2019, Web 为我们准备了什么

Web Assembly Use Cases

• Higher performance games (Unreal, Unity)
• Audio and Video codecs / 3D model compression
• Google Earth
• Speech synthesis / recognition
• Media applications (Photoshop, After Effects, Maya, Blender, etc.)
• Bring existing C/C++ apps to the Web (Linux Stack, Emacs, Vim)
• Libraries for cryptography, computer vision
• Applications requiring reliable performance, blocking APIs, precise memory control

Web Assembly

• Bring "low-level" code to the Web (C/C++)
• Implementations shipped in Chrome, Firefox, Safari, Edge, NodeJS
• Support in Rust, C/C++, C#/.Net, Java, Python, Go
• Properties
  • Binary format
  • Stack machine + locals/globals with type constraints
  • Structured control flow
  • Linear heap (ArrayBuffer -> SharedArrayBuffer)
  • On the Web, embedded in JS (WebAssembly object)

WASM Future

See WebAssembly/proposals

• Threads
• ECMAScript module integration
• BigInt<->i64 conversion in JS API
• 128-bit packed SIMD Extension
• Garbage collection

WebGPU

• GPU:
  • rendering onscreen and offscreen drawing surfaces
  • computation tasks
• Not a direct mapping of a native API
• Only a proposal, not on the standard track yet
• WSL: platform-neutral/portable Shading Language
• Could be implemented above Direct3D, Metal, or Vulkan.
• long-term direction to replace/complement WebGL

Contributing to the Web

• Explainer
• Find the right community/group
• WebIDL for APIs
• Step-by-step algorithms
• GitHub, Markdown, respec, bikeshed, etc.
• Get an early review w3ctag/design-reviews
• Write web-platform-tests (WPT) tests

Explainer

• What problem are you trying to solve?
• keep track of and make a note of alternatives which have been considered
• Be clear about the end-user need, first and foremost.
• The explainer is for everyone to read
• Check out the TAG documentation

Find the right community/group

You need to sell your idea

• Be open!
• Present your proposal in venuesL conferences, meetups, W3C TPAC
• W3C Community Groups: create your own (for bug ideas, like WASM, WebGPU) or use WICG
• Find other implementers
• Ask the W3C Staff for help in finding the right individuals to talk to

Web IDL for APIs

• interface definition language to describe API for the Web
• Best is to look at existing examples, like Payment Request API, Fetch, Intersection Observer
• Learn the design patternsL constructors, handlers, promises, etc.
• Make sure you know Javascript

specification

WebIDL for APIs

[SecureContext, Exposed=Window]
interface PaymentRequest : EventTarget {
  constructor(
    sequence<PaymentMethodData> methodData,
    PaymentDetailsInit details,
    optional PaymentOptions options = {}
  );
  [NewObject]
  Promise<PaymentResponse> show(optional Promise<PaymentDetailsUpdate> detailsPromise);
  readonly attribute DOMString? shippingOption;
}

WebIDL for APIs

[Exposed=(Window,Worker)]
interface Performance : EventTarget {
    DOMHighResTimeStamp now();
    readonly attribute DOMHighResTimeStamp timeOrigin;
    [Default] object toJSON();
};
partial interface mixin WindowOrWorkerGlobalScope {
    [Replaceable] readonly attribute Performance performance;
};

Step by step algorithm

Write the specification for implementers

The PaymentRequest(methodData, details, options) constructor MUST act as follows:

1. If the current settings object's responsible document is not allowed to use the "payment" feature, then throw a "SecurityError" DOMException.
2. Establish the request's id:
   1. If details.id is missing, add an id member to details and set its value to a UUID [RFC4122].
3. Let serializedMethodData be an empty list.
4. Process payment methods:
   1. If the length of the methodData sequence is zero, then throw a TypeError, optionally informing the developer that at least one payment method is required.

Tools

• Use GitHub to interact with your audience
• Explaier is written in markdown
• Specification should be written in respec or bikeshed

TAG review

• Get it as early as possible (complete explainer, draft of a spec). Do not wait!
• It's a two way communication
• Raise an issue w3ctag/design-reviews
• Check other issues for example

Write tests

• Unless you have tests, your feature won't get implementers traction
• web-platform-tests is the de facto Test project for the Web
• Consider adding WebDriver in your proposal if needed
• This helps writing your early implementation

谢谢！

问题?

https://www.w3.org/2019/Talks/shenzhen-2019-plh/

plh@w3.org