we identified distributed linked lists as valuable data structure to implement the user profiles, friend lists, groups, photo albums and more. Our framework aims at providing the functionality of common online community platforms combined with the multimedia delivery capabilities of modern peer-to-peer systems, e.g. direct multimedia delivery and access to a distributed multimedia pool.
IEEE ICPADS 2008 - Kalman Graffi - SkyEye.KOM: An Information Management Over...Kalman Graffi
In order to ease the development and maintenance of more complex P2P applications, which combine multiple P2P functionality (e.g. streaming and dependable storage), we suggest to extend structured P2P systems with a dedicated information management layer. This layer is meant to generate statistics on the whole P2P system and to enable capacity-based peer search, which helps the individual functionality layers in the P2P application to find suitable peers for layer-specific role assignment. We present in this paper SkyEye.KOM, an information management layer applicable on DHTs, which fulfills these desired functionality. SkyEye.KOM builds an over-overlay, which is scalable by leveraging the underlying DHT, easy to deploy as simple add-on to existing DHTs and efficient as it needs O(log N) hops per query and to place peer-specific information network wide accessible. Evaluation shows that SkyEye.KOM has a good query performance and that the costs for maintaining the over-overlay are very low.
2. Overview
1 The Peer-to-Peer Paradigm
1.1 Trends in Peer-to-Peer Research
1.2 Quality in Peer-to-Peer Systems
1.3 Serious Future Peer-to-Peer Applications
2 Towards QoS & Emergency Call Handling
2.1 Serious Application: Emergency Call Handling
2.2 Our Approach for P2P-based Emergency Call Handling H(„my data“)
= 3107
1622
1008 2011
709 2207
2.3 Quality of Service for Overlay Traffic 611 2906
3485
3 Lessons Learned for QoS in P2P Systems
4 Towards a Kind of „Efficiency Management”
12.5.7.31
peer-to-peer.info
berkeley.edu planet-lab.org 61.51.166.150
95.7.6.10
86.8.10.18 7.31.10.25
4.1 Current State of Efficiency Management
4.2 Our Vision of an Efficiency Management Lifecycle
4.3 Over-Overlay: Efficiency Management System
4.4 Queries in the Efficiency Management System
4.5 Example Application: Replication Layer
5 Lessons Learned for Efficiency Management in P2P Systems
KOM – Multimedia Communications Lab 2
4. 1 The Peer-to-Peer Paradigm
Peer-to-Peer Systems:
Users of a system provide the infrastructure of the system
Service is provided from users/peers to users/peers
Peer-to-Peer overlays:
virtual networks, providing new functionality H(„my
data“)
= 3107 1008 1622 2011
709 2207
E.g. Distributed Hash Tables, Keyword-based Search 611
3485 2906
12.5.7.31
planet-lab.org peer-to-peer.info
berkeley.edu 61.51.166.150
95.7.6.10
86.8.10.18 7.31.10.25
Evolution of applications
File sharing:
No Quality of Service (QoS) requirements
Voice over IP
Real-time requirements
Video-on-demand
Real-time and bandwidth requirements
KOM – Multimedia Communications Lab 4
5. 1.1 Trends in Peer-to-Peer Research
Quality aspects gain importance
Quality of P2P Systems
Reliability: expected professionalism
Ease of Use:
Adaptability Efficiency Validity Trust
Multimedia and interactivity
Scalability Performance Retrievability Dependability
Stability Service Coherence Availability
Provisioning
Critical success factor for Flexibility
Overlay
Consistency Reliability
complex P2P applications Operations Robustness/
Correctness Fault tolerance
modular P2P applications Costs Security
Individual Node Integrity
Complete System Confidentiality
