Time managment service over DDS


Published on

This presentation was presented in Siso Spring 2013. Know about the use of DDS for HLA time managment service.

Published in: Technology, Business
1 Like
  • Be the first to comment

No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide

Time managment service over DDS

  1. 1. Time managment service over DDS Presented by Jose R Martinez2013 Spring SIW
  2. 2. Speaker José Ramón Martínez Salio MSc Industrial Engineering AGENDA Presales Team Director NADS  Time Management overviewjrmartinez@nads.es  DDS and time management  Implementation  Questions Total time 30 minutes 2013 Spring SIW
  3. 3. Time managment overview2013 Spring SIW
  4. 4. Time Management Service: rationale • It started in HLA for coordinate simulators • Guarantee delivery of messages in right order • Make simulations repeatableThe function of time management service is the delivery ofmessages in order in a way consistent to all the federation 2013 Spring SIW
  5. 5. Time Management Service: Analysis Time management requisites • Has to cope with different time uses and necessities • Has to guarantee order and repeatability• Federators in HLA can be: • Time regulating: send messages that must be delivered in consistent order. • Time constrained: receive messages in consistent order• The way each federate uses time internally is transparent to the rest 2013 Spring SIW
  6. 6. Time Management Service: AnalysisAny Time management service has to implement• Time stamp order (TSO) message delivery service.• A protocol where federates explicitly request advances in their federate time, and the RTI guarantee no events will later arrive containing a smaller time stamp. TM I ES PED T AM T ESA P D IM T M E ES TM TM I APED 2013 Spring SIW
  7. 7. DDS and time management2013 Spring SIW
  8. 8. DDS and time management2013 Spring SIW
  9. 9. The Time Management Service in DDS• DDS provides mechanisms to guarantee order, repeatability and time management.• But, is that enough to cover time management service in HLA? 2013 Spring SIW
  10. 10. The Time Managment Service in DDSDDS “as is” is not enough. – DDS is oriented to real time. All the nodes are in the same time. Makes “strict” synchronization: all federates are in each moment in the last available time. Uses real time. – HLA uses “open” synchronization : all time-constrained federates are in every moment before (or can advance their own) the Federation time. Uses logical time. 2013 Spring SIW
  11. 11. The Time Managment Service in DDSOrder and timestamp – DDS allow to receive messages in reception order OR in timestamp order. – HLA allows receiving messages in reception order AND in timestamp order. 2013 Spring SIW
  12. 12. Implementation2013 Spring SIW
  13. 13. LSA Layers Overview Simulators; new and existing (included legacy) Current simulation architectures; HLA, DIS, TENA DDS simulators Arch specific APIs GatewaysSimulators TIME managementHLA DIS TENA Simulation ServicesDDS DDS DDS Common interface Data-centric Middleware: OMG DDSI Open Wire protocol 2013 Spring SIW
  14. 14. Creating Time Management in SimWare RTI• We are not using DDS communication layer – DDS is not enough – Open discussion: use of DDS in some cases. The standard allows the use logical times for time stamp. Implementation is not clear.• Time management is here a new layer over communication layer. Other layers Time management layer DDS-based communication layer 2013 Spring SIW
  15. 15. Time stamp order (TSO) message delivery service• We are building two message queues for time: – One for TSO (TimeStamp order) – One for RO (Receive order)• There is another queue for msg without time DDS DDS TSO queue RO queue 2013 Spring SIW
  16. 16. Coordinating time advance requestsThe lookahead problem in distributed networks – We are not yet fully distributed: use of central server. – With DDS is possible to distribute. – Open issue on latest version. Working on it. 2013 Spring SIW
  17. 17. Questions?2013 Spring SIW
  18. 18. Please address any questions about this presentation to: José Ramón Martínez Salio Technical Presales Director jrmartinez@nads.es2013 Spring SIW