Dynamically managing sensed context data

Ritchie, Martin A. (2005) Dynamically managing sensed context data. MSc(R) thesis, University of Glasgow.

Abstract

This thesis reports on an investigation of the feasibility and usefulness of incorporating
dynamic management facilities for managing sensed context data in a distributed contextaware
mobile application. The investigation focuses on reducing the work required to
integrate new sensed context streams in an existing context aware architecture.
Current architectures require integration work for new streams and new contexts that
are encountered. This means of operation is acceptable for current fixed architectures.
However, as systems become more mobile the number of discoverable streams increases.
Without the ability to discover and use these new streams the functionality of any given
device will be limited to the streams that it knows how to decode.
The integration of new streams requires that the sensed context data be understood
by the current application. If the new source provides data of a type that an application
currently requires then the new source should be connected to the application without any
prior knowledge of the new source. If the type is similar and can be converted then this
stream too should be appropriated by the application.
Such applications are based on portable devices (phones, PDAs) for semi-autonomous
services that use data from sensors connected to the devices, plus data exchanged with
other such devices and remote servers. Such applications must handle input from a variety
of sensors, refining the data locally and managing its communication from the device in
volatile and unpredictable network conditions. The choice to focus on locally connected
sensory input allows for the introduction of privacy and access controls. This local control
can determine how the information is communicated to others.
This investigation focuses on the evaluation of three approaches to sensor data management.
The first system is characterised by its static management based on the pre-pended
metadata. This was the reference system. Developed for a mobile system, the data was
processed based on the attached metadata. The code that performed the processing was
static.
The second system was developed to move away from the static processing and introduce
a greater freedom of handling for the data stream, this resulted in a heavy weight
approach. The approach focused on pushing the processing of the data into a number of
networked nodes rather than the monolithic design of the previous system. By creating a
separate communication channel for the metadata it is possible to be more flexible with
the amount and type of data transmitted.
The final system pulled the benefits of the other systems together. By providing a
small management class that would load a separate handler based on the incoming data,
Dynamism was maximised whilst maintaining ease of code understanding.
The three systems were then compared to highlight their ability to dynamically manage
new sensed context. The evaluation took two approaches, the first is a quantitative
analysis of the code to understand the complexity of the relative three systems. This was done by evaluating what changes to the system were involved for the new context. The
second approach takes a qualitative view of the work required by the software engineer to
reconfigure the systems to provide support for a new data stream.
The evaluation highlights the various scenarios in which the three systems are most
suited. There is always a trade-o↵ in the development of a system. The three approaches
highlight this fact. The creation of a statically bound system can be quick to develop but
may need to be completely re-written if the requirements move too far. Alternatively a
highly dynamic system may be able to cope with new requirements but the developer time
to create such a system may be greater than the creation of several simpler systems.

• Item Type: Thesis (MSc(R))
• Qualification Level: Masters
• Subjects: Q Science > QA Mathematics > QA75 Electronic computers. Computer science; Q Science > QA Mathematics > QA76 Computer software
• Colleges/Schools: College of Science and Engineering > School of Computing Science
• Supervisor's Name: Gray, Phil. and Dickman, Peter
• Date of Award: 2005
• Depositing User: Mrs Marie Cairney
• Unique ID: glathesis:2005-7510
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 05 Aug 2016 10:06
• Last Modified: 08 Aug 2016 08:37
• URI: https://theses.gla.ac.uk/id/eprint/7510