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mqtt5/include/async_mqtt5/mqtt_client.hpp
Bruno Iljazovic 4f87b27861 async_run
Reviewers: ivica

Reviewed By: ivica

Subscribers: korina

Differential Revision: https://repo.mireo.local/D27342
2024-01-16 13:18:21 +01:00

859 lines
31 KiB
C++

#ifndef ASYNC_MQTT5_MQTT_CLIENT_HPP
#define ASYNC_MQTT5_MQTT_CLIENT_HPP
#include <boost/system/error_code.hpp>
#include <async_mqtt5/error.hpp>
#include <async_mqtt5/types.hpp>
#include <async_mqtt5/impl/client_service.hpp>
#include <async_mqtt5/impl/publish_send_op.hpp>
#include <async_mqtt5/impl/read_message_op.hpp>
#include <async_mqtt5/impl/subscribe_op.hpp>
#include <async_mqtt5/impl/unsubscribe_op.hpp>
#include <async_mqtt5/impl/re_auth_op.hpp>
namespace async_mqtt5 {
namespace asio = boost::asio;
/**
* \brief \__MQTT\__ client used to connect and communicate with a Broker.
*
* \tparam \__StreamType\__ Type of the underlying transport protocol used to transfer
* the stream of bytes between the Client and the Broker. The transport must be
* ordered and lossless.
* \tparam \__TlsContext\__ Type of the context object used in TLS/SSL connections.
*
* \par Thread safety
* ['Distinct objects]: safe. \n
* ['Shared objects]: unsafe. \n
* This class is [*not thread-safe].
* The application must also ensure that all asynchronous operations are performed within the same implicit or explicit strand.
*/
template <
typename StreamType,
typename TlsContext = std::monostate
>
class mqtt_client {
public:
/// The executor type associated with the client.
using executor_type = typename StreamType::executor_type;
private:
using stream_type = StreamType;
using tls_context_type = TlsContext;
static constexpr auto read_timeout = std::chrono::seconds(5);
using client_service_type = detail::client_service<
stream_type, tls_context_type
>;
using clisvc_ptr = std::shared_ptr<client_service_type>;
clisvc_ptr _svc_ptr;
public:
/**
* \brief Constructs a Client with given parameters.
*
* \param ex An executor that will be associated with the Client.
* \param cnf
* \param tls_context A context object used in TLS/SLL connection.
*/
explicit mqtt_client(
const executor_type& ex,
const std::string& cnf,
TlsContext tls_context = {}
) :
_svc_ptr(std::make_shared<client_service_type>(
ex, cnf, std::move(tls_context)
))
{}
/**
* \brief Constructs a Client with given parameters.
*
* \tparam \__ExecutionContext\__ Type of a concrete execution context.
* \param context Execution context whose executor will be associated with the Client.
* \param cnf
* \param tls_context A context object used in TLS/SLL connection.
*
* \par Precondition
* \code
* std::is_convertible_v<ExecutionContext&, asio::execution_context&>
* \endcode
*/
template <
typename ExecutionContext,
std::enable_if_t<
std::is_convertible_v<ExecutionContext&, asio::execution_context&>,
bool
> = true
>
explicit mqtt_client(
ExecutionContext& context,
const std::string& cnf,
TlsContext tls_context = {}
) :
mqtt_client(context.get_executor(), cnf, std::move(tls_context))
{}
/**
* \brief Move-construct an mqtt_client from another.
*
* \details Moved-from client can only be destructed
*/
mqtt_client(mqtt_client&& other) noexcept = default;
/**
* \brief Move assignment operator.
*
* \details Cancels this client first. Moved-from client can only be destructed.
*/
mqtt_client& operator=(mqtt_client&& other) noexcept {
cancel();
_svc_ptr = std::move(other._svc_ptr);
return *this;
}
/**
* \brief Destructor.
*
* \details Automatically calls \ref mqtt_client::cancel.
*/
~mqtt_client() {
if (_svc_ptr) cancel();
}
/**
* \brief Get the executor associated with the object.
*/
executor_type get_executor() const noexcept {
return _svc_ptr->get_executor();
}
/**
* \brief Get the context object used in TLS/SSL connection.
*
* \note This function may only be invoked
* when the template parameter \__TlsContext\__ was configured
* with non-default type during the creation of a \ref mqtt_client.
