Sgcwebsockets Dotnet Mq

sgcWebSockets .NET Message Brokers

Eight components that speak the wire protocols of the common message brokers. None of them owns a socket. Each attaches to a transport client through its Client property, and the transport is what connects, reconnects and does TLS. Get that relationship right and the rest follows.

Read sgcwebsockets-dotnet first for the transport client and the threading rule, both of which apply here unchanged.

When to use this skill

• Publish to or subscribe from an MQTT broker (Mosquitto, HiveMQ, EMQX)
• Talk STOMP to RabbitMQ or ActiveMQ
• Talk AMQP 0.9.1 to RabbitMQ, or AMQP 1.0 to a broker that speaks it
• Produce to or consume from Kafka
• Call and subscribe over WAMP2

Components in this skill

Before you start, ask the developer

Use a structured question tool if your host has one, for example Claude Code's AskUserQuestion. Otherwise ask in chat:

1. Which broker, and which port? A broker on 1883 or 5672 is plain TCP, not WebSocket, and that changes one setting on the transport. See below.
2. MQTT 3.1.1 or 5? MQTTVersion picks it. Version 5 adds the properties and reason codes; a version 5 feature against a 3.1.1 broker is refused.
3. What QoS? 0, 1 and 2 are three different delivery contracts and three different amounts of work. Ask rather than defaulting.
4. Does the application need to know it lost messages? That decides whether you need a last will, a clean session, or both.

Quickstart, MQTT

using esegece.sgcWebSockets;

var client = new TsgcWebSocketClient();
client.Host = "test.mosquitto.org";
client.Port = 8080;

var mqtt = new TsgcWSPClient_MQTT();
mqtt.Client = client;                       // the socket lives on the client
mqtt.MQTTVersion = TwsMQTTVersion.mqtt311;

mqtt.OnMQTTConnect += (TsgcWSConnection connection, bool session,
    int reasonCode, string reasonName,
    TsgcWSMQTTCONNACKProperties properties) =>
        mqtt.Subscribe("sgcWebSockets/test");

mqtt.OnMQTTPublish += (TsgcWSConnection connection, string topic, string text,
    TsgcWSMQTTPublishProperties properties) =>
        Console.WriteLine(topic + ": " + text);

client.Active = true;                        // connects the socket

Subscribe, UnSubscribe and Publish(topic, text) are the everyday methods. PublishAndWait(topic, text, qos, timeout) returns a bool and is the one to reach for when the application has to know the broker took it.

Check the delegate signatures on the type pages before writing a handler. The MQTT events carry several parameters and the order is not guessable.

Plain TCP brokers, the setting people miss

A broker on port 1883, 5672 or 61613 speaks its protocol over raw TCP, not over WebSocket. On the transport client set:

client.Specifications.RFC6455 = false;

Without it the client sends a WebSocket handshake, the broker does not answer one, and the connection dies with something that reads like a network fault. A broker reached on 8080 or 443 usually is over WebSocket and wants the default.

Things that catch people out

• Setting Active = true on the protocol component does nothing useful. The transport client owns the connection; start that.
• One transport carries one protocol. Two protocol components pointed at the same client is the usual cause of a broker rejecting the handshake.
• Client is typed TsgcTCPComponent_Client, so a plain TsgcTCPClient works as the transport for a TCP broker. That is a feature, not an accident.
• MQTT has two heartbeats: HeartBeat on the MQTT component is the protocol keepalive, and HeartBeat on the transport client is the WebSocket ping. They are different mechanisms with the same name.
• Reconnect belongs to the transport. Set client.WatchDog, not anything on the protocol component.
• QoS 2 is a four-message exchange. Tracking delivery yourself means handling OnMQTTPubRec, OnMQTTPubRel and OnMQTTPubComp, not just OnMQTTPubAck.
• Disconnect on the MQTT component takes a reason code, an int. It is the MQTT 5 disconnect reason, and it is not a timeout.

Routing

• API detail: reference/api/<Component>.md has the properties, events and methods, each with its C# signature.
• Option / enum / delegate types: property and event types link to reference/types/<TypeName>.md.
• Examples: examples/<Component>.md is a trimmed snippet from the shipped demo; examples/index.md maps every component to its demo.
• Getting started: concepts/overview.md covers the single using, the target frameworks and the naming.

What is documented

Public instance properties, events and methods declared anywhere in the library's own class chain. Members inherited from the .NET base classes are left out, as are internals, so a page shows the surface a caller writes against and nothing else.

If a component you need is not here, read concepts/coverage.md in the sgcwebsockets-dotnet skill before assuming a different name for it. This assembly carries fewer components than the Delphi library, and saying so is more useful than guessing an API that does not exist.