#----------------------------------------------------------------------------- # 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 a session object to service Bokeh documents in external Python clients to a Bokeh server. Use-Cases ~~~~~~~~~ A client session has two primary uses: * Implementing automated testing infrastructure around Bokeh server applications. * Creating and customizing specific sessions of a Bokeh server application (running *in the Bokeh server*) before passing them on to a specific viewer. ''' #----------------------------------------------------------------------------- # Boilerplate #----------------------------------------------------------------------------- from __future__ import annotations import logging # isort:skip log = logging.getLogger(__name__) #----------------------------------------------------------------------------- # Imports #----------------------------------------------------------------------------- # Standard library imports from typing import TYPE_CHECKING, Any, Literal from urllib.parse import quote_plus ## External imports if TYPE_CHECKING: from tornado.ioloop import IOLoop # Bokeh imports from ..core.types import ID from ..document import Document from ..resources import DEFAULT_SERVER_HTTP_URL, SessionCoordinates from ..util.browser import NEW_PARAM, BrowserLike, BrowserTarget from ..util.token import generate_jwt_token, generate_session_id from .states import ErrorReason from .util import server_url_for_websocket_url, websocket_url_for_server_url if TYPE_CHECKING: from ..document.events import DocumentPatchedEvent, SessionCallbackAdded, SessionCallbackRemoved from ..models.ui import UIElement from ..protocol.messages.patch_doc import patch_doc from ..protocol.messages.server_info_reply import ServerInfo from ..server.callbacks import DocumentCallbackGroup from .connection import ClientConnection #----------------------------------------------------------------------------- # Globals and constants #----------------------------------------------------------------------------- DEFAULT_SESSION_ID = "default" DEFAULT_SERVER_WEBSOCKET_URL = websocket_url_for_server_url(DEFAULT_SERVER_HTTP_URL) __all__ = ( 'ClientSession', 'pull_session', 'push_session', 'show_session', ) #----------------------------------------------------------------------------- # General API #----------------------------------------------------------------------------- def pull_session(session_id: ID | None = None, url: str = "default", io_loop: IOLoop | None = None, arguments: dict[str, str] | None = None, max_message_size: int = 20*1024*1024) -> ClientSession: ''' Create a session by loading the current server-side document. ``session.document`` will be a fresh document loaded from the server. While the connection to the server is open, changes made on the server side will be applied to this document, and changes made on the client side will be synced to the server. If you don't plan to modify ``session.document`` you probably don't need to use this function; instead you can directly ``show_session()`` or ``server_session()`` without downloading the session's document into your process first. It's much more efficient to avoid downloading the session if you don't need to. In a production scenario, the ``session_id`` should be unique for each browser tab, which keeps users from stomping on each other. It's neither scalable nor secure to use predictable session IDs or to share session IDs across users. For a notebook running on a single machine, ``session_id`` could be something human-readable such as ``"default"`` for convenience. If you allow ``pull_session()`` to generate a unique ``session_id``, you can obtain the generated ID with the ``id`` property on the returned ``ClientSession``. Args: session_id (string, optional) : The name of the session, None to autogenerate a random one (default: None) url : (str, optional): The URL to a Bokeh application on a Bokeh server can also be `"default"` which will connect to the default app URL io_loop (``tornado.ioloop.IOLoop``, optional) : The ``IOLoop`` to use for the websocket arguments (dict[str, str], optional) : A dictionary of key/values to be passed as HTTP request arguments to Bokeh application code (default: None) Note that should only be provided when pulling new sessions. If ``session_id`` is not None, or a session with ``session_id`` already exists, these arguments will have no effect. max_message_size (int, optional) : Configure the Tornado max websocket message size. (default: 20 MB) Returns: ClientSession : A new ``ClientSession`` connected to the server ''' coords = SessionCoordinates(session_id=session_id, url=url) session = ClientSession( session_id=session_id, websocket_url=websocket_url_for_server_url(coords.url), io_loop=io_loop, arguments=arguments, max_message_size=max_message_size) session.pull() return session def push_session(document: Document, session_id: ID | None = None, url: str = "default", io_loop: IOLoop | None = None, max_message_size: int = 20*1024*1024) -> ClientSession: ''' Create a session by pushing the given document to the server, overwriting any existing server-side document. ``session.document`` in the returned session will be your supplied document. While the connection to the server is open, changes made on the server side will be applied to this document, and changes made on the client side will be synced to the server. In a production scenario, the ``session_id`` should be unique for each browser tab, which keeps users from stomping on each other. It's neither scalable nor secure to use predictable session IDs or to share session IDs across users. For a notebook running on a single machine, ``session_id`` could be something human-readable such as ``"default"`` for convenience. If you allow ``push_session()`` to generate a unique ``session_id``, you can obtain the generated ID with the ``id`` property on the returned ``ClientSession``. Args: document : (bokeh.document.Document) The document to be pushed and set as session.document session_id : (string, optional) The name of the