#----------------------------------------------------------------------------- # Copyright (c) 2012 - 2021, Anaconda, Inc., and Bokeh Contributors. # All rights reserved. # # The full license is in the file LICENSE.txt, distributed with this software. #----------------------------------------------------------------------------- ''' Assemble WebSocket wire message fragments into complete Bokeh Server message objects that can be processed. ''' #----------------------------------------------------------------------------- # Boilerplate #----------------------------------------------------------------------------- import logging # isort:skip log = logging.getLogger(__name__) #----------------------------------------------------------------------------- # Imports #----------------------------------------------------------------------------- # Bokeh imports from .exceptions import ValidationError #----------------------------------------------------------------------------- # Globals and constants #----------------------------------------------------------------------------- __all__ = ( 'Receiver', ) #----------------------------------------------------------------------------- # General API #----------------------------------------------------------------------------- #----------------------------------------------------------------------------- # Dev API #----------------------------------------------------------------------------- [docs]class Receiver: ''' Receive wire message fragments and assemble complete Bokeh server message objects. On ``MessageError`` or ``ValidationError``, the receiver will reset its state and attempt to consume a new message. The *fragment* received can be either bytes or unicode, depending on the transport's semantics (WebSocket allows both). .. code-block:: python [ # these are required b'{header}', # serialized header dict b'{metadata}', # serialized metadata dict b'{content}, # serialized content dict # these are optional, and come in pairs; header contains num_buffers b'{buf_header}', # serialized buffer header dict b'array' # raw buffer payload data ... ] The ``header`` fragment will have the form: .. code-block:: python header = { # these are required 'msgid' : <str> # a unique id for the message 'msgtype' : <str> # a message type, e.g. 'ACK', 'PATCH-DOC', etc # these are optional 'num_buffers' : <int> # the number of additional buffers, if any } The ``metadata`` fragment may contain any arbitrary information. It is not processed by Bokeh for any purpose, but may be useful for external monitoring or instrumentation tools. The ``content`` fragment is defined by the specific message type. ''' [docs] def __init__(self, protocol): ''' Configure a Receiver with a specific Bokeh protocol. Args: protocol (Protocol) : A Bokeh protocol object to use to assemble collected message fragments. ''' self._protocol = protocol self._current_consumer = self._HEADER self._message = None self._buf_header = None [docs] async def consume(self, fragment): ''' Consume individual protocol message fragments. Args: fragment (``JSON``) : A message fragment to assemble. When a complete message is assembled, the receiver state will reset to begin consuming a new message. ''' self._current_consumer(fragment) return self._message def _HEADER(self, fragment): self._assume_text(fragment) self._message = None self._partial = None self._fragments = [fragment] self._current_consumer = self._METADATA def _METADATA(self, fragment): self._assume_text(fragment) self._fragments.append(fragment) self._current_consumer = self._CONTENT def _CONTENT(self, fragment): self._assume_text(fragment) self._fragments.append(fragment) header_json, metadata_json, content_json = self._fragments[:3] self._partial = self._protocol.assemble(header_json, metadata_json, content_json) self._check_complete() def _BUFFER_HEADER(self, fragment): self._assume_text(fragment) self._buf_header = fragment self._current_consumer = self._BUFFER_PAYLOAD def _BUFFER_PAYLOAD(self, fragment): self._assume_binary(fragment) self._partial.assemble_buffer(self._buf_header, fragment) self._check_complete() def _check_complete(self): if self._partial.complete: self._message = self._partial self._current_consumer = self._HEADER else: self._current_consumer = self._BUFFER_HEADER def _assume_text(self, fragment): if not isinstance(fragment, str): raise ValidationError("expected text fragment but received binary fragment for %s" % (self._current_consumer.__name__)) def _assume_binary(self, fragment): if not isinstance(fragment, bytes): raise ValidationError("expected binary fragment but received text fragment for %s" % (self._current_consumer.__name__)) #----------------------------------------------------------------------------- # Private API #----------------------------------------------------------------------------- #----------------------------------------------------------------------------- # Code #-----------------------------------------------------------------------------