# Establishing a Data Channel Between the Application and the Frontend Page (C/C++)

The native **PostWebMessage** is provided to implement communication between the frontend page and the application, which reduces unnecessary switching to the ArkTS environment and allows messages and callbacks to be reported in non-UI threads to avoid UI blocking. Currently, only the string and buffer can be sent.

## Applicable Application Architecture

If an application is developed using both ArkTS and C++, or the application architecture is close to the applet architecture and has a built-in C++ environment, you are advised to use [ArkWeb_ControllerAPI](../reference/apis-arkweb/_ark_web___controller_a_p_i.md#arkweb_controllerapi), [ArkWeb_WebMessageAPI](../reference/apis-arkweb/_ark_web___web_message_a_p_i.md#arkweb_webmessageapi) and [ArkWeb_WebMessagePortAPI](../reference/apis-arkweb/_ark_web___web_message_port_a_p_i.md#arkweb_webmessageportapi) provided by ArkWeb on the native side to implement the **PostWebMessage** feature.

  ![arkweb_jsbridge_arch](figures/arkweb_jsbridge_arch.png)

  The preceding figure shows a general architecture of applets with universal applicability. In this architecture, the logical layer depends on a JavaScript runtime built in an application, and the runtime runs in an existing C++ environment. The logic layer can communicate with the view layer (in which ArkWeb as the renderer) in the C++ environment through the native API, instead of using the ArkTS **PostWebMessage** API in the ArkTS environment.

  The figure on the left shows that the application needs to invoke the ArkTS environment and then the C++ environment to build an applet using the ArkTS **PostWebMessage** API. Using the native **PostWebMessage** API is more efficient because the switch between the ArkTS and C++ environments is not required, as shown in the figure on the right.

  ![arkweb_postwebmessage_diff](figures/arkweb_postwebmessage_diff.png)

## Using the Native API to Implement PostWebMessage

### Binding the Native API to ArkWeb

- The ArkWeb component is declared on the ArkTS side. You need to define a **webTag** and pass it to the C++ side of the application through the Node-API. When the ArkWeb native API is called, **webTag** uniquely identifies the corresponding component.

- ArkTS side:

  ```ts
  import { webview } from '@kit.ArkWeb';
  // Define a webTag and pass it to WebviewController when it is created to establish the mapping between controller and webTag.
  webTag: string = 'ArkWeb1';
  controller: webview.WebviewController = new webview.WebviewController(this.webTag);
  ...
  // Use aboutToAppear() to pass webTag to C++ through the Node-API. The webTag uniquely identifies the C++ ArkWeb component.
  aboutToAppear() {
    console.info("aboutToAppear")
    // Initialize the NDK API of the Web component.
    testNapi.nativeWebInit(this.webTag);
  }
  ...
  ```

### Obtaining API Struct Using the Native API

To invoke the native APIs in the API structs, obtain the API structs on the ArkWeb native side first. You can pass different types of parameters in the [OH_ArkWeb_GetNativeAPI](../reference/apis-arkweb/_web.md#oh_arkweb_getnativeapi()) function to obtain the corresponding function pointer structs. The following APIs are provided: [ArkWeb_ControllerAPI](../reference/apis-arkweb/_ark_web___controller_a_p_i.md#arkweb_controllerapi), [ArkWeb_WebMessageAPI](../reference/apis-arkweb/_ark_web___web_message_a_p_i.md#arkweb_webmessageapi) and [ArkWeb_WebMessagePortAPI](../reference/apis-arkweb/_ark_web___web_message_port_a_p_i.md#arkweb_webmessageportapi).

  ```c++
  static ArkWeb_ControllerAPI *controller = nullptr;
  static ArkWeb_WebMessagePortAPI *webMessagePort = nullptr;
  static ArkWeb_WebMessageAPI *webMessage = nullptr;
  ...
  controller = reinterpret_cast<ArkWeb_ControllerAPI *>(OH_ArkWeb_GetNativeAPI(ARKWEB_NATIVE_CONTROLLER));
  webMessagePort =
      reinterpret_cast<ArkWeb_WebMessagePortAPI *>(OH_ArkWeb_GetNativeAPI(ARKWEB_NATIVE_WEB_MESSAGE_PORT));
  webMessage = reinterpret_cast<ArkWeb_WebMessageAPI *>(OH_ArkWeb_GetNativeAPI(ARKWEB_NATIVE_WEB_MESSAGE));
  ```

### Sample Code

Use [ARKWEB_MEMBER_MISSING](../reference/apis-arkweb/_web.md#arkweb_member_missing) to check whether the function struct has the corresponding pointer before calling an API to avoid crash caused by mismatch between the SDK and the device ROM. You must use [createWebMessagePorts](../reference/apis-arkweb/_ark_web___controller_a_p_i.md#createwebmessageports), [postWebMessage](../reference/apis-arkweb/_ark_web___controller_a_p_i.md#postwebmessage) and [close](../reference/apis-arkweb/_ark_web___web_message_port_a_p_i.md#close) in the UI thread.

