1 **********************************************************************
File and Object Replication in Data Grids. H. Stockinger, A. Samar, B.
Allcock, I. Foster, K. Holtman, and B. Tierney
------------------------------------------------------------------------
Data replication is a key issue in a Data Grid and can be managed in
different ways and at different levels of granularity: for example, at
the file level or object level. In the High Energy Physics community,
Data Grids are being developed to support the distributed analysis of
experimental data. We have produced a prototype data replication tool,
the Grid Data Management Pilot (GDMP) that is in production use in one
physics experiment, with middleware provided by the Globus Toolkit used
for authentication, data movement, and other purposes. We present here a
new, enhanced GDMP architecture and prototype implementation that uses
Globus Data Grid tools for efficient file replication. We also explain
how this architecture can address object replication issues in an
object-oriented database management system. File transfer over wide-area
networks requires specific performance tuning in order to gain optimal
data transfer rates. We present performance results obtained with
GridFTP, an enhanced version of FTP, and discuss tuning parameters.
Présentation Fraga Nacir
2 **********************************************************************
What Makes Workflows Work in an Opportunistic Environment? Ewa Deelman,
Tevfik Kosar, Carl Kesselman and Miron Livny
------------------------------------------------------------------------
In this paper, we examine the issues of workflow mapping and execution
in opportunistic environments such as the grid. As applications become
ever more complex, the process of choosing the appropriate resources and
successfully executing the application components becomes ever more
difficult. In this paper, we focus on the interplay between a workflow
mapping component that plans the high-level resource assignments and the
workflow executor that oversees the component execution. We concentrate
particularly on issues of data management and we draw from the
experiences with mapping and execution systems: Pegasus, DAGMan and Stork.
Présentation Tito Hu
3 **********************************************************************
Grid Services for Distributed System Integration. I. Foster, C.
Kesselman, J. Nick, S. Tuecke
------------------------------------------------------------------------
The Open Grid Services Architecture enables the integration of services
and resources across distributed, heterogeneous, dynamic virtual
organizationsÑwhether within a single enterprise or extending to
external resource-sharing and service-provider relationships.
Présentation Kouni Hajer
4 **********************************************************************
A Dynamic Co-Allocation Service in Multicluster Systems, J.M.P. Sinaga,
H.H. Mohamed, and D.H.J. Epema
------------------------------------------------------------------------
In multicluster systems, and more generally in grids, jobs may require
co-allocation, i.e., the simultaneous allocation of resources such as
processors in multiple clusters to improve their performance. In
previous work, we have studied processor co-allocation through
simulations. Here, we extend this work with the design and
implementation of a dynamic processor co-allocation service in
multicluster systems. While an implementation of basic co-allocation
mechanisms has existed for some years in the form of the DUROC component
of the Globus Toolkit, DUROC does not provide resource-brokering
functionality or fault tolerance in the face of job submission or
completion failures. Our design adds these two elements in the form of a
software layer on top of DUROC. We have performed experiments that show
that our co-allocation service works reliably.
5 **********************************************************************
Mapping Abstract Complex Workflows onto Grid Environments. E. Deelman,
J. Blythe, Y. Gil, C. Kesselman, G. Mehta, K. Vahi, K. Blackburn, A.
Lazzarini, A. Arbree, R. Cavanaugh, S. Koranda.
------------------------------------------------------------------------
In this paper we address the problem of automatically generating job
workflows for the Grid. These workflows describe the execution of a
complex application built from individual application components. In our
work we have developed two workflow generators: the first (the Concrete
Workflow Generator CWG) maps an abstract workflow defined in terms of
application-level components to the set of available Grid resources. The
second generator (Abstract and Concrete Workflow Generator, ACWG) takes
a wider perspective and not only performs the abstract to concrete
mapping but also enables the construction of the abstract workflow based
on the available components. This system operates in the application
domain and chooses application components based on the application
metadata attributes. We describe our current ACWG based on AI planning
technologies and outline how these technologies can play a crucial role
in developing complex application workflows in Grid environments.
Although our work is preliminary, CWG has already been used to map high
energy physics applications onto the Grid. In one particular experiment,
a set of production runs lasted 7 days and resulted in the generation of
167,500 events by 678 jobs. Additionally, ACWG was used to map
gravitational physics workflows, with hundreds of nodes onto the
available resources, resulting in 975 tasks, 1365 data transfers and 975
output files produced.
