#----------------------------------------------------------------------------- # Copyright (c) 2012 - 2020, Anaconda, Inc., and Bokeh Contributors. # All rights reserved. # # The full license is in the file LICENSE.txt, distributed with this software. #----------------------------------------------------------------------------- ''' Provide the ``Application`` class. Application instances are factories for creating new Bokeh Documents. When a Bokeh server session is initiated, the Bokeh server asks the Application for a new Document to service the session. To do this, the Application first creates a new empty Document, then it passes this new Document to the ``modify_document`` method of each of its handlers. When all handlers have updated the Document, it is used to service the user session. ''' #----------------------------------------------------------------------------- # Boilerplate #----------------------------------------------------------------------------- import logging # isort:skip log = logging.getLogger(__name__) #----------------------------------------------------------------------------- # Imports #----------------------------------------------------------------------------- # Standard library imports from abc import ABCMeta, abstractmethod # Bokeh imports from ..document import Document from ..settings import settings #----------------------------------------------------------------------------- # Globals and constants #----------------------------------------------------------------------------- __all__ = ( 'Application', 'ServerContext', 'SessionContext', ) #----------------------------------------------------------------------------- # General API #----------------------------------------------------------------------------- #----------------------------------------------------------------------------- # Dev API #----------------------------------------------------------------------------- [docs]class Application: ''' An Application is a factory for Document instances. ''' # This is so that bokeh.io.show can check if a passed in object is an # Application without having to import Application directly. This module # depends on tornado and we have made a commitment that "basic" modules # will function without bringing in tornado. _is_a_bokeh_application_class = True [docs] def __init__(self, *handlers, **kwargs): ''' Application factory. Args: handlers (seq[Handler]): List of handlers to call. The URL is taken from the first one only. Keyword Args: metadata (dict): arbitrary user-supplied JSON data to make available with the application. The server will provide a URL ``http://applicationurl/metadata`` which returns a JSON blob of the form: .. code-block:: json { "data": { "hi": "hi", "there": "there" }, "url": "/myapp" } The user-supplied metadata is returned as-is under the ``"data"`` key in the blob. ''' metadata = kwargs.pop('metadata', None) if kwargs: raise TypeError("Invalid keyword argument: %s" % list(kwargs.keys())[0]) self._static_path = None self._handlers = [] self._metadata = metadata for h in handlers: self.add(h) # Properties -------------------------------------------------------------- @property def handlers(self): ''' The ordered list of handlers this Application is configured with. ''' return tuple(self._handlers) @property def metadata(self): ''' Arbitrary user-supplied metadata to associate with this application. ''' return self._metadata @property def safe_to_fork(self): ''' ''' return all(handler.safe_to_fork for handler in self._handlers) @property def static_path(self): ''' Path to any (optional) static resources specified by handlers. ''' return self._static_path # Public methods ---------------------------------------------------------- [docs] def add(self, handler): ''' Add a handler to the pipeline used to initialize new documents. Args: handler (Handler) : a handler for this Application to use to process Documents ''' self._handlers.append(handler) # make sure there is at most one static path static_paths = {h.static_path() for h in self.handlers} static_paths.discard(None) if len(static_paths) > 1: raise RuntimeError("More than one static path requested for app: %r" % list(static_paths)) elif len(static_paths) == 1: self._static_path = static_paths.pop() else: self._static_path = None [docs] def create_document(self): ''' Creates and initializes a document using the Application's handlers. ''' doc = Document() self.initialize_document(doc) return doc [docs] def initialize_document(self, doc): ''' Fills in a new document using the Application's handlers. ''' for h in self._handlers: # TODO (havocp) we need to check the 'failed' flag on each handler # and build a composite error display. In develop mode, we want to # somehow get these errors to the client. h.modify_document(doc) if h.failed: log.error("Error running application handler %r: %s %s ", h, h.error, h.error_detail) if settings.perform_document_validation(): doc.validate() [docs] def on_server_loaded(self, server_context): ''' Invoked to execute code when a new session is created. This method calls ``on_server_loaded`` on each handler, in order, with the server context passed as the only argument. ''' for h in self._handlers: h.on_server_loaded(server_context) [docs] def on_server_unloaded(self, server_context): ''' Invoked to execute code when the server cleanly exits. (Before stopping the server's ``IOLoop``.) This method calls ``on_server_unloaded`` on each handler, in order, with the server context passed as the only argument. .. warning:: In practice this code may not run, since servers are often killed by a signal. ''' for h in self._handlers: h.on_server_unloaded(server_context) [docs] async