MQTTBroker Component

Properties Methods Events Config Settings Errors

A lightweight, fully-featured MQTT broker implementation.

Syntax

TiotMQTTBroker

Remarks

The MQTTBroker component provides a lightweight, fully-featured MQTT broker implementation with support for version 3.1.1. The component supports plaintext and TLS-enabled connections over both standard TCP and WebSockets.

Configuring Listeners

The AddBrokerListener method adds a new listener to the Listeners collection. Any listeners must be configured before starting the broker. Multiple protocols can be supported by adding different listeners.

The component supports the following protocols:


0 (mbpTCP)	Plaintext TCP
1 (mbpTLS)	SSL/TLS over TCP
2 (mbpWS)	Plaintext WebSocket
3 (mbpWSS)	SSL/TLS over WebSocket

Multiple protocols can be enabled (each on a different port):

C# Copy
// Plaintext TCP
mqttbroker.AddBrokerListener("127.0.0.1", PLAIN_PORT, (int)MQTTBrokerProtocols.mbpTCP, 0, null, null, null);
// TCP with TLS
mqttbroker.AddBrokerListener("127.0.0.1", SSL_PORT, (int)MQTTBrokerProtocols.mbpTLS, (int)CertStoreTypes.cstPFXFile, "test1.pfx", "test", "*");
// Plaintext WebSocket
mqttbroker.AddBrokerListener("127.0.0.1", WS_PORT, (int)MQTTBrokerProtocols.mbpWS, 0, null, null, null);
// WebSocket with TLS
mqttbroker.AddBrokerListener("127.0.0.1", WSS_PORT, (int)MQTTBrokerProtocols.mbpWSS, (int)CertStoreTypes.cstPFXFile, "test2.pfx", "test", "*");

Once all listeners have been added, the broker can be started via the StartListening method.

Handling Sessions

When an MQTT client requests a session, the SessionRequest event will fire with session details. The UserName and Password parameters can be checked before setting Accept to True to accept the session request. Accept can be set to False to reject the session request.

C# Copy
broker.OnSessionRequest += (s,e) => {
  // Check e.UserName and e.Password if needed
  // Set Accept to true to accept the session request
  e.Accept = true; 
};

Handling Subscriptions

When an MQTT client requests to subscribe to a topic, the Subscribe event will fire.

The ClientId is used to identify this client in subsequent actions.

The TopicFilter is the requested topic the client wishes to subscribe to.

The RequestedQoS is the client's preferred QoS level.

ReturnCode is used to confirm the maximum QoS level granted for this subscription or indicate a failure. This can be less than the client's RequestedQoS.


0x00	Success - Maximum QoS 0
0x01	Success - Maximum QoS 1
0x02	Success - Maximum QoS 2
0x80	Failure

When a client requests to unsubscribe from a topic, the Unsubscribe event will fire, specifying which TopicFilter the client is unsubscribing from.

Incoming Messages

The MQTTBroker component will automatically forward received messages to any subscribed clients. Events can be used to record the state of any incoming messages.

The MessageReceiving event fires when a message is initially received and contains message metadata.

The IncomingMessageStatus event fires each time an incoming message's state is updated.

MessageId: A unique identifier for this message.
DUP: Whether or not the server has indicated that this message is a duplicate of another message received previously.
QoS: The message's QoS level.
Retain: Whether or not this message was received as a result of subscribing to a topic.
PacketId: The message packet Id. This will always be -1 if QoS is 0.
State: Information about the incoming message's state.
- 6 - For an incoming QoS 1 message, which has been received from the client, but prior to sending the PUBACK for it. When the PUBACK is sent, the state will change to 10.
- 7 - For an incoming QoS 2 message, which has been received from a client, but prior to sending the PUBREC for it,
- 8 - For an incoming QoS 2 message, which has sent the PUBREC, but waiting to receive the PUBREL for it.
- 9 - For an incoming QoS 2 message, which has received the PUBREL, but prior to sending the PUBCOMP for it. When the PUBCOMP is sent, the state will change to 10.
- 10 - Message successfully received.

The MessageReceived event fires when the message has completed the acknowledgment process with the client, depending on the QoS level.

Outgoing Messages

The MQTTBroker component will automatically forward received messages to any subscribed clients. Events can be used to record the state of any incoming messages.

The MessageSending event fires when a message is initially sent to a client and contains message metadata.

The OutgoingMessageStatus event fires each time an outgoing message's state is updated.

MessageId: A unique identifier for this message.
DUP: Whether or not the server has indicated that this message is a duplicate of another message sent previously.
QoS: The message's QoS level.
Retain: Whether or not this message is a retained message.
PacketId: The message packet Id. This will always be -1 if QoS is 0.
State: Information about the outgoing message's state.
- 1 - Outgoing message is waiting to be sent
- 2 - For an outgoing QoS 1 message, which has been sent to the client and waiting for the PUBACK. When the PUBACK is received, the state will change to 10.
- 3 - For an outgoing QoS 2 message, which has been sent to the client and waiting for the PUBREC.
- 4 - For an outgoing QoS 2 message, which has received the PUBREC, prior to sending the PUBREL for it.
- 5 - For an outgoing QoS 2 message, which has sent the PUBREL. When the PUBCOMP is received, the state will change to 10.
- 10 - Message successfully sent.

Saving and Loading Sessions

The SaveSession method saves the current state of a client session, including message queues and subscription data, for later retrieval.

SaveSession returns a JSON string representing the client's subscriptions and messages. This can later be loaded via LoadSession to restore the client's state.

The format should be a JSON string with the following parameters:

C# Copy
string sessiondata = broker.SaveSession("Client1");
// sessiondata may contain a JSON string with information like this:
{
  "ClientId":"Client1",   
  "Subscriptions":[{      // A collection of the client's subscribed topics
    "Topic":"topic name",
    "QoS":2,
  }],
  "IncomingMessages": [{  // A collection of incoming messages
    "MessageId":1,        // The incoming message's ID
    "Topic":"A",          // The incoming message's topic
    "Payload":"54657374", // hexadecimal message payload
    "QoS":2,              // The incoming message's QoS level
    "DUP":false,          // Whether this message is a duplicate
    "Retain":false,       // Whether this is a retained message
    "PacketId":1,         // This message's packet ID
    "State":3             // See IncomingMessageStatus event for State details
    }],
  "OutgoingMessages":[{   // A collection of outgoing messages
    "MessageId":2,
    "Topic":"A",
    "Payload":"54657374",
    "QoS":2,
    "DUP":false,
    "Retain":false,
    "PacketId":2,
    "State":3             // See OutgoingMessageStatus event for State details
    }]
}
// Later, the LoadSession method can be used to load the session data
broker.LoadSession(sessiondata);

Property List

The following is the full list of the properties of the component with short descriptions. Click on the links for further details.


Connections	A collection of currently connected clients.
DefaultIdleTimeout	This property includes the default idle timeout for inactive clients.
Listeners	Defines the set of network endpoints where the MQTT Broker listens for client connections.
Listening	This property indicates whether the component is listening for incoming connections on LocalPort.
Messages	Provides a collection of retained messages available to newly subscribed clients.
Sessions	Contains session information for clients.
SSLProvider	The Secure Sockets Layer/Transport Layer Security (SSL/TLS) implementation to use.

Method List

The following is the full list of the methods of the component with short descriptions. Click on the links for further details.


AddBrokerListener	Creates a new listener for the broker service.
Config	Sets or retrieves a configuration setting.
Disconnect	This method disconnects the specified client.
DoEvents	This method processes events from the internal message queue.
Interrupt	This method interrupts a synchronous send to the remote host.
LoadSession	Restores session data for a specified client, enabling resumption of pending operations or message delivery.
Reset	This method will reset the component.
SaveSession	Saves the current state of a client session, including message queues and subscription data, for later retrieval.
Shutdown	This method shuts down the server.
StartListening	This method starts listening for incoming connections.
StopListening	This method stops listening for new connections.

Event List

The following is the full list of the events fired by the component with short descriptions. Click on the links for further details.


Connected	This event is fired immediately after a connection completes (or fails).
ConnectionRequest	This event is fired when a request for connection comes from a remote host.
Disconnected	This event is fired when a connection is closed.
Error	This event fires information about errors during data delivery.
IncomingMessageStatus	Fires when an incoming message's state is updated.
Log	Fires once for each log message.
MessageReceived	Fires when a new message is received from a client.
MessageReceiving	Fires when a message is initially received from a client.
MessageSending	Fires when a message is initially sent to a client.
MessageSent	Fires after a message is successfully delivered to a client, confirming transmission.
OutgoingMessageStatus	Fired to provide the current delivery status of an outgoing message. Includes success or failure metadata.
SessionRemoved	Fired when a client session is removed, indicating all resources associated with the session are cleaned up.
SessionRequest	Fires when a new session is requested.
SSLClientAuthentication	This event is fired when the client presents its credentials to the server.
SSLStatus	This event is fired to show the progress of the secure connection.
Subscribe	Fires when a client requests to subscribe to a topic.
Unsubscribe	Fires when a client unsubscribes from a topic, removing its subscription data.

