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SIRI - Service Interface for Real Time Information (CEN-OO278181 ) siri.uk

SIRI - Service Interface for Real Time Information (CEN-OO278181 ) http://www.siri.org.uk. 27- 29 Cursitor Street London, EC4A 1LT nick_knowles@kizoom.com Siri 0.1g v3.6b. Topics. General Background Transport & Communications Specific Functional Services Review Process and Completion.

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SIRI - Service Interface for Real Time Information (CEN-OO278181 ) siri.uk

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  1. SIRI - Service Interface for Real Time Information (CEN-OO278181 ) http://www.siri.org.uk 27- 29 Cursitor StreetLondon, EC4A 1LT nick_knowles@kizoom.com Siri 0.1g v3.6b

  2. Topics • General Background • Transport & Communications • Specific Functional Services • Review Process and Completion

  3. General Background& Overview

  4. SIRI - CEN TC278 WG3 SG7 • Real-time Server-to-Server Services for PTVs • Based on: • TransModel : Terminology, model (isomorphic) • XML, WS-PubSub  Web Service enabled • VDV 453,454, Trident, RTIG – Real systems & experience! • Useful for Specifying & Implementing AVMS, PTI and UTMC systems • European economies of scale • Participants • Germany (VDV453, VDV 454) • France (Trident , TransModel) • UK (RTIG-XML, TransModel) • Denmark, Sweden, Norway, (PubTrans) • Deliverables (April 2005) • Technical Standard Document (for consultation) • Supporting XML Schema – W3C .XSD • Support WSDL /SOAP binding using same xsd schema • Migration path from existing standards

  5. Gene Pool

  6. Motivation - Uses Of SIRI Services • Rapid growth in real-time info - makes PT more efficient & more attractive to use. • Provision of Real time Service Information to Passengers. • At Stop, On board, tethered & mobile internet • Provision of Information to Journey Planners. • Real-time augmented • Facilitating Connections for Passengers. • PT Fleet and Network Management. • General Business Communication.

  7. Motivation - Standards • Value to PTEs / Customers • Open architectures & supplier independence. • Protection of investment. • Efficient tender specification criteria. • Value to Suppliers • European economies of scale & markets. • Reduced complexity & deployment costs • More reuse, Cheaper integration • Simplified tendering, quality differentiator. • Value to Both • Enables new types of services • Lowers costs - creating new markets • Modern, Modular, scaleable architectures • Harnesses open internet standards

  8. Support Different Operation Models • Interfaces can be used for different operational models

  9. Support Different Environments • Able to optimise for different operational characteristics • High/Low bandwidth • Fast/slow processors • Hi/Low traffic • Large/small networks • Sparse /dense usage • Able to optimise for different operational characteristics

  10. Technical Challenges • How to give migration path from existing standards • VDV, RTIG, TRIDENT • Allow alternative delivery patterns • Allow alternative formats for some detailed response messages where necessary. Semantically identical. • Allow modular, incremental implementation: roadmap • What is canonical TransModel XML? • Trident XML not being kept current • Further improvements in TransModel since Trident • New developments/standards in XML / WS technology • Further application requirements for SIRI • What real-time efficiency optimisations are needed? • Principle of strict Transmodel Isomorphism ? • Allow different message patterns and tradeoffs

  11. SIRI Approach & Services • Separation of Concerns • Transport layer is separate (http &/or SOAP) • SIRI General Communications Services • Common to all types of Functional Service • Robust, scaleable, architecture for Real Time • Tuneable for efficient deployment • SIRI Functional Services • Timetables & Timetable Changes • Stop Events (Arrivals & Departures) • Vehicle Movement • Connection Protection (Timetables, Events) • General Informative Messages

  12. SIRI is an XML Dynamic Protocol • What to Exchange? • Message Payload Structure • Content model Requests, responses, • Derived from TransModel + National systems • Data reference systems • Stop identifiers, Lines, times etc • How to Exchange it? • Protocols & message patterns • Transport • Mediation • Derived from existing National systems

  13. Transport & General Communications

  14. General Communications Services #1 • Common Protocols for all SIRI Functional Services • Independent of Functional Message Content • Based on new Web services standard Ws-PubSub, Ws-Address etc (W3C) • Communications Transport Independent • XML + http POST, • WSDL SOAP Binding

  15. SIRI Communications Layer • Common to all Functional Services

  16. General Communications Services #1 • General Functions Common to all SIRI Service Types • Subscription Management • Recovery & Restart • Access Controls • Versioning • Discovery • Some Capabilities are Optional

