Bokeh 3.0 Iteration Plan

[mattpap]

This document outlines the timeline and tasks to accomplish for Bokeh 3.0 major release.

Date	Event
28 Oct 2021	Bokeh 3.0-dev1
9 Dec 2021	Bokeh 3.0-dev2
6 Jan 2022	Bokeh 3.0-dev3
27 Jan 2022	Bokeh 3.0-dev4
3 Mar 2022	Bokeh 3.0-dev5
27 Apr 2022	Bokeh 3.0-dev6
13 Jun 2022	Bokeh 3.0-dev7
24 Jun 2022	Bokeh 3.0-dev8
1 Jul 2022	Bokeh 3.0-dev9
5 Jul 2022	Bokeh 3.0-dev10
4 Aug 2022	Bokeh 3.0-dev11
8 Aug 2022	Bokeh 3.0-dev12
20 Aug 2022	Bokeh 3.0-dev13
27 Aug 2022	Bokeh 3.0-dev14
3 Sep 2022	Bokeh 3.0-dev15
13 Sep 2022	Bokeh 3.0-dev16
17 Sep 2022	Bokeh 3.0-dev17
17 Sep 2022	Bokeh 3.0-dev18
01 Oct 2022	Bokeh 3.0-dev19
09 Oct 2022	Bokeh 3.0-dev20
11 Oct 2022	Bokeh 3.0 RC1 Release
11 Oct 2022	Bokeh 3.0 RC2 Release
11 Oct 2022	Bokeh 3.0 RC3 Release
19 Oct 2022	Bokeh 3.0 RC4 Release
31 Oc 2022	Bokeh 3.0 Final Release

Major features and changes

1. Drop support for legacy (pre ES6) browsers, in particular IE. Remove polyfills and migrate to modern APIs. Establish minimal viable versions of major web browsers supported by bokehjs. Possibly establish a scheme for rolling phaseout of obsolete versions.
2. Robustify serialization protocol and related APIs. Introduce a robust intermediate (serializable) representation. Allow for universal handling of binary buffers. Possibly add support for fully binary protocol.
3. Modularize bokehjs' CSS. Migrate to shadow DOM and isolate each bokehjs components' styles. Establish an "API" for defining robust themes for external usage.
4. Make bokeh's layout interoperate with CSS better. Respect DOM/CSS instead of working around it. Focus on performance of large dashboards and ease of embedding into existing HTML/CSS.
5. Robustify in-canvas positioning schemes. Add support for sub-coordinates and mapping between coordinate systems. Allow multiple plots on a single canvas and arbitrary positioning of frames. (postponed to 3.1)
6. Further robustify WebGL-based rendering backend. Focus on the robustness of the implementation and coverage of previously not implemented cases (glyphs, hatch patterns, line joints, etc.).

[mattpap]

The remaining sub-tasks to finalize the release:

• Establish a migration path and/or compatibility mode after CSS modularization (see Stability of new DOM #12082).
• Finalize layout redesign (Redesign the layout using CSS and canvas layouts #11915).
• Update jupyter-bokeh (etc.) to work with the serialization changes implemented so far.
• Widget tooltips and general improvements to components and widgets (Generalize tooltips and add description to widgets #12154).
• Finalize canvas/positioning redesign (Redesign canvas, painting, positioning and UI events #12083). (postponed to 3.1)

Stretch goals:

• Add fully binary serialization protocol (Add support for binary serialization #12043). (postponed to 3.x)