Config Settings

The following is a list of config settings for the component with short descriptions. Click on the links for further details.


CloseStreamAfterTransfer	If true, the component will close the upload or download stream after the transfer.
ConnectionTimeout	Sets a separate timeout value for establishing a connection.
FirewallAutoDetect	Tells the component whether or not to automatically detect and use firewall system settings, if available.
FirewallHost	Name or IP address of firewall (optional).
FirewallPassword	Password to be used if authentication is to be used when connecting through the firewall.
FirewallPort	The TCP port for the FirewallHost;.
FirewallType	Determines the type of firewall to connect through.
FirewallUser	A user name if authentication is to be used connecting through a firewall.
KeepAliveInterval	The retry interval, in milliseconds, to be used when a TCP keep-alive packet is sent and no response is received.
KeepAliveTime	The inactivity time in milliseconds before a TCP keep-alive packet is sent.
Linger	When set to True, connections are terminated gracefully.
LingerTime	Time in seconds to have the connection linger.
LocalHost	The name of the local host through which connections are initiated or accepted.
LocalPort	The port in the local host where the component binds.
MaxLineLength	The maximum amount of data to accumulate when no EOL is found.
MaxTransferRate	The transfer rate limit in bytes per second.
ProxyExceptionsList	A semicolon separated list of hosts and IPs to bypass when using a proxy.
TCPKeepAlive	Determines whether or not the keep alive socket option is enabled.
TcpNoDelay	Whether or not to delay when sending packets.
UseIPv6	Whether to use IPv6.
LogSSLPackets	Controls whether SSL packets are logged when using the internal security API.
OpenSSLCADir	The path to a directory containing CA certificates.
OpenSSLCAFile	Name of the file containing the list of CA's trusted by your application.
OpenSSLCipherList	A string that controls the ciphers to be used by SSL.
OpenSSLPrngSeedData	The data to seed the pseudo random number generator (PRNG).
ReuseSSLSession	Determines if the SSL session is reused.
SSLCACerts	A newline separated list of CA certificates to be included when performing an SSL handshake.
SSLCheckCRL	Whether to check the Certificate Revocation List for the server certificate.
SSLCheckOCSP	Whether to use OCSP to check the status of the server certificate.
SSLCipherStrength	The minimum cipher strength used for bulk encryption.
SSLClientCACerts	A newline separated list of CA certificates to use during SSL client certificate validation.
SSLEnabledCipherSuites	The cipher suite to be used in an SSL negotiation.
SSLEnabledProtocols	Used to enable/disable the supported security protocols.
SSLEnableRenegotiation	Whether the renegotiation_info SSL extension is supported.
SSLIncludeCertChain	Whether the entire certificate chain is included in the SSLServerAuthentication event.
SSLKeyLogFile	The location of a file where per-session secrets are written for debugging purposes.
SSLNegotiatedCipher	Returns the negotiated cipher suite.
SSLNegotiatedCipherStrength	Returns the negotiated cipher suite strength.
SSLNegotiatedCipherSuite	Returns the negotiated cipher suite.
SSLNegotiatedKeyExchange	Returns the negotiated key exchange algorithm.
SSLNegotiatedKeyExchangeStrength	Returns the negotiated key exchange algorithm strength.
SSLNegotiatedVersion	Returns the negotiated protocol version.
SSLSecurityFlags	Flags that control certificate verification.
SSLServerCACerts	A newline separated list of CA certificates to use during SSL server certificate validation.
TLS12SignatureAlgorithms	Defines the allowed TLS 1.2 signature algorithms when SSLProvider is set to Internal.
TLS12SupportedGroups	The supported groups for ECC.
TLS13KeyShareGroups	The groups for which to pregenerate key shares.
TLS13SignatureAlgorithms	The allowed certificate signature algorithms.
TLS13SupportedGroups	The supported groups for (EC)DHE key exchange.
AbsoluteTimeout	Determines whether timeouts are inactivity timeouts or absolute timeouts.
FirewallData	Used to send extra data to the firewall.
InBufferSize	The size in bytes of the incoming queue of the socket.
OutBufferSize	The size in bytes of the outgoing queue of the socket.
BuildInfo	Information about the product's build.
CodePage	The system code page used for Unicode to Multibyte translations.
LicenseInfo	Information about the current license.
MaskSensitiveData	Whether sensitive data is masked in log messages.
UseFIPSCompliantAPI	Tells the component whether or not to use FIPS certified APIs.
UseInternalSecurityAPI	Whether or not to use the system security libraries or an internal implementation.

Connections Property (MQTTBroker Component)

A collection of currently connected clients.

Syntax

property Connections: TiotMQTTBrokerConnectionList read get_Connections;

Remarks

This property contains a collection of currently connected clients. All of the connections may be managed using this property. Each connection is described by the different fields of the Connection type.

This collection is a hash-table type of collection, in which the Connection Id string is used as the key to the desired connection. You may acquire the key for a given connection through the Connected event.

This property is read-only and not available at design time.

Please refer to the MQTTBrokerConnection type for a complete list of fields.

DefaultIdleTimeout Property (MQTTBroker Component)

This property includes the default idle timeout for inactive clients.

Syntax

property DefaultIdleTimeout: Integer read get_DefaultIdleTimeout write set_DefaultIdleTimeout;

Default Value

Remarks

This property specifies the idle timeout (in seconds) for clients. When set to a positive value, the component will disconnect idle clients after the specified timeout.

This applies only to clients that have not sent or received data within DefaultIdleTimeout seconds.

If set to 0 (default), no idle timeout is applied.

Note: DoEvents must be called for the component to check existing connections.

Listeners Property (MQTTBroker Component)

Defines the set of network endpoints where the MQTT Broker listens for client connections.

Syntax

property Listeners: TiotMQTTBrokerListenerList read get_Listeners;

Remarks

Each listener is represented by an endpoint structure, including IP address and port. This allows fine-grained control over accessibility and security, enabling the broker to serve clients on different networks or with different protocols.

This property is read-only and not available at design time.

Please refer to the MQTTBrokerListener type for a complete list of fields.

Listening Property (MQTTBroker Component)

This property indicates whether the component is listening for incoming connections on LocalPort.

Syntax

property Listening: Boolean read get_Listening;

Default Value

false

Remarks

This property indicates whether the component is listening for connections on the port specified by the LocalPort property. Use the StartListening and StopListening methods to control whether the component is listening.

This property is read-only and not available at design time.

Messages Property (MQTTBroker Component)

Provides a collection of retained messages available to newly subscribed clients.

Syntax

property Messages: TiotMQTTBrokerMessageList read get_Messages;

Remarks

Retained messages are stored and delivered to clients subscribing to their respective topics. This property allows inspection and management of retained messages, including adding, modifying, or removing messages for specific topics.

This property is read-only and not available at design time.

Please refer to the MQTTBrokerMessage type for a complete list of fields.

Sessions Property (MQTTBroker Component)

Contains session information for clients.

Syntax

property Sessions: TiotMQTTBrokerSessionList read get_Sessions;

Remarks

Session data includes stored messages, subscription topics, and QoS levels. This ensures that messages are delivered even if a client reconnects after a disconnection.

This property is read-only and not available at design time.

Please refer to the MQTTBrokerSession type for a complete list of fields.

SSLProvider Property (MQTTBroker Component)

The Secure Sockets Layer/Transport Layer Security (SSL/TLS) implementation to use.

Syntax

property SSLProvider: TiotTSSLProviders read get_SSLProvider write set_SSLProvider;

TiotTSSLProviders = (
  sslpAutomatic,
  sslpPlatform,
  sslpInternal
);

Default Value

sslpAutomatic

Remarks

This property specifies the SSL/TLS implementation to use. In most cases the default value of 0 (Automatic) is recommended and should not be changed. When set to 0 (Automatic), the component will select whether to use the platform implementation or the internal implementation depending on the operating system as well as the TLS version being used.

Possible values are as follows:


0 (sslpAutomatic - default)	Automatically selects the appropriate implementation.
1 (sslpPlatform)	Uses the platform/system implementation.
2 (sslpInternal)	Uses the internal implementation.

