Send on delta

This processor employs a highly efficient send-on-delta algorithm, leveraging user-defined fields to ascertain whether a new event exhibits changes in these specified fields. Only unique events that demonstrate alterations are forwarded to interconnected components.

Example

send on delta:
  fields:
    - symbol
    - bid
    - ask
  expected unique events: 100000
  fpp: 0.98

This will publish unseen delta events to the next processor.

Attributes

Attribute	Description	Data Type	Required
fields	Javascript expression that returns a boolean value	List<String>
expected unique events	Expected unique events. This must be calculated correctly otherwise false positives will be generated as the number approaches and breaches the provided number. Minimum number of events is 100 otherwise the filter cannot be created.	Long
fpp	The desired false positive probability. Must be positive and less than 1.0	Double Default: 0.97
reset by time delay	Reset the bloom filter after a set number of seconds.	Long Default: 0
reset by event count	Reset the bloom filter after a set number of events processed.	Integer Default: 0

Filter replacement

The processor uses a BloomFilter to determine if an event has been seen before. Therefore the filter is automatically updated when there is a high probability of false positives being generated.

Any StreamEvent which has the deltaBreachedFPP field will signify a filter change once the event has been published.

Note

Both of the reset functions can be applied.