Callback related functions were not working properly

[tkomde]

Hi, I appreciate your wonderful project!!

I tested on the basic BLE device operation, but the Callback related functions were not working properly.
If you could comment on whether it is a code issue or a Node binding issue, that would be helpful.

Enviroments

• Node.js v18.15.0
• Vanilla JS (Not TS)
• MacOS 12.6.3 (I tried it on Windows11 and it still didn't work)

Pattern 1

• simpleble_adapter_set_callback_on_found
• simpleble_adapter_set_callback_on_updated

I added following line in examples/node/scan.mjs (converted TS to JS).

  //Register callback
  bindings.simpleble_adapter_set_callback_on_updated(
    adapter,
    (_adapter, _peripheral, _userdata) => {
	//I want to do something here,,,
    }, null);

But I got a following errror.

# Fatal error in v8::HandleScope::CreateHandle()
# Cannot create a handle without a HandleScope

Pattern 2

• simpleble_adapter_set_callback_on_scan_start
• simpleble_adapter_set_callback_on_scan_stop

I added following line in examples/node/scan.mjs (converted TS to JS).

  //Register callback
  bindings.simpleble_adapter_set_callback_on_scan_start(
    adapter,
    (_adapter, _userdata) => {
    }, null);

But I got a following errror.

ERROR [SimpleBLE] /Users/runner/work/node-simpleble/node-simpleble/SimpleBLE/simpleble/src/backends/macos/AdapterBase.mm:70 scan_start - Exception during callback: Invalid argument

Pattern 3

simpleble_peripheral_notify

Simply I tested examples/node/scan.mjs (converted TS to JS). But as soon as the program received the notification, it occured segmentation fault.

import * as readline from 'node:readline/promises';
import { stdin as input, stdout as output } from 'node:process';
import { bindings } from "simpleble";

function delay(ms) {
  return new Promise((resolve)=> {
    // No need to keep the return value.
    setTimeout(resolve, ms);
  });
}

const SCAN_TIMEOUT = 2000;
const DISCONNECT_TIMEOUT = 5000;

const rl = readline.createInterface({ input, output });

try {
  const adaptersCount = bindings.simpleble_adapter_get_count();
  if (adaptersCount === 0) {
    throw new Error("No Bluetooth adapters found");
  }

  console.log(`Found ${adaptersCount} adapters`);
  const adapter = bindings.simpleble_adapter_get_handle(0);

  console.log(`Starting scan for ${SCAN_TIMEOUT / 1000} seconds`);
  bindings.simpleble_adapter_scan_start(adapter);
  await delay(SCAN_TIMEOUT);
  bindings.simpleble_adapter_scan_stop(adapter);
  console.log(`Finished scan`);

  const resultsCount = bindings.simpleble_adapter_scan_get_results_count(adapter);
  if (resultsCount === 0) {
    throw new Error("No devices found");
  }
  console.log(`Found ${resultsCount} devices`);

  for (let i = 0; i < resultsCount; i++) {
    const d = bindings.simpleble_adapter_scan_get_results_handle(adapter, i);
    const id = bindings.simpleble_peripheral_identifier(d);
    const address = bindings.simpleble_peripheral_address(d);
    const str = id.length > 0 ? `${id} [${address}]` : `[${address}]`;
    console.log(`[${i}] - ${str}`);
  }

  const indexString = await rl.question("Please select a device to connect to: ");
  const index = parseInt(indexString || "", 10);
  if (isNaN(index) || index < 0 || index >= resultsCount) {
    throw new Error("Invalid device selected");
  }

  const device = bindings.simpleble_adapter_scan_get_results_handle(adapter, index);
  const connected = bindings.simpleble_peripheral_connect(device);
  if (!connected) {
    throw new Error("Failed to connect");
  }

  const servicesCount = bindings.simpleble_peripheral_services_count(device);
  console.log(`Found ${servicesCount} services`);
  for (let i = 0; i < servicesCount; i++) {
    const service = bindings.simpleble_peripheral_services_get(device, i);
    console.log(`[${i}] - ${service.uuid}`);
  }

  const serviceString = await rl.question("Please select a service: ");
  const serviceNum = parseInt(serviceString || "", 10);
  if (isNaN(serviceNum) || serviceNum < 0 || serviceNum >= servicesCount) {
    bindings.simpleble_peripheral_disconnect(device);
    throw new Error("Invalid service selected");
  }
  const service = bindings.simpleble_peripheral_services_get(device, serviceNum);

  const charsCount = service.characteristics.length;
  console.log(`Found ${charsCount} characteristics`);
  for (let i = 0; i < charsCount; i++) {
    console.log(`[${i}] ${service.characteristics[i].uuid}`);
  }

  const charString = await rl.question("Please select a characteristic: ");
  const charNum = parseInt(charString || "", 10);
  if (isNaN(charNum) || charNum < 0 || charNum >= charsCount) {
    bindings.simpleble_peripheral_disconnect(device);
    throw new Error("Invalid characteristic selected");
  }
  const char = service.characteristics[charNum];

  const registered = bindings.simpleble_peripheral_notify(device, service.uuid, char.uuid, (_service, _characteristic, data) => {
    const nums = [];
    data.forEach((num) => {
      nums.push(num.toString(16).padStart(2, "0"));
    });
    const arr = nums.join(" ");
    console.log(`Received: ${arr}`);
  }, null);
  if (!registered) {
    console.error("Failed to register notify callback");
    bindings.simpleble_peripheral_disconnect(device);
    process.exit(1);
  }

  console.log(`Disconnecting in ${DISCONNECT_TIMEOUT / 1000} seconds`);

  await delay(DISCONNECT_TIMEOUT);
  console.log("Finished - preparing to disconnect");
  bindings.simpleble_peripheral_unsubscribe(device, service.uuid, char.uuid);
  bindings.simpleble_peripheral_disconnect(device);
  process.exit(0);

} catch (err) {
  console.error(`Error: ${err.message}`);
  process.exit(1);
}

[Symbitic]

@jins-tkomoda yeah, that's a known problem. I figured out the cause is the C++ bindings. It involves how the callback is being called and the pointer parameters.

I've mostly stopped working on Node-SimpleBLE. Instead, I'm trying to work to merge the bindings directly into node-webbluetooth. You can follow along our progress here: thegecko/webbluetooth#44 (comment)
The goal is to have a single cross-platform library that works identically across Node, Deno, and Browsers.

[tkomde]

@Symbitic
Thanks for the reply! I will watch for that project.
If there is anything I can help with, I will help the project.