Version 1.4.1

One bug fix.

• #458 Set 'disconnected' handler for the consumer queue.

Version 1.4.0

Reorganization of the sources and fixes for a number of CMake build issues, particularly to get the Paho C submodule build working with the existing C library, fixes for transient dependencies, and getting the Windows DLL (maybe, finally) working properly.

• Ability to build the Paho C library automatically (now working properly)

  • CMake 'PAHO_WITH_MQTT_C' option properly compiles the existing Paho C v1.3.13
  • Moved 'src/externals/' to top-level

• Reorganized the source tree:

  • Moved header files to top-level 'include/' directory.
  • Moved 'src/sampless/' to top-level and renamed 'examples/'

• Fixed and optimized 'topic_matcher' trie collection

• Added some missing Eclipse/Paho legal documents to the repo.

• Ran a spell-checker over the code and doc files.

• #498 Overloaded property constructor to also take a uint32_t

• #491 add topic_matcher.h to install

• #485 export dependencies

• #484 add token::get_message

• #480 Fixed Paho C version in 'install_paho_mqtt_c.sh' script.

• #473 Getter for the client's cached connect options.

• #466 Iterable string collection

• #416 Removed FindPahoMqttC.cmake. Using Paho C package directly.

Version 1.3.2

Minor bug fixes.

• #463 Fixed generator expression for older CMake
• #378 Bad LWT message in async_publish.cpp sample.

Version 1.3.1

Patch for improper Version constants in 1.3.0 source.

• #462 Fix version constants for version v1.3.x

Version 1.3.0

Collecting up a number of Issue fixes and PRs that have sat in the repository for a while, along with some small new features like topic_filter and topic_matcher.

The full list:

• Fixed building and using library as DLL on Windows with MSVC
• Updated License to Eclipse Public License v2.0
• Updated create and connect options to better deal with MQTT protocol version
• Defaulting connect version to v5 if specified in create options.
• Added a topic_filter class to match a single filter to specific topics.
• Added a topic_matcher class to create a collection of items in a trie structure that can contain items tied to topic filters. (Useful for queues or callbacks per-subscription topic).
• Minor tweaks to prepare for C++20
• Support for Catch2 v3.x for unit tests (v2.x also still supported).
• Changed the sample apps to use the newer "mqtt://" schemas.
• Connect option initializers for v5 and WebSockets.

Fixed Issues and Pull Requests:

• #343 async_client::try_consume_message_until taking single parameter fails to compile
• #445 Update properties when moving/copying connect options.
• #325 Cache connect options in client to keep memory valid for callbacks like SSL on_error()
• #361 Added missing LICENSE file to conform to GitHub conventions.
• #304 Missing create_options::DFLT_C_STRUCT symbol when linking with MSVC.
• [#429] (#411) Remove declaration of connect_options::to_string() with missing implementation.
• #411 Missing virtual keyword for some client methods
• #444 Unit tests to check that connect options builder sets properties.
• #313 Get unit tests building on Windows. Needed to get rid of make_unique<> for Windows
• #397 Doc about clean session in connect_options.h is wrong
• #442 g++ complains with multiple definition of static constexpr for mixed C++11/17 builds
• #445Fix copy/move constructor for connect/disconnect opts with properties
• #425 Silence warning for unused variable rsp in class unsubscribe_response
• #440 Fix typos across the project
• #428 Fixed type in create_options.h
• #407 Fix nodiscard warnings in sync client
• #385 Thread queue deadlock with multiple consumers
• #374 Add Paho C as a submodeule
• #350 avoid adding Paho MQTT C library twice
• #253 implicit capture of 'this' via '[=]' is deprecated in C++20
• #337 copy/move of caPath_ in ssl_options
• #330 added /build/ folder to .gitignore
• #317 String constructor using just len instead of end iterator.
• #323 Added Session Expiry Interval to v5 chat sample to test.

Version 1.2.0

This release brings in some missing MQTT v5 features, support for websocket headers and proxies, ALPN protocol lists, adds the builder pattern for options, and fixes a number of bugs in both the C++ library and the underlying C lib.

