Abstract
In large content-based multi-attribute publish /subscribe systems, event matching is a key component, which is in charge of finding all subscriptions that match events. However, the increasing user scale, the enriching message diversity, and the aggravating QoS demands make the performance of event matching severely challenged. Most existing event matching schemes cannot efficiently sustain in these scenarios. The performance rapidly drops as the system load rises. In this paper, we propose GEM-Tree (Geometrical Event Matching Tree), a novel tree-based analytic geometrical index structure for highly efficient event matching in large-scale content-based publish/subscribe systems. To further improve the event matching speed, a local-adjustment mechanism is designed to determine the deployment for each new subscription registering into the GEM-Tree, and a global-adjustment mechanism is designed to optimize the locations of the subscriptions already inserted in GEM-Tree. The experiment results in 8 scenarios demonstrate that GEM-Tree is superior to 3 state-of-the-art reference schemes(BE-Tree, OP-Index, and TAMA). Especially, the leading advantage of GEM-Tree is more significant in matching time for a large number of subscriptions.
Highlights
Publish/subscribe(pub/sub) is an anonymous, many-to-many asynchronous messaging model with full decoupling of the communication parties in time, space and synchronization [1]
We introduce GEM-Tree in detail, including the overall structure of GEM-Tree, the attribute value interval is mapped to the right triangle structure, which is the essential part of the event matching performance improvement, the ranking function, which plays a key role in the dynamic construction of GEM-Tree
This paper introduces GEM-Tree, an efficient index structure to improve the event matching for multi-dimensional contentbased pub/sub services
Summary
Publish/subscribe(pub/sub) is an anonymous, many-to-many asynchronous messaging model with full decoupling of the communication parties in time, space and synchronization [1]. Because BE-Tree dynamically adjusts the index structure based on the inserted subscriptions, the extra costs brought by the above interval division will have negative influences on event matching. When the subscription is inserted, the right triangle structure is responsible for the division of the attribute values, and the local-adjustment mechanism dominates the location of subscriptions in GEM-Tree.
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