python/greeter/functions.py

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import json

from statefun import *
import asyncio
from aiohttp import web

functions = StatefulFunctions()

GREET_REQUEST_TYPE = make_json_type(typename="example/GreetRequest")
EGRESS_RECORD_TYPE = make_json_type(typename="io.statefun.playground/EgressRecord")

@functions.bind(typename="example/person", specs=[ValueSpec(name="visits", type=IntType)])
async def person(context: Context, message: Message):
    # update the visit count.
    visits = context.storage.visits or 0
    visits += 1
    context.storage.visits = visits

    # enrich the request with the number of vists.
    request = message.as_type(GREET_REQUEST_TYPE)
    request['visits'] = visits

    # next, we will forward a message to a special greeter function,
    # that will compute a super-doper-personalized greeting based on the
    # number of visits that this person has.
    context.send(
        message_builder(target_typename="example/greeter",
                        target_id=request['name'],
                        value=request,
                        value_type=GREET_REQUEST_TYPE))


@functions.bind(typename="example/greeter")
async def greeter(context, message):
    request = message.as_type(GREET_REQUEST_TYPE)
    person_name = request['name']
    visits = request['visits']

    greeting = await compute_fancy_greeting(person_name, visits)

    egress_record = {
        "topic": "greetings",
        "payload": greeting
    }

    context.send_egress(egress_message_builder(target_typename="io.statefun.playground/egress",
                                             value=egress_record,
                                             value_type=EGRESS_RECORD_TYPE))


async def compute_fancy_greeting(name: str, seen: int):
    """
    Compute a personalized greeting, based on the number of times this @name had been seen before.
    """
    templates = ["", "Welcome %s", "Nice to see you again %s", "Third time is a charm %s"]
    if seen < len(templates):
        greeting = templates[seen] % name
    else:
        greeting = f"Nice to see you at the {seen}-nth time {name}!"

    await asyncio.sleep(1)
    return greeting


#
# Serve the endpoint
#


handler = RequestReplyHandler(functions)


async def handle(request):
    req = await request.read()
    res = await handler.handle_async(req)
    return web.Response(body=res, content_type="application/octet-stream")


app = web.Application()
app.add_routes([web.post('/statefun', handle)])

if __name__ == '__main__':
    web.run_app(app, port=8000)