# DSoftBus

## Introduction

There are various ways of communication (such as Wi-Fi and Bluetooth) between devices. The difference in the usage of these communication methods may lead to communication issues. In addition, there are many challenges in converging and sharing communication links between devices and handling conflicts.

DSoftBus implements unified distributed communications between near-field devices and provides APIs for device discovery, connections, networking, and data transmission, regardless of the link type. It stands out with the following capabilities:

-   Implements discovery and connections of devices in various communication modes, such as WLAN and Bluetooth.
-   Performs unified device networking and topology management, and provides device information for data transmission.
-   Sets up channels for transmitting messages, bytes, streams, and files.

You can use the APIs provided by DSoftBus to implement fast communication between devices without caring about the communication details, which accelerates deployment and running of services across platforms.

## Architecture

![](figures/dsoftbus-architecture.png)

**Figure 1** DSoftBus architecture

## Directory Structure

The DSoftBus directory structure is as follows:

```text
//foundation/communication/dsoftbus
├── adapter               # Adaptation code
├── components            # Dependent components
├── core                  # Core code
│   ├── adapter           # Adaptation code
│   ├── authentication    # Code for authentication
│   ├── bus_center        # Code for networking
│   ├── common            # Common code
│   ├── connection        # Code for device connections
│   ├── discovery         # Code for device discovery
│   ├── frame             # Framework code
│   └── transmission      # Code for data transmission
├── interfaces            # External APIs
├── sdk                   # SDK
│   ├── bus_center        # Networking
│   ├── discovery         # Device discovery
│   ├── frame             # Framework
│   └── transmission      # Transmission
├── tests                 # Test code
└── tools                 # Tools
```

## Constraints

-   Connections can be set up only between the devices in the same LAN or between near-field devices.
-   Before setting up a connection between two devices, you must bind devices. For details, see [Security](https://gitee.com/openharmony/docs/blob/master/en/readme/Security.md).
-   After data transmission is complete, the service needs to close the session to release resources.

## Usage

>**NOTE**
>
>The permissions ohos.permission.DISTRIBUTED_DATASYNC and ohos.permission.DISTRIBUTED_SOFTBUS_CENTER are required for remote procedure calls (RPCs) across devices.

### Device Discovery

-   **Publishing process**

1.  Call **PublishLNN()** to publish application information across a network.

    ```C
    // Callback used to return the publish result.
    typedef struct {
        /** Callback for publish result */
        void (*OnPublishResult)(int publishId, PublishResult reason);
    } IPublishCb;

    // Information to publish.
    typedef struct {
        int publishId;                 // Publish ID.
        DiscoverMode mode;             // Discovery mode.
        ExchangeMedium medium;         // Medium to use.
        ExchangeFreq freq;             // Frequency to use.
        const char *capability;        // Capability of the device to discover.
        unsigned char *capabilityData; // Custom data to publish.
        unsigned int dataLen;          // Data length.
        bool ranging;                  // Whether ranging is required.
    } PublishInfo;

    // Publish information.
    int32_t PublishLNN(const char *pkgName, const PublishInfo *info, const IPublishCb *cb);
    ```

2.  Call **StopPublishLNN** to stop publishing information when it is not required.

    ```C
    // Stop publishing a service.
    int32_t StopPublishLNN(const char *pkgName, int32_t publishId);
    ```


-   **Discovery process**

1. Call **RefreshLNN()** to discover devices with the specified capability.

   ```C
   // Callbacks for device discovery.
   typedef struct {
       /** Callback to be invoked when a device is found. */
       void (*OnDeviceFound)(const DeviceInfo *device);
       /** Callback for a subscription result. */
       void (*OnDiscoverResult)(int32_t refreshId, RefreshResult reason);
   } IRefreshCallback;

   // Start device discovery.
   int32_t RefreshLNN(const char *pkgName, const SubscribeInfo *info, const IRefreshCallback *cb);
   ```

   DSoftBus notifies the service of the device information via a callback once a device is found.

