Deliver messages from sender to recipient

By combining receive message and send message examples we can implement basic way to deliver messages from sender to recipient via SMPP-server. Let’s make a method for receiving inbound messages from an SMPP-client, searching suitable recipient among SMPP-clients connected and sending the message to it. For the sake of example, let us consider any SMPP-client having SystemID (login) equal to message "To" field as "suitable".

private static async Task Main(string[] args)
{
    LogManager.SetLoggerFactory(new ConsoleLogFactory(LogLevel.Verbose));

    SmppServer _server = new SmppServer(new IPEndPoint(IPAddress.Any, 7777));

    _server.evClientBind += (s, c, p) => { }; //allow all to authenticate on the server
    _server.evClientSubmitSm += async (smppServer, smppServerClient, submitSm) => await ForwardSms(smppServer, smppServerClient, submitSm);

    await _server.StartAsync();

    Console.ReadLine();
}

private static async Task ForwardSms(object smppServer, SmppServerClient smppServerClient, SubmitSm submitSm)
{
    SmppServer _server = (SmppServer)smppServer;

    //prepare message
    string fromField = submitSm.SourceAddress.ToString();
    string toField = submitSm.DestinationAddress.ToString();
    string textField = submitSm.GetMessageText(smppServerClient.EncodingMapper);

    //search recepient
    SmppServerClient clientRecepient = _server.ConnectedClients.FirstOrDefault(c => c.SystemID == toField);

    //send
    if (clientRecepient != null)
    {
        IList<DeliverSm> textMessage = SMS.ForDeliver().From(fromField).To(toField).Text(textField).Create(clientRecepient);
        var result = await clientRecepient.DeliverAsync(textMessage);
    }
}

There is an event handler created and named “ForwardSms”. It is subscribed to evClientSubmitSm event, responsible for inbound messages. The event handler is getting the inbound message as a third argument (submitSm) and prepares it for sending further. In addition, it picks the suitable recipient out of the list of SMPP-clients connected (ConnectedClients property) and forwards message to it.

To test the setup, connect two SMPP-clients (sender and recipient) to this SMPP-server. Sender login is not important, but for recipient login use “client002”. Now send a message from the first SMPP-client and put “client002” in the “Destination (To)” field. The message should arrive to client with login “client002”. It will work even if you have only one SMPP-client connected but "To" field contains its login. Of course, the way of choosing the recipient is totally up to the developer.

Using a similar approach it is possible to implement the SMPP Gateway for forwarding messages via SMPP-client connected to another SMPP-server.

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Deliver messages from sender to recipient