# Socket Connection

> **NOTE**<br>
> The initial APIs of this module are supported since API version 7. Newly added APIs will be marked with a superscript to indicate their earliest API version.

## Modules to Import

```
import socket from '@ohos.net.socket';
```

## socket.constructUDPSocketInstance

constructUDPSocketInstance\(\): UDPSocket

Creates a **UDPSocket** object.

**System capability**: SystemCapability.Communication.NetStack

**Return Value**

| Type                              | Description                   |
| :--------------------------------- | :---------------------- |
| [UDPSocket](#udpsocket) | **UDPSocket** object.|


**Example**

```
let udp = socket.constructUDPSocketInstance();
```


## UDPSocket

Defines a **UDPSocket** connection. Before invoking UDPSocket APIs, you need to call [socket.constructUDPSocketInstance](#socketconstructudpsocketinstance) to create a **UDPSocket** object.

### bind

bind\(address: NetAddress, callback: AsyncCallback<void\>\): void

Binds the IP address and port number. The port number can be specified or randomly allocated by the system. This API uses an asynchronous callback to return the result.

**Required permission**: ohos.permission.INTERNET

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name  | Type                              | Mandatory| Description                                                  |
| -------- | ---------------------------------- | ---- | ------------------------------------------------------ |
| address  | [NetAddress](#netaddress) | Yes  | Destination address. For details, see [NetAddress](#netaddress).|
| callback | AsyncCallback\<void\>              | Yes  | Callback used to return the result.                                            |

**Example**

```
let udp = socket.constructUDPSocketInstance();
udp.bind({address: '192.168.xx.xxx', port: xxxx, family: 1}, err => {
  if (err) {
	console.log('bind fail');
	return;
  }
  console.log('bind success');
})
```


### bind

bind\(address: NetAddress\): Promise<void\>

Binds the IP address and port number. The port number can be specified or randomly allocated by the system. This API uses a promise to return the result.

**Required permission**: ohos.permission.INTERNET

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name | Type                              | Mandatory| Description                                                  |
| ------- | ---------------------------------- | ---- | ------------------------------------------------------ |
| address | [NetAddress](#netaddress) | Yes  | Destination address. For details, see [NetAddress](#netaddress).|


**Return Value**

| Type           | Description                                      |
| :-------------- | :----------------------------------------- |
| Promise\<void\> | Promise used to return the result.|

**Example**

```
let udp = socket.constructUDPSocketInstance();
let promise = udp.bind({address: '192.168.xx.xxx', port: 8080, family: 1});
promise .then(() => {
  console.log('bind success');
}).catch(err => {
  console.log('bind fail');
});
```


### send

send\(options: UDPSendOptions, callback: AsyncCallback<void\>\): void

Sends data over a UDPSocket connection. This API uses an asynchronous callback to return the result.

Before sending data, call [UDPSocket.bind()](#bind) to bind the IP address and port.

**Required permission**: ohos.permission.INTERNET

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name  | Type                                    | Mandatory| Description                                                        |
| -------- | ---------------------------------------- | ---- | ------------------------------------------------------------ |
| options  | [UDPSendOptions](#udpsendoptions) | Yes  | Parameters for sending data over the UDPSocket connection. For details, see [UDPSendOptions](#udpsendoptions).|
| callback | AsyncCallback\<void\>                    | Yes  | Callback used to return the result.                                                  |

**Example**

```
let udp = socket.constructUDPSocketInstance();
udp.send({
  data:'Hello, server!',
  address: {
	address:'192.168.xx.xxx',
	port:xxxx,
	family:1
  }
}, err=> {
	if (err) {
	  console.log('send fail');
	  return;
	}
	console.log('send success');
})
```


### send

send\(options: UDPSendOptions\): Promise<void\>

Sends data over a UDPSocket connection. This API uses a promise to return the result.

Before sending data, call [UDPSocket.bind()](#bind) to bind the IP address and port.

**Required permission**: ohos.permission.INTERNET

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name | Type                                    | Mandatory| Description                                                        |
| ------- | ---------------------------------------- | ---- | ------------------------------------------------------------ |
| options | [UDPSendOptions](#udpsendoptions) | Yes  | Parameters for sending data over the UDPSocket connection. For details, see [UDPSendOptions](#udpsendoptions).|

**Return Value**

| Type           | Description                                          |
| :-------------- | :--------------------------------------------- |
| Promise\<void\> | Promise used to return the result.|

**Example**

```
let udp = socket.constructUDPSocketInstance();
let promise = udp.send({
  data:'Hello, server!',
  address: {
	address:'192.168.xx.xxx',
	port:xxxx,
	family:1
  }
});
promise.then(() => {
  console.log('send success');
}).catch(err => {
  console.log('send fail');
});
```


### close

close\(callback: AsyncCallback<void\>\): void

Closes a UDPSocket connection. This API uses an asynchronous callback to return the result.

**Required permission**: ohos.permission.INTERNET

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name  | Type                 | Mandatory| Description      |
| -------- | --------------------- | ---- | ---------- |
| callback | AsyncCallback\<void\> | Yes  | Callback used to return the result.|

**Example**

```
let udp = socket.constructUDPSocketInstance();
udp.close(err => {
  if (err) {
	console.log('close fail');
	return;
  }
  console.log('close success');
})
```


### close

close\(\): Promise<void\>

Closes a UDPSocket connection. This API uses a promise to return the result.