*
* \par Precondition
* \code
* !std::is_same_v<TlsContext, std::monostate>
* \endcode
*/
template <
typename Ctx = TlsContext,
std::enable_if_t<!std::is_same_v<Ctx, std::monostate>, bool> = true
>
decltype(auto) tls_context()
{
return _svc_ptr->tls_context();
}
/**
* \brief Start the Client.
*
* \param token Completion token that will be used to produce a
* completion handler. The handler will be invoked when the operation completes.
*
* \par Handler signature
* The handler signature for this operation:
* \code
* void (__ERROR_CODE__)
* \endcode
*
* \par Completion condition
* The asynchronous operation will complete with
* `boost::asio::error::operation_aborted` when client is cancelled by calling
* \ref mqtt_client::async_disconnect, \ref mqtt_client::cancel, destruction or
* if non-recoverable error happens during connection attempt (e.g. access denied).
*
* \par Error codes
* The list of all possible error codes that this operation can finish with:\n
* - `boost::asio::error::operation_aborted`\n
*/
template <typename CompletionToken>
decltype(auto) async_run(CompletionToken&& token) {
using Signature = void(error_code);
auto initiation = [] (auto handler, const clisvc_ptr& svc_ptr) {
svc_ptr->run(std::move(handler));
detail::ping_op { svc_ptr }
.perform(read_timeout - std::chrono::seconds(1));
detail::read_message_op { svc_ptr }.perform();
detail::sentry_op { svc_ptr }.perform();
};
return asio::async_initiate<CompletionToken, Signature>(
initiation, token, _svc_ptr
);
}
/**
* \brief Cancel all asynchronous operations. This function has terminal effects.
*
* \details All outstanding operations will complete
* with `boost::asio::error::operation_aborted`.
*
* \attention This function has terminal effects and will close the Client.
* The Client cannot be used before calling \ref mqtt_client::async_run again.
*/
void cancel() {
_svc_ptr->cancel();
}
/**
* \brief Assign a \ref will Message.
*
* \details The \ref will Message that the Broker should publish
* after the Network Connection is closed and it is not
* closed normally.
*
* \attention This function takes action when the client is in a non-operational state,
* meaning the \ref async_run function has not been invoked.
* Furthermore, you can use this function after the \ref cancel function has been called,
* before the \ref async_run function is invoked again.
*/
mqtt_client& will(will will) {
_svc_ptr->will(std::move(will));
return *this;
}
/**
* \brief Assign credentials that will be used to connect to a Broker.
*
* \details Credentials consist of a unique Client Identifier and, optionally,
* a User Name and Password.
*
* \attention This function takes action when the client is in a non-operational state,
* meaning the \ref async_run function has not been invoked.
* Furthermore, you can use this function after the \ref cancel function has been called,
* before the \ref async_run function is invoked again.
*/
mqtt_client& credentials(
std::string client_id,
std::string username = "", std::string password = ""
) {
_svc_ptr->credentials(
std::move(client_id),
std::move(username), std::move(password)
);
return *this;
}
/**
* \brief Assign a list of Brokers that the Client will attempt to connect to.
*
* \details The Client will cycle through the list of hosts,
* attempting to establish a connection with each
* until it successfully establishes a connection.
*
* \param hosts List of Broker addresses and ports.
* Address and ports are separated with a colon `:` while
* pairs of addresses and ports are separated with a comma `,`.
* \param default_port The default port to connect to in case the port is not
* explicitly specified in the `hosts` list.
*
* \attention This function takes action when the client is in a non-operational state,
* meaning the \ref async_run function has not been invoked.
* Furthermore, you can use this function after the \ref cancel function has been called,
* before the \ref async_run function is invoked again.
*
* \par Example
* Some valid `hosts` string:
*
* \code
* std::string valid_hosts_1 = "broker1:1883, broker2, broker3:1883";
* std::string valid_hosts_2 = "broker1";
* \endcode
*
*/
mqtt_client& brokers(std::string hosts, uint16_t default_port = 1883) {
_svc_ptr->brokers(std::move(hosts), default_port);
return *this;
}
/**
* \brief Assign an authenticator that the Client will use for
* \__ENHANCED_AUTH\__ on every connect to a Broker.
* Re-authentication can be initiated by calling \ref re_authenticate.
