9,807 research outputs found
A scalable reliable instant messenger using the SD Erlang libraries
Erlang has world leading reliability capabilities, but while it scales
extremely well within a single node, distributed Erlang has some
scalability issues. The Scalable Distributed (SD) Erlang libraries
have been designed to address the scalability limitations while
preserving the reliability model, and shown to deliver significant
performance benefits above 40 hosts using some relatively simple
benchmarks.
This paper compares the reliability and scalability of SD Erlang
and distributed Erlang using an Instant Messaging (IM) server
benchmark that is a far more typical Erlang application; a relatively
large and sophisticated benchmark; has throughput as the key
performance metric; and uses non-trivial reliability mechanisms.
We provide a careful reliability evaluation using chaos monkey.
The key performance results consider scenarios with and without
failures on up to 17 server hosts (272 cores). We show that SD
Erlang adds no performance overhead when all nodes are grouped in
a single s_group. However, either adding redundant router nodes in
distributed Erlang applications, or dividing a set of nodes into small
s_groups in SD Erlang applications, have small negative impact.
Both the distributed Erlang and SD Erlang IM tolerate failures and,
up to the failure rates measured, the failures have no impact on
throughput. The IM implementations show that SD Erlang preserves
the distributed Erlang reliability properties and mechanisms
Network layer access control for context-aware IPv6 applications
As part of the Lancaster GUIDE II project, we have developed a novel wireless access point protocol designed to support the development of next generation mobile context-aware applications in our local environs. Once deployed, this architecture will allow ordinary citizens secure, accountable and convenient access to a set of tailored applications including location, multimedia and context based services, and the public Internet. Our architecture utilises packet marking and network level packet filtering techniques within a modified Mobile IPv6 protocol stack to perform access control over a range of wireless network technologies. In this paper, we describe the rationale for, and components of, our architecture and contrast our approach with other state-of-the- art systems. The paper also contains details of our current implementation work, including preliminary performance measurements
The evaluation of an active networking approach for supporting the QOS requirements of distributed virtual environments
This paper describes work that is part of a more general investigation into how Active Network ideas
might benefit large scale Distributed-Virtual-Environments (DVEs). Active Network approaches have been
shown to offer improved solutions to the Scalable Reliable Multicast problem, and this is in a sense the lowest
level at which Active Networks might benefit DVEs in supporting the peer-to-peer architectures considered
most promising for large scale DVEs. To go further than this, the key benefit of Active Networking is the ability
to take away from the application the need to understand the network topology and delegate the execution of
certain actions, for example intelligent message pruning, to the network itself. The need to exchange geometrical
information results in a type of traffic that can place occasional, short-lived, but heavy loads on the network.
However, the Level of Detail (LoD) concept provides the potential to reduce this loading in certain circumstances.
This paper introduces the performance modelling approach being used to evaluate the effectiveness of
active network approaches for supporting DVEs and presents an evaluation of messages filtering mechanisms,
which are based on the (LoD) concept. It describes the simulation experiment used to carry out the evaluation,
presents its results and discusses plans for future work
IETF standardization in the field of the Internet of Things (IoT): a survey
Smart embedded objects will become an important part of what is called the Internet of Things. However, the integration of embedded devices into the Internet introduces several challenges, since many of the existing Internet technologies and protocols were not designed for this class of devices. In the past few years, there have been many efforts to enable the extension of Internet technologies to constrained devices. Initially, this resulted in proprietary protocols and architectures. Later, the integration of constrained devices into the Internet was embraced by IETF, moving towards standardized IP-based protocols. In this paper, we will briefly review the history of integrating constrained devices into the Internet, followed by an extensive overview of IETF standardization work in the 6LoWPAN, ROLL and CoRE working groups. This is complemented with a broad overview of related research results that illustrate how this work can be extended or used to tackle other problems and with a discussion on open issues and challenges. As such the aim of this paper is twofold: apart from giving readers solid insights in IETF standardization work on the Internet of Things, it also aims to encourage readers to further explore the world of Internet-connected objects, pointing to future research opportunities
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