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SIRI Framework

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Eliot edited this page Oct 11, 2023 · 13 revisions

SIRI Functional Services

SIRI provides a number of functional services that can be used to exchange public transport information. These services are defined in the SIRI XSD schema.

Service Name Definition
Production Timetable (SIRI-PT) Allows clients to request and receive the timetable for a specific public transport service.
Estimated Timetable (SIRI-ET) Allows clients to request and receive the estimated timetable for a specific public transport service.
Stop Timetable (SIRI-ST) Allows clients to request and receive the timetable for a specific stop.
Stop Monitoring (SIRI-SM) Allows clients to request and receive real-time information about the arrival and departure of vehicles at a specific stop.
Vehicle Monitoring (SIRI-VM) Allows clients to request and receive real-time information about the location and status of vehicles.
Connection Timetable (SIRI-CT) Allows clients to request and receive the timetable for a journey that involves multiple public transport services.
Connection Monitoring (SIRI-CM) Allows clients to request and receive real-time information about the arrival and departure of vehicles at a specific stop that are part of a journey that involves multiple public transport services.
General Message (SIRI-GM) Allows clients to exchange general messages about public transport services.

Benefits of using SIRI functional services

SIRI functional services can be used to develop a wide range of public transport applications. For example, SIRI can be used to develop:

  • Public transport information websites and apps
  • Real-time vehicle tracking systems
  • Passenger information systems
  • Journey planning systems
  • Traffic management systems

Examples of these services can be found here.

SIRI XML model

The SIRI XML model is a set of XML elements and attributes that are used to exchange public transport information. The SIRI XML model is defined in the SIRI XSD schema.

The SIRI XML model includes elements for representing a wide range of public transport data, such as:

  • Vehicles
  • Journeys
  • Stops
  • Lines
  • Services
  • Schedules
  • Real-time information

Here is an example of a simple SIRI XML message:

<?xml version="1.0" encoding="UTF-8"?>
<Siri xmlns="http://www.siri.org.uk/siri">
  <ServiceRequest>
    <VehicleMonitoringRequest>
      <VehicleRef>
        <VehicleID>12345</VehicleID>
      </VehicleRef>
    </VehicleMonitoringRequest>
  </ServiceRequest>
</Siri>

This message is a request for the current location of the vehicle with the ID 12345. The response to this message would be a SIRI XML message containing the vehicle's location information.

<?xml version="1.0" encoding="UTF-8"?>
<Siri xmlns="http://www.siri.org.uk/siri">
  <ServiceDelivery>
    <VehicleMonitoringDelivery>
      <VehicleMonitoringResponse>
        <VehicleActivity>
          <VehicleRef>
            <VehicleID>12345</VehicleID>
          </VehicleRef>
          <Position>
            <Latitude>57.7</Latitude>
            <Longitude>12.1</Longitude>
          </Position>
          <Bearing>0</Bearing>
          <Speed>50</Speed>
        </VehicleActivity>
      </VehicleMonitoringResponse>
    </VehicleMonitoringDelivery>
  </ServiceDelivery>
</Siri>

This response contains the current location of the vehicle with the ID 12345. The vehicle is currently located at latitude 57.7 and longitude 12.1, and it is traveling at a speed of 50 km/h on a bearing of 0 degrees.

This is just a simple example of a SIRI request/response message. The SIRI XML model can be used to exchange a wide variety of public transport data, including journey plans, real-time information, and service disruptions. See more information on the SIRI XML schema or see examples of SIRI services use cases.

Structure LEADER

The description of SIRI services refers to a LEADER structure. It is a container element that is used to exchange SIRI messages between different systems.

The Leader is (indirectly) defined in the SIRI specification by the following attributes

xxxDelivery xxxDelivery Min : Max Data Type Delivery for xxx Service
Log ResponseTimestamp 1:1 xsd:dateTime Time individual response element was created
Endpoint properties RequestMessageRef 0:1 ➡️ MessageQualifier For direct requests, Identifier of request that this Delivery satisfies
Endpoint properties SubscriberRef 0:1 ➡️ ParticipantCode Required if Delivery is for a Subscription, Participant Reference of Subscriber
Endpoint properties SubscriptionFilterRef 0:1 ➡️SubcriptionFilterCode Unique identifier of Subscription filter to which this subscription is assigned. If there is only a single filter, then can be omitted
Endpoint properties SubscriptionRef 1:1 ➡️SubscriptionQualifier Required if Delivery is for a Subscription, Identifier of Subscription issued by Requestor. Unique within Subscriber (i.e. within ParticipantRef of Subscriber), and SIRI Functional Service type.
Delegation DelegatorAddress 0:1 Xsd:anyURI Address of original Consumer, i.e. requesting system to which delegating response is to be returned
Delegation DelegatorRef 0:1 ➡️ ParticipantCode Identifier of delegating system that originated message
Status Status 0:1 xsd:boolean Whether the complete request could be processed successfully or not. Default is true. If any of the individual requests within the delivery failed, should be set to false
Status ErrorCondition 0:1 +Structure Description of any error or warning conditions that apply to the specific functional request or response
Status choice One of the following Error codes
Status a)CapabilityNotSupportedError -1:1 + Error Error: Capability not supported
Status b)AccessNotAllowedError -1:1 + Error Error: Requestor is not authorised to the service or data requested
Status c)NoInfoForTopicError -1:1 + Error Error: Valid request was made but service does not hold any data for the requested topic expression
Status d)AllowedResourceUsageExceededError -1:1 + Error Error: Valid request was made but request would exceed the permitted resource usage of the client
Status e)OtherError -1:1 + Error Error other than a well-defined category.
Status Description 0:1 ➡️ ErrorDescription Description of Error
Status ValidUntil 0:1 xsd:dateTime End of data horizon of the data producer
Status ShortestPossibleCycle 0:1 PositiveDurationType Minimum interval at which updates can be sent
DefaultLanguage 0:1 Xsd:language Default language for text elements

The LEADER structure is used in both SIRI request/response and publish/subscribe communication patterns. In SIRI request/response, the LEADER message is used to return the response to a SIRI service request. In SIRI publish/subscribe, the LEADER message is used to deliver updates to subscribers.

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