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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 v3.6c. Topics. Overview Key Points Motivation Underlying standards Specific Functional Services

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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 v3.6c

  2. Topics • Overview • Key Points • Motivation • Underlying standards • Specific Functional Services • Transport & Communications • What do you need to do to Implement Siri? • Roadmap • Some Possible Future Work Items

  3. SIRIOverview

  4. SIRI – Introduction • Real-time Server-to-Server Services for Public Transport • Defines a Service Interface for exchanging real-time information of public transport networks. • Complements an underlying static information model for network and timetable description (TRIDENT,VDV, TransXChange) • Provides information on any change on the timetabled information, from original publication to the actual & predicted transport running times.

  5. Gene Pool

  6. Based on • Underlying Standards • Public Transport Data • TransModel : Terminology, model (isomorphic) • VDV 453, 454, Trident, RTIG-XML • Real systems & experience! • GML, WGS84 • Technology • XML, XSD • WS-Soap, WS-PubSub  Web Service enabled • UML, ISO 24531, RFC • Participants • Germany (VDV453, VDV 454) • France (Trident, TransModel) • UK (RTIG-XML, Trident, TransModel) • Denmark, Sweden, Norway, (PubTrans) • Czechoslovakia

  7. SIRI Key Points • Approach • Defines Functional services (real-time) • Defines an independent communication layer (may be reused elsewhere) • SIRI does not define the underlying object structure and data-model (Stop Points, Lines, Route, etc.) : • Assumed to be TransModel compliant • Practical / Pragmatic • SIRI is a tool box, well designed for an incremental implementation • It is not a Panacea …. • Compromises to accomodate real systems • Includes compromises to facilitate migration

  8. Motivation - Uses of SIRI Services • Rapid growth in real-time info - makes Public Transport more efficient to operate & 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. • E.g. Adherence to schedule • Growth of mobile & internet • On-line, real time data. Roaming! • Ubiquitous embedded computing

  9. Motivation – Linking up • Orchestrating Multiple Actors in federated systems • Passenger information services involving multipleproviders • Connection/interchange information • Stop Point/Station operated by several transport operators • etc. • Services between different operators • Single PT line – several operators • Connection management • Services with othercontentproviders • To provide information to content providers • To get information from content providers

  10. Motivation - Standards • Value to Passenger Transport Executives and Authorities / Operators as Customers • Open, modular 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 • European economies of scale • Lowers costs - creating new markets • Modern, Modular, scaleable architectures • Harnesses open internet standards

  11. The SIRI Specifications • SIRI Documents (Completed 2005) • Technical Standard Part 1: Context and Framework Part 2: Communications Infrastructure Part 3: Functional Service Interfaces • Supporting XML Schema – W3C .XSD • Modular package structure, one per service • Support WSDL /SOAP binding using same xsd schema • Migration path from existing standards • Country Profiles & Guidance Notes

  12. Web Site http://www.siri.org.uk

  13. SIRI Approach & Services • Separation of Concerns • Transport layer is separate • Web Service architecture (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

  14. Support Different Operation Models • The same Interfaces can be used for different operational models

  15. 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 • Central or distributed • Evolvable • Able to implement on different generations of technology • Allow modular, incremental implementation: roadmap

  16. SIRI Functional Services

  17. SIRI Timetable Services • Production Timetable (PT) • Distribute latest timetable • Schedule to AVMS • AVMS to client • Estimated Timetable (ET) • Distribute latest timetable including real-time • Cancellations, additions, short working • Realtime-predictions

  18. SIRI Stop Services • Stop Timetable (ST) • Distribute latest timetable • Stop Centric Timetables • Provisions Clients with latest data. • Stop Monitoring (SM) • Real time Arrival & Departure Boards • Arrivals, Departures, pass-throughs • At stop, onboard, away

  19. SIRI Connection Services • Connection Timetable (CT) • Distribute planned interchanges • Stop Centric • Provisions Clients. • Connection Monitoring (CM) • Connection management • Guaranteed connection support