6 **********************************************************************
RPC-V: Toward Fault-Tolerant RPC for Internet Connected Desktop Grids
with Volatile Nodes , Samir Djilali, Thomas Herault, Oleg Lodygensky,
Tangui Morlier, Gilles Fedak and Franck Cappello
------------------------------------------------------------------------
RPC is one of the programming models envisioned for the Grid. In
Internet connected Large Scale Grids such as Desktop Grids, nodes and
networks failures are not rare events. This paper provides several
contributions, examining the feasibility and limits of fault-tolerant
RPC on these platforms. First, we characterize these Grids from their
fundamental features and demonstrate that their applications scope
should be safely restricted to stateless services. Second, we present a
new fault-tolerant RPC protocol associating an original combination of
three-tier architecture, passive replication and message logging. We
describe RPC-V, an implementation of the proposed protocol within the
XtremWeb Desktop Grid middleware. Third, we evaluate the performance of
RPC-V and the impact of faults on the execution time, using a real life
application on a Desktop Grid testbed assembling nodes in France and
USA. We demonstrate that RPC-V allows the applications to continue their
execution while key system components fail.
Présentation : Poyade Matthieu
7 **********************************************************************
Design, implementation and performance evaluation of GridRPC programming
middleware for a large-scale computational Grid Yoshio Tanaka, Hiroshi
Takemiya, Hidemoto Nakada, Satoshi Sekiguchi
------------------------------------------------------------------------
This paper reports on the design, implementation and performance
evaluation of a suite of GridRPC programming middleware called Ninf-G
Version 2 (Ninf-G2). NinfG2 is a reference implementation of the GridRPC
API, a proposed GGF standard. Ninf-G2 has been designed so that it
provides 1) high performance in a large-scale computational Grid, 2) the
rich functionalities which are required to adapt to compensate for the
heterogeneity and unreliability of a Grid environment, and 3) an API
which supports easy development and execution of Grid applications.
Ninf-G2 is implemented to work with basic Grid services, such as GSI,
GRAM, and MDS in the Globus Toolkit version 2. The performance of
Ninf-G2 was evaluated using a weather forecasting system which was
developed using Ninf-G2. The experimental results indicate that high
performance can be attained even in relatively fine-grained
task-parallel applications on hundreds of processors in a Grid environment.
Présentation : Saraydaryan Jacques
8 **********************************************************************
An Evaluation of the Close-to-Files Processor and Data Co-Allocation
Policy in Multiclusters, H.H. Mohamed and D.H.J. Epema
------------------------------------------------------------------------
In multicluster systems, and more generally, in grids, jobs may require
co-allocation, i.e., the simultaneous allocation of resources such as
processors and input files in multiple clusters. While such jobs may
have reduced runtimes because they have access to more resources,
waiting for processors in multiple clusters and for the input files to
become available in the right locations may introduce inefficiencies. In
previous work, we have studied through simulations only processor
co-allocation. Here, we extend this work with an analysis of the
performance in a real testbed of our prototype Processor and Data
Co-Allocator with the Close-toFiles (CF) job-placement algorithm. CF
tries to place job components on clusters with enough idle processors
which are close to the sites where the input files reside. We present a
comparison of the performance of CF and the Worst-Fit job-placement
algorithm, with and without file replication, achieved with our
prototype. Our most important findings are that CF with replication
works best, and that the utilization in our testbed can be driven to
about 80%.
Présentation : Nguyen Tuan Anh
9 **********************************************************************
Integration of Scheduling and Replication in Data Grids, Anirban
Chakrabarti, Dheepak R.A., Shubhashis Sengupta
------------------------------------------------------------------------
Data Grids seek to harness geographically distributed resources for
large-scale data-intensive problems. Such problems involve loosely
coupled jobs and large data sets distributed remotely. Data Grids have
found applications in scientific research fields of high-energy
physics, life sciences etc. as well as in the enterprises. The issues
that need to be considered in the Data Grid research area include
resource management for computation and data. Computation management
comprises scheduling of jobs, scalability, and response time;
while data management includes replication and movement of data
at selected sites. As jobs are data intensive, data management
issues often become integral to the problems of scheduling and effective
resource management in the Data Grids. The paper deals with the problem
of integrating the scheduling and replication strategies. As part of
the solution, we have proposed an Integrated Replication and Scheduling
Strategy (IRS) which aims at an iterative improvement of the
performance based on coupling between the two scheduling and
replication. Results suggest that, in the context of our experiments,
IRS performs better than several well-known replication strategies.
