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RealTimeDelay: How long should the operator wait in transaction time (real time) before it should send a punctuationApplicationTimeDelay: How long is the realTimeDelay in terms of application time (typically this should be the same, but for simulations this could be adapted)timeUnitTimeUnit: What is the time unit (see Java TimeUnit). Minimum Time unit is milliseconds!sendAlwaysHeartbeatSendAlwaysHeartbeat: If true, a heartbeat is send periodically for every realTimeDelay. This is useful for out of order processingallowOutOfOrderAllowOutOfOrder: If set to true, the operator allows heartbeats to be send, that lie before the last send element. In other cases this is not allowed.
Example
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output = |
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ASSUREHEARTBEAT({realTimeDelay=5000, |
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applicationTimeDelay=5000, |
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sendAlwaysHeartbeat='false', |
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allowOutOfOrder='false'}, |
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input) |
BUFFER
Description
Typically, Odysseus provides a buffer placement strategy to place buffers in the query plan. This operator allows adding buffers by hand. Buffers receives data stream elements and stores them in an internal elementbuffer. The scheduler stops the execution here for now. Later, the scheduler resumes to execution (e.g. with an another thread).
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This operator can be used to reduce data rate. It buffers incoming elements on port 0 (left) for bufferTime and evaluates a predicate over the elements on port 1 (right). If the predicate for the current element e evaluates to true, all elements from port 0 that are younger than e.startTimeStamp()-bufferTime will be enriched with e and delivered for deliverTime. Each time the predicate evaluates to true, the deliverTime will be increased.
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Predicate: The predicate that will be evaluated on element of port 1BufferTime:The time in history, the elements will be kept in historyDeliverTime:The time in the future, the elements will be delivered
Example
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output = BUFFEREDFILTER({predicate = RelationalPredicate('id == 2 || id == 4 || id == 10'), bufferTime = 5000, deliverTime = 20000}, |
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left, right) |
CALCLATENCY
Description
Odysseus has some features to measure the latency of single stream elements. This latency information is modeled as an interval. An operator in Odysseus can modify the start point of this interval. This operator sets the endpoint and determines the place in the query plan, where the latency measurement finds place. There can be multiple operators in the plan, to measure latency at different places.
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