Architecture: Parts, Sub-Parts, and Remotes

When smart machines communicate with each other, they can share resources and operate collaboratively. This document explains how to establish secure connections between machines.

Machine parts

Machines are organized into parts, where each part represents a computer (a single-board computer, desktop, laptop, or other computer) running viam-server, the hardware components attached to it, and any services or other resources running on it.

Every smart machine has a main part which is automatically created when you create the machine. Multi-part machines also have one or more sub-parts representing additional computers running viam-server.

There are two ways to link machine parts:

Connections between machines are established using the best network path available.

When you configure a remote or a sub-part, the main machine part can access all the components and services configured on the remote machine part as though they were entities of the main machine part. This is a one-way connection: the main machine part can access the resources of the remote machine part, but the remote machine cannot access the resources of the machine part remoting into it.

Example of a remote and a two part machine where the main (and only) part of machine 1 remotes into the main part of machine 2, and thus has access to all resources of machine 2.

Configuration

Configure a sub-part

You can make a multi-part machine by first configuring one part which is the “main” part, and then configuring one or more sub-parts. The main part will be able to access the resources of its sub-parts. Sub-parts will not have access to the resources of the main part.

Use the parts dropdown menu in the top banner of your machine’s page on the Viam app to add a new sub-part:

The Viam app interface with the part dropdown open. A new part called ‘my-sub-part’ is being created.

To delete a sub-part or make it the main part, use the buttons in the top right of the Config tab.

The config tab of a machine’s page noting the location of the Make main part and Delete Part buttons.

Configure a remote

To establish a connection between a part of one machine and a part of a second machine, configure a remote on the first machine’s part.

  1. Go to the Viam app machine page of the smart machine part to which you wish to establish the remote connection. This is the machine part whose resources will be accessible to the other machine part.

  2. Click the Code sample tab.

  3. On the Language toggle, select Remotes, then click Copy.

  4. Go to the Viam app machine page of the machine part from which you want to establish a remote connection. This is the machine part that will be able to access the resources of the other machine part.

  5. Click the Config tab, click the Remotes subtab, and select JSON mode.

    The Viam app CONFIG tab with the REMOTES subtab open and JSON mode selected.

  6. Click Create Remote.

  7. Paste the remote config you copied in step 4 into the empty field.

  8. Click Save Config in the bottom left of the screen.

Using remote parts and sub-parts with the Viam SDKs

Once your sub-part or remote part is configured, you can access all the components and services configured on the sub-part or remote machine part as though they were resources of your main machine part. The only difference is that the names of the components have the remote machine part name prepended to them. For example, instead of calling

servo = Servo.from_robot(robot=robot, name='my_servo')

you need to call

servo = Servo.from_robot(robot=robot, name='my-sub-part-name:my_servo')
servo = Servo.from_robot(robot=robot, name='my-other-robot-main:my_servo')

For an example that controls a motor that is a component of a sub-part, see the Mock Robot tutorial.



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