alexafsm
========
- Finite-state machine library for building complex Alexa
conversations.
- Free software: Apache Software License 2.0.
Dialog agents need to keep track of the various pieces of information to
make decisions how to respond to a given user input. This is referred to
as context, session, or state tracking. As the dialog complexity
increases, this state-tracking logic becomes harder to write, debug, and
maintain. This library takes the finite-state machine design approach to
address this complexity. Developers using this library can model dialog
agents with first-class concepts such as states, attributes, transition,
and actions. Visualization and other tools are also provided to help
understand and debug complex FSM conversations.
Also check out our `blog
post <https://medium.com/@vha14/alexafsm-a-finite-state-machine-python-library-for-building-complex-alexa-skills-61c3af5a299d>`__.
Features
--------
- FSM-based library for building Alexa skills with complex dialog state
tracking.
- Tools to validate, visualize, and print the FSM graph.
- Support analytics with `VoiceLabs <http://voicelabs.co/>`__.
- Can be paired with any Python server library (Flask, CherryPy, etc.)
- Written in Python 3.6 (primarily for type annotation and string
interpolation).
Getting Started
---------------
Install from `PyPi <https://pypi.python.org/pypi/alexafsm>`__:
::
pip install alexafsm
Consult the `Alexa skill
search <https://github.com/allenai/alexafsm/tree/master/tests/skillsearch>`__
skill in the ``tests`` directory for details of how to write an
``alexafsm`` skill. An Alexa skill is composed of the following three
classes: ``SessionAttributes``, ``States``, and ``Policy``.
``SessionAttributes``
~~~~~~~~~~~~~~~~~~~~~
``SessionAttributes`` is a class that holds session attributes
(``alexa_request['session']['attributes']``) and any information we need
to keep track of dialog state. \* The core attributes are ``intent``,
``slots``, and ``state``. \* ``intent`` and ``slots`` map directly to
Alexa's concepts. \* ``slots`` should be of type ``Slots``, which in
turn is defined as a named tuple, one field for each slot type. In the
skill search example, ``Slots = namedtuple('Slots', ['query', 'nth']``).
This named tuple class should be specified in the class definition as
``slots_cls = Slots``. \* ``state`` holds the name of the current state
in the state machine. \* Each Alexa skill can contain arbitrary number
of additional attributes. If an attribute is not meant to be sent back
to Alexa server (e.g. so as to reduce the payload size), it should be
added to ``not_sent_fields``. In the skill search example, ``searched``
and ``first_time`` are not sent to Alexa server.
See the implementation of skill search skill's
```SessionAttributes`` <https://github.com/allenai/alexafsm/blob/master/tests/skillsearch/session_attributes.py>`__
``States``
~~~~~~~~~~
``States`` is a class that specifies most of the FSM and its behavior.
It holds a reference to a ``SessionAttributes`` object, the type of
which is specified by overriding the ``session_attributes_cls`` class
attribute. The FSM is specified by a list of parameter-less methods.
Consider the following method:
.. code:: python
@with_transitions(
{
'trigger': NEW_SEARCH,
'source': '*',
'prepare': 'm_search',
'conditions': 'm_has_result_and_query'
},
{
'trigger': NTH_SKILL,
'source': '*',
'conditions': 'm_has_nth',
'after': 'm_set_nth'
},
{
'trigger': PREVIOUS_SKILL,
'source': '*',
'conditions': 'm_has_previous',
'after': 'm_set_previous'
},
{
'trigger': NEXT_SKILL,
'source': '*',
'conditions': 'm_has_next',
'after': 'm_set_next'
},
{
'trigger': amazon_intent.NO,
'source': 'has_result',
'conditions': 'm_has_next',
'after': 'm_set_next'
}
)
def has_result(self) -> response.Response:
"""Offer a preview of a skill"""
attributes = self.attributes
query = attributes.query
skill = attributes.skill
asked_for_speech = ''
if attributes.first_time_presenting_results:
asked_for_speech = _you_asked_for(query)
if attributes.number_of_hits == 1:
skill_position_speech = 'The only skill I found is'
else:
skill_position_speech = f'The {ENGLISH_NUMBERS[attributes.skill_cursor]} skill is'
if attributes.first_time_presenting_results:
if attributes.number_of_hits > 6:
num_hits = f'Here are the top {MAX_SKILLS} results.'
