Information Technology Reference
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Figure 6. High-level overview of the DART system, showing the various peers and their connectivity
the subsequent adverts. Moreover, when a super
peer in this scenario also plays the role of package
repository, it caches the downloaded file so that in
the future another package query can be matched
directly by this package repository. Replication
of the package on multiple package repositories
allows for a significant saving of time in the que-
rying phase and enables the concurrent retrieving
of packages from different repositories.
Once the worker has received the most up to
date package that it can find on the network, the
Triana taskgraphs are run and the algorithms begin
to analyze the audio files on the workers system
during the system's idle time. Once a package
cycle
is complete and the worker has results to
present, the worker then creates an XML advert
containing the results and metadata that gener-
ated by the algorithm specified in the package
(a
results advertisement
). As the actual results
generated would extremely small in size in this
DART system, the functionality of the Super
Peer has been extended in order to also cache
and make available.
The worker, who can be thought of a results
provider
on the DART system, can also act as
a
user
, as it can query for results (in this case
a suitable music/song suggestion as generated
on the super-peer). There is not a central results
collector, but rather DART utilizes a fully decen-
tralized model and allows the results to propagate
through the network hop by hop, to be stored on
the super peers. The super peers can process the
metadata and issue an XML
results advertise-
ment
on receipt of a
results query
from the user.
Once the query is received, the results may be
sent to the user.
In the package assignment phase the protocol
works in a way similar to the BOINC software,
except that package (or “job”) queries are not sent
directly to the DART manager, as in BOINC,
but travel the super-peer network hop by hop.
Conversely, the data download phase differs from
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