Sample Javascript code to to fetch the client id, validate it, and then return it in the response header
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2024. gada 18. sept.
Overview
A webhook is a user-defined HTTPS request triggered when a subscribed event occurs at the source site (Adobe Acrobat Sign, in this case).
Effectively, a webhook is nothing but a REST service that accepts data or a stream of data.
Webhooks are meant for service-to-service communication in a PUSH model.
When a subscribed event is triggered, Acrobat Sign constructs an HTTPS POST with a JSON body and delivers that to the URL specified.
Before configuring webhooks, make sure that your network will accept the IP ranges needed for functionality.
Webhooks offer multiple benefits over the previous callback method, some of which are:
- Admins can enable their webhooks without having to involve Acrobat Sign support to list the callback URL
- Webhooks are better in terms of data "freshness," the efficiency of communication, and security. No polling required
- Webhooks allow for different levels of scope (Account/Group/User/Resource) easily.
- Webhooks are a more modern API solution, allowing for a more straightforward configuration of modern applications
- Multiple webhooks can be configured per scope (Account/Group/User/Resource), where Callbacks were required to be unique
- Webhooks allow for the selection of the data to be returned, where callbacks are an "all or nothing" solution
- Metadata carried with a webhook can be configured (Basic or Detailed)
- Webhooks are far easier to create, edit, or disable as needed since the UI is entirely within the control of the admin.
Piezīme.
This document is primarily focused on the Webhooks UI in the Acrobat Sign web application (Previously Adobe Sign).
Developers that are looking for API details can find more information here:
Prerequisites
You must allow the IP ranges for webhooks through your network security for the service to work.
The legacy callback URL service in REST v5 uses the same IP ranges as the webhook service.
Administrators can log in to the Adobe Admin Console to add users. Once logged in, navigate to the administrator's menu and scroll down to Webhooks.
How it's used
Admins will first need to have a webhook service, ready to accept the inbound push from Acrobat Sign. There are many options in this regard, and as long as the service can accept POST and GET requests, the webhook will be successful.
Once the service is in place, an Acrobat Sign admin can create a new webhook from the Webhook interface in the Account menu of the Acrobat Sign site.
Admins can configure the webhook to trigger for Agreement, Web form (Widget), or Send in Bulk (MegaSign) events. Library Template (Library Document) resource can also be configured through the API.
The scope of the webhook can include the whole account or individual groups through the admin interface. The API allows for more granularity through the selection of USER or RESOURCE scopes.
The type of data that is pushed to the URL is configurable and can include things like the Agreement Info, Participant Info, the Document Info, and so on.
Once the webhook is configured and saved, Acrobat Sign will push a new JSON object to the defined URL every time the subscribed event is triggered. No ongoing manipulation of the webhook is required unless you want to change the event trigger criteria or the JSON payload.
Verification of intent of the webhook URL
Before registering a webhook successfully, Acrobat Sign verifies whether the webhook URL that is provided in the registration request intends to receive notifications or not. For this purpose, when Acrobat Sign receives a new webhook registration request, it first makes a verification request to the webhook URL. This verification request is an HTTPS GET request sent to the webhook URL. This request has a custom HTTP header X-AdobeSign-ClientId. The value in this header is set to the client ID (Application ID) of the API application requesting to create/register the webhook. To successfully register a webhook, the webhook URL must respond to this verification request with a 2XX response code, AND additionally, it MUST send back the same client id value in one of the following two ways:
- Either in a response header X-AdobeSign-ClientId. This is the same header passed in the request and echoed back in the response.
- Or in the JSON response body with the key of xAdobeSignClientId and its value being the same client ID sent in the request.
The webhook will be successfully registered only on a success response(2XX response code) and validation of client id either in header or response body. The purpose of this verification request is to demonstrate that your webhook URL does want to receive notifications at that URL. If you accidentally entered the wrong URL, the URL would fail to respond correctly to the verification of intent request, and Acrobat Sign will not send any notifications to that URL. Additionally, the webhook URL can also validate that it would receive notifications only through the webhooks registered by a specific application. This can be done by validating the client ID of the application passed in the X-AdobeSign-ClientId header. If the webhook URL does not recognize that client id, it MUST NOT respond with the success response code, and Acrobat Sign will take care that the URL is not registered as a webhook.