*
* \param authenticator Object that will be stored (move-constructed or by reference)
* and used for authentication. It needs to satisfy \__is_authenticator\__ concept.
*
* \attention This function takes action when the client is in a non-operational state,
* meaning the \ref async_run function has not been invoked.
* Furthermore, you can use this function after the \ref cancel function has been called,
* before the \ref async_run function is invoked again.
*
*/
template <
typename Authenticator,
std::enable_if_t<detail::is_authenticator<Authenticator>, bool> = true
>
mqtt_client& authenticator(Authenticator&& authenticator) {
_svc_ptr->authenticator(std::forward<Authenticator>(authenticator));
return *this;
}
/**
* \brief Assign \__CONNECT_PROPS\__ that will be sent in a \__CONNECT\__ packet.
* \param props \__CONNECT_PROPS\__ sent in a \__CONNECT\__ packet.
* \see See \__CONNECT_PROPS\__ for all eligible properties.
*/
mqtt_client& connect_properties(connect_props props) {
_svc_ptr->connect_properties(std::move(props));
return *this;
}
/**
* \brief Assign a property that will be sent in a \__CONNECT\__ packet.
* \param prop The \__CONNECT_PROPS\__ property to set.
* \param value Value that will be assigned to the property.
*
* \par Example
* \code
* client.connect_property(prop::session_expiry_interval, 40); // ok
* client.connect_property(prop::reason_string, "reason"); // does not compile, not a CONNECT prop!
* \endcode
*
* \see See \__CONNECT_PROPS\__ for all eligible properties.
*/
template <prop::property_type p>
mqtt_client& connect_property(
std::integral_constant<prop::property_type, p> prop,
prop::value_type_t<p> value
) {
_svc_ptr->connect_property(prop) = value;
return *this;
}
/**
* \brief Initiates [mqttlink 3901257 Re-authentication]
* using the authenticator given in the \ref authenticator method.
*
* \note If \ref authenticator was not called, this method does nothing.
*/
void re_authenticate() {
detail::re_auth_op { _svc_ptr }.perform();
}
/**
* \brief Retrieves the value of a specific property from the last \__CONNACK\__ packet received.
*
* \details The return type varies according to the property requested.
* For all properties, the return type will be `std::optional` of their respective value type.
* For `async_mqtt5::prop::user_property`, the return type is `std::vector<std::string>`.
*
* \param prop The \__CONNACK_PROPS\__ property value to retrieve.
*
* \par Example
* \code
* std::optional<std::string> auth_method = client.connack_property(async_mqtt5::prop::authentication_method); // ok
* std::optional<std::string> c_type = client.connack_property(async_mqtt5::prop::content_type); // does not compile, not a CONNAK prop!
* \endcode
*
* \see See \__CONNACK_PROPS\__ for all eligible properties.
*/
template <prop::property_type p>
const auto& connack_property(
std::integral_constant<prop::property_type, p> prop
) const {
return _svc_ptr->connack_property(prop);
}
/**
* \brief Retrieves the \__CONNACK_PROPS\__ from the last \__CONNACK\__ packet received.
*
* \see See \__CONNACK_PROPS\__ for all eligible properties.
*/
const connack_props& connack_properties() const {
return _svc_ptr->connack_properties();
}
/**
* \brief Send a \__PUBLISH\__ packet to Broker to transport an
* Application Message.
*
* \tparam qos_type The \ref qos_e level of assurance for delivery.
* \param topic Identification of the information channel to which
* Payload data is published.
* \param payload The Application Message that is being published.
* \param retain The \ref retain_e flag.
* \param props An instance of \__PUBLISH_PROPS\__.
* \param token Completion token that will be used to produce a
* completion handler. The handler will be invoked when the operation completes.
* On immediate completion, invocation of the handler will be performed in a manner
* equivalent to using \__POST\__.
*
* \par Handler signature
* The handler signature for this operation depends on the \ref qos_e specified:\n
*
* `qos` == `qos_e::at_most_once`:
* \code
* void (
* __ERROR_CODE__ // Result of operation
* )
* \endcode
*
* `qos` == `qos_e::at_least_once`:
* \code
* void (
* __ERROR_CODE__, // Result of operation.
* __REASON_CODE__, // Reason Code received from Broker.
