A library for a simple integration of the JSON-RPC 2.0 protocol to a Python application using aiohttp. The motivation is to provide a simple, fast and reliable way to integrate the JSON-RPC 2.0 protocol into your application on the server and/or client side.
The library has only one dependency:
- aiohttp - Async http client/server framework
pip install aiohttp-rpcfrom aiohttp import web
import aiohttp_rpc
def echo(*args, **kwargs):
return {
'args': args,
'kwargs': kwargs,
}
# If the function has rpc_request in arguments, then it is automatically passed
async def ping(rpc_request):
return 'pong'
if __name__ == '__main__':
aiohttp_rpc.rpc_server.add_methods([
ping,
echo,
])
app = web.Application()
app.router.add_routes([
web.post('/rpc', aiohttp_rpc.rpc_server.handle_http_request),
])
web.run_app(app, host='0.0.0.0', port=8080)import aiohttp_rpc
import asyncio
async def run():
async with aiohttp_rpc.JsonRpcClient('http://0.0.0.0:8080/rpc') as rpc:
print('#1', await rpc.ping())
print('#2', await rpc.echo('one', 'two'))
print('#3', await rpc.call('echo', three='3'))
print('#4', await rpc.notify('echo', 123))
print('#5', await rpc.get_methods())
print('#6', await rpc.batch([
['echo', 2],
'echo2',
'ping',
]))
loop = asyncio.get_event_loop()
loop.run_until_complete(run())This prints:
#1 pong
#2 {'args': ['one', 'two'], 'kwargs': {}}
#3 {'args': [], 'kwargs': {'three': '3'}}
#4 None
#5 {'get_method': {'doc': None, 'args': ['name'], 'kwargs': []}, 'get_methods': {'doc': None, 'args': [], 'kwargs': []}, 'ping': {'doc': None, 'args': ['rpc_request'], 'kwargs': []}, 'echo': {'doc': None, 'args': [], 'kwargs': []}}
#6 ({'args': [2], 'kwargs': {}}, JsonRpcError(-32601, 'The method does not exist / is not available.'), 'pong')
↑ This is enough to start 😎 ↑
The purpose of this library is to simplify life, and not vice versa. And so, when you start adding existing functions, some problems may arise.
Existing functions can return objects that are not serialized, but this is easy to fix.
You can write own json_serialize:
from aiohttp import web
import aiohttp_rpc
import uuid
import json
from dataclasses import dataclass
from functools import partial
@dataclass
class User: # The object that is not serializable.
uuid: uuid.UUID
username: str = 'mike'
email: str = 'some@mail.com'
async def get_user_by_uuid(user_uuid) -> User:
# Some function which returns not serializable object.
# For example, data may be taken from a database.
return User(uuid=uuid.UUID(user_uuid))
def json_serialize_unknown_value(value):
if isinstance(value, User):
return {
'uuid': str(value.uuid),
'username': value.username,
'email': value.email,
}
return repr(value)
if __name__ == '__main__':
rpc_server = aiohttp_rpc.JsonRpcServer(
json_serialize=partial(json.dumps, default=json_serialize_unknown_value),
)
rpc_server.add_method(get_user_by_uuid)
app = web.Application()
app.router.add_routes([
web.post('/rpc', rpc_server.handle_http_request),
])
web.run_app(app, host='0.0.0.0', port=8080)
...
"""
Example of response:
{
"id": 1,
"jsonrpc": "2.0",
"result": {
"uuid": "600d57b3-dda8-43d0-af79-3e81dbb344fa",
"username": "mike",
"email": "some@mail.com"
}
}
"""But you can go further. If you want to use functions that accept custom types, then you can do something like this:
# The function (RPC method) that takes a custom type.
def generate_user_token(user: User):
return f'token-{str(user.uuid).split("-")[0]}'
async def replace_type(data):
if not isinstance(data, dict) or '__type__' not in data:
return data
if data['__type__'] == 'user':
return await get_user_by_uuid(data['uuid'])
raise aiohttp_rpc.errors.InvalidParams
# The middleware that converts types
async def type_conversion_middleware(request, handler):
request.set_args_and_kwargs(
args=[await replace_type(arg) for arg in request.args],
kwargs={key: await replace_type(value) for key, value in request.kwargs.items()},
)
return await handler(request)
rpc_server = aiohttp_rpc.JsonRpcServer(middlewares=[
aiohttp_rpc.middlewares.exception_middleware,
aiohttp_rpc.middlewares.extra_args_middleware,
type_conversion_middleware,
])
"""
Request:
{
"id": 1234,
"jsonrpc": "2.0",
"method": "generate_user_token",
"params": [{"__type__": "user", "uuid": "600d57b3-dda8-43d0-af79-3e81dbb344fa"}]
}
Response:
{
"id": 1234,
"jsonrpc": "2.0",
"result": "token-600d57b3"
}
"""Middleware allows you to replace arguments, responses, and more.
If you want to add permission checking for each method,
then you can override the class JsonRpcMethod or use middleware.