3.  Call **StopRefreshLNN()** to stop device discovery.

    ```C
    // Stop the discovery.
    int32_t StopRefreshLNN(const char *pkgName, int32_t refreshId);
    ```

### Networking

1.  Initiate a request for connection with the target device address and a callback used to return the connection result.

    ```C
    // Address of the target device to connect to.
    typedef struct {
        ConnectionAddrType type;
        union {
            struct BrAddr {
                char brMac[BT_MAC_LEN];
            } br;
            struct BleAddr {
                char bleMac[BT_MAC_LEN];
                uint8_t udidHash[UDID_HASH_LEN];
            } ble;
            struct IpAddr {
                char ip[IP_STR_MAX_LEN];
                uint16_t port;
            } ip;
        } info;
        char peerUid[MAX_ACCOUNT_HASH_LEN];
    } ConnectionAddr;

    // Address type.
    typedef enum {
        CONNECTION_ADDR_WLAN = 0,
        CONNECTION_ADDR_BR,
        CONNECTION_ADDR_BLE,
        CONNECTION_ADDR_ETH,
        CONNECTION_ADDR_MAX
    } ConnectionAddrType;

    // Callback used to return the connection result.
    typedef void (*OnJoinLNNResult)(ConnectionAddr *addr, const char *networkId, int32_t retCode);

    // Initiate a connection request.
    int32_t JoinLNN(const char *pkgName, ConnectionAddr *target, OnJoinLNNResult cb);
    ```

2. Wait for the connection result.

   If **JoinLNN()** returns success, DSoftBus accepts the connection request and notifies the service of the connection result through the callback. The **addr** parameter in the callback matches the **target** parameter in **JoinLNN()**. If **retCode** in the callback is **0**, the connection is successful. In this case, the value of **networkId** is valid and will be used in the data transmission and disconnection APIs. If the value of **retCode** is not **0**, the connection fails, and the value of **networkId** is invalid.

3. Transmit data using the related APIs.

4. Initiate a disconnection request with the **networkId** and a callback for returing the result.

   ```C
   // Callback used to return the disconnection result.
   typedef void (*OnLeaveLNNResult)(const char *networkId, int32_t retCode);

   // Initiate a disconnection request.
   int32_t LeaveLNN(const char *pkgName, const char *networkId, OnLeaveLNNResult cb);
   ```

5. Wait until the disconnection is complete.

   The **networkId** parameter in **OnLeaveLNNResult()** matches **networkId** in **LeaveLNN()**. If **retCode** in the callback is **0**, the disconnection is successful; otherwise, the disconnection fails. If the disconnection is successful, **networkId** becomes invalid and can no longer be used.

6. Register and unregister callbacks for device state changes.

   ```C
   // Device state events.
   #define EVENT_NODE_STATE_ONLINE 0x1
   #define EVENT_NODE_STATE_OFFLINE 0x02
   #define EVENT_NODE_STATE_INFO_CHANGED 0x04
   #define EVENT_NODE_STATUS_CHANGED 0x08
   #define EVENT_NODE_STATE_MASK 0xF

   // Device information.
   typedef struct {
       char networkId[NETWORK_ID_BUF_LEN];
       char deviceName[DEVICE_NAME_BUF_LEN];
       uint16_t deviceTypeId;
   } NodeBasicInfo;

   // Device state event callbacks.
   typedef struct {
       uint32_t events; // Networking event mask.
       void (*onNodeOnline)(NodeBasicInfo *info);   // Called when the device gets online.
       void (*onNodeOffline)(NodeBasicInfo *info);  // Called when the device gets offline.
       void (*onNodeBasicInfoChanged)(NodeBasicInfoType type, NodeBasicInfo *info); // Called when the device information changes.
       void (*onNodeStatusChanged)(NodeStatusType type, NodeStatus *status); // Called when the device running status changes.
   } INodeStateCb;

   // Register a callback for device state events.
   int32_t RegNodeDeviceStateCb(const char *pkgName, INodeStateCb *callback);

   // Unregister a callback for device state events.
   int32_t UnregNodeDeviceStateCb(INodeStateCb *callback);
   ```

