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The "HedWig" page has been changed by mahadevkonar. http://wiki.apache.org/hadoop/HedWig?action=diff&rev1=3&rev2=4 -------------------------------------------------- Hedwig is a '''publish-subscribe''' system designed to carry large amounts of data across the internet in a '''guaranteed-delivery''' fashion from those who produce it ('''publishers''') to those who are interested in it ('''subscribers'''). The goals of Hedwig are: - 1 *Guaranteed Delivery*: The messages may not be lost even when a particular subscriber goes offline for extended periods of time. + 1. '''Guaranteed Delivery''': The messages may not be lost even when a particular subscriber goes offline for extended periods of time. - 1 *Topic-based*: Publishes and subscribes happen to a topic. The system should scale to ~10^6 topics with ~10 subscribers on each topic. + 1. '''Topic-based''': Publishes and subscribes happen to a topic. The system should scale to ~10^6 topics with ~10 subscribers on each topic. - 1 *Incremental Scalability*: It should be possible to scale capacity by adding servers on the fly. The up-front hardware investment should not be huge. + 1. '''Incremental Scalability''': It should be possible to scale capacity by adding servers on the fly. The up-front hardware investment should not be huge. - 1 *High availability*: The system should remain available in the presence of single server failure without manual intervention. + 1. '''High availability''': The system should remain available in the presence of single server failure without manual intervention. While there are a lot of commercial and open-source products in the general pub-sub category, none of them satisfy all the above 4 requirements (they mostly fail on 3 and 4).
