Yes, you are right. When web app's activity is paused, currently the js timer is stopped, which makes it not able to send out notification. From use case perspective, notification is very closely related to app life cycle, especially background page(service like) support. But the implementation is independent however.
Thanks, Shiliu. From: Zhu, Yongsheng Sent: Wednesday, December 25, 2013 4:01 PM To: Min, Hongbo; Wang, Shiliu; 'crosswalk-dev@lists.crosswalk-project.org' Cc: Christiansen, Kenneth R Subject: RE: Intent to implement - [Android] Standard Web notification API for xwalk. Thanks, Shiliu and Hongbo. The most important use case is that web apps can send notification messages after it's in background. It's a very common case, I think. Currently if a web app is paused, it seems it may not do anything including sending notification messages? This is what we need to consider together with app life cycle. Yongsheng From: Crosswalk-dev [mailto:crosswalk-dev-boun...@lists.crosswalk-project.org] On Behalf Of Min, Hongbo Sent: Wednesday, December 25, 2013 10:34 AM To: Wang, Shiliu; 'crosswalk-dev@lists.crosswalk-project.org' Cc: Christiansen, Kenneth R Subject: Re: [Crosswalk-dev] Intent to implement - [Android] Standard Web notification API for xwalk. A very elaborate write-up! The notification would not be fired if the web app is in background, e.g. after home button is pressed, right? I assume yes since once the app is switched to background, it is in paused status. From: Crosswalk-dev [mailto:crosswalk-dev-boun...@lists.crosswalk-project.org] On Behalf Of Wang, Shiliu Sent: Tuesday, December 24, 2013 2:04 PM To: 'crosswalk-dev@lists.crosswalk-project.org' Cc: Christiansen, Kenneth R Subject: [Crosswalk-dev] Intent to implement - [Android] Standard Web notification API for xwalk. Description: Web notification api is missed in xwalk. The spec is defined at http://www.w3.org/TR/notifications/ . It's for web app to be able to create an OS level notification, which will bring the app back to front when being clicked. On Android, system notifications are the ones listed when pulling down the status bar. Chromium support both standard web notification and web notification with customized html layout. For xwalk on Android, will only implement standard web notification for first step. Affected component: 1. XWalk Runtime, for overwriting interface from content. 2. Android port, for implementing the notification. Related feature: (JIRA ID): https://crosswalk-project.org/jira/browse/XWALK-94 Target Release: (Crosswalk N): Crosswalk 4 Implementation details: 1. Content already exposes interface for web notification from blink. ContentBrowserClient for blink to browser(handling request for create/show notification) and RenderViewHost for browser to blink(trigger js callback when notification clicked/closed/shown). 2. The UI composition of web notification and android notification is quite match, they both contain title, message and icon. So the properties of web notification will be directly mapped to the relevant field for android notification. 3. Icon is a little bit more complicated, android notification accept a small icon and a big one, small icon will be used when the status bar is not expanded. And it must be a resource id, while big icon can be a bitmap. For web notification, icon is normally a url. So the small icon for android notification will be set to the application's icon regardless of the url specified in web notification. 4. For browser, web notification requires an explicit grant of permission. For webapp, it will be granted by default if the permission is declared in manifest. 5. Notification won't be gone even the application is closed or killed by android. 6. For android, the notification can carry two Pending Intent<http://developer.android.com/reference/android/app/PendingIntent.html>, one for clicked and the other for canceled. a. Clicking notification: i. If webapp is still alive, bring the app to front and invoke the onclick js callback. ii. If webapp is gone, recreate the webapp. It's impossible to invoke the js callback in this case. b. Canceling notification: i. If webapp is still alive, invoke the onclose js callback. (the callback will be executed after the webapp brought back to front, because when it's stopped, js timer is stopped.) ii. If webapp is gone, nothing else will happen. 7. To achieve above, a. The pending intent for clicking will be an activity intent with flag LAUNCH_FROM_HISTORY. For bring the app back to front, this is enough. To invoke the js callback, the embedder activity(including xwalkRuntimeActivityBase for runtime usage, CoreShellActivity, CordovaActivity) needs to override the onNewIntent() function and send the new intent to XWalkContentClientBridge, bridge will handle the new intent and invoke the correct callback through notification id. b. The pending intent for closing will be a broadcast intent. The broadcast receiver will be registered/unregistered dynamically regarding to the creation/deletion of web notification. When the webapp is killed, the broadcast receiver is gone too. It's to avoid starting any process when cancelling notification. 8. Android only keeps one PendingIntent for each kind system wide. The "kind" is determined by the class name, action and category. So here to make it possible to keep multiple notifications for one web app. The notification id will be used as category for the pending intents. 9. Upstream alignment: a. Chromium doesn't have implementation for web notification on android. Neither chrome nor chrome webview. As discussed with them, they want to propose to enhance the web notification spec to allow notification to carry meta data and specified URL. Which allows the page to be completely restored from the notification even it was gone. b. If we wait for upstream, it will be a long time. c. The idea of this intent is to spend minimum effort to implement the workable current version of web notification. Thanks, Shiliu.
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