  20. SIRI General Message Services • General Message (GM) • Exchange Structured Messages • Simple or embedded structures (eg TPEG, Trident etc) • Situation, operational, and general info messages

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

  22. Example 1: Hamburg • Federated Modes & Regions

  23. Example 2: Copenhagen • Integrator

  24. Example: Isle de France • Hybrid

  25. Transport & General Communications

  26. Transport & Communications • 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

  27. SIRI Communications Layer • Common to all Functional Services

  28. Common Communications Services • General Functions Common to all SIRI Service Types • Subscription Management • Recovery & Restart • Access Controls – Who is allowed to access? • Versioning – Allows distributed upgrades • Discovery – Which systems have which data? • Some Capabilities are Optional

  29. Communications Framework Patterns • 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

  30. Interaction 1- Request/Response

  31. Interaction 2- Publish/Subscribe

  32. Delivery - Direct

  33. Delivery - Direct & Fetched

  34. 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

  35. Mediation - Efficiency • Reducing Traffic

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

  37. SIRI What do you need to do to implement SIRI ?

  38. How to Implement SIRI #1 • Select the parts of SIRI you need, • Timetables, Stop Monitoring, etc • Discovery, Access Control • Select your transport protocol (SOAP, HTTP post, XML anything else…) • Select additional Web Service (encryption, authentication, etc.) • Select non-mandatory fields (XSD) • Define any needed extensions • Embeddable any data types

  39. How to Implement SIRI #2 • Agree Local Reference data • Identify partipant « peers » • Line Ids • Stop Point Ids (and Stop Point kind…) • Connections Ids • Supported values (ServiceCategory, ProductCategory, VehicleFeature) • Geospatial Coordinate System

  40. How to Implement SIRI #3 • Agree Local Communication & Mediation Options • Interaction Patterns • Request / Response • Publish / Subscribe • Delivery Pattern • Direct only (or Fetched delivery DE) • Multiple Subscriber Delivery • Transport & Comms • http POST / WSDL • Recovery • Heartbeat for PubSub • Acknowledgement of notifications – or not • Mediation • Simple or multiple subscriber filters, • “Stop VisitNumber”

  41. SIRI Further Roadmap

  42. SIRI – Status • Final Draft Awaiting Vote • Next WG Meeting Feb 6/7 2006 • Possible Work Items • Interoperability / Datex? • Some Services live already!

  43. Possible Additional Work Items • Real-time Facility Changes Service FR • Allows changes to availability of facilities and equipment of stop, vehicle and service to be exchanged in real time . This can be used for example to communicate equipment changes affecting impaired access to PT such as lift or escalator changes. Information is of use to real-time journey-planning and alert services. Should consider interchange aspects. • Situation/Event Structured Incident model UK/FR • Enhance GMS to have preferred structured incident model for describing disruptions to services, model relates to SIRI, Based on TPEG + TransModel • Control Actions Server Interface SE • Service for distributing control actions amongst participants, for example for coordinating management of late services. • Traffic Status / Prioritisation Interface for UTMC UK/DE • Allows real-time public transport management systems to exchange information with road UTMC systems, eg to provide real time delay information a road speed information to the road traffic management system, or to allow for the exchange of signal priority options.

  44. SIRI Data Content Exchange Behaviour Transport Protocol • Mainstream Internet • HTTP POST, • SOAP. defined XML Schema For payload well-defined interactions with XML schema representations XML XML Http Post SOAP http get ? TransModel WS-PubSub IP

  45. DATEX II Data Content Exchange Behaviour Transport Protocol defined XML schema (draft, work in progress) D2 deliverable specifies… may be revised? in progress for 2006 publication HTTP GET, POST, SOAP.

  46. Some Conclusions • TransModel invaluable • Vocabulary & concepts • Tool for harmonisation legacy standards • Message architectures critical for real time efficiency • Based on proven architectures • Modularity for legacy migration • Incremental implementations, optional features • XML allows flexible coupling • Road map for additional features

  47. SIRI Further Technical Points

  48. SIRI XSD Packages – Layered Reuse Low Level Types Common Request Management SIRI Common Model SIRI Functional Services

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

  50. 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

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