Additional Notes

In most cases using the default value (Automatic) is recommended. The component will select a provider depending on the current platform.

When Automatic is selected, on Windows, the component will use the platform implementation. On Linux/macOS, the component will use the internal implementation. When TLS 1.3 is enabled via SSLEnabledProtocols, the internal implementation is used on all platforms.

AddBrokerListener Method (MQTTBroker Component)

Creates a new listener for the broker service.

Syntax

procedure AddBrokerListener(LocalHost: String; LocalPort: Integer; Protocol: Integer; SSLCertStoreType: Integer; SSLCertStore: TBytes; SSLCertStorePassword: String; SSLCertSubject: String);

Remarks

AddBrokerListener adds a new listener to the Listeners collection. Any listeners must be configured before starting the broker. Multiple protocols can be supported by adding different listeners.

The component supports the following protocols:


0 (mbpTCP)	Plaintext TCP
1 (mbpTLS)	SSL/TLS over TCP
2 (mbpWS)	Plaintext WebSocket
3 (mbpWSS)	SSL/TLS over WebSocket

Certificate details can be provided via the following parameters:


SSLCertStoreType	The type of certificate store for this certificate.
SSLCertStore	The name of the certificate store for the client certificate. This can be null for plaintext.
SSLCertStorePassword	If the type of certificate store requires a password, this field is used to specify the password needed to open the certificate store.
SSLCertSubject	The subject of the certificate used for client authentication.

Multiple protocols can be enabled (each on a different port):

C# Copy
// Plaintext TCP
mqttbroker.AddBrokerListener("127.0.0.1", PLAIN_PORT, (int)MQTTBrokerProtocols.mbpTCP, 0, null, null, null);
// TCP with TLS
mqttbroker.AddBrokerListener("127.0.0.1", SSL_PORT, (int)MQTTBrokerProtocols.mbpTLS, (int)CertStoreTypes.cstPFXFile, "test1.pfx", "test", "*");
// Plaintext WebSocket
mqttbroker.AddBrokerListener("127.0.0.1", WS_PORT, (int)MQTTBrokerProtocols.mbpWS, 0, null, null, null);
// WebSocket with TLS
mqttbroker.AddBrokerListener("127.0.0.1", WSS_PORT, (int)MQTTBrokerProtocols.mbpWSS, (int)CertStoreTypes.cstPFXFile, "test2.pfx", "test", "*");

Config Method (MQTTBroker Component)

Sets or retrieves a configuration setting.

Syntax

function Config(ConfigurationString: String): String;

Remarks

Config is a generic method available in every component. It is used to set and retrieve configuration settings for the component.

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the component, access to these internal properties is provided through the Config method.

To set a configuration setting named PROPERTY, you must call Config("PROPERTY=VALUE"), where VALUE is the value of the setting expressed as a string. For boolean values, use the strings "True", "False", "0", "1", "Yes", or "No" (case does not matter).

To read (query) the value of a configuration setting, you must call Config("PROPERTY"). The value will be returned as a string.

Disconnect Method (MQTTBroker Component)

This method disconnects the specified client.

Syntax

procedure Disconnect(ConnectionId: Integer);

Remarks

Calling this method will disconnect the client specified by the ConnectionId parameter.

DoEvents Method (MQTTBroker Component)

This method processes events from the internal message queue.

Syntax

procedure DoEvents();

Remarks

When DoEvents is called, the component processes any available events. If no events are available, it waits for a preset period of time, and then returns.

Interrupt Method (MQTTBroker Component)

This method interrupts a synchronous send to the remote host.

Syntax

procedure Interrupt(ConnectionId: Integer);

Remarks

This property is called using the Connection Id if you wish to interrupt a connection and stop a file from uploading without disconnecting the client connected to the component. If you use SendFile to upload a file, the component will run synchronously on that Connection Id until it is completed.

LoadSession Method (MQTTBroker Component)

Restores session data for a specified client, enabling resumption of pending operations or message delivery.

Syntax

procedure LoadSession(sessionInfo: String);

Remarks

The LoadSession method is used to load prior client session information if required. This can be used after shutting down a broker to preserve session data and ensure messages can be redelivered once the broker is restarted.

The SaveSession method can be used to save session data, and the resulting string can be provided to the LoadSession method.

The format should be a JSON string with the following parameters:

C# Copy
{
  "ClientId":"Client1",   
  "Subscriptions":[{      // A collection of the client's subscribed topics
    "Topic":"topic name",
    "QoS":2,
  }],
  "IncomingMessages": [{  // A collection of incoming messages
    "MessageId":1,        // The incoming message's ID
    "Topic":"A",          // The incoming message's topic
    "Payload":"54657374", // hexadecimal message payload
    "QoS":2,              // The incoming message's QoS level
    "DUP":false,          // Whether this message is a duplicate
    "Retain":false,       // Whether this is a retained message
    "PacketId":1,         // This message's packet ID
    "State":3             // See IncomingMessageStatus event for State details
    }],
  "OutgoingMessages":[{   // A collection of outgoing messages
    "MessageId":2,
    "Topic":"A",
    "Payload":"54657374",
    "QoS":2,
    "DUP":false,
    "Retain":false,
    "PacketId":2,
    "State":3             // See OutgoingMessageStatus event for State details
    }]
}

Session data can be saved with SaveSession, then later loaded with LoadSession

C# Copy
string sessiondata = broker.SaveSession("Client1");
// sessiondata contains session information for Client1 
...
broker.LoadSession(sessiondata);

Reset Method (MQTTBroker Component)

This method will reset the component.

Syntax

procedure Reset();

Remarks

This method will reset the component's properties to their default values.

SaveSession Method (MQTTBroker Component)

Saves the current state of a client session, including message queues and subscription data, for later retrieval.

Syntax

function SaveSession(clientId: String): String;

Remarks

Returns a JSON string representing the client's subscriptions and messages. This can later be loaded via LoadSession to restore the client's state.

The format should be a JSON string with the following parameters:

C# Copy
string sessiondata = broker.SaveSession("Client1");
// sessiondata may contain a JSON string with information like this:
{
  "ClientId":"Client1",   
  "Subscriptions":[{      // A collection of the client's subscribed topics
    "Topic":"topic name",
    "QoS":2,
  }],
  "IncomingMessages": [{  // A collection of incoming messages
    "MessageId":1,        // The incoming message's ID
    "Topic":"A",          // The incoming message's topic
    "Payload":"54657374", // hexadecimal message payload
    "QoS":2,              // The incoming message's QoS level
    "DUP":false,          // Whether this message is a duplicate
    "Retain":false,       // Whether this is a retained message
    "PacketId":1,         // This message's packet ID
    "State":3             // See IncomingMessageStatus event for State details
    }],
  "OutgoingMessages":[{   // A collection of outgoing messages
    "MessageId":2,
    "Topic":"A",
    "Payload":"54657374",
    "QoS":2,
    "DUP":false,
    "Retain":false,
    "PacketId":2,
    "State":3             // See OutgoingMessageStatus event for State details
    }]
}

Shutdown Method (MQTTBroker Component)

This method shuts down the server.

Syntax

procedure Shutdown();

Remarks

This method shuts down the server. Calling this method is equivalent to calling StopListening and then breaking every client connection by calling Disconnect.

StartListening Method (MQTTBroker Component)

This method starts listening for incoming connections.

Syntax

procedure StartListening();

Remarks

This method begins listening for incoming connections on the port specified by LocalPort. Once listening, events will fire as new clients connect and data are transferred.

To stop listening for new connections, call StopListening. To stop listening for new connections and to disconnect all existing clients, call Shutdown.

StopListening Method (MQTTBroker Component)

This method stops listening for new connections.

Syntax

procedure StopListening();

Remarks

This method stops listening for new connections. After being called, any new connection attempts will be rejected. Calling this method does not disconnect existing connections.

To stop listening and to disconnect all existing clients, call Shutdown instead.

Connected Event (MQTTBroker Component)

This event is fired immediately after a connection completes (or fails).

Syntax

type TConnectedEvent = procedure (
  Sender: TObject;
  ConnectionId: Integer;
  StatusCode: Integer;
  const Description: String
) of Object;

property OnConnected: TConnectedEvent read FOnConnected write FOnConnected;

Remarks

If the connection is made normally, StatusCode is 0, and Description is 'OK'.

If the connection fails, StatusCode has the error code returned by the system. Description contains a description of this code. The value of StatusCode is equal to the value of the system error.

Please refer to the Error Codes section for more information.

ConnectionRequest Event (MQTTBroker Component)

This event is fired when a request for connection comes from a remote host.

