Daemon

Table of Contents

• Zenoh-Flow Daemon Configuration File
• Setting the Zenoh-Flow Daemon UUID

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To start a Zenoh-Flow Daemon, at least a name must be given. This name is a human-readable chain of characters that is meant to facilitate interactions.

The command below starts a Zenoh-Flow Daemon named alice:

cargo run -p zfctl -- daemon start alice

It is also possible to pass this information through a configuration file that additionally allows specifying the path to extensions: shared libraries that enable executing nodes implemented in another programming langage than Rust (for instance, in Python).

Zenoh-Flow Daemon Configuration File

This file contains the following fields:

• a name: the name to associate to this daemon.
• (optional) extensions: the path where the daemon can find the extensions files.

name: zenoh-flow-daemon-0
extensions: /etc/zenoh-flow/extensions.d/

The Zenoh-Flow Daemon can then be launched using:

cargo run -p zfctl -- daemon start -c path/to/configuration.yaml

Setting the Zenoh-Flow Daemon UUID

As you may have noticed, launching for instance zfctl daemon list, each Zenoh-Flow Daemon is also attributed a unique identifier. In order to assign a Node to a Zenoh-Flow Daemon, this unique identifier must be specified in the mapping section of a data flow descriptor.

This identifier is equal to the Zenoh Identifier of the underlying Zenoh Session.

Hence to modify this value, a valid Zenoh configuration should be provided to zfctl using the -z option.

The following configuration sets the Zenoh Identifier of the Zenoh Session --- and, thus, of the Zenoh-Flow Daemon --- to 11111111111111111111111111111111.

{
  "id": "11111111111111111111111111111111",
}

cargo run -p zfctl -- -z path/to/zenoh_configuration.json daemon start alice

If we launch this command after, you will see this output:

cargo run -p zfctl -- daemon list

+----------------------------------+-------+
| Identifier                       | Name  |
+==========================================+
| 11111111111111111111111111111111 | alice |
+----------------------------------+-------+