<note> <p>This is <b>AWS WAF Classic</b> documentation. For more information, see <a href="https://docs.aws.amazon.com/waf/latest/developerguide/classic-waf-chapter.html">AWS WAF Classic</a> in the developer guide.</p> <p> <b>For the latest version of AWS WAF</b>, use the AWS WAFV2 API and see the <a href="https://docs.aws.amazon.com/waf/latest/developerguide/waf-chapter.html">AWS WAF Developer Guide</a>. With the latest version, AWS WAF has a single set of endpoints for regional and global use. </p> </note> <p>Creates a <code>SizeConstraintSet</code>. You then use <a>UpdateSizeConstraintSet</a> to identify the part of a web request that you want AWS WAF to check for length, such as the length of the <code>User-Agent</code> header or the length of the query string. For example, you can create a <code>SizeConstraintSet</code> that matches any requests that have a query string that is longer than 100 bytes. You can then configure AWS WAF to reject those requests.</p> <p>To create and configure a <code>SizeConstraintSet</code>, perform the following steps:</p> <ol> <li> <p>Use <a>GetChangeToken</a> to get the change token that you provide in the <code>ChangeToken</code> parameter of a <code>CreateSizeConstraintSet</code> request.</p> </li> <li> <p>Submit a <code>CreateSizeConstraintSet</code> request.</p> </li> <li> <p>Use <code>GetChangeToken</code> to get the change token that you provide in the <code>ChangeToken</code> parameter of an <code>UpdateSizeConstraintSet</code> request.</p> </li> <li> <p>Submit an <a>UpdateSizeConstraintSet</a> request to specify the part of the request that you want AWS WAF to inspect (for example, the header or the URI) and the value that you want AWS WAF to watch for.</p> </li> </ol> <p>For more information about how to use the AWS WAF API to allow or block HTTP requests, see the <a href="https://docs.aws.amazon.com/waf/latest/developerguide/">AWS WAF Developer Guide</a>.</p>

{
  "success": true,
  "data": {
    "id": "abc123",
    "created_at": "2025-01-01T00:00:00Z"
  }
}

{
  "success": false,
  "error": {
    "code": "VALIDATION_ERROR",
    "message": "Invalid request parameters"
  }
}