Usage Examples

In absence of a complete tutorial, these files can serve as reference implementations for server and client. In order to test them, run ./server.py in one terminal, and use ./clientGET.py and ./clientPUT.py to interact with it.

Unlike the library and its tools, these examples use the modern (Python 3.5 and later) async idiom instead of the original asyncio yield from. This is to align them better with what novice users are expected to learn when introduced to asynchronous programming in Python.

Client

import logging
import asyncio

from aiocoap import *

logging.basicConfig(level=logging.INFO)

async def main():
    protocol = await Context.create_client_context()

    request = Message(code=GET, uri='coap://localhost/time')

    try:
        response = await protocol.request(request).response
    except Exception as e:
        print('Failed to fetch resource:')
        print(e)
    else:
        print('Result: %s\n%r'%(response.code, response.payload))

if __name__ == "__main__":
    asyncio.get_event_loop().run_until_complete(main())

import logging
import asyncio

from aiocoap import *

logging.basicConfig(level=logging.INFO)

async def main():
    """
    Example class which performs single PUT request to localhost
    port 5683 (official IANA assigned CoAP port), URI "/other/block".
    Request is sent 2 seconds after initialization.

    Payload is bigger than 1kB, and thus is sent as several blocks.
    """

    context = await Context.create_client_context()

    await asyncio.sleep(2)

    payload = b"The quick brown fox jumps over the lazy dog.\n" * 30
    request = Message(code=PUT, payload=payload)
    request.opt.uri_host = '127.0.0.1'
    request.opt.uri_path = ("other", "block")

    response = await context.request(request).response

    print('Result: %s\n%r'%(response.code, response.payload))

if __name__ == "__main__":
    asyncio.get_event_loop().run_until_complete(main())

Server

import datetime
import logging

import asyncio

import aiocoap.resource as resource
import aiocoap


class BlockResource(resource.Resource):
    """
    Example resource which supports GET and PUT methods. It sends large
    responses, which trigger blockwise transfer.
    """

    def __init__(self):
        super(BlockResource, self).__init__()
        self.content = ("This is the resource's default content. It is padded "\
                "with numbers to be large enough to trigger blockwise "\
                "transfer.\n" + "0123456789\n" * 100).encode("ascii")

    async def render_get(self, request):
        return aiocoap.Message(payload=self.content)

    async def render_put(self, request):
        print('PUT payload: %s' % request.payload)
        self.content = request.payload
        payload = ("I've accepted the new payload. You may inspect it here in "\
                "Python's repr format:\n\n%r"%self.content).encode('utf8')
        return aiocoap.Message(payload=payload)


class SeparateLargeResource(resource.Resource):
    """
    Example resource which supports GET method. It uses asyncio.sleep to
    simulate a long-running operation, and thus forces the protocol to send
    empty ACK first.
    """

    def __init__(self):
        super(SeparateLargeResource, self).__init__()
#        self.add_param(resource.LinkParam("title", "Large resource."))

    async def render_get(self, request):
        await asyncio.sleep(3)

        payload = "Three rings for the elven kings under the sky, seven rings"\
                "for dwarven lords in their halls of stone, nine rings for"\
                "mortal men doomed to die, one ring for the dark lord on his"\
                "dark throne.".encode('ascii')
        return aiocoap.Message(payload=payload)

class TimeResource(resource.ObservableResource):
    """
    Example resource that can be observed. The `notify` method keeps scheduling
    itself, and calles `update_state` to trigger sending notifications.
    """
    def __init__(self):
        super(TimeResource, self).__init__()

        self.notify()

    def notify(self):
        self.updated_state()
        asyncio.get_event_loop().call_later(6, self.notify)

    def update_observation_count(self, count):
        if count:
            # not that it's actually implemented like that here -- unconditional updating works just as well
            print("Keeping the clock nearby to trigger observations")
        else:
            print("Stowing away the clock until someone asks again")

    async def render_get(self, request):
        payload = datetime.datetime.now().strftime("%Y-%m-%d %H:%M").encode('ascii')
        return aiocoap.Message(payload=payload)

#class CoreResource(resource.Resource):
#    """
#    Example Resource that provides list of links hosted by a server.
#    Normally it should be hosted at /.well-known/core
#
#    Notice that self.visible is not set - that means that resource won't
#    be listed in the link format it hosts.
#    """
#
#    def __init__(self, root):
#        resource.Resource.__init__(self)
#        self.root = root
#
#    async def render_get(self, request):
#        data = []
#        self.root.generate_resource_list(data, "")
#        payload = ",".join(data).encode('utf-8')
#        return aiocoap.Message(payload=payload, content_format=40)

# logging setup

logging.basicConfig(level=logging.INFO)
logging.getLogger("coap-server").setLevel(logging.DEBUG)

def main():
    # Resource tree creation
    root = resource.Site()

    root.add_resource(('.well-known', 'core'), resource.WKCResource(root.get_resources_as_linkheader))

    root.add_resource(('time',), TimeResource())

    root.add_resource(('other', 'block'), BlockResource())

    root.add_resource(('other', 'separate'), SeparateLargeResource())

    asyncio.Task(aiocoap.Context.create_server_context(root))

    asyncio.get_event_loop().run_forever()

if __name__ == "__main__":
    main()