Roxana - Gabriela HORINCAR Refresh Strategies and Online ... - LIP6

The query processing approach is outside the scope of our research, but related work can
be found in [TATV11].
Publisher: This module is responsible for transforming the results generated by the
query processor into different output formats. The standard scenarios are to generate a
new RSS query feed for each aggregation query and publish them for the user consumption
or store them in a database for archiving purposes. Other output formats are also possible
(SMS, email, Atom feed).
1.6 Feed Aggregation Network
The query feeds generated and published by an aggregator can also serve as input source
feeds for other aggregators. If we compose several such aggregators nodes we obtain a feed
aggregation network with continuous information diffusion paths.
Each node in the sharing graph can have the hybrid role of a data source and consumer
in the same time, as can be seen in Figure 1.5. Nodes that have only a source role create
new data and represent the entry points of the information in the system. The nodes
with consumer roles are characterized by their different interests in the data produced by
the sources. They can by interested by the entire information produced by a source, or
only by a part of it, interests defined by different aggregation queries. As a node receives
information from other source nodes, it can further distribute it into the system, having
thus a hybrid producer-consumer role.
Figure 1.5: Feed aggregation graph
In the following sections, we introduce a feed aggregation subscription graph model and
propose a method to construct the topology of such a network, inspired by the Internet
topology.
16