### Transmission

1.  Create a **Socket** instance.

    ```C
    typedef struct {
        char *name;                 // Local socket name.
        char *peerName;             // Peer socket name.
        char *peerNetworkId;        // Peer network ID.
        char *pkgName;              // Bundle name of the caller.
        TransDataType dataType;     // Type of the data to be transmitted.
    } SocketInfo;

    // Create sockets.
    int32_t Socket(SocketInfo info);
    ```

2.  Start listening for the socket on the server, and bind the socket on the client.

    ```C
    // Socket callbacks.
    typedef struct {
        void (*OnBind)(int32_t socket, PeerSocketInfo info);
        void (*OnShutdown)(int32_t socket, ShutdownReason reason);
        void (*OnBytes)(int32_t socket, const void *data, uint32_t dataLen);
        void (*OnMessage)(int32_t socket, const void *data, uint32_t dataLen);
        void (*OnStream)(int32_t socket, const StreamData *data, const StreamData *ext, const StreamFrameInfo *param);
        void (*OnFile)(int32_t socket, FileEvent *event);
        void (*OnQos)(int32_t socket, QoSEvent eventId, const QosTV *qos, uint32_t qosCount);
        void (*OnError)(int32_t socket, int32_t errCode);
        void (*OnBytesSent)(int32_t socket, uint32_t dataSeq, int32_t errCode);
    } ISocketListener;

    typedef enum {
        QOS_TYPE_MIN_BW,            // Minimum bandwidth.
        QOS_TYPE_MAX_WAIT_TIMEOUT,  // Bind timeout.
        QOS_TYPE_MIN_LATENCY,       // Minimum connection latency.
        QOS_TYPE_RTT_LEVEL,         // Round-trip time (RTT) level.
        QOS_TYPE_MAX_BUFFER,        // Maximum buffer (reserved).
        QOS_TYPE_FIRST_PACKAGE,     // Size of the first packet (reserved).
        QOS_TYPE_MAX_IDLE_TIMEOUT,  // Maximum idle time.
        QOS_TYPE_TRANS_RELIABILITY, // Transmission reliability (reserved).
        QOS_TYPE_BUTT,
    } QosType;

    typedef struct {
        QosType qos;
        int32_t value;
    } QosTV;

    // Start listening for the socket on the server.
    int32_t Listen(int32_t socket, const QosTV qos[], uint32_t qosCount, const ISocketListener *listener);

    // Bind the socket on the client.
    int32_t Bind(int32_t socket, const QosTV qos[], uint32_t qosCount, const ISocketListener *listener);
    ```

4. Send data to the peer device through the socket.

    ```C
    // Send bytes.
    int32_t SendBytes(int32_t socket, const void *data, uint32_t len);
    // Async Send bytes. dataSeq indicates the unique seq number of the packet to be sent, which cannot be zero.
    int32_t SendBytesAsync(int32_t socket, uint32_t dataSeq, const void *data, uint32_t len);
    // Send messages.
    int32_t SendMessage(int32_t socket, const void *data, uint32_t len);
    // Send a stream.
    int32_t SendStream(int32_t socket, const StreamData *data, const StreamData *ext, const StreamFrameInfo *param);
    // Send a file.
    int32_t SendFile(int32_t socket, const char *sFileList[], const char *dFileList[], uint32_t fileCnt);
    ```

4. Shut down a socket.

    ```C
    // Shut down a socket.
    void Shutdown(int32_t socket);
    ```

### Device Management


-   Select Wi-Fi keepalive mode.

Call **ShiftLNNGear** on the DSoftBus client to invoke the server **ShiftLNNGear** through an IPC interface. The policy management module adjusts the **keepalive** property of the TCP persistent connection based on the specified policy.

```C
typedef struct {
    ModeCycle cycle;             // Keepalive probe interval.
    ModeDuration duration;       // Heartbeat mode duration.
    bool wakeupFlag;             // Whether the heartbeat signal wakes up the peer device.
    ModeAction action;           // Action to be taken during the keepalive process.
} GearMode;

typedef enum {
    HIGH_FREQ_CYCLE = 30,         // Heartbeat interval 30s.
    MID_FREQ_CYCLE = 60,          // Heartbeat interval 60s.
    LOW_FREQ_CYCLE = 5 * 60,      // Heartbeat interval 5 minutes.
    DEFAULT_FREQ_CYCLE = 10 * 60, // Heartbeat interval 10 minutes.
} ModeCycle;

// Adjust the keepalive parameters of a TCP persistent connection based on the specified gear mode.
int32_t ShiftLNNGear(const char *pkgName, const char *callerId, const char *targetNetworkId, const GearMode *mode);
```