**Required permission**: ohos.permission.INTERNET

**System capability**: SystemCapability.Communication.NetStack

**Return Value**

| Type           | Description                                      |
| :-------------- | :----------------------------------------- |
| Promise\<void\> | Promise used to return the result.|

**Example**

```
let udp = socket.constructUDPSocketInstance();
let promise = udp.close();
promise.then(() => {
  console.log('close success');
}).catch(err => {
  console.log('close fail');
});
```


### getState

getState\(callback: AsyncCallback<SocketStateBase\>\): void

Obtains the status of the UDPSocket connection. This API uses an asynchronous callback to return the result.

>![](public_sys-resources/icon-note.gif) **NOTE:**
>This API can be called only after [bind](#bind) is successfully called.

**Required permission**: ohos.permission.INTERNET

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name  | Type                                                  | Mandatory| Description      |
| -------- | ------------------------------------------------------ | ---- | ---------- |
| callback | AsyncCallback<[SocketStateBase](#socketstatebase)> | Yes  | Callback used to return the result.|

**Example**

```
let udp = socket.constructUDPSocketInstance();
udp.bind({address: '192.168.xx.xxx', port: xxxx, family: 1}, err => {
  if (err) {
	console.log('bind fail');
	return;
  }
  console.log('bind success');
  udp.getState((err, data) => {
	if (err) {
	  console.log('getState fail');
	  return;
	}
	console.log('getState success:' + JSON.stringify(data));
  })
})
```


### getState

getState\(\): Promise<SocketStateBase\>

Obtains the status of the UDPSocket connection. This API uses a promise to return the result.

>![](public_sys-resources/icon-note.gif) **NOTE:**
>This API can be called only after [bind](#bind) is successfully called.

**Required permission**: ohos.permission.INTERNET

**System capability**: SystemCapability.Communication.NetStack

**Return Value**

| Type                                            | Description                                      |
| :----------------------------------------------- | :----------------------------------------- |
| Promise<[SocketStateBase](#socketstatebase)> | Promise used to return the result.|

**Example**

```
let udp = socket.constructUDPSocketInstance();
udp.bind({address: '192.168.xx.xxx', port: xxxx, family: 1}, err => {
  if (err) {
	console.log('bind fail');
	return;
  }
  console.log('bind success');
  let promise = udp.getState({});
  promise.then(data => {
	console.log('getState success:' + JSON.stringify(data));
  }).catch(err => {
	console.log('getState fail');
  });
})
```


### setExtraOptions

setExtraOptions\(options: UDPExtraOptions, callback: AsyncCallback<void\>\): void

Sets other properties of the UDPSocket connection. This API uses an asynchronous callback to return the result.

>![](public_sys-resources/icon-note.gif) **NOTE:**
>This API can be called only after [bind](#bind) is successfully called.

**Required permission**: ohos.permission.INTERNET

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name  | Type                                    | Mandatory| Description                                                        |
| -------- | ---------------------------------------- | ---- | ------------------------------------------------------------ |
| options  | [UDPExtraOptions](#udpextraoptions) | Yes  | Other properties of the UDPSocket connection. For details, see [UDPExtraOptions](#udpextraoptions).|
| callback | AsyncCallback\<void\>                    | Yes  | Callback used to return the result.                                                  |


**Example**

```
let udp = socket.constructUDPSocketInstance();
udp.bind({address:'192.168.xx.xxx', port:xxxx, family:1}, err=> {
  if (err) {
	console.log('bind fail');
	return;
  }
  console.log('bind success');
  udp.setExtraOptions({
	receiveBufferSize:1000,
	sendBufferSize:1000,
	reuseAddress:false,
	socketTimeout:6000,
	broadcast:true
  }, err=> {
	if (err) {
	  console.log('setExtraOptions fail');
	  return;
	}
	console.log('setExtraOptions success');
  })
})
```


### setExtraOptions

setExtraOptions\(options: UDPExtraOptions\): Promise<void\>

Sets other properties of the UDPSocket connection. This API uses a promise to return the result.

>![](public_sys-resources/icon-note.gif) **NOTE:**
>This API can be called only after [bind](#bind) is successfully called.

**Required permission**: ohos.permission.INTERNET

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name | Type                                    | Mandatory| Description                                                        |
| ------- | ---------------------------------------- | ---- | ------------------------------------------------------------ |
| options | [UDPExtraOptions](#udpextraoptions) | Yes  | Other properties of the UDPSocket connection. For details, see [UDPExtraOptions](#udpextraoptions).|

**Return Value**

| Type           | Description                                                |
| :-------------- | :--------------------------------------------------- |
| Promise\<void\> | Promise used to return the result.|

**Example**

```
let udp = socket.constructUDPSocketInstance();
let promise = udp.bind({address:'192.168.xx.xxx', port:xxxx, family:1});
promise.then(() => {
  console.log('bind success');
  let promise1 = udp.setExtraOptions({
	receiveBufferSize:1000,
	sendBufferSize:1000,
	reuseAddress:false,
	socketTimeout:6000,
	broadcast:true
  });
  promise1.then(() => {
	console.log('setExtraOptions success');
  }).catch(err => {
	console.log('setExtraOptions fail');
  });
}).catch(err => {
  console.log('bind fail');
});
```


### on\('message'\)

on\(type: 'message', callback: Callback<\{message: ArrayBuffer, remoteInfo: SocketRemoteInfo\}\>\): void

Enables listening for message receiving events of the UDPSocket connection. This API uses an asynchronous callback to return the result.

