Delegate · Hemera

If you want to pass data only to the next add you can use delegate$ property. This feature is used to transfer contextual data to tracing systems.

Caveats

Delegate data is transfered
Delegate data is not transfered in childs calls of your add

hemera.act({
  topic: 'math',
  cmd: 'add',
  delegate$: { foo: 'bar' }
})

hemera.add(
  {
    topic: 'math',
    cmd: 'add'
  },
  function(req, cb) {
    this.delegate$.foo
  }
)

Attach it outside of the pattern

hemera.delegate$.a = 'foobar'
hemera.act(
  {
    topic: 'math',
    cmd: 'add',
    a: 1,
    b: 1
  },
  function(err, resp) {}
)