7.0.0

Error-handling

Hemera won't catch any thrown error expect you are using async/await. It's up to the developer to handle business specific issues. Ensure that your process is restarted e.g with a process-manager like PM2.

This will crash your application:

hemera.add(
  {
    topic: 'math',
    cmd: 'add'
  },
  function(req, cb) {
    throw new Error()
  }
)

Style

We support error-first-callback style as well as promise and async / await. Use one style but be consistent.

Handle a request error

  • Error-first-callback

    hemera.act(
  {
    topic: 'math',
    cmd: 'add',
    a: 1,
    b: 1
  },
  function(err, resp) {
    if (err) {
      // some code
    }
  }
)

  • Promise

    hemera
  .act({
    topic: 'math',
    cmd: 'add',
    a: 1,
    b: 1
  })
  .catch(err => {
    // some code
  })

  • Async / Await

    try {
  await hemera.act({
    topic: 'math',
    cmd: 'add',
    a: 1,
    b: 1
  })
} catch (err) {
  // some code
}

Respond an error

  • Error-first-callback

    hemera.add(
  {
    topic: 'math',
    cmd: 'add'
  },
  function(req, cb) {
    cb(new Error('Invalid operation'))
  }
)

  • Promise

    hemera.add(
  {
    topic: 'math',
    cmd: 'add'
  },
  function(req) {
    return Promise.reject(new Error('Invalid operation'))
  }
)

  • Async / Await

    hemera.add(
  {
    topic: 'math',
    cmd: 'add'
  },
  async function(req) {
    throw new Error('Invalid operation')
  }
)

Response error

A response error must be derivated from type Error otherwise an error is logged and the client will timeout.

Server error handler

Set a function that will be called whenever an server error happens. Client error are always passed to the callback as first argument.

hemera.setErrorHandler(err => {
  // err.message === 'test'
})
hemera.add(
  {
    topic: 'math',
    cmd: 'add'
  },
  (req, cb) => cb(new Error('test'))
)
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