Quality aspects: IP Infrastructure
Authentication
Non- repudiation
Adaptability – to scenario, system scale
Validity – of stored data
Trust – of users and mechanisms
Efficiency – ratio between performance and costs
KOM – Multimedia Communications Lab 5
6. 1.2 Quality in Peer-to-Peer Systems
DFG Research Group FOR 733 @ TU Darmstadt
QuaP2P
“Verbesserung der Qualität von Peer-to-Peer-Systemen durch die
systematische Erforschung von Qualitätsmerkmalen und deren wechselseitigen
Abhängigkeiten“
User
Online-time Behavior
Approach Model
Evaluation using simulation and Application Layer
Simulation Engine
prototypes Distribution
Strategy
Replication
Strategy
PeerfactSim.KOM
Overlay Layer
Proof-of-Concept of investigated Kademlia Chord
mechanisms using 2 scenarios
Please visit Network Wrapper
www.quap2p.tu-darmstadt.de or www.quap2p.de TCP
UDP
www.peerfactsim.com Package
Loss
Delay
Model
Bandwidth
KOM – Multimedia Communications Lab 6
Visit PeerfactSim.KOM at CeBIT 2008, hall 9, stand C22
7. 1.3 Serious Future Peer-to-Peer Applications
Future Peer-to-Peer based applications
Modular, component based composition
E.g. FreePastry and/with PAST, Scribe,
E.g. POST, SplitStream
A module has to
be highly efficient
provide Quality of Service
Application Areas
To exploit self-organization abilities of P2P
Catastrophe scenarios
require robust mechanisms
E.g. coping with churn
Example: Emergency Call Handling
Hard QoS requirements
Peer-to-peer mechanisms provide failure-tolerance (and QoS)
KOM – Multimedia Communications Lab 7
8. 2 Towards QoS & Emergency Call Handling
QoS Provisioning
Emergency Call Handling
Connect me to an
emergency
station!
KOM – Multimedia Communications Lab 8
9. 2.1 Serious Application: Emergency Call Handling
Emergency Call Handling is not supported in VoIP (Skype)
2009: mandatory for VoIP providers
P2P fits: all-IP, scalable,
but Quality of Service?
Requirements
1. Location critical service:
Find closest/responsible Emergency Station
2. Quality of Service for P2P flows needed
QoS policy: low delay, low loss
contact Emergency Station as soon as possible
without message loss
Goal:
How to solve problem locally ? OR Source: NENA
Source: US census
do we need system wide management? Alabama Emergency Zones
Population density in Alabama
KOM – Multimedia Communications Lab 9
Paper at: K. Graffi et al., “ECHoP2P…”, Int. Workshop on P2P-NVE, Nov. 2007 Snapshot of the simulated scenarios
10. 2.2 Our Approach for P2P-based Emergency Call Handling
Challenge 1: Location-based search requirements
Approach: Globase.KOM - Geographical LOcation BAsed SEarch
Engineered for requirements of location based services
A logical neighbor is a geographical neighbor (like in CAN)
Tree structure enables search/lookup in O(log N)
Extended with following search mechanisms:
Closest peer (Emergency Station)
Peer fulfilling a specific criteria (responsibility)
A B
B C D E F G
J H
F G H I K J Search K E C I
Query
D A
KOM – Multimedia Communications Lab 10
Paper at: A. Kovacevic et al., “Location Awareness…”, Special Issue of the Proc. of the IEEE on Adv. In Distr. Multim. Comm., Jan. 2008
11. 2.3 Quality of Service for Overlay Traffic
Challenge 2: Providing Quality of Service for Overlay Traffic
Approach: Scheduling and Active Queue Management (AQM)
Scheduling: Reordering of packets
AQM: to decide which message to drop at congestion
1. Message Scheduling 2. Queue Management
Before: Before:
After: After:
Queue Limit
Observation:
Classical flows do not exist in P2P overlays Resource
Many small bursts, rarely from the same peers Scheduling &
Requires a stateless solution Queue Mgmt.
