Query Lifecycle

Legend

• S2R = Stream to Relation Operators
• R2R = Relation to Relation Operators
• R2S = Relation to Stream Operators
• TVG = Time-Varying Graph
• SDS = Streaming Data Set
• CQE = #Continuous Query Execution

Passages

0. Consume the S2R operator is start consumeing a stream
1. The stream notifies the consumers, i.e., the data item is passed to the S2R operators
2. the Continuous Query Execution starts observing the S2R operators
3. the S2R operators update the CQE when it is time to compute (according to the Execution Semantics)
4. The CQE triggers the materialization of the SDS at the given time instant (in ET)
5. the SDS iteratively triggers the materialization of the Time-Varying Graph it contains.
6. the CQE triggers the evalution of the R2R over the materialized SDS.
7. For each results in the R2R evaluation, the R2S is evaluated
8. The R2S writes over the output stream

Continuous Query Execution

public interface ContinuousQueryExecution<I, E1, E2> {

    WebDataStream<E2> outstream();

    ContinuousQuery query();

    SDS<E1> sds();

    StreamToRelationOp<I, E1>[] s2rs();

    RelationToRelationOperator<E2> r2r();

    RelationToStreamOperator<E2> r2s();

    void add(StreamToRelationOp<I, E1> op);

    Stream<SolutionMapping<E2>> eval(Long now);
}