else:
num_hits = f'I found {len(attributes.skills)} skills.'
skill_position_speech = f'{num_hits} {skill_position_speech}'
return response.Response(
speech=f"{asked_for_speech} "
f" {skill_position_speech} {_get_verbal_skill(skill)}."
f" {HEAR_MORE}",
card=f"Search for {query}",
card_content=f"""
Top result: {skill.name}
{_get_highlights(skill)}
""",
reprompt=DEFAULT_PROMPT
)
Each method encodes the following:
- The name of the method is also the name of a state (``describing``)
in the FSM.
- The method may be decorated with one or several transitions, using
``with_transitions`` decorators. Transitions can be inbound
(``source`` needs to be specified) or outbound (``dest`` needs to be
specified).
- Each method returns a ``Response`` object which is sent to Alexa.
- Transitions can be specified with ``prepare`` and ``conditions``
attributes. See https://github.com/tyarkoni/transitions for detailed
documentations. The values of these attributes are parameter-less
methods of the ``Policy`` class.
- The ``prepare`` methods are responsible for "actions" of the FSM such
as querying a database. The ``after`` methods are responsible for
updating the state after the transition completes. They are the only
methods responsible for side-effects, e.g. modifying the attributes
of the states. This design facilitates ease of debugging.
``Policy``
~~~~~~~~~~
``Policy`` is the class that holds everything together. It contains a
reference to a ``States`` object, the type of which is specified by
overriding the ``states_cls`` class attribute. A ``Policy`` object
initializes itself by constructing a FSM based on the ``States`` type.
``Policy`` class contains the following key methods:
- ``handle`` takes an Alexa request, parses it, and hands over all
intent requests to ``execute`` method.
- ``execute`` updates the policy's internal state with the request's
details (intent, slots, session attributes), then calls ``trigger``
to make the state transition. It then looks up the corresponding
response generating methods of the ``States`` class to generate a
response for Alexa.
- ``initialize`` will initialize a policy without any request.
- ``validate`` performs validation of a policy object based on
``Policy`` class definition and a intent schema json file. It looks
for intents that are not handled, invalid source/dest/prepare
specifications, and unreachable states. The test in
``test_skillsearch.py`` performs such validation as a test of
``alexafsm``.
The Alexa skill search skill in the ``tests`` directory also contains a
Flask-based server that shows how to use ``Policy`` in five lines of
code:
.. code:: python
@app.route('/', methods=['POST'])
def main():
req = flask_request.json
policy = Policy.initialize()
return json.dumps(policy.handle(req, settings.vi)).encode('utf-8')
Other Tools
-----------
``alexafsm`` supports validation, graph visualization, and printing of
the FSM.
Validation
~~~~~~~~~~
Simply initialize a ``Policy`` before calling ``validate``. This
function takes as input the path to the skill's Alexa intent schema json
file and performs the following checks:
- All Alexa intents have corresponding events/triggers in the FSM.
- All states have either inbound or outbound transitions.
- All transitions are specified with valid source and destination
states.
- All conditions and prepare actions are handled with methods in the
``Policy`` class.
Change Detection with Record and Playback
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When making code changes that are not supposed to impact a skill's
dialog logic, we may want a tool to check that the skill's logic indeed
stay the same. This is done by first recording
(``SkillSettings().record = True``) one or several sessions, making the
code change, then checking if the changed code still produces the same
set of dialogs (``SkillSettings().playback = True``). During playback,
calls to databases such as ElasticSearch can be fulfilled from data read
from files generated during the recording. This is done by decorating
the database call with ``recordable`` function. See `the ElasticSearch
call <https://github.com/allenai/alexafsm/blob/master/tests/skillsearch/clients.py#L40>`__
in Skill Search for an example usage.
Graph Visualization
~~~~~~~~~~~~~~~~~~~
``alexafsm`` uses the ``transitions`` library's API to draw the FSM
graph. For example, the skill search skill's FSM can be visualized using
the
`graph.py <https://github.com/allenai/alexafsm/blob/master/tests/skillsearch/bin/graph.py>`__.
invoked from
`graph.sh <https://github.com/allenai/alexafsm/blob/master/tests/skillsearch/bin/graph.sh>`__.
