SLAMorris Final Thesis After Corrections.pdf - Cranfield University

However, if this ‘tampered’ record is selected, a new visual thumbnail is shown
which accurately represents the file. The tampered record is not, however
overwritten in the thumbnail cache. Instead the accurate image is generated
when required, by the system and does not appear to be stored anywhere. If
the browser is refreshed or reopened, the tampered thumbnail is still displayed
until the file is selected; the accurate image is only displayed and not saved in
the thumbnail cache.
5.8.3 Original source file
If a new file is placed at a URI with an existing subrecord entry in the thumbnail
cache, then both Ubuntu and Kubuntu will update the thumbnail cache entry.
However, if the associated last modified time in the subrecord is altered to
match the new source file, Ubuntu will not update its subrecord entry. Kubuntu
appears to perform a greater number of checks on the information in the
subrecords and appears to regenerate a record if the visual thumbnail does not
accurately reflect the original source files state. Experiments corroborated this
finding, as two identical files were viewed, one of which had a tampered
subrecord; only the modification time for the subrecord which had been
tampered with was updated, suggesting the subrecords are not simply
regenerated on access.
5.9 Forming a relationship between the thumbnail subrecords
and the source files
Previous sections have established the requirement to put thumbnail cache
artefacts in the context of the user actions which generated them. This section
looks at ways in which a relationship between a subrecord and an original
source file could be formed.
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