#-----------------------------------------------------------------------------
# Copyright (c) 2012 - 2022, 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
#-----------------------------------------------------------------------------
from __future__ import annotations
import logging # isort:skip
log = logging.getLogger(__name__)
#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------
# Standard library imports
from abc import ABCMeta, abstractmethod
from typing import (
TYPE_CHECKING,
Any,
Awaitable,
Callable,
ClassVar,
)
# Bokeh imports
from ..core.types import ID
from ..document import Document
from ..settings import settings
if TYPE_CHECKING:
from tornado.httputil import HTTPServerRequest
from typing_extensions import TypeAlias
from ..server.session import ServerSession
from .handlers.handler import Handler
#-----------------------------------------------------------------------------
# Globals and constants
#-----------------------------------------------------------------------------
__all__ = (
'Application',
'ServerContext',
'SessionContext',
)
#-----------------------------------------------------------------------------
# General API
#-----------------------------------------------------------------------------
#-----------------------------------------------------------------------------
# Dev API
#-----------------------------------------------------------------------------
Callback: TypeAlias = Callable[[], None]
[docs]class Application:
''' An Application is a factory for Document instances.
.. autoclasstoc::
'''
# 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: ClassVar[bool] = True
_static_path: str | None
_handlers: list[Handler]
_metadata: dict[str, Any] | None
[docs] def __init__(self, *handlers: Handler, metadata: dict[str, Any] | None = None) -> None:
''' 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.
'''
self._static_path = None
self._handlers = []
self._metadata = metadata
for h in handlers:
self.add(h)
# Properties --------------------------------------------------------------
@property
def handlers(self) -> tuple[Handler, ...]:
''' The ordered list of handlers this Application is configured with.
'''
return tuple(self._handlers)
@property
def metadata(self) -> dict[str, Any] | None:
''' Arbitrary user-supplied metadata to associate with this application.
'''
return self._metadata
@property
def safe_to_fork(self) -> bool:
'''
'''
return all(handler.safe_to_fork for handler in self._handlers)
@property
def static_path(self) -> str | None:
''' Path to any (optional) static resources specified by handlers.
'''
return self._static_path
# Public methods ----------------------------------------------------------
[docs] def add(self, handler: Handler) -> None:
''' 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) -> Document:
''' Creates and initializes a document using the Application's handlers.
'''
doc = Document()
self.initialize_document(doc)
return doc
[docs] def initialize_document(self, doc: Document) -> None:
''' 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: ServerContext) -> None:
''' 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: ServerContext) -> None:
''' 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: SessionContext) -> None:
''' 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: SessionContext) -> None:
''' 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: HTTPServerRequest) -> dict[str, Any]:
''' 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: dict[str, Any] = {}
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) -> list[ServerSession]:
''' ``SessionContext`` instances belonging to this application.
*Subclasses must implement this method.*
'''
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.*
'''
_server_context: ServerContext
_id: ID
[docs] def __init__(self, server_context: ServerContext, session_id: ID) -> None:
'''
'''
self._server_context = server_context
self._id = session_id
# Properties --------------------------------------------------------------
@property
@abstractmethod
def destroyed(self) -> bool:
''' 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) -> ID:
''' The unique ID for the session associated with this context.
'''
return self._id
@property
def server_context(self) -> ServerContext:
''' The server context for this session context
'''
return self._server_context
# Public methods ----------------------------------------------------------
[docs] @abstractmethod
def with_locked_document(self, func: Callable[[Document], Awaitable[None]]) -> Awaitable[None]:
''' 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
SessionDestroyedCallback = Callable[[SessionContext], None]
#-----------------------------------------------------------------------------
# Private API
#-----------------------------------------------------------------------------
#-----------------------------------------------------------------------------
# Code
#-----------------------------------------------------------------------------