WebAPI/Inter App Communication Alt proposal: Difference between revisions

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WebAPI/Inter App Communication Alt proposal (view source)

Revision as of 07:11, 22 July 2013

1,353 bytes added ,  22 July 2013
→‎Usage examples
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== Lockscreen and Music ==
== Lockscreen and Music ==


(Disclaimer: this is just a rough example of a possible solution for this use case. This can probably be done with an unique keyword, different access rules and an agreed bidirectional API, but I wanted a wider example)
(Disclaimer: this is just a rough example of a possible solution for this use case. The permission model does not need to meet the real requirements for these apps. Also this use cases can probably be done with an unique keyword, different access rules and an agreed bidirectional API, but I just wanted a wider example)


The lockscreen wants to be able to:  
The lockscreen (Gaia System app) wants to be able to:  
* control the music played by the Gaia Music app
* control the music played by the Gaia Music app
* display information about the currently played track from the Gaia Music app or any other 3rd party music privileged app.
* display information about the currently played track from the Gaia Music app or any other 3rd party music app installed from the Firefox Marketplace.


In order to receive information about the currently played music track, the System app needs to add the following 'connections' field to its manifest
In order to receive information about the currently played music track, the System app needs to add the following 'connections' field to its manifest
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       'musictrack': {
       'musictrack': {
         'handler_path': 'musicmanager.html',
         'handler_path': 'musicmanager.html',
         'description': 'Show the currently played music track information in the lockscreen'
         'description': 'Show the currently played music track information in the lockscreen',
        'rules': {
          'installOrigin': ['marketplace.firefox.com']
        }
       }
       }
     }
     }
  }
  }


where it advertises itself as able to receive connections through the 'musictrack' keyword, requested by (at least) privileged apps and handled within the ''musicmanager.html'' page.
where it advertises itself as able to receive connections through the 'musictrack' keyword, requested by apps installed from the Firefox Marketplace and handled within the ''musicmanager.html'' page.


On the other side, music apps (lets say the Gaia Music app and a fictitious Songbirdy privileged app installed from the Firefox Marketplace and an also fictitious iTunos unprivileged app installed from an unknown source) that wants to be controlled from the lockscreen should add the following 'connect' field to its manifest:
On the other side, the Gaia Music app that wants to be controlled from the lockscreen (and only from there) should add the following 'connect' field to its manifest:
   {
   {
     'name': 'Music', (or Songbirdy or iTunos)   
     'name': 'Music',
     /* ... */
     /* ... */
     'connections': {
     'connections': {
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         'description': 'Play, pause and stop music tracks',
         'description': 'Play, pause and stop music tracks',
         'rules': {
         'rules': {
          'origin': ['system.gaiamobile.org']
        }
      }
    }
  }
We also have a fictitious ''Songbirdy'' privileged app installed from the Firefox Marketplace and an also fictitious ''iTunos'' unprivileged app installed from an unknown source that want to be controlled by any privileged app.
  {
    'name': 'Songbirdy', (or iTunos)
    /* ... */
    'connections': {
      'musicremotecontrol': {
        'description': 'Play, pause and stop music tracks',
        'rules': {
          'minimumAccessLevel': 'privileged'
         }
         }
       }
       }
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=== Current track showed in the lockscreen ===
=== Current track showed in the lockscreen ===


The Gaia Music app starts playing a random track and wants to share the information about this track with other apps. Since the shared information is harmless, it doesn't care about the receiver, so no rules are required while requesting the connection.
Gaia Music starts playing a random track and wants to share the information about this track with other apps. Since the shared information is harmless, it doesn't care about the receiver, so no rules are required while requesting the connection.


