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QoS-Aware Publish-Subscribe Service for Real-Time Data Acquisition. Xinjie Lv, Xin Li, Tian Yang, Zaifei Liao, Wei Liu, Hongan Wang. Outline. Expression of QoS of Pub-Sub Enforcement of QoS of Pub-Sub Case Study-A simple application with three requirements Conclusion. Related works.
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QoS-Aware Publish-Subscribe Service for Real-Time Data Acquisition Xinjie Lv, Xin Li, Tian Yang, Zaifei Liao, Wei Liu, Hongan Wang
Outline • Expression of QoS of Pub-Sub • Enforcement of QoS of Pub-Sub • Case Study-A simple application with three requirements • Conclusion • Related works
Publish-Subscribe Service • Applications:
Why Publish-Subscribe Service • Advantages • Space decoupling do not need to know each other. • Time decoupling do not need to be actively participating in the interaction at the same time. • Synchronization decoupling publishers are not blocked and subscribers can get asynchronous notification.
Existing Models and Systems • Models • CORBA Event Service • CORBA Notification Service • Java Message Service (JMS) • Systems • Cambridge Event Architecture (CEA) • Distributed Asynchronous Collections (DAC) • Scalable Internet Event Notification Architectures (SIENA)
Problem • Limited support for the expression of Quality of Service (QoS) parameters • Limited support for the enforcement of QoS parameters • Limited support for the Real-Time and active capabilities
Expression of QoS-DDS • Data Distribution Service • Specification from the Object Management Group (OMG) • Aiming at users requiring data-centric publish-subscribe communications • Enumerating and providing formal definitions for the QoS settings
Outline • Related works • Enforcement of QoS of Pub-Sub • Case Study-A simple application with three requirements • Conclusion • Expression of QoS of Pub-Sub
Expression of QoS-DDS • Data-Centric Publish-Subscribe (DCPS): efficient delivery of the proper information to the proper recipients. • Data Local Reconstruction Layer (DLRL): integration into the application layer. DCPS conceptual model
Expression of QoS-DDS • Supported QoS of DDS
Outline • Related works • Expression of QoS of Pub-Sub • Case Study-A simple application with three requirements • Conclusion • Enforcement of QoS of Pub-Sub
Enforcement of QoS-QRTPS • QoS-aware Real-Time Publish-Subscribe (QRTPS) service based on an active real-time database named Agilor • Overview of Agilor • Real-time Event-Condition-Action (RECA)
Enforcement of QoS-Agilor • kernel modules and critical services in Agilor
Enforcement of QoS-RECA • Primitive events in Agilor: • system events • method events • custom events • Extension of Complicated Temporal Events • Durative event, Durative sequence • Durative conjunction, Durative disconjunction • Durative between
Enforcement of QoS-RECA • Primitive conditions in Agilor: • Selection condition: OP.Gas>20 • Aggregation condition: Max(OP.smog)>100 • Join condition: OP1.Pressure= OP2.Pressure • Transition condition: OP1.Gas> OP1.GetLast (Gas) • Application-specific condition
Enforcement of QoS-RECA • Actions in Agilor: • database operations: deletion, update • external actions: publish data, signal an alarm. • deadline assigned to the action: relative to the occurrence time of the triggering event.
Enforcement of QoS-RECA • Coupling Modes in Agilor: CMEC: Event-Condition; CMCA: Condition-Action CMEA: Event-Action; CMRR: Rule-Rule • Semantic for RECA Rules Rule::=BEGIN RULE <RuleName> VALUE <Value> WHEN <Event> IF <Condition> CMEC [immediate|detached] CMEA [immediate|detached] THEN <Action> WITHIN <Deadline> CMCA [immediate|detached] CMRR [immediate|concurrent] END RULE
Outline • Related works • Expression of QoS of Pub-Sub • Enforcement of QoS of Pub-Sub • Conclusion • Case Study-A simple application with three requirements
Case Study-Overview • Real-Time monitoring in a coal mine
Case Study-Requirements • Three requirements: 1.Late-joining applications shall receive meta information about its sensors automatically; 2.Receiving gas sensor data every 500ms and temperature data every 1000ms; 3.If no data from most-trusted sensor source is received within 4000ms, temperature data shall automatically be received from another Observation Point (OP).
Case Study-Data Structures • Gas : transmitting the sensor readings • GasSensorlnfo :containing meta-information to interpret the sensor data correctly
Outline • Related works • Expression of QoS of Pub-Sub • Enforcement of QoS of Pub-Sub • Case Study-A simple application with three requirements • Conclusion
Conclusions • Expressing QoS with DDS • Enforcing QoS policy with Agilor • Improving Real-time and active capabilities with RECA • Evaluating QRTPS for a Real-time monitoring