Difference between revisions of "TWSocket.Listen"
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== Description == | == Description == | ||
| − | '''Listen''' is either used on UDP sockets or on TCP-Server sockets. For UDP-sockets it makes receiving data possible, otherwise no [[TWSocket.OnDataAvailable| | + | '''Listen''' is either used on UDP sockets or on TCP-Server sockets. For UDP-sockets it makes receiving data possible, otherwise no [[TWSocket.OnDataAvailable|OnDataAvailable]] would be triggered, for TCP-Servers it starts to watch for incomming new connections, which trigger [[TWSocket.OnSessionAvailable|OnSessionAvailable]]. Listen does not block the calling thread. It may throw a exception if the ip/port combination the socket should listen on is already in use with the same protocol (TCP/UDP). Some already by TCP used ip/port combination can be used simultaniously by a UDP connection as well. |
== Example == | == Example == | ||
MySocket:=TWSocket.create(nil); | MySocket:=TWSocket.create(nil); | ||
| − | MySocket.addr:='127.0.0.1'; | + | MySocket.addr:='127.0.0.1'; // localhost -> myself |
MySocket.port:='60000'; | MySocket.port:='60000'; | ||
MySOcket.proto:='udp'; | MySOcket.proto:='udp'; | ||
| − | MySocket.Listen; | + | MySocket.Listen; // incomming packets on port 60000 will trigger OnDataAvailable |
== Best practices == | == Best practices == | ||
Latest revision as of 17:40, 2 March 2011
Main page -> ICS component reference -> TWSocket -> Listen
Contents
Definition
method Listen;
Description
Listen is either used on UDP sockets or on TCP-Server sockets. For UDP-sockets it makes receiving data possible, otherwise no OnDataAvailable would be triggered, for TCP-Servers it starts to watch for incomming new connections, which trigger OnSessionAvailable. Listen does not block the calling thread. It may throw a exception if the ip/port combination the socket should listen on is already in use with the same protocol (TCP/UDP). Some already by TCP used ip/port combination can be used simultaniously by a UDP connection as well.
Example
MySocket:=TWSocket.create(nil); MySocket.addr:='127.0.0.1'; // localhost -> myself MySocket.port:='60000'; MySOcket.proto:='udp'; MySocket.Listen; // incomming packets on port 60000 will trigger OnDataAvailable
Best practices
- set up addr and port before calling listen
- put a try/except around the listen call
How to
listen on all network interfaces simultaniously
When you specify 0.0.0.0 as addr, you can listen on the specified port on all available network connections at the same time with the same socket.
