Grass Valley K2 Edge Protocol Manual v1.0 - Manual (Page 21)

K2 Edge Protocol Manual – document version 1.0 – Page 21
5. K2 Edge API NRE Feedback
5.1. Introduction
The K2 Edge API NRE commands support a dedicated feedback protocol that has following distinctive
features:
• NRE commands allow the preloading and playing of templates. A single template can depend on
the presence of several assets.
• The NRE feedback protocol provides feedback for each of these assets in error situations.
• The NRE feedback protocol is based on the life cycle of a template. Many templates, once
started, never end unless they are stopped by other templates. The protocol provides feedback
on both the moment a template enters its endless running state, as well as on the point it has
finished.
• The NRE feedback protocol allows for various levels of feedback detail.
5.2. Supported commands
The following NRE sub commands support the feedback protocol described here:
• preload-play
• preload
• play
• object-info
5.3. Asynchronous nature
The K2 Edge API protocol - used for both commands and feedback messages - is asynchronous in
nature. This means that:
• Incoming commands are not guaranteed to be processed in order of reception.
• Outgoing feedback is not guaranteed to be sent in the order commands came in.
• Several commands can be sent in succession, before the first feedback from nexos has been
received.
• The parallel nature of nexos will allow it to process several commands simultaneously, and as a
result return feedback on all of these commands simultaneously.
5.4. The exid field
The exid field in the NRE sub commands is a mandatory field, reserved to define an external ID. This ID
enables linking feedback to commands. A unique exid value must be defined (for example an
incrementing serial number) for each command sent to nexos. The exid field value makes it is easy to
link feedback to commands. This is especially useful when nexos is working on several commands
simultaneously. The exid field and value will always be returned in the feedback, unmodified.
5.5. Life cycle points and events
When nexos is instructed to preload and/or play an instance of a template (through one of the supported
commands), the instance is going through a life cycle. This cycle begins when the command is received
and ends when the template instance is finally stopped.