pingpong_nativemessaging_test.py

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#!/usr/bin/env python3

import json

import struct

import sys

# Read a message from stdin and decode it.

def getMessage():

    rawLength = sys.stdin.buffer.read(4)

    if len(rawLength) == 0:

        sys.exit(0)

    messageLength = struct.unpack("@I", rawLength)[0]

    message = sys.stdin.buffer.read(messageLength).decode("utf-8")

    return json.loads(message)

# Encode a message for transmission, given its content.

def encodeMessage(messageContent):

    encodedContent = json.dumps(messageContent, separators=(",", ":")).encode("utf-8")

    encodedLength = struct.pack("@I", len(encodedContent))

    return {"length": encodedLength, "content": encodedContent}

# Send an encoded message to stdout

def sendMessage(encodedMessage):

    sys.stdout.buffer.write(encodedMessage["length"])

    sys.stdout.buffer.write(encodedMessage["content"])

    sys.stdout.buffer.flush()

while True:

    receivedMessage = getMessage()

    if receivedMessage == "ping":

        sendMessage(encodeMessage("native app sends pong"))