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Binds the socket to the port and starts listening.

Component Version macOS Windows Server FileMaker Cloud FileMaker iOS SDK
Socket 3.1 Yes Yes Yes Yes Yes
MBS( "Socket.Listen"; SocketID; Port { ; backlog } )   More


Parameter Description Example value
SocketID The socket ID received by Socket.Connect function. $sock
Port The port number to listen at. 8000
backlog Optional
Available in MBS FileMaker Plugin 9.1 or newer.
The back log for connection.
How many pending connections can be accepted on this socket. Once you call Socket.AcceptNewConnection, an entry is removed here.
Default is 3.


Returns OK or error message.


Binds the socket to the port and starts listening.
For UDP Socket, the socket starts receiving packets.
For TCP Socket, the socket can accept connections which causes a script to be called. You set the script name with Socket.SetNewConnectionHandler. In the script you call Socket.AcceptNewConnection to get a new socket for the new connection.

Be aware that FileMaker Server does not allow the plugin to operate if no script is running. So if you use sockets there, make sure a script is running or paused while you expect an answer coming in.


Listen to a given Port:

Set Variable [$r; Value:MBS("Socket.Listen"; $$sock; 12345)]

Create TCP Socket listening on a port:

Set Variable [$$sock; Value:MBS("Socket.NewTCPSocket")]
If [MBS("IsError")]
    Show Custom Dialog ["Failed to create Socket"; $$sock]
    Exit Script []
End If
Set Variable [$r; Value:MBS("Socket.SetNewConnectionHandler"; $$sock; Get(FileName); "NewConnection")]
Set Variable [$r; Value:MBS("Socket.SetErrorHandler"; $$sock; Get(FileName); "SocketError")]
Set Variable [$r; Value:MBS("Socket.Listen"; $$sock; TCP Receiver::ListenPort)]
If [MBS("IsError")]
    Show Custom Dialog ["Failed to create Socket"; $$sock]
    Exit Script []
End If

See also

Example Databases

Blog Entries

Release notes

Created 18th August 2014, last changed 4th March 2019

Socket.List   -   Socket.LocalIP

Feedback: Report problem or ask question.

MBS Xojo Plugins