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.
- New
- 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 inexception
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".
- Properties
- 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
, andunsubscribe_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
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
The initial Paho C++ Client library for memory-managed platforms (Linux, Windows, etc).
- Requires Paho C Client Library v1.2.
- MQTT 3.1 & 3.1.1
- SSL/TLS
- Asynchronous & Synchronous interfaces
- Persistence and off-line buffering
- Automatic reconnect
- High availability.