Active group communication.
This thesis explores the application of active networking (A.N.) to
group communication. A.N. adds programmable computation platforms
to the nodes that form the switching fabric of the network. By leveraging
these new facilities we can make the development of complex protocols
easier and provide new 'value-added' services to the network infrastructure.
Active networking is a relatively new research area. There are
popular toolkits but no overall agreements. We examine this field in detail
exploring its benefits and pitfalls. We explore the problems of simulating
A.N. and possible solutions. We describe NetSim a network simulator
we have developed to meet the goals of A.N. simulation. Writing A.N.
protocols is far more difficult than writing conventional protocols. We
must consider not only the end-points of communication, but also the
switching hardware within the network. We show the inherent complexity
can be addressed by abstraction and the use of frameworks. We demonstrate
AFrame, an active service that supplies both communication and local
information to active agents at each node. This framework abstracts and
hides some of the complexities of communication. We use this framework
to develop new information agents and higher-level protocols.
We have constructed the Active Multicast Framework (AMF) to
show how programming techniques (abstraction and object-oriented) can
be applied to the complex area of group communication. We use A.N. to
simplify and improve current multicast and group communication protocols
and show implementations of best effort, reliable and ordered multicast.
We leverage AMF to show that novel protocols can be developed. Using
processing power within the network allows us to develop new breeds of
protocols. To show this we developed ATOM, an efficient, fair, totally
ordered multicast implementation. We achieve our goal of demonstrating
the benefits of applying A.N. technology to group communication and the
strengths of good frameworks.