DEVICE CLASSES

A device class is a scheme where user devices plugged into Energenie
product, can be referred to as objects within a user application.

It is a way of abstracting the on-air radio interface and Energenie
device specifics from a user application, such that the user can
code 'in the land of their devices'.


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REQUIREMENTS

YES 1. EXPRESSIVE: To be able to write expressive and compact applications,
   that talk in the vocabulary of physical devices.

   YES a. All known Energenie devices to be modelled as classes inside a
      device database, and the capabilities and operations on those devices
      pre-written so they can be reused by a user application.

   YES b. An easy way for users to map energenie device intents to user
      device intents (such as by wrapping custom object vocabulary around
      the standard energenie device vocabulary) - e.g. room.heat() rather
      than plug.on()

  e.g. first level device names such as my_radiator or my_plug,
  or second level device names such as bedroom_radiator and kitchen_kettle
  (things plugged into devices)

  This will hide the detail of how messages get encoded and transported,
  and allows users to focus ore on the intents of the application, rather
  than the implementation details.


HMM? 2. NAME REGISTRY: To be able to build a local registry of devices and their configurations,
   and refer to devices by name inside the application.

   YES a. to be configurable by learning (e.g. listen for messages such as
      a join message, and add the device to the registry)

   YES b. to be configurable by hand (e.g. hand entering the sensor id of
      a known device into the registry)

   YES c. to automatically build variables for the user program from the
      registry, so that users don't have to bother with lots of
      wiring up code every time their app starts.

   YES d. this registry must be persistable, e.g. save and restore to a disk file,
      so that on application startup, the device database is automatically loaded
      and objects created.

   HMM? e. the registry can be queried, such as 'find me all devices that are of
      type x' or 'find me all devices in location kitchen'.


HMM? 3. INTENTS: To be able to command and query devices in a way that represents
   meaningful device-based intents (such as tv.on() and tv.get_power())

   YES a. received data values to be cached for deferred query, such as get_power()

   POSSIBLE b. the last receipt time of data from a transmitting device to be known

   POSSIBLY c. the next expected receipt time of data from a transmitting device to be known

   POSSIBLY d. the last known state of a transmitting device to be known (e.g. switch state
      both by commanded state and retrieved state)


YES 4. AGNOSTIC: To be able to refer to user devices in an Energenie device agnostic way.

   e.g. it doesn't matter if the TV is plugged into a green button device,
   or a MiHome device. It is always tv.on() in the code.


YES 5. LEARN/DISCOVER: To be able to instigate and manage learn mode from within an app

   YES a. To send specific commands to green button devices so they can
      learn the pattern

   YES b. To sniff for any messages from MiHome devices and capture them
      for later analysis and turning into device objects

   YES c. To process MiHome join requests, and send MiHome join acks


YES 6. ABSTRACTED RADIO: To completely hide the user from the on-air radio interface

   YES a. choosing the correct radio frequency and modulation automatically

   YES b. choosing the correct physical layer configuration automatically,
      such as message repeats for certain devices


Not as part of this work, but this should at least be enabled
by the design

HMM? 7. PERFORMING: To be able to build a well performing system
   with very few message collisions and message losses

   POSSIBLE a. by dynamically learning report patterns of MiHome devices

   POSSIBLE b. by intelligently deferring and schedulling transmit messages
      to avoid transmit slots of reporting devices

   POSSIBLE c. to query device characteristics such as modulation scheme and msg repeats.
      also to estimate the transmit time of a particular message to help
      with message scheduling.


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DESIGN Devices.py

MOSTLY DONE,

remaining items to investigate:

  commanded state? (did we ask it to be on, when did we ask?)
  reported state? (did it tell us it is on, when did we learn it?)

  overall device state
    have we seen this device this run?
    when did we last hear from it?
    when did we last talk to it?
    when do we expect to next hear from it?

  yet unmodelled devices still to be usable to some degree
    for MiHome devices, a proxy class generated dynamically based on received message parameters.
    e.g. if it reports a TEMPERATURE field, then there should be an automatic get_temperature() method
    generated.

  possibly add callbacks such as when_turned_on() when_turned_off() etc.

(do we need to know what our last sent request is, vs last known reported state?
e.g. if we have sent a request but not heard a response yet, this means we think we asked
it to turn on, but we don't yet know if it has done that. Some devices can't report
back, but some can, so it would be nice to have a four stage state machine for on/off)

(note, would be good to be able to persist the last message received on disk,
so that when code restarts, it knows the last send/receive time that was last processed.
i.e. a resumable state machine persisted to disk)

(note, a message scheduler if inserted in the middle, would do callbacks to say
that the request has been processed, so timestamps can be updated. Also same scheduler
could handle retries perhaps, if the device is tx and rx, then when you send a switch
change, it would normally report back that the switch had changed, so if you don't
get it, or if it is in the wrong state, could retry a send again until it changes)

(note, inner variables might have two versions for some devices, the requested
value and the confirmed value. If they are different, it means might still be
waiting for a reply, so can't guarantee the command was received yet)


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DESIGN Registry.py

DONE


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DESIGN - air_interface adaptors for FSK and OOK

DONE


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DESIGN NOTES - registry data store

REQUIREMENT: I want a simple persistent kvp database with the following features:

YES: 1. A file format that is portable across all platforms
YES: 2. A file format that is human readable and easily editable
YES: 3. A simple read and write key/value abstraction in python with a full CRUD lifecycle
YES: 4. Doesn't have to be hugely efficient or store very large data sets
YES: MIT licence
YES: 6. A single python file
TODO: 7. Works out of the box with no changes on Python 2 and Python 3

Additionally, it might:

YES: 8. A option to add multi process locking later if required, but not
   included by default

   so that it could be used as a simple central database for multiple
   programs sharing the same data set.

POSSIBLE: 9. understand read only and read/write intents better

   when using configuration data and last known values, it is useful
   to keep them in the same single file, so it is easy to copy
   to other machines. Some data is naturally 'write once' and
   very configuration based. Some data is naturally 'write often'.
   It might be nice if these two types of data could appear in the same
   file, but the locking/performance and resilience issues be handled
   differently for the two classes of data - e.g. perhaps having
   two connections to the same database file, one in read only mode
   for config records, and one in read/write mode for last use data.
   There might also be different namespace prefixes in the file
   so that the key sets are separate, or there may be a way to
   link them so that when you read a record you get both the static
   config data and the fast changing last use data as a single
   record. But this then implies when you do an update, you
   probably want to update part of a record rather than the
   whole record.


Note: callbacks on when_updated() might be required


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PRESENT STATUS

Router written and integrated in energenie.loop()
Discovery behaviours written and tested ok
monitor_mihome works with a synthetic join and toggles switches
KVS implementation completed and all tests pass
Registry tests all complete
receive sequence counter tested
setup_tool implemented and tested in simulation
fixed testers to use new registry and device classes
auto create example written using example registry
all test harnesses now run as a group fine
works on hardware
works on python3 (after a fashion!)

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PLAN UP TO: MERGE BACK TO MASTER


----- RELEASE TESTING AND RELEASE

* update the test instructions and re-test everything before merge

* Any outstanding items on the list above, feed back into issues on the TODO list,
so that they get dealt with in a later pass

* merge to master after test

END