fix: async bento client methods (#3152)

* fix: async bento client methods

* format?

* format

* address review comment

src/bentoml/client.py

@@ -1,9 +1,13 @@
 from __future__ import annotations
 
+import json
 import typing as t
+import asyncio
 import functools
 from abc import ABC
 from abc import abstractmethod
+from http.client import HTTPConnection
+from urllib.parse import urlparse
 
 import aiohttp
 import starlette.requests
@@ -27,15 +31,30 @@ def __init__(self, svc: Service, server_url: str):
 
         for name, api in self._svc.apis.items():
             if not hasattr(self, name):
-                setattr(self, name, functools.partial(self._call, _bentoml_api=api))
+                setattr(
+                    self, name, functools.partial(self._sync_call, _bentoml_api=api)
+                )
+
+        for name, api in self._svc.apis.items():
+            if not hasattr(self, f"async_{name}"):
+                setattr(
+                    self,
+                    f"async_{name}",
+                    functools.partial(self._call, _bentoml_api=api),
+                )
 
-    def call(self, api_name: str, inp: t.Any = None, **kwargs: t.Any) -> t.Any:
-        asyncio.run(self.async_call(api_name, inp))
+    def call(self, bentoml_api_name: str, inp: t.Any = None, **kwargs: t.Any) -> t.Any:
+        return asyncio.run(self.async_call(bentoml_api_name, inp))
 
     async def async_call(
-        self, api_name: str, inp: t.Any = None, **kwargs: t.Any
+        self, bentoml_api_name: str, inp: t.Any = None, **kwargs: t.Any
     ) -> t.Any:
-        return self._call(inp, _bentoml_api=self._svc.apis[api_name])
+        return await self._call(inp, _bentoml_api=self._svc.apis[bentoml_api_name])
+
+    def _sync_call(
+        self, inp: t.Any = None, *, _bentoml_api: InferenceAPI, **kwagrs: t.Any
+    ):
+        return asyncio.run(self._call(inp, _bentoml_api=_bentoml_api))
 
     @abstractmethod
     async def _call(
@@ -44,12 +63,16 @@ async def _call(
         raise NotImplementedError
 
     @staticmethod
-    async def from_url(server_url: str) -> Client:
+    def from_url(server_url: str) -> Client:
+        server_url = server_url if "://" in server_url else "http://" + server_url
+        url_parts = urlparse(server_url)
+
         # TODO: SSL and grpc support
-        # connection is passed off to the client, and so is not closed
-        async with aiohttp.ClientSession(server_url) as conn:
-            async with conn.get("/docs.json") as resp:
-                openapi_spec = await resp.json()
+        conn = HTTPConnection(url_parts.netloc)
+        conn.request("GET", "/docs.json")
+        resp = conn.getresponse()
+        openapi_spec = json.load(resp)
+        conn.close()
 
         dummy_service = Service(openapi_spec["info"]["title"])