  17. General Communications Services #2 • Alternate Patterns of Interaction • Request/Response vs. Publish/Subscribe • Choose for scaleability & responsibility • Direct Delivery vs. Fetched Delivery • Allows efficient implementation choices • Notification Mediation • Reduces traffic for publish subscribe • Last Update, Change Threshold, • Subscriber Groups

  18. Interaction 1- Request/Response

  19. Interaction 2- Publish/Subscribe

  20. Publish Subscribe -WS-PubSub • New Coherent Family of web service standards for stateful patterns of interaction . IBM, Microsoft, Tipco, Akamai, Sonic • State • WS-Address W3C • WS-BaseFaults • WS-Resource • WS-Topics • WS-ServiceGroup • Stateful Resource Patterns • WS-Resource Lifetime • WS-BaseNotification • WS-BrokeredNotification • WS-PubSub • SIRI aims to be WS-PubSub enabled • Similar concepts, terminology and separation of concerns • SIRI V1 does not attempt a SOAP WSDL encoding / binding

  21. Subscription Management • Roles “Stateful pattern of interaction” • Subscriber assigns identifier • Notification Producer grants new subscriptions • Subscription manager handles any changes • Notification Producer & Manager know each other • Management Messages • SubscriptionRequest • SubscriptionIdentifier • SubscriptionResponse • Granted or refused • TerminateSubscriptionRequest

  22. Delivery - Direct & Fetched

  23. Mediation • Filtering of Data & Notifications to Reduce data traffic • Incremental Data Changes: • Only send data changes since last update • Change threshold • Only notify if change is more than a certain amount • Grouping of subscriptions • One notification for changes to many subscriptions in a group

  24. Mediation • Interaction of simple patterns can be quite complex.

  25. Use of Interaction Patterns

  26. SIRI Functional Services

  27. PT Systems & SIRI Interfaces a a Generic model of PT operations, showing exchange points for RTI

  28. SIRI Timetable Servcies • Production Timetable • Distribute latest timetable • Schedule to AVMS • AVMS to client • Estimated Timeable • Distribute latest timetable including real-time • Cancellations, additions, short working • Realtime-predictions

  29. SIRI Stop Services • Stop Timetable • Distribute latest timetable • Stop Centric Timetable • Provisions Clients. • Stop Monitoring • Real time Arrival & Departure Boards • Arrivals, Departures, passthroughs

  30. SIRI Connection Services • Connection Timetable • Distribute planned interchanges • Stop Centric • Provisions Clients. • Connection Monitoring • Connection management • Guranteed connection support

  31. SIRI General Message Services • General Message • Exchange structured messages • Simple or embedded structures

  32. SIRI Further Technical Points

  33. SIRI Data Models • TransModel based; Small Subset • Common Concepts& Elements • Participants (Systems) • StopPoints (Pluggable to national systems) • Lines, Directions • Journeys, • VehicleJourneys & Calls • DatedVehicleJourneys & Calls • MonitoredVehcielJourneys & Calls • ConnectingJourneys • Features • Service • Vehicle • Product • Common Structures • Isomorphic optimisations of TransModel for use in interface

  34. Acceptable Optimisations =TransModel Isomorphic? F A A A * 1 1 * Bs * Compression Bs 1 * G B G B G 1 1 1 Cs Cs Cs * * * * C C X(C+D+E) * 1 1 1 D E D 1 E OK NOT OK Compounding

  35. SIRI Functional Requests

  36. SIRI Subscription Requests

  37. SIRI Common Request Structure

  38. Subscription Response

  39. Response Status

  40. Siri Delivery

  41. Example Delivery for Stop Monitoring Common Delivery Structure

  42. Recovery & Restart • Subscriber is responsible for recreating subscriptions on restart, • Consumer is responsible for Detecting Loss • Check Status • Heartbeat • Consumer must know Subscriber!

  43. Detecting a Loss of Service – Check Status

  44. Detecting a Loss of Service - Heartbeat

  45. Extensions • Access Control • Well defined Capabilities • Request based Checking • Discovery • Capability • Coverage • Stops • Lines • Product, Service, Vehicle - Features /Attributes ?

  46. Access Controls • Optional Capability on Requests • By ParticipantCode • Configuration Matrix • Restrict By • By Function &/or Capability (Static) • E.g. Stop Events, Vehicle Movements • E.g. Subscribe, detail level • By Topic (Dynamic) • E.g. Certain Stops, Certain Lines • By Resource level (Dynamic)

  47. Discovery

  48. Stop Points Delivery

  49. Discovering Capabilities

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