OpcLabs.MqttNet communication package

This communication package is based on MQTTnet and MQTTnet.Extensions.ManagedClient libraries by Christian Kratky. See MQTT communication packages for a summary of the communication package and the library. The library supports Client and Server roles; the communication package only supports the Client role.

See Using communication packages for instructions on how to select the communication package, and configure it.

Client role

The type name of the message channel object is: OpcLabs.MqttNet.ManagedMqttClientMessageChannel,OpcLabs.MqttNet .

Opening the channel

URL string

If the URL string has "mqtt", "mqtts", "ssl", "tcp" or "tls" scheme, TCP protocol (possibly with SSL/TLS) will be used. In this case, the URL is parsed by the communication package and various pieces of information are extracted from it. The syntax is:

scheme:[//[username[:password]@]host[:port]][/clientId=clientId]

If the client credentials have not been specified in the configuration (see below), which is the default, the username and password from the URL are used. The port defaults to 1883 for "mqtt", "tcp" schemes, and to 8883 for "mqtts", "ssl" schemes.

The "mqtt" and "tcp" schemes are equivalent, and denote a use of TCP protocol without SSL/TLS. The "mqtts", "ssl" and "tls" schemes are equivalent, and denote a use of TCP protocol with SSL/TLS.

Using the clientId query parameter you can override the default clientId supplied by host software. Additional query parameters can be specified, and are ignored.

Examples:

mqtt://test.mosquitto.org
mqtts://test.mosquitto.org

If the URL string has "ws" or "wss" scheme, WebSocket protocol (possibly with TLS, for "wss") will be used. In this case, the URL is passed onto the underlying library unchanged (the user info is still extracted from it and interpreted by the communication package).

Examples:

ws://test.mosquitto.org:8080/mqtt
wss://test.mosquitto.org:8081/mqtt

If the scheme in the URL is not one of the schemes listed here, the message channel will still open, using the clientId and cleanSession flag provided by the host software, and all other parameters given by the configuration properties. This will fail under normal circumstances - unless you have carefully set all properties as necessary.

Interface name

The interface name, if provided by the host software, is ignored.

Certificates

Due to limitations imposed by the underlying library, if the host software specifies its own server certificate validation, this validation can allow additional server certificates be accepted over what the library accepts by default, but no server certificate accepted by the library by its default mechanism can be rejected by the host validation. Also, the host can provide a list of client certificates, but cannot influence the certificate selection.

Configuration

The table below lists the available properties, their types, and descriptions. Most properties come from configurable options of the underlying library, so please refer to the its documentation for details (we could not find a comprehensive reference documentation for this library, that's why most descriptions are missing). Do not get scared by the number of configurable properties; the relevant ones can usually stay at their defaults, or usually overridden from the host software (as noted). We will emphasize specific properties if they are important.