Syntax

type TConnectionRequestEvent = procedure (
  Sender: TObject;
  const Address: String;
  Port: Integer;
  var Accept: Boolean
) of Object;

property OnConnectionRequest: TConnectionRequestEvent read FOnConnectionRequest write FOnConnectionRequest;

Remarks

This event indicates an incoming connection. The connection is accepted by default. Address and Port will contain information about the remote host requesting the inbound connection. If you want to refuse it, you can set the Accept parameter to False.

Disconnected Event (MQTTBroker Component)

This event is fired when a connection is closed.

Syntax

type TDisconnectedEvent = procedure (
  Sender: TObject;
  ConnectionId: Integer;
  StatusCode: Integer;
  const Description: String
) of Object;

property OnDisconnected: TDisconnectedEvent read FOnDisconnected write FOnDisconnected;

Remarks

If the connection is broken normally, StatusCode is 0, and Description is 'OK'.

If the connection is broken for any other reason, StatusCode has the error code returned by the system. Description contains a description of this code. The value of StatusCode is equal to the value of the system error.

Please refer to the Error Codes section for more information.

Error Event (MQTTBroker Component)

This event fires information about errors during data delivery.

Syntax

type TErrorEvent = procedure (
  Sender: TObject;
  ConnectionId: Integer;
  ErrorCode: Integer;
  const Description: String
) of Object;

property OnError: TErrorEvent read FOnError write FOnError;

Remarks

The Error event is fired in case of exceptional conditions during message processing. Normally, the component raises an exception.

ErrorCode contains an error code and Description contains a textual description of the error. For a list of valid error codes and their descriptions, please refer to the Error Codes section.

ConnectionId indicates the connection for which the error is applicable.

IncomingMessageStatus Event (MQTTBroker Component)

Fires when an incoming message's state is updated.

Syntax

type TIncomingMessageStatusEvent = procedure (
  Sender: TObject;
  ConnectionId: Integer;
  const ClientId: String;
  MessageId: Int64;
  DUP: Boolean;
  QoS: Integer;
  Retain: Boolean;
  PacketId: Integer;
  State: Integer
) of Object;

property OnIncomingMessageStatus: TIncomingMessageStatusEvent read FOnIncomingMessageStatus write FOnIncomingMessageStatus;

Remarks

The IncomingMessageStatus event fires each time an incoming message's state is updated.

MessageId: A unique identifier for this message.
DUP: Whether or not the server has indicated that this message is a duplicate of another message received previously.
QoS: The message's QoS level.
Retain: Whether or not this message was received as a result of subscribing to a topic.
PacketId: The message packet Id. This will always be -1 if QoS is 0.
State: Information about the incoming message's state.
- 6 - For an incoming QoS 1 message, which has been received from the client, but prior to sending the PUBACK for it. When the PUBACK is sent, the state will change to 10.
- 7 - For an incoming QoS 2 message, which has been received from a client, but prior to sending the PUBREC for it,
- 8 - For an incoming QoS 2 message, which has sent the PUBREC, but waiting to receive the PUBREL for it.
- 9 - For an incoming QoS 2 message, which has received the PUBREL, but prior to sending the PUBCOMP for it. When the PUBCOMP is sent, the state will change to 10.
- 10 - Message successfully received.

Log Event (MQTTBroker Component)

Fires once for each log message.

Syntax

type TLogEvent = procedure (
  Sender: TObject;
  ConnectionId: Integer;
  LogLevel: Integer;
  const Message: String;
  const LogType: String
) of Object;

property OnLog: TLogEvent read FOnLog write FOnLog;

Remarks

This event fires once for each log message generated by the component. The verbosity is controlled by the LogLevel setting.

LogLevel indicates the level of the Message. Possible values are:


0 (None)	No events are logged.
1 (Info - default)	Informational events are logged.
2 (Verbose)	Detailed data is logged.
3 (Debug)	Debug data is logged.

LogType identifies the type of log entry. Possible values are:

Info: General information about the component.
Session: Session status messages.
Frame: Frame status messages.

MessageReceived Event (MQTTBroker Component)

Fires when a new message is received from a client.

Syntax

type TMessageReceivedEvent = procedure (
  Sender: TObject;
  ConnectionId: Integer;
  const ClientId: String;
  MessageId: Int64
) of Object;

property OnMessageReceived: TMessageReceivedEvent read FOnMessageReceived write FOnMessageReceived;

Remarks

This event fires each time a message is received from a client.

MessageReceiving Event (MQTTBroker Component)

Fires when a message is initially received from a client.

Syntax

type TMessageReceivingEvent = procedure (
  Sender: TObject;
  ConnectionId: Integer;
  const ClientId: String;
  MessageId: Int64;
  DUP: Boolean;
  QoS: Integer;
  Retain: Boolean;
  PacketId: Integer
) of Object;

property OnMessageReceiving: TMessageReceivingEvent read FOnMessageReceiving write FOnMessageReceiving;

Remarks

The MessageReceiving event fires once for each incoming message immediately after it is received from a client.

MessageId: A unique identifier for this message.
DUP: Whether or not the server has indicated that this message is a duplicate of another message sent previously.
QoS: The message's QoS level.
Retain: Whether or not this message was received as a result of subscribing to a topic.
PacketId: The message packet Id. This will always be -1 if QoS is 0.

MessageSending Event (MQTTBroker Component)

Fires when a message is initially sent to a client.

Syntax

type TMessageSendingEvent = procedure (
  Sender: TObject;
  ConnectionId: Integer;
  const ClientId: String;
  MessageId: Int64;
  DUP: Boolean;
  QoS: Integer;
  Retain: Boolean;
  PacketId: Integer
) of Object;

property OnMessageSending: TMessageSendingEvent read FOnMessageSending write FOnMessageSending;

Remarks

The MessageSending fires once for each outgoing message immediately after it is sent to a client.

MessageId: A unique identifier for this message.
DUP: Whether or not the server has indicated that this message is a duplicate of another message sent previously.
QoS: The message's QoS level.
Retain: Whether or not this message was received as a result of subscribing to a topic.
PacketId: The message packet Id. This will always be -1 if QoS is 0.

MessageSent Event (MQTTBroker Component)

Fires after a message is successfully delivered to a client, confirming transmission.

Syntax

type TMessageSentEvent = procedure (
  Sender: TObject;
  ConnectionId: Integer;
  const ClientId: String;
  MessageId: Int64
) of Object;

property OnMessageSent: TMessageSentEvent read FOnMessageSent write FOnMessageSent;

Remarks

This event fires each time a message is delivered to a client.

OutgoingMessageStatus Event (MQTTBroker Component)

Fired to provide the current delivery status of an outgoing message. Includes success or failure metadata.

Syntax

type TOutgoingMessageStatusEvent = procedure (
  Sender: TObject;
  ConnectionId: Integer;
  const ClientId: String;
  MessageId: Int64;
  DUP: Boolean;
  QoS: Integer;
  Retain: Boolean;
  PacketId: Integer;
  State: Integer
) of Object;

property OnOutgoingMessageStatus: TOutgoingMessageStatusEvent read FOnOutgoingMessageStatus write FOnOutgoingMessageStatus;

Remarks

The OutgoingMessageStatus event fires each time an outgoing message's state is updated.

MessageId: A unique identifier for this message.
DUP: Whether or not the server has indicated that this message is a duplicate of another message sent previously.
QoS: The message's QoS level.
Retain: Whether or not this message is a retained message.
PacketId: The message packet Id. This will always be -1 if QoS is 0.
State: Information about the outgoing message's state.
- 1 - Outgoing message is waiting to be sent
- 2 - For an outgoing QoS 1 message, which has been sent to the client and waiting for the PUBACK. When the PUBACK is received, the state will change to 10.
- 3 - For an outgoing QoS 2 message, which has been sent to the client and waiting for the PUBREC.
- 4 - For an outgoing QoS 2 message, which has received the PUBREC, prior to sending the PUBREL for it.
- 5 - For an outgoing QoS 2 message, which has sent the PUBREL. When the PUBCOMP is received, the state will change to 10.
- 10 - Message successfully sent.

SessionRemoved Event (MQTTBroker Component)

Fired when a client session is removed, indicating all resources associated with the session are cleaned up.

Syntax

type TSessionRemovedEvent = procedure (
  Sender: TObject;
  const ClientId: String
) of Object;

property OnSessionRemoved: TSessionRemovedEvent read FOnSessionRemoved write FOnSessionRemoved;

Remarks

The client with the associated ClientId will also be removed from the Sessions collection when this event returns.

SessionRequest Event (MQTTBroker Component)

Fires when a new session is requested.