* Frontend page code:

  ```html
  <!-- entry/src/main/resources/rawfile/index.html -->
  <!-- index.html -->
  <!DOCTYPE html>
  <html lang="en-gb">
  <body>
  <h1>etsRunJavaScriptExt test demo</h1>;
  <h1 id="h1"></h1>
  <h3 id="msg">Receive string:</h3>
  <h3 id="msg2">Receive arraybuffer:</h3>

  </body>
  <script type="text/javascript">
  var h5Port;

  window.addEventListener('message', function (event) {
      if (event.data == 'init_web_messageport') {
          const port = event.ports.at(0); // 1. Save the port sent from the application.
          if (port) {
              console.log("hwd In html got message");
              h5Port = port;
              port.onmessage = function (event) {
                  console.log("hwd In html got message");
                  // 2. Receive the message sent from the application.
                  var result = event.data;
                  var type_s = typeof (result)
                  switch (type_s) {
                      case "object":
                          if (result instanceof ArrayBuffer) {
                              type_s = "ArrayBuffer";
                              var view = new Uint8Array(result);
                              const decoder = new TextDecoder('utf-8');
                              result = decoder.decode(result);
                          } else if (result instanceof Error) {
                              type_s = "Error";
                          } else if (result instanceof Array) {
                              type_s = "Array";
                          }
                          break;
                      default:
                          break;
                  }
                  console.log("H5 recv type: " + type_s + "\nH5 recv result: " + result)
                  document.getElementById("msg").innerHTML = "recv type: " + type_s;
                  document.getElementById("msg2").innerHTML = "recv value: " + result;
              }
              h5Port.onmessageerror = (event) => {
                  console.error(`hwd In html Error receiving message: ${event}`);
              };
          }
      }
  })
  window.onerror = function(message, url, line, column, error) {
    console.log("JavaScript Error: " + message + " on line " + line + " in " + url);
    document.getElementById("h1").innerHTML = "Failed to execute the function."
  };

  // 3. Use h5Port to send messages to the application.
  function postStringToApp() {
      if (h5Port) {
          h5Port.postMessage("send string from H5");
      } else {
          console.error("In html h5port is null, please init first");
      }
  }
  function postBufferToApp() {
      if (h5Port) {
          const str = "Hello, World!";
          const encoder = new TextEncoder();
          const uint8Array = encoder.encode(str);
          h5Port.postMessage(uint8Array.buffer);
      } else {
          console.error("In html h5port is null, please init first");
      }
  }

  function postJsonToApp() {
      if (h5Port) {
          var e = {"json": "json"};
          h5Port.postMessage(e);
      } else {
          console.error("In html h5port is null, please init first");
      }
  }

  function postArrayStringToApp() {
      if (h5Port) {
          h5Port.postMessage(["1", "2", "3"]);
      } else {
          console.error("In html h5port is null, please init first");
      }
  }

  function postNumberToApp() {
      if (h5Port) {
          h5Port.postMessage(123);
      } else {
          console.error("In html h5port is null, please init first");
      }
  }
  class MyClass {
    constructor() {
      // Constructor.
      this.myProperty = 'Hello, World!';
    }

    myMethod() {
      // Instance method.
      console.log(this.myProperty);
    }

    static myStaticMethod() {
      // Static method.
      console.log('This is a static method.');
    }
  }
  function postObjectToApp() {
      if (h5Port) {
          h5Port.postMessage(new MyClass());
      } else {
          console.error("In html h5port is null, please init first");
      }
  }

  </script>
  </html>
  ```

