Package net.sf.eBus.feed Description

This package contains specialized feeds extending the basic feeds in net.sf.eBus.client. Currently this package consists only of pattern feeds but there are more planned such as:

historical/live feed: the ability to access both historical and/or live updates across one feed.
active/stand-by reply feed: allows two or more ERepliers for the same message key to be placed into active and stand-by status. All repliers will see matching requests but only the active replier's response is posted back to the requestor. If the active replier advertisement is lost, the a stand-by replier takes over as active.
replier load balancing: requests are distributed across multiple repliers based on a configured load balancing scheme.

Pattern Notification Feeds

eBus v. 4.6.0 introduced pattern feeds. A pattern feed monitors one or more notification feeds looking for a series of events which match a user-defined pattern. When a matching event series is found, a MatchEvent is posted to the subscriber. MatchEvent contains all the matching events and user-defined capture groups.

There are two pattern types: ordered and unordered. Ordered patterns are a simple event regular expressions. Each construct has the form [one or more event names]{n, m} where the specified events must appear at least n times and at most m times. Events must arrive in exactly the ordered specified by the pattern to make a match.

Unordered patterns specify how many of each event type must be received to match the pattern. If a pattern states that between 3 and 5 stock trade events and 1 to 2 stock quote events are needed, then any mix of trade and quote events satisfying these counts matches the pattern.

See EventPattern and EPatternFeed to learn how to create patterns and use pattern feeds.