session, None to autogenerate a random one (default: None) url : (str, optional): The URL to a Bokeh application on a Bokeh server can also be `"default"` which will connect to the default app URL io_loop : (tornado.ioloop.IOLoop, optional) The IOLoop to use for the websocket max_message_size (int, optional) : Configure the Tornado max websocket message size. (default: 20 MB) Returns: ClientSession A new ClientSession connected to the server ''' coords = SessionCoordinates(session_id=session_id, url=url) session = ClientSession(session_id=coords.session_id, websocket_url=websocket_url_for_server_url(coords.url), io_loop=io_loop, max_message_size=max_message_size) session.push(document) return session def show_session( session_id: ID | None = None, url: str = "default", session: ClientSession | None = None, browser: str | None = None, new: BrowserTarget = "tab", controller: BrowserLike | None = None) -> None: ''' Open a browser displaying a session document. If you have a session from ``pull_session()`` or ``push_session`` you can ``show_session(session=mysession)``. If you don't need to open a connection to the server yourself, you can show a new session in a browser by providing just the ``url``. Args: session_id (string, optional) : The name of the session, None to autogenerate a random one (default: None) url : (str, optional): The URL to a Bokeh application on a Bokeh server can also be `"default"` which will connect to the default app URL session (ClientSession, optional) : session to get session ID and server URL from If you specify this, you don't need to specify session_id and url browser (str, optional) : browser to show with (default: None) For systems that support it, the **browser** argument allows specifying which browser to display in, e.g. "safari", "firefox", "opera", "windows-default" (see the :doc:`webbrowser ` module documentation in the standard lib for more details). new (str, optional) : new file output mode (default: "tab") For file-based output, opens or raises the browser window showing the current output file. If **new** is 'tab', then opens a new tab. If **new** is 'window', then opens a new window. ''' if session is not None: server_url = server_url_for_websocket_url(session._connection.url) session_id = session.id else: coords = SessionCoordinates(session_id=session_id, url=url) server_url = coords.url session_id = coords.session_id if controller is None: from bokeh.util.browser import get_browser_controller controller = get_browser_controller(browser=browser) controller.open(server_url + "?bokeh-session-id=" + quote_plus(session_id), new=NEW_PARAM[new]) class ClientSession: ''' Represents a websocket connection to a server-side session. Each server session stores a Document, which is kept in sync with the corresponding Document for this ``ClientSession`` instance. Updates on either side of the connection will automatically propagate to the other side, as long as the connection is open. ClientSession objects can (and usually should) be used as a context manager so that the session is properly closed: .. code-block:: python with pull_session(url=app_url) as mysession: # customize session here script = server_session(session_id=mysession.id, url=app_url) return render_template("embed.html", script=script, template="Flask") If you do not use ``ClientSession`` in this way, it is up to you to ensure that ``mysession.close()`` is called. .. autoclasstoc:: ''' _document: Document | None _id: ID _connection: ClientConnection _callbacks: DocumentCallbackGroup def __init__(self, session_id: ID | None = None, websocket_url: str = DEFAULT_SERVER_WEBSOCKET_URL, io_loop: IOLoop | None = None, arguments: dict[str, str] | None = None, max_message_size: int = 20*1024*1024): ''' A connection which attaches to a particular named session on the server. Always call either pull() or push() immediately after creating the session (until these are called ``session.document`` will be ``None``). The :func:`~bokeh.client.session.push_session` and :func:`~bokeh.client.session.pull_session()` functions will construct a ``ClientSession`` and push or pull in one step, so they are a good way to obtain a ``ClientSession``. Args: session_id (str) : The name of the session or None to generate one websocket_url (str) : Websocket URL to connect to io_loop (IOLoop, optional) : The IOLoop to use for the websocket arguments (dict[str, str], optional) : A dictionary of key/values to be passed as HTTP request arguments to Bokeh application code (default: None) Note that should only be provided when pulling new sessions. If ``session_id`` is not None, or a session with ``session_id`` already exists, these arguments will have no effect. max_message_size (int, optional) : Configure the Tornado max websocket message size. (default: 20 MB) ''' self._document = None self._id = self._ensure_session_id(session_id) from .connection import ClientConnection self._connection = ClientConnection(session=self, io_loop=io_loop, websocket_url=websocket_url, arguments=arguments, max_message_size=max_message_size) from ..server.callbacks import DocumentCallbackGroup self._callbacks = DocumentCallbackGroup(self._connection.io_loop) def __enter__(self) -> ClientSession: ''' ''' return self def __exit__(self, exc_type: Any, exc_value: Any, exc_traceback: Any) -> None: ''' ''' self.close() # Properties -------------------------------------------------------------- @property def connected(self) -> bool: ''' Whether this session is currently connected. ''' return self._connection.connected @property def error_reason(self) -> ErrorReason | None: return self._connection.error_reason @property def error_code(self) -> int | None: return self._connection.error_code @property def error_detail(self) -> str: return self._connection.error_detail @property def url(self) -> str: return self._connection.url @property def document(self) -> Document: ''' A |Document| that will be kept in sync with the corresponding ``Document`` on the server. This value is initialized when :func:`pull` or :func:`push` succeeds. It will be ``None`` until