ANN: Kamaelia - A Network Testbed

Michael Sparks michaels at
Mon Dec 20 15:43:51 CET 2004

Kamaelia - A Network Testbed

I'm very pleased to be able to be able to announce the release of the
BBC's R&D KAMAELIA project under open source licensing terms to all
potential collaborative partners in the network community.

Kamaelia is collection of python modules designed as a network
experimentation testbed for network protocol research. Its
architecture is specifically designed to simplify creation and
testing of new protocols for large scale media delivery systems.

Many network researchers use the open source TCP/IP stacks for
investigating/improving low level transport protocols. Likewise,
many network caching researchers use similar testbeds (eg squid)
for experimentation and collaboration. The intent for Kamaelia
is similar. Kamaelia is designed to enable use as a media server
experimentation toolkit.

Kamaelia is a work in progress, and has gone through a number of
iterations to date. This initial release is a small stable subset of
what we hope can be created using this system, but more importantly we
feel provides a base for future experimentation. We do not expect to
get the right answers first time round, but by sharing with the
community we hope to stimulate development in this area.

Kamaelia uses the Python programming language, created by Guido van
Rossum. Python was chosen for its facilities: resumable functions, its
clarity of code and compact nature. However, Kamaelia is designed to
provide a framework for collaboration, so we hope that the approach
will be available to other network researchers in other languages as
the project progresses.

The aim of releasing Kamaelia is to work with participants inside the
IETF and similar organisations for the creation of open protocols and
standards designed for large scale media delivery. It is hoped that the
result of such a process would be to stimulate vendors who can then
confirm the results of our research and implement any resulting open
protocols in their products in much the same manner as many earlier

But what is it?
A collection of python generators running concurrently linked via
communications channels.

Components are written as python generators. The approach for building
components and systems is similar to using Unix command line pipes, CSP
and hardware. Specifically you write small focussed components which
only know about their local inputs and outputs. Interesting systems are
then composed using linkages, creating networks of components linking
outboxes to inboxes, in a similar way that unix pipelines create
interesting systems by linking stdout to stdin between successive

This differs from many other systems in that it doesn't use essentially
a state machine based approach, rather relying on the python language
to provide the basic concurrency requirements. This approach is however
somewhat experimental, and at this stage not as efficient, however this
will change. If you are looking to build a production system Kamaelia
is probably not appropriate at present.

Take a TCP server as an example. You have a generic TCP server component
that accepts a protocol component. That server component handles then
everything except the actual protocol. The work in creating (and hence
testing and experimenting) is then limited to just writing your
protocol. You don't have to consider basic network server scaling
issues, you don't need to restructure your protocol to fit a framework
(thereby making it more difficult to experiment with the protocol), you
just write the protocol. You can also test the protocol in isolation
from the network, making protocol testing and compliance testing
significantly simpler.

The key difference from traditional software systems is that people are
able to write new components and network protocols for the system using
simple techniques to integrate with a larger testbed framework. The
approach is inspired directly from the techniques used for asynchronous
hardware construction. More documentation will be added as we do on,
but for now there is documentation in the CVS tree. (See download

What Stage Is The Project At ?
We have recently made our code available as a CVS release for developers
who are interested at this stage. We are moving documentation and
material describing the motivation into both the website and
documentation. The project changed to a largely test-first approach
late in the project, and some test suites are being implemented.
However the core of the system, Axon, we believe to be largely
feature complete given that it's functionality has been driven
by application spikes. The Kamaelia system itself is now largely
complete for building TCP based servers - the most common class
of network server. A small number of trivial example protocols are

Website, Email lists

Kamaelia is only available as a developer CVS release at present. A hosted project has been created to allow open process,
and to allow working reference solutions to be shared in the hope of
encouraging consensus. 

Please go to the sourceforge project page and perform a CVS checkout,
read the tests, and feel free to play/feedback:

Kamaelia is released under the Mozilla tri-license scheme
(MPL/GPL/LGPL). Specifically you may choose to accept either
the Mozilla Public License 1.1, the GNU General Public License
2.0 or the Lesser General Public License 2.1. Proprietary terms
and conditions available upon request.

The development of Python is managed by the Python Software Foundation is a trademark of VA Software Corporation

Merry Christmas,

Michael Sparks
Michael.Sparks at    
British Broadcasting Corporation, Research and Development
Kingswood Warren, Surrey KT20 6NP

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