Syntax

type TSessionRequestEvent = procedure (
  Sender: TObject;
  ConnectionId: Integer;
  const ClientId: String;
  const UserName: String;
  const Password: String;
  IsNew: Boolean;
  var Accept: Boolean
) of Object;

property OnSessionRequest: TSessionRequestEvent read FOnSessionRequest write FOnSessionRequest;

Remarks

UserName and Password contain authentication credentials which can be verified in this event.

IsNew denotes whether this is a clean session from the client.

Accept can be set to false to reject the client. Set Accept to true to accept this client.

Example:

C# Copy
broker.OnSessionRequest += (s,e) => {
  // Check e.UserName and e.Password if needed
  // Set Accept to true to accept the session request
  e.Accept = true; 
};

SSLClientAuthentication Event (MQTTBroker Component)

This event is fired when the client presents its credentials to the server.

Syntax

type TSSLClientAuthenticationEvent = procedure (
  Sender: TObject;
  ConnectionId: Integer;
  const CertEncoded: String;
  const CertEncodedB: TBytes;
  const CertSubject: String;
  const CertIssuer: String;
  const Status: String;
  var Accept: Boolean
) of Object;

property OnSSLClientAuthentication: TSSLClientAuthenticationEvent read FOnSSLClientAuthentication write FOnSSLClientAuthentication;

Remarks

This event enables the server to decide whether or not to continue. The Accept parameter is a recommendation on whether to continue or to close the connection. This is just a suggestion: application software must use its own logic to determine whether or not to continue.

When Accept is False, Status shows why the verification failed (otherwise, Status contains the string "OK").

SSLStatus Event (MQTTBroker Component)

This event is fired to show the progress of the secure connection.

Syntax

type TSSLStatusEvent = procedure (
  Sender: TObject;
  ConnectionId: Integer;
  const Message: String
) of Object;

property OnSSLStatus: TSSLStatusEvent read FOnSSLStatus write FOnSSLStatus;

Remarks

The event is fired for informational and logging purposes only. It is used to track the progress of the connection.

Subscribe Event (MQTTBroker Component)

Fires when a client requests to subscribe to a topic.

Syntax

type TSubscribeEvent = procedure (
  Sender: TObject;
  ConnectionId: Integer;
  const ClientId: String;
  const TopicFilter: String;
  RequestedQoS: Integer;
  var ReturnCode: Integer
) of Object;

property OnSubscribe: TSubscribeEvent read FOnSubscribe write FOnSubscribe;

Remarks

The ClientId is used to identify this client in subsequent actions.

The TopicFilter is the requested topic the client wishes to subscribe to.

The RequestedQoS is the client's preferred QoS level.

ReturnCode is used to confirm the maximum QoS level granted for this subscription or indicate a failure. This can be less than the client's RequestedQoS.


0x00	Success - Maximum QoS 0
0x01	Success - Maximum QoS 1
0x02	Success - Maximum QoS 2
0x80	Failure

Unsubscribe Event (MQTTBroker Component)

Fires when a client unsubscribes from a topic, removing its subscription data.

Syntax

type TUnsubscribeEvent = procedure (
  Sender: TObject;
  ConnectionId: Integer;
  const ClientId: String;
  const TopicFilter: String
) of Object;

property OnUnsubscribe: TUnsubscribeEvent read FOnUnsubscribe write FOnUnsubscribe;

Remarks

The TopicFilter shows the topic this client is unsubscribing from.

MQTTBrokerConnection Type

This is a currently connected client.

Remarks

This type describes the connection of a client that is currently connected to the component. You may use the different fields of this type to manage the connection.

The following fields are available:

ClientId
ConnectionId
KeepAlive
LocalHost
LocalPort
Protocol
RemoteHost
RemotePort
UserName

Fields

ClientId
String (read-only)
Default Value: ""

A unique identifier for the client.

ConnectionId
Integer (read-only)
Default Value: 0

This field contains an identifier generated by the component to identify each connection. This identifier is unique to this connection.

KeepAlive
Integer (read-only)
Default Value: 0

When set to 1, KEEPALIVE packets are enabled (for long connections).

This property enables the SO_KEEPALIVE option on the incoming connections. This option prevents long connections from timing out in case of inactivity.

Note: System Transmission Control Protocol (TCP)/IP stack implementations are not required to support SO_KEEPALIVE.

This property is shared among incoming connections. When the property is set, the corresponding value is set for incoming connections as they are accepted. Existing connections are not modified.

LocalHost
String (read-only)
Default Value: ""

This field shows the IP address of the interface through which the connection is passing.

LocalAddress is important for multihomed hosts so that it can be used to find the particular network interface through which an individual connection is going.

LocalPort
Integer (read-only)
Default Value: 0

This field shows the Transmission Control Protocol (TCP) port on the local host through which the connection is passing.

Protocol
TiotMQTTBrokerProtocols (read-only)
Default Value: 0

The protocol of the connected client.

The component supports the following protocols:


0 (mbpTCP)	Plaintext TCP
1 (mbpTLS)	SSL/TLS over TCP
2 (mbpWS)	Plaintext WebSocket
3 (mbpWSS)	SSL/TLS over WebSocket

RemoteHost
String (read-only)
Default Value: ""

This field shows the IP address of the remote host through which the connection is coming.

The connection must be valid or an error will be fired.

If the component is configured to use a SOCKS firewall, the value assigned to this property may be preceded with an "*". If this is the case, the host name is passed to the firewall unresolved and the firewall performs the DNS resolution.

RemotePort
Integer (read-only)
Default Value: 0

This field shows the Transmission Control Protocol (TCP) port on the remote host through which the connection is coming.

The connection must be valid or an error will be fired.

UserName
String (read-only)
Default Value: ""

The username for this connected client.

Constructors

constructor Create();

MQTTBrokerListener Type

This represents a broker listener.

Remarks

Multiple listeners can be configured to listen on different ports and protocols..

The following fields are available:

LocalHost
LocalPort
Protocol
SSLAuthenticateClients
SSLCertStore
SSLCertStorePassword
SSLCertStoreType
SSLCertSubject

Fields

LocalHost
String (read-only)
Default Value: ""

The name of the local host or user-assigned IP interface through which connections are initiated or accepted.

LocalPort
Integer (read-only)
Default Value: 0

This field includes the port in the local host for this listener.

Protocol
TiotMQTTBrokerProtocols (read-only)
Default Value: 0

The component supports the following protocols:


0 (mbpTCP)	Plaintext TCP
1 (mbpTLS)	SSL/TLS over TCP
2 (mbpWS)	Plaintext WebSocket
3 (mbpWSS)	SSL/TLS over WebSocket

SSLAuthenticateClients
Boolean (read-only)
Default Value: False

If set to True, the server asks the client(s) for a certificate.

This is used in conjunction with the SSLClientAuthentication event. Please refer to the documentation of the SSLClientAuthentication event for details.

SSLCertStore
String (read-only)
Default Value: "MY"

The name of the certificate store for the listener's certificate.

The StoreType property denotes the type of the certificate store specified by Store. If the store is password-protected, specify the password in StorePassword.

Store is used in conjunction with the Subject property to specify client certificates. If Store has a value, and Subject or Encoded is set, a search for a certificate is initiated. Please see the Subject property for details.

Designations of certificate stores are platform dependent.

The following designations are the most common User and Machine certificate stores in Windows:


MY	A certificate store holding personal certificates with their associated private keys.
CA	Certifying authority certificates.
ROOT	Root certificates.

When the certificate store type is cstPFXFile, this property must be set to the name of the file. When the type is cstPFXBlob, the property must be set to the binary contents of a PFX file (i.e., PKCS#12 certificate store).

SSLCertStoreB
TBytes (read-only)
Default Value: "MY"

The name of the certificate store for the listener's certificate.

The StoreType property denotes the type of the certificate store specified by Store. If the store is password-protected, specify the password in StorePassword.

Designations of certificate stores are platform dependent.

The following designations are the most common User and Machine certificate stores in Windows:


MY	A certificate store holding personal certificates with their associated private keys.
CA	Certifying authority certificates.
ROOT	Root certificates.

SSLCertStorePassword
String (read-only)
Default Value: ""

This is the password of the SSL certificate.

SSLCertStoreType
TiotCertStoreTypes (read-only)
Default Value: 0

This is the type of certificate store for this certificate.

Designations of certificate stores are platform dependent.

The following designations are the most common User and Machine certificate stores in Windows:


MY	A certificate store holding personal certificates with their associated private keys.
CA	Certifying authority certificates.
ROOT	Root certificates.

SSLCertSubject
String (read-only)
Default Value: ""

The subject of the SSL certificate.

