add polling transport option (#5955)

* add polling transport option

* fix CORS

* set number of workers to 1

* add enterprise guard

* add once why not

Author: adhami3310

reflex/.templates/web/utils/state.js

@@ -854,7 +854,7 @@ export const useEventLoop = (
       await connect(
         socket,
         dispatch,
-        ["websocket"],
+        [env.TRANSPORT],
         setConnectErrors,
         client_storage,
         navigate,

reflex/app.py

@@ -529,22 +529,40 @@ def _setup_state(self) -> None:
 
         # Set up the Socket.IO AsyncServer.
         if not self.sio:
+            if (
+                config.transport == "polling"
+                and (tier := prerequisites.get_user_tier()) != "enterprise"
+            ):
+                console.error(
+                    "The 'polling' transport is only available for Enterprise users. "
+                    + (
+                        "Please upgrade your plan to use this feature."
+                        if tier != "anonymous"
+                        else "Please log in with `reflex login` to use this feature."
+                    )
+                )
+                raise SystemExit(1)
             self.sio = AsyncServer(
                 async_mode="asgi",
                 cors_allowed_origins=(
-                    "*"
-                    if config.cors_allowed_origins == ("*",)
-                    else list(config.cors_allowed_origins)
+                    (
+                        "*"
+                        if config.cors_allowed_origins == ("*",)
+                        else list(config.cors_allowed_origins)
+                    )
+                    if config.transport == "websocket"
+                    else []
                 ),
-                cors_credentials=True,
+                cors_credentials=config.transport == "websocket",
                 max_http_buffer_size=environment.REFLEX_SOCKET_MAX_HTTP_BUFFER_SIZE.get(),
                 ping_interval=environment.REFLEX_SOCKET_INTERVAL.get(),
                 ping_timeout=environment.REFLEX_SOCKET_TIMEOUT.get(),
                 json=SimpleNamespace(
                     dumps=staticmethod(format.json_dumps),
                     loads=staticmethod(json.loads),
                 ),
-                transports=["websocket"],
+                allow_upgrades=False,
+                transports=[config.transport],
             )
         elif getattr(self.sio, "async_mode", "") != "asgi":
             msg = f"Custom `sio` must use `async_mode='asgi'`, not '{self.sio.async_mode}'."

reflex/config.py

@@ -10,7 +10,7 @@
 from importlib.util import find_spec
 from pathlib import Path
 from types import ModuleType
-from typing import TYPE_CHECKING, Any, ClassVar
+from typing import TYPE_CHECKING, Any, ClassVar, Literal
 
 from reflex import constants
 from reflex.constants.base import LogLevel
@@ -254,6 +254,9 @@ class BaseConfig:
     # List of fully qualified import paths of plugins to disable in the app (e.g. reflex.plugins.sitemap.SitemapPlugin).
     disable_plugins: list[str] = dataclasses.field(default_factory=list)
 
+    # The transport method for client-server communication.
+    transport: Literal["websocket", "polling"] = "websocket"
+
     # Whether to skip plugin checks.
     _skip_plugins_checks: bool = dataclasses.field(default=False, repr=False)
 

reflex/utils/build.py

@@ -20,6 +20,7 @@ def set_env_json():
         str(prerequisites.get_web_dir() / constants.Dirs.ENV_JSON),
         {
             **{endpoint.name: endpoint.get_url() for endpoint in constants.Endpoint},
+            "TRANSPORT": get_config().transport,
             "TEST_MODE": is_in_app_harness(),
         },
     )

reflex/utils/prerequisites.py

@@ -674,6 +674,7 @@ def check_schema_up_to_date():
                 )
 
 
+@once
 def get_user_tier():
     """Get the current user's tier.
 

reflex/utils/processes.py

@@ -19,6 +19,7 @@
 from rich.progress import Progress
 
 from reflex import constants
+from reflex.config import get_config
 from reflex.environment import environment
 from reflex.utils import console, path_ops, prerequisites
 from reflex.utils.registry import get_npm_registry
@@ -42,6 +43,9 @@ def get_num_workers() -> int:
     Returns:
         The number of backend worker processes.
     """
+    if get_config().transport == "polling":
+        return 1
+
     if (redis_client := prerequisites.get_redis_sync()) is None:
         return 1