* __PUBACK_PROPS__ // Properties received in the PUBACK packet.
* )
* \endcode
*
* `qos` == `qos_e::exactly_once`:
* \code
* void (
* __ERROR_CODE__, // Result of operation.
* __REASON_CODE__, // Reason Code received from Broker.
* __PUBCOMP_PROPS__ // Properties received in the PUBCOMP packet.
* )
* \endcode
*
* \par Completion condition
* Depending on the \ref qos_e specified, the asynchronous operation will complete
* when one of the following conditions is true:\n
* - If `qos` == `qos_e::at_most_once` and the Client
* has successfully written the packet to the transport. \n
* - If `qos` == `qos_e::at_least_once` and the packet has
* been sent and acknowledged through the reception of a \__PUBACK\__ packet.
* - If `qos` == `qos_e::exactly_once` and the packet has
* been sent and fully acknowledged through the reception of a \__PUBCOMP\__ packet.
* - An error occurred. This is indicated by an associated \__ERROR_CODE\__ in the handler.\n
*
* \par Error codes
* The list of all possible error codes that this operation can finish with:\n
* - `boost::system::errc::errc_t::success` \n
* - `boost::asio::error::operation_aborted` \n
* - `boost::asio::error::no_recovery` \n
* - \link async_mqtt5::client::error::malformed_packet \endlink
* - \link async_mqtt5::client::error::packet_too_large \endlink
* - \link async_mqtt5::client::error::pid_overrun \endlink
* - \link async_mqtt5::client::error::qos_not_supported \endlink
* - \link async_mqtt5::client::error::retain_not_available \endlink
* - \link async_mqtt5::client::error::topic_alias_maximum_reached \endlink
* - \link async_mqtt5::client::error::invalid_topic \endlink
*
* Refer to the section on \__ERROR_HANDLING\__ to find the underlying causes for each error code.
*/
template <qos_e qos_type, typename CompletionToken>
decltype(auto) async_publish(
std::string topic, std::string payload,
retain_e retain, const publish_props& props,
CompletionToken&& token
) {
using Signature = detail::on_publish_signature<qos_type>;
auto initiation = [] (
auto handler, std::string topic, std::string payload,
retain_e retain, const publish_props& props,
const clisvc_ptr& svc_ptr
) {
detail::publish_send_op<
client_service_type, decltype(handler), qos_type
> { svc_ptr, std::move(handler) }
.perform(
std::move(topic), std::move(payload),
retain, props
);
};
return asio::async_initiate<CompletionToken, Signature>(
initiation, token,
std::move(topic), std::move(payload), retain, props, _svc_ptr
);
}
/**
* \brief Send a \__SUBSCRIBE\__ packet to Broker to create a subscription
* to one or more Topics of interest.
*
* \details After the subscription has been established, the Broker will send
* PUBLISH packets to the Client to forward Application Messages that were published
* to Topics that the Client subscribed to. The Application Messages can be received
* with \ref mqtt_client::async_receive function.
*
* \param topics A list of \ref subscribe_topic of interest.
* \param props An instance of \__SUBSCRIBE_PROPS\__.
* \param token Completion token that will be used to produce a
* completion handler. The handler will be invoked when the operation completes.
* On immediate completion, invocation of the handler will be performed in a manner
* equivalent to using \__POST\__.
*
* \par Handler signature
* The handler signature for this operation:
* \code
* void (
* __ERROR_CODE__, // Result of operation.
* std::vector<__REASON_CODE__>, // Vector of Reason Codes indicating
* // the subscription result for each Topic
* // in the SUBSCRIBE packet.
* __SUBACK_PROPS__, // Properties received in the SUBACK packet.
* )
* \endcode
*
* \par Completion condition
* The asynchronous operation will complete when one of the following conditions is true:\n
* - The Client has successfully sent a \__SUBSCRIBE\__ packet
* and has received a \__SUBACK\__ response from the Broker.\n
* - An error occurred. This is indicated by an associated \__ERROR_CODE\__ in the handler.\n
*
* \par Error codes
* The list of all possible error codes that this operation can finish with:\n
* - `boost::system::errc::errc_t::success` \n
* - `boost::asio::error::no_recovery` \n
* - `boost::asio::error::operation_aborted` \n
* - \link async_mqtt5::client::error::malformed_packet \endlink
* - \link async_mqtt5::client::error::packet_too_large \endlink
* - \link async_mqtt5::client::error::pid_overrun \endlink
* - \link async_mqtt5::client::error::invalid_topic \endlink
* - \link async_mqtt5::client::error::wildcard_subscription_not_available \endlink
* - \link async_mqtt5::client::error::subscription_identifier_not_available \endlink
* - \link async_mqtt5::client::error::shared_subscription_not_available \endlink
*
* Refer to the section on \__ERROR_HANDLING\__ to find the underlying causes for each error code.