The verification of the webhook URL call will be made in the following scenarios:
- Registering Webhook: If this verification of the webhook URL call fails, the webhook will not be created.
- Updating Webhook: INACTIVE to ACTIVE: If this verification of the webhook URL call fails, the webhook state will not be changed to ACTIVE.
How to respond to a webhook notification
Acrobat Sign performs an implicit verification of intent in each webhook notification request sent to the webhook URL. Thus, every webhook notification HTTPS request also contains the custom HTTP header called X-AdobeSign-ClientId. The value of this header is the client id (Application ID) of the application that created the webhook. We will consider the webhook notification successfully delivered if, and only if, a success response (2XX response code) is returned and the client id is sent in either the HTTP header (X-AdobeSign-ClientId) or via a JSON response body with key as xAdobeSignClientId and value as the same client id; otherwise we will retry to deliver the notification to the webhook URL until the retries are exhausted.
As mentioned above, the header 'X-AdobeSign-ClientId' which is included in every notification request from Sign, the value of this header(client id) should be echoed back in response in either of two ways:
1. HTTP header X-AdobeSign-ClientId and value as this client id
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// Fetch client id var clientid = request.headers['X-ADOBESIGN-CLIENTID'];
//Validate it if (clientid ==="BGBQIIE7H253K6") //Replace 'BGBQIIE7H253K6' with the client id of the application using which the webhook is created { //Return it in response header response.headers['X-AdobeSign-ClientId'] = clientid; response.status = 200; // default value } |
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Sample PHP code to to fetch the client id, validate it, and then return it in the response header |
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<?php // Fetch client id $clientid = $_SERVER['HTTP_X_ADOBESIGN_CLIENTID']; //Validate it if($clientid == "BGBQIIE7H253K6") //Replace 'BGBQIIE7H253K6' with the client id of the application using which the webhook is created { //Return it in response header header("X-AdobeSign-ClientId:$clientid"); header("HTTP/1.1 200 OK"); // default value } ?> |
2. JSON response body with key as xAdobeSignClientId and value as the same client id
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Sample Javascript code to to fetch the client id, validate it, and return it in the response body |
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// Fetch client id var clientid = request.headers['X-ADOBESIGN-CLIENTID'];
//Validate it if (clientid ==="BGBQIIE7H253K6") //Replace 'BGBQIIE7H253K6' with the client id of the application using which the webhook is created { var responseBody = { "xAdobeSignClientId" : clientid // Return Client Id in the body }; response.headers['Content-Type'] = 'application/json'; response.body = responseBody; response.status = 200; } |
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Sample PHP code to to fetch the client id, validate it, and return it in the response body |
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<?php // Fetch client id $clientid = $_SERVER['HTTP_X_ADOBESIGN_CLIENTID']; //Validate it if($clientid == "BGBQIIE7H253K6") //Replace 'BGBQIIE7H253K6' with the client id of the application using which the webhook is created { //Return it in response body header("Content-Type: application/json"); $body = array('xAdobeSignClientId' => $clientid); echo json_encode($body); header("HTTP/1.1 200 OK"); // default value } ?> |
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Sample JSON body of the response |
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{ "xAdobeSignClientId": "BGBQIIE7H253K6" } |
Prerequisites
You will need:
- A Microsoft account with license to create Azure Functions Applications
- An existing Azure Function Application, you can create one using https://docs.microsoft.com/en-us/azure/azure-functions/functions-create-first-azure-function
- Basic knowledge of Javascript, so that you can understand and write the code in any language of your choice
Steps to create an Azure Functions Trigger that serves as an Acrobat Sign webhook
To create a Javascript HTTP Trigger function:
1. Login via you Microsoft account https://portal.azure.com/
2. Open you Azure Function Application displayed under Function Apps tab.
This will open your list of Azure Function Applications:
3. Choose the application where in you want to create this new function
4. Click on the Create (+) button to create a new Azure function
5. Select Webhook + API as the scenario and Javascript as the language
6. Click Create this function
A new function that has the capability of handling an incoming API request is created.
