forked from boostorg/mqtt5
Korina Šimičević
40ad372736
Summary: related to T15996 updates copyright year to 2025 Reviewers: ivica Reviewed By: ivica Subscribers: iljazovic, miljen Differential Revision: https://repo.mireo.local/D33759
56 lines
2.6 KiB
Plaintext
56 lines
2.6 KiB
Plaintext
[/
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Copyright (c) 2023-2025 Ivica Siladic, Bruno Iljazovic, Korina Simicevic
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Distributed under the Boost Software License, Version 1.0.
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(See accompanying file LICENSE or copy at http://www.boost.org/LICENSE_1_0.txt)
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[section:disconnect_props DISCONNECT properties]
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The last field in the Variable header of __DISCONNECT__ packet is a set of Properties.
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A set contains a Property Length followed by the Properties.
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A Property consists of an Identifier and a value.
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This section lists all possible __DISCONNECT__ Properties and describes their usage:
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[table:disconnect_props DISCONNECT properties
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[[Identifier] [Value type] [Description]]
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[[session_expiry_interval] [`uint32_t`] [Represents the Session Expiry Internal in seconds. Can only be sent by the Client.]]
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[[reason_string] [`std::string`] [A UTF-8 Encoded String representing the reason associated with this response.]]
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[[user_property] [`std::pair<std::string, std::string>`] [Name, value pair (__UTF8_STRING_PAIR__) defining User Property. There can be multiple pairs in one packet.
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This property may be used to provide additional diagnostic or other information. ]]
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[[server_reference] [`std::string`] [A UTF-8 Encoded String which can be used by the Client to identfy another Server to use.]]
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]
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[h4 Usage]
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After obtaining an instance of `boost::mqtt5::disconnect_props`, the subscript operator can be used to access a Property.
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The Identifiers listed in the table above are available within the `boost::mqtt5::prop` namespace for Property access.
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[note When accessing a property value, the subscript operator will return a `std::optional` of the value type for all properties,
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except for `boost::mqtt5::prop::user_property`, where it will return an instance of `std::vector<std::pair<std::string, std::string>>`.]
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[h4 Example]
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The following example shows how to set a Property value:
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[!c++]
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boost::mqtt5::disconnect_props props;
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props[boost::mqtt5::prop::reason_string] = "Lost connection!";
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props[boost::mqtt5::prop::user_property].emplace_back("name", "value");
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The following example shows how to retrieve a Property value:
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[!c++]
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std::optional<std::string> reason_string = props[boost::mqtt5::prop::reason_string];
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if (reason_string.has_value())
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// reason string property was previously set
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else
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// reason string property was not set
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std::vector<std::pair<std::string, std::string>>& user_props = props[boost::mqtt5::prop::user_property];
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if (!user_props.empty())
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// user property was previously set
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else
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// user property was not set
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[endsect]
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