KasperskyOS Community Edition 1.0

mqtt_subscriber example

Example use of the MQTT protocol in KasperskyOS.

In this example, an MQTT publisher must be started on the host operating system, and an MQTT subscriber must be started on KasperskyOS. The Subscriber entity is an implementation of an MQTT subscriber.

When the example starts and runs successfully, an MQTT subscriber started on KasperskyOS prints a "Got message with topic: my/awesome/topic, payload: hello" message.

The example also demonstrates the use of various virtual file systems (VFS) in a single solution. The example uses different VFS to access the functions for working with the file system and functions for working with the network:

• VfsNet is used for working with the network.
• VfsRamfs and VfsSdCardFs are used for working with the file system.

The Env entity is used to pass environment variables and main function arguments to other entities.

The CMake system, which is included with KasperskyOS Community Edition, is used to build and run the example.

Starting Mosquitto

To run this example, a Mosquitto MQTT broker must be installed and started on the host system. To install and start Mosquitto, run the following commands:

To start an MQTT publisher on the host system, run the following command:

Supplied resources

The following configuration files are included in the example:

• ./resources/include/config.h.in contains a description of the backend file system that will be used in the solution: sdcard or ramfs.

  Each backend in the solution also uses a separate VFS: respectively VfsSdCardFs or VfsRamfs.

• The ./resources/ramfs/etc and /resources/sdcard/etc directories contain configuration files for the VFS and Ntpd entities.

Example files

The code of the example and build scripts are available at the following path:

Building and running example

To run an example on QEMU, go to the directory containing the example, build the example and run the following commands:

See also Building and running examples section.