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头文件

#include "DMSAsyncApi.h"

创建客户端对象

#define ADDRESS     "tcp://mqttdms.aodianyun.com:1883"
#define CLIENTID    "Publisher0"
DMSAsync client;
//创建客户端对象,失败返回 NULL
client = DMSAsync_create(ADDRESS, CLIENTID);

设置回调函数

//成功返回 DMSASYNC_SUCCESS，失败返回 DMSASYNC_FAILURE
//第二个参数为传递给回调函数的context
DMSAsync_setCallbacks(client, client, connectionLost, messageArrived, deliveryComplete);

回调函数定义

int messageArrived(void *context, char *topicName, int topicLen, DMSAsync_message *message)
{
    printf("messageArrived-->%s:%.*s\n", topicName, message->payloadlen, (char*)message->payload);
    fflush(stdout);
    DMSAsync_freeMessage(&message);
    DMSAsync_free(topicName);
    return 1;
}
void connectionLost(void *context, char *cause)
{
    printf("connectionlost\n");
}
void deliveryComplete(void* context, DMSAsync_token token)
{
    printf("deliveryComplete\n");
}

连接服务器

#define PUB_KEY     "demo"
#define SUB_KEY     "demo"
int result;
//成功返回 DMSASYNC_SUCCESS，否则onFailure回调函数中返回错误代码
if ((result = DMSAsync_connect(client, PUB_KEY, SUB_KEY, onConnect, onConnectFailure, client)) != DMSASYNC_SUCCESS)
{
    printf("Failed to connect, return code %d\n", result);
    exit(-1);
}
...
void onConnect(void* context, DMSAsync_successData* response)
{
    printf("onConnect\n");
}
void onConnectFailure(void* context, DMSAsync_failureData* response)
{
    printf("onConnectFailure\n");
}

关注话题

#define TOPIC       "test"
DMSAsync_responseOptions subRespOpts = RespOptsInit(onSubscribe, onSubscribeFailure, client);
//成功返回 DMSASYNC_SUCCESS，否则返回错误代码
DMSAsync_subscribe(client, TOPIC, &subRespOpts);
//等待关注成功
DMSAsync_waitForCompletion(client,subRespOpts.token,10000);
...
void onSubscribe(void* context, DMSAsync_successData* response)
{
    printf("onSubscribe\n");
}
void onSubscribeFailure(void* context, DMSAsync_failureData* response)
{
    printf("onSubscribeFailure\n");
}

推送消息

#define TOPIC       "test"
#define PAYLOAD     "Hello World!C"
DMSAsync_responseOptions sendOpts = RespOptsInit(onSend, NULL, client);
//成功返回 DMSASYNC_SUCCESS，否则返回错误代码
DMSAsync_send(client, TOPIC, strlen(PAYLOAD), PAYLOAD, &sendOpts);
DMSAsync_waitForCompletion(client, sendOpts.token, 10000);
...
void onSend(void* context, DMSAsync_successData* response)
{
    printf("onSend-->Message with token value %d delivery confirmed\n", response->token);
}

取消关注

#define TOPIC       "test"
DMSAsync_responseOptions unsubRespOpts = RespOptsInit(onUnsubscribe, onUnsubscribeFailure, client);
//成功返回 DMSASYNC_SUCCESS，否则返回错误代码
DMSAsync_unsubscribe(client, TOPIC, &unsubRespOpts);
//等待取消关注成功
DMSAsync_waitForCompletion(client, unsubRespOpts.token, 10000);
...
void onUnsubscribe(void* context, DMSAsync_successData* response)
{
    printf("onUnsubscribe\n");
}
void onUnsubscribeFailure(void* context, DMSAsync_failureData* response)
{
    printf("onUnSubscribeFailure\n");
}

断开连接

static int isDisconnected = 0;
DMSAsync_disconnectOptions discOpts = DisconOptsInit(onDisconnect, NULL, client);
//成功返回 DMSASYNC_SUCCESS，否则返回错误代码
DMSAsync_disconnect(client, &discOpts);
//等待断开成功...
while (isDisconnected==0) Sleep(100);
...
void onDisconnect(void* context, DMSAsync_successData* response)
{
    printf("onDisconnect\n");
    isDisconnected = 1;
}

释放对象

DMSAsync_destroy(&client);

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