Property	Type	Description
ClientWaitTimeout	System.Int32	Determines the maximum wait time for the client to open before publishing a message. In milliseconds.
ManagedMqttClientOptions	MQTTnet.Extensions.ManagedClient.ManagedMqttClientOptions
ManagedMqttClientOptions.AutoReconnectDelay	System.TimeSpan	Default is 5 seconds.
ManagedMqttClientOptions.ClientOptions	MQTTnet.Client.Options.IMqttClientOptions
ManagedMqttClientOptions.ConnectionCheckInterval	System.TimeSpan	Default is 1 second.
ManagedMqttClientOptions.MaxPendingMessages	System.Int32	Default is 2^31-1.
ManagedMqttClientOptions. PendingMessagesOverflowStrategy	MQTTnet.Server.MqttPendingMessagesOverflowStrategy	Default is DropNewMessage.
ManagedMqttClientOptions.Storage	MQTTnet.Extensions.ManagedClient.IManagedMqttClientStorage
MqttClientOptions	MQTTnet.Client.Options.MqttClientOptions
MqttClientOptions.AuthenticationData	System.Byte[]
MqttClientOptions.AuthenticationMethod	System.String
MqttClientOptions.ChannelOptions	MQTTnet.Client.Options.IMqttClientChannelOptions	Default value is null. For known URL schemes, it gets overridden by a value determined during URL resolution. For "mqtt", "mqtts", "ssl", "tcp" and "tls" schemes, value from the MqttClientTcpOptions property is used. For "ws", "wss" schemes, value from the MqttClientWebSocketOptions is used.
MqttClientOptions.CleanSession	System.Boolean	Always override by the value specified by the host software (do not use).
MqttClientOptions.ClientId	System.String	Default value is null. When null, gets overridden by the ClientId specified by the host software. For "mqtt", "mqtts", "ssl", "tcp" and "tls" URL schemes, it can further be overridden by a "clientId" query parameter in the URL.
MqttClientOptions.Credentials	MQTTnet.Client.Options.IMqttClientCredentials	Default value is null. When null, for "mqtt", "mqtts", "ssl", "tcp" and "tls" URL schemes, if the URL contains user-specific information, gets overridden by the credentials with user name and password from the URL.
MqttClientOptions.CommunicationTimeout	System.Timespan	Default is 10 seconds.
MqttClientOptions. ExtendedAuthenticationExchangeHandler	MQTTnet.Client.ExtendedAuthenticationExchange.IMqttExtendedAuthenticationExchangeHandler
MqttClientOptions.KeepAlivePeriod	System.Timespan	Default is 15 seconds.
MqttClientOptions.KeepAliveSendInterval	System.Nullable<System.TimeSpan>
MqttClientOptions.MaximumPacketSize	System.Nullable<System.UInt32>
MqttClientOptions.ProtocolVersion	MQTTnet.Formatter.MqttProtocolVersion	Default is V311. Other values: Unknown, V310, V500.
MqttClientOptions.ReceiveMaximum	System.Nullable<UInt16>
MqttClientOptions.RequestProblemInformation	System.Nullable<System.Boolean>
MqttClientOptions.RequestResponseInformation	System.Nullable<System.Boolean>
MqttClientOptions.SessionExpiryInterval	System.Nullable<System.UInt32>
MqttClientOptions.TopicAliasMaximum	System.Nullable<System.UInt16>
MqttClientOptions.WillDelayInterval	System.Nullable<System.UInt16>
MqttClientTcpOptions	MQTTnet.Client.Options.MqttClientTcpOptions
MqttClientTcpOptions.AddressFamily	System.Net.Sockets.AddressFamily	Default is Unspecified.
MqttClientTcpOptions.BufferSize	System.Int32	Default is 65536.
MqttClientTcpOptions.DualMode	System.Nullable<System.Boolean>
MqttClientTcpOptions.NoDelay	System.Boolean
MqttClientTcpOptions.Port	System.Nullable<System.Int32>	For "mqtt", "tcp" URL schemes, gets overridden by the value specified in the URL, or 1883 if not specified. For "mqtts", "ssl" and "tls" URL schemes, gets overridden by the value specified in the URL, or 8883 if not specified.
MqttClientTcpOptions.Server	System.String
MqttClientTcpOptions.TlsOptions	MQTTnet.Client.Options.MqttClientTlsOptions	For "mqtt", "tcp", "mqtts", "ssl" and "tls" URL schemes, some sub-properties (described here) get overridden.
MqttClientTcpOptions.TlsOptions. AllowUntrustedCertificates	System.Boolean
MqttClientTcpOptions.TlsOptions.Certificates	System.List<System.Security.Cryptography.X509Certificates.X509Certificate> (.NET Framework) System.List<System.Byte[]> (.NET Standard)	For "mqtts", "ssl" and "tls" URL schemes, may get overridden by hosting software.
MqttClientTcpOptions.TlsOptions. CertificateValidationCallback	System.Func<System.Security.Cryptography.X509Certificates.X509Certificate, System.Security.Cryptography.X509Certificates.X509Chain, System.Net.Security.SslPolicyErrors, MQTTnet.Client.Options.IMqttClientOptions, System.Boolean>	For "mqtts", "ssl" and "tls" URL schemes, may get overridden by hosting software.
MqttClientTcpOptions.TlsOptions. IgnoreCertificateChainErrors	System.Boolean
MqttClientTcpOptions.TlsOptions. IgnoreCertificateRevocationErrors	System.Boolean
MqttClientTcpOptions.TlsOptions.SslProtocol	System.Security.Authentication.SslProtocols	Default is Tls12.
MqttClientTcpOptions.TlsOptions.UseTls	System.Boolean	Gets overriden to false for "mqtt", "tcp" URL schemes, gets overridden to true for "mqtts", "ssl" and "tls" URL schemes.
MqttClientWebSocketOptions	MQTTnet.Client.Options.MqttClientWebSocketOptions
MqttClientWebSocketOptions.CookieContainer	System.Net.CookieContainer
MqttClientWebSocketOptions.ProxyOptions	MQTTnet.Client.Options.MqttClientWebSocketProxyOptions
MqttClientWebSocketOptions.RequestHeaders	System.Collections.Generic.IDictionary<System.String, System.String>
MqttClientWebSocketOptions.SubProtocols	System.Collections.Generic.ICollection<System.String>	Default is { "mqtt" }.
MqttClientWebSocketOptions.TlsOptions	MQTTnet.Client.Options.MqttClientTlsOptions	For "ws", "wss" URL schemes, some sub-properties (described here) get overridden.
MqttClientWebSocketOptions.TlsOptions. AllowUntrustedCertificates	System.Boolean
MqttClientWebSocketOptions.TlsOptions.Certificates	System.List<System.Security.Cryptography.X509Certificates.X509Certificate> (.NET Framework) System.List<System.Byte[]> (.NET Standard)	For "wss" URL scheme, may get overridden by hosting software.
MqttClientWebSocketOptions.TlsOptions. CertificateValidationCallback	System.Func<System.Security.Cryptography.X509Certificates.X509Certificate, System.Security.Cryptography.X509Certificates.X509Chain, System.Net.Security.SslPolicyErrors, MQTTnet.Client.Options.IMqttClientOptions, System.Boolean>	For "wss" URL scheme, may get overridden by hosting software.
MqttClientWebSocketOptions.TlsOptions. IgnoreCertificateChainErrors	System.Boolean
MqttClientWebSocketOptions.TlsOptions. IgnoreCertificateRevocationErrors	System.Boolean
MqttClientWebSocketOptions.TlsOptions.SslProtocol	System.Security.Authentication.SslProtocols	Default is Tls12.
MqttClientWebSocketOptions.TlsOptions.UseTls	System.Boolean	Gets overridden to false for "ws" URL scheme, gets overridden to true for "wss" URL scheme.
MqttClientWebSocketOptions.Uri	System.String	For "ws", "wss" URL schemes, gets overridden by the input URL string.

Server (broker) role

Not implemented. In development. The type name of the message channel object is: OpcLabs.MqttNet.ManagedMqttServerMessageChannel,OpcLabs.MqttNet .

See also

Certificate security plugin