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How a gRPC message uses length-prefixed framing?

2020-05-06

Categories: DevOps Networking

Once we have the encoded data to send to the other end, we need to package the data in a way that other end can easily extract the information. gRPC uses a message framing technique called length-prefixed framing.

Filter gRPC messages:

$ tshark -r grpc.pcapng -Y 'grpc'

Find out a stream: DATA:

216 923.033355    127.0.0.1 → 127.0.0.1    GRPC 108 DATA[1] (GRPC) (PROTOBUF)

and show the packet details:

tshark -r grpc.pcapng -Y "frame.number == 216" -V

HyperText Transfer Protocol 2
    GRPC Message: /book.BookInfo/getBook, Request
        Compressed Flag: Not Compressed (0)
        Message Length: 38
        Message Data: 38 bytes

• first byte: indicate whether data is compressed or not
• next 4 bytes: size of the encoding binary message (38)

Tags: grpc protocol-buffers length-prefixed-framing