bokeh.application.application

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.

class Application(*handlers: Handler, metadata: Dict[str, Any] | None = None)

An Application is a factory for Document instances.

Public Data Attributes:

handlers	The ordered list of handlers this Application is configured with.
metadata	Arbitrary user-supplied metadata to associate with this application.
safe_to_fork
static_path	Path to any (optional) static resources specified by handlers.

Public Methods:

__init__(*handlers[, metadata])	Application factory.
add(handler)	Add a handler to the pipeline used to initialize new documents.
create_document()	Creates and initializes a document using the Application's handlers.
initialize_document(doc)	Fills in a new document using the Application's handlers.
on_server_loaded(server_context)	Invoked to execute code when a new session is created.
on_server_unloaded(server_context)	Invoked to execute code when the server cleanly exits.
on_session_created(session_context)	Invoked to execute code when a new session is created.
on_session_destroyed(session_context)	Invoked to execute code when a session is destroyed.
process_request(request)	Processes incoming HTTP request returning a dictionary of additional data to add to the session_context.

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__init__(*handlers: Handler, metadata: Dict[str, Any] | None = None) → None

Application factory.

Parameters

handlers (seq[Handler]) – List of handlers to call. The URL is taken from the first one only.

Keyword Arguments

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:

{
    "data": {
        "hi": "hi",
        "there": "there"
    },
    "url": "/myapp"
}

The user-supplied metadata is returned as-is under the "data" key in the blob.

add(handler: Handler) → None

Add a handler to the pipeline used to initialize new documents.

Parameters

handler (Handler) – a handler for this Application to use to process Documents

create_document() → bokeh.document.document.Document

Creates and initializes a document using the Application’s handlers.

initialize_document(doc: bokeh.document.document.Document) → None

Fills in a new document using the Application’s handlers.

on_server_loaded(server_context: bokeh.application.application.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.

on_server_unloaded(server_context: bokeh.application.application.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.

async on_session_created(session_context: bokeh.application.application.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.

async on_session_destroyed(session_context: bokeh.application.application.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.

process_request(request: tornado.httputil.HTTPServerRequest) → Dict[str, Any]

Processes incoming HTTP request returning a dictionary of additional data to add to the session_context.

Parameters

request – HTTP request

Returns

A dictionary of JSON serializable data to be included on the session context.

property handlers: Tuple[Handler, ...]

The ordered list of handlers this Application is configured with.

property metadata: Dict[str, Any] | None

Arbitrary user-supplied metadata to associate with this application.

property safe_to_fork: bool

property static_path: str | None

Path to any (optional) static resources specified by handlers.

class ServerContext

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.

abstract property sessions: List[ServerSession]

SessionContext instances belonging to this application.

Subclasses must implement this method.

class SessionContext(server_context: bokeh.application.application.ServerContext, session_id: ID)

A harness for server-specific information and tasks related to Bokeh sessions.

This base class is probably not of interest to general users.

__init__(server_context: bokeh.application.application.ServerContext, session_id: ID) → None

abstract with_locked_document(func: Callable[[bokeh.document.document.Document], Awaitable[None]]) → Awaitable[None]

Runs a function with the document lock held, passing the document to the function.

Subclasses must implement this method.

Parameters

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

abstract property destroyed: 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.

property id: ID

The unique ID for the session associated with this context.

property server_context: bokeh.application.application.ServerContext

The server context for this session context

bokeh.application Handlers