Page History

...

• FIRST: The first element
• LAST: The last element
• NTH: The nth element
• RATE:??

...

ASSUREHEARTBEAT

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).

Parameter

• Type: The type of the buffer. The following types are currently part of Odysseus:
  
  • Normal: This is the standard type and will be used if the type parameter is absent
  • Currently, no further types are supported in the core Odysseus. In the future, there will be some buffers integrated to treat prioritized elements.
• MaxBufferSize: If this value is set, a buffer will block if it reaches its maximal capacity. No values will be thrown away; this is not a load shedding operator!

Example

BUFFEREDFILTER

Description

This operator can be used to reduce data rate. It buffers incoming elements on port 0 for bufferTime and evaluates a predicate over the elements on port 1. 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.

Parameter

• Predicate: The predicate that will be evaluated on element of port 1
• BufferTime: The time in history, the elements will be kept in history
• DeliverTime: The time in the future, the elements will be delivered

Example

BufferedFilter({predicate = RelationalPredicate('id == 2 || id == 4 || id == 10'), bufferTime = 5000, deliverTime = 20000}, nexmark:bid2, nexmark:person2)

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.

Parameter

Example

CHANGEDETECT

Description

This operator can be used to filter out equal elements and reduce data rate.

Parameter

• ATTR (List<String>): only these attribute are considered for the comparison
• Heartbeatrate (Integer): For each nth element that is filtered out, a heartbeat is generated to state the progress of time
• deliverFirstElement (Boolean): If true, the first element will be send to the next operator.

DIFFERENCE

Description

This operator calculates the difference between two input sets.

Parameter

None

Example

diff = difference(mapped, projected)

ENRICH

Description

This operator enriches tuples with information from the context store. Further Information: http://odysseus.offis.uni-oldenburg.de/twiki/bin/view/Main/ContextStore

Parameter

• ATTRIBUTES: The attributes from the store object, that should be used for enrichment
• STORE: The name of the store
• OUTER:

Example

ENSUREHEARTBEAT

Description

This operator assures that there will be periodically a heartbeat to avoid blocking because of missing information about time progress. The operator garantees, that no element (heartbeat or streamobject) is send, that is older than the last send heartbeat (i.e. the generated heartbeats are in order and indicate time progress). Heartbeats can be send periodically (sendAlwaysHeartbeats = true) or only if no other stream elements indicate time progess (e.g. in out of order scenarios) independent if a new element has been received or not.

Parameter

• RealTimeDelay: How long should the operator wait in transaction time (real time) before it should send a punctuation

• ApplicationTimeDelay: How long is the realTimeDelay in terms of application time (typically this should be the same, but for simulations this could be adapted)

• timeUnit: What is the time unit (see Java TimeUnit). Minimum Time unit is milliseconds!

• sendAlwaysHeartbeat: If true, a heartbeat is send periodically for every realTimeDelay. This is usefull for out of order processing

• allowOutOfOrder: 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

...

This operator assures that there will be periodically a heartbeat to avoid blocking because of missing information about time progress. The operator garantees, that no element (heartbeat or streamobject) is send, that is older than the last send heartbeat (i.e. the generated heartbeats are in order and indicate time progress). Heartbeats can be send periodically (sendAlwaysHeartbeats = true) or only if no other stream elements indicate time progess (e.g. in out of order scenarios) independent if a new element has been received or not.

Parameter

• RealTimeDelay: How long should the operator wait in transaction time (real time) before it should send a punctuation

• ApplicationTimeDelay: How long is the realTimeDelay in terms of application time (typically this should be the same, but for simulations this could be adapted)

• timeUnit: What is the time unit (see Java TimeUnit). Minimum Time unit is milliseconds!

• sendAlwaysHeartbeat: If true, a heartbeat is send periodically for every realTimeDelay. This is usefull for out of order processing

• allowOutOfOrder: 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

out = AssureHeartbeat({realTimeDelay=5000, APPLICATIONTIMEDELAY=5000, SENDALWAYSHEARTBEAT='false', ALLOWOUTOFORDER='false'},nexmark:person2)

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).

Parameter

• Type: The type of the buffer. The following types are currently part of Odysseus:
  
  • Normal: This is the standard type and will be used if the type parameter is absent
  • Currently, no further types are supported in the core Odysseus. In the future, there will be some buffers integrated to treat prioritized elements.
• MaxBufferSize: If this value is set, a buffer will block if it reaches its maximal capacity. No values will be thrown away; this is not a load shedding operator!

Example

BUFFEREDFILTER

Description

This operator can be used to reduce data rate. It buffers incoming elements on port 0 for bufferTime and evaluates a predicate over the elements on port 1. 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.

Parameter

• Predicate: The predicate that will be evaluated on element of port 1
• BufferTime: The time in history, the elements will be kept in history
• DeliverTime: The time in the future, the elements will be delivered

Example

BufferedFilter({predicate = RelationalPredicate('id == 2 || id == 4 || id == 10'), bufferTime = 5000, deliverTime = 20000}, nexmark:bid2, nexmark:person2)

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.

Parameter

Example

CHANGEDETECT

Description

This operator can be used to filter out equal elements and reduce data rate.

Parameter

• ATTR (List<String>): only these attribute are considered for the comparison
• Heartbeatrate (Integer): For each nth element that is filtered out, a heartbeat is generated to state the progress of time
• deliverFirstElement (Boolean): If true, the first element will be send to the next operator.

DIFFERENCE

Description

This operator calculates the difference between two input sets.

Parameter

None

Example

diff = difference(mapped, projected)

ENRICH

Description

This operator enriches tuples with information from the context store. Further Information: http://odysseus.offis.uni-oldenburg.de/twiki/bin/view/Main/ContextStore

Parameter

• ATTRIBUTES: The attributes from the store object, that should be used for enrichment
• STORE: The name of the store
• OUTER:

Example

EVENTTRIGGER

Description

Parameter

...