Send message to parent (#7522)

Extension of host configuration endpoint - setting to enable/disable custom string messages from app to host

frontend/app/src/App.test.tsx

@@ -45,6 +45,7 @@ import {
   PageInfo,
   PageNotFound,
   PagesChanged,
+  ParentMessage,
   mockTheme,
   HOST_COMM_VERSION,
 } from "@streamlit/lib"
@@ -1735,4 +1736,37 @@ describe("handles HostCommunication messaging", () => {
 
     expect(wrapper.find("DeployButton")).toHaveLength(0)
   })
+
+  it("does not relay custom parent messages by default", () => {
+    const logErrorSpy = jest
+      .spyOn(global.console, "error")
+      .mockImplementation(() => {})
+
+    const msg = new ForwardMsg()
+    msg.parentMessage = new ParentMessage({ message: "random string" })
+    instance.handleMessage(msg)
+
+    expect(logErrorSpy).toHaveBeenCalled()
+    expect(logErrorSpy.mock.calls[0][0]).toEqual(
+      "Sending messages to the host is disabled in line with the platform policy."
+    )
+  })
+
+  it("relays custom parent messages when enabled", () => {
+    instance.setState({ appConfig: { enableCustomParentMessages: true } })
+    const sendMessageFunc = jest.spyOn(
+      // @ts-expect-error
+      instance.hostCommunicationMgr,
+      "sendMessageToHost"
+    )
+
+    const msg = new ForwardMsg()
+    msg.parentMessage = new ParentMessage({ message: "random string" })
+    instance.handleMessage(msg)
+
+    expect(sendMessageFunc).toHaveBeenCalledWith({
+      type: "CUSTOM_PARENT_MESSAGE",
+      message: "random string",
+    })
+  })
 })

frontend/app/src/App.tsx

@@ -92,6 +92,7 @@ import {
   PageNotFound,
   PageProfile,
   PagesChanged,
+  ParentMessage,
   SessionEvent,
   SessionStatus,
   WidgetStates,
@@ -386,8 +387,16 @@ export class App extends PureComponent<Props, State> {
       claimHostAuthToken: this.hostCommunicationMgr.claimAuthToken,
       resetHostAuthToken: this.hostCommunicationMgr.resetAuthToken,
       onHostConfigResp: (response: IHostConfigResponse) => {
-        const { allowedOrigins, useExternalAuthToken } = response
-        const appConfig: AppConfig = { allowedOrigins, useExternalAuthToken }
+        const {
+          allowedOrigins,
+          useExternalAuthToken,
+          enableCustomParentMessages,
+        } = response
+        const appConfig: AppConfig = {
+          allowedOrigins,
+          useExternalAuthToken,
+          enableCustomParentMessages,
+        }
         const libConfig: LibConfig = {} // TODO(lukasmasuch): We don't have any libConfig yet:
 
         // Set the allowed origins configuration for the host communication:
@@ -552,6 +561,19 @@ export class App extends PureComponent<Props, State> {
     })
   }
 
+  handleCustomParentMessage = (parentMessage: ParentMessage): void => {
+    if (this.state.appConfig.enableCustomParentMessages) {
+      this.hostCommunicationMgr.sendMessageToHost({
+        type: "CUSTOM_PARENT_MESSAGE",
+        message: parentMessage.message,
+      })
+    } else {
+      logError(
+        "Sending messages to the host is disabled in line with the platform policy."
+      )
+    }
+  }
+
   /**
    * Callback when we get a message from the server.
    */
@@ -595,6 +617,8 @@ export class App extends PureComponent<Props, State> {
           this.handlePageProfileMsg(pageProfile),
         fileUrlsResponse: (fileURLsResponse: FileURLsResponse) =>
           this.uploadClient.onFileURLsResponse(fileURLsResponse),
+        parentMessage: (parentMessage: ParentMessage) =>
+          this.handleCustomParentMessage(parentMessage),
       })
     } catch (e) {
       const err = ensureError(e)

frontend/lib/src/hostComm/types.ts

@@ -156,6 +156,10 @@ export type IGuestToHostMessage =
       type: "SCRIPT_RUN_STATE_CHANGED"
       scriptRunState: ScriptRunState
     }
+  | {
+      type: "CUSTOM_PARENT_MESSAGE"
+      message: string
+    }
 
 export type VersionedMessage<Message> = {
   stCommVersion: number
@@ -183,6 +187,10 @@ export type AppConfig = {
    * with the Streamlit server.
    */
   useExternalAuthToken?: boolean
+  /**
+   * Enables custom string messages to be sent to the host
+   */
+  enableCustomParentMessages?: boolean
 }
 