def on_session_created(self, session_context): ''' Invoked to execute code when a new session is created. This method calls ``on_session_created`` on each handler, in order, with the session context passed as the only argument. May return a ``Future`` which will delay session creation until the ``Future`` completes. ''' for h in self._handlers: await h.on_session_created(session_context) return None [docs] async def on_session_destroyed(self, session_context): ''' Invoked to execute code when a session is destroyed. This method calls ``on_session_destroyed`` on each handler, in order, with the session context passed as the only argument. Afterwards, ``session_context.destroyed`` will be ``True``. ''' for h in self._handlers: await h.on_session_destroyed(session_context) return None [docs] def process_request(self, request): ''' Processes incoming HTTP request returning a dictionary of additional data to add to the session_context. Args: request: HTTP request Returns: A dictionary of JSON serializable data to be included on the session context. ''' request_data = {} for h in self._handlers: request_data.update(h.process_request(request)) return request_data [docs]class ServerContext(metaclass=ABCMeta): ''' A harness for server-specific information and tasks related to collections of Bokeh sessions. *This base class is probably not of interest to general users.* ''' # Properties -------------------------------------------------------------- @property @abstractmethod def sessions(self): ''' ``SessionContext`` instances belonging to this application. *Subclasses must implement this method.* ''' pass # Public methods ---------------------------------------------------------- [docs] @abstractmethod def add_next_tick_callback(self, callback): ''' Add a callback to be run on the next tick of the event loop. *Subclasses must implement this method.* Args: callback (callable) : a callback to add The callback will execute on the next tick of the event loop, and should have the form ``def callback()`` (i.e. it should not accept any arguments) Returns: an ID that can be used with ``remove_next_tick_callback``. ''' pass [docs] @abstractmethod def add_periodic_callback(self, callback, period_milliseconds): ''' Add a callback to be run periodically until it is removed. *Subclasses must implement this method.* Args: callback (callable) : a callback to add The callback will execute periodically on the event loop as specified, and should have the form ``def callback()`` (i.e. it should not accept any arguments) period_milliseconds (int) : number of milliseconds to wait between executing the callback. Returns: an ID that can be used with ``remove_periodic_callback``. ''' pass [docs] @abstractmethod def add_timeout_callback(self, callback, timeout_milliseconds): ''' Add a callback to be run once after timeout_milliseconds. *Subclasses must implement this method.* Args: callback (callable) : a callback to add The callback will execute once on the event loop after the timeout has passed, and should have the form ``def callback()`` (i.e. it should not accept any arguments) timeout_milliseconds (int) : number of milliseconds to wait before executing the callback. Returns: an ID that can be used with ``remove_timeout_callback``. ''' pass [docs] @abstractmethod def remove_next_tick_callback(self, callback_id): ''' Remove a callback added with ``add_next_tick_callback``, before it runs. *Subclasses must implement this method.* Args: callback_id : the ID returned from ``add_next_tick_callback`` ''' pass [docs] @abstractmethod def remove_periodic_callback(self, callback_id): ''' Removes a callback added with ``add_periodic_callback``. *Subclasses must implement this method.* Args: callback_id : the ID returned from ``add_periodic_callback`` ''' pass [docs] @abstractmethod def remove_timeout_callback(self, callback_id): ''' Remove a callback added with ``add_timeout_callback``, before it runs. *Subclasses must implement this method.* Args: callback_id : the ID returned from ``add_timeout_callback`` ''' pass [docs]class SessionContext(metaclass=ABCMeta): ''' A harness for server-specific information and tasks related to Bokeh sessions. *This base class is probably not of interest to general users.* ''' [docs] def __init__(self, server_context, session_id): ''' ''' self._server_context = server_context self._id = session_id # Properties -------------------------------------------------------------- @property @abstractmethod def destroyed(self): ''' If ``True``, the session has been discarded and cannot be used. A new session with the same ID could be created later but this instance will not come back to life. ''' pass @property def id(self): ''' The unique ID for the session associated with this context. ''' return self._id @property def server_context(self): ''' The server context for this session context ''' return self._server_context # Public methods ---------------------------------------------------------- [docs] @abstractmethod def with_locked_document(self, func): ''' Runs a function with the document lock held, passing the document to the function. *Subclasses must implement this method.* Args: func (callable): function that takes a single parameter (the Document) and returns ``None`` or a ``Future`` Returns: a ``Future`` containing the result of the function ''' pass #----------------------------------------------------------------------------- # Private API #----------------------------------------------------------------------------- #----------------------------------------------------------------------------- # Code #-----------------------------------------------------------------------------