Subscribing to a Stream in Callback Mode

Subscribing in callback mode is a multistep process that involves creating a subscriber and callback registry, connecting to the subscriber, and then subscribing to a stream.

The following code snippets are provided to illustrate one way of subscribing and not as a complete, working example. Adapt this sample as necessary to suit your particular subscription scenario.

Create a subscriber:

NetEspSubscriberOptions options = new NetEspSubscriberOptions();
options.set_mode(NetEspSubscriberOptions.NET_ESP_ACCESS_MODE_T.NET_CALLBACK_ACCESS);
NetEspSubscriber subscriber = project.create_subscriber(options,error);

Create the callback registry:

NetEspSubscriber.SUBSCRIBER_EVENT_CALLBACK callbackInstance = new NetEspSubscriber.SUBSCRIBER_EVENT_CALLBACK(subscriber_callback);
subscriber.set_callback(NetEspSubscriber.NET_ESP_SUBSCRIBER_EVENT.NET_ESP_SUBSCRIBER_EVENT_ALL, callbackInstance, null, error);

Connect to the subscriber:
```
subscriber.connect(error);
```

Subscribe to a stream:

subscriber.subscribe_stream(stream, error);

Callback function implementation:

Public static void subscriber_callback(NetEspSubscriberEvent event, ValueType
data) {
        switch (evt.getType())
            {
               case (uint)(NetEspSubscriber.NET_ESP_SUBSCRIBER_EVENT.NET_ESP_SUBSCRIBER_EVENT_CONNECTED):
                    Console.WriteLine("the callback happened: connected!");
                    break;
(uint)( NetEspSubscriber.NET_ESP_SUBSCRIBER_EVENT.NET_ESP_SUBSCRIBER_EVENT_DATA):
        //handleData
        ...
			break;
        
                default:
                    break;
            }
}//end subscriber_callback

handleData implementation:

NetEspRowReader row_reader = null;
while ((row_reader = evt.getMessageReader().next_row(error)) != null) {
                for (int i = 0; i < schema.get_numcolumns(); ++i) {
                    if ( row_reader.is_null(i) == 1) {
                        Console.Write("null, ");
                        continue;
                    }
                    switch (NetEspStream.getType(schema.get_column_type((uint)i, error)))
                    {
                        case NetEspStream.NET_DATA_TYPE_T.NET_ESP_DATATYPE_INTEGER:
                            ivalue = row_reader.get_integer(i, error);
                            Console.Write(ivalue + ", ");
                            break;
                        case NetEspStream.NET_DATA_TYPE_T.NET_ESP_DATATYPE_LONG:
                            lvalue = row_reader.get_long(i, error);
                            Console.Write(lvalue + ", ");
                            break;
                        case NetEspStream.NET_DATA_TYPE_T.NET_ESP_DATATYPE_FLOAT:
                            fvalue = row_reader.get_float(i, error);
                            Console.Write(fvalue + ", ");
                            break;
                        case NetEspStream.NET_DATA_TYPE_T.NET_ESP_DATATYPE_STRING:
                            svalue = row_reader.get_string(i, error);
                            Console.Write(svalue);
                            break;
                        case NetEspStream.NET_DATA_TYPE_T.NET_ESP_DATATYPE_DATE:
                            dvalue = row_reader.get_date(i, error);
                            Console.Write(dvalue + ", ");
                            break;
                        case NetEspStream.NET_DATA_TYPE_T.NET_ESP_DATATYPE_TIMESTAMP:
                            tvalue = row_reader.get_timestamp(i, error);
                            Console.Write(tvalue + ", ");
                            break;
                        case NetEspStream.NET_DATA_TYPE_T.NET_ESP_DATATYPE_BOOLEAN:
                            boolvalue = row_reader.get_boolean(i, error);
                            Console.Write(boolvalue + ", ");
                            break;
                        case NetEspStream.NET_DATA_TYPE_T.NET_ESP_DATATYPE_BINARY:
                            uint buffersize = 256;
                            binvalue = row_reader.get_binary(i, buffersize, error);
                            Console.Write(System.Text.Encoding.Default.GetString(binvalue) + ", ");
                            break;
                        case NetEspStream.NET_DATA_TYPE_T.NET_ESP_DATATYPE_INTERVAL:
                            intervalue = row_reader.get_interval(i, error);
                            Console.Write(intervalue + ", ");
                            break;
                        case NetEspStream.NET_DATA_TYPE_T.NET_ESP_DATATYPE_MONEY01:
                            mon = row_reader.get_money(i, error);
                            Console.Write(mon.get_long(error) + ", ");
                            break;
                        case NetEspStream.NET_DATA_TYPE_T.NET_ESP_DATATYPE_MONEY02:
                            lvalue = row_reader.get_money_as_long(i, error);
                            Console.Write(lvalue + ", ");
                            break;
                        case NetEspStream.NET_DATA_TYPE_T.NET_ESP_DATATYPE_MONEY03:
                            mon = row_reader.get_money(i, error);
                            Console.Write(mon.get_long(error) + ", ");
                            break;
                        case NetEspStream.NET_DATA_TYPE_T.NET_ESP_DATATYPE_MONEY10:
                            mon = row_reader.get_money(i, error);
                            Console.Write(mon.get_long(error) + ", ");
                            break;
                        case NetEspStream.NET_DATA_TYPE_T.NET_ESP_DATATYPE_MONEY15:
                            mon = row_reader.get_money(i, error);
                            Console.Write(mon.get_long(error) + ", ");
                            break;
                        case NetEspStream.NET_DATA_TYPE_T.NET_ESP_DATATYPE_BIGDATETIME:
                            bdt2 = row_reader.get_bigdatetime(i, error);
                            long usecs = bdt2.get_microseconds(error);
                            Console.Write(usecs + ", ");
                            break;
                    }
            }

            rc = subscriber.disconnect(error); 
}