Implementation details
The Traffic TPEG API is implemented according to the guidelines found in the Implementation Alternative-2 (Annex B) in TPEG over HTTP specification.
Supported TPEG applications
- TEC (Traffic Event Compact). For details, see "Intelligent transport systems - Traffic and Travel Information (TTI) via Transport Protocol Experts Group, Generation 2 (TPEG2) - Part 15: Traffic Event Compact (TPEG2-TEC_3.2/002)".
- TFP (Traffic Flow and Prediction). Real time traffic flow as FlowMatrix. For details, see "Intelligent transport systems (ITS) - Traffic and Travel Information (TTI) via Transport Protocol Experts Group, Generation 2 (TPEG2) – Part 18: Traffic Flow and Prediction application (TPEG2-TFP_1.0/003)".
Traffic TPEG API allows an application to use different IP addresses for initsession
and getmessages
requests.
For example, an OEM application could send an initsession
request, and the in-car system could send further getmessages
requests.
Supported location referencing
Selection between the following supported location referencing methods is based on traffic content, application type, and preference.
- TMC - Traffic Message Channel location referencing. For details, see ISO 14819-1:2013 "Intelligent transport systems -- Traffic and travel information messages via traffic message coding -- Part 1: Coding protocol for Radio Data System -- Traffic Message Channel (RDS-TMC) using ALERT-C".
- ETL - Extended TMC Locations referencing. For details, see "Intelligent transport systems (ITS) - Traffic and Travel Information (TTI) via Transport Protocol Experts Group, Generation 2 (TPEG2) – Part 20: Extended TMC Locations for applications (TPEG2-ETL_1.0/001)".
- OLR - OpenLR Location Referencing. For details, see "Intelligent Transport Systems (ITS) — Traffic and Travel Information (TTI) via Transport Protocol Experts Group, Generation 2 (TPEG2) - Part 22: OpenLR location reference (TPEG2-OLR_1.0/002)".
Combinations of different Loc-Ref types
- ETL/TMC - ETL will be returned only in case of extended TMC info is available
- XYLR - used for coding locations which are not TMC covered, but is supported only by internal implementation
TPEG2 toolkits
The Message Management Container (MMC) is used by all TPEG applications to provide information about the handling of messages on the TPEG client side. MMC Implementation supports Monolithic Message Management. Multipart Message Management is not supported. See "Intelligent transport systems (ITS) - Traffic and Travel Information (TTI) via Transport Protocol Experts Group, Generation 2 (TPEG2) – Part 6: Message Management Container (TPEG2-MMC_1.1/001)".
Session characteristics
TPEG-over-HTTP implementation alternative 2 uses sessions to identify applications. Session information is created by an InitSession
request, then included in GetMessages
requests.
Sessions are identified by the getmessages
cfg
parameter, which can be used instead of the Session ID.