UDP_Notify

Description

Designate which UDP/IP events will generate a notification message.

Syntax

n = UDP_Notify(nFile, EventType, hWnd, nMessage)

Returns

Number.

Parameters

Name

Type

Optional

Meaning

nFile

Number

Previously opened file number

EventType

Number

Event type to be trapped. Can be one of the following equates:

•	%NOTIFY_READ

•	%NOTIFY_WRITE

•	%NOTIFY_CLOSE

hWnd

Number

UI Window handle whose callback will receive the message

wMessage

Number

Window message to be passed to Window callback.

This value should be equal or larger than %WM_USER + 500 to avoid conflict with other (common) callback message values.

Remarks

When the callback function receives the wMessage notification, CBWPARAM identifies the operating system's handle of the socket, the low-order Word of CBLPARAM specifies the code of the event (see table below), and the high-order Word of CBLPARAM contains the error code (if any).

LO(WORD, CBLPARAM) can be one of the following:

%FD_READ Data is available to be read from the socket.

%FD_WRITE The socket is ready for data to be written.

%FD_CLOSE The socket has been closed.

Notification messages do not arrive in unabated or continuous streams. That is, once a particular notification message arrives, it will not be sent again until the initial message is acted upon. For example, if a %FD_READ notification is received, it will not be resent until after a UDP_RECV statement is executed.

Restrictions