WindowActor

The WindowActor is a Coral Actor that enables windowing of events based on count or time. The actor receives individual events but, depending on the settings, waits until a certain time or a certain number of events have been received and then emits a list of the received items.

Creating a WindowActor

The WindowActor has type: "window". The params value is a JSON with a single field:

field	type	required	description
`method`	String	yes	The method of windowing to use, either `count` or `time`.
`number`	Int	yes	The number of milliseconds (in the case of `time`) or number of events (in the case of `count`).
`sliding`	Int	no	The number of events or milliseconds a window should slide. For instance, when sliding == 1 and `method` is `count`, the window moves 1 event every time an event has been received. In the case of `time`, sliding should be specified in milliseconds.

Creation example

{
  "type": "window",
  "params": {
    "method": "count",
    "number": 3,
    "sliding": 1
  }
}

This will create a WindowActor that waits until it receives 3 JSON objects, then emits these 3:

{
   "data": [
      { "name": "object1" },
      { "name": "object2" },
      { "name": "object3" }
   ]
}

Then, object4 comes in, and the WindowActor emits the following:

{
   "data": [
      { "name": "object2" },
      { "name": "object3" },
      { "name": "object4" }
   ]
}

Trigger

The WindowActor is triggered by any incoming JSON event.

Emit

When the right number of objects is collected in the case of count, a list is emitted as in the example above. In the case of time, the actor waits that amount of time and then emits what it has collected, if anything.

State

The WindowActor returns its state as follows:

field	type	description
`method`	String	“count” or “time” as set in the constructor
`number`	Int	The number of objects or the number of milliseconds of the window.
`sliding`	Array	The amount of objects or the amount of milliseconds the window slides every time.

Collect

The WindowActor does not collect state from other actors.

Timer

The WindowActor does not provide timer actions.