Moreover, since the aggregation function is executed on the server, the aggregation can be reused by multiple client applications (e.g., an aggregation of geo-localized messages by city region can be reused by a traffic monitoring and a "popular spots" application).
Twhirl provides persistence, aggregation of @replies, direct messages, and follow updates in a single stream, making it a better solution until recently when FriendFeed added real time support and, just yesterday, an import tool to synchronize Twitter follows as FriendFeed subscribers.
As a result both the aggregation time and number of messages are now bounded by O(N), as shown in our analysis.
By adding this push phase, we show that both the aggregation time and number of messages are bounded in EZ-AG by O(N).
We can see that automatic ARIMA modeling-based data aggregation scheme transmits much less number of messages than native data aggregation scheme for most of the times.
For synchronous changes, the performance of the two aggregation methodologies, i.e., number of messages and convergence speed, becomes comparable as the iterative variance reduction algorithm requires recomputation of the aggregates.
Thus, EZ-AG offers a poly-logarithmic factor improvement in terms of number of messages for hierarchical aggregation.
The required number of messages for data aggregation by EZ-AG in a connected, static network of N nodes with uniform distribution of node locations is O(N).
In Fig. 11a and b, we show the total number of messages and the total aggregation time as a function of network size for the aggregation protocol based on push-assisted self-repelling random walks.
As with TinyCOPS, it allows additional services such as aggregation to be incorporated, which control the dissemination of messages.
