UrbitGrants

%lick

Completed
Proposal
Core Dev

ID

P0244

Date

February 23, 2023

Champion

~lagrev-nocfep, ~rovnys-ricfer

Grantee(s)

~mopfel-winrux

Introduction

This is a grant for a new vane called %lick. This will act as a way for Gall agents to open and close a communication port to Earth processes; enabling communication with various devices and processes ranging from cryptographic hardware keys and dongles, embedded devices speaking on common communication interfaces (UART, SPI, I2C, etc), and IoT connected devices.

How %lick will work is best explained with the following usecase:

I have a receipt printer that communicates through UART communication. I want it to print out any %rumors I recieve.

This usecase will act as an end to end test of the entire system (described below) and allow incremental experimentation until the final product.

This grant is split into 4 parts

  1. Creation of the vane (%lick and lick.c)
  2. Gall agent (%receipt)
  3. Earth process which communicates with lick's port and the receipt printer
  4. Documentation and Tutorial

Vane

The Arvo vane exposes an interface for opening and communicating with a host device through Unix IPC ports. %lick extends %galls pokes to Earth based processes.

An agent will be able to %spin up a port (type path) and vere will create it in the piers .urb/dev folder. An agent will also be able to %shut this port. When an Earth process connects to the IPC port vere will send a %soak to the duct that opened the port. The soak will have the mark %connect. When the Earth process disconnects vere will send a %soak with a %disconnect mark. Whenever an earth process is connected the gall agent will be able to %spit a noun with the structure [=mark =noun]. The gall agent should also be able to receive a %soak with a similar noun structure.

Data being transfered along the IPC port will be jammed nouns.

Gall Agent

Once the vane and library is tested work will begin on implementing a gall agent that subscribes to the %rumors app by ~paldev. The app will begin by %spining a port. When an earth process connects to the port it will subscribe to %rumors and on recieving one it will send the correct command for the printer to output it.

Earth Process

The Earth process will connect to a given IPC port and wait for a %print mark with a @ta. It will use vere's eval function to cue the noun from the port and parse the hoon pretty printer to correctly print the message.

This will be fine for a receipt printer but future work will have to be done to implement a noun library in a given language.

Documentation and Tutorial

Documentation of how the vane works is vital to the succuss of it. The benefit of having a working app alongside the vane is to show users how to use the vane. The resulting gall agent and earth process will be written into a tutorial that should allow anyone to replicate this work.

Milestones

Milestone 1: Vane

Payment: 3 Stars

This milestone includes a working vane that we can send nouns back and forth too.

Milestone 2: Gall Agent

Payment: 2 stars

This milestone is complete when a user can install %receipt and have it print rumors.

Milestone 3: Earth Process

Payment: 1 star

This milestone is complete when a user can install the app and have the printer print its rumors

Milestone 4: Documentation and Tutorial

Payment: 1 star

This milestone is complete with the delivery of a documentation and tutorial package.