then. ''' return self._document @property def id(self) -> ID: ''' A unique ID for this session. ''' return self._id @property def token(self) -> str: ''' A JWT token to authenticate the session. ''' return generate_jwt_token(self.id) # Public methods ---------------------------------------------------------- def connect(self) -> None: ''' Connect to a Bokeh server at the configured URL. ''' self._connection.connect() def close(self, why: str = "closed") -> None: ''' Close the connection to the server. ''' self._connection.close(why) def force_roundtrip(self) -> None: ''' Force a round-trip request/reply to the server, sometimes needed to avoid race conditions. Mostly useful for testing. Outside of test suites, this method hurts performance and should not be needed. Returns: None ''' self._connection.force_roundtrip() def check_connection_errors(self) -> None: ''' Raises an error, when the connection could not have been established. Should be used, after a call to connect. Returns: None ''' if not self.connected: if self.error_reason is ErrorReason.HTTP_ERROR: if self.error_code == 404: raise OSError(f"Check your application path! The given Path is not valid: {self.url}") raise OSError(f"We received an HTTP-Error. Disconnected with error code: {self.error_code}, given message: {self.error_detail}") raise OSError("We failed to connect to the server (to start the server, try the 'bokeh serve' command)") def pull(self) -> None: ''' Pull the server's state and set it as session.document. If this is called more than once, session.document will be the same object instance but its contents will be overwritten. Automatically calls :func:`connect` before pulling. ''' self.connect() self.check_connection_errors() if self.document is None: doc = Document() else: doc = self.document self._connection.pull_doc(doc) if self.document is None: self._attach_document(doc) def push(self, document: Document | None = None) -> None: ''' Push the given document to the server and record it as ``session.document``. If this is called more than once, the Document has to be the same (or None to mean ``session.document``). .. note:: Automatically calls :func:`~connect` before pushing. Args: document (|Document|, optional) : The document that will be kept in sync with the server document. None to use ``session.document`` or create a new document. ''' if self.document is None: if document is None: doc = Document() else: doc = document else: if document is None: doc = self.document else: raise ValueError("Cannot push() a different document from existing session.document") self.connect() self.check_connection_errors() self._connection.push_doc(doc) if self._document is None: self._attach_document(doc) def request_server_info(self) -> ServerInfo: ''' Ask for information about the server. Returns: A dictionary of server attributes. ''' return self._connection.request_server_info() def show(self, obj: UIElement | None = None, browser: str | None = None, new: Literal["tab", "window"] = "tab") -> None: ''' Open a browser displaying this session. Args: obj (UIElement object, optional) : a Layout (Row/Column), Plot or Widget object to display. The object will be added to the session's document. browser (str, optional) : browser to show with (default: None) For systems that support it, the **browser** argument allows specifying which browser to display in, e.g. "safari", "firefox", "opera", "windows-default" (see the :doc:`webbrowser ` module documentation in the standard lib for more details). new (str, optional) : new file output mode (default: "tab") For file-based output, opens or raises the browser window showing the current output file. If **new** is 'tab', then opens a new tab. If **new** is 'window', then opens a new window. ''' if obj and obj not in self.document.roots: self.document.add_root(obj) show_session(session=self, browser=browser, new=new) # Internal methods -------------------------------------------------------- def _attach_document(self, document: Document) -> None: self._document = document self._document.callbacks.on_change_dispatch_to(self) self._callbacks.add_session_callbacks(self._document.session_callbacks) def _document_patched(self, event: DocumentPatchedEvent) -> None: if event.setter is self: log.debug("Not sending notification back to server for a change it requested") return # TODO (havocp): our "change sync" protocol is flawed # because if both sides change the same attribute at the # same time, they will each end up with the state of the # other and their final states will differ. self._connection._send_patch_document(self._id, event) @classmethod def _ensure_session_id(cls, session_id: ID | None) -> ID: if session_id is None: session_id = generate_session_id() return session_id def _handle_patch(self, message: patch_doc) -> None: message.apply_to_document(self.document, self) def _loop_until_closed(self) -> None: ''' Execute a blocking loop that runs and executes event callbacks until the connection is closed (e.g. by hitting Ctrl-C). This function is intended to facilitate testing ONLY. ''' self._connection.loop_until_closed() def _notify_disconnected(self) -> None: ''' Called by the ClientConnection we are using to notify us of disconnect. ''' if self.document is not None: self.document.remove_on_change(self) self._callbacks.remove_all_callbacks() def _session_callback_added(self, event: SessionCallbackAdded) -> None: self._callbacks.add_session_callback(event.callback) def _session_callback_removed(self, event: SessionCallbackRemoved) -> None: self._callbacks.remove_session_callback(event.callback) #----------------------------------------------------------------------------- # Dev API #----------------------------------------------------------------------------- #----------------------------------------------------------------------------- # Private API #----------------------------------------------------------------------------- #----------------------------------------------------------------------------- # Code #-----------------------------------------------------------------------------