libmist

Mist middleware library

Introduction

TODO intro to libmist.

Spontaneous events

Some data sampling and transmission activities are controlled by rules applied to a device, but others are transmitted as they occur - spontaneously. Spontaneous events may start from changes in the environment, but in some cases are also software generated. Spontaneous resource events are transmitted using broadcast and depending on the underlying network configuration, may be prioritized higher than other data.

Spontaneous event backoff configuration

In order to control the impact of high-priority spontaneous events, the middleware applies a default backoff scheme to all spontaneous resource events. The backoff time increases with subsequent events if at least 2 minutes have not passed between the events. The second event in a series is allowed after at least 10 seconds have passed, the third after another 30 have passed and so on. The default backoff values are: 0, 10, 30, 70, 120.

The backoff value can be adjusted for each spontaneous event source with the mist_configure_spontaneous_event_backoff(min, max, step) function.

The backoff value is calculated with the formula: backoff = MIN(MAX(step * ((1 << events) - 1), minimum), maximum) If more than 2 times the maximum time has passed since the last value, events is reset to 0. The smallest possible backoff_minimum value is 1, the default step value is 10, the default maximum value is 120.