The certificate subject is a comma-separated list of distinguished name fields and values. For instance, "CN=www.server.com, OU=test, C=US, E=support@nsoftware.com". Common fields and their meanings are as follows:


Field	Meaning
CN	Common Name. This is commonly a hostname like www.server.com.
O	Organization
OU	Organizational Unit
L	Locality
S	State
C	Country
E	Email Address

If a field value contains a comma, it must be quoted.

Constructors

constructor Create();

MQTTBrokerMessage Type

An MQTT message.

Remarks

This type represents an MQTT message.

The following fields are available:

MessageId
Payload
Topic

Fields

MessageId
Int64 (read-only)
Default Value: 0

Message identifier used to associate the message state.

Payload
String (read-only)
Default Value: ""

This message's raw data payload.

PayloadB
TBytes (read-only)
Default Value: ""

This message's raw data payload.

Topic
String (read-only)
Default Value: ""

This message's topic.

Constructors

constructor Create();

MQTTBrokerSession Type

Information for the client session.

Remarks

This contains session information for a client.

The following fields are available:

ClientId
IncomingMessages
OutgoingMessages
SubGrantedQoS
SubTopicFilters

Fields

ClientId
String (read-only)
Default Value: ""

A unique identifier for the client.

IncomingMessages
String (read-only)
Default Value: ""

A collection of incoming messages.

OutgoingMessages
String (read-only)
Default Value: ""

A collection of outgoing messages.

SubGrantedQoS
String (read-only)
Default Value: ""

The subscription's granted QoS level for the client.

SubTopicFilters
String (read-only)
Default Value: ""

The subscription topic filters for this client session.

Constructors

constructor Create();

Config Settings (MQTTBroker Component)

The component accepts one or more of the following configuration settings. Configuration settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the component, access to these internal properties is provided through the Config method.

TCPClient Config Settings

CloseStreamAfterTransfer: If true, the component will close the upload or download stream after the transfer.

This configuration setting determines whether the input or output stream is closed after the transfer completes. When set to True (default), all streams will be closed after a transfer is completed. To keep streams open after the transfer of data, set this to False. The default value is True.

ConnectionTimeout: Sets a separate timeout value for establishing a connection.

When set, this configuration setting allows you to specify a different timeout value for establishing a connection. Otherwise, the component will use Timeout for establishing a connection and transmitting/receiving data.

FirewallAutoDetect: Tells the component whether or not to automatically detect and use firewall system settings, if available.

This configuration setting is provided for use by components that do not directly expose Firewall properties.

FirewallHost: Name or IP address of firewall (optional).

If a FirewallHost is given, requested connections will be authenticated through the specified firewall when connecting.

If the FirewallHost setting is set to a Domain Name, a DNS request is initiated. Upon successful termination of the request, the FirewallHost setting is set to the corresponding address. If the search is not successful, an error is returned.

Note: This setting is provided for use by components that do not directly expose Firewall properties.

FirewallPassword: Password to be used if authentication is to be used when connecting through the firewall.

If FirewallHost is specified, the FirewallUser and FirewallPassword settings are used to connect and authenticate to the given firewall. If the authentication fails, the component raises an exception.

Note: This setting is provided for use by components that do not directly expose Firewall properties.

FirewallPort: The TCP port for the FirewallHost;.

The FirewallPort is set automatically when FirewallType is set to a valid value.

Note: This configuration setting is provided for use by components that do not directly expose Firewall properties.

FirewallType: Determines the type of firewall to connect through.

Possible values are as follows:


0	No firewall (default setting).
1	Connect through a tunneling proxy. FirewallPort is set to 80.
2	Connect through a SOCKS4 Proxy. FirewallPort is set to 1080.
3	Connect through a SOCKS5 Proxy. FirewallPort is set to 1080.
10	Connect through a SOCKS4A Proxy. FirewallPort is set to 1080.

Note: This setting is provided for use by components that do not directly expose Firewall properties.

FirewallUser: A user name if authentication is to be used connecting through a firewall.

If the FirewallHost is specified, the FirewallUser and FirewallPassword settings are used to connect and authenticate to the Firewall. If the authentication fails, the component raises an exception.

Note: This setting is provided for use by components that do not directly expose Firewall properties.

KeepAliveInterval: The retry interval, in milliseconds, to be used when a TCP keep-alive packet is sent and no response is received.

When set, TCPKeepAlive will automatically be set to True. A TCP keep-alive packet will be sent after a period of inactivity as defined by KeepAliveTime. If no acknowledgment is received from the remote host, the keep-alive packet will be sent again. This configuration setting specifies the interval at which the successive keep-alive packets are sent in milliseconds. This system default if this value is not specified here is 1 second.

Note: This value is not applicable in macOS.

KeepAliveTime: The inactivity time in milliseconds before a TCP keep-alive packet is sent.

When set, TCPKeepAlive will automatically be set to True. By default, the operating system will determine the time a connection is idle before a Transmission Control Protocol (TCP) keep-alive packet is sent. This system default if this value is not specified here is 2 hours. In many cases, a shorter interval is more useful. Set this value to the desired interval in milliseconds.

Linger: When set to True, connections are terminated gracefully.

This property controls how a connection is closed. The default is True.

In the case that Linger is True (default), two scenarios determine how long the connection will linger. In the first, if LingerTime is 0 (default), the system will attempt to send pending data for a connection until the default IP timeout expires.

In the second scenario, if LingerTime is a positive value, the system will attempt to send pending data until the specified LingerTime is reached. If this attempt fails, then the system will reset the connection.

The default behavior (which is also the default mode for stream sockets) might result in a long delay in closing the connection. Although the component returns control immediately, the system could hold system resources until all pending data are sent (even after your application closes).

Setting this property to False forces an immediate disconnection. If you know that the other side has received all the data you sent (e.g., by a client acknowledgment), setting this property to False might be the appropriate course of action.

LingerTime: Time in seconds to have the connection linger.

LingerTime is the time, in seconds, the socket connection will linger. This value is 0 by default, which means it will use the default IP timeout.

LocalHost: The name of the local host through which connections are initiated or accepted.

The LocalHost setting contains the name of the local host as obtained by the gethostname() system call, or if the user has assigned an IP address, the value of that address.

In multihomed hosts (machines with more than one IP interface), setting LocalHost to the value of an interface will make the component initiate connections (or accept in the case of server components) only through that interface.

If the component is connected, the LocalHost setting shows the IP address of the interface through which the connection is made in internet dotted format (aaa.bbb.ccc.ddd). In most cases, this is the address of the local host, except for multihomed hosts (machines with more than one IP interface).

LocalPort: The port in the local host where the component binds.

This configuration setting must be set before a connection is attempted. It instructs the component to bind to a specific port (or communication endpoint) in the local machine.

Setting this to 0 (default) enables the system to choose a port at random. The chosen port will be shown by LocalPort after the connection is established.

LocalPort cannot be changed once a connection is made. Any attempt to set this when a connection is active will generate an error.

This configuration setting is useful when trying to connect to services that require a trusted port on the client side. An example is the remote shell (rsh) service in UNIX systems.

MaxLineLength: The maximum amount of data to accumulate when no EOL is found.

MaxLineLength is the size of an internal buffer, which holds received data while waiting for an EOL string.

If an EOL string is found in the input stream before MaxLineLength bytes are received, the DataIn event is fired with the EOL parameter set to True, and the buffer is reset.

If no EOL is found, and MaxLineLength bytes are accumulated in the buffer, the DataIn event is fired with the EOL parameter set to False, and the buffer is reset.

The minimum value for MaxLineLength is 256 bytes. The default value is 2048 bytes.

MaxTransferRate: The transfer rate limit in bytes per second.

This configuration setting can be used to throttle outbound TCP traffic. Set this to the number of bytes to be sent per second. By default, this is not set and there is no limit.

ProxyExceptionsList: A semicolon separated list of hosts and IPs to bypass when using a proxy.

This configuration setting optionally specifies a semicolon-separated list of hostnames or IP addresses to bypass when a proxy is in use. When requests are made to hosts specified in this property, the proxy will not be used. For instance:

www.google.com;www.nsoftware.com

TCPKeepAlive: Determines whether or not the keep alive socket option is enabled.

If set to True, the socket's keep-alive option is enabled and keep-alive packets will be sent periodically to maintain the connection. Set KeepAliveTime and KeepAliveInterval to configure the timing of the keep-alive packets.

Note: This value is not applicable in Java.

TcpNoDelay: Whether or not to delay when sending packets.

When set to True, the socket will send all data that are ready to send at once. When set to False, the socket will send smaller buffered packets of data at small intervals. This is known as the Nagle algorithm.

