HarmonyLang-Server

A server that hosts the (C)Harmony compiler implemented in C, a successor to the Harmony compiler implemented in Python.

Development Setup

Make sure you have Node installed. Clone the repository and run yarn install.

You can then start the server by running yarn dev.

Runbook

Monitoring

Realtime metrics are captured on PM2. Logging is being done on Firebase.

High CPU Usage

This can be deteted on the AWS monitor. Contact Anthony if this becomes an issue.

Last Resort Fix: Restarting the Server Instance

Stop the instance on the AWS Console. After it stops, start the instance.

On Google Domains, where the harmonylang.dev domain is hosted, go to DNS and route requests to https://www.harmonylang.dev, https://api.harmonylang.dev, and https://harmonylang.dev to the public IP address given in the AWS Console.

SSH into the EC2 Instance, and start docker via sudo service docker start, and start the service pm2 start harmonylang-server/out/index.js --name app.

Making Requests

The production server is deployed via AWS EC2 on https://api.harmonylang.dev.

The server exposes the following API endpoints:

• POST /check
• GET /download/:id

POST /check

POST /check accepts form-data in the following format to run a Harmony program.

Key	Value	Type
file	A zip file containing the Harmony code	File
main	The Harmony program entry filename, relative to the root of the zip. The value is a JSON stringified array, e.g. '["path", "to", "main.hny"]', where each element is a path component	string
source	The source of the API request call, e.g. the IDE	"vscode" | "web-ide"
version	The version of the source sending the request, e.g. the version in package.json	string
options	Any CLI flags to be passed to the Harmony compiler. Only the -c/--const and -m/--module flags are accepted. All other flags will trigger an error response.	string

When the request is successful, the response contains a JSON body with the status for the request, and another related value.

The status value may be one of FAILURE, INTERNAL, COMPLETED, ERROR, TIMEOUT, or OUT OF MEMORY.

The INTERNAL status is returned when an error related to the Harmony compiler occurs.

If the status value is COMPLETED, the model check was successful and no issues were found. If the status value is ERROR, then an error occurred while running the model checker. For these two statuses, the response body contains a message that gives more details about those statuses.

The TIMEOUT and OUT OF MEMORY statuses occur when a Harmony program exceeds the allotted timeout or memory respectively during execution.

If the status value is FAILURE, then the model checker caught a failed invariant in the Harmony program, which could include a failed assertion or deadlock. A response body with this status contains a jsonData value, which is the contents of the charm.json file produced by the (C)Harmony compiler. This jsonData can then be used for further analysis in some other application.

GET /download/:id

GET /download/:id downloads the HTML file generated from running the Harmony uploaded via POST /check, if an model check error occurred. The /download/:id path is a value in the response body of POST /check request (in the staticHtmlLocation field with a value like "/download/<id>" or undefined if no hTML file was generated). Related, the download link is only available for a certain period of time, indicated in the duration field with a number value representing time in milliseconds (this is usually about 5 minutes).

Sample Client Code

The following sample code is in TypeScript. For JavaScript, just remove the type declarations/definitions.

export type CheckResponse = {
    status: "FAILURE";
    jsonData: Record<string, unknown>;
    staticHtmlLocation?: string;
    duration?: number;
} | {
    status: "ERROR" | "INTERNAL" | "COMPLETED" | "TIMEOUT" | "OUT OF MEMORY";
    message: string;
};

export async function makeCheckApiRequest(
    mainFile: string[],
    zipData: Blob,
    source: "vscode" | "web-ide",
    version: string,
    options: string,
): Promise<CheckResponse> {
    const formData = new FormData();
    formData.append("file", zipData, "files.zip");
    formData.append('main', JSON.stringify(mainFile));
    formData.append('version', version);
    formData.append('source', source);
    formData.append('options', options);

    const response = await fetch("https://api.harmonylang.dev/check", {
        method: "POST",
        body: formData
    });
    if (response.ok) {
        return await response.json();
    }
    return Promise.reject(new Error("Failed to make Check API request."))
}