* ArkTS code:

  ```javascript
  // entry/src/main/ets/pages/Index.ets
  import testNapi from 'libentry.so'
  import web_webview from '@ohos.web.webview';
  import { BusinessError } from '@ohos.base';

  @Entry
  @Component
  struct Index {
    @State webTag: string = 'postMessage';
    controller: web_webview.WebviewController = new web_webview.WebviewController(this.webTag);
    @State h5Log: string = 'Display received message send from HTML';

    aboutToAppear() {
      web_webview.WebviewController.setWebDebuggingAccess(true);
      // Initialize the NDK API of the Web component.
      testNapi.nativeWebInit(this.webTag);
    }

    aboutToDisAppear() {
      console.error("aboutToDisAppear")
    }

    build() {
      Scroll() {
        Column({ space: 10 }) {
          // Display the content received by the HTML5 page.
          Text ("The message received by the HTML5 page from the application")
          TextArea({text: this.h5Log})
            .id("log_area")
            .width("100%")
            .height(100)
            .border({ width: 1 })
          Text ("Button on the application")
          Row() {
            Button('createNoControllerTagPort')
              .id("create_no_tag_btn")
              .onClick(() => {
                try {
                  testNapi.createWebMessagePorts("noTag");
                } catch (error) {
                  console.error(`ErrorCode: ${(error as BusinessError).code},  Message: ${(error as BusinessError).message}`);
                }
              })
            Button('createPort')
              .id("create_port_btn")
              .onClick(() => {
                try {
                  testNapi.createWebMessagePorts(this.webTag);
                } catch (error) {
                  console.error(`ErrorCode: ${(error as BusinessError).code},  Message: ${(error as BusinessError).message}`);
                }
              })
          }

          Row({ space: 10 }) {

            Button('setHandler')
              .id("set_handler_btn")
              .onClick(() => {
                try {
                  testNapi.setMessageEventHandler(this.webTag);
                } catch (error) {
                  console.error(`ErrorCode: ${(error as BusinessError).code},  Message: ${(error as BusinessError).message}`);
                }
              })

            Button('setHandlerThread')
              .id("set_handler_thread_btn")
              .onClick(() => {
                try {
                  testNapi.setMessageEventHandlerThread(this.webTag);
                } catch (error) {
                  console.error(`ErrorCode: ${(error as BusinessError).code},  Message: ${(error as BusinessError).message}`);
                }
              })
          }

          Row({ space: 10 }) {
            Button('SendString')
              .id("send_string_btn")
              .onClick(() => {
                try {
                  this.h5Log = ""
                  testNapi.postMessage(this.webTag);
                } catch (error) {
                  console.error(`ErrorCode: ${(error as BusinessError).code},  Message: ${(error as BusinessError).message}`);
                }
              })
            Button('SendStringThread')
              .id("send_string_thread_btn")
              .onClick(() => {
                try {
                  this.h5Log = ""
                  testNapi.postMessageThread(this.webTag);
                } catch (error) {
                  console.error(`ErrorCode: ${(error as BusinessError).code},  Message: ${(error as BusinessError).message}`);
                }
              })
          }

          Row({ space: 10 }) {
            Button('SendBuffer')
              .id("send_buffer_btn")
              .onClick(() => {
                try {
                  this.h5Log = ""
                  testNapi.postBufferMessage(this.webTag);
                } catch (error) {
                  console.error(`ErrorCode: ${(error as BusinessError).code},  Message: ${(error as BusinessError).message}`);
                }
              })
            Button('SendNone')
              .id("send_none_btn")
              .onClick(() => {
                try {
                  this.h5Log = ""
                  testNapi.postNoneMessage(this.webTag);
                } catch (error) {
                  console.error(`ErrorCode: ${(error as BusinessError).code},  Message: ${(error as BusinessError).message}`);
                }
              })
          }

          Row({ space: 10 }) {

            Button('closePort')
              .id("close_port_btn")
              .onClick(() => {
                try {
                  testNapi.closeMessagePort(this.webTag);
                } catch (error) {
                  console.error(`ErrorCode: ${(error as BusinessError).code},  Message: ${(error as BusinessError).message}`);
                }
              })
            Button('destroyNullPort')
              .id("destroy_null_btn")
              .onClick(() => {
                try {
                  testNapi.destroyNullMessagePort(this.webTag);
                } catch (error) {
                  console.error(`ErrorCode: ${(error as BusinessError).code},  Message: ${(error as BusinessError).message}`);
                }
              })
            Button('destroyPort')
              .id("destroy_port_btn")
              .onClick(() => {
                try {
                  testNapi.destroyMessagePort(this.webTag);
                } catch (error) {
                  console.error(`ErrorCode: ${(error as BusinessError).code},  Message: ${(error as BusinessError).message}`);
                }
              })
          }
          .width("100%")
          .padding(10)
          .border({ width: 1 })

          Column({ space: 10 }) {
            Text ("The Send button on the HTML5 page")
            Row({ space: 10 }) {
              Button('H5String')
                .id("h5_send_string_btn")
                .onClick(() => {
                  try {
                    this.controller.runJavaScript("for(var i = 0; i < 2000; i++) postStringToApp()")
                  } catch (error) {
                    console.error(`ErrorCode: ${(error as BusinessError).code},  Message: ${(error as BusinessError).message}`);
                  }
                })
              Button('H5Buffer')
                .id("h5_send_buffer_btn")
                .onClick(() => {
                  try {
                    this.controller.runJavaScript("postBufferToApp()")
                  } catch (error) {
                    console.error(`ErrorCode: ${(error as BusinessError).code},  Message: ${(error as BusinessError).message}`);
                  }
                })
              Button('H5Number')
                .id("h5_send_number_btn")
                .onClick(() => {
                  try {
                    this.controller.runJavaScript("postNumberToApp()")
                  } catch (error) {
                    console.error(`ErrorCode: ${(error as BusinessError).code},  Message: ${(error as BusinessError).message}`);
                  }
                })
            }

            Row({ space: 10 }) {
              Button('H5Json')
                .id("h5_send_json_btn")
                .onClick(() => {
                  try {
                    this.controller.runJavaScript("postJsonToApp()")
                  } catch (error) {
                    console.error(`ErrorCode: ${(error as BusinessError).code},  Message: ${(error as BusinessError).message}`);
                  }
                })
              Button('H5Array')
                .id("h5_send_array_btn")
                .onClick(() => {
                  try {
                    this.controller.runJavaScript("postArrayStringToApp()")
                  } catch (error) {
                    console.error(`ErrorCode: ${(error as BusinessError).code},  Message: ${(error as BusinessError).message}`);
                  }
                })
              Button('H5Object')
                .id("h5_send_object_btn")
                .onClick(() => {
                  try {
                    this.controller.runJavaScript("postObjectToApp()")
                  } catch (error) {
                    console.error(`ErrorCode: ${(error as BusinessError).code},  Message: ${(error as BusinessError).message}`);
                  }
                })
            }
          }
          .width("100%")
          .margin(10)
          .padding(10)
          .border({ width: 1 })

          Web({ src: $rawfile('index.html'), controller: this.controller })
            .onConsole((event) => {
              if (event) {
                let msg = event.message.getMessage()
                if (msg.startsWith("H5")) {
                  this.h5Log = event.message.getMessage() + "\n" + this.h5Log
                }
              }
              return false;
            })
        }
      }.height('100%')
      .scrollable(ScrollDirection.Vertical)
      .scrollBar(BarState.Off)
      .edgeEffect(EdgeEffect.Spring)
    }
  }
  ```

