chrome.mdns API

chrome/common/extensions/api/dial.idl

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Use the <code>chrome.dial</code> API to discover devices that support DIAL.
 // Protocol specification: http://www.dial-multiscreen.org/
 namespace dial {
 
   // Represents a unique device that responded to a DIAL discovery request.
   dictionary DialDevice {
@@ skipping 16 matching lines @@
     network_disconnected,
     cellular_network,
     socket_error,
     unknown
   };
 
   dictionary DialError {
     DialErrorCode code;
   };
 
+  // The NetworkService interface is used to provide a set of connection
+  // information for an HTTP service endpoint and if available, service events
+  // running on a networked device.
+  //
+  // TODO(justinlin): Add event interfaces?

[mark a. foltz, 2013/08/19 18:25:26]

Not sure if it make sense on an individual service object.   For example if you
add a listener to a service, and get an update event, would you then have to
unregister the listener on the old NS object and re-register it on the new
object?

The NSD spec has a NetworkServices object that has the event API for a given
services query, but even then that design has some issues.

+  dictionary NetworkService {
+    // A unique identifier for the given user-selected service instance.
+    DOMString id;
+
+    // The name of the user-selected service.
+    DOMString name;
+
+    // The valid service type token value of the user-selected service
+    // (i.e.  upnp:..., zeroconf:..., dial:...).
+    DOMString type;
+
+    // The control URL endpoint (including any required port information) of the
+    // user-selected control service that has been added to the entry script
+    // origin's URL whitelist.
+    DOMString url;
+
+    // The configuration information associated with the service depending on
+    // the requested service type.
+    DOMString config;
+
+    // Current date + deviice expiry in UTC time.
+    long expiryTimestamp;
+
+    // Whether the service is online.
+    boolean online;
+  };
+
   callback BooleanCallback = void (boolean result);
 
+  callback GetNetworkServicesCallback = void (NetworkService[] deviceInfo);

[mark a. foltz, 2013/08/19 18:25:26]

s/deviceInfo/networkServices/

+
   interface Functions {
-
     // Requests that DIAL discovery happen immediately.  The request may not be
     // honored as discovery may already be happening in the background.  The
     // callback is invoked with |true| if discovery was initiated or |false|
     // otherwise.
     static void discoverNow(BooleanCallback callback);
+
+    static void getNetworkServices(GetNetworkServicesCallback callback);

[mark a. foltz, 2013/08/19 18:25:26]

There should be a query parameter to indicate the kind of service being queried
for, for example zeroconf:googlecast_.tcp_.  I don't think we want to include
all services by default.

   };
 
   interface Events {

[mark a. foltz, 2013/08/19 18:25:26]

It makes more sense to add an event here to fire when a previously-returned
NetworkService has changed. The event listener API could take the same service
type parameter as getNetworkServices(); is that possible in the extensions API
framework?

If not, we'll have to keep track of which service(s) will fire events.  Will
calling GetNetworkServices once for a service type register it?  I feel like
that's a weird coupling between the two APIs, although my patch has the same
problem.

Let's discuss more.

 
     // Event fired to inform clients of the current, complete set of responsive
     // devices.  Clients should only need to store the list from the most recent
     // event.  May be fired in response to multiple circumstances:
     //
     // (1) The DIAL service refreshed its device list through periodic polling.
     // (2) A client invoked discoverNow().
     // (3) An event happened that should invalidate the device list
     //     (e.g., a network interface went offline), in which case it is fired
     //     with an empty array.
     static void onDeviceList(DialDevice[] result);
 
     // Event fired to inform clients on errors during device discovery.
     static void onError(DialError error);
   };
 };