Events Walkthrough

This walkthrough covers how to build with Dropbox Sign Events and Callbacks (aka "webhooks), which are payloads of event metadata automatically sent to your app when something happens in Dropbox Sign.

This resource centers implementation details, examples, and building with webhooks. For a higher-level overview of Dropbox Sign Events, please refer to the Events Overview section of the documentation.

Event Scoping

When using the Dropbox Sign API, events can occur in two contexts: at the Account level and at the App level. Events that are scoped to an Account are called Account Callbacks while events scoped to an App are called App Callbacks. We recommend referring to their respective pages for more detailed information.

Account Callbacks

Account Callbacks notify your app when an event happens involving your account by sending the event payload to your account callback url. The account callback url can be configured on the Dropbox Sign website or by calling the Dropbox Sign API. You can see examples of both in the Set Account Callback Url section of this walkthrough.

App Callbacks

Setting Up Dropbox Sign Events

Enabling Dropbox Sign Events (webhooks) requires two distinct steps: 1. Setting the callback url at the account or app level, which are both covered in the sections directly below. 2. Responding to the event with to verify it was received.

Set Account Callback Url

• Using Dropbox Sign API to set account callback url

  curl -X POST 'https://api.hellosign.com/v3/account' \
    -u '5b2a72b84c3037711d0578e9f93589a38661f093aa4ea48bd8324c16203364eb:' \
    -F 'callback_url=http://example.com/hs-account-events
    -X POST

• Using Dropbox Sign Web UI to set account callback url

Set App Callback Url

• Configuring app callback url with the Dropbox Sign API

  curl -X POST 'https://api.hellosign.com/v3/api_app/0dd3b823a682527788c4e40cb7b6f7e9' \
    -u '5b2a72b84c3037711d0578e9f93589a38661f093aa4ea48bd8324c16203364eb:' \
    -F 'name=Your Awesome App' \
    -F 'callback_url=http://example.com/hs-app-events' \

• Configuring app callback url with the Dropbox Sign Web UI

Responding to Events

Here's a basic example in Nodejs:

// This sample is stripped down
// Use for reference only
const express = require('express');
const app = express();

app.post('/hs-events', (req, res) => {
    res.set('content-Type', 'text/plain');
    res.status(200).send('Hello API Event Received');
});

Testing your Callback Url

When setting the callback url for your app or account in the Dropbox Sign web UI, you can trigger a test event by clicking the test button next to the field. This is a great way to verify that your webhook handler is responding to events successfully.

Successful response

Failed response

Callback Request Format

Once you've setup a callback url, Dropbox Sign sends event data to that URL in the form of POST requests. This section contains information about how those requests are formatted so you can better understand how to interact with the event data.

Content Type

The Java SDK includes an event parsing class, and you can access this field in the $_POST array on PHP. For other platforms, either a library function, such as cgi.parse_multipart (for python) or ActionDispatch::Http::UploadedFile for Rails, or third party options, such as multer for node, may be useful.

Event Payload

Event Type

{
    "event": {
        "event_time": "1348177752",
        "event_type": "signature_request_sent",
        "event_hash": "3a31324d1919d7cdc849ff407adf38fc01e01107d9400b028ff8c892469ca947",
        "event_metadata": {
            "related_signature_id": "ad4d8a769b555fa5ef38691465d426682bf2c992",
            "reported_for_account_id": "63522885f9261e2b04eea043933ee7313eb674fd",
            "reported_for_app_id": null
        }
    },
    "signature_request": {
        ...
    }
}

if (event.event_type === "signature_request_all_signed") {
  // download completed signature request
}

You can see a complete list of possible events in the Event Names section of the overview page. This list will be updated as new events are added.

HTTP Headers

We provide a couple of headers on callback requests to help you identify them.

Event Hash Verification

Calculating an event_hash

echo -n "${event_time}${event_type}" | openssl dgst -sha256 -hmac "${apikey}"

hash_hmac("sha256", $event_time . $event_type, $apikey);

Mac sha256HMAC = Mac.getInstance("HmacSHA256");
SecretKeySpec secretKey = new SecretKeySpec(apiKey.getBytes(), "HmacSHA256");
sha256HMAC.init(secretKey);
String data = String.valueOf(event_time) + event_type;
String computedHash = bytesToHex(sha256HMAC.doFinal(data.getBytes()));

import hashlib, hmac
hmac.new(apikey, (event_time + event_type), hashlib.sha256).hexdigest()

require 'openssl'
OpenSSL::HMAC.hexdigest(OpenSSL::Digest::Digest.new('sha256'), apikey, (event_time + event_type))

const crypto = require('crypto');
const hash = crypto.createHmac('sha256', apiKey).update(event_time + event_type).digest('hex').toString();

var client = new Client(apiKey);
// The following will throw an EventHashException if the hash is missing or invalid
var event = client.ParseEvent("Callback JSON data here");

Failures and Retries

If your callback url is not reachable or returns a non-successful response, we will retry POSTing the event up to 6 times, with each retry interval being exponentially longer than the previous one. If the sixth retry fails, we will clear your callback url and you must enter a new one to receive future callback events.

Please note that our requests will timeout after 30 seconds, so callbacks will fail if your server takes longer than that to respond. The retry pattern is described below, an alert email will be sent to you after POSTing has failed several times.

Resources

• https://www.hellosign.com/blog/using-hellosign-api-callbacks