Viam Rust SDK

(In)stability Notice

Warning This is an alpha release of the Viam Rust SDK. Stability is not guaranteed. Breaking changes are likely to occur, and occur often.

Prerequisites

Installing Rust for Mac and Unix-Like

Prior completing these steps make sure no other installations of Rust are present, for example for Mac you want to run brew uninstall rust

Next run the following command curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh in your favorite terminal, if you have installed rustup in the past you can just run rustup update. The PATH environment variable should be updated by the installer, running which rustc you should see something like ~/.cargo/bin/rustc if not you may need to reload your terminal and if it still doesn't work then you should add ~/.cargo/bin in your PATH environment variable (more info here)

Repository Layout

• proto All the google and viam api proto files
• src The implementation of the Rust sdk library
• examples A list of examples

Getting Started

First you may want to build the SDK library, to do so navigate to the root of the repository and run cargo build this should pull all the dependencies and hopefully build the library! You can locally build the library documentation by running cargo doc --open, it will open your browser pointing to the documentation Lastly you can run one of the examples by navigation to the examples folder and run cargo run --bin test-dial

Usage

To use the SDK and connect to an RDK server you will need to setup a couple of things.

Create a new project with Cargo

Outside of the SDK repository simply run cargo new my-robot this will create a new project named my-robot as well as a couple of files

Configure Cargo.toml

The details of Cargo.toml are beyond the scope of this README please refer to this for more info Add the following to your Cargo.toml :

[dependencies]
viam = {path = "../"} #this path should point to the Rust SDK repository
anyhow = { version = "1.0", features = ["backtrace"]}
tokio = { version = "1.0", features = [ "rt-multi-thread", "time", "fs", "macros", "net",] }
tonic = {version = "0.6.2",features = ["tls", "compression", "tls-roots"]}

Change main.rs

At the top of the file add :

use anyhow::Result;
use viam::gen::proto::api::robot::v1::{robot_service_client, ResourceNamesRequest};
use viam::rpc::dial;

Replace the main function signature with :

#[tokio::main]
async fn main() -> Result<()> {
    println!("Hello, world!");
}

Echo Streaming Example

The echo example communicates with the goutils sample server. It demonstrates individual, streamed, and bidirectional communication. To test, navigate to your goutils clone and run

go run rpc/examples/echo/server/cmd/main.go

Take note of the signaling port and replace the port value in examples/src/echo/main.rs with yours like this :

let c = dial::DialOptions::builder()
    .uri("localhost:<your-port>")
    .without_credentials()
    .allow_downgrade()
    .connect
    .await?;

Then, from the examples/ directory, run

cargo run --bin test-echo

Connecting to a robot

If you are connecting to a robot with authentication you will need to create credentials :

let creds = dial::CredentialsExt::new(
        String::from("robot-location-secret"),
        String::from("secret"),
    );

Then to obtain a channel do :

let c = dial::DialConfig::builder()
        .uri("test-main.33vvxnbbw9.local.viam.cloud:8080") // Robot address
        .with_credentials(creds) // credentials
        .connect()
        .await?; // if the connection complete you will have a channel otherwise an error

Now if we want to get the metadata of the robots we just have to do :

let mut service = robot_service_client::RobotServiceClient::new(c);
    let _rsp = service
        .resource_names(tonic::Request::new(ResourceNamesRequest {}))
        .await?;
    println!("Rsp {:?}", _rsp);

Note that after that the channel has been moved and therefore will not be usable again, to avoid this clone it first.

If you want to connect to a robot without credentials then just do :

let c = dial::DialConfig::builder()
        .uri("localhost:8080") 
        .without_credentials()
        .insecure() // you can also do allow_downgrade()
        .connect()
        .await?; // if the connection complete you will have a channel otherwise an error

Note also that this will attempt to connect over webRTC by default. To override and only use direct gRPC calls, add a disable_webrtc() call to your dial builder, like so:

let c = dial::DialConfig::builder()
        .uri("test-main.33vvxnbbw9.local.viam.cloud:8080") // Robot address
        .with_credentials(creds) // credentials
        .disable_webrtc() // forces gRPC connection
        .connect()
        .await?; // if the connection complete you will have a channel otherwise an error

Using FFI (Foreign Functions Interface)

The rust sdk exposes a few functions conforming to the platform's C calling convention. Most languages support calling C code but their particular implementation is beyond the scope of this README. However we provide example in C++.

Set up

For now we only support Unix-like systems. Before continuing make sure that GRPCCpp has been installed on your system. Navigate to :

cd examples/src/ffi/cpp
# Then
make buf

Echo example

The echo example communicate with the goutils sample server, navigate to your goutils clone and run

go run rpc/examples/echo/server/cmd/main.go

Then run

make ffi_echo && ./ffi_echo

Robot example

The robot example communicate with a rdk server Update the dial function with your address and secret in the file ffi_robot.cc

dial("<robot-address>",
            "<robot-secret>",
            false, ptr);

Then run

make ffi_robot && ./ffi_robot

Two Notes on Connectivity and webRTC Functionality

First: the rust SDK attempts to dial over webRTC by default. You can override this by calling disable_webrtc() on the dial builder.

Second: the rust webRTC implementation is still new, and liable to have bugs. At a minimum, we expect that calls to ShellService::shell() have a high likelihood of strange behavior. If you encounter any issues with streaming requests over webRTC, direct dial (by disabling webrtc as above) should resolve them. And please file a bug report! We will endeavor to be as responsive as possible, and resolve issues as quickly as possible.

License

Copyright 2021-2022 Viam Inc.

Apache 2.0 - See LICENSE file