code: public static DatagramPacket getDatagram(String serviceType) {
      StringBuilder sb = new StringBuilder("M-SEARCH * HTTP/1.1\r\n");
      sb.append("HOST: " + SsdpParams.getSsdpMulticastAddress().getHostAddress() + ":" + SsdpParams.getSsdpMulticastPort() + "\r\n");
      sb.append("MAN: \"ssdp:discover\"\r\n");
      sb.append("MX: 3\r\n");
      sb.append("USER-AGENT: Resourcepool SSDP Client\r\n");
      sb.append(serviceType == null ? "ST: ssdp:all\r\n" : "ST: " + serviceType + "\r\n\r\n");
      byte[] content = sb.toString().getBytes(UTF_8);
      return new DatagramPacket(content, content.length, SsdpParams.getSsdpMulticastAddress(), SsdpParams.getSsdpMulticastPort());
    }
docs: Get Datagram from serviceType.
  
  @param serviceType the serviceType
  @return the DatagramPacket matching the search request