The resulting graph is displayed follow:
.. figure:: https://github.com/allenai/alexafsm/blob/master/tests/skillsearch/fsm.png
:alt: FSM Example
FSM Example
Graph Printout
~~~~~~~~~~~~~~
For complex graphs, it may be easier to inspect the FSM in text format.
Use the ``print_machine`` method to accomplish this. The output for the
skill search skill is below:
.. code:: text
Machine states:
bad_navigate, describe_ratings, describing, exiting, has_result, helping, initial, is_that_all, no_query_search, no_result, search_prompt
Events and transitions:
Event: NthSkill
Source: bad_navigate
bad_navigate -> bad_navigate, conditions: ['m_has_nth']
bad_navigate -> has_result, conditions: ['m_has_nth']
Source: describe_ratings
describe_ratings -> bad_navigate, conditions: ['m_has_nth']
describe_ratings -> has_result, conditions: ['m_has_nth']
Source: describing
describing -> bad_navigate, conditions: ['m_has_nth']
describing -> has_result, conditions: ['m_has_nth']
Source: exiting
exiting -> bad_navigate, conditions: ['m_has_nth']
exiting -> has_result, conditions: ['m_has_nth']
Source: has_result
has_result -> bad_navigate, conditions: ['m_has_nth']
has_result -> has_result, conditions: ['m_has_nth']
Source: helping
helping -> bad_navigate, conditions: ['m_has_nth']
helping -> has_result, conditions: ['m_has_nth']
Source: initial
initial -> bad_navigate, conditions: ['m_has_nth']
initial -> has_result, conditions: ['m_has_nth']
Source: is_that_all
is_that_all -> bad_navigate, conditions: ['m_has_nth']
is_that_all -> has_result, conditions: ['m_has_nth']
Source: no_query_search
no_query_search -> bad_navigate, conditions: ['m_has_nth']
no_query_search -> has_result, conditions: ['m_has_nth']
Source: no_result
no_result -> bad_navigate, conditions: ['m_has_nth']
no_result -> has_result, conditions: ['m_has_nth']
Source: search_prompt
search_prompt -> bad_navigate, conditions: ['m_has_nth']
search_prompt -> has_result, conditions: ['m_has_nth']
Event: PreviousSkill
Source: bad_navigate
bad_navigate -> bad_navigate, conditions: ['m_has_previous']
bad_navigate -> has_result, conditions: ['m_has_previous']
Source: describe_ratings
describe_ratings -> bad_navigate, conditions: ['m_has_previous']
describe_ratings -> has_result, conditions: ['m_has_previous']
Source: describing
describing -> bad_navigate, conditions: ['m_has_previous']
describing -> has_result, conditions: ['m_has_previous']
Source: exiting
exiting -> bad_navigate, conditions: ['m_has_previous']
exiting -> has_result, conditions: ['m_has_previous']
Source: has_result
has_result -> bad_navigate, conditions: ['m_has_previous']
has_result -> has_result, conditions: ['m_has_previous']
Source: helping
helping -> bad_navigate, conditions: ['m_has_previous']
helping -> has_result, conditions: ['m_has_previous']
Source: initial
initial -> bad_navigate, conditions: ['m_has_previous']
initial -> has_result, conditions: ['m_has_previous']
Source: is_that_all
is_that_all -> bad_navigate, conditions: ['m_has_previous']
is_that_all -> has_result, conditions: ['m_has_previous']
Source: no_query_search
no_query_search -> bad_navigate, conditions: ['m_has_previous']
no_query_search -> has_result, conditions: ['m_has_previous']
Source: no_result
no_result -> bad_navigate, conditions: ['m_has_previous']
no_result -> has_result, conditions: ['m_has_previous']
Source: search_prompt
search_prompt -> bad_navigate, conditions: ['m_has_previous']
search_prompt -> has_result, conditions: ['m_has_previous']
Event: NextSkill
Source: bad_navigate
bad_navigate -> bad_navigate, conditions: ['m_has_next']
bad_navigate -> has_result, conditions: ['m_has_next']
Source: describe_ratings
describe_ratings -> bad_navigate, conditions: ['m_has_next']
describe_ratings -> has_result, conditions: ['m_has_next']
