Source code for bokeh.client.session

''' 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.

Note About "External" Applications
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
{warning}

'''
from __future__ import absolute_import, print_function

import logging
log = logging.getLogger(__name__)

from six.moves.urllib.parse import quote_plus

from ..document import Document
from ..resources import _SessionCoordinates, DEFAULT_SERVER_HTTP_URL
from ..util.browser import NEW_PARAM
from ..util.deprecation import deprecated
from ..util.session_id import generate_session_id
from ..util.string import format_docstring

from .util import server_url_for_websocket_url, websocket_url_for_server_url

DEFAULT_SESSION_ID = "default"

DEFAULT_SERVER_WEBSOCKET_URL = websocket_url_for_server_url(DEFAULT_SERVER_HTTP_URL)

_BOKEH_CLIENT_APP_WARNING_BODY = """
The use of `session.loop_until_closed` and `push_session` to run Bokeh
application code outside a Bokeh server is **HIGHLY DISCOURAGED** for any real
use.

Running application code outside a Bokeh server with bokeh.client in this way
has (and always will have) several intrinsic drawbacks:

* Fast binary array transport is NOT available! Base64 fallback is much slower
* All network traffic is DOUBLED due to extra hop between client and server
* Server *and* client process must be running at ALL TIMES for callbacks to work
* App code run outside the Bokeh server is NOT SCALABLE behind a load balancer

The bokeh.client API is recommended to use ONLY for testing, or for customizing
individual sessions running in a full Bokeh server, before passing on to viewers.

For information about different ways of running apps in a Bokeh server, see:

    http://bokeh.pydata.org/en/latest/docs/user_guide/server.html
"""

BOKEH_CLIENT_APP_WARNING = "\n\n    !!!! PLEASE NOTE !!!!\n" + _BOKEH_CLIENT_APP_WARNING_BODY

[docs]def push_session(document, session_id=None, url='default', app_path=None, io_loop=None): ''' 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 Returns: ClientSession A new ClientSession connected to the server ''' if app_path is not None: deprecated((0, 12, 5), "app_path", "url", "Now pass entire app URLS in the url arguments, e.g. 'url=http://foo.com:5010/bar/myapp''") url = url + app_path 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) session.push(document) return session
[docs]def pull_session(session_id=None, url='default', app_path=None, io_loop=None): ''' 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 Returns: ClientSession : A new ClientSession connected to the server ''' if app_path is not None: deprecated((0, 12, 5), "app_path", "url", "Now pass entire app URLS in the url arguments, e.g. 'url=http://foo.com:5010/bar/myapp'") url = url + app_path 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) session.pull() return session
[docs]def show_session(session_id=None, url='default', app_path=None, session=None, browser=None, new="tab", controller=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 ``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 app_path is not None: deprecated((0, 12, 5), "app_path", "url", "Now pass entire app URLS in the url arguments, e.g. 'url=http://foo.com:5010/bar/myapp'") url = url + app_path 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])
[docs]class ClientSession(object): ''' Represents a websocket connection to a server-side session. Each server session stores a Document, which is kept in sync with the document in this ClientSession instance. Always call either pull() or push() immediately after creating the session, if you construct a session by hand. '''
[docs] def __init__(self, session_id=None, websocket_url=DEFAULT_SERVER_WEBSOCKET_URL, io_loop=None): ''' 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 ''' 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) from ..server.callbacks import _DocumentCallbackGroup self._callbacks = _DocumentCallbackGroup(self._connection.io_loop)
def _attach_document(self, document): self._document = document self._document.on_change_dispatch_to(self) self._callbacks.add_session_callbacks(self._document.session_callbacks)
[docs] def pull(self): ''' 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() if not self._connection.connected: raise IOError("Cannot pull session document because we failed to connect to the server (to start the server, try the 'bokeh serve' command)") 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)
[docs] def push(self, document=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 (:class:`~bokeh.document.Document`, optional) : The document which 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() if not self._connection.connected: raise IOError("Cannot push session document because we failed to connect to the server (to start the server, try the 'bokeh serve' command)") self._connection.push_doc(doc) if self._document is None: self._attach_document(doc)
[docs] def show(self, obj=None, browser=None, new="tab"): ''' Open a browser displaying this session. Args: obj (LayoutDOM 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 ``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)
@classmethod def _ensure_session_id(cls, session_id): if session_id is None: session_id = generate_session_id() return session_id @property def document(self): ''' A :class:`~bokeh.document.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): ''' A unique ID for this session. ''' return self._id @property def connected(self): ''' Whether this session is currently connected. ''' return self._connection.connected
[docs] def connect(self): ''' Connect to a Bokeh server at the configured URL. ''' self._connection.connect()
[docs] def close(self, why="closed"): ''' Close the connection to the server. ''' self._connection.close(why)
[docs] def loop_until_closed(self, suppress_warning=False): ''' Execute a blocking loop that runs and exectutes event callbacks until the connection is closed (e.g. by hitting Ctrl-C). While this method can be used to run Bokeh application code "outside" the Bokeh server, this practice is HIGHLY DISCOURAGED for any real use case. ''' import warnings if not suppress_warning: warnings.warn(BOKEH_CLIENT_APP_WARNING) self._connection.loop_until_closed()
[docs] def request_server_info(self): ''' Ask for information about the server. Returns: A dictionary of server attributes. ''' return self._connection.request_server_info()
[docs] def force_roundtrip(self): ''' 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 _notify_disconnected(self): ''' 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 _document_patched(self, event): 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) def _handle_patch(self, message): message.apply_to_document(self.document, self) def _session_callback_added(self, event): self._callbacks.add_session_callback(event.callback) def _session_callback_removed(self, event): self._callbacks.remove_session_callback(event.callback)
__doc__ = format_docstring(__doc__, warning=_BOKEH_CLIENT_APP_WARNING_BODY)