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name  | Type                                                        | Mandatory| Description                                     |
| -------- | ------------------------------------------------------------ | ---- | ----------------------------------------- |
| type     | string                                                       | Yes  | Event type. <br />**message**: message receiving event|
| callback | Callback<{message: ArrayBuffer, remoteInfo: [SocketRemoteInfo](#socketremoteinfo)}> | Yes  | Callback used to return the result.                               |

**Example**

```
let udp = socket.constructUDPSocketInstance();
udp.on('message', value => {
	console.log("on message, message:" + value.message + ", remoteInfo:" + value.remoteInfo);
});
```


### off\('message'\)

off\(type: 'message', callback?: Callback<\{message: ArrayBuffer, remoteInfo: SocketRemoteInfo\}\>\): void

Disables listening for message receiving events of the UDPSocket connection. This API uses an asynchronous callback to return the result.

>![](public_sys-resources/icon-note.gif) **NOTE:**
>You can pass the callback of the **on** function if you want to cancel listening for a certain type of event. If you do not pass the callback, you will cancel listening for all events.

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name  | Type                                                        | Mandatory| Description                                     |
| -------- | ------------------------------------------------------------ | ---- | ----------------------------------------- |
| type     | string                                                       | Yes  | Event type. <br />**message**: message receiving event|
| callback | Callback<{message: ArrayBuffer, remoteInfo: [SocketRemoteInfo](#socketremoteinfo)}> | No  | Callback used to return the result.                               |

**Example**

```
let udp = socket.constructUDPSocketInstance();
let callback = value =>{
	console.log("on message, message:" + value.message + ", remoteInfo:" + value.remoteInfo);
}
udp.on('message', callback);
// You can pass the callback of the on function to cancel listening for a certain type of callback. If you do not pass the callback, you will cancel listening for all callbacks.
udp.off('message', callback);
udp.off('message');
```


### on\('listening' | 'close'\)

on\(type: 'listening' | 'close', callback: Callback<void\>\): void

Enables listening for data packet message events or close events of the UDPSocket connection. This API uses an asynchronous callback to return the result.

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name  | Type            | Mandatory| Description                                                        |
| -------- | ---------------- | ---- | ------------------------------------------------------------ |
| type     | string           | Yes  | Event type.<br>- **listening**: data packet message event<br>- **close**: close event|
| callback | Callback\<void\> | Yes  | Callback used to return the result.                                                  |

**Example**

```
let udp = socket.constructUDPSocketInstance();
udp.on('listening', () => {
	console.log("on listening success");
});
udp.on('close', () => {
	console.log("on close success" );
});
```


### off\('listening' | 'close'\)

off\(type: 'listening' | 'close', callback?: Callback<void\>\): void

Disables listening for data packet message events or close events of the UDPSocket connection. This API uses an asynchronous callback to return the result.

>![](public_sys-resources/icon-note.gif) **NOTE:**
>You can pass the callback of the **on** function if you want to cancel listening for a certain type of event. If you do not pass the callback, you will cancel listening for all events.

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name  | Type            | Mandatory| Description                                                        |
| -------- | ---------------- | ---- | ------------------------------------------------------------ |
| type     | string           | Yes  | Event type.<br>- **listening**: data packet message event<br>- **close**: close event|
| callback | Callback\<void\> | No  | Callback used to return the result.                                                  |

**Example**

```
let udp = socket.constructUDPSocketInstance();
let callback1 = () =>{
	console.log("on listening, success");
}
udp.on('listening', callback1);
// You can pass the callback of the on function to cancel listening for a certain type of callback. If you do not pass the callback, you will cancel listening for all callbacks.
udp.off('listening', callback1);
udp.off('listening');
let callback2 = () =>{
	console.log("on close, success");
}
udp.on('close', callback2);
// You can pass the callback of the on function to cancel listening for a certain type of callback. If you do not pass the callback, you will cancel listening for all callbacks.
udp.off('close', callback2);
udp.off('close');
```


### on\('error'\)

on\(type: 'error', callback: ErrorCallback\): void

Enables listening for error events of the UDPSocket connection. This API uses an asynchronous callback to return the result.

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name  | Type         | Mandatory| Description                                |
| -------- | ------------- | ---- | ------------------------------------ |
| type     | string        | Yes  | Event type. <br />**error**: error event|
| callback | ErrorCallback | Yes  | Callback used to return the result.                          |


**Example**

```
let udp = socket.constructUDPSocketInstance();
udp.on('error', err => {
	console.log("on error, err:" + JSON.stringify(err))
});
```


### off\('error'\)

off\(type: 'error', callback?: ErrorCallback\): void

Disables listening for error events of the UDPSocket connection. This API uses an asynchronous callback to return the result.

>![](public_sys-resources/icon-note.gif) **NOTE:**
>You can pass the callback of the **on** function if you want to cancel listening for a certain type of event. If you do not pass the callback, you will cancel listening for all events.

