TCP Client

A MasterChannel presents the same interface once you create it, regardless of the underlying transport. You can create a TCP client channel using the runtime, configuration data, and a callback to observe the status of the connection.

Rust

let channel = spawn_master_tcp_client(
    LinkErrorMode::Close,
    get_master_channel_config()?,
    EndpointList::new("127.0.0.1:20000".to_owned(), &[]),
    ConnectStrategy::default(),
    NullListener::create(),
);

note

The function is called within the context of the Tokio runtime, and is therefore implicit in Rust.

C

dnp3_master_channel_t* channel = NULL;
dnp3_endpoint_list_t* endpoints = dnp3_endpoint_list_create("127.0.0.1:20000");
dnp3_param_error_t err = dnp3_master_channel_create_tcp(
    runtime,
    DNP3_LINK_ERROR_MODE_CLOSE,
    get_master_channel_config(),
    endpoints,
    dnp3_connect_strategy_init(),
    get_client_state_listener(),
    &channel
);
dnp3_endpoint_list_destroy(endpoints);
// check error

C++

dnp3::EndpointList endpoints(std::string("127.0.0.1:20000"));

auto channel = dnp3::MasterChannel::create_tcp_channel(
    runtime,
    dnp3::LinkErrorMode::close,
    get_master_channel_config(), endpoints,
    dnp3::ConnectStrategy(),
    std::make_unique<ClientStateListener>()
);

Java

MasterChannel channel =
        MasterChannel.createTcpChannel(
                runtime,
                LinkErrorMode.CLOSE,
                getMasterChannelConfig(),
                new EndpointList("127.0.0.1:20000"),
                new ConnectStrategy(),
                new TestClientStateListener());

C#

var channel = MasterChannel.CreateTcpChannel(
    runtime,
    LinkErrorMode.Close,
    GetMasterChannelConfig(),
    new EndpointList("127.0.0.1:20000"),
    new ConnectStrategy(),
    new TestClientStateListener()
);

Enabling

A MasterChannel won't start communicating until you call the enable method. This gives you the opportunity to configure all the associations on the channel, as discussed in the next section. You can also disable the channel to put it in an inactive state.

LinkErrorMode

The LinkErrorMode controls what happens if it detects a framing error at the link-layer. TCP is a lossless transport, so the default behavior is to close the connection. However, you can treat a TCP channel like a serial port by changing the setting to LinkErrorMode::Discard.

EndpointList

An EndpointList is a list of remote endpoints that the master will try to connect to. It must contain at least one entry, with the option to include additional backup addresses. The channel will round-robin through this list until it establishes a connection. The list may contain endpoints consisting of a <host>:<port> tuple where "host" is one of the following:

• IPv4 address
• IPv6 address
• Domain name

ConnectStrategy

The ConnectStrategy controls the rate at which the master retries failed connection attempts. The master uses exponential backoff when attempting to establish a connection. The delay between attempts doubles from minConnectDelay up to maxConnectDelay. If a connection fails after previously connecting, it will wait reconnectDelay before the next attempt.

ClientStateListener

The ClientStateListener interface has a single callback to inform the application about the state of connection.