@foxglove/ws-protocol-examples/dist/esm/ws-protocol-examples/src/examples/service-client.js

Foxglove WebSocket protocol examples

import { MessageWriter as Ros1MessageWriter } from "@foxglove/rosmsg-serialization";
import { MessageWriter as Ros2MessageWriter } from "@foxglove/rosmsg2-serialization";
import { FoxgloveClient } from "@foxglove/ws-protocol";
import { Command } from "commander";
import Debug from "debug";
import WebSocket from "ws";
const log = Debug("foxglove:service-client");
Debug.enable("foxglove:*");
const SUPPORTED_MSG_ENCODINGS = ["json", "ros1", "cdr"];
async function main(url) {
    const address = url.startsWith("ws://") || url.startsWith("wss://") ? url : `ws://${url}`;
    let fallbackMsgEncoding;
    log(`Client connecting to ${address}`);
    const client = new FoxgloveClient({
        ws: new WebSocket(address, [FoxgloveClient.SUPPORTED_SUBPROTOCOL]),
    });
    client.on("error", (error) => {
        log("Error", error);
        throw error;
    });
    client.on("serverInfo", (serverInfo) => {
        const supportedEncodings = serverInfo.supportedEncodings ?? [];
        fallbackMsgEncoding = supportedEncodings.find((encoding) => SUPPORTED_MSG_ENCODINGS.includes(encoding));
    });
    client.on("advertiseServices", (services) => {
        const service = services.find((s) => /std_srvs(\/srv)?\/SetBool/.test(s.type));
        if (!service) {
            return;
        }
        const msgEncoding = service.request?.encoding ?? fallbackMsgEncoding;
        if (msgEncoding == undefined) {
            const supportedEndingsStr = SUPPORTED_MSG_ENCODINGS.join(", ");
            throw new Error(`Unable to call service ${service.name}: No supported message encoding found. Supported encodings: [${supportedEndingsStr}]`);
        }
        let requestData = new Uint8Array();
        if (msgEncoding === "json") {
            requestData = new Uint8Array(Buffer.from(JSON.stringify({ data: true })));
        }
        else if (msgEncoding === "ros1") {
            const writer = new Ros1MessageWriter([{ definitions: [{ name: "data", type: "bool" }] }]);
            requestData = writer.writeMessage({ data: true });
        }
        else {
            const writer = new Ros2MessageWriter([{ definitions: [{ name: "data", type: "bool" }] }]);
            requestData = writer.writeMessage({ data: true });
        }
        client.sendServiceCallRequest({
            serviceId: service.id,
            callId: 123,
            encoding: msgEncoding,
            data: requestData,
        });
    });
    client.on("serviceCallResponse", (response) => {
        if (response.encoding === "json") {
            const responseData = new TextDecoder().decode(response.data);
            console.log(JSON.parse(responseData));
        }
        else if (response.encoding === "ros1") {
            console.log(response);
        }
        else if (response.encoding === "cdr") {
            console.log(response);
        }
        client.close();
    });
    client.on("serviceCallFailure", (event) => {
        console.error(`Failed to call service ${event.serviceId}: ${event.message}`);
        client.close();
    });
}
export default new Command("service-client")
    .description("connect to a server and call the first advertised SetBool service")
    .argument("[url]", "ws(s)://host:port", "ws://localhost:8765")
    .action(main);
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