Add logic to register Acrobat Sign webhook
Before registering a webhook successfully, Acrobat Sign verifies that the webhook URL that is provided in the registration request, really intends to receive notifications or not. For this purpose, when a new webhook registration request is received by Acrobat Sign, it first makes a verification request to the webhook URL. This verification request is an HTTPS GET request sent to the webhook URL with a custom HTTP header X-AdobeSign-ClientId. The value in this header is set to the client ID of the application that is requesting to create/register the webhook. To successfully register a webhook, the webhook URL must respond to this verification request with a 2XX response code AND additionally it must send back the same client id value in one of the following two ways.
There are two options you can follow:
Option 1: Pass Client Id in X-AdobeSign-ClientId as response Header
Pass X-AdobeSign-ClientId in the response header. This is the same header which was passed in the request, and must be echoed back in the response.
Replace the Index.js file with the following:
module.exports = function (context, req) {
var clientId = req.headers['x-adobesign-clientid'];
// Validate that the incoming ClientID is genuine
if (clientId === '123XXX456') {
context.res = {
// status: 200, /* Defaults to 200 */ // any 2XX response is acceptable
body: "Notification Accepted",
headers : {
'x-adobesign-clientid' : req.headers['x-adobesign-clientid']
}
};
}
else {
context.res = {
status: 400,
body: "Opps!! Illegitimate Call identified"
};
}
context.done();
};
Test the behavior by mocking the request:
1. Click on the Test button at extreme right corner
2. Mock the dummy request
Although response headers are not shown above but you can observe it via mocking it by postman/DHC or any other service.
Option 2: Pass Client Id in the response body with key xAdobeSignClientId
In the JSON response body with the key of xAdobeSignClientId and its value being the same client ID that was sent in the request header.
Replace the Index.js file with the following:
module.exports = function (context, req) {
var clientId = req.headers['x-adobesign-clientid'];
// Validate that the incoming ClientID is genuine
if (clientId === '123XXX456') {
context.res = {
// status: 200, /* Defaults to 200 */ // any 2XX response is acceptable
body: {
'xAdobeSignClientId' : clientId
},
headers : {
'Content-Type' : 'application/json'
}
};
}
else {
context.res = {
status: 400,
body: "Opps!! Illegitimate Call identified"
};
}
context.done();
};
Test the behavior by mocking the request
1. Click on the Test button at extreme right corner
2. Mock the dummy request
Also note the same behavior for clientID is expected when the Webhook URL receives POST notifications.
Ready to Use
Once you have verified the behavior, the webhook URL is functional as per Acrobat Sign standards. You can further update the custom logic as per your requirements.
Get the Function URL
- Click on Get function URL
Copy the URL and use it for creating webhooks in Acrobat Sign.
Creating the AWS Lambda function
To create an AWS Lambda function, login to your AWS Management Console and select the AWS Lambda service from the services list.
- Click Create a Lambda function using "Author From Scratch" option
- In the Configure function page enter the function name "lambdaWebhooks" and select Node.js 4.3 as the Runtime
- For the Role choose an existing role or create a new role from template(s)
- If you have chosen Create new role from template(s) enter a role name (e.g. role-lamda) and select Simple Microservices permissions from the Policy templates list
- Click the Create function button
- On the new AWS lamda function page, select "Edit code inline" as "Code entry type", keep the index.handler as Handler.
