# How to Poll for Large Response Payloads

{% hint style="info" %}
This documentation is specific to handling large response payloads in a Poller integration.
{% endhint %}

Sometimes a polling integration that is fetching data from another system is required to handle response payloads larger than the 5MB limit imposed by ServiceNow. The normal setup for a Poll Processor includes the response payload being returned as a string in the Request script. Here we look at an alternative approach which avoids handling the response payload as a string and so avoids the 5MB string limit.

Alternative approach for response payloads > 5MB:

1. Make the request *(using RESTMessageV2())*.
2. Save the response as an attachment on a record *(using saveResponseBodyAsAttachment())*.
3. Pass the attachment `sys_id` through *(using getResponseAttachmentSysid())*.
4. Fetch it and do something with the newly generated attachment - passing the stream of the attachment on to be processed however required, e.g. text/xml processing.

{% hint style="warning" %}
Don't pass the response body from the request script to the response script. Use **saveResponseBodyAsAttachment()** and **getResponseAttachmentSysid()** instead.
{% endhint %}

## Example Use Case

The following example is taken from our [Incident Attachment Poller Guide](/unifi/4.2/integration-guides/incident-attachment-poller-guide.md).

### Request Script

```javascript
// Process the request e.g. by executing a web service and returning the response
(function (poll_request, poller, connection, params) {

    var request, response;

    request = new sn_ws.RESTMessageV2();
    request.setHttpMethod('GET');
    request.setEndpoint(poll_request.endpoint_url);
    request.setRequestHeader('Content-Type','application/json');
    request.setBasicAuth(connection.getBasicAuthUser(), connection.getBasicAuthPassword());

    // Save the response as a new attachment (on the poll request)
    request.saveResponseBodyAsAttachment(
      poll_request.getTableName(), poll_request.sys_id, params.attachment.file_name
    );

    response = request.execute();

    poll_request.response_code   = response.getStatusCode();
    poll_request.response_status = response.getErrorMessage();
    if (response.haveError()) {
      throw '\nResponse Code: ' + response.getErrorCode() + '\nResponse error: ' + response.getErrorMessage();
    }

    // Return the sys_id of the saved attachment
    answer = response.getResponseAttachmentSysid() + '';

})(poll_request, poller, connection, params);
```

{% hint style="info" %}
**Request script**: This script uses the ServiceNow RESTMessageV2() web service to make a REST call to the endpoint url created in the Setup script. It returns the body of the request as an attachment who's sys\_id it passes to the Response script

**saveResponseBodyAsAttachment()**: This method takes three parameters:

*tableName* - the table that contains the record you want to attach the saved file to.

*recordSysId* - the sys\_id of the record you want to attach the saved file to.

*fileName* - the file name to give to the saved file.

**request.execute()**: The response object returned by request.execute() provides a method called *getResponseAttachmentSysid()*.

**getResponseAttachmentSysid()**: This method returns the `sys_id` of the attachment generated by the REST call.
{% endhint %}

### Response Script

```javascript
// Process the response returned by the request script
// The 'answer' variable from the request script is passed in here as the 'response' parameter 
(function (poll_request, poller, response, params) {

    // Establish the environment
    var poll_helper = new x_snd_eb.PollHelper(poll_request);
    var info = [
        'Incident : ' + params.int_ref,
        '- Attachment file name: ' + params.attachment.file_name,
        '- Attachment id: ' + response
    ];

    // The response should be the sys_id of the created attachment
    params.attachment.data = '<x-attachment-data sys_id="' + response + '" />';

    // Build the payload for Unifi
    var payload = {
        sys_id : params.ext_ref,
        correlation_id : params.int_ref,
        attachment : params.attachment
    };

    // Submit the message into Unifi
    poll_helper.processInbound({
        message_name : 'AddAttachmentInbound',
        payload : JSON.stringify(payload)
    });

    poll_request.response_status = info.join('\n');

})(poll_request, poller, response, params);
```

{% hint style="info" %}
**Response script**: This script sets up some objects to help us; this includes the essential PollHelper() function (which we initialise from the poll\_request) along with the info \[] array.

After that it sets params.attachment.data to the sys\_id of the created attachment, setting up a payload object and submitting it to Unifi by calling the processInbound() method.

After processing the single result, it is logged to the Response status field of the Poll Request.
{% endhint %}

In our example we've taken the inbound attachment, built a payload and passed it to Unifi to process.


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