@pamoja/loopback

An in-process transport with topic matching and a fault injector, for testing with no broker. One capability of pamoja, one memory-safe Rust core with bindings for TypeScript, Python, and C#.

Install

npm install @pamoja/loopback
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This pulls in @pamoja/native, the compiled engine. npm install pamoja is the whole framework in one package.

Example

The test that runs in CI, spliced here as it ran.

From bindings/node/guides/loopback.ts:

import { LoopbackBroker } from '@pamoja/loopback'

async function main() {
  // One broker and two links off it, all in this process. Nothing binds a port and nothing
  // has to be running for the traffic below to flow, which is what makes this the link to
  // develop a node against before it has a real one.
  const broker = new LoopbackBroker()
  const publisher = broker.link()
  const subscriber = broker.link()
  await publisher.connect()
  await subscriber.connect()

  // A `+` stands for exactly one level, so this takes the mixer's temperature but not the
  // raw reading a level below it.
  await subscriber.subscribe('line/+/temp')
  await publisher.send('line/mixer/temp/raw', Buffer.from('2150'))
  await publisher.send('line/mixer/temp', Buffer.from('21.5'))

  const message = (await subscriber.recv())!
  console.log(`line/+/temp took ${message.payload.toString()} from ${message.topic}`)

  // A `#` covers every level that remains, so a second link takes the whole subtree,
  // including the reading the single-level filter passed over.
  const watcher = broker.link()
  await watcher.connect()
  await watcher.subscribe('line/#')
  await publisher.send('line/mixer/temp/raw', Buffer.from('2150'))

  const deep = (await watcher.recv())!
  console.log(`line/#     took ${deep.payload.toString()} from ${deep.topic}`)

  // A link that has been disconnected reports the failure instead of dropping the reading,
  // which is the case a test wants to reach without unplugging anything.
  await publisher.disconnect()
  try {
    await publisher.send('line/mixer/temp', Buffer.from('21.6'))
    console.log('a disconnected link took a reading, which should never happen')
  } catch (error) {
    console.log(`disconnected refused the reading: ${(error as Error).message}`)
  }

  return { message, deep }
}

main()
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The same capability in every language

Documentation

• @pamoja/loopback reference, every class, function, and type this package exports.
• The Loopback guide, with the same example in Rust, Python, and C#.
• Every capability, and the install page.

License

MIT