* ArkTS APIs exposed on the Node-API side:

  ```javascript
  // entry/src/main/cpp/types/libentry/index.d.ts
  export const nativeWebInit: (webName: string) => void;
  export const createWebMessagePorts: (webName: string) => void;
  export const postMessage: (webName: string) => void;
  export const postNoneMessage: (webName: string) => void;
  export const setMessageEventHandler: (webName: string) => void;
  export const closeMessagePort: (webName: string) => void;
  export const destroyMessagePort: (webName: string) => void;
  export const postBufferMessage: (webName: string) => void;
  export const destroyNullMessagePort: (webName: string) => void;
  export const setMessageEventHandlerThread: (webName: string) => void;
  export const postMessageThread: (webName: string) => void;
  ```

* Compilation configuration on Node-API:

  ```c++
  # entry/src/main/cpp/CMakeLists.txt
  # the minimum version of CMake.
  cmake_minimum_required(VERSION 3.4.1)
  project(NDKPostMessage)

  set(NATIVERENDER_ROOT_PATH ${CMAKE_CURRENT_SOURCE_DIR})

  if(DEFINED PACKAGE_FIND_FILE)
      include(${PACKAGE_FIND_FILE})
  endif()

  include_directories(${NATIVERENDER_ROOT_PATH}
                      ${NATIVERENDER_ROOT_PATH}/include)

  add_library(entry SHARED hello.cpp)

  find_library(
      # Sets the name of the path variable.
      hilog-lib
      # Specifies the name of the NDK library that
      # you want CMake to locate.
      hilog_ndk.z
  )

  target_link_libraries(entry PUBLIC libace_napi.z.so ${hilog-lib} libohweb.so)
  ```

