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Usage

Window Configuration​

Prior to the start of a payload window, the satellite bus will boot up the payload and place on it's file system a window configuration JSON file containing configuration for the upcoming payload window. This configuration includes information provided by the bus and any parameters defined during the creation of the window in the Tasking API.

Additionally there will be a version number included in the root dictionary. The current version is 1.

The filename is constructed using the window id and the json file extension. For example, for a window with id = 1304893, the window configuration file location would be /signaling/window_configs/1304893.json.

{
    "version": 1,
    "signal_parameters": {
        "lunch_money": 1.72,
        "greeting": "hello, world!",
        "tasking_parameters": {
            "key1": "some value",
            "Key2": "some other value"
        }
    }
}

On payload startup the satellite bus will place any files uploaded through the tasking API into the payload's inbox directory under the Tasking API user that has requested it.

For example if Tasking API user john requested an upload of file foo.sh the satellite bus will place the file on the payload at path /signaling/inbox/john/foo.sh.

Configure​

The payload will be switched on in advance of a scheduled window. Following payload startup the satellite bus will issue a configure signal, invoking payload_exec and supplying the -e argument.

The configure signal allows the payload to reconfigure itself based on the ID of the window. The payload may, for example, move any new uplinked files out of the inbox directory. As it will be invoked synchronously, the configure step should complete quickly, within 15 seconds or less.

Arguments​

-w - ID of upcoming window -u - ID of the user that created the window via the Tasking API

/usr/bin/payload_exec -u john -e -w 1304893 > /dev/null

Window Start​

At the start of a payload window (start_time, as defined by the Tasking API), the satellite bus will issue a window start signal, asynchronously.

Arguments​

-w - Window ID -t - Window end time in UNIX timestamp format -u - ID of the user that created the window via the Tasking API

nohup /usr/bin/payload_exec -u john -w 1304893 -t 1611718292 &> /dev/null &

Window End​

At the end of a window the satellite bus will issue a shutdown command to the payload. At some time after this command, power to the payload will be cut.

Error Handling​

The configure step may return a nonzero exit code, this will cause the whole window to be aborted. It may also output to stderr, but generally it should send log files through the OORT API. Ethernet will be switched on throughout the configure step.

The window start signal is issued asynchronously. Its exit code, stdout and stderr will not be captured. The payload_exec program is responsible for sending down any log files through the OORT API. Additionally, following the window start signal, ethernet for the payload may be shut down before the window completes.