- Add logic to register the Acrobat Sign Webhook
Before registering a webhook successfully, Acrobat Sign verifies that the webhook URL that is provided in the registration request, really intends to receive notifications or not. For this purpose, when a new webhook registration request is received by Acrobat Sign, it first makes a verification request to the webhook URL. This verification request is an HTTPS GET request sent to the webhook URL with a custom HTTP header X-AdobeSign-ClientId. The value in this header is set to the client ID of the application that is requesting to create/register the webhook. To successfully register a webhook, the webhook URL must respond to this verification request with a 2XX response code AND additionally it must send back the same client id value in one of the following two ways. Also note the same behavior for clientID is expected when the Webhook URL receives POST notifications.
Follow either of the two cases:
Case 1: Pass Client Id in X-AdobeSign-ClientId as response Header
- Pass X-AdobeSign-ClientId in the response header. This is the same header which was passed in the request, and must be echoed back in the response.
Code Snippet
In index.js file, replace the automatically generated code snippet with the following code:
- Pass X-AdobeSign-ClientId in the response header. This is the same header which was passed in the request, and must be echoed back in the response.
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Sample node JS code to to fetch the client id, validate it, and then return it in the response header |
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exports.handler = function index(event, context, callback) { // Fetch client id var clientid = event.headers['X-AdobeSign-ClientId'];
//Validate it if (clientid =="BGBQIIE7H253K6") //Replace 'BGBQIIE7H253K6' with the client id of the application using which the webhook is created { var response = { statusCode: 200, headers: { "X-AdobeSign-ClientId": clientid } }; callback(null,response); } else { callback("Oops!! illegitimate call"); } } |
Case 2: Pass Client Id in the response body with key xAdobeSignClientId
In the JSON response body with the key of xAdobeSignClientId and its value being the same client ID that was sent in the request header.
Code Snippet
Replace the Index.js file with the following :
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Sample node JS code to to fetch the client id, validate it, and then return it in the response header |
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exports.handler = function index(event, context, callback) { // Fetch client id var clientid = event.headers['X-AdobeSign-ClientId'];
//Validate it if (clientid =="BGBQIIE7H253K6") //Replace 'BGBQIIE7H253K6' with the client id of the application using which the webhook is created { var responseBody = { xAdobeSignClientId : clientid };
var response = { statusCode: 200, body: JSON.stringify(responseBody) };
callback(null,response); } else { callback("Opps!! illegitimate call"); } } |
- Save the function. Lambda function is created and we are almost ready to use it in a real-time webhook.
Configuring the AWS API Gateway
To make this Lambda publicly accessible through an HTTP method, we need to configure the AWS API Gateway using our function(created above) as the backend for the API.
In AWS Management Console select the API Gateway from the AWS services and click Create API button
- In the Create new API page select New API and enter webhooks as the API name.
- Click the Create API button
- Select the Actions drop-down list and select the Create Resource option
- Check the Configure as proxy resource option and enter validate as the Resource Name and {proxy+} in the Resource Path
- Leave the Enable API Gateway CORS option unchecked and click the Create Resource button
- Keep the Lambda Function Proxy selected as Integration type and select the region where you have created your Lambda function in the Lambda region drop-down list (probably it's the same region where you are creating the API Gateway).
- Enter validate as the Lambda Function and click the Save button
- In the Add Permission to Lambda Function pop-up window select OK
If all the above steps are executed successfully, you'll see something like this:
Deploying API
The next step is deploying this API so it becomes ready to use.
- In the Actions drop-down select Deploy API
- Select [New Stage] in the Deployment stage and enter prod (or anything you like to identify this stage) in the Stage name
- Click the Deploy button
API is now ready to use and you can find the invoke URL in the blue box as shown below:
Take note of this URL as you'll need to enter it as your real-time webhook URL.
Ready to Use
It's done. Use this above url with "/{nodeJSfunctionName}" appended as webhook url in POST /webhooks API request. Once you have verified the behavior, the Webhook URL is functional as per
Acrobat Sign standards. You can further update/add the custom logic as per your requirement.
How to enable or disable
Access to the Webhooks feature is enabled by default for enterprise tier accounts.
Group-level admins can create/control the Webhooks that operate within their group only.
