如何实现http长连接，有人知道吗？

import { http } from '@kit.NetworkKit'; 
import { BusinessError } from '@kit.BasicServicesKit'; 
 
let httpRequest = http.createHttp(); 
httpRequest.requestInStream("EXAMPLE_URL", (err: BusinessError, data: number) => { 
  if (!err) { 
    console.info("requestInStream OK! ResponseCode is " + JSON.stringify(data)); 
  } else { 
    console.error("requestInStream ERROR : err = " + JSON.stringify(err)); 
  } 
})