Hi Anu,

You can copy the code from Preview script usage in REST Message and paste the same in your business rule.

You can create async business rule for same.

PFB code for your reference

try {
var r = new sn_ws.RESTMessageV2('Demo','Create Incident');
r.setStringParameterNoEscape('Description',current.description);
r.setStringParameterNoEscape('impact',current.impact);
r.setStringParameterNoEscape('short_description',current.short_description)

var response = r.execute();
var responseBody = response.getBody();
var httpStatus = response.getStatusCode();

var responseObj = JSON.parse(responseBody); //Parse response body
var inc = responseObj.number; // get the incident number of target instance

current.correlation_id = inc; // save the number in correlation id field

current.setWorkflow(false);
current.update();
}

catch(ex) {
var message = ex.getMessage();

}

Hope it helps.

Regards,

Monika