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name  | Type         | Mandatory| Description                                |
| -------- | ------------- | ---- | ------------------------------------ |
| type     | string        | Yes  | Event type. <br />**error**: error event|
| callback | ErrorCallback | No  | Callback used to return the result.                          |

**Example**

```
let udp = socket.constructUDPSocketInstance();
let callback = err =>{
	console.log("on error, err:" + JSON.stringify(err));
}
udp.on('error', callback);
// You can pass the callback of the on function to cancel listening for a certain type of callback. If you do not pass the callback, you will cancel listening for all callbacks.
udp.off('error', callback);
udp.off('error');
```


## NetAddress

Defines the destination address.

**System capability**: SystemCapability.Communication.NetStack

| Name | Type  | Mandatory| Description                                                        |
| ------- | ------ | ---- | ------------------------------------------------------------ |
| address | string | Yes  | Bound IP address.                                          |
| port    | number | No  | Port number. The value ranges from **0** to **65535**. If this parameter is not specified, the system randomly allocates a port.          |
| family  | number | No  | Network protocol type.<br>- **1**: IPv4<br>- **2**: IPv6<br>The default value is **1**.|

## UDPSendOptions

Defines the parameters for sending data over the UDPSocket connection.

**System capability**: SystemCapability.Communication.NetStack

| Name | Type                              | Mandatory| Description          |
| ------- | ---------------------------------- | ---- | -------------- |
| data    | string                             | Yes  | Data to send.  |
| address | [NetAddress](#netaddress) | Yes  | Destination address.|

## UDPExtraOptions

Defines other properties of the UDPSocket connection.

**System capability**: SystemCapability.Communication.NetStack

| Name           | Type   | Mandatory| Description                            |
| ----------------- | ------- | ---- | -------------------------------- |
| broadcast         | boolean | No  | Whether to send broadcast messages. The default value is **false**. |
| receiveBufferSize | number  | No  | Size of the receive buffer, in bytes.  |
| sendBufferSize    | number  | No  | Size of the send buffer, in bytes.  |
| reuseAddress      | boolean | No  | Whether to reuse addresses. The default value is **false**.     |
| socketTimeout     | number  | No  | Timeout duration of the UDPSocket connection, in ms.|

## SocketStateBase

Defines the status of the UDPSocket connection.

**System capability**: SystemCapability.Communication.NetStack

| Name     | Type   | Mandatory| Description      |
| ----------- | ------- | ---- | ---------- |
| isBound     | boolean | Yes  | Whether the connection is in the bound state.|
| isClose     | boolean | Yes  | Whether the connection is in the closed state.|
| isConnected | boolean | Yes  | Whether the connection is in the connected state.|

## SocketRemoteInfo

Defines information about the UDPSocket connection.

**System capability**: SystemCapability.Communication.NetStack

| Name | Type  | Mandatory| Description                                                        |
| ------- | ------ | ---- | ------------------------------------------------------------ |
| address | string | Yes  | Bound IP address.                                          |
| family  | string | Yes  | Network protocol type.<br>- IPv4<br>- IPv6<br>The default value is **IPv4**.|
| port    | number | Yes  | Port number. The value ranges from **0** to **65535**.                                       |
| size    | number | Yes  | Length of the server response message, in bytes.                                  |

## socket.constructTCPSocketInstance

constructTCPSocketInstance\(\): TCPSocket

Creates a **TCPSocket** object.

**System capability**: SystemCapability.Communication.NetStack

**Return Value**

  | Type                              | Description                   |
  | :--------------------------------- | :---------------------- |
  | [TCPSocket](#tcpsocket) | **TCPSocket** object.|

**Example**

```
let tcp = socket.constructTCPSocketInstance();
```


## TCPSocket

Defines a TCPSocket connection. Before invoking TCPSocket APIs, you need to call [socket.constructTCPSocketInstance](#socketconstructtcpsocketinstance) to create a **TCPSocket** object.

### bind

bind\(address: NetAddress, callback: AsyncCallback<void\>\): void

Binds the IP address and port number. The port number can be specified or randomly allocated by the system. This API uses an asynchronous callback to return the result.

**Required permission**: ohos.permission.INTERNET

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name  | Type                              | Mandatory| Description                                                  |
| -------- | ---------------------------------- | ---- | ------------------------------------------------------ |
| address  | [NetAddress](#netaddress) | Yes  | Destination address. For details, see [NetAddress](#netaddress).|
| callback | AsyncCallback\<void\>              | Yes  | Callback used to return the result.                                            |


**Example**

```
let tcp = socket.constructTCPSocketInstance();
tcp.bind({address: '192.168.xx.xxx', port: xxxx, family: 1}, err => {
  if (err) {
	console.log('bind fail');
	return;
  }
  console.log('bind success');
})
```


### bind

bind\(address: NetAddress\): Promise<void\>

Binds the IP address and port number. The port number can be specified or randomly allocated by the system. This API uses a promise to return the result.

**Required permission**: ohos.permission.INTERNET

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name | Type                              | Mandatory| Description                                                  |
| ------- | ---------------------------------- | ---- | ------------------------------------------------------ |
| address | [NetAddress](#netaddress) | Yes  | Destination address. For details, see [NetAddress](#netaddress).|

**Return Value**

| Type           | Description                                                    |
| :-------------- | :------------------------------------------------------- |
| Promise\<void\> | Promise used to return the result.|

**Example**

```
let tcp = socket.constructTCPSocketInstance();
let promise = tcp.bind({address: '192.168.xx.xxx', port: xxxx, family: 1});
promise.then(() => {
  console.log('bind success');
}).catch(err => {
  console.log('bind fail');
});
```


### connect

connect\(options: TCPConnectOptions, callback: AsyncCallback<void\>\): void

Sets up a connection to the specified IP address and port number. This API uses an asynchronous callback to return the result.