Présentation Tarek Turki
10 **********************************************************************
Distributed Computing in Practice: The Condor Experience, Douglas Thain,
Todd Tannenbaum, and Miron Livny
------------------------------------------------------------------------
Since 1984, the Condor project has enabled ordinary users to do
extraordinary computing. Today, the project continues to explore the
social and technical problems of cooperative computing on scales ranging
from the desktop to the world-wide computational grid. In this chapter,
we provide the history and philosophy of the Condor project and describe
how it has interacted with other projects and evolved along with the
field of distributed computing. We outline the core components of the
Condor system and describe how the technology of computing must
correspond to social structures. Throughout, we reflect on the lessons
of experience and chart the course traveled by research ideas as they
grow into production systems.
Présentation Pierre Parrend
11 **********************************************************************
A Peer-to-Peer Replica Location Service Based on A Distributed Hash
Table, Min Cai, Ann Chervenak, Martin Frank
------------------------------------------------------------------------
A Replica Location Service (RLS) allows registration and discovery of
data replicas. In earlier work, we proposed an RLS framework and
described the performance and scalability of an RLS implementation in
Globus Toolkit Version 3.0. In this paper, we present a Peer-to-Peer
Replica Location Service (P-RLS) with properties of self-organization,
fault-tolerance and improved scalability. P-RLS uses the Chord
algorithm to self-organize PRLS servers and exploits the Chord overlay
network to replicate P-RLS mappings adaptively. Our performance
measurements demonstrate that update and query latencies increase at a
logarithmic rate with the size of the P-RLS network, while the overhead
of maintaining the P-RLS network is reasonable. Our simulation results
for adaptive replication demonstrate that as the number of replicas per
mapping increases, the mappings are more evenly distributed among
P-RLS nodes. We introduce a predecessor replication scheme and show
it reduces query hotspots of popular mappings by distributing
queries among nodes.
Présentation Zerroug Abdelhalim
12 **********************************************************************
Topologically-Aware Overlay Construction and Server Selection, Sylvia
Ratnasamy, Mark Handley, Richard Karp, Scott Shenker
------------------------------------------------------------------------
A number of large-scale distributed Internet applications could
potentially benefit from some level of knowledge about the relative
proximity between its participating host nodes. For example, the
performance of large overlay networks could be improved if the
application-level connectivity between the nodes in these networks is
congruent with the underlying IP-level topology. Similarly, in the case
of replicated web content, client nodes could use topological
information in selecting one of multiple available servers. For such
applications, one need not find the optimal solution in order to achieve
significant practical benefits. Thus, these applications, and presumably
others like them, do not require exact topological information and can
instead use sufficiently informative hints about the relative positions
of Internet hosts.
In this paper, we present a binning scheme whereby nodes partition
themselves into bins such that nodes that fall within a given bin are
relatively close to one another in terms of network latency. Our binning
strategy is simple (requiring minimal support from any measurement
infrastructure), scalable (requiring no form of global knowledge, each
node only needs knowledge of a small number of well-known landmark
nodes) and completely distributed (requiring no communication or
cooperation between the nodes being binned).
We apply this binning strategy to the two applications mentioned above:
overlay network construction and server selection. We test our binning
strategy and its application using simulation and Internet measurement
traces. Our results indicate that the performance of these applications
can be significantly improved by even the rather coarse-grained
knowledge of topology offered by our binning scheme.
Présentation Dekar Lyes
13 ********************************************************************************
A Note on Distributed Computing
Samuel C. Kendall, Jim Waldo, Ann Wollrath and Geoff Wyant
-------------------------------
TR-94-29 November 1994 Sun http://research.sun.com/techrep/1994/abstract-29.html
We argue that objects that interact in a distributed system need to be dealt
with in ways that are intrinsically different from objects that interact in a
single address space. These differences are required because distributed
systems require that the programmer be aware of latency, have a different
model of memory access, and take into account issues of concurrency and
partial failure.
We look at a number of distributed systems that have attempted to paper over
the distinction between local and remote objects, and show that such systems
fail to support basic requirements of robustness and reliability. These
failures have been masked in the past by the small size of the distributed
systems that have been built. In the enterprise-wide distributed systems
foreseen in the near future, however, such a masking will be impossible.
