| Summary: | The modern approach to complex services has some shortcomings which overcomplicate the implementation of application servers supporting service logic and also
the actual structure of these services. Modern service development environments
rely heavily on bearer network call/session signalling for the transport of service
messages to remote terminals and manipulating bearer streams in the network.
This research report looks at the overheads which occur when the bearer network is
used as the main transport for distributed service logic and then goes on to propose
application layer focused service development as a replacement for this. Service
logic developed in the application layer should be constrained to the application
layer so as to avoid leaky abstractions and make service development more intuitive
to programmers who do not have deep knowledge of telecommunications technologies
since the details of the bearer network do not play a part in the application layer.
Application layer signalling is introduced as a concept very important to keeping
service logic in the application layer, by allowing service messages to bypass the
bearer network. In this way, service sessions are started and maintained in the
application layer and lower-layer functionality is only called on when bearer network
streams are required by a service.
A framework is developed to support application layer focused service development.
This framework acts as support for decoupled service logic by allowing easy abstracted use of application layer signalling and bearer network functionality. It also
provides a simpli ed means for managing service logic. Reusability is also built
in in the form of reusable building blocks which abstract out various functionality
including that of the bearer network.
Using example services designed to be supported within the framework, the ideas
of application layer focused service development are proved to simplify service
development and o er robust support to services. Whilst this research report does
not attempt to standardise the technologies used to constrain service logic in the application layer, it does put forward important concepts which, when implemented,
would enhance service development environments by providing a strong platform on
which to develop services.
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