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:
- EPG generating an HTML user interface (UI) to devices using DLNA remote UI or similar,
- Application supporting proxying of signalling protocols when client and server are not in the same IP domain,
- Support for proprietary or non-standard content download protocols (where the headless device has content storage capabilities),
- 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:
- Deploy different software environments for headless devices and set-top boxes with different versions of each application,
- 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.