Components Overview¶
A board farm set up with not-my-board consists of multiple components:
Place: The physical embedded hardware setup.
Hub: A single instance, that schedules access to Places.
Exporter: This runs on the host, where the Place is connected. It registers the Place with the Hub.
Agent: A board farm user runs this on their host. It requests a Place from the Hub, connects directly to the Exporter and tunnels resources from the Exporter to the host of the user.
Client: The CLI, that controls the Agent.
Place¶
A Place is not only an embedded board, but it includes all the equipment required to develop on that board, too. Equipment can be for example a controllable power supply, a wireless access point or a camera. Of course it’s not even limited to a single board: It can be a system consisting of multiple connected boards. Every board or equipment is called a Part.
Hub¶
The Hub provides its interface over HTTP(S) and WebSocket. Exporter and Agent stay registered as long as the WebSocket connection is alive. If the Exporter connection breaks, then the Place will no longer be scheduled. If the Agent connection breaks, then the user loses access and the Place can be reserved by another user.
The Hub only provides a list of known Places with their description. The Agent then filters the list and asks the Hub to reserve one of all the possible candidate Places. As soon as one of the candidates is free, the Hub let’s both Exporter and Agent know about the new reservation.
Exporter¶
The Exporter opens a WebSocket connection to the Hub and exports the resources as an HTTP proxy. By not exporting the ports directly, only the HTTP proxy port needs to be opened in the firewall and the Exporter can authenticate the user before granting access.
Resources can be exported as a TCP port (like the SCPI interface of a power supply), or over USB/IP, like the USB port of the board or the USB to serial converter.
The proxy uses IP-based authentication to avoid the TLS overhead. Once the Place of the Exporter is reserved, the Hub tells the Exporter which IP address to allow access.
The exporter assigns specific tags to the exported parts of the place. Those tags describe to what the parts are compatible with. An Agent can then filter based on those tags.
Agent¶
The Agent is a long running process on the host of the user, to keep the connection to the Hub open and to tunnel the resources from the Exporter. It listens on a Unix domain socket for commands from the Client.
The Client provides an import description of the Place it wants, i.e. which
parts it needs (identified by the compatible tags) and where to attach those
parts. For example: I need a “Raspberry Pi” and want its USB serial adapter
attached to USB port 3-4 and its USB port to 3-5. The Agent then filters
all the exported Places based on that description and gives the Hub a list
of the matching candidates. As soon as the Hub reserves one of the candidates,
the Agent connects directly with the Exporter and attaches the resources as
requested.
Client¶
The Client is everything that isn’t a long running background process. For
example the not-my-board attach command acts as a Client: It connects to the
Agent UNIX domain socket, request a new Place to be attached and then exits
again. Those are the commands, that users would run during their day-to-day
development work.