By default, this configuration setting is set to False.

UseIPv6: Whether to use IPv6.

When set to 0 (default), the component will use IPv4 exclusively. When set to 1, the component will use IPv6 exclusively. To instruct the component to prefer IPv6 addresses, but use IPv4 if IPv6 is not supported on the system, this setting should be set to 2. The default value is 0. Possible values are as follows:


0	IPv4 only
1	IPv6 only
2	IPv6 with IPv4 fallback

SSL Config Settings

LogSSLPackets: Controls whether SSL packets are logged when using the internal security API.

When SSLProvider is set to Internal, this configuration setting controls whether Secure Sockets Layer (SSL) packets should be logged. By default, this configuration setting is False, as it is useful only for debugging purposes.

When enabled, SSL packet logs are output using the SSLStatus event, which will fire each time an SSL packet is sent or received.

Enabling this configuration setting has no effect if SSLProvider is set to Platform.

OpenSSLCADir: The path to a directory containing CA certificates.

This functionality is available only when the provider is OpenSSL.

The path set by this property should point to a directory containing CA certificates in PEM format. The files each contain one CA certificate. The files are looked up by the CA subject name hash value, which must hence be available. If more than one CA certificate with the same name hash value exist, the extension must be different (e.g., 9d66eef0.0, 9d66eef0.1). OpenSSL recommends the use of the c_rehash utility to create the necessary links. Please refer to the OpenSSL man page SSL_CTX_load_verify_locations(3) for details.

OpenSSLCAFile: Name of the file containing the list of CA's trusted by your application.

This functionality is available only when the provider is OpenSSL.

The file set by this property should contain a list of CA certificates in PEM format. The file can contain several CA certificates identified by the following sequences:

-----BEGIN CERTIFICATE-----

... (CA certificate in base64 encoding) ...

-----END CERTIFICATE-----

Before, between, and after the certificate text is allowed, which can be used, for example, for descriptions of the certificates. Refer to the OpenSSL man page SSL_CTX_load_verify_locations(3) for details.

OpenSSLCipherList: A string that controls the ciphers to be used by SSL.

This functionality is available only when the provider is OpenSSL.

The format of this string is described in the OpenSSL man page ciphers(1) section "CIPHER LIST FORMAT". Please refer to it for details. The default string "DEFAULT" is determined at compile time and is normally equivalent to "ALL:!ADH:RC4+RSA:+SSLv2:@STRENGTH".

OpenSSLPrngSeedData: The data to seed the pseudo random number generator (PRNG).

This functionality is available only when the provider is OpenSSL.

By default, OpenSSL uses the device file "/dev/urandom" to seed the PRNG, and setting OpenSSLPrngSeedData is not required. If set, the string specified is used to seed the PRNG.

ReuseSSLSession: Determines if the SSL session is reused.

If set to True, the component will reuse the context if and only if the following criteria are met:

The target host name is the same.
The system cache entry has not expired (default timeout is 10 hours).
The application process that calls the function is the same.
The logon session is the same.
The instance of the component is the same.

SSLCACerts: A newline separated list of CA certificates to be included when performing an SSL handshake.

When SSLProvider is set to Internal, this configuration setting specifies one or more CA certificates to be included with the SSLCert property. Some servers or clients require the entire chain, including CA certificates, to be presented when performing SSL authentication. The value of this configuration setting is a newline-separated (CR/LF) list of certificates. For instance:

-----BEGIN CERTIFICATE-----
MIIEKzCCAxOgAwIBAgIRANTET4LIkxdH6P+CFIiHvTowDQYJKoZIhvcNAQELBQAw
... Intermediate Cert ...
eWHV5OW1K53o/atv59sOiW5K3crjFhsBOd5Q+cJJnU+SWinPKtANXMht+EDvYY2w
F0I1XhM+pKj7FjDr+XNj
-----END CERTIFICATE-----
\r \n
-----BEGIN CERTIFICATE-----
MIIEFjCCAv6gAwIBAgIQetu1SMxpnENAnnOz1P+PtTANBgkqhkiG9w0BAQUFADBp
... Root Cert ...
d8q23djXZbVYiIfE9ebr4g3152BlVCHZ2GyPdjhIuLeH21VbT/dyEHHA
-----END CERTIFICATE-----

SSLCheckCRL: Whether to check the Certificate Revocation List for the server certificate.

This configuration setting specifies whether the component will check the Certificate Revocation List (CRL) specified by the server certificate. If set to 1 or 2, the component will first obtain the list of CRL URLs from the server certificate's CRL distribution points extension. The component will then make HTTP requests to each CRL endpoint to check the validity of the server's certificate. If the certificate has been revoked or any other issues are found during validation the component raises an exception.

When set to 0 (default), the CRL check will not be performed by the component. When set to 1, it will attempt to perform the CRL check, but it will continue without an error if the server's certificate does not support CRL. When set to 2, it will perform the CRL check and will throw an error if CRL is not supported.

This configuration setting is supported only in the Java, C#, and C++ editions. In the C++ edition, it is supported only on Windows operating systems.

SSLCheckOCSP: Whether to use OCSP to check the status of the server certificate.

This configuration setting specifies whether the component will use OCSP to check the validity of the server certificate. If set to 1 or 2, the component will first obtain the Online Certificate Status Protocol (OCSP) URL from the server certificate's OCSP extension. The component will then locate the issuing certificate and make an HTTP request to the OCSP endpoint to check the validity of the server's certificate. If the certificate has been revoked or any other issues are found during validation, the component raises an exception.

When set to 0 (default), the component will not perform an OCSP check. When set to 1, it will attempt to perform the OCSP check, but it will continue without an error if the server's certificate does not support OCSP. When set to 2, it will perform the OCSP check and will throw an error if OCSP is not supported.

This configuration setting is supported only in the Java, C#, and C++ editions. In the C++ edition, it is supported only on Windows operating systems.

SSLCipherStrength: The minimum cipher strength used for bulk encryption.

This minimum cipher strength is largely dependent on the security modules installed on the system. If the cipher strength specified is not supported, an error will be returned when connections are initiated.

Note: This configuration setting contains the minimum cipher strength requested from the security library. The actual cipher strength used for the connection is shown by the SSLStatus event.

Use this configuration setting with caution. Requesting a lower cipher strength than necessary could potentially cause serious security vulnerabilities in your application.

When the provider is OpenSSL, SSLCipherStrength is currently not supported. This functionality is instead made available through the OpenSSLCipherList configuration setting.

SSLClientCACerts: A newline separated list of CA certificates to use during SSL client certificate validation.

This configuration setting is only applicable to server components (e.g., TCPServer) see SSLServerCACerts for client components (e.g., TCPClient). This setting can be used to optionally specify one or more CA certificates to be used when verifying the client certificate that is presented by the client during the SSL handshake when SSLAuthenticateClients is enabled. When verifying the client's certificate, the certificates trusted by the system will be used as part of the verification process. If the client's CA certificates are not installed to the trusted system store, they may be specified here so they are included when performing the verification process. This configuration setting should be set only if the client's CA certificates are not already trusted on the system and cannot be installed to the trusted system store.

The value of this configuration setting is a newline-separated (CR/LF) list of certificates. For instance:

-----BEGIN CERTIFICATE-----
MIIEKzCCAxOgAwIBAgIRANTET4LIkxdH6P+CFIiHvTowDQYJKoZIhvcNAQELBQAw
... Intermediate Cert ...
eWHV5OW1K53o/atv59sOiW5K3crjFhsBOd5Q+cJJnU+SWinPKtANXMht+EDvYY2w
F0I1XhM+pKj7FjDr+XNj
-----END CERTIFICATE-----
\r \n
-----BEGIN CERTIFICATE-----
MIIEFjCCAv6gAwIBAgIQetu1SMxpnENAnnOz1P+PtTANBgkqhkiG9w0BAQUFADBp
... Root Cert ...
d8q23djXZbVYiIfE9ebr4g3152BlVCHZ2GyPdjhIuLeH21VbT/dyEHHA
-----END CERTIFICATE-----

SSLEnabledCipherSuites: The cipher suite to be used in an SSL negotiation.

This configuration setting enables the cipher suites to be used in SSL negotiation.

By default, the enabled cipher suites will include all available ciphers ("*").

The special value "*" means that the component will pick all of the supported cipher suites. If SSLEnabledCipherSuites is set to any other value, only the specified cipher suites will be considered.

Multiple cipher suites are separated by semicolons.

