Introduction

OneSignal Event Streams allows you to stream data out of OneSignal to your chosen destination. Event streams are a great way to connect OneSignal to other products within your marketing ecosystem, sending events in real-time. This enables your team to trigger corresponding messaging, maintain records, and much more.

Requirements

Events can't be sent unless the following requirements are met:

• A valid URL or IP address pointing to your server HTTP(S) server
• URLs and IP addresses must be publicly routable
• Domains must include a recognized top-level domain (e.g., “.com”, “.net”)

Setup

You can configure a new event stream for your OneSignal application under Settings → Event Streams.

Selecting event stream triggers

Click “Select Events” to select your choice of events to trigger an event stream.

The data that may be sent with these events is all similar enough that you can send events triggered by multiple channels through the same event stream. Another approach would be to define multiple event streams each for a single channel or event for more granular control or to reduce the scale of data sent.

Event stream filters

You can optionally further refine events by specifying the identifiers of one or more messages or templates, enabling you to receive only events related to specific messages within your app. Refer to the instructions below to enable event stream filtering.

Message and template identifiers can be copied by navigating to Messages > Push, Emal, SMS, or Teamlates, -clicking the action button of the desired message or template, and selecting Copy Message ID or Copy Template ID from the action menu.

Alternatively, you can copy the message/template identifier of what you're viewing directly from the URL :

• Template – https://dashboard.onesignal.com/apps/{APP_ID}/templates/{TEMPLATE_ID}
• Push – https://dashboard.onesignal.com/apps/{APP_ID}/notifications/{MESSAGE_ID}
• Email – https://dashboard.onesignal.com/apps/{APP_ID}/email/{MESSAGE_ID}
• SMS – https://dashboard.onesignal.com/apps/{APP_ID}/sms/{MESSAGE_ID}

Configuring the event stream

Select the HTTP method, the URL, and add headers for the event stream this is where authentication will often be. The URl and Headers can contain liquid syntax which will come from both the user properties, but also properties of the event stream.

You may add any headers needed, common examples being an Authorization key, with values like Basic {{YOUR_TOKEN}} or Bearer {{YOUR_TOKEN}} where YOUR_TOKEN is provided by your system or 3rd party. OneSignal does not provide encryption services.

Disallowed headers

The following headers are restricted and can't be set.

• content-length
• referer
• user-agent
• metadata-flavor
• x-google-metadata-request
• host
• x-onesignal*

Body

The body for an event stream will be JSON. The body JSON can be defined either as individual key/value pairs or as an editable code block. To change the input method use the first dropdown under the body heading and select the custom body.

On the right, you can see an example cURL request built from what has been input during event stream setup

Personalization

You can personalize all fields in your event stream using information about the user and the message on whose behalf it was triggered. This gives you the flexibility to use event streams for nearly any use case.
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An event stream event provides access to objects such as event andmessage each with a specific structure. To exemplify, if you need to embed the user's External ID in your event stream URL, you can use a template like: ​<https://example.com/webhook/user/{{event.external_id}}>. This will dynamically inject the user's External ID into the URL.

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Personalizing Messages with Liquid Syntax

For more ways to peronalize your messages usinig Liquid syntax, check out our Using Liquid Syntax Guide.

Event

The event object includes the following properties:

{
  "event.kind": "{{ event.kind }}",
  "event.id": "{{ event.id }}",
  "event.timestamp": "{{ event.timestamp }}",
  "event.datetime": "{{ event.datetime }}",
  "event.app_id": "{{ event.app_id }}",
  "event.subscription_device_type": "{{ event.subscription_device_type }}",
  "event.subscription_id": "{{ event.subscription_id }}",
  "event.onesignal_id": "{{ event.onesignal_id }}",
  "event.external_id": "{{ event.external_id }}"
}

{
  "event.kind": "message.sms.sent",
  "event.id": "ae7eb8b7-5234-475e-886d-966344839600",
  "event.timestamp": "1725412762",
  "event.datetime": "2024-09-04T01:19:22+00:00",
  "event.app_id": "the-onesignal-app-ID",
  "event.subscription_device_type": "SMS",
  "event.subscription_id": "the-subscription-ID",
  "event.onesignal_id": "the-onesignal-ID",
  "event.external_id": "the-users-external-ID"
}

Message

The message object is designed to keep you informed of the messages sent to the end-user. It includes properties like id, template_id, and content which contains the actual text of the message.

{
  "message.id": "f3c9cd09-10d7-4f59-b9bc-66e16607f1d5",  
  "message.name": "the-name-you-set",  
  "message.title": "Claim 50% Off Today",
  "message.title": "{'en':'the message title/headings'}",
  "message.contents": "{'en':'the message content'}",
  "message.template_id": "the-template-uuid-if-set"
}

Check out Message Personalization for more details about how to use liquid templating in general.
Remember that each request represents one message event (if selected for the event stream).

Results & Debugging

You can see how your event stream performs over a period of time on the event stream report page under the 'stats' tab. This will include all-time numbers, the current status of your event stream, and time series data showing what kind of responses the hook has been receiving. Any HTTP response in the 200 range indicates an event was successfully received, while responses in the 400s and 500s indicate errors. A timeout means the server on the other side didn't manage to respond within a reasonable amount of time so OneSignal closed the connection and assumed it failed.

You can see a sampling of recent requests under the 'logs' tab for even more detail. This will show actual requests and the responses from the other side (if applicable). If your event stream has issues, this is a great place to look first. If you need to change/update your event stream, you can edit it on the form page and send test requests to see the full details you need until you can get it right.

Retries / Disabling

When an Event Stream request fails for any recoverable reason (for example status code 429) OneSignal will retry sending the event again after a short delay. This will happen a few times with increasing delays between requests. If enough retries fail in a row, the hook will be marked as 'failed permanently' and will no longer be retried.

If too many separate requests fail in a row, this is probably because of an issue on the receiving end; the receiving end could have errors or have changed/disabled something. OneSignal will continue to send requests to a certain point, but if the requests continue to fail, the event stream might be disabled by OneSignal. If this happens, make sure to spend some time troubleshooting, fixing and then testing the event stream before re-enabling it.

A poorly performing API could lead to event stream disablement. It is important that the API which ingests an event stream is able to handle the volume of events which is produced by message sends. Reviewing the volume of message sends that are produced by your app will reflect the performance required of your API.

We recommend that the API receiving the event stream record an event without any other online processing. This will keep response times low and prevent any latency related issues. Slow response time or status code 429 responses from your API can cause a backlog of events. A consistent backlog of events will lead OneSignal to disable the event stream so you can update your API to handle the required throughput.

Tips for Success

1. You typically will want to have event streams connect to your own servers, not third party services.
   1. While there is nothing wrong with connecting directly to a third party the following can be harder to manage:It will be more challenging to configure/debug
   2. Volume of requests will not be managed in OneSignal.
      1. Event stream events will be sent out as fast as users hit the steps in your journey and this might overwhelm other services, hit rate limits, or run up YOUR bill unexpectedly. This is especially common when trying to use another messaging channel for something like SMS. The flexibility of event streams means OneSignal does not know what you're trying to accomplish with them so you may want to create a simple service of your own that accepts the event stream requests then correctly handles your third party connection limits, rate limits, and queue.
2. Many services have public HTTP APIs which means you can connect to them with an event stream; look for their API docs and examples of how to make an HTTP request to find the right place to get started.