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Listen for incoming connections.
Syntax
object.Listen( [LocalAddress],
[LocalPort], [Backlog] )
Parameters
- LocalAddress
- An optional string value that specifies the IP address the
control should use when listening for connection requests. If this
argument is not specified, the control will bind to any suitable
IPv4 interface on the local system.
- LocalPort
- An optional integer value that specifies the local port number
that be used to listen for connections. If this parameter is
omitted, the LocalPort property will be used to determine the
default port number. If this value is zero, the listening socket
will be bound to a random port number.
- Backlog
- An optional integer value that specifies the maximum size of the
queue used to manage pending connections to the service. If this
parameter is set to value which exceeds the maximum size allowed by
the operating system, it will be silently adjusted to the nearest
legal value. If this parameter is omitted, the Backlog
property will be used to determine the default value.
Return Value
A value of zero is returned if the operation was successful,
otherwise a non-zero error code is returned which indicates the cause
of the failure. This method will return an error if a socket has
already been created by a previous call to the Connect
method.
Remarks
The Listen method causes the control to listen on a socket
for incoming connections on a particular local address and local
port. If an IPv6 address is specified as the local IP address, the
system must have an IPv6 stack installed and configured, otherwise the
method will fail.
To listen for connections on any suitable IPv4 interface, specify
the special dotted-quad address "0.0.0.0". You can accept
connections from clients using either IPv4 or IPv6 on the same socket by
specifying the special IPv6 address "::0", however this is only
supported on Windows 7 and Windows Server 2008 R2 or later platforms. If
no local address is specified, then the server will only listen for
connections from clients using IPv4. This behavior is by design for
backwards compatibility with systems that do not have an IPv6 TCP/IP
stack installed.
See Also
Backlog Property,
LocalPort Property,
Accept Method,
Connect Method,
Reject Method,
OnAccept Event
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