Check if PDF Auto Signer is running

Audience: Low-code Engineers

Skill Prerequisites: Actions, JavaScript

Checks from the user's browser whether the PDF AutoSigner app is running on the user's computer, then runs your JavaScript with the answer. Use it before Sign PDF to tell users to start the app.

The action is available in forms and listings.

note

The action comes from the PDF AutoSigner integration package (PlantAnApp.Integrations.PdfAutoSigner). If you don't see it, the package isn't installed.

Typical Use Cases

• Show a warning on a signing form when the PDF AutoSigner app isn't running
• Enable a "Sign" button only when the app can be reached
• Help users troubleshoot signing problems

Don't use it to

• Check anything on the server. The check runs in the user's browser, against the user's own computer.
• Run more actions based on the answer. The action ends execution, and the answer arrives later in the browser. Put the follow-up logic in Javascript Code.

Related Actions

Action Name	Description
Sign PDF	Signs a PDF using the PDF AutoSigner app.
Check PDF Signature	Checks whether a PDF has an electronic signature.
Execute Javascript Code And Stop Execution	Runs any JavaScript in the browser and ends execution.

Input Parameter Reference

Parameter	Description	Supports Tokens	Default	Required
Javascript Code	The JavaScript to run when the answer arrives. It can use the result and responseOrError variables described below. Tokens are replaced on the server before the code is sent. In a form, fields are available as form.fields.<FieldName>.value.	Yes	empty string	No

Variables available in the code

Variable	Description
result	true if the app answered, false if it didn't.
responseOrError	When result is true, the app's response, which is the list of signature names available on the computer. When it's false, the error from the browser.

How it works

1. The action ends execution and sends code to the browser. No actions after it run.
2. The browser sends a request to http://localhost:7521/api/sign, where the PDF AutoSigner app listens.
3. When the request succeeds or fails, your code runs with result set to true or false.

Considerations

• The answer is asynchronous. The action finishes before the app answers. Only your code knows the result.
• Errors in your code don't stop anything. The code is wrapped in a try/catch. If it throws, the error is written to the browser console, starting with Execute CheckAutoSignerIsRunning Action Error.
• form is only available in forms. In listings, use other page elements instead of form.fields.
• Running isn't the same as ready. A true result means the app answered. Signing can still fail, for example if the token isn't connected or the PIN is wrong.

Examples

tip

To understand how to use the below examples, please see Running Examples.

1. Tell the user whether the app is running

This action checks the app and shows a message with the outcome.

{
    "Title": "Check if PDF Auto Signer is running",
    "ActionType": "PlantAnApp.PdfAutoSigner.CheckAutoSignerIsRunning",
    "Description": "Check that PDF AutoSigner is running",
    "Parameters": {
        "JsCodeToExecute": "if (result) {\n    alert('PDF AutoSigner is running. You can sign documents.');\n} else {\n    alert('PDF AutoSigner is not running. Please start it and try again.');\n}"
    }
}

2. Show the status on the page

This action writes the status to an HTML element with the ID SignerStatus, for example one placed in the form's layout. When the app is running, it also lists the signatures the app reported.

{
    "Title": "Check if PDF Auto Signer is running",
    "ActionType": "PlantAnApp.PdfAutoSigner.CheckAutoSignerIsRunning",
    "Description": "Show PDF AutoSigner status",
    "Parameters": {
        "JsCodeToExecute": "var el = document.getElementById('SignerStatus');\nif (el) {\n    el.textContent = result\n        ? 'PDF AutoSigner is running. Signatures: ' + [].concat(responseOrError).join(', ')\n        : 'PDF AutoSigner is not running.';\n}"
    }
}

Revised 09/26/2026