Existing solutions mainly focus on classical flows
Need for approaches for Peer-to-Peer systems
KOM – Multimedia Communications Lab 11
See: K. Graffi et al., “Taxonomy on Scheduling/AQM Strategies…” Technical Report, KOM-TR-2007-1,2, TU Darmstadt
12. Overlay Bandwidth Management
Novel substrate “Network Wrapper”
Between overlay and transport layer:
Queues messages
Applies Scheduling and AQM solution: HiPNOS.KOM
HiPNOS.KOM: Highest Priority First, No Starvation
Introduce message priorities for Loss and Delay
AQM: at congestion, drop message with lowest loss-prio.
Scheduling: at free bandwidth, send message with highest delay-prio.
Avoid starvation: Periodically increase delay-prio. of queued messages
Properties of HiPNOS.KOM
Focus on QoS for overlay flows
Easy to apply on existing overlays
KOM – Multimedia Communications Lab 12
Paper at: K. Graffi et al., “Overlay Bandwidth Management …” in Proc. of IEEE Local Computer Networks, Oct. 2007
13. Overlay Bandwidth Management Results
Observation:
Proportional
relations:
Delay
to
delay-priority
KOM – Multimedia Communications Lab 13
Paper at: K. Graffi et al., “Overlay Bandwidth Management …” in Proc. of IEEE Local Computer Networks, Oct. 2007
14. Overlay Bandwidth Management Results
Observation:
Proportional
relations:
Loss
to
loss-priority
KOM – Multimedia Communications Lab 14
Paper at: K. Graffi et al., “Overlay Bandwidth Management …” in Proc. of IEEE Local Computer Networks, Oct. 2007
15. Overlay Bandwidth Management Results
Observation:
Proportional relations:
Delay to delay-priority
Loss to loss-priority
Results:
HiPNOS.KOM provides QoS
Regarding delay and loss
According to chosen priorities
KOM – Multimedia Communications Lab 15
Paper at: K. Graffi et al., “Overlay Bandwidth Management …” in Proc. of IEEE Local Computer Networks, Oct. 2007
16. 3 Lessons Learned for QoS in P2P Systems
Results for Scheduling and AQM
Delay and delay-priority, loss and loss-priority are proportional
Emergency Calls have always highest priority
All other messages have lower priority
Quality of service can be provided
Lessons learned:
IF … known:
Optimization criteria
Set of all alternatives
THEN mechanisms for Quality of Service are easy to adopt
Required Information
Necessary for efficient decisions in distributed systems
Often missing in Peer-to-Peer systems
KOM – Multimedia Communications Lab 16
17. 4 Towards a Kind of „Efficiency Management”
Peers Architecture
Parameters
α
Efficiency λ β
Management μ
Architecture
Using Info. Analysis,
to Gain Modeling and
Efficiency Interpretation
f(α, β)=…=x
g(λ, μ)=…=y
h(α, λ)=…=z
Choose Interpreted Models
priorities state
KOM – Multimedia Communications Lab 17
18. 4.1 Current State of Efficiency Management
Each functional layer
has its own information/analysis architecture
To gather, analyze layer specific information
Examples PAST
BitTorrent: for Tit-for-tat peer selection
Replication: which data, on which peers
Skype: for Superpeer selection
Network wrapper: underlay awareness
Common basic functionality can be “abstracted”,
i.e. “extracted”
To gather layer specific information
To analyze information, (derive optimization goals)
To apply results for better decisions
Separate Information/Efficiency Management Layer for this task
KOM – Multimedia Communications Lab 18
19. 4.2 Our Vision of an Efficiency Management Lifecycle
Efficiency Management System:
Peers Architecture
To engineer & to build architecture
Parameters
To gather information from peers α
To retrieve system parameters Efficiency λ β
Management μ
To analyze component Architecture
To use system model
To prepare statistics
Using Info. Analysis,
To interpret system state to Gain Modeling and
With application Component Efficiency Interpretation
To Provide QoS
Based on f(α, β)=…=x
g(λ, μ)=…=y
above issues h(α, λ)=…=z
Interpreted Models
Choose state
priorities KOM – Multimedia Communications Lab 19
20. 4.3 Over-Overlay: Efficiency Management System