Source: describing
describing -> bad_navigate, conditions: ['m_has_next']
describing -> has_result, conditions: ['m_has_next']
Source: exiting
exiting -> bad_navigate, conditions: ['m_has_next']
exiting -> has_result, conditions: ['m_has_next']
Source: has_result
has_result -> bad_navigate, conditions: ['m_has_next']
has_result -> has_result, conditions: ['m_has_next']
Source: helping
helping -> bad_navigate, conditions: ['m_has_next']
helping -> has_result, conditions: ['m_has_next']
Source: initial
initial -> bad_navigate, conditions: ['m_has_next']
initial -> has_result, conditions: ['m_has_next']
Source: is_that_all
is_that_all -> bad_navigate, conditions: ['m_has_next']
is_that_all -> has_result, conditions: ['m_has_next']
Source: no_query_search
no_query_search -> bad_navigate, conditions: ['m_has_next']
no_query_search -> has_result, conditions: ['m_has_next']
Source: no_result
no_result -> bad_navigate, conditions: ['m_has_next']
no_result -> has_result, conditions: ['m_has_next']
Source: search_prompt
search_prompt -> bad_navigate, conditions: ['m_has_next']
search_prompt -> has_result, conditions: ['m_has_next']
Event: AMAZON.NoIntent
Source: has_result
has_result -> bad_navigate, conditions: ['m_has_next']
has_result -> has_result, conditions: ['m_has_next']
Source: describe_ratings
describe_ratings -> is_that_all
Source: describing
describing -> search_prompt
Source: is_that_all
is_that_all -> search_prompt
Event: DescribeRatings
Source: bad_navigate
bad_navigate -> describe_ratings, conditions: ['m_has_result']
Source: describe_ratings
describe_ratings -> describe_ratings, conditions: ['m_has_result']
Source: describing
describing -> describe_ratings, conditions: ['m_has_result']
Source: exiting
exiting -> describe_ratings, conditions: ['m_has_result']
Source: has_result
has_result -> describe_ratings, conditions: ['m_has_result']
Source: helping
helping -> describe_ratings, conditions: ['m_has_result']
Source: initial
initial -> describe_ratings, conditions: ['m_has_result']
Source: is_that_all
is_that_all -> describe_ratings, conditions: ['m_has_result']
Source: no_query_search
no_query_search -> describe_ratings, conditions: ['m_has_result']
Source: no_result
no_result -> describe_ratings, conditions: ['m_has_result']
Source: search_prompt
search_prompt -> describe_ratings, conditions: ['m_has_result']
Event: AMAZON.YesIntent
Source: has_result
has_result -> describing
Source: describe_ratings
describe_ratings -> describing
Source: describing
describing -> exiting
Source: is_that_all
is_that_all -> exiting
Event: AMAZON.CancelIntent
Source: no_result
no_result -> exiting
Source: search_prompt
search_prompt -> exiting
Source: is_that_all
is_that_all -> exiting
Source: bad_navigate
bad_navigate -> exiting
Source: no_query_search
no_query_search -> exiting
Source: describing
describing -> is_that_all
Source: has_result
has_result -> is_that_all
Source: describe_ratings
describe_ratings -> is_that_all
Source: initial
initial -> search_prompt
Source: helping
helping -> search_prompt
Event: AMAZON.StopIntent
Source: no_result
no_result -> exiting
Source: search_prompt
search_prompt -> exiting
Source: is_that_all
is_that_all -> exiting
Source: bad_navigate
bad_navigate -> exiting
Source: no_query_search
no_query_search -> exiting
Source: describing
describing -> is_that_all
Source: has_result
has_result -> is_that_all
Source: describe_ratings
describe_ratings -> is_that_all
Source: initial
initial -> search_prompt
Source: helping
helping -> search_prompt
Event: NewSearch
Source: bad_navigate
bad_navigate -> exiting, conditions: ['m_searching_for_exit']
bad_navigate -> has_result, prepare: ['m_search'], conditions: ['m_has_result_and_query']
bad_navigate -> no_query_search, conditions: ['m_no_query_search']