The TCP keepalive duration varies, depending on **ModeCycle**.

```C
HIGH_FREQ_CYCLE = 30, // The TCP keepalive duration is within 40s.
MID_FREQ_CYCLE = 60, // The TCP keepalive duration is within 70s.
LOW_FREQ_CYCLE = 5 x 60, // The TCP keepalive duration is within 315s.
DEFAULT_FREQ_CYCLE = 10 x 60, // The TCP keepalive duration is within 615s.
```

## Repositories Involved

[DSoftBus](https://gitee.com/openharmony/docs/blob/master/en/readme/dsoftbus.md)

**communication_dsoftbus**

[communication_bluetooth](https://gitee.com/openharmony/communication_bluetooth)

[communication_ipc](https://gitee.com/openharmony/communication_ipc)

[communication_wifi](https://gitee.com/openharmony/communication_wifi)

# 分布式软总线组件<a name="ZH-CN_TOPIC_0000001103650648"></a>

- [分布式软总线组件<a name="ZH-CN_TOPIC_0000001103650648"></a>](#分布式软总线组件)
  - [简介<a name="section13587125816351"></a>](#简介)
  - [系统架构<a name="section13587185873516"></a>](#系统架构)
  - [目录<a name="section161941989596"></a>](#目录)
  - [约束<a name="section119744591305"></a>](#约束)
  - [说明<a name="section1312121216216"></a>](#说明)
    - [使用说明<a name="section1698318421816"></a>](#使用说明)
  - [相关仓<a name="section1371113476307"></a>](#相关仓)

## 简介<a name="section13587125816351"></a>

现实中多设备间通信方式多种多样\(WIFI、蓝牙等\)，不同的通信方式使用差异大，导致通信问题多；同时还面临设备间通信链路的融合共享和冲突无法处理等挑战。分布式软总线实现近场设备间统一的分布式通信管理能力，提供不区分链路的设备间发现连接、组网和传输能力，主要功能如下：

-   发现连接：提供基于Wifi、蓝牙等通信方式的设备发现连接能力。
-   设备组网：提供统一的设备组网和拓扑管理能力，为数据传输提供已组网设备信息。
-   数据传输：提供数据传输通道，支持消息、字节、流、文件的数据传输能力。

业务方通过使用分布式软总线提供的API实现设备间的高速通信，不用关心通信细节，进而实现业务平台的高效部署与运行能力。

## 系统架构<a name="section13587185873516"></a>

![](figures/dsoftbus-architecture_zh.png)
**图 1**  分布式软总线组件架构图<a name="fig4460722185514"></a>

## 目录<a name="section161941989596"></a>

分布式软总线组件主要代码目录结构如下：

```text
//foundation/communication/dsoftbus
├── adapter               # 适配层代码
├── components            # 依赖组件代码
├── core                  # 核心代码
│   ├── adapter           # 适配层代码
│   ├── authentication    # 认证代码
│   ├── bus_center        # 组网代码
│   ├── common            # 通用代码
│   ├── connection        # 连接代码
│   ├── discovery         # 发现代码
│   ├── frame             # 框架代码
│   └── transmission      # 传输代码
├── interfaces            # 对外接口代码
├── sdk                   # 运行业务进程代码
│   ├── bus_center        # 组网代码
│   ├── discovery         # 发现代码
│   ├── frame             # 框架代码
│   └── transmission      # 传输代码
├── tests                 # 测试代码
└── tools                 # 工具代码
```