Access to the Webhooks page can be found in the left rail of the Admin menu.
Concurrency-based rate limiting
Webhook (and callback) creation and notification events are limited in the number of concurrent notifications that are actively being delivered to the customer from the Acrobat Sign system. This limit applies to the account, to include all groups within the account.
This type of rate limiting prevents one poorly designed account from consuming a disproportionate amount of server resources, thereby negatively impacting all other customers in that server environment.
The number of concurrent events per account has been calculated to ensure that accounts with well-behaved webhooks will receive their notifications in the shortest amount of time and should rarely encounter a situation where notifications are delayed due to too many requests. The current thresholds are:
|
Action |
Maximum |
Description |
|
Webhook creation |
10 |
At most, 10 concurrent webhook creation requests are allowed per Account. |
|
Webhook/callback notification |
30 |
At most 30 concurrent webhook and callback notifications are allowed per Account. |
Best Practices
- Subscribe to specific, needed events to limit the number of HTTPS requests to the server - The more specific you can make your webhooks, the less volume you'll need to sift through.
- Be duplicate resistant - If you have more than one app sharing the same webhook URL and the same user mapped to each app, the same event will be sent to your webhook multiple times (once per app). In some cases, your webhook may receive duplicate events. Your webhook application should be tolerant of this and dedupe by event ID.
- Always respond to webhooks quickly - Your app only has five seconds to respond to webhook requests. For the verification request, this is rarely an issue, since your app doesn't need to do any real work to respond. For notification requests, however, your app will usually do something that takes time in response to the request. It is recommended to work on a separate thread or asynchronously using a queue to ensure you can respond within five seconds
- Manage concurrency - When a user makes a number of changes in rapid succession, your app is likely to receive multiple notifications for the same user at roughly the same time. If you're not careful about how you manage concurrency, your app can end up processing the same changes for the same user more than once. In order to take advantage of Acrobat Sign webhooks, a clear understanding of the use of the information needs to be understood. Be sure to ask questions such as:
- What data do you want to return in the payload?
- Who will be accessing this information?
- What decisions or reporting will be generated?
- Recommendations for receiving a signed document - There are several factors to consider when determining how to receive a signed PDF from Acrobat Sign in your document management system.
While it is perfectly acceptable to just select the Agreement Signed Document option while creating a webhook, you might consider using the Acrobat Sign API to retrieve the documents when a triggering event (such as agreement status Complete) is received.
Things to keep in mind...
JSON size limitation
The JSON payload size is limited to 10 MB.
If an event generates a larger payload, a webhook will be triggered but the conditional parameter attributes, if there in the request, will be removed to reduce the size of the payload.
"ConditionalParametersTrimmed " will be returned in the response when this happens to inform the client that the conditionalParameters info has been removed.
“conditionalParametersTrimmed” is an array object containing the information about the keys that have been trimmed.
The truncation will be done in following order :
- includeSignedDocuments
- includeParticipantsInfo
- includeDocumentsInfo
- includeDetailedInfo
Signed Documents will be truncated first, followed by participant info, document info and finally detailed info.
This may happen, for example, on an agreement completion event if it includes signed document (base 64 encoded) as well or for an agreement with multiple form fields
Acrobat Sign webhooks deliver notifications to the sender of the agreement, and any webhook configured within the group from which the agreement was sent. Account scoped webhooks receive all events.
