Minimal User Interface (Rust)

The psibase library can provide a minimal UI to your services. This UI can help get you started developing your own services, but isn't suitable for end users.

example-ui

Run the following to create a project:

cargo new --lib example-ui
cd example-ui
cargo add psibase
cargo add -F derive serde

Replace the content of lib.rs with the following:

#[psibase::service]
#[allow(non_snake_case)]
mod service {
    use psibase::*;

    #[action]
    fn add(a: i32, b: i32) -> i32 {
        a + b
    }

    #[action]
    fn multiply(a: i32, b: i32) -> i32 {
        a * b
    }

    // This action serves HTTP requests
    #[action]
    fn serveSys(request: HttpRequest) -> Option<HttpReply> {
        // serve_simple_ui serves UI files to the browser and
        // provides an RPC interface for preparing transactions.
        // #[psibase::service] automatically generates Wrapper.
        serve_simple_ui::<Wrapper>(&request)
    }
}

Add the following to Cargo.toml.

[package.metadata.psibase]
package-name = "ExampleUI"
server = "example-ui"

The server option registers an RPC service to handle HTTP requests. In this simple case, example will handle its own requests. See the registerServer docs for more details.

Building and Deploying

This will build the service and deploy it to the chain:

cargo psibase install

Trying the UI

If you're running a test chain locally, then it will typically be at http://psibase.localhost:8080/. To try the service, prefix your host with your service name (e.g. http://example.psibase.localhost:8080/).

How it Works

• psinode forwards most http requests to the http-server service.
• http-server looks at the request domain. If it begins with the name of a registered service, it calls that service's serveSys action to process the request.
• psibase::serve_simple_ui handles the following requests:
  • GET / returns a minimal html file which loads the javascript to generate the UI.
  • GET /action_templates returns a template json structure (below). This lets the UI know which actions are available and sample values for their arguments. This isn't a schema; it's only suitable for simple cases.
  • POST /pack_action/add accepts the arguments for the add action as a JSON object, converts it to binary, and returns the result.

For more detail, see Web Services.

/action_templates result

{
  "add": {
    "a": 0,
    "b": 0
  },
  "multiply": {
    "a": 0,
    "b": 0
  },
  "serveSys": { ... }
}