mqtt5/doc/qbk/reference/properties/connect_props.qbk

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    Copyright (c) 2023 Mireo
   
    Distributed under the Boost Software License, Version 1.0. (See accompanying
    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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[section:async_mqtt5__connect_props CONNECT properties]
The last field in the Variable header of __CONNECT__ packet is a set of Properties.
A set contains a Property Length followed by the Properties.
A Property consists of an Identifier and a value.

This section lists all possible __CONNECT__ Properties and describes their usage:

[table:connect_props CONNECT properties
	[[Identifier] [Value type] [Description]]
	[[session_expiry_interval] [`int32_t`] [Represents the Session Expiry Internal in seconds.]]
	[[receive_maximum] [`int16_t`] [The maximum number of QoS 1 and QoS 2 publications that the Client is willing to process concurrently.]]
	[[maximum_packet_size] [`int32_t`] [The maximum __PACKET_SIZE__ in bytes as defined by the specification that the Client is willing to process.]]
	[[topic_alias_maximum] [`uint16_t`] [The highest value that the Client will accept as a Topic Alias sent by the Server.]]
	[[request_response_information] [`uint8_t`] [The value of 0 signals that the Server MUST NOT return Response Information in __CONNACK__. If the value if 1, it MAY return it.]]
	[[request_problem_information] [`uint8_t`] [The value of 0 signals that the Server MAY return a Reason String or User Properties on a __CONNACK__ or __DISCONNECT__ packet, 
		but MUST NOT send them on any packet other than __PUBLISH__, __CONNACK__, or __DISCONNECT__. 
		If the value is 1, the Server MAY return a Reason String or User Properties where it is allowed.]]
	[[user_property] [`std::vector<std::string>`] [A list of name, value pairs (__UTF8_STRING_PAIR__) defining User Properties. 
		The meaning of these properties is not defined by the specification.]]
	[[authentication_method] [`std::string`] [A UTF-8 Encoded String containing the name of the authentication method used for extended authentication.]]
	[[authentication_data] [`std::string`] [Binary Data containing authentication data. The contents of the data are defined by the authentication method.]]
]

[h4 Usage]
After obtaining an instance of `async_mqtt5::connect_props`, the subscript operator can be used to access a Property.

The Identifiers listed in the table above are available within the `async_mqtt5::prop` namespace for Property access.

[h4 Example]

[!c++]
	async_mqtt5::connect_props props;
	props[async_mqtt5::prop::session_expiry_interval] = 1200;
	props[async_mqtt5::prop::receive_maximum] = int16_t(100);

[endsect]