WebUdpCreate Function

Action

Creates an UDP handle, which can be used in subsequent calls to WebUdpXXX functions. If this handle is no longer used, call WebUdpClose to free all associated system resources. The optional IP and port parameters can be used to explicitly bind the UDP socket to a single IP and/or port. This has to be done if a WebUdpRecvFrom function is called before a WebUdpSendTo. If the socket is not bound, the latter function automatically binds it to a system generated port. This port can be queried by the WebUdpGetBindInfo function.

Include file

WebAPI.bdh

Syntax

WebUdpCreate( out hUdp  : number,
              in sIp   : string optional,
              in nPort : number optional ): boolean;

Return value

true if the handle has been created successfully
false otherwise

Parameter	Description
hUdp	UDP handle, that has to be created.
sIp	IP address to bind the UDP socket to (optional). Must be a valid IP address for the local machine. If this parameter is omitted, or a null value is specified no specific IP address is bound. Therefore data can be sent to (and read from) any valid IP of the local host.
nPort	Port to bind the UDP socket to (optional). Specify this parameter to assign a special port to the UDP socket. If this parameter is omitted no special port is assigned and the next WebUdpSendTo function will bind the socket to a system generated port. If this parameter is omitted calls to WebUdpRecvFrom will fail unless the first WebUdpSendTo function is called.

Parameter

Description

hUdp

UDP handle, that has to be created.

sIp

IP address to bind the UDP socket to (optional).

Must be a valid IP address for the local machine. If this parameter is omitted, or a null value is specified no specific IP address is bound. Therefore data can be sent to (and read from) any valid IP of the local host.

nPort

Port to bind the UDP socket to (optional).

Specify this parameter to assign a special port to the UDP socket. If this parameter is omitted no special port is assigned and the next WebUdpSendTo function will bind the socket to a system generated port. If this parameter is omitted calls to WebUdpRecvFrom will fail unless the first WebUdpSendTo function is called.

Example

dcltrans
  transaction TWeb
    var
      nUdp  : number;
      sBuf  : string;
      sIp   : string;
      nPort : number;
  begin
    WebUdpCreate(nUdp, null, 9999);
    WebUdpRecvFrom(nUdp, sBuf, 300, sIp, nPort);
      print("got data from "+sIp+" : "+string(nPort));
    WebUdpClose(nUdp);
      print(sBuf);
  end TWeb;