This topic describes how to manage data (read/write/execute) for cloud sevices like AirVantage.

Legato provides easy LWM2M connectivity to AirVantage through a .cdef file assets section using pre-built APIs.

AirVantage APIs

Use the AirVantage Connector API to configure your AirVantage connectivity to handle app updates.

Use the AirVantage Data API to setup your AirVantage data including read (variable), write (settings), and commands (executables).

.cdef Assets

You add an assets' section to your app's component definition file (.cdef) customizing AirVantage data including associating data types, setting default values, and executing commands using the pre-built AirVantage Data APIs.

Enable Observe

The LWM2M Observe feature is now supported by Legato. Observe provides a method to notify the server when there are changes to an asset. Read requests can also be initiated on an asset that is observed.

You have to enable LWM2M Observe in the AirVantage device app model first by adding the following value to the app model:

<dm>
    <action impl="LWM2M_OBSERVE"/>
</dm>

This will cause the server to enable Observe for all user-defined assets of all apps on the device as well as on LWM2M objects /4 /5 /9 /1024.

For detailed info on the LWM2M Observe specification, see the OMA-TS-LightweightM2M-V1_0-20160407-C.pdf, Section 5.5.

Once Observe is enabled, the following sequence happens between target device and server:

• server requests Observe on an asset
• device agrees and sends Observe response
• device sends notification (automatically when app changes any asset using one of these functions:
  • le_avdata_SetString()
  • le_avdata_SetBinary()
  • le_avdata_SetBool()
  • le_avdata_SetFloat()
  • le_avdata_SetInt().

Currently, the advanced features for Observe are not supported. This includes attributes such as minimum and maximum reporting times. Notifications are sent as soon as one of the listed functions are called.

Read Asset

There are several ways to read an asset's data from AirVantage:

• a simple read operation can be initiated from the server.
• if the app has registered a read callback on a variable field, the server can cause the field value to be sampled by reading this variable field.
• enable LWM2M_OBSERVE on the server and any changes to the asset will be pushed to the server by the device.

Copyright (C) Sierra Wireless Inc. Use of this work is subject to license.