## 约束<a name="section119744591305"></a>

-   组网设备需在同一局域网中 或者 距离相近的近场设备间。
-   组网之前，需先完成设备绑定，绑定流程参见[安全基础能力子系统](https://gitee.com/openharmony/docs/blob/master/zh-cn/readme/%E5%AE%89%E5%85%A8%E5%9F%BA%E7%A1%80%E8%83%BD%E5%8A%9B%E5%AD%90%E7%B3%BB%E7%BB%9F.md)中说明。
-   传输完成数据收发之后，业务要主动关闭会话，释放资源。

## 说明<a name="section1312121216216"></a>

### 使用说明<a name="section1698318421816"></a>

>**须知：**
>使用跨设备通信时，必须添加权限`ohos.permission.DISTRIBUTED_DATASYNC`和`ohos.permission.DISTRIBUTED_SOFTBUS_CENTER`，该权限类型为 _**dangerous**_ 。

**1、发现**

-   **发布流程**

1.  上层应用需要对外发布自身能力时，调用服务发布接口发布自身能力。

    ```C
    // 发布回调
    typedef struct {
        /** Callback for publish result */
        void (*OnPublishResult)(int publishId, PublishResult reason);
    } IPublishCb;

    // 发布信息
    typedef struct {
        int publishId;                  // 发布消息Id
        DiscoverMode mode;              // 发布模式
        ExchangeMedium medium;          // 发布媒介
        ExchangeFreq freq;              // 发布频率
        const char *capability;         // 被发现设备需要具备的能力
        unsigned char *capabilityData;  // 业务发布的自定义数据
        unsigned int dataLen;           // 数据长度
        bool ranging;                   // 是否测距
    } PublishInfo;

    // 发布服务
    int32_t PublishLNN(const char *pkgName, const PublishInfo *info, const IPublishCb *cb);
    ```

2.  上层应用不再需要对外发布自身能力时，调用StopPublishLNN接口注销服务。

    ```C
    // 注销服务
    int32_t StopPublishLNN(const char *pkgName, int32_t publishId);
    ```


-   **发现流程**

1.  上层应用需要发现特定能力设备时，调用发现接口启动发现。

    ```C
    // 发现回调
    typedef struct {
        /** Callback that is invoked when a device is found */
        void (*OnDeviceFound)(const DeviceInfo *device);
        /** Callback for a subscription result */
        void (*OnDiscoverResult)(int32_t refreshId, RefreshResult reason);
    } IRefreshCallback;

    // 发现服务
    int32_t RefreshLNN(const char *pkgName, const SubscribeInfo *info, const IRefreshCallback *cb);
    ```

2.  当软总线发现到设备时，通过回调接口通知业务所发现的设备信息。
3.  上层应用不再需要发现时，调用StopRefreshLNN接口停止设备发现。

    ```C
    // 停止发现
    int32_t StopRefreshLNN(const char *pkgName, int32_t refreshId);
    ```

**2、组网**

1.  发起组网请求，携带组网连接地址信息，并且提供组网执行结果回调函数。

    ```C
    // 组网连接地址
    typedef struct {
        ConnectionAddrType type;
        union {
            struct BrAddr {
                char brMac[BT_MAC_LEN];
            } br;
            struct BleAddr {
                char bleMac[BT_MAC_LEN];
                uint8_t udidHash[UDID_HASH_LEN];
            } ble;
            struct IpAddr {
                char ip[IP_STR_MAX_LEN];
                uint16_t port;
            } ip;
        } info;
        char peerUid[MAX_ACCOUNT_HASH_LEN];
    } ConnectionAddr;

    // 组网连接地址类型
    typedef enum {
        CONNECTION_ADDR_WLAN = 0,
        CONNECTION_ADDR_BR,
        CONNECTION_ADDR_BLE,
        CONNECTION_ADDR_ETH,
        CONNECTION_ADDR_MAX
    } ConnectionAddrType;

    // 组网请求执行结果回调
    typedef void (*OnJoinLNNResult)(ConnectionAddr *addr, const char *networkId, int32_t retCode);

    // 发起组网请求
    int32_t JoinLNN(const char *pkgName, ConnectionAddr *target, OnJoinLNNResult cb);
    ```