  connect('musictrack').then(function onConnectionAccepted(ports) {
  connect('musictrack').then(function onConnectionAccepted(ports) {
   // If the connection is allowed at least by one peer, the resolved callback
   // If the connection is allowed at least by one peer, the resolved callback
   // will be triggered with a list of MessagePorts as parameter (ports in this case).
   // will be triggered with a list of MessagePorts as parameter (ports in this case).
  // At this point the Gaia Music app can start sending information about
  // the currently played track.
   ports.forEach(function(port) {
   ports.forEach(function(port) {
     port.postMessage({
     // We still need to wait for the connected peer to notify as able to start
      title: 'The Beatles',
    // receiving messages through the port.
      artist: 'Strawberry fields forever'
    port.onstart(function() {
      // At this point the Gaia Music app can start sending information about
      // the currently played track.
      port.postMessage({
        title: 'The Beatles',
        artist: 'Strawberry fields forever'
      });
      // In this example approach, we probably don't need a bidirectional communication
      // as we have that through a different keyword, but we can always set a message
      // handler via MessagePort.onmessage at this point to handle the messages sent from
      // the peer on the other side of the port.
      port.onmessage = myMessageHandler;   
     });
     });
    // In this example approach, we probably don't need a bidirectional communication
    // as we have that through a different keyword, but we can always set a message
    // handler via MessagePort.onmessage at this point to handle the messages sent from
    // the peer on the other side of the port.
    port.onmessage = myMessageHandler;   
   });
   });
  }, function onConnectionRejected(reason) {
  }, function onConnectionRejected(reason) {
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  });
  });


Assuming that the lockscreen is the only application advertising itself as able to connect through the 'musictrack' keyword and there is no record of a previously allowed connection between this two apps through this keyword, a popup will be shown to the user saying something like:
The System app only allows connections with apps installed from the Firefox Marketplace (or from certified apps). In this case, the caller (Gaia Music app) is a certified app, so the connection request is allowed by the platform. Assuming that the lockscreen (System app) is the only application advertising itself as able to connect through the 'musictrack' keyword and there is no record of a previously allowed connection between this two apps through this keyword, a popup will be shown to the user saying something like:


  Do you want to allow ''Music'' to connect with ''System'' to ''Show the currently played music track information in the lockscreen''? [Allow|Deny]
  Do you want to allow ''Music'' (music.gaiamobile.org) to connect with ''System'' (system.gaiamobile.org) to ''Show the currently played music track information in the lockscreen''? [Allow|Deny]


In case that there would be more than one app subscribed to the 'musictrack' keyword, a different UI with a list of these apps would have been shown.
In case that there would be more than one app subscribed to the 'musictrack' keyword, a different UI with a list of these apps would have been shown.
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There is no need to show this UI again unless a new app subscribing to 'musictrack' is installed.
There is no need to show this UI again unless a new app subscribing to 'musictrack' is installed.


The user allows the connection and a system message is sent to the lockscreen. The lockscreen only allows connections with privileged apps, so it checks that in the connection request handler, and set a handler for the messages sent through the MessagePort via ''MessagePort.onmessage''
The user allows the connection and a system message is sent to the lockscreen (System app).


  navigator.setMessageHandler('connection', function(connectionRequest) {
  navigator.setMessageHandler('connection', function(connectionRequest) {
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     return;
     return;
   }
   }
 
 
   if (connectionRequest.callerInfo.accessLevel === 'certified' ||
   let port = connectionRequest.port;
      connectionRequest.callerInfo.accessLevel === 'privileged') {
  port.onmessage = onMusicTrackHandler;
    connectionRequest.port.onmessage = onMusicTrackHandler;
   port.start();
   } else {
    connectionRequest.reject();
  }
  });
  });


A similar connection request coming from Sonbirdy would also be accepted, cause we said that this app is privileged. However a connection request coming from iTunos would be rejected, since this app is unprivileged web content.
A similar connection request coming from Sonbirdy would also be allowed by the platform, cause we said that this app was installed from the Firefox Marketplace. However a connection request coming from iTunos would be rejected by the platform, since this app is unprivileged web content installed from an unknown source non listed within the lockscreen app rules. This request will not trigger any system messages and so the receiver won't ever be awake because of it (in this case the receiver (System app) is already live though).