*/
template <typename CompletionToken>
decltype(auto) async_subscribe(
const std::vector<subscribe_topic>& topics,
const subscribe_props& props,
CompletionToken&& token
) {
using Signature = void (
error_code, std::vector<reason_code>, suback_props
);
auto initiation = [] (
auto handler, const std::vector<subscribe_topic>& topics,
const subscribe_props& props, const clisvc_ptr& impl
) {
detail::subscribe_op { impl, std::move(handler) }
.perform(topics, props);
};
return asio::async_initiate<CompletionToken, Signature>(
initiation, token, topics, props, _svc_ptr
);
}
/**
* \brief Send a \__SUBSCRIBE\__ packet to Broker to create a subscription
* to one Topics of interest.
*
* \details After the subscription has been established, the Broker will send
* \__PUBLISH\__ packets to the Client to forward Application Messages that were published
* to Topics that the Client subscribed to. The Application Messages can be received
* with \ref mqtt_client::async_receive function.
*
* \param topic A \ref subscribe_topic of interest.
* \param props An instance of \__SUBSCRIBE_PROPS\__.
* \param token Completion token that will be used to produce a
* completion handler. The handler will be invoked when the operation completes.
* On immediate completion, invocation of the handler will be performed in a manner
* equivalent to using \__POST\__.
*
* \par Handler signature
* The handler signature for this operation:
* \code
* void (
* __ERROR_CODE__, // Result of operation.
* std::vector<__REASON_CODE__>, // Vector of Reason Codes containing the
* // single subscription result for the Topic
* // in the SUBSCRIBE packet.
* __SUBACK_PROPS__, // Properties received in the SUBACK packet.
* )
* \endcode
*
* \par Completion condition
* The asynchronous operation will complete when one of the following conditions is true:\n
* - The Client has successfully sent a \__SUBSCRIBE\__ packet
* and has received a \__SUBACK\__ response from the Broker.\n
* - An error occurred. This is indicated by an associated \__ERROR_CODE\__ in the handler.\n
*
* \par Error codes
* The list of all possible error codes that this operation can finish with:\n
* - `boost::system::errc::errc_t::success` \n
* - `boost::asio::error::no_recovery` \n
* - `boost::asio::error::operation_aborted` \n
* - \link async_mqtt5::client::error::malformed_packet \endlink
* - \link async_mqtt5::client::error::packet_too_large \endlink
* - \link async_mqtt5::client::error::pid_overrun \endlink
* - \link async_mqtt5::client::error::invalid_topic \endlink
* - \link async_mqtt5::client::error::wildcard_subscription_not_available \endlink
* - \link async_mqtt5::client::error::subscription_identifier_not_available \endlink
* - \link async_mqtt5::client::error::shared_subscription_not_available \endlink
*
* Refer to the section on \__ERROR_HANDLING\__ to find the underlying causes for each error code.
*/
template <typename CompletionToken>
decltype(auto) async_subscribe(
const subscribe_topic& topic, const subscribe_props& props,
CompletionToken&& token
) {
return async_subscribe(
std::vector<subscribe_topic> { topic }, props,
std::forward<CompletionToken>(token)
);
}
/**
* \brief Send an \__UNSUBSCRIBE\__ packet to Broker to unsubscribe from one
* or more Topics.
*
* \note The Client may still receive residual Application Messages
* through the \ref mqtt_client::async_receive function
* from Topics the Client just unsubscribed to.
*
* \param topics List of Topics to unsubscribe from.
* \param props An instance of \__UNSUBSCRIBE_PROPS\__.
* \param token Completion token that will be used to produce a
* completion handler. The handler will be invoked when the operation completes.
* On immediate completion, invocation of the handler will be performed in a manner
* equivalent to using \__POST\__.