2.  等待组网结果，JoinLNN\(\)返回成功表示软总线接受了组网请求，组网结果通过回调函数通知业务；组网回调函数中addr参数内容和JoinLNN\(\)的入参互相匹配；retCode如果为0，表示组网成功，此时networkId为有效值，后续传输、退网等接口均需使用该参数；retCode如果不为0，表示组网失败，此时networkId为无效值。
3.  使用传输相关接口进行数据传输。
4.  发送退网请求，携带组网成功后返回的networkId，并且提供退网执行结果回调。

    ```C
    // 退网执行结果回调
    typedef void (*OnLeaveLNNResult)(const char *networkId, int32_t retCode);

    // 退网请求
    int32_t LeaveLNN(const char *pkgName, const char *networkId, OnLeaveLNNResult cb);
    ```

5.  等待退网完成，OnLeaveLNNResult\(\)的networkId和退网请求接口中的networkId互相匹配；retCode为0表示退网成功，否则退网失败。退网成功后，networkId变为无效值，后续不应该被继续使用。
6.  使用节点（即设备）注册和注销接口，监听网络中节点状态变化等事件。

    ```C
    // 事件掩码
    #define EVENT_NODE_STATE_ONLINE 0x1
    #define EVENT_NODE_STATE_OFFLINE 0x02
    #define EVENT_NODE_STATE_INFO_CHANGED 0x04
    #define EVENT_NODE_STATUS_CHANGED 0x08
    #define EVENT_NODE_STATE_MASK 0xF

    // 节点信息
    typedef struct {
        char networkId[NETWORK_ID_BUF_LEN];
        char deviceName[DEVICE_NAME_BUF_LEN];
        uint16_t deviceTypeId;
    } NodeBasicInfo;

    // 节点状态事件回调
    typedef struct {
        uint32_t events; // 组网事件掩码
        void (*onNodeOnline)(NodeBasicInfo *info);   // 节点上线事件回调
        void (*onNodeOffline)(NodeBasicInfo *info);  // 节点下线事件回调
        void (*onNodeBasicInfoChanged)(NodeBasicInfoType type, NodeBasicInfo *info); // 节点信息变化事件回调
        void (*onNodeStatusChanged)(NodeStatusType type, NodeStatus *status); // 设备运行状态变化事件回调
    } INodeStateCb;

    //  注册节点状态事件回调
    int32_t RegNodeDeviceStateCb(const char *pkgName, INodeStateCb *callback);

    // 注销节点状态事件回调
    int32_t UnregNodeDeviceStateCb(INodeStateCb *callback);
    ```

**3、传输**

1.  创建Socket。

    ```C
    typedef struct {
        char *name;                 // 本端Socket名称
        char *peerName;             // 对端Socket名称
        char *peerNetworkId;        // 对端Socket的网络ID
        char *pkgName;              // 调用者包名
        TransDataType dataType;     // 传输的数据类型，需要与发送方法一致
    } SocketInfo;

    // 创建Socket
    int32_t Socket(SocketInfo info);
    ```

2.  服务端启动监听，客户端进行绑定。

    ```C
    // Socket回调函数
    typedef struct {
        void (*OnBind)(int32_t socket, PeerSocketInfo info);
        void (*OnShutdown)(int32_t socket, ShutdownReason reason);
        void (*OnBytes)(int32_t socket, const void *data, uint32_t dataLen);
        void (*OnMessage)(int32_t socket, const void *data, uint32_t dataLen);
        void (*OnStream)(int32_t socket, const StreamData *data, const StreamData *ext, const StreamFrameInfo *param);
        void (*OnFile)(int32_t socket, FileEvent *event);
        void (*OnQos)(int32_t socket, QoSEvent eventId, const QosTV *qos, uint32_t qosCount);
        void (*OnError)(int32_t socket, int32_t errCode);
        void (*OnBytesSent)(int32_t socket, uint32_t dataSeq, int32_t errCode);
    } ISocketListener;