* Node-API layer code:

  ```c++
  // entry/src/main/cpp/hello.cpp
  #include "napi/native_api.h"
  #include <bits/alltypes.h>
  #include <memory>
  #include <string>
  #include <sys/types.h>
  #include <iostream>
  #include <map>
  #include "hilog/log.h"
  #include "web/arkweb_interface.h"
  #include <thread>

  constexpr unsigned int LOG_PRINT_DOMAIN = 0xFF00;
  ArkWeb_ControllerAPI *controller = nullptr;

  ArkWeb_WebMessagePortAPI *webMessagePort = nullptr;
  ArkWeb_WebMessageAPI *webMessage = nullptr;
  size_t web_message_port_size = 0;
  ArkWeb_WebMessagePortPtr *g_web_message_port_arr = nullptr;

  static void WebMessagePortCallback(const char *webTag, const ArkWeb_WebMessagePortPtr port,
                                    const ArkWeb_WebMessagePtr message, void *userData) {
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb",
                  "ndk WebMesagePortCallback webTag:%{public}s,messageType:%{public}d", webTag,
                  webMessage->getType(message));
      size_t len = 0;
      void *back = webMessage->getData(message, &len);
      if (webMessage->getType(message) == ArkWeb_WebMessageType::ARKWEB_STRING) {
          OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb",
                      "ndk WebMesagePortCallback message:%{public}s,messageSize:%{public}d", back, len);
      } else if (webMessage->getType(message) == ArkWeb_WebMessageType::ARKWEB_BUFFER) {
          OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb",
                      "ndk WebMesagePortCallback messageSize:%{public}d", len);
      }
  }

  static napi_value NativeWebInit(napi_env env, napi_callback_info info) {
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb", "ndk NativeWebInit start");
      size_t argc = 1;
      napi_value args[1] = {nullptr};
      napi_get_cb_info(env, info, &argc, args, nullptr, nullptr);
      // Obtain the first parameter webTag.
      size_t webTagSize = 0;
      napi_get_value_string_utf8(env, args[0], nullptr, 0, &webTagSize);
      char *webTagValue = new (std::nothrow) char[webTagSize + 1];
      size_t webTagLength = 0;
      napi_get_value_string_utf8(env, args[0], webTagValue, webTagSize + 1, &webTagLength);
      OH_LOG_Print(LOG_APP, LOG_ERROR, LOG_PRINT_DOMAIN, "ArkWeb", "ndk NativeWebInit webTag:%{public}s", webTagValue);

      controller = reinterpret_cast<ArkWeb_ControllerAPI *>(OH_ArkWeb_GetNativeAPI(ARKWEB_NATIVE_CONTROLLER));
      if (controller)
          OH_LOG_Print(LOG_APP, LOG_ERROR, LOG_PRINT_DOMAIN, "ArkWeb", "get ArkWeb_ControllerAPI success");

      webMessagePort =
          reinterpret_cast<ArkWeb_WebMessagePortAPI *>(OH_ArkWeb_GetNativeAPI(ARKWEB_NATIVE_WEB_MESSAGE_PORT));
      if (webMessagePort)
          OH_LOG_Print(LOG_APP, LOG_ERROR, LOG_PRINT_DOMAIN, "ArkWeb", "get ArkWeb_WebMessagePortAPI success");

      webMessage = reinterpret_cast<ArkWeb_WebMessageAPI *>(OH_ArkWeb_GetNativeAPI(ARKWEB_NATIVE_WEB_MESSAGE));
      if (webMessage)
          OH_LOG_Print(LOG_APP, LOG_ERROR, LOG_PRINT_DOMAIN, "ArkWeb", "get ArkWeb_WebMessageAPI success");

      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb", "ndk NativeWebInit end");

      return nullptr;
  }

  static napi_value createWebMessagePorts(napi_env env, napi_callback_info info) {
      size_t argc = 2;
      napi_value args[2] = {nullptr};
      napi_get_cb_info(env, info, &argc, args, nullptr, nullptr);

      // Obtain the first parameter webTag.
      size_t webTagSize = 0;
      napi_get_value_string_utf8(env, args[0], nullptr, 0, &webTagSize);
      char *webTagValue = new (std::nothrow) char[webTagSize + 1];
      size_t webTagLength = 0;
      napi_get_value_string_utf8(env, args[0], webTagValue, webTagSize + 1, &webTagLength);
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb", "ndk Refresh webTag:%{public}s", webTagValue);

      // Initialize the ports.
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb", "ndk createWebMessagePorts begin");
      g_web_message_port_arr = controller->createWebMessagePorts(webTagValue, &web_message_port_size);
      // Send one of the ports to the HTML page.
      ArkWeb_ErrorCode code =
          controller->postWebMessage(webTagValue, "init_web_messageport", g_web_message_port_arr, 1, "*");
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb", "ndk postWebMessage ArkWeb_ErrorCode:%{public}d", code);
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb",
                  "ndk createWebMessagePorts end, web message port size:%{public}d", web_message_port_size);
      return nullptr;
  }

  static napi_value postMessage(napi_env env, napi_callback_info info) {
      size_t argc = 2;
      napi_value args[2] = {nullptr};
      napi_get_cb_info(env, info, &argc, args, nullptr, nullptr);

      // Obtain the first parameter webTag.
      size_t webTagSize = 0;
      napi_get_value_string_utf8(env, args[0], nullptr, 0, &webTagSize);
      char *webTagValue = new (std::nothrow) char[webTagSize + 1];