**Required permission**: ohos.permission.INTERNET

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name  | Type                                    | Mandatory| Description                                                        |
| -------- | ---------------------------------------- | ---- | ------------------------------------------------------------ |
| options  | [TCPConnectOptions](#tcpconnectoptions) | Yes  | TCPSocket connection parameters. For details, see [TCPConnectOptions](#tcpconnectoptions).|
| callback | AsyncCallback\<void\>                    | Yes  | Callback used to return the result.                                                  |

**Example**

```
let tcp = socket.constructTCPSocketInstance();
tcp.connect({ address: {address: '192.168.xx.xxx', port: xxxx, family: 1} , timeout: 6000}, err => {
  if (err) {
	console.log('connect fail');
	return;
  }
  console.log('connect success');
})
```


### connect

connect\(options: TCPConnectOptions\): Promise<void\>

Sets up a connection to the specified IP address and port number. This API uses a promise to return the result.

**Required permission**: ohos.permission.INTERNET

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name | Type                                    | Mandatory| Description                                                        |
| ------- | ---------------------------------------- | ---- | ------------------------------------------------------------ |
| options | [TCPConnectOptions](#tcpconnectoptions) | Yes  | TCPSocket connection parameters. For details, see [TCPConnectOptions](#tcpconnectoptions).|

**Return Value**

| Type           | Description                                                      |
| :-------------- | :--------------------------------------------------------- |
| Promise\<void\> | Promise used to return the result.|

**Example**

```
let tcp = socket.constructTCPSocketInstance();
let promise = tcp.connect({ address: {address: '192.168.xx.xxx', port: xxxx, family: 1} , timeout: 6000});
promise.then(() => {
  console.log('connect success')
}).catch(err => {
  console.log('connect fail');
});
```


### send

send\(options: TCPSendOptions, callback: AsyncCallback<void\>\): void

Sends data over a TCPSocket connection. This API uses an asynchronous callback to return the result.

>![](public_sys-resources/icon-note.gif) **NOTE:**
>This API can be called only after [connect](#connect) is successfully called.

**Required permission**: ohos.permission.INTERNET

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name  | Type                                   | Mandatory| Description                                                        |
| -------- | --------------------------------------- | ---- | ------------------------------------------------------------ |
| options  | [TCPSendOptions](#tcpsendoptions) | Yes  | Parameters for sending data over the TCPSocket connection. For details, see [TCPSendOptions](#tcpsendoptions).|
| callback | AsyncCallback\<void\>                   | Yes  | Callback used to return the result.                                                  |

**Example**

```
let tcp = socket.constructTCPSocketInstance();
let promise = tcp.connect({ address: {address: '192.168.xx.xxx', port: xxxx, family: 1} , timeout: 6000});
promise.then(() => {
  console.log('connect success');
  tcp.send({
	data:'Hello, server!'
  },err => {
	if (err) {
	  console.log('send fail');
	  return;
	}
	console.log('send success');
  })
}).catch(err => {
  console.log('connect fail');
});
```


### send

send\(options: TCPSendOptions\): Promise<void\>

Sends data over a TCPSocket connection. This API uses a promise to return the result.

>![](public_sys-resources/icon-note.gif) **NOTE:**
>This API can be called only after [connect](#connect) is successfully called.

**Required permission**: ohos.permission.INTERNET

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name | Type                                   | Mandatory| Description                                                        |
| ------- | --------------------------------------- | ---- | ------------------------------------------------------------ |
| options | [TCPSendOptions](#tcpsendoptions) | Yes  | Parameters for sending data over the TCPSocket connection. For details, see [TCPSendOptions](#tcpsendoptions).|

**Return Value**

| Type           | Description                                              |
| :-------------- | :------------------------------------------------- |
| Promise\<void\> | Promise used to return the result.|

**Example**

```
let tcp = socket.constructTCPSocketInstance();
let promise1 = tcp.connect({ address: {address: '192.168.xx.xxx', port: xxxx, family: 1} , timeout: 6000});
promise1.then(() => {
  console.log('connect success');
  let promise2 = tcp.send({
	data:'Hello, server!'
  });
  promise2.then(() => {
	console.log('send success');
  }).catch(err => {
	console.log('send fail');
  });
}).catch(err => {
  console.log('connect fail');
});
```


### close

close\(callback: AsyncCallback<void\>\): void

Closes a TCPSocket connection. This API uses an asynchronous callback to return the result.

**Required permission**: ohos.permission.INTERNET

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name  | Type                 | Mandatory| Description      |
| -------- | --------------------- | ---- | ---------- |
| callback | AsyncCallback\<void\> | Yes  | Callback used to return the result.|


**Example**

```
let tcp = socket.constructTCPSocketInstance();
tcp.close(err => {
  if (err) {
	console.log('close fail');
	return;
  }
  console.log('close success');
})
```


### close

close\(\): Promise<void\>

Closes a TCPSocket connection. This API uses a promise to return the result.

