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Protocol Design

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Qifan Lu edited this page Sep 13, 2017 · 2 revisions

Protocol Design

u-RPC Data Types

u-RPC currently supports following data types:

  • 0x00: Signed 8-bit data
  • 0x01: Unsigned 8-bit data
  • 0x02: Signed 16-bit data
  • 0x03: Unsigned 16-bit data
  • 0x04: Signed 32-bit data
  • 0x05: Unsigned 32-bit data
  • 0x06: Signed 64-bit data
  • 0x07: Unsigned 64-bit data
  • 0x08: Variable length data
    • The variable length data is represented by prepending a 2-byte length of the data before the data itself when serialized.

u-RPC Signature

u-RPC signature represents the amount and the types of RPC arguments and return values. It consists of a 1-byte number of arguments and the types of arguments.

For example, for function f with type (uint8_t, uint16_t) -> int16_t, the signature of the arguements will be \x02\x01\x03 and the signature of the results will be \x01\x02.

u-RPC Message Types

  • 0x00: Error Response Message
    The error response message is used for indicating that a corresponding request has failed.
  • 0x01: Function Query Message
    The function query message is used for querying the handle of a remote function.
  • 0x02: Function Query Response Message
    The function query response message is used for replying a function query and contains the 16-bit handle for the corresponding function name.
  • 0x03: Function Call Message
    The function call message is used for issuing a remote procedure call.
  • 0x04: Function Call Result Message
    The function call result message is used for replying the function call message and contains call results.

u-RPC Message Formats

  • Message Header (Common for all types of messages)
    • 4-bit magic: 0b1010 (10)
    • 4-bit protocol version (Currently 1)
    • 2-byte message ID
  • 0x00: Error Response Message
    • 2-byte request message ID
    • 1-byte error code
  • 0x01: Function Query Message
    • 1-byte function name length
    • Function name
  • 0x02: Function Query Response Message
    • 2-byte request message ID
    • 2-byte function handle
  • 0x03: Function Call Message
    • 2-byte function handle
    • Signature of arguments
    • Arguments
  • 0x04: Function Call Result Message
    • 2-byte request message ID
    • Signature of results
    • Results
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