Device Shadow

Github Repo	C Header	C source	JS source
mongoose-os-libs/shadow	mgos_shadow.h		api_shadow.js

Overview

This library provides a device shadow interface to manage device metadata on the cloud.

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Cross-cloud device cloud state API.

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MGOS_EVENT_BASE

#define MGOS_SHADOW_BASE MGOS_EVENT_BASE('S', 'D', 'W')

__cplusplus

mgos_shadow_event_name

const char *mgos_shadow_event_name(int ev);

Stringify shadow event name

mgos_shadow_get

bool mgos_shadow_get(void);

Request shadow state. Response will arrive via GET_ACCEPTED topic. Note that MGOS automatically does this on every (re)connect if device.shadow.get_on_connect is true (default).

mgos_shadow_updatef

bool mgos_shadow_updatef(uint64_t version, const char *state_jsonf, ...);

Send an update. Format string should define the value of the "state" key, i.e. it should be an object with an update to the reported state, e.g.: mgos_shadow_updatef("{foo: %d, bar: %d}", foo, bar). Response will arrive via UPDATE_ACCEPTED or REJECTED topic. If you want the update to be aplied only if a particular version is current, specify the version. Otherwise set it to 0 to apply to any version.

mgos_shadow_update

bool mgos_shadow_update(double version, const char *state_json);

"Simple" version of mgos_shadow_updatef, primarily for FFI.

JS API

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Shadow.addHandler

Shadow.addHandler(callback)

Set up shadow event handler. Callback receives event, obj parameters. Possibble values for event are: CONNECTED, UPDATE_ACCEPTED, UPDATE_REJECTED,UPDATE_DELTA. obj is an shadow object, valid for UPDATE_DELTA and UPDATE_ACCEPTED events. See https://github.com/mongoose-os-apps/example-shadow-js for the idiomatic usage.

Shadow.get

Shadow.get()

Ask cloud for the shadow. The reply will come as either GET_ACCEPTED event or GET_REJECTED event.

Shadow.update

Shadow.update()

Send shadow update. The idiomatic way of using shadow is: a) catch CONNECTED event and report the current state, and b) catch UPDATE_DELTA event, apply the delta, and report the state. Example:

Shadow.update(0, {temperature: 12.34});

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