Delete interface.md (obsolete document).

Just points to the main spec document.

Author: mgiuca

docs/interface.md

@@ -1,210 +1,3 @@
 # Web Share Target API Interface
 
-**Date**: 2017-01-12
-
-This document is a rough spec (i.e., *not* a formal web standard draft) of the
-Web Share Target API. This API allows websites to register to receive shared
-content from either the [Web Share API](https://github.com/mgiuca/web-share), or
-system events (e.g., shares from native apps).
-
-This API has 2 proposed designs: both require the user agent to support [web
-app manifests](https://www.w3.org/TR/appmanifest/), while the second requires
-support for [service workers](https://www.w3.org/TR/service-workers/). We are
-planning to explore both approaches to determine which is more acceptable. The
-[Web Share API](https://github.com/mgiuca/web-share) is not required, but
-recommended.
-
-Examples of using the Share Target API for sharing can be seen in the
-[explainer document](explainer.md).
-
-**Note**: The Web Share Target API is a proposal of the [Ballista
-project](https://github.com/chromium/ballista), which aims to explore
-website-to-website and website-to-native interoperability.
-
-## App manifest
-
-The first thing a handler needs to do is declare its share handling capabilities
-in its [web app manifest](https://www.w3.org/TR/appmanifest/):
-
-### Approach 1:
-
-We expect apps that are sharing data to share one or more fields, including
-title, text, and URL. These fields can be passed to the target app as query
-parameters, and each is optional. If a web app can handle a share, they should
-include (in the manifest) a template URL (relative to the manifest URL) that the
-shared data can be inserted into.
-
-```WebIDL
-dictionary ShareTarget {
-  DOMString url_template;
-};
-
-partial dictionary Manifest {
-  ShareTarget share_target;
-};
-```
-
-The `url_template` member will contain placeholders for each field of the form
-"{field}". Each placeholder in the template will be replaced with the value of
-the corresponding field, that has been shared by the source app. If a given
-field was not shared, its placeholder will be replaced with an empty string.
-An example url template is here:
-
-```json
-"share_target": {
-  "url_template": "/share?title={title}&text={text}&url={url}"
-}
-```
-
-The `url_template` member also allows the target web app to specify which
-attributes of the shared data it cares about. e.g. for Web Share, the passed
-data includes title, text, and URL, but the receiving web app may only care
-about message and URL.
-
-### Approach 2:
-
-```WebIDL
-partial dictionary Manifest {
-  boolean supports_share;
-};
-```
-The `"supports_share"` member of the manifest, if `true`, indicates that the app
-can receive share events from requesters, or the system.
-
-### Things to note
-
-The declarative nature of the manifest allows search services to index and
-present web applications that handle shares.
-
-Handlers declaring `supports_share` or `url_template` in their manifest
-will **not** be automatically registered; the user must explicitly authorize
-the registration. How this takes place is still under consideration (see [User
-Flow](explainer.md#user-flow), but will ultimately be at the discretion of the
-user agent (the user may be automatically prompted, or may have to explicitly
-request registration).
-
-**For consideration**: We may wish to provide a method for websites to
-explicitly request to prompt the user for handler registration. There would
-still be a requirement to declare `supports_share` in the manifest. For now,
-we have omitted such a method from the design to keep control in the hands of
-user agents. It is easier to add such a method later than remove it.
-
-## Handling incoming shares
-
-### Approach 1
-
-Recall the URL template from "Approach 1":
-
-`
-/share?title={title}&text={text}&url={url}
-`
-
-This will be filled with the share data, and opened by the browser, when the
-user selects the target app.
-
-For example, if a source app shares the data:
-
-```JSON
-{
-  "title": "Web Share Target API",
-  "text": "An API that allows web apps to receive shared data",
-  "url": "https://github.com/WICG/web-share-target"
-}
-```
-
-The browser will then launch the picker UI, and the user picks some target
-app. If the target app is www.example.com, the browser will launch the
-following URL in a new window or tab:
-
-`
-https://www.example.com/share?title=Web%20Share%20Target%20API&text=An%20API%20that%20allows%20web%20apps%20to%20receive%20shared%20data&url=https://github.com/WICG/web-share-target
-`
-
-Thus, the receiving web app should handle the shared data as desired, at that
-URL.
-
-### Approach 2
-
-Handlers **must** have a registered [service
-worker](https://www.w3.org/TR/service-workers/).
-
-When the user picks a registered web app as the target of a share, the
-handler's service worker starts up (if it is not already running), and a
-`"share"` event is fired at the global object.
-
-```WebIDL
-partial interface WorkerGlobalScope {
-  attribute EventHandler onshare;
-};
-
-interface ShareEvent : ExtendableEvent {
-  readonly attribute ShareData data;
-
-  void reject(DOMException error);
-};
-
-dictionary ShareData {
-  DOMString? title;
-  DOMString? text;
-  DOMString? url;
-};
-```
-
-The `onshare` handler (with corresponding event type `"share"`) takes a
-`ShareEvent`. The `data` field provides data from the sending application.
-
-How the handler deals with the data object is at the handler's discretion, and
-will generally depend on the type of app. Here are some suggestions:
-
-* An email client might draft a new email, using `title` as the subject of an
-  email, with `text` and `url` concatenated together as the body.
-* A social networking app might draft a new post, ignoring `title`, using `text`
-  as the body of the message and adding `url` as a link. If `text` is missing,
-  it might use `url` in the body as well. If `url` is missing, it might scan
-  `text` looking for a URL and add that as a link.
-* A text messaging app might draft a new message, ignoring `title` and using
-  `text` and `url` concatenated together. It might truncate the text or replace
-  `url` with a short link to fit into the message size.
-
-A share fails if:
-
-* The handler had no registered service worker.
-* There was an error during service worker initialization.
-* There is no event handler for `share` events.
-* The event handler explicitly calls the event's `reject` method (either in the
-  event handler, or in the promise passed to the event's
-  [`waitUntil`](https://www.w3.org/TR/service-workers/#wait-until-method)
-  method).
-* The promise passed to `waitUntil` is rejected.
-
-Once the event completes without failing, the share automatically succeeds, and
-the requester's promise is resolved. The end of the event's lifetime marks the
-end of the share, and there is no further communication in either direction.
-
-The Share Target API is defined entirely within the service worker. If the
-handler needs to provide UI (which should be the common case), the service
-worker must create a foreground page and send the appropriate data between the
-worker and foreground page, out of band. The `share` event handler is [allowed
-to show a
-popup](https://html.spec.whatwg.org/multipage/browsers.html#allowed-to-show-a-popup),
-which means it can call the
-[`clients.openWindow`](https://www.w3.org/TR/service-workers/#clients-openwindow-method)
-method.
-
-## Where do shares come from?
-
-Share events can be sent from a variety of places:
-
-* Built-in trigger (e.g., user picks "Share" from a browser's menu, to share the
-  URL in the address bar).
-* A native application.
-* A web application using the [Web Share
-  API](https://github.com/mgiuca/web-share).
-
-There will usually be a picker that lets the user select a target app. This
-could be the native system app picker, or a user-agent-supplied picker. The apps
-could include other system apps and actions alongside the web app handlers.
-
-If an event comes from a web app, the `data` field of the event should be a
-clone of the `data` parameter to `navigator.share`. If the event comes from some
-other source, the user agent may construct the `data` object as appropriate.
+See [Specification](https://wicg.github.io/web-share-target/).