 /**

lib/streamlit/platform.py

@@ -0,0 +1,31 @@
+# Copyright (c) Streamlit Inc. (2018-2022) Snowflake Inc. (2022)
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Platform module."""
+
+from streamlit.proto.ForwardMsg_pb2 import ForwardMsg
+from streamlit.runtime.scriptrunner import get_script_run_ctx
+
+
+def post_parent_message(message: str) -> None:
+    """
+    Sends a string message to the parent window (when host configuration allows).
+    """
+    ctx = get_script_run_ctx()
+    if ctx is None:
+        return
+
+    fwd_msg = ForwardMsg()
+    fwd_msg.parent_message.message = message
+    ctx.enqueue(fwd_msg)

lib/streamlit/web/server/routes.py

@@ -202,6 +202,8 @@ async def get(self) -> None:
             {
                 "allowedOrigins": self._allowed_origins,
                 "useExternalAuthToken": False,
+                # Default host configuration settings.
+                "enableCustomParentMessages": False,
             }
         )
         self.set_status(200)

lib/tests/streamlit/platform_test.py

@@ -0,0 +1,28 @@
+# Copyright (c) Streamlit Inc. (2018-2022) Snowflake Inc. (2022)
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from parameterized import parameterized
+
+from streamlit.platform import post_parent_message
+from tests.delta_generator_test_case import DeltaGeneratorTestCase
+
+
+class PlatformTest(DeltaGeneratorTestCase):
+    """Tests the platform module functions"""
+
+    @parameterized.expand(["Hello", '{"name":"foo", "type":"bar"}'])
+    def test_post_parent_message(self, message: str):
+        post_parent_message(message)
+        c = self.get_message_from_queue().parent_message
+        self.assertEqual(c.message, message)

lib/tests/streamlit/web/server/routes_test.py

@@ -191,6 +191,8 @@ def test_allowed_message_origins(self):
             {
                 "allowedOrigins": _DEFAULT_ALLOWED_MESSAGE_ORIGINS,
                 "useExternalAuthToken": False,
+                # Default host configuration settings:
+                "enableCustomParentMessages": False,
             },
             response_body,
         )

proto/streamlit/proto/ForwardMsg.proto

@@ -25,6 +25,7 @@ import "streamlit/proto/PageInfo.proto";
 import "streamlit/proto/PageProfile.proto";
 import "streamlit/proto/PageNotFound.proto";
 import "streamlit/proto/PagesChanged.proto";
+import "streamlit/proto/ParentMessage.proto";
 import "streamlit/proto/SessionEvent.proto";
 import "streamlit/proto/SessionStatus.proto";
 
@@ -68,6 +69,9 @@ message ForwardMsg {
     PagesChanged pages_changed = 16;
     FileURLsResponse file_urls_response = 19;
 
+    // Platform - message to host
+    ParentMessage parent_message = 20;
+
     // A reference to a ForwardMsg that has already been delivered.
     // The client should substitute the message with the given hash
     // for this one. If the client does not have the referenced message
@@ -81,7 +85,7 @@ message ForwardMsg {
   string debug_last_backmsg_id = 17;
 
   reserved 7, 8;
-  // Next: 20
+  // Next: 21
 }
 
 // ForwardMsgMetadata contains all data that does _not_ get hashed (or cached)

proto/streamlit/proto/ParentMessage.proto

@@ -0,0 +1,22 @@
+/**!
+ * Copyright (c) Streamlit Inc. (2018-2022) Snowflake Inc. (2022)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+syntax = "proto3";
+
+message ParentMessage {
+  // Message to send to the host.
+  string message = 1;
+}