We conclude by discussing what is required of both systems-level and
application-level programmers and designers if one is to take distribution
seriously.
Présentation Haddad Mohammed
14 ********************************************************************************
Tapestry: A resilient Global-Scale Overlay for Service Deployment
Ben Y. Zhao, Ling Huang, Jeremy Stribling, Sean C. Rhea, Anthony D. Joseph, John D. Kubiatowicz
-----------------------------------------------------------------------------
IEEE Journal on Selected Areas in Communications
Abstract: We present Tapestry, a peer-to-peer overlay routing infrastructure
offering efficient, scalable, location-independent routing of messages
directly to nearby copies of an object or service using only localized
resources. Tapestry supports a generic decentralized object location and
routing applications program- ming interface using a self-repairing,
soft-state-based routing layer. This paper presents the Tapestry architecture,
algorithms, and implementation. It explores the behavior of a Tapestry
deployment on PlanetLab, a global testbed of approximately 100 machines.
Experimental results show that Tapestry exhibits stable behavior and
performance as an overlay, despite the instability of the underlying network
layers. Several widely distributed applications have been implemented on
Tapestry, illustrating its utility as a deployment infrastructure.
Présentation Liu Sen
15 *********************************************************************************
GRIDKIT: Pluggable Overlay Networks for Grid
Grace, P. and Coulson, G. and Blair, G. and Mathy, L. and Yeung, W.K. and Cai,
W and Duce, D. and Cooper, C
---------------------------------------------------------------------------------
Distributed Objects and Applications (DOA 04), Cyprus, Oct .
A second generation approach to the provision of Grid middleware
is now emerging which is built on service-oriented architecture and web
services standards and technologies. However, advanced Grid applications have
significant demands that are not addressed by present-day web services
platforms. As one prime example, current platforms do not support the rich
diversity of communication interaction typest that are demanded by advanced
applications (e.g. publish-subscribe, media streaming, peer-to-peer
interaction).
In the paper we describe the Gridkit middleware which augments the basic
service-oriented architecture to address this particular deficiency. We
particularly focus on the communications infrastructure support required to
support multiple interaction types in a unified, principled and extensible
mannerwhich we present in terms of the novel concept of pluggable
overlay networks.
Présentation Rodrigues de Morais Sergio
16 **********************************************************************************
MJ: A Rational Module System for Java and its Applications
Corwin, D.F. Bacon, D. Grove and C. Murthy
---------------------------------------------------------------------------------
Proceedings of the 18th ACM SIGPLAN Conference on Object-Oriented Programming,
Systems, Language and Applications (OOPLSA)
While Java provides many software engineering benefits, it lacks a
coherent module system and instead provides only packages (which
are primarily a name space mechanism) and classloaders (which
are very low-level). As a result, large Java applications suffer from
unexpected interactions between independent components, require
complex CLASSPATH definitions, and are often extremely com-
plex to install and maintain. We have implemented a module sys-
tem for Java called MJ that is implemented with class loaders, but
provides a much higher-level interface. High-level properties can
be specified in a module definition and are enforced by the mod-
ule system as new modules are loaded. To experimentally validate
the ability of MJ to properly handle the complex module inter-
relationships found in large Java server systems, we replaced the
classloader mechanisms of Apache Tomcat 4.1.18 [27] with 30 MJ
modules. The modified Tomcat is functionally identical to the orig-
inal, but requires no CLASSPATH definitions, and will operate cor-
rectly even if user code loads a different version of a module used
by Tomcat, such as the Xerces XML parser [31]. Furthermore, by
making a small change to the Java core libraries enabled by MJ, we
obtained a 30% performance improvement in a servlet microbench-
mark.
Présentation Sylvain Sené
17 ********************************************************************
Cervantes, H. and Favre, J. M.
Comparing JavaBeans and OSGi Towards an Integration of two Complementary
Component Models
--------------------------------------------------------------------
28th Euromicro Conference on Component Based Software Engineering (ECBSE)
In today's software engineering practices, building
applications from components is the ongoing trend. What
can be noticed however is that there really is not a clear
consensus about the definition of components, and instead
cn the literature we find many definitions of what
components are. This renders a comparison between
component models difficult. However, it is possible to
compare different component models over a list of
characteristics that several authors agree that they should
be found in a component model. In this article, Sun's
javaBeans and the Open Services Gateway Initiative's
ftramework (OSGi) are compared. These are two
technologies that target very different types of
applications. Their study reveals, however, that both
fechnologies cover, at different levels, a set of important
features that characterize components. It also reveals that
chese component models are in some ways
complementary. The paper concludes by giving a
proposal to integrate these two technologies to obtain a
more complete component model.