Requires Paho C v1.3.8

• Missing MQTT v5 features:
  • Ability to add properties to Subscribe and Unsubscribe packets (i.e. subscription identifiers)
  • "Disconnected" callback gives reason code and properties for server disconnect
• New create_options that can be used to construct a client with new features:
  • Send while disconnected before the 1st successful connection
  • Output buffer can delete oldest messages when full
  • Can choose to clear the persistence store on startup
  • Select whether to persist QoS 0 messages
• Started classes to create options using the Builder Pattern, with the create_options_builder, connect_options_builder, message_ptr_builder, etc.
• User-defined websocket HTTP headers.
• HTTP/S proxy support
• Added ALPN protocol support to SSL/TLS options
• SSL/TLS error and PSK callback support
• Update connection callback support (change credentials when using auto-reconnect)
• Updates to the sample apps:
  • Overall cleanup with better consistency
  • Example of using websockets and a proxy
  • User-based file persistence with simple encoding/encryption
  • Sharing a client between multiple threads
• Converted the unit tests to use Catch2
• All library exceptions are now properly derived from the mqtt::exception base class.
• [#231] Added on_disconnected callback to handle receipt of disconnect packet from server.
• [#211, #223, #235] Removed use of Log() function from the Paho C library.
• [#227] Fixed race condition in thread-safe queue
• [#224] & [#255] Subscribing to MQTT v3 broker with array of one topic causes segfault.
• [#282] Ability to build Debian/Ubuntu package
• [#300] Calling reconnect() was hanging forever, even when successful. In addition several of the synchronous client calls were hanging forever on failure. They now properly throw a timeout_error exception.
• Several memory issues and bug fixes from updated Paho C library support.

Version 1.1

This release was primarily to add MQTT v5 support and server responses.

• MQTT v5 support:
  • Properties
    • New property class acts something like a std::variant to hold a property of any supported type.
    • New properties class is a collection type to hold all the properties for a single transmitted packet.
    • Properties can be added to outbound messages and obtained from received messages.
    • Properties can also be obtained from server responses to requests such as from a connect call. These are available in the token objects when they complete.
  • The client object tracks the desired MQTT version that the app requested and/or is currently connected at. Internally this is now required by the response_options the need to distinguish between pre-v5 and post-v5 callback functions.
  • MQTT v5 reason codes for requests are available via token objects when they complete. They are also available in exception objects that are thrown by tokens.
  • Support for subscibe options, like no local subscriptions, etc.
  • Sample applications were added showing how to do basic Remote Procedure Calls (RPC's) with MQTT v5 using the RESPONSE_TOPIC and CORRELATION_DATA properties. These are rpc_math_cli and rpc_math_srvr in the src/samples directory.
  • A sample "chat" application was added, showing how to use subscribe options, such as "no local".
• More descriptive error messages (PR #154), integrated into the mqtt::exception class. MQTT v5 reason codes are also included in the exceptions when an error occurs.
• Applications can (finally) get server responses from the various ACK packets. These are available through the tokens after they complete, as connect_response, subscribe_response, and unsubscribe_response.
• The topic objects can be used to subscribe.
• Applications can register individual callback functions instead of using a callback interface object. This allows easy use of lambda functions for callbacks.
• The connect options can take a LWT as a plain message, via connect_options::set_will_message()
• New unit tests have started using Catch2.
• Tested with Paho C v1.3.1

Version 1.0.1

This is a bug-fix released aimed mainly at issues with the build system and working towards more "modern" usage of CMake. In addition:

• Support for Paho C v1.2.1
• Fixed a number of build issues, particularly on Windows
• Windows shared libraries (DLL's) now supported
• Several minor bug fixes

Version 1.0.0 (Paho 1.3)

The initial Paho C++ Client library for memory-managed platforms (Linux, Windows, etc).
Requires Paho C Client Library v1.2.

Supports MQTT 3.1 & 3.1.1, SSL/TLS, Asynchronous & Synchronous interfaces, persistence and off-line buffering, automatic reconnect, and high availability.

Version 0.5 Pre-release

This was the initial, unsupported, version of the library that was publicly available for several years before the official v1.0 release (which introduced a number of breaking changes).