*
* \par Handler signature
* The handler signature for this operation:
* \code
* void (
* __ERROR_CODE__, // Result of operation.
* std::vector<__REASON_CODE__>, // Vector of Reason Codes indicating
* // the result of unsubscribe operation
* // for each Topic in the UNSUBSCRIBE packet.
* __UNSUBACK_PROPS__, // Properties received in the UNSUBACK packet.
* )
* \endcode
*
* \par Completion condition
* The asynchronous operation will complete when one of the following conditions is true:\n
* - The Client has successfully sent an \__UNSUBSCRIBE\__ packet
* and has received an \__UNSUBACK\__ response from the Broker.\n
* - An error occurred. This is indicated by an associated \__ERROR_CODE\__ in the handler.\n
*
* \par Error codes
* The list of all possible error codes that this operation can finish with:\n
* - `boost::system::errc::errc_t::success` \n
* - `boost::asio::error::no_recovery` \n
* - `boost::asio::error::operation_aborted` \n
* - \link async_mqtt5::client::error::malformed_packet \endlink
* - \link async_mqtt5::client::error::packet_too_large \endlink
* - \link async_mqtt5::client::error::pid_overrun \endlink
* - \link async_mqtt5::client::error::invalid_topic \endlink
*
* Refer to the section on \__ERROR_HANDLING\__ to find the underlying causes for each error code.
*/
template <typename CompletionToken>
decltype(auto) async_unsubscribe(
const std::vector<std::string>& topics, const unsubscribe_props& props,
CompletionToken&& token
) {
using Signature = void (
error_code, std::vector<reason_code>, unsuback_props
);
auto initiation = [](
auto handler,
const std::vector<std::string>& topics,
const unsubscribe_props& props, const clisvc_ptr& impl
) {
detail::unsubscribe_op { impl, std::move(handler) }
.perform(topics, props);
};
return asio::async_initiate<CompletionToken, Signature>(
initiation, token, topics, props, _svc_ptr
);
}
/**
* \brief Send an \__UNSUBSCRIBE\__ packet to Broker to unsubscribe
* from one Topic.
*
* \note The Client may still receive residual Application Messages
* through the \ref mqtt_client::async_receive function
* from Topics the Client just unsubscribed to.
*
* \param topic Topic to unsubscribe from.
* \param props An instance of \__UNSUBSCRIBE_PROPS\__.
* \param token Completion token that will be used to produce a
* completion handler. The handler will be invoked when the operation completes.
* On immediate completion, invocation of the handler will be performed in a manner
* equivalent to using \__POST\__.
*
* \par Handler signature
* The handler signature for this operation:
* \code
* void (
* __ERROR_CODE__, // Result of operation.
* std::vector<__REASON_CODE__>, // Vector of Reason Codes containing
* // the result of unsubscribe operation
* // for the Topic in the UNSUBSCRIBE packet.
* __UNSUBACK_PROPS__, // Properties received in the UNSUBACK packet.
* )
* \endcode
*
* \par Completion condition
* The asynchronous operation will complete when one of the following conditions is true:\n
* - The Client has successfully sent an \__UNSUBSCRIBE\__ packet
* and has received an \__UNSUBACK\__ response from the Broker.\n
* - An error occurred. This is indicated by an associated \__ERROR_CODE\__ in the handler.\n
*
* \par Error codes
* The list of all possible error codes that this operation can finish with:\n
* - `boost::system::errc::errc_t::success` \n
* - `boost::asio::error::no_recovery` \n
* - `boost::asio::error::operation_aborted` \n
* - \link async_mqtt5::client::error::malformed_packet \endlink
* - \link async_mqtt5::client::error::packet_too_large \endlink
* - \link async_mqtt5::client::error::pid_overrun \endlink
* - \link async_mqtt5::client::error::invalid_topic \endlink
*
* Refer to the section on \__ERROR_HANDLING\__ to find the underlying causes for each error code.
*/
template <typename CompletionToken>
decltype(auto) async_unsubscribe(
const std::string& topic, const unsubscribe_props& props,
CompletionToken&& token
) {
return async_unsubscribe(
std::vector<std::string> { topic }, props,
std::forward<CompletionToken>(token)
);
}
/**
* \brief Asynchronously receive an Application Message.
*
* \details The Client will receive and complete deliveries for all the
* \__PUBLISH\__ packets received from the Broker throughout its lifetime.