=== Music controls in the lockscreen ===
=== Music controls in the lockscreen ===


The Lockscreen, in this example, wants to control '''only''' the music from the Gaia Music app (certified and with a known origin). Once the lockscreen is ready it sends a connection request of this kind:
The lockscreen, in this example, wants to control '''only''' (no reasons, just an example) the music from the Gaia Music app (known origin). Once the lockscreen is ready, it sends a connection request of this kind:


  connect('musicremotecontrol').then((function onConnectionAccepted(ports) {
  connect('musicremotecontrol').then((function onConnectionAccepted(ports) {
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     return;
     return;
    }
    }
 
 
   let musicPort = ports[0];
   let musicPort = ports[0];
   this.madeUpPlayButton.onclick = function() {
   musicPort.onstart(function() {
    musicPort.postMessage({
    this.enableControlButtons();
      action: 'play'
    this.madeUpPlayButton.onclick = function() {
    });
      musicPort.postMessage({
  };
        action: 'play'
  this.madeUpPauseButton.onclick = function() {
      });
    musicPort.postMessage({
    };
      action: 'pause'
    this.madeUpPauseButton.onclick = function() {
    });
      musicPort.postMessage({
  };
        action: 'pause'
  this.madeUpStopButton.onclick = function () {
      });
    musicPort.postMessage({
    };
      action: 'stop'
    this.madeUpStopButton.onclick = function () {
     });
      musicPort.postMessage({
   };
        action: 'stop'
      });
     };
  });
  musicPort.onstop(function() {
    this.disableControlButtons();
   });
  }, function onConnectionRejected(reason) {
  }, function onConnectionRejected(reason) {
   ...
   ...
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  }).bind(this));
  }).bind(this));


If no previous connection through the 'musicremotecontrol' keyword between the Lockscreen and the Gaia Music app has been previously allowed an UI is shown to the user with a message like:
If no previous connection through the 'musicremotecontrol' keyword between the lockscreen and the Gaia Music app has been previously allowed an UI is shown to the user with a message like:


'Do you want to allow System to communicate with Music to Play, pause and stop music tracks? [Accept|Reject]'
'Do you want to allow ''System'' (system.gaiamobile.org) to communicate with ''Music'' (music.gaiamobile.org) to ''Play, pause and stop music tracks''? [Accept|Reject]'


Even if Songbirdy and iTunos advertise themselves as able to connect through the 'musicremotecontrol' keyword, as the request is done with a specific rule that requires the receiver to have the 'music.gaiamobile.org' origin, these apps won't be listed in the above UI and won't receive any connection request.
Even if ''Songbirdy'' and ''iTunos'' advertise themselves as able to connect through the 'musicremotecontrol' keyword, as the request is done with a specific rule that requires the receiver to have the 'music.gaiamobile.org' origin, these apps won't be listed in the above UI and won't receive any system message with a connection request.


The user allows that connection and a system message is sent to the Music app. This app only wants to be controlled only by certified apps, so it checks for this kind of applications.
The user allows that connection and a system message is sent to the Music app.


  navigator.setMessageHandler('connection', function(connectionRequest) {
  navigator.setMessageHandler('connection', function(connectionRequest) {
   if (connectionRequest.keyword !== 'musicremotecontrol') {
  let keyword = connectionRequest.keyword;
   if (keyword != 'musictrack' ||
      keyword != 'musicremotecontrol') {
     return;
     return;
   }
   }
    
    
   if (connectionRequest.callerInfo.accessLevel === 'certified') {
   let port = connectionRequest.port; 
     connectionRequest.port.onmessage = onMusicRemoteControlHandler;
  switch(keyword) {  
  } else {
     case 'musictrack':
     connectionRequest.reject();
      port.onmessage = this.onMusicTrackHandler;
      break;
     case 'musicremotecontrol':
      port.onmessage = this.onMusicRemoteControlHandler;
      break;
   }
   }
  port.start();
  });
  });


Ferjm
Confirmed users
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Retrieved from "https://wiki.mozilla.org/Special:MobileDiff/682072"

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