18 ************************************************************************
Welsh, Matt and Culler, David and Brewer, Eric
SEDA: An architecture for Well-Conditioned Scalable Internet Services
----------------------------------------------------------------------
SOSP-18, Chateau Lake Louise, Canada, October 21-24
We propose a new design for highly concurrent Internet services, which
we call the staged event-driven architecture (SEDA). SEDA is intended
to support massive concurrency demands and simplify the construc-
tion of well-conditioned services. In SEDA, applications consist of a
network of event-driven stages connected by explicit queues. This ar-
chitecture allows services to be well-conditioned to load, preventing
resources from being overcommitted when demand exceeds service ca-
pacity. SEDA makes use of a set of dynamic resource controllers to
keep stages within their operating regime despite large fluctuations in
load. We describe several control mechanisms for automatic tuning
and load conditioning, including thread pool sizing, event batching, and
adaptive load shedding. We present the SEDA design and an implemen-
tation of an Internet services platform based on this architecture. We
evaluate the use of SEDA through two applications: a high-performance
HTTP server and a packet router for the Gnutella peer-to-peer file shar-
ing network. These results show that SEDA applications exhibit higher
performance than traditional service designs, and are robust to huge
variations in load.
Présentation Falquet Nicolas
19 **********************************************************************
Tobin J. Lehman, Alex Cozzi, Yuhong Xiong, Jonathan Gottschalk,
Venu Vasudevan, Sean Landis, Pace Davis, Bruce Khavar, Paul Bowman
Hitting the distributed computing sweet spot with TSpaces
---------------------------------------------------------------------
Computer Networks
Our world is becoming increasingly heterogeneous, decentralized and
distributed, but the software that is supposed
to work in this world, usually, is not. TSpaces is a communication package
whose purpose is to alleviate the problems of
hooking together disparate distributed systems. TSpaces is a global
communication middleware component that incorporates
database features, such as transactions, persistent data, Øexible queries and
XML support. TSpaces is an
excellent tool for building distributed applications, since it provides an
asynchronous and anonymous link between
multiple clients or services. The communication link provided by TSpaces gives
application builders the advantage of
ignoring some of the harder aspects of multi-client synchronization, such as
tracking names (and addresses) of all active
clients, communication line status, and conversation status. For many
different types of applications, the loose synchronization
provided by TSpaces works extremely well. This paper relates our experiences
in building distributed
systems with TSpaces as the central communication component.
Présentation Perevozov Maksym
20 *****************************************************************************
Licia Capra and Wolfgang Emmerich and Cecilia Mascolo
Reflective Middleware Solutions for Context-Aware Applications
----------------------------------------------------------------------------
Lecture Notes in Computer Science 2192
In this paper, we argue that middleware for wired distributed
systems cannot be used in a mobile setting, as the principle of transparency
that has driven their design runs counter to the new degrees of
awareness imposed by mobility. We propose the marriage of re
ection
and metadata as a means for middleware to give applications dynamic
access to information about their execution context. Finally, we describe
a conceptual model that provides the basis of our re
ective middleware.
Présentation Bdira Mezri
21 ******************************************************************************
Alfonso Fuggetta and Gian Pietro Picco and Giovanni Vigna
Understanding Code Mobility
-----------------------------------------------------------------------------
IEEE Transactions on Software Engineering, Vol 24 Num 5
The technologies, architectures, and methodologies traditionally used to
develop distributed applications exhibit a variety of
limitations and drawbacks when applied to large scale distributed settings
(e.g., the Internet). In particular, they fail in providing the
desired degree of configurability, scalability, and customizability. To
address these issues, researchers are investigating a variety of
innovative approaches. The most promising and intriguing ones are those based
on the ability of moving code across the nodes of a
network, exploiting the notion of mobile code. As an emerging research field,
code mobility is generating a growing body of scientific
literature and industrial developments. Nevertheless, the field is still
characterized by the lack of a sound and comprehensive body of
concepts and terms. As a consequence, it is rather difficult to understand,
assess, and compare the existing approaches. In turn, this
limits our ability to fully exploit them in practice, and to further promote
the research work on mobile code. Indeed, a significant symptom
of this situation is the lack of a commonly accepted and sound definition of
the term mobile code itself.