bad_navigate -> no_result, prepare: ['m_search'], conditions: ['m_no_result']
Source: describe_ratings
describe_ratings -> exiting, conditions: ['m_searching_for_exit']
describe_ratings -> has_result, prepare: ['m_search'], conditions: ['m_has_result_and_query']
describe_ratings -> no_query_search, conditions: ['m_no_query_search']
describe_ratings -> no_result, prepare: ['m_search'], conditions: ['m_no_result']
Source: describing
describing -> exiting, conditions: ['m_searching_for_exit']
describing -> has_result, prepare: ['m_search'], conditions: ['m_has_result_and_query']
describing -> no_query_search, conditions: ['m_no_query_search']
describing -> no_result, prepare: ['m_search'], conditions: ['m_no_result']
Source: exiting
exiting -> exiting, conditions: ['m_searching_for_exit']
exiting -> has_result, prepare: ['m_search'], conditions: ['m_has_result_and_query']
exiting -> no_query_search, conditions: ['m_no_query_search']
exiting -> no_result, prepare: ['m_search'], conditions: ['m_no_result']
Source: has_result
has_result -> exiting, conditions: ['m_searching_for_exit']
has_result -> has_result, prepare: ['m_search'], conditions: ['m_has_result_and_query']
has_result -> no_query_search, conditions: ['m_no_query_search']
has_result -> no_result, prepare: ['m_search'], conditions: ['m_no_result']
Source: helping
helping -> exiting, conditions: ['m_searching_for_exit']
helping -> has_result, prepare: ['m_search'], conditions: ['m_has_result_and_query']
helping -> no_query_search, conditions: ['m_no_query_search']
helping -> no_result, prepare: ['m_search'], conditions: ['m_no_result']
Source: initial
initial -> exiting, conditions: ['m_searching_for_exit']
initial -> has_result, prepare: ['m_search'], conditions: ['m_has_result_and_query']
initial -> no_query_search, conditions: ['m_no_query_search']
initial -> no_result, prepare: ['m_search'], conditions: ['m_no_result']
Source: is_that_all
is_that_all -> exiting, conditions: ['m_searching_for_exit']
is_that_all -> has_result, prepare: ['m_search'], conditions: ['m_has_result_and_query']
is_that_all -> no_query_search, conditions: ['m_no_query_search']
is_that_all -> no_result, prepare: ['m_search'], conditions: ['m_no_result']
Source: no_query_search
no_query_search -> exiting, conditions: ['m_searching_for_exit']
no_query_search -> has_result, prepare: ['m_search'], conditions: ['m_has_result_and_query']
no_query_search -> no_query_search, conditions: ['m_no_query_search']
no_query_search -> no_result, prepare: ['m_search'], conditions: ['m_no_result']
Source: no_result
no_result -> exiting, conditions: ['m_searching_for_exit']
no_result -> has_result, prepare: ['m_search'], conditions: ['m_has_result_and_query']
no_result -> no_query_search, conditions: ['m_no_query_search']
no_result -> no_result, prepare: ['m_search'], conditions: ['m_no_result']
Source: search_prompt
search_prompt -> exiting, conditions: ['m_searching_for_exit']
search_prompt -> has_result, prepare: ['m_search'], conditions: ['m_has_result_and_query']
search_prompt -> no_query_search, conditions: ['m_no_query_search']
search_prompt -> no_result, prepare: ['m_search'], conditions: ['m_no_result']
Event: AMAZON.HelpIntent
Source: bad_navigate
bad_navigate -> helping
Source: describe_ratings
describe_ratings -> helping
Source: describing
describing -> helping
Source: exiting
exiting -> helping
Source: has_result
has_result -> helping
Source: helping
helping -> helping
Source: initial
initial -> helping
Source: is_that_all
is_that_all -> helping
Source: no_query_search
no_query_search -> helping
Source: no_result
no_result -> helping
Source: search_prompt
search_prompt -> helping
History
=======
0.1.0 (2017-02-23)
------------------
* First release on PyPI.