For all structured P2P overlays
Covered by common API
Usable by all functional layers in a P2P system
Enables query for: Efficiency
Management
M peers with System ID
specific characteristics Space
Common API for structured overlays
Application Examples:
Super-peer choosing Structured
3 peer Overlay: DHT
Storage space > 20Mb 12.5.7.31
Bandwidth > 100kb/s
peerto-peer.info
-
Underlay: berkeley.edu planetlab.org
- 89.11.20.15
95.7.6.10
The Internet
86.8.10.18 7.31.10.25
KOM – Multimedia Communications Lab 20
21. Efficiency Management Architecture
Efficiency Management Architecture
Built on underlying structured overlay
Communicates via common API
Route to PeerID ID
Space
Just an add-on, easy to deploy
Common API for structured overlays
Principle
Each node publishes information updates in the architecture
Update-tree is established
Each node knows where to send updates to
Queries are processed bottom up
KOM – Multimedia Communications Lab 21
See: K. Graffi et al., “Towards an Information and Efficiency Management Architecture…” Technical Report, KOM-TR-2008-2, TU Darmstadt
22. Efficiency Management Architecture Details
Over-overlay:
ID space separated in intervals (domains)
Peer responsible for a specific ID (e.g. middle) is responsible for ID domain
Peers in the domain send updates to this Coordinator
Updates propagated upwards the tree
Coordinator Supporting
Peer
Supporting Peers for Load Balancing
Coordinator may chose Supporting Peers
Good peers chosen by 50/50 ratio ID
Space
Pick e.g. 20 best peers in the domain
Best 10 peers in domain advertised one level up Peers
Second best 10 peers can be used as support
Workload can be delegated to supporting peers
Tree depth / peer load adjustable
KOM – Multimedia Communications Lab 22
23. 4.4 Queries in the Efficiency Management System
Query Type:
Give me M peers
Fulfilling specific requirements on
Bandwidth, storage space, computational capabilities,
Online time, peer load, reputation
… (wide set of requirements definable)
Query processing
First sent to coordinator of lowest domain
Query traverses bottom-up, until M matching peers found
Result is sent then to requesting peer
Tradeoff:
Upper peers in tree know more
Load should be kept on lower levels of the tree
KOM – Multimedia Communications Lab 23
24. Structure of the Efficiency Management Arch.
Query Performance: O(log N) hops
Scalability:
Tree-structure of coordinators form information architecture
Supporting peers: Strong peers can take the load
Robustness:
No additional maintenance needed (done by structured overlay)
Any peer can fail, no unwanted effects
KOM – Multimedia Communications Lab 24
25. 4.5 Example Application: Replication Layer
Content storage in P2P systems
Churn is a problem
Data may get lost
Replication is a solution
Challenges
Which files to replicate?
Most requested, rarest?
At which peers?
Most reliable? Highest bandwidth?
How many replicas?
Depends on requirements on availability
By which peers?
Efficiency Management System allows for answers
KOM – Multimedia Communications Lab 25
26. Lessons Learned for Efficiency Management in P2P
5
Systems
Information Management is just
ONE part of the Efficiency Management Lifecycle
Next steps:
To build information analyzing quorum
To process and analyze gathered system parameters
Status determination and prediction
QoS policy determination based on identified QoS requirements
Long-term vision:
P2P network regulates itself
According to QoS constraints towards efficiency
From self-organization of the peers to self-consciousness of the system
Upcoming Applications:
P2P-based Grid: Share resources, negotiate service in return with the system
Modularized, layer-interactive, complex applications
KOM – Multimedia Communications Lab 26
27. Fragen ? – Any Questions ?
Mitglied des Technologiebeirats
Beauftragter für Informations- und
Kommunikationstechnik
des Landes Hessen
KOM – Multimedia Communications Lab 27