Semantic CEP

This wiki page reports on the activities around the Semantic Complex Event Processing (SCEP) within RSP. We want to leverage RSP-QL to support some level of SCEP by identifying what is missing and characterizing short- and long- term goals.

Key Ideas

• Use RSP to reduce the input at CEP level
• Enable State Management to define operators for summarization/aggregation
• Ability to feed back results into the stream (loop-back new stream?)
• Would that scale? Implementation can be different than RSP-QL language specification
• Application dependent aspects (long-term)
  • Mathematical operators
  • Geospatial calculation

Windowing

• time interval
• tumbling windows in CEP

Managing Graphs

• Need to uniquely identify a graph to refer to it later
• Same named graph (one event) could have unique identifier but different timestamps

State Management

• Access to timestamps (e.g. for partial computation of substreams)
• Store state of previous event

Stateful operators

• SEQ (need optional binding), REP
• Clean Closure (e.g. same event with different temporal values)
• Selection strategies (e.g. skip till next)
• Correlations of results of sub-patterns into one query
• More longer-term: property paths, nested construct queries, negation, ...

Implementation Issues

This is a longer-term aspect of SCEP activities within RSP. The key point to keep in mind for now is that the implementation can happen by extending specific engines or as part of a new engine implementing RSP-QL with embedded SCEP.