**Required permission**: ohos.permission.INTERNET

**System capability**: SystemCapability.Communication.NetStack

**Return Value**

| Type           | Description                                      |
| :-------------- | :----------------------------------------- |
| Promise\<void\> | Promise used to return the result.|

**Example**

```
let tcp = socket.constructTCPSocketInstance();
let promise = tcp.close();
promise.then(() => {
  console.log('close success');
}).catch(err => {
  console.log('close fail');
});
```


### getRemoteAddress

getRemoteAddress\(callback: AsyncCallback<NetAddress\>\): void

Obtains the remote address of a TCPSocket connection. This API uses an asynchronous callback to return the result.

>![](public_sys-resources/icon-note.gif) **NOTE:**
>This API can be called only after [connect](#connect) is successfully called.

**Required permission**: ohos.permission.INTERNET

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name  | Type                                             | Mandatory| Description      |
| -------- | ------------------------------------------------- | ---- | ---------- |
| callback | AsyncCallback<[NetAddress](#netaddress)> | Yes  | Callback used to return the result.|

**Example**

```
let tcp = socket.constructTCPSocketInstance();
let promise = tcp.connect({ address: {address: '192.168.xx.xxx', port: xxxx, family: 1} , timeout: 6000});
promise.then(() => {
  console.log('connect success');
  tcp.getRemoteAddress((err, data) => {
	if (err) {
	  console.log('getRemoteAddressfail');
	  return;
	}
	console.log('getRemoteAddresssuccess:' + JSON.stringify(data));
  })
}).catch(err => {
  console.log('connect fail');
});
```


### getRemoteAddress

getRemoteAddress\(\): Promise<NetAddress\>

Obtains the remote address of a TCPSocket connection. This API uses a promise to return the result.

>![](public_sys-resources/icon-note.gif) **NOTE:**
>This API can be called only after [connect](#connect) is successfully called.

**Required permission**: ohos.permission.INTERNET

**System capability**: SystemCapability.Communication.NetStack

**Return Value**

| Type                                       | Description                                       |
| :------------------------------------------ | :------------------------------------------ |
| Promise<[NetAddress](#netaddress)> | Promise used to return the result.|

**Example**

```
let tcp = socket.constructTCPSocketInstance();
let promise1 = tcp.connect({ address: {address: '192.168.xx.xxx', port: xxxx, family: 1} , timeout: 6000});
promise1.then(() => {
  console.log('connect success');
  let promise2 = tcp.getRemoteAddress();
  promise2.then(() => {
	console.log('getRemoteAddress success:' + JSON.stringify(data));
  }).catch(err => {
	console.log('getRemoteAddressfail');
  });
}).catch(err => {
  console.log('connect fail');
});
```


### getState

getState\(callback: AsyncCallback<SocketStateBase\>\): void

Obtains the status of the TCPSocket connection. This API uses an asynchronous callback to return the result.

>![](public_sys-resources/icon-note.gif) **NOTE:**
>This API can be called only after [bind](#bind) or [connect](#connect) is successfully called.

**Required permission**: ohos.permission.INTERNET

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name  | Type                                                  | Mandatory| Description      |
| -------- | ------------------------------------------------------ | ---- | ---------- |
| callback | AsyncCallback<[SocketStateBase](#socketstatebase)> | Yes  | Callback used to return the result.|


**Example**

```
let tcp = socket.constructTCPSocketInstance();
let promise = tcp.connect({ address: {address: '192.168.xx.xxx', port: xxxx, family: 1} , timeout: 6000});
promise.then(() => {
  console.log('connect success');
  tcp.getState((err, data) => {
	if (err) {
	  console.log('getState fail');
	  return;
	}
	console.log('getState success:' + JSON.stringify(data));
  });
}).catch(err => {
  console.log('connect fail');
});
```


### getState

getState\(\): Promise<SocketStateBase\>

Obtains the status of the TCPSocket connection. This API uses a promise to return the result.

>![](public_sys-resources/icon-note.gif) **NOTE:**
>This API can be called only after [bind](#bind) or [connect](#connect) is successfully called.

**Required permission**: ohos.permission.INTERNET

**System capability**: SystemCapability.Communication.NetStack

**Return Value**

| Type                                            | Description                                      |
| :----------------------------------------------- | :----------------------------------------- |
| Promise<[SocketStateBase](#socketstatebase)> | Promise used to return the result.|


**Example**

```
let tcp = socket.constructTCPSocketInstance();
let promise = tcp.connect({ address: {address: '192.168.xx.xxx', port: xxxx, family: 1} , timeout: 6000});
promise.then(() => {
  console.log('connect success');
  let promise1 = tcp.getState();
  promise1.then(() => {
	console.log('getState success:' + JSON.stringify(data));
  }).catch(err => {
	console.log('getState fail');
  });
}).catch(err => {
  console.log('connect fail');
});
```


### setExtraOptions

setExtraOptions\(options: TCPExtraOptions, callback: AsyncCallback<void\>\): void

Sets other properties of the TCPSocket connection. This API uses an asynchronous callback to return the result.

>![](public_sys-resources/icon-note.gif) **NOTE:**
>This API can be called only after [bind](#bind) or [connect](#connect) is successfully called.

