MQTT 5

This binding type is marked obsolete in the source API and is retained for compatibility. It registers only a server binding under mqtt5; MQTT's current server/operation/message bindings are documented separately.

Write

SessionExpiryInterval is MQTTIntegerOrSchema. A long and an AsyncApiJsonSchema convert implicitly to the union. AsyncApiJsonSchemaReference needs no separate operator: it derives from AsyncApiJsonSchema and uses the schema conversion. Select the value form you need, then attach the binding to a server:

using ByteBard.AsyncAPI.Bindings.MQTT;
using ByteBard.AsyncAPI.Bindings.MQTT5;
using ByteBard.AsyncAPI.Models;

var scalarBinding = new MQTT5ServerBinding
{
    SessionExpiryInterval = 500,
};
var schemaBinding = new MQTT5ServerBinding
{
    SessionExpiryInterval = new AsyncApiJsonSchema { Type = SchemaType.Integer },
};
var referenceBinding = new MQTT5ServerBinding
{
    SessionExpiryInterval = new AsyncApiJsonSchemaReference("#/components/schemas/interval"),
};

var scalarServer = new AsyncApiServer();
scalarServer.Bindings.Add(scalarBinding);
var schemaServer = new AsyncApiServer();
schemaServer.Bindings.Add(schemaBinding);
var server = new AsyncApiServer();
server.Bindings.Add(referenceBinding);

Bindings.Add(binding) stores each instance under its BindingKey (mqtt5).

The integer, inline-schema, and reference alternatives are written directly, without a union wrapper object.

Read and use

Register BindingsCollection.MQTT5 to read this legacy binding. The scalar input produces MQTTInteger; the $ref input produces MQTTIntegerSchema whose Schema can be tested for AsyncApiJsonSchemaReference.

using System;
using ByteBard.AsyncAPI;
using ByteBard.AsyncAPI.Bindings;
using ByteBard.AsyncAPI.Bindings.MQTT;
using ByteBard.AsyncAPI.Bindings.MQTT5;
using ByteBard.AsyncAPI.Models;
using ByteBard.AsyncAPI.Readers;

var settings = new AsyncApiReaderSettings { Bindings = BindingsCollection.MQTT5 };
var reader = new AsyncApiStringReader(settings);
var scalarServer = reader.ReadFragment<AsyncApiServer>("""
    host: broker.example
    protocol: mqtt
    bindings:
      mqtt5:
        sessionExpiryInterval: 500
    """, AsyncApiVersion.AsyncApi3_0, out var diagnostics);
if (scalarServer.Bindings.TryGetValue<MQTT5ServerBinding>(out var scalar) &&
    scalar.SessionExpiryInterval is MQTTInteger integer)
{
    Console.WriteLine(integer.Value);
}

var referenceServer = reader.ReadFragment<AsyncApiServer>("""
    host: broker.example
    protocol: mqtt
    bindings:
      mqtt5:
        sessionExpiryInterval:
          $ref: '#/components/schemas/interval'
    """, AsyncApiVersion.AsyncApi3_0, out _);
if (referenceServer.Bindings.TryGetValue<MQTT5ServerBinding>(out var referenced) &&
    referenced.SessionExpiryInterval is MQTTIntegerSchema { Schema: AsyncApiJsonSchemaReference schemaReference })
{
    Console.WriteLine(schemaReference.Reference.Reference);
}

TryGetValue<TBinding> returns false if no binding with that type's BindingKey is present; the union pattern then distinguishes the scalar and schema values.

The union is also used by MQTT's server and operation fields. MQTT 5's binding is deprecated, and BindingsCollection.MQTT5 has no channel, operation, or message parser. AsyncAPI 2.x and 3.x serialization are supported; specify a target version when serializing. See the shared guide.