Example values when SSLProvider is set to Platform include the following:

  Copy
obj.config("SSLEnabledCipherSuites=*");
obj.config("SSLEnabledCipherSuites=CALG_AES_256");
obj.config("SSLEnabledCipherSuites=CALG_AES_256;CALG_3DES");

Possible values when SSLProvider is set to Platform include the following:

CALG_3DES
CALG_3DES_112
CALG_AES
CALG_AES_128
CALG_AES_192
CALG_AES_256
CALG_AGREEDKEY_ANY
CALG_CYLINK_MEK
CALG_DES
CALG_DESX
CALG_DH_EPHEM
CALG_DH_SF
CALG_DSS_SIGN
CALG_ECDH
CALG_ECDH_EPHEM
CALG_ECDSA
CALG_ECMQV
CALG_HASH_REPLACE_OWF
CALG_HUGHES_MD5
CALG_HMAC
CALG_KEA_KEYX
CALG_MAC
CALG_MD2
CALG_MD4
CALG_MD5
CALG_NO_SIGN
CALG_OID_INFO_CNG_ONLY
CALG_OID_INFO_PARAMETERS
CALG_PCT1_MASTER
CALG_RC2
CALG_RC4
CALG_RC5
CALG_RSA_KEYX
CALG_RSA_SIGN
CALG_SCHANNEL_ENC_KEY
CALG_SCHANNEL_MAC_KEY
CALG_SCHANNEL_MASTER_HASH
CALG_SEAL
CALG_SHA
CALG_SHA1
CALG_SHA_256
CALG_SHA_384
CALG_SHA_512
CALG_SKIPJACK
CALG_SSL2_MASTER
CALG_SSL3_MASTER
CALG_SSL3_SHAMD5
CALG_TEK
CALG_TLS1_MASTER
CALG_TLS1PRF

Example values when SSLProvider is set to Internalinclude the following:

  Copy
obj.config("SSLEnabledCipherSuites=*");
obj.config("SSLEnabledCipherSuites=TLS_DHE_DSS_WITH_AES_128_CBC_SHA");
obj.config("SSLEnabledCipherSuites=TLS_DHE_DSS_WITH_AES_128_CBC_SHA;TLS_ECDH_RSA_WITH_AES_128_CBC_SHA");

Possible values when SSLProvider is set to Internal include the following:

TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384
TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256
TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384
TLS_RSA_WITH_AES_256_GCM_SHA384
TLS_RSA_WITH_AES_128_GCM_SHA256
TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256
TLS_DHE_DSS_WITH_AES_256_GCM_SHA384
TLS_DHE_RSA_WITH_AES_256_GCM_SHA384
TLS_ECDH_RSA_WITH_AES_256_GCM_SHA384
TLS_ECDH_RSA_WITH_AES_128_GCM_SHA256
TLS_DHE_RSA_WITH_AES_128_GCM_SHA256
TLS_DHE_DSS_WITH_AES_128_GCM_SHA256
TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384
TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256
TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA384
TLS_DHE_DSS_WITH_AES_256_CBC_SHA256
TLS_RSA_WITH_AES_256_CBC_SHA256
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384
TLS_ECDH_RSA_WITH_AES_256_CBC_SHA384
TLS_DHE_RSA_WITH_AES_256_CBC_SHA256
TLS_DHE_RSA_WITH_AES_128_CBC_SHA256
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256
TLS_RSA_WITH_AES_128_CBC_SHA256
TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA256
TLS_ECDH_RSA_WITH_AES_128_CBC_SHA256
TLS_DHE_DSS_WITH_AES_128_CBC_SHA256
TLS_RSA_WITH_AES_256_CBC_SHA
TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA
TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA
TLS_DHE_RSA_WITH_AES_256_CBC_SHA
TLS_ECDH_RSA_WITH_AES_256_CBC_SHA
TLS_DHE_DSS_WITH_AES_256_CBC_SHA
TLS_RSA_WITH_AES_128_CBC_SHA
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA
TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA
TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA
TLS_ECDH_RSA_WITH_AES_128_CBC_SHA
TLS_DHE_RSA_WITH_AES_128_CBC_SHA
TLS_DHE_DSS_WITH_AES_128_CBC_SHA
TLS_ECDHE_ECDSA_WITH_3DES_EDE_CBC_SHA
TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA
TLS_ECDH_ECDSA_WITH_3DES_EDE_CBC_SHA
TLS_ECDH_RSA_WITH_3DES_EDE_CBC_SHA
TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA
TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA
TLS_RSA_WITH_3DES_EDE_CBC_SHA
TLS_RSA_WITH_DES_CBC_SHA
TLS_DHE_RSA_WITH_DES_CBC_SHA
TLS_DHE_DSS_WITH_DES_CBC_SHA
TLS_RSA_WITH_RC4_128_MD5
TLS_RSA_WITH_RC4_128_SHA

When TLS 1.3 is negotiated (see SSLEnabledProtocols), only the following cipher suites are supported:

TLS_AES_256_GCM_SHA384
TLS_CHACHA20_POLY1305_SHA256
TLS_AES_128_GCM_SHA256

SSLEnabledCipherSuites is used together with SSLCipherStrength.

SSLEnabledProtocols: Used to enable/disable the supported security protocols.

This configuration setting is used to enable or disable the supported security protocols.

Not all supported protocols are enabled by default. The default value is 4032 for client components, and 3072 for server components. To specify a combination of enabled protocol versions set this config to the binary OR of one or more of the following values:


TLS1.3	12288 (Hex 3000)
TLS1.2	3072 (Hex C00) (Default - Client and Server)
TLS1.1	768 (Hex 300) (Default - Client)
TLS1	192 (Hex C0) (Default - Client)
SSL3	48 (Hex 30)
SSL2	12 (Hex 0C)

Note that only TLS 1.2 is enabled for server components that accept incoming connections. This adheres to industry standards to ensure a secure connection. Client components enable TLS 1.0, TLS 1.1, and TLS 1.2 by default and will negotiate the highest mutually supported version when connecting to a server, which should be TLS 1.2 in most cases.

SSLEnabledProtocols: Transport Layer Security (TLS) 1.3 Notes:

By default when TLS 1.3 is enabled, the component will use the internal TLS implementation when the SSLProvider is set to Automatic for all editions.

In editions that are designed to run on Windows, SSLProvider can be set to Platform to use the platform implementation instead of the internal implementation. When configured in this manner, please note that the platform provider is supported only on Windows 11/Windows Server 2022 and up. The default internal provider is available on all platforms and is not restricted to any specific OS version.

If set to 1 (Platform provider), please be aware of the following notes:

The platform provider is available only on Windows 11/Windows Server 2022 and up.
SSLEnabledCipherSuites and other similar SSL configuration settings are not supported.
If SSLEnabledProtocols includes both TLS 1.3 and TLS 1.2, these restrictions are still applicable even if TLS 1.2 is negotiated. Enabling TLS 1.3 with the platform provider changes the implementation used for all TLS versions.

SSLEnabledProtocols: SSL2 and SSL3 Notes:

SSL 2.0 and 3.0 are not supported by the component when the SSLProvider is set to internal. To use SSL 2.0 or SSL 3.0, the platform security API must have the protocols enabled and SSLProvider needs to be set to platform.

SSLEnableRenegotiation: Whether the renegotiation_info SSL extension is supported.

This configuration setting specifies whether the renegotiation_info SSL extension will be used in the request when using the internal security API. This configuration setting is False by default, but it can be set to True to enable the extension.

This configuration setting is applicable only when SSLProvider is set to Internal.

SSLIncludeCertChain: Whether the entire certificate chain is included in the SSLServerAuthentication event.

This configuration setting specifies whether the Encoded parameter of the SSLServerAuthentication event contains the full certificate chain. By default this value is False and only the leaf certificate will be present in the Encoded parameter of the SSLServerAuthentication event.

If set to True, all certificates returned by the server will be present in the Encoded parameter of the SSLServerAuthentication event. This includes the leaf certificate, any intermediate certificate, and the root certificate.

SSLKeyLogFile: The location of a file where per-session secrets are written for debugging purposes.

This configuration setting optionally specifies the full path to a file on disk where per-session secrets are stored for debugging purposes.

When set, the component will save the session secrets in the same format as the SSLKEYLOGFILE environment variable functionality used by most major browsers and tools, such as Chrome, Firefox, and cURL. This file can then be used in tools such as Wireshark to decrypt TLS traffic for debugging purposes. When writing to this file, the component will only append, it will not overwrite previous values.

Note: This configuration setting is applicable only when SSLProvider is set to Internal.

SSLNegotiatedCipher: Returns the negotiated cipher suite.

This configuration setting returns the cipher suite negotiated during the SSL handshake.