GEM “Headless Devices”

Last month’s DVB Steering Board meeting approved a new GEM specification titled “Application Gateway and Media Server Fragment”. This specification is now available for download as DVB BlueBook A127 from the page Other MHP/GEM Specifications.

One possible deployment scenario for Java based procedural application environments is devices such as gateways or routers. These don’t normally include a display or any user input capability. Devices like these are called “headless” in Java – a historical term dating back to Unix workstations. Some example applications which can be deployed in such headless devices could include the following:

  1. EPG generating an HTML user interface (UI) to devices using DLNA remote UI or similar,
  2. Application supporting proxying of signalling protocols when client and server are not in the same IP domain,
  3. Support for proprietary or non-standard content download protocols (where the headless device has content storage capabilities),
  4. Operator provided non-TV services like collecting alarms from home devices.

By defining a subset of GEM-IPTV for headless devices, the new document enables headless applications to be efficiently supported on a mixed deployment of headless devices and conventional set-top boxes. In the absence of such a subset, the options for a mixed deployment of headless devices and set-top boxes would be less efficient ones such as:

  1. Deploy different software environments for headless devices and set-top boxes with different versions of each application,
  2. Support two software environments on set-top boxes, namely GEM-IPTV and a second software environment for headless devices.

The fact that a device does not include a display or any user input capability does not exclude it from handling A/V media. The most obvious example is a headless device which includes media storage and can offer content to devices across a home network. Headless devices without media storage could perhaps act as a proxy, initiating A/V media delivery from the network and relaying the content across a home network using home networking protocols. Both of these examples can be addressed by the new specification. However, one type of headless device is out of scope of this document: these are devices which can support the full GEM user interface API using a remote UI protocol. Such devices should be able to support the full GEM-IPTV specification.