This paper presents a conceptual framework for understanding code mobility.
The framework is centered around a classification
that introduces three dimensions: technologies, design paradigms, and
applications. The contribution of the paper is two-fold. First, it
provides a set of terms and concepts to understand and compare the approaches
based on the notion of mobile code. Second, it
introduces criteria and guidelines that support the developer in the
identification of the classes of applications that can leverage off
of mobile code, in the design of these applications, and, finally, in the
selection of the most appropriate implementation technologies.
The presentation of the classification is intertwined with a review of
state-of-the-art in the field. Finally, the use of the classification is
exemplified in a case study.
Présentation Tran The Tung
22 *****************************************************************************
N. Furmento and W. Lee and A. Mayer and S. Newhouse and J. Darlington
ICENI: An Open Grid Service Architecture Implemented with JINI
------------------------------------------------------------------------------
The move towards Service Grids, where services are composed to
meet the requirements of a user community within constraints specified by the
resource provider, present many challenges to service provision and
description.
To support our research activities in the autonomous composition of services
to
form a Semantic Service Grid we describe the adoption within ICENI of web
services
to enable interoperability with the recently proposed Open Grid Services
Architecture.
Présentation Li Zao
23 ******************************************************************************
Yang Yu, Bhaskar Krishnamachari, and Viktor K
Issues in Designing Middleware for Wireless Sensor Networks
-------------------------------------------------------------------------------
IEEE Network
Wireless sensor networks are being developed for a
variety of applications. With the continuing advances in network
and application design, appropriate middleware is needed to
provide both standardized and portable system abstractions and
the capability to support and coordinate concurrent applications
on sensor networks. In this paper, we first identify several design
principles for such a middleware. These principles motivate a
cluster-based lightweight middleware framework that separates
application semantics from the underlying hardware, operating
system, and network infrastructure. We propose a layered
architecture for each cluster that consists of a cluster control
layer and a resource management layer. Key design issues and
related challenges within this framework that deserve further
investigation are outlined. Finally, we discuss a technique for
energy-efficient resource allocation in a single-hop cluster, which
serves as a basic primitive for the development of the resource
management layer.
Présentation : Guo Yuing
24 ******************************************************************************
W. Heinzelman and A. Murphy and H. Carvalho and M. Perillo
Middleware to support sensor network applications
------------------------------------------------------------------------------
Current trends in computing include increases in both distribution and
wireless connectivity,
leading to highly dynamic, complex environments on top of which applications
must be built. The task of designing and ensuring the correctness of
applications in these environments is similarly becoming more complex. The
unified
goal of much of the research in distributed wireless systems is to provide
higherlevel
abstractions of complex low-level concepts to application programmers, easing
the design and implementation of applications. A new and growing class of
applications for wireless sensor networks require similar complexity
encapsulation.
However, sensor networks have some unique characteristics, including dynamic
availability of data sources and application quality of service requirements,
that
are not common to other types of applications. These unique features, combined
with the inherent distribution of sensors, and limited energy and bandwidth
resources, dictate the need for network functionality and the individual
sensors to
be controlled to best serve the application requirements. In this article we
describe
different types of sensor network applications and discuss existing techniques
for
managing these types of networks. We also overview a variety of related
middleware
and argue that no existing approach provides all the management tools
required by sensor network applications. To meet this need, we have developed
a
new middleware called MiLAN. MiLAN allows applications to specify a policy for
managing the network and sensors, but the actual implementation of this policy
is
effected within MiLAN. We describe MiLAN and show its effectiveness through
the
design of a sensor-based personal health monitor.
Présentaion Doumat Reim
25 *******************************************************************************
R. Guerraoui and A. Schiper
Consensus: the Big Misunderstanding
-------------------------------------------------------------------------------
Proceedings of the 6th {IEEE} Computer Society Workshop on Future Trends in
Distributed Computing Systems ({FTDCS}-6)
The paper aims at clarifying some misunderstandings about the consensus
problem. These misunderstandings prevent consensus from being considered as it
should be, i.e., a fundamental paradigm in the context of fault-tolerant
distributed systems, not only from a theoretical point of view, but also from
a practical point of view. Six frequent misunderstandings are discussed.
Présentation Gravier Christophe