Package com.framed.core.remote

Class NioTcpTransport

java.lang.Object
com.framed.core.remote.NioTcpTransport
All Implemented Interfaces:
Transport
public class NioTcpTransport extends Object implements Transport
A Transport implementation using Java NIO for TCP-based communication.

This class provides non-blocking I/O for message exchange between components, services or devices using a simple JSON-based protocol. Messages are framed by newline characters and contain fields for address, payload, and type.

Features:

Message Format:


 {
   "address": "topic.name",
   "payload": "data",
   "type": "send" | "publish"
 }

Example usage:


 NioTcpTransport transport = new NioTcpTransport(8080);
 transport.register("sensor.data", msg -> System.out.println("Received: " + msg));
 transport.start();

 transport.send("localhost", 8080, "sensor.data", "Hello");

Connection model

One TCP connection is kept open per target host:port and reused for every message sent to that peer. Messages are newline-delimited on that stream, so a single connection carries an unbounded sequence of them.

This matters for throughput. An earlier implementation opened a fresh SocketChannel per message — connect, write, close — making one datapoint one TCP connection; the receiving instance accepts on a single selector thread and could not drain the listen backlog, so above roughly 7,400 messages/s the kernel dropped SYNs and 10–30 % of messages were lost while write still returned successfully and no failure was reported. Reuse removes the per-message handshake entirely and turns silent loss into backpressure: writes are blocking, so a sender outrunning its peer is throttled by the socket rather than having data discarded.

Threading

Writes to one peer are serialized on that peer's connection — concurrent senders would otherwise interleave partial JSON on the stream and corrupt the newline framing. Writes to different peers proceed in parallel. A write blocks its calling thread while the peer's receive window is full, which is the intended backpressure; callers must therefore not write from an event-bus handler thread (SocketEventBus already publishes to peers on its own pool). Reading happens on the single selector thread; handler invocation is handed to the worker pool.

Note: Always call shutdown() to release resources when done.

  • Constructor Summary

    Constructors
    Constructor
    Description
    NioTcpTransport(int port)
    Creates a new NIO TCP transport bound to the specified port.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    publish(String host, int port, String address, Object message)
    Publishes a message to all subscribers of the specified address.
    void
    register(String address, Consumer<Object> handler)
    Registers a handler for messages received on the specified address.
    void
    send(String host, int port, String address, Object message)
    Sends a message to the first subscriber of the specified address.
    void
    shutdown()
    Shuts down the transport, closing the selector, server channel, and worker pool.
    void
    start()
    Starts the transport event loop in a background thread.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • NioTcpTransport

      public NioTcpTransport(int port) throws IOException
      Creates a new NIO TCP transport bound to the specified port.
      Parameters:
      port - the TCP port to listen on
      Throws:
      IOException - if the server socket or selector cannot be initialized

  • Method Details

    • start

      public void start()
      Starts the transport event loop in a background thread.

      Accepts new connections and reads incoming messages asynchronously.

      Specified by:
      start in interface Transport

    • send

      public void send(String host, int port, String address, Object message)
      Sends a message to the first subscriber of the specified address.
      Specified by:
      send in interface Transport
      Parameters:
      host - the target host
      port - the target port
      address - the logical address for the message
      message - the message payload

    • publish

      public void publish(String host, int port, String address, Object message)
      Publishes a message to all subscribers of the specified address.
      Specified by:
      publish in interface Transport
      Parameters:
      host - the target host
      port - the target port
      address - the logical address for the message
      message - the message payload

    • shutdown

      public void shutdown()
      Shuts down the transport, closing the selector, server channel, and worker pool.
      Specified by:
      shutdown in interface Transport

    • register

      public void register(String address, Consumer<Object> handler)
      Registers a handler for messages received on the specified address.
      Specified by:
      register in interface Transport
      Parameters:
      address - the address to listen on
      handler - the handler to process messages