**Required permission**: ohos.permission.INTERNET

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name  | Type                                     | Mandatory| Description                                                        |
| -------- | ----------------------------------------- | ---- | ------------------------------------------------------------ |
| options  | [TCPExtraOptions](#tcpextraoptions) | Yes  | Other properties of the TCPSocket connection. For details, see [TCPExtraOptions](#tcpextraoptions).|
| callback | AsyncCallback\<void\>                     | Yes  | Callback used to return the result.                                                  |

**Example**

```
let tcp = socket.constructTCPSocketInstance();
let promise = tcp.connect({ address: {address: '192.168.xx.xxx', port: xxxx, family: 1} , timeout: 6000});
promise.then(() => {
  console.log('connect success');
  tcp.setExtraOptions({
	keepAlive: true,
	OOBInline: true,
	TCPNoDelay: true,
	socketLinger: { on:true, linger:10 },
	receiveBufferSize: 1000,
	sendBufferSize: 1000,
	reuseAddress: true,
	socketTimeout: 3000,
  },err => {
	if (err) {
	  console.log('setExtraOptions fail');
	  return;
	}
	console.log('setExtraOptions success');
  });
}).catch(err => {
  console.log('connect fail');
});
```


### setExtraOptions

setExtraOptions\(options: TCPExtraOptions\): Promise<void\>

Sets other properties of the TCPSocket connection. This API uses a promise to return the result.

>![](public_sys-resources/icon-note.gif) **NOTE:**
>This API can be called only after [bind](#bind) or [connect](#connect) is successfully called.

**Required permission**: ohos.permission.INTERNET

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name | Type                                     | Mandatory| Description                                                        |
| ------- | ----------------------------------------- | ---- | ------------------------------------------------------------ |
| options | [TCPExtraOptions](#tcpextraoptions) | Yes  | Other properties of the TCPSocket connection. For details, see [TCPExtraOptions](#tcpextraoptions).|

**Return Value**

| Type           | Description                                                |
| :-------------- | :--------------------------------------------------- |
| Promise\<void\> | Promise used to return the result.|


**Example**

```
let tcp = socket.constructTCPSocketInstance();
let promise = tcp.connect({ address: {address: '192.168.xx.xxx', port: xxxx, family: 1} , timeout: 6000});
promise.then(() => {
  console.log('connect success');
  let promise1 = tcp.setExtraOptions({
	keepAlive: true,
	OOBInline: true,
	TCPNoDelay: true,
	socketLinger: { on:true, linger:10 },
	receiveBufferSize: 1000,
	sendBufferSize: 1000,
	reuseAddress: true,
	socketTimeout: 3000,
  });
  promise1.then(() => {
	console.log('setExtraOptions success');
  }).catch(err => {
	console.log('setExtraOptions fail');
  });
}).catch(err => {
  console.log('connect fail');
});
```


### on\('message'\)

on\(type: 'message', callback: Callback<\{message: ArrayBuffer, remoteInfo: SocketRemoteInfo\}\>\): void

Enables listening for message receiving events of the TCPSocket connection. This API uses an asynchronous callback to return the result.

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name  | Type                                                        | Mandatory| Description                                     |
| -------- | ------------------------------------------------------------ | ---- | ----------------------------------------- |
| type     | string                                                       | Yes  | Event type. <br />**message**: message receiving event|
| callback | Callback<{message: ArrayBuffer, remoteInfo: [SocketRemoteInfo](#socketremoteinfo)}> | Yes  | Callback used to return the result.                               |

**Example**

```
let tcp = socket.constructTCPSocketInstance();
tcp.on('message', value => {
	console.log("on message, message:" + value.message + ", remoteInfo:" + value.remoteInfo)
});
```


### off\('message'\)

off\(type: 'message', callback?: Callback<\{message: ArrayBuffer, remoteInfo: SocketRemoteInfo\}\>\): void

Disables listening for message receiving events of the TCPSocket connection. This API uses an asynchronous callback to return the result.

>![](public_sys-resources/icon-note.gif) **NOTE:**
>You can pass the callback of the **on** function if you want to cancel listening for a certain type of event. If you do not pass the callback, you will cancel listening for all events.

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name  | Type                                                        | Mandatory| Description                                     |
| -------- | ------------------------------------------------------------ | ---- | ----------------------------------------- |
| type     | string                                                       | Yes  | Event type. <br />**message**: message receiving event|
| callback | Callback<{message: ArrayBuffer, remoteInfo: [SocketRemoteInfo](#socketremoteinfo)}> | No  | Callback used to return the result.                               |

**Example**

```
let tcp = socket.constructTCPSocketInstance();
let callback = value =>{
	console.log("on message, message:" + value.message + ", remoteInfo:" + value.remoteInfo);
}
tcp.on('message', callback);
// You can pass the callback of the on function to cancel listening for a certain type of callback. If you do not pass the callback, you will cancel listening for all callbacks.
tcp.off('message', callback);
tcp.off('message');
```


### on\('connect' | 'close'\)

on\(type: 'connect' | 'close', callback: Callback<void\>\): void

Enables listening for connection or close events of the TCPSocket connection. This API uses an asynchronous callback to return the result.

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name  | Type            | Mandatory| Description                                                        |
| -------- | ---------------- | ---- | ------------------------------------------------------------ |
| type     | string           | Yes  | Event type.<br>- **connect**: connection event<br>- **close**: close event|
| callback | Callback\<void\> | Yes  | Callback used to return the result.                                                  |


**Example**

```
let tcp = socket.constructTCPSocketInstance();
tcp.on('connect', () => {
	console.log("on connect success")
});
tcp.on('close', data => {
	console.log("on close success")
});
```


### off\('connect' | 'close'\)

off\(type: 'connect' | 'close', callback?: Callback<void\>\): void

Disables listening for connection or close events of the TCPSocket connection. This API uses an asynchronous callback to return the result.

