Synchronous Event Triggers

Space Cloud can process custom events synchronously and return the response from the webhook to the client. Synchronous event triggers are useful only when you want the response back at the client.

How it works

  • Event is queued to Space Cloud with the isSynchronous option set to true in the request body for queueing event.
  • Space Cloud persists the event and then triggers the desired webhooks with the appropriate retry/delivery guarantees.
  • The response in the webhook response body is returned to the client.

Triggering synchronous custom events

You can trigger your custom event either via Mission Control or programmatically via the HTTP API of Space Cloud. An event is made synchronous by specifying the isSynchronous option.


To deliver/queue a synchronous event to Space Cloud, make an HTTP POST request to Space Cloud:



JSON payload:

  "type": "<event-type>",
  "delay": "Number",
  "timestamp": "Number",
  "data": "Object",
  "isSynchronous": true
Key Type Required Default value Description
type String yes Type of event.
timestamp Number no Used to schedule event trigger at the given timestamp (in milliseconds) schedule time for event trigger.
delay Number no 0 Number of seconds to delay the trigger from timestamp.
data Object no null Event data.

For example,

  "type": "sent-email",
  "data": {
    "to": "",
    "from": "",
    "subject": "Some Subject"
  "isSynchronous": true

Invoking synchronous events from Mission Control

Custom event triggers can be invoked via the Mission Control as well.

Head to the Event Triggers section and click the Trigger button for any event trigger in the Actions column to open the following form:

Trigger event screen

Check the Trigger event synchronously option.

Put the event data and hit Trigger.

The event response will be shown in the modal itself like this:

Trigger event screen with response

Delivery mechanism

The webhook is delivered over HTTP POST request to the specified webhook URL with the following headers:

Content-Type: application/json

Event payload

The POST body of the webhook is a JSON object which follows the Cloud Events specs:

  "specversion": "1.0-rc1",
  "id": "<unique-uuid>",
  "type": "<event-type>",
  "source": "<space-cloud-node-id>",
  "time": "<date-string>",
  "data": "Object"
Key Type Description
specversion String Version of the Cloud Events specifications.
id String A unique identifier of an event.
type String Event type.
source String Unique identifier of a Space Cloud instance.
time String Time at which the event occurred(ISO 8601 format).
data Object Event data sent by the client.

For example,

  "specversion": "1.0-rc1",
  "id": "43e32d79-f2bf-41c0-be5f-a75c8c1bcfbf",
  "type": "my-custom-event",
  "source": "1fb07d5d-b670-468e-ba94-ad5f06a5c053",
  "time": "2019-10-19T12:40:50.053Z",
  "data": {
    "key1": "value1"

Webhook response structure

A 2xx response status code from the webhook target is deemed to be a successful invocation of the webhook. Any other response status results in an unsuccessful invocation that causes retries as per the retry configuration.

The response field in the response body of the webhook is returned back to the client. For example:

  "response": {
    "foo": "bar"

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