      size_t webTagLength = 0;
      napi_get_value_string_utf8(env, args[0], webTagValue, webTagSize + 1, &webTagLength);
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb", "ndk Refresh webTag:%{public}s", webTagValue);

      // Send a message.
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb", "ndk postMessage begin");

      if (g_web_message_port_arr == nullptr) {
          OH_LOG_Print(LOG_APP, LOG_ERROR, LOG_PRINT_DOMAIN, "ArkWeb", "webMessagePort is nullptr");
          return nullptr;
      }
      ArkWeb_WebMessagePtr message = webMessage->createWebMessage();
      webMessage->setType(message, ArkWeb_WebMessageType::ARKWEB_STRING);
      std::string str = "send string from native";
      webMessage->setData(message, (void *)str.c_str(), str.length() + 1);
      ArkWeb_ErrorCode code = webMessagePort->postMessage(g_web_message_port_arr[1], webTagValue, message);
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb", "ndk postMessage ArkWeb_ErrorCode:%{public}d", code);
      webMessage->destroyWebMessage(&message);
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb", "ndk postMessage end, web message port size:%{public}d",
                  web_message_port_size);
      return nullptr;
  }

  // Send a message in the thread.
  void sendMessage(const char *webTag, const ArkWeb_WebMessagePtr message) {
      // Send the message for 1000 times.
      for (int i = 0; i < 1000; i++) {
          OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb", "sendMessage in thread %{public}d", i);
          if (g_web_message_port_arr && webTag && message) {
            webMessagePort->postMessage(g_web_message_port_arr[1], webTag, message);
          }
      }
  }
  static napi_value postMessageThread(napi_env env, napi_callback_info info) {
      size_t argc = 2;
      napi_value args[2] = {nullptr};
      napi_get_cb_info(env, info, &argc, args, nullptr, nullptr);

      // Obtain the first parameter webTag.
      size_t webTagSize = 0;
      napi_get_value_string_utf8(env, args[0], nullptr, 0, &webTagSize);
      char *webTagValue = new (std::nothrow) char[webTagSize + 1];
      size_t webTagLength = 0;
      napi_get_value_string_utf8(env, args[0], webTagValue, webTagSize + 1, &webTagLength);
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb", "ndk Refresh webTag:%{public}s", webTagValue);

      // Construct a message.
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb", "ndk postMessage begin");

      if (g_web_message_port_arr == nullptr) {
          OH_LOG_Print(LOG_APP, LOG_ERROR, LOG_PRINT_DOMAIN, "ArkWeb", "webMessagePort is nullptr");
          return nullptr;
      }
      ArkWeb_WebMessagePtr message = webMessage->createWebMessage();
      webMessage->setType(message, ArkWeb_WebMessageType::ARKWEB_STRING);
      std::string str = "thread message";
      webMessage->setData(message, (void *)str.c_str(), str.length() + 1);
      const int numThreads = 5;
      std::thread threads[numThreads];

      // Create the threads.
      for (int i = 0; i < numThreads; ++i) {
          threads[i] = std::thread(sendMessage, webTagValue, message);
      }

      // Wait until all threads are detached.
      for (int i = 0; i < numThreads; ++i) {
          threads[i].detach();
      }
      return nullptr;
  }

  // Register a callback in the thread.
  void setHandler(const char *webTag) {
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb", "setMessageEventHandler in thread");
      webMessagePort->setMessageEventHandler(g_web_message_port_arr[1], webTag, WebMessagePortCallback, NULL);
  }

  static napi_value setMessageEventHandlerThread(napi_env env, napi_callback_info info) {
      size_t argc = 2;
      napi_value args[2] = {nullptr};
      napi_get_cb_info(env, info, &argc, args, nullptr, nullptr);

      // Obtain the first parameter webTag.
      size_t webTagSize = 0;
      napi_get_value_string_utf8(env, args[0], nullptr, 0, &webTagSize);
      char *webTagValue = new (std::nothrow) char[webTagSize + 1];
      size_t webTagLength = 0;
      napi_get_value_string_utf8(env, args[0], webTagValue, webTagSize + 1, &webTagLength);
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb", "ndk Refresh webTag:%{public}s", webTagValue);

      // Register a callback.
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb", "ndk SetMessageEventHandler begin");
      if (g_web_message_port_arr == nullptr) {
          OH_LOG_Print(LOG_APP, LOG_ERROR, LOG_PRINT_DOMAIN, "ArkWeb", "webMessagePort is nullptr");
          return nullptr;
      }
      std::thread thread(setHandler, webTagValue);
      thread.detach();
      webMessagePort->setMessageEventHandler(g_web_message_port_arr[1], webTagValue, WebMessagePortCallback, NULL);
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb",
                  "ndk SetMessageEventHandler end, web message port size:%{public}d", web_message_port_size);
      return nullptr;
