Metadata-Version: 1.0
Name: micropython-umqtt.simple
Version: 1.3.3
Summary: Lightweight MQTT client for MicroPython.
Home-page: https://github.com/micropython/micropython-lib
Author: MicroPython Developers
Author-email: micro-python@googlegroups.com
License: MIT
Description: umqtt.simple
        ============
        
        umqtt is a simple MQTT client for MicroPython. (Note that it uses some
        MicroPython shortcuts and doesn't work with CPython).
        
        Design requirements
        -------------------
        
        * Memory efficiency.
        * Avoid infamous design anti-patterns like "callback hell".
        * Support for both publishing and subscription via a single client
          object (another alternative would be to have separate client classes
          for publishing and subscription).
        
        API design
        ----------
        
        Based on the requirements above, there are following API traits:
        
        * All data related to MQTT messages is encoded as bytes. This includes
          both message content AND topic names (even though MQTT spec states
          that topic name is UTF-8 encoded). The reason for this is simple:
          what is received over network socket is binary data (bytes) and
          it would require extra step to convert that to a string, spending
          memory on that. Note that this applies only to topic names (because
          they can be both sent and received). Other parameters specified by
          MQTT as UTF-8 encoded (e.g. ClientID) are accepted as strings.
        * Subscribed messages are delivered via a callback. This is to avoid
          using a queue for subscribed messages, as otherwise they may be
          received at any time (including when client expects other type
          of server response, so there're 2 choices: either deliver them
          immediately via a callback or queue up until an "expected" response
          arrives). Note that lack of need for a queue is delusive: the
          runtime call stack forms an implicit queue in this case. And unlike
          explicit queue, it's much harder to control. This design was chosen
          because in a common case of processing subscribed messages it's
          the most efficient. However, if in subscription callback, new
          messages of QoS>0 are published, this may lead to deep, or
          infinite recursion (the latter means an application will terminate
          with ``RuntimeException``).
        
        API reference
        -------------
        
        Taking into account API traits described above, umqtt pretty closely
        follows MQTT control operations, and maps them to class methods:
        
        * ``connect(...)`` - Connect to a server. Returns True if this connection
          uses persisten session stored on a server (this will be always False if
          clean_session=True argument is used (default)).
        * ``disconnect()`` - Disconnect from a server, release resources.
        * ``ping()`` - Ping server (response is processed automatically by wait_msg()).
        * ``publish()`` - Publish a message.
        * ``subscribe()`` - Subscribe to a topic.
        * ``set_callback()`` - Set callback for received subscription messages.
        * ``set_last_will()`` - Set MQTT "last will" message. Should be called
          *before* connect().
        * ``wait_msg()`` - Wait for a server message. A subscription message will be
          delivered to a callback set with set_callback(), any other messages
          will be processed internally.
        * ``check_msg()`` - Check if there's pending message from server. If yes,
          process the same way as wait_msg(), if not, return immediately.
        
        ``wait_msg()`` and ``check_msg()`` are "main loop iteration" methods, blocking
        and non-blocking version. They should be called periodically in a loop,
        ``wait_msg()`` if you don't have any other foreground tasks to perform
        (i.e. your app just reacts to subscribed MQTT messages), ``check_msg()``
        if you process other foreground tasks too.
        
        Note that you don't need to call ``wait_msg()``/``check_msg()`` if you only
        publish messages, never subscribe to them.
        
        For more detailed information about API please see the source code
        (which is quite short and easy to review) and provided examples.
        
        
        Supported MQTT features
        -----------------------
        
        QoS 0 and 1 are supported for both publish and subscribe. QoS2 isn't
        supported to keep code size small. Besides ClientID, only "clean
        session" parameter is supported for connect as of now.
        
        
        MQTT client with automatic reconnect
        ------------------------------------
        
        There's a separate `umqtt.robust` module which builds on `umqtt.simple`
        and adds automatic reconnect support in case of network errors.
        Please see its documentation for further details.
        
Platform: UNKNOWN
