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¶

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

class ClientSession(session_id=None, websocket_url='ws://localhost:5006/ws', io_loop=None, arguments=None)[source]¶

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:

with pull_session(url=app_url) as session:
    # 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 session.close() is called.

__init__(session_id=None, websocket_url='ws://localhost:5006/ws', io_loop=None, arguments=None)[source]¶

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 push_session() and pull_session() functions will construct a ClientSession and push or pull in one step, so they are a good way to obtain a ClientSession.

Parameters:

Parameters:	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.

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.

close(why='closed')[source]¶: Close the connection to the server.

connect()[source]¶: Connect to a Bokeh server at the configured URL.

force_roundtrip()[source]¶

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

loop_until_closed(suppress_warning=False)[source]¶

Execute a blocking loop that runs and executes 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.

pull()[source]¶

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 connect() before pulling.

push(document=None)[source]¶

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 connect() before pushing.

Parameters:	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.

request_server_info()[source]¶

Ask for information about the server.

Returns:	A dictionary of server attributes.

show(obj=None, browser=None, new='tab')[source]¶

Open a browser displaying this session.

Parameters:

Parameters:	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.

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.

connected¶: Whether this session is currently connected.

document¶

A Document that will be kept in sync with the corresponding Document on the server.

This value is initialized when pull() or push() succeeds. It will be None until then.

id¶: A unique ID for this session.

pull_session(session_id=None, url='default', io_loop=None, arguments=None)[source]¶

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.

Parameters:	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.
Returns:	A new `ClientSession` connected to the server
Return type:	ClientSession

push_session(document, session_id=None, url='default', io_loop=None)[source]¶

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.

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.

Parameters:

Parameters:	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

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

show_session(session_id=None, url='default', session=None, browser=None, new='tab', controller=None)[source]¶

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.

Parameters:

Parameters:	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.

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.