Middleware is used for RPC Request / RPC Response processing. It has a similar interface as aiohttp middleware.
import aiohttp_rpc
import typing
async def simple_middleware(request: aiohttp_rpc.JsonRpcRequest, handler: typing.Callable) -> aiohttp_rpc.JsonRpcResponse:
# Code to be executed for each RPC request before
# the method (and later middleware) are called.
response = await handler(request)
# Code to be executed for each RPC request / RPC response after
# the method is called.
return response
rpc_server = aiohttp_rpc.JsonRpcServer(middlewares=[
aiohttp_rpc.middlewares.exception_middleware,
simple_middleware,
])Or use aiohttp middlewares to process web.Request/web.Response.
from aiohttp import web
import aiohttp_rpc
async def ping(rpc_request):
return 'pong'
if __name__ == '__main__':
rpc_server = aiohttp_rpc.WsJsonRpcServer(
middlewares=aiohttp_rpc.middlewares.DEFAULT_MIDDLEWARES,
)
rpc_server.add_method(ping)
app = web.Application()
app.router.add_routes([
web.get('/rpc', rpc_server.handle_http_request),
])
app.on_shutdown.append(rpc_server.on_shutdown)
web.run_app(app, host='0.0.0.0', port=8080)import aiohttp_rpc
import asyncio
async def run():
async with aiohttp_rpc.WsJsonRpcClient('http://0.0.0.0:8080/rpc') as rpc:
print(await rpc.ping())
print(await rpc.notify('ping'))
print(await rpc.batch([
['echo', 2],
'echo2',
'ping',
]))
loop = asyncio.get_event_loop()
loop.run_until_complete(run())-
class JsonRpcServer(BaseJsonRpcServer)def __init__(self, *, json_serialize=json_serialize, middlewares=(), methods=None)def add_method(self, method, *, replace=False) -> JsonRpcMethoddef add_methods(self, methods, replace=False) -> typing.List[JsonRpcMethod]def get_method(self, name) -> Optional[Mapping]def get_methods(self) -> Mapping[str, Mapping]async def handle_http_request(self, http_request: web.Request) -> web.Response
-
class WsJsonRpcServer(BaseJsonRpcServer) -
rpc_server: JsonRpcServer
-
class JsonRpcClient(BaseJsonRpcClient)async def connect(self)async def disconnect(self)async def call(self, method: str, *args, **kwargs)async def notify(self, method: str, *args, **kwargs)async def batch(self, methods])async def batch_notify(self, methods)
-
class WsJsonRpcClient(BaseJsonRpcClient)
-
class JsonRpcRequestid: Union[int, str, None]method: strjsonrpc: strextra_args: MutableMappingcontext: MutableMappingparams: Anyargs: Optional[Sequence]kwargs: Optional[Mapping]is_notification: bool
-
class JsonRpcResponseid: Union[int, str, None]jsonrpc: strresult: Anyerror: Optional[JsonRpcError]context: MutableMapping
-
class JsonRpcMethod(BaseJsonRpcMethod)def __init__(self, func, *, name=None, add_extra_args=True, prepare_result=None)
-
class JsonRpcUnlinkedResults -
class JsonRpcDuplicatedResults
def rpc_method(*, rpc_server=default_rpc_server, name=None, add_extra_args=True)
class JsonRpcError(RuntimeError)class ServerError(JsonRpcError)class ParseError(JsonRpcError)class InvalidRequest(JsonRpcError)class MethodNotFound(JsonRpcError)class InvalidParams(JsonRpcError)class InternalError(JsonRpcError)DEFAULT_KNOWN_ERRORS
async def extra_args_middleware(request, handler)async def exception_middleware(request, handler)DEFAULT_MIDDLEWARES
def json_serialize(*args, **kwargs)
NOTHINGVERSION_2_0
The library allows you to add methods in many ways:
import aiohttp_rpc
def ping_1(rpc_request): return 'pong 1'
def ping_2(rpc_request): return 'pong 2'
def ping_3(rpc_request): return 'pong 3'
rpc_server = aiohttp_rpc.JsonRpcServer()
rpc_server.add_method(ping_1) # 'ping_1'
rpc_server.add_method(aiohttp_rpc.JsonRpcMethod(ping_2)) # 'ping_2'
rpc_server.add_method(aiohttp_rpc.JsonRpcMethod(ping_3, name='third_ping')) # 'third_ping'
rpc_server.add_methods([ping_3]) # 'ping_3'
# Replace method
rpc_server.add_method(ping_1, replace=True) # 'ping_1'
rpc_server.add_methods([ping_1, ping_2], replace=True) # 'ping_1', 'ping_2'Example with built-in functions:
# Server
import aiohttp_rpc
rpc_server = aiohttp_rpc.JsonRpcServer(middlewares=[aiohttp_rpc.middlewares.extra_args_middleware])
rpc_server.add_method(sum)
rpc_server.add_method(aiohttp_rpc.JsonRpcMethod(zip, prepare_result=list))
...
# Client
async with aiohttp_rpc.JsonRpcClient('/rpc') as rpc:
assert await rpc.sum([1, 2, 3]) == 6
assert await rpc.zip(['a', 'b'], [1, 2]) == [['a', 1], ['b', 2]]Example with the decorator:
import aiohttp_rpc
from aiohttp import web
@aiohttp_rpc.rpc_method()
def echo(*args, **kwargs):
return {
'args': args,
'kwargs': kwargs,
}
if __name__ == '__main__':
app = web.Application()
app.router.add_routes([
web.post('/rpc', aiohttp_rpc.rpc_server.handle_http_request),
])
web.run_app(app, host='0.0.0.0', port=8080)It is possible to pass params into aiohttp request via direct_call/direct_batch:
import aiohttp_rpc
jsonrpc_request = aiohttp_rpc.JsonRpcRequest(method_name='test', params={'test_value': 1})
async with aiohttp_rpc.JsonRpcClient('/rpc') as rpc:
await rpc.direct_call(jsonrpc_request, headers={'My-Customer-Header': 'custom value'}, timeout=10)MIT