  }
  static napi_value postNoneMessage(napi_env env, napi_callback_info info) {
      size_t argc = 2;
      napi_value args[2] = {nullptr};
      napi_get_cb_info(env, info, &argc, args, nullptr, nullptr);

      // Obtain the first parameter webTag.
      size_t webTagSize = 0;
      napi_get_value_string_utf8(env, args[0], nullptr, 0, &webTagSize);
      char *webTagValue = new (std::nothrow) char[webTagSize + 1];
      size_t webTagLength = 0;
      napi_get_value_string_utf8(env, args[0], webTagValue, webTagSize + 1, &webTagLength);
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb", "ndk Refresh webTag:%{public}s", webTagValue);

      // Send a message.
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb", "ndk postMessage begin");

      if (g_web_message_port_arr == nullptr) {
          OH_LOG_Print(LOG_APP, LOG_ERROR, LOG_PRINT_DOMAIN, "ArkWeb", "webMessagePort is nullptr");
          return nullptr;
      }
      ArkWeb_WebMessagePtr message = webMessage->createWebMessage();
      webMessage->setType(message, ArkWeb_WebMessageType::ARKWEB_NONE);
      std::string str = "send string from native";
      webMessage->setData(message, (void *)str.c_str(), str.length() + 1);
      webMessagePort->postMessage(g_web_message_port_arr[1], webTagValue, message);
      webMessage->destroyWebMessage(&message);
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb", "ndk postMessage end, web message port size:%{public}d",
                  web_message_port_size);
      return nullptr;
  }

  static napi_value postBufferMessage(napi_env env, napi_callback_info info) {
      size_t argc = 2;
      napi_value args[2] = {nullptr};
      napi_get_cb_info(env, info, &argc, args, nullptr, nullptr);

      // Obtain the first parameter webTag.
      size_t webTagSize = 0;
      napi_get_value_string_utf8(env, args[0], nullptr, 0, &webTagSize);
      char *webTagValue = new (std::nothrow) char[webTagSize + 1];
      size_t webTagLength = 0;
      napi_get_value_string_utf8(env, args[0], webTagValue, webTagSize + 1, &webTagLength);
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb", "ndk Refresh webTag:%{public}s", webTagValue);

      // Send a message.
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb", "ndk postMessage begin");

      if (g_web_message_port_arr == nullptr) {
          OH_LOG_Print(LOG_APP, LOG_ERROR, LOG_PRINT_DOMAIN, "ArkWeb", "webMessagePort is nullptr");
          return nullptr;
      }
      ArkWeb_WebMessagePtr message1 = webMessage->createWebMessage();
      webMessage->setType(message1, ArkWeb_WebMessageType::ARKWEB_BUFFER);
      std::string str1 = "send buffer from native";
      webMessage->setData(message1, (void *)str1.c_str(), str1.length());
      webMessagePort->postMessage(g_web_message_port_arr[1], webTagValue, message1);
      webMessage->destroyWebMessage(&message1);
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb", "ndk postMessage end, web message port size:%{public}d",
                  web_message_port_size);
      return nullptr;
  }

  static napi_value setMessageEventHandler(napi_env env, napi_callback_info info) {
      size_t argc = 2;
      napi_value args[2] = {nullptr};
      napi_get_cb_info(env, info, &argc, args, nullptr, nullptr);

      // Obtain the first parameter webTag.
      size_t webTagSize = 0;
      napi_get_value_string_utf8(env, args[0], nullptr, 0, &webTagSize);
      char *webTagValue = new (std::nothrow) char[webTagSize + 1];
      size_t webTagLength = 0;
      napi_get_value_string_utf8(env, args[0], webTagValue, webTagSize + 1, &webTagLength);
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb", "ndk Refresh webTag:%{public}s", webTagValue);

      // Register a callback.
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb", "ndk SetMessageEventHandler begin");
      if (g_web_message_port_arr == nullptr) {
          OH_LOG_Print(LOG_APP, LOG_ERROR, LOG_PRINT_DOMAIN, "ArkWeb", "webMessagePort is nullptr");
          return nullptr;
      }
      webMessagePort->setMessageEventHandler(g_web_message_port_arr[1], webTagValue, WebMessagePortCallback, NULL);
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb",
                  "ndk SetMessageEventHandler end, web message port size:%{public}d", web_message_port_size);
      return nullptr;
  }

  static napi_value closeMessagePort(napi_env env, napi_callback_info info) {
      size_t argc = 2;
      napi_value args[2] = {nullptr};
      napi_get_cb_info(env, info, &argc, args, nullptr, nullptr);

      // Obtain the first parameter webTag.
      size_t webTagSize = 0;
      napi_get_value_string_utf8(env, args[0], nullptr, 0, &webTagSize);
      char *webTagValue = new (std::nothrow) char[webTagSize + 1];
      size_t webTagLength = 0;
      napi_get_value_string_utf8(env, args[0], webTagValue, webTagSize + 1, &webTagLength);
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb", "ndk Refresh webTag:%{public}s", webTagValue);