Sender: User A | Signer: User B | Sharee: User C
User A and User B are in different accounts
User A and User C are in different accounts
Use-case |
Notification? |
Comments/Notes |
User A's account has ACCOUNT level webhook (created by User A or Account Admin). |
Yes |
An ACCOUNT level webhook gets notified of all events triggered in that account. |
User A's account has GROUP level webhook (created by User A or Account/Group Admin). Assumption: User A & Group Admin are in the same group. |
Yes |
A GROUP level webhook gets notified of all events triggered in that group. |
User A has USER level webhook. |
Yes |
As the Sender, User A's USER level webhook is triggered |
User A has RESOURCE level webhook (for above-sent agreement). |
Yes |
|
User B's account has ACCOUNT level webhook (created by User B or Account Admin). |
No |
User B's ACCOUNT level webhook is considered a Signer webhook. |
User B's account has GROUP level webhook (created by User B or Account/Group Admin). Assumption: User B & Group Admin are in the same group. |
No |
User B's GROUP level webhook is considered a Signer webhook. |
User B has USER level webhook. |
No |
User B's USER level webhook is considered a Signer webhook. |
User C's account has ACCOUNT level webhook (created by User C or Account Admin). |
No |
User C's ACCOUNT level webhook is considered a non-originator webhook. |
User C's account has GROUP level webhook (created by User C or Account/Group Admin). Assumption: User C & Group Admin are in the same group. |
No |
User C's GROUP level webhook is considered a non-originator webhook. |
User C has USER level webhook. |
No |
User C's USER level webhook is considered a non-originator webhook. |
Sender: User A | Signer: User B | Sharee: User C
User A, User B, and User C are in the same account
Use-case |
Notification? |
Notes |
User A's account has ACCOUNT level webhook (created by User A or Account Admin). |
Yes |
ACCOUNT level webhooks notify for events triggerd by the account. |
User A's account has GROUP level webhook (created by User A or Account/Group Admin). Assumption: User A & Group Admin are in same group. |
Yes |
GROUP level webhooks notify for events triggerd by the users in their group. |
User A has USER level webhook. |
Yes |
As the Sender, User A's User level webhook is triggered |
User A has RESOURCE level webhook (for the above sent agreement). |
Yes |
|
User B's account has ACCOUNT level webhook (created by User B or Account Admin). |
Yes |
Since User A and User B are in the same account, an ACCOUNT level webhook gets notified of all events triggered in that account. |
User B's account has GROUP level webhook (created by User B or Account/Group Admin). Assumption: User A, User B & Group Admin are in same group. |
Yes |
Since User A & User B are in the same group, a GROUP level webhook gets notified of all events triggered in that group. |
User B's account has GROUP level webhook (created by User B or Account/Group Admin). Assumption: User A & User B are in different groups. |
No |
User B's GROUP level webhook is considered a Signer webhook. User A's webhook (RESOURCE/USER/GROUP/ACCOUNT) will be triggered. |
User B has USER level webhook. |
No |
As a recipient, User B's USER level webhook is not triggered. |
User C's account has ACCOUNT level webhook (created by User C or Account Admin). |
Yes |
Since User A and User C are in the same account, an ACCOUNT level webhook gets notified of all events triggered in that account. |
User C's account has GROUP level webhook (created by User C or Account/Group Admin). Assumption: User A, User C & Group Admin are in same group. |
Yes |
Since User A and User C are in the same group, a GROUP level webhook gets notified of all events triggered in that group. |
User C's account has GROUP level webhook (created by User C or Account/Group Admin). Assumption: User A & User C are in different groups. |
No |
User C's GROUP level webhook is considered a non-originator webhook. User A's webhook (RESOURCE/USER/GROUP/ACCOUNT) will be triggered. |
User C has USER level webhook. |
No |
User C's USER level webhook is considered a non-originator webhook. |
Retry when the listening service is down
If the target URL for the webhook is down for any reason, Acrobat Sign will queue the JSON and retry the push in a progressive cycle over 72 hours.
The undelivered events will be persisted in a retry queue and a best effort will be made over the next 72 hours to deliver the notifications in the order they occurred.
The strategy for retrying delivery of notifications is a doubling of time between attempts, starting with a 1-minute interval increasing to every 12 hours, resulting in 15 retries in the space of 72 hours.
If the webhook receiver fails to respond within 72 hours, and there have been no successful notification deliveries in the last seven days, the webhook will be disabled. No notifications will be sent to this URL until the webhook is activated again.
All notifications between the time the webhook is disabled and subsequently enabled again will be lost.
