Doctoral dissertation
Dynamic composition of communication services
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Abstract
In this thesis, we look at networking functionality as a set of services which can be
composed dynamically. We argue that the dynamic composition of communication
services can speed up design and experimentation with new protocol stacks. The
reference Open Systems Interconnect (OSI) architecture of communication networks
splits network functionality into layers, each providing a service to the layer above. The
modularity provided by the OSI layered abstraction is further split in our approach by
looking also at layers as a set of services.
In order to substantiate our claim, we propose a conceptual framework for quick and
efficient prototyping and deployment of modular protocol stacks as a composition of
communication services, and its reference implementation ProtoStack. The proposed
framework consists of four components: the physical testbed, the module library, the
declarative language and the workbench. The physical testbeds that ProtoStack, as the
reference implementation, can support have to be based on hardware platforms which can
host Contiki operating system. The module library used by ProtoStack is called
Composeable Rime (CRime). The declarative language is based on the Resource
Description Framework (RDF) and uses a custom built vocabulary. The workbench is a
web based portal which allows easy, graphically supported configuration of a stack from
the available CRime modules.
We show, through feedback collection from first time users, that the ProtoStack tool
can significantly speed up prototyping and testing of new stacks and is friendly to novice
and advanced users. The initial feedback shows that the tool can speed up design and
prototyping of new protocol stack by at least a factor of 2. The cost of increased
flexibility and prototyping speed of the protocol stack is paid in terms of increased
memory footprint, processing speed and energy consumption. The CRime library used by
ProtoStack has a 16% larger footprint, it takes 2.4 times longer to execute an open->send-
>recv->close sequence and consumes 1.6% more power in doing so. Even though with
ProtoStack more resources are consumed by the node, the tradeoff in terms of prototyping
speed seems to pay off.
The last part of the thesis discusses service oriented networks (SON) and cognitive
networks (CN) and how the dynamic composition of communication services can be used
to further research in this area. Particularly, we show on selected use cases how
ProtoStack can be used to design and experiment with SONs and CN. The thesis ends
with conclusions and a brief discussion identifying future work.