      // Disable the port by calling close() and then destroyWebMessagePorts().
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb", "ndk SetMessageEventHandler begin");
      if (g_web_message_port_arr == nullptr) {
          OH_LOG_Print(LOG_APP, LOG_ERROR, LOG_PRINT_DOMAIN, "ArkWeb", "webMessagePort is nullptr");
          return nullptr;
      }
      webMessagePort->close(g_web_message_port_arr[0], webTagValue);
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb",
                  "ndk SetMessageEventHandler end, web message port size:%{public}d", web_message_port_size);
      controller->refresh(webTagValue);
      return nullptr;
  }

  static napi_value destroyMessagePort(napi_env env, napi_callback_info info) {
      size_t argc = 2;
      napi_value args[2] = {nullptr};
      napi_get_cb_info(env, info, &argc, args, nullptr, nullptr);

      // Obtain the first parameter webTag.
      size_t webTagSize = 0;
      napi_get_value_string_utf8(env, args[0], nullptr, 0, &webTagSize);
      char *webTagValue = new (std::nothrow) char[webTagSize + 1];
      size_t webTagLength = 0;
      napi_get_value_string_utf8(env, args[0], webTagValue, webTagSize + 1, &webTagLength);
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb", "ndk Refresh webTag:%{public}s", webTagValue);

      // Release the memory by calling close() and then destroyWebMessagePorts().
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb", "ndk SetMessageEventHandler begin");
      if (g_web_message_port_arr == nullptr) {
          OH_LOG_Print(LOG_APP, LOG_ERROR, LOG_PRINT_DOMAIN, "ArkWeb", "webMessagePort is nullptr");
          return nullptr;
      }
      controller->destroyWebMessagePorts(&g_web_message_port_arr, web_message_port_size);
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb",
                  "ndk SetMessageEventHandler end, web message port size:%{public}d", web_message_port_size);
      return nullptr;
  }

  static napi_value destroyNullMessagePort(napi_env env, napi_callback_info info) {
      size_t argc = 2;
      napi_value args[2] = {nullptr};
      napi_get_cb_info(env, info, &argc, args, nullptr, nullptr);

      // Obtain the first parameter webTag.
      size_t webTagSize = 0;
      napi_get_value_string_utf8(env, args[0], nullptr, 0, &webTagSize);
      char *webTagValue = new (std::nothrow) char[webTagSize + 1];
      size_t webTagLength = 0;
      napi_get_value_string_utf8(env, args[0], webTagValue, webTagSize + 1, &webTagLength);
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb", "ndk Refresh webTag:%{public}s", webTagValue);

      // Release the memory by calling close() and then destroyWebMessagePorts().
      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb", "ndk SetMessageEventHandler begin");

      controller->destroyWebMessagePorts(&g_web_message_port_arr, web_message_port_size);

      OH_LOG_Print(LOG_APP, LOG_INFO, LOG_PRINT_DOMAIN, "ArkWeb",
                  "ndk SetMessageEventHandler end, web message port size:%{public}d", web_message_port_size);
      return nullptr;
  }

  EXTERN_C_START
  static napi_value Init(napi_env env, napi_value exports) {
      napi_property_descriptor desc[] = {
          {"nativeWebInit", nullptr, NativeWebInit, nullptr, nullptr, nullptr, napi_default, nullptr},
          {"createWebMessagePorts", nullptr, createWebMessagePorts, nullptr, nullptr, nullptr, napi_default, nullptr},
          {"postMessage", nullptr, postMessage, nullptr, nullptr, nullptr, napi_default, nullptr},
          {"postNoneMessage", nullptr, postNoneMessage, nullptr, nullptr, nullptr, napi_default, nullptr},
          {"postBufferMessage", nullptr, postBufferMessage, nullptr, nullptr, nullptr, napi_default, nullptr},
          {"setMessageEventHandler", nullptr, setMessageEventHandler, nullptr, nullptr, nullptr, napi_default, nullptr},
          {"closeMessagePort", nullptr, closeMessagePort, nullptr, nullptr, nullptr, napi_default, nullptr},
          {"destroyMessagePort", nullptr, destroyMessagePort, nullptr, nullptr, nullptr, napi_default, nullptr},
          {"postMessageThread", nullptr, postMessageThread, nullptr, nullptr, nullptr, napi_default, nullptr},
          {"setMessageEventHandlerThread", nullptr, setMessageEventHandlerThread, nullptr, nullptr, nullptr, napi_default,
          nullptr},
          {"destroyNullMessagePort", nullptr, destroyNullMessagePort, nullptr, nullptr, nullptr, napi_default, nullptr},
      };
      napi_define_properties(env, exports, sizeof(desc) / sizeof(desc[0]), desc);
      return exports;
  }
  EXTERN_C_END

  static napi_module demoModule = {
      .nm_version = 1,
      .nm_flags = 0,
      .nm_filename = nullptr,
      .nm_register_func = Init,
      .nm_modname = "entry",
      .nm_priv = ((void *)0),
      .reserved = {0},
  };

  extern "C" __attribute__((constructor)) void RegisterEntryModule(void) { napi_module_register(&demoModule); }
  ```