WebIntents/Intents for multiple services
From W3C Wiki
In some kinds of applications the user will expect to bind multiple services for a given intent request. An example is where an application displays the temperatures of different rooms in a building. Another is where an application displays live thumbnails for multiple webcams.
This raises a number of challenges. How to present the registered matching services to the user for selection? The list could be very long, or the users may prefer a graphical selection mechanism. How to enable the user to search for additional matching services? How can the application pass context information to make the search more effective (e.g. temperature sensors in this building, not anywhere on the Internet). The need for applications to be able to access metadata for services (an identifier for the room that the temperature sensor is in, or the name of the location of the webcam).
One potential avenue for search is to consider that as a service in its own right and with its own intent. This shifts the burden from the web run-time, but you still want a way to pass the context. The search service would also be responsible for keeping the application and services at arms length (the very point of the Web Intents model).
A further consideration is where an application wants to show a dynamic depiction of a set of services where the services may appear and disappear. A classic example is the list of my friends who are currently online, as shown in a chat service. This could be presented graphically by an application with a map of my home town showing the current location of my friends (when they choose to share their location with me). This would seem to correspond to an intent for a presence service with location as part of the service metadata.