* The Client will store them internally in order they were delivered.
* Calling this function will attempt to receive an Application Message
* from internal storage.
*
* \note It is only recommended to call this function if you have established
* a successful subscription to a Topic using the \ref async_subscribe function.
*
* \param token Completion token that will be used to produce a
* completion handler. The handler will be invoked when the operation completes.
* On immediate completion, invocation of the handler will be performed in a manner
* equivalent to using \__POST\__.
*
* \par Handler signature
* The handler signature for this operation:
* \code
* void (
* __ERROR_CODE__, // Result of operation.
* std::string, // Topic, the origin of the Application Message.
* std::string, // Payload, the content of the Application Message.
* __PUBLISH_PROPS__, // Properties received in the PUBLISH packet.
* )
* \endcode
*
* \par Completion condition
* The asynchronous operation will complete when one of the following conditions is true:\n
* - The Client has a pending Application Message in its internal storage
* ready to be received.
* - An error occurred. This is indicated by an associated \__ERROR_CODE\__ in the handler.\n
*
* \par Error codes
* The list of all possible error codes that this operation can finish with:\n
* - `boost::system::errc::errc_t::success`\n
* - `boost::asio::error::operation_aborted`\n
* - \link async_mqtt5::client::error::session_expired \endlink
*
* Refer to the section on \__ERROR_HANDLING\__ to find the underlying causes for each error code.
*/
template <typename CompletionToken>
decltype(auto) async_receive(CompletionToken&& token) {
// Sig = void (error_code, std::string, std::string, publish_props)
return _svc_ptr->async_channel_receive(
std::forward<CompletionToken>(token)
);
}
/**
* \brief Disconnect the Client by sending a \__DISCONNECT\__ packet
* with a specified Reason Code. This function has terminal effects.
*
* \details Send a \__DISCONNECT\__ packet to the Broker with a Reason Code
* describing the reason for disconnection.
*
* \attention This function has terminal effects and will close the Client.
* See \ref mqtt_client::cancel.
*
* \note If you wish to close the Client regardless of its state,
* prefer calling the \ref cancel function instead. This function will only
* take effect when the connection has been successfully established.
*
* \param reason_code Reason Code to notify
* the Broker of the reason for disconnection.
* \param props An instance of \__DISCONNECT_PROPS\__.
* \param token Completion token that will be used to produce a
* completion handler. The handler will be invoked when the operation completes.
* On immediate completion, invocation of the handler will be performed in a manner
* equivalent to using \__POST\__.
*
* \par Handler signature
* The handler signature for this operation:
* \code
* void (
* __ERROR_CODE__ // Result of operation.
* )
* \endcode
*
* \par Completion condition
* The asynchronous operation will complete when one of the following conditions is true:\n
* - The Client has attempted to send a \__DISCONNECT\__ packet, regardless of whether
* the sending was successful or not.\n
* - An error occurred. This is indicated by an associated \__ERROR_CODE\__ in the handler.\n
*
* \par Error codes
* The list of all possible error codes that this operation can finish with:\n
* - `boost::system::errc::errc_t::success`\n
* - `boost::asio::error::operation_aborted`\n
* - \link async_mqtt5::client::error::malformed_packet \endlink
*
* Refer to the section on \__ERROR_HANDLING\__ to find the underlying causes for each error code.
*/
template <typename CompletionToken>
decltype(auto) async_disconnect(
disconnect_rc_e reason_code, const disconnect_props& props,
CompletionToken&& token
) {
return detail::async_disconnect(
detail::disconnect_rc_e(static_cast<uint8_t>(reason_code)),
props, true, _svc_ptr,
std::forward<CompletionToken>(token)
);
}
/**
* \brief Disconnect the Client by sending a \__DISCONNECT\__ packet
* with a Reason Code of reason_codes.normal_disconnection.
* This function has terminal effects.
* \copydetails async_disconnect
*/
template <typename CompletionToken>
decltype(auto) async_disconnect(CompletionToken&& token) {
return async_disconnect(
disconnect_rc_e::normal_disconnection,
disconnect_props {}, std::forward<CompletionToken>(token)
);
}
};
} // end namespace async_mqtt5
#endif // !ASYNC_MQTT5_MQTT_CLIENT_HPP