    typedef enum {
        QOS_TYPE_MIN_BW,            // 最小带宽
        QOS_TYPE_MAX_WAIT_TIMEOUT,  // Bind超时时间
        QOS_TYPE_MIN_LATENCY,       // 最小建链时延
        QOS_TYPE_RTT_LEVEL,         // 往返时间级别
        QOS_TYPE_MAX_BUFFER,        // 最大缓存(预留)
        QOS_TYPE_FIRST_PACKAGE,     // 首包大小(预留)
        QOS_TYPE_MAX_IDLE_TIMEOUT,  // 最大空闲时间
        QOS_TYPE_TRANS_RELIABILITY, // 传输可靠性(预留)
        QOS_TYPE_BUTT,
    } QosType;

    typedef struct {
        QosType qos;
        int32_t value;
    } QosTV;

    // 监听Socket，由服务端开启。
    int32_t Listen(int32_t socket, const QosTV qos[], uint32_t qosCount, const ISocketListener *listener);

    // 绑定Socket，由客户端开启。
    int32_t Bind(int32_t socket, const QosTV qos[], uint32_t qosCount, const ISocketListener *listener);
    ```

4. 通过Socket向对端设备发送数据。

    ```C
    // 发送字节数据
    int32_t SendBytes(int32_t socket, const void *data, uint32_t len);
    // 异步发送字节数据, dataSeq是无符号的不为0值的整数
    int32_t SendBytesAsync(int32_t socket, uint32_t dataSeq, const void *data, uint32_t len);
    // 发送消息数据
    int32_t SendMessage(int32_t socket, const void *data, uint32_t len);
    // 发送流数据
    int32_t SendStream(int32_t socket, const StreamData *data, const StreamData *ext, const StreamFrameInfo *param);
    // 发送文件
    int32_t SendFile(int32_t socket, const char *sFileList[], const char *dFileList[], uint32_t fileCnt);
    ```

5. 关闭Socket。

    ```C
    // 关闭Socket
    void Shutdown(int32_t socket);
    ```

**4、设备管理相关**

-   **选择Wi-Fi保活模式**

1.  业务在软总线客户端调用ShiftLNNGear，通过IPC接口调用到服务端ShiftLNNGear，策略管理模块按照策略对TCP长连接的keepalive属性进行调整。

    ```C
    typedef struct {
        ModeCycle cycle;              // 保活探测间隔
        ModeDuration duration;        // 心跳模式持续时间
        bool wakeupFlag;              // 是否心跳唤醒对端设备
        ModeAction action;            // 选择模式动作
    } GearMode;

    typedef enum {
        HIGH_FREQ_CYCLE = 30,         // 心跳间隔30s
        MID_FREQ_CYCLE = 60,          // 心跳间隔60s
        LOW_FREQ_CYCLE = 5 * 60,      // 心跳间隔5min
        DEFAULT_FREQ_CYCLE = 10 * 60, // 心跳间隔10min
    } ModeCycle;

    // 按照策略对TCP长连接的keepalive参数进行调整
    int32_t ShiftLNNGear(const char *pkgName, const char *callerId, const char *targetNetworkId, const GearMode *mode);
    ```

2.  业务指定不同的保活探测间隔，对应不同的TCP保活时长。

    ```C
    HIGH_FREQ_CYCLE = 30，代表TCP保活时长在40s以内；
    MID_FREQ_CYCLE = 60，代表TCP保活时长在70s以内；
    LOW_FREQ_CYCLE = 5*60，代表TCP保活时长在315s以内；
    DEFAULT_FREQ_CYCLE = 10*60，代表TCP保活时长在615s以内。
    ```

## 相关仓<a name="section1371113476307"></a>

[分布式软总线子系统](https://gitee.com/openharmony/docs/blob/master/zh-cn/readme/%E5%88%86%E5%B8%83%E5%BC%8F%E8%BD%AF%E6%80%BB%E7%BA%BF%E5%AD%90%E7%B3%BB%E7%BB%9F.md)

**communication_dsoftbus**

[communication_bluetooth](https://gitee.com/openharmony/communication_bluetooth)

[communication_ipc](https://gitee.com/openharmony/communication_ipc)

[communication_wifi](https://gitee.com/openharmony/communication_wifi)