>![](public_sys-resources/icon-note.gif) **NOTE:**
>You can pass the callback of the **on** function if you want to cancel listening for a certain type of event. If you do not pass the callback, you will cancel listening for all events.

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name  | Type            | Mandatory| Description                                                        |
| -------- | ---------------- | ---- | ------------------------------------------------------------ |
| type     | string           | Yes  | Event type.<br>- **connect**: connection event<br>- **close**: close event|
| callback | Callback\<void\> | No  | Callback used to return the result.                                                  |

**Example**

```
let tcp = socket.constructTCPSocketInstance();
let callback1 = () =>{
	console.log("on connect success");
}
tcp.on('connect', callback1);
// You can pass the callback of the on function to cancel listening for a certain type of callback. If you do not pass the callback, you will cancel listening for all callbacks.
tcp.off('connect', callback1);
tcp.off('connect');
let callback2 = () =>{
	console.log("on close success");
}
tcp.on('close', callback2);
// You can pass the callback of the on function to cancel listening for a certain type of callback. If you do not pass the callback, you will cancel listening for all callbacks.
tcp.off('close', callback2);
tcp.off('close');
```


### on\('error'\)

on\(type: 'error', callback: ErrorCallback\): void

Enables listening for error events of the TCPSocket connection. This API uses an asynchronous callback to return the result.

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name  | Type         | Mandatory| Description                                |
| -------- | ------------- | ---- | ------------------------------------ |
| type     | string        | Yes  | Event type. <br />**error**: error event|
| callback | ErrorCallback | Yes  | Callback used to return the result.                          |

**Example**

```
let tcp = socket.constructTCPSocketInstance();
tcp.on('error', err => {
	console.log("on error, err:" + JSON.stringify(err))
});
```


### off\('error'\)

off\(type: 'error', callback?: ErrorCallback\): void

Disables listening for error events of the TCPSocket connection. This API uses an asynchronous callback to return the result.

>![](public_sys-resources/icon-note.gif) **NOTE:**
>You can pass the callback of the **on** function if you want to cancel listening for a certain type of event. If you do not pass the callback, you will cancel listening for all events.

**System capability**: SystemCapability.Communication.NetStack

**Parameters**

| Name  | Type         | Mandatory| Description                                |
| -------- | ------------- | ---- | ------------------------------------ |
| type     | string        | Yes  | Event type. <br />**error**: error event|
| callback | ErrorCallback | No  | Callback used to return the result.                          |

**Example**

```
let tcp = socket.constructTCPSocketInstance();
let callback = err =>{
	console.log("on error, err:" + JSON.stringify(err));
}
tcp.on('error', callback);
// You can pass the callback of the on function to cancel listening for a certain type of callback. If you do not pass the callback, you will cancel listening for all callbacks.
tcp.off('error', callback);
tcp.off('error');
```


## TCPConnectOptions

Defines TCPSocket connection parameters.

**System capability**: SystemCapability.Communication.NetStack

| Name | Type                              | Mandatory| Description                      |
| ------- | ---------------------------------- | ---- | -------------------------- |
| address | [NetAddress](#netaddress) | Yes  | Bound IP address and port number.      |
| timeout | number                             | No  | Timeout duration of the TCPSocket connection, in ms.|

## TCPSendOptions

Defines the parameters for sending data over the TCPSocket connection.

**System capability**: SystemCapability.Communication.NetStack

| Name  | Type  | Mandatory| Description                                                        |
| -------- | ------ | ---- | ------------------------------------------------------------ |
| data     | string | Yes  | Data to send.                                                |
| encoding | string | No  | Character encoding format. The options are as follows: **UTF-8**, **UTF-16BE**, **UTF-16LE**, **UTF-16**, **US-AECII**, and **ISO-8859-1**. The default value is **UTF-8**.|

## TCPExtraOptions

Defines other properties of the TCPSocket connection.

**System capability**: SystemCapability.Communication.NetStack

| Name           | Type   | Mandatory| Description                                                        |
| ----------------- | ------- | ---- | ------------------------------------------------------------ |
| keepAlive         | boolean | No  | Whether to keep the connection alive. The default value is **false**.                                 |
| OOBInline         | boolean | No  | Whether to enable OOBInline. The default value is **false**.                                |
| TCPNoDelay        | boolean | No  | Whether to enable no-delay on the TCPSocket connection. The default value is **false**.                      |
| socketLinger      | Object  | Yes  | Socket linger.<br>- **on**: whether to enable socket linger. The value true means to enable socket linger and false means the opposite.<br>- **linger**: linger time, in ms. The value ranges from **0** to **65535**.<br>Specify this parameter only when **on** is set to **true**.|
| receiveBufferSize | number  | No  | Size of the receive buffer, in bytes.                              |
| sendBufferSize    | number  | No  | Size of the send buffer, in bytes.                              |
| reuseAddress      | boolean | No  | Whether to reuse addresses. The default value is **false**.                                 |
| socketTimeout     | number  | No  | Timeout duration of the TCPSocket connection, in ms.                            |