server-event-example.c

Respond to events such as Client Register, Client Deregister and Client Update.

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/*
 * This example demonstrates how to respond to client events from the server.
 *
 * If a client registers, deregisters or updates its registration with the server,
 * an application callback is invoked.
 *
 * To run this example, run an Awa server and then run this example. Then
 * start a LWM2M client (such as the Awa client) and have it register with this
 * server. Hit CTRL-C to terminate.
 */

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <signal.h>

#include <awa/common.h>
#include <awa/server.h>

#define IPC_PORT (54321)
#define IPC_ADDRESS "127.0.0.2"
#define OPERATION_PERFORM_TIMEOUT 1000

/*
 * This function will be called by the API when a client registers
 * with the server and generates a ClientRegister event.
 * When invoked, event provides information about the client concerned.
 */
static void clientRegisterCallback(const AwaServerClientRegisterEvent * event, void * context)
{
    int * eventCount = (int *)context;
    (*eventCount)++;

    /* Display client ID and registered entities */
    AwaClientIterator * clientIterator = AwaServerClientRegisterEvent_NewClientIterator(event);

    while (AwaClientIterator_Next(clientIterator))
    {
        const char * clientID =  AwaClientIterator_GetClientID(clientIterator);
        printf("Event %d: Client %s registered:\n  ", *eventCount, clientID);
        AwaRegisteredEntityIterator * entityIterator = AwaServerClientRegisterEvent_NewRegisteredEntityIterator(event, clientID);
        while (AwaRegisteredEntityIterator_Next(entityIterator))
        {
            printf(" %s", AwaRegisteredEntityIterator_GetPath(entityIterator));
        }
        printf("\n");
        AwaRegisteredEntityIterator_Free(&entityIterator);
    }
    AwaClientIterator_Free(&clientIterator);
}

/*
 * This function will be called by the API when a client deregisters
 * with the server and generates a ClientDeregister event.
 * When invoked, event provides information about the client concerned.
 */
static void clientDeregisterCallback(const AwaServerClientDeregisterEvent * event, void * context)
{
    int * eventCount = (int *)context;
    (*eventCount)++;

    /* Display client ID */
    AwaClientIterator * clientIterator = AwaServerClientDeregisterEvent_NewClientIterator(event);

    while (AwaClientIterator_Next(clientIterator))
    {
        const char * clientID =  AwaClientIterator_GetClientID(clientIterator);
        printf("Event %d: Client %s deregistered.\n", *eventCount, clientID);
    }
    AwaClientIterator_Free(&clientIterator);
}

/*
 * This function will be called by the API when a client updates its
 * registration with the server and generates a ClientUpdate event.
 * When invoked, event provides information about the client concerned.
 */
static void clientUpdateCallback(const AwaServerClientUpdateEvent * event, void * context)
{
    int * eventCount = (int *)context;
    (*eventCount)++;

    /* Display client ID and registered entities */
    AwaClientIterator * clientIterator = AwaServerClientUpdateEvent_NewClientIterator(event);

    while (AwaClientIterator_Next(clientIterator))
    {
        const char * clientID =  AwaClientIterator_GetClientID(clientIterator);
        printf("Event %d: Client %s updated:\n  ", *eventCount, clientID);
        AwaRegisteredEntityIterator * entityIterator = AwaServerClientUpdateEvent_NewRegisteredEntityIterator(event, clientID);
        while (AwaRegisteredEntityIterator_Next(entityIterator))
        {
            printf(" %s", AwaRegisteredEntityIterator_GetPath(entityIterator));
        }
        printf("\n");
        AwaRegisteredEntityIterator_Free(&entityIterator);
    }
    AwaClientIterator_Free(&clientIterator);
}

static bool stopFlag = false;

/*
 * Trigger the program to exit on CTRL-C
 */
static void stop(int ignore)
{
    printf("Exiting...\n");
    stopFlag = true;
}

int main(void)
{
    signal(SIGINT, stop);

    /* Create and initialise server session */
    AwaServerSession * session = AwaServerSession_New();

    /* Use default IPC configuration */
    AwaServerSession_Connect(session);

    int eventCount = 0;

    /* Provide a callback function to the API for Client Register events */
    AwaServerSession_SetClientRegisterEventCallback(session, clientRegisterCallback, &eventCount);

    /* Provide a callback function to the API for Client Deregister events */
    AwaServerSession_SetClientDeregisterEventCallback(session, clientDeregisterCallback, &eventCount);

    /* Provide a callback function to the API for Client Update events */
    AwaServerSession_SetClientUpdateEventCallback(session, clientUpdateCallback, &eventCount);

    /* Wait for events */
    while (!stopFlag)
    {
        /* Receive events */
        AwaServerSession_Process(session, OPERATION_PERFORM_TIMEOUT);
        AwaServerSession_DispatchCallbacks(session);
    }

    AwaServerSession_Disconnect(session);
    AwaServerSession_Free(&session);
    return 0;
}