A callback type can be any one of the following:
    CALLBACK_START
    CALLBACK_WAIT
    CALLBACK_FINISH
    CALLBACK_MESSAGE
    CALLBACK_CONN_DROPPED
    CALLBACK_DEBUG_MESSAGE
    CALLBACK_VALIDATE_FILE_TRANSFER


The following example shows a simple message callback routine and how to register it.
void SQLANY_CALLBACK messages(
    a_sqlany_connection *sqlany_conn,
    a_sqlany_message_type msg_type,
    int sqlcode,
    unsigned short length,
    char *msg )
{
    size_t  mlen;
    char    mbuffer[80];

    mlen = __min( length, sizeof(mbuffer) );
    strncpy( mbuffer, msg, mlen );
    mbuffer[mlen] = '\0';
    printf( "Message is \"s".
", mbuffer );
    sqlany_sqlstate( sqlany_conn, mbuffer, sizeof( mbuffer ) );
    printf( "SQLCode(%d) SQLState(\"s")

", sqlcode, mbuffer );
}