IoT_Callbacks

The eXtremeDB Active Replication Fabric callbacks are functions defined with the structures described below.

For an overview see page ARF Applications in C

The following structures are used to define callback functions which are registered with mco_iot_comm_register_callback() and dropped with mco_iot_comm_unregister_callback():

 
    typedef struct mco_iot_read_stream_t_
    {
        void            *handle;
        mco_stream_read  reader;
    } mco_iot_read_stream_t;
     
    typedef struct iot_ack_t_ 
    {
        uint8     seq;
        uint8     sender_agent_id;
        uint8     receiver_agent_id;
        uint8     timestamp;
        uint4     error_code;
    } iot_ack_t;
     
    typedef struct iot_comm_callback_t_
    {
        int (*onConnect)    (mco_iot_connection_h iotc, void *context);
        int (*onReceive)    (mco_iot_connection_h iotc, mco_iot_read_stream_t *stream, void *context);
        int (*onAck)        (mco_iot_connection_h iotc, const iot_ack_t *ack, void *context);
        int (*onDisconnect) (mco_iot_connection_h iotc, void *context);
        int (*onDestroy)    (mco_iot_connection_h iotc, void *context);
    } iot_comm_callback_t;
 

Callback Events

The callback functions defined in structure iot_comm_callback_t are called for the following events:

onConnect	Called when the a communication is established either through connect() or accept()
onReceive	Called when data is received (a set of serialized objects)
onAck	Called when the acknowledgment for previously sent data (ACK message) is received
onDisconnect	Called when a connection is disconnected
onDestroy	Called prior to destroying a connection

Usage

Note that the void * context argument is a user-defined context (a pointer to a structure containing application-specific data). Any of the callback functions registered in the iot_comm_callback_t_ structure must either return IOT_CALLBACK_OK (successful completion) or IOT_CALLBACK_FAIL (in case of an error, the corresponding connection will be disconnected). Also note that if the callback is not used, it can be set to null.

Example

     
    {
        ...
        iot_comm_callback_t my_callback = {&my_on_connect, 0, 0, &my_on_disconnect, 0};
        ...
        mco_iot_comm_register_callback(comm, &my_callback, my_context);
    }