1. SDP 2.0 System Data Protocol

2. Overview What is SDP? Provider/Subscriber Pattern SDP Components– Part 1 SDP Simple Usage SDP Messaging SDP Components– Part 2 SDP Messaging

3. What is SDP? System Data Protocol (SDP) is a bidirectional message protocol for transmitting dynamic data. SDP uses a subscription mechanism allowing the right data to be sent at the right time (reduces bandwith). SDP messaging allows many-to-many (peer to peer) communication.

4. Provider/Subscriber Pattern The provider/subscriber pattern defines a one-to- many, unidirectional flow of information. The provider has information or events that need to be communicated to other objects, its subscribers. Provider Subscriber

5. SDP Components – Part 1 SDP Provider SDP Subscriber

6. SDP Provider The SDP Provider waits for subscribe messages. Once a subscription has been accepted, the provider starts sending data messages to its client. When the client no longer requires the data it sends an unsubscribe message, the provider stops sending data messages. SDP Provider subscribe/unsubscribe/request/query data/acknowledge/revoke/provide

7. SDP Subscriber The SDP subscriber sends out subcribe messages when it requires data of a specific type (each data type has a unique ID). The SDP subscriber consumes (uses) the arriving data. SDP Subscriber subscribe/unsubscribe/request/query data/acknowledge/revoke/provide

8. SDP Simple Usage Provider subscribe/unsubscribe/request/query data/acknowledge/revoke/provide Subscriber

9. SDP Message Types Subscriber Messages subscribe = 0 unsubscribe = 1 request-data = 2 provide-query = 3 Provider Messages acknowledge = 4 revoke = 5 data = 6 provide = 7 (range 0-7 requires 3 bits of information, this is the first part of the SDP message header)

10. Packed / Unpacked Messages For increased efficiency, two different message strategies are allowed between SDP components: – Unpacked Messages (objects): Send objects around (pointer to struct containing data fields). Used internally within the same executable. – Packed Messages (serialized data): Send byte arrays containing a serialized version of the message. Used between executables (network, data links etc.)

11. Messaging Example - SDP on CAN Only a single CAN frame is required for transmitting data values up to 32 bits in length (uint8, uint16, uint32). Using ISO-TP as the default CAN transport protocol allows data values up to 4095 bytes to be sent. Byte 1Byte 2Byte 3Byte 4Byte 5Byte 6Byte 7Byte 8 ISO-TP header (1 byte): Single Frame (SF), data-length= 7 SDP header (3 bytes): message-type = data, data-ID = 0x0101 Data Value (4 bytes): uint32 value = 0x1234

12. SDP Components – Part 2 SDP Gateway SDP Router

13. SDP Gateway An SDP gateway routes data between an SDP network and some other data format and/or network. A gateway (usually) has both a provider and subscriber sub-component (as seen below). other data format or network Subscriber Provider SDP Gateway subscribe/unsubscribe/request/query data/acknowledge/revoke/provide

14. SDP Gateway – Examples ISO-TP transmit/recv Subscriber Provider SDP Gateway CAN Bus GX Engine HFAL* Subscriber Provider SDP Gateway Graphics Engine CAN signal read/write Subscriber Provider SDP Gateway signal read/write Subscriber Provider SDP Gateway RTE socket send/recv Subscriber Provider SDP Gateway TCP/IP Subscriber Provider SDP Gateway Serial Link Serial Link send/recv *) HFAL: HMI Framework Adaptation Layer

15. SDP Gateway - Benefits Each gateway can be designed, implemented and tested in isolation. Standardized communication method in one end (SDP messaging). High reusability: gateways can be connected in many different configurations. Follows the Unix philosphy: ”Do one one thing and do it well.”

16. SDP Router Providers, subscribers and gateways can be connected together to form networks. The SDP router allows SDP messages to flow between SDP components with low latency. Routing tables are by default dynamically maintained (just plug in your components). Subscriber Provider SDP Router Subscriber Provider Subscriber Provider... Provider Subscriber other data format Subscriber Provider Gateway

17. Example Network 1 Subscriber Gateway Router Provider Subscriber Gateway Router CAN Bus Application Software 1 (ECU 1) Application Software 2 (ECU 2)

18. Example Network 2 Gateway Router Gateway Router Serial Link Vehicle Processor Graphics Processor Gateway Graphics Engine Gateway RTE Signals

19. Network 2 without router (optimization) Subscriber Provider signal read/write Gateway RCCL / RTE GX Engine HFAL Subscriber Provider Gateway Graphics Engine serial link send/recv Subscriber Provider Gateway Serial Link Subscriber Provider Gateway serial link send/recv Serial Link Vehicle Processor Graphics Processor