Find UDP Server

[chkaufmann 17]

I have two applications that communicate in a LAN using UDP. Both applications have TIdUDPClient and a TIdUDPServer. Until now the user must configure the port and the IP address. Now I would like a solution where client computers "find each other" automatically. What is the best way to do that?

 

Regards
Christian

[Der schöne Günther 316]

UDP has a BroadCast(..) method

 

https://stackoverflow.com/a/7424793/2298252

[Fr0sT.Brutal 900]

Send broadcast message with specific payload and address/port of sender

[A.M. Hoornweg 144]

The "clean" way would be to use Bonjour a.k.a.  ZeroConf.

 

https://en.wikipedia.org/wiki/Zero-configuration_networking

 

It is a somewhat "standardized" way of announcing all sorts of services using UDP broadcasts.  Companies like Apple use it for discovering wireless devices such as printers.  A zeroconf  implementation can be found in the Remobjects suite ( https://docs.remotingsdk.com/Clients/Concepts/ROZeroConf/ )  but after some googling I found an open source implementation as well ( https://github.com/deltics/delphi.libs/tree/master/bonjour ).

 

 

 

 

 

[Fr0sT.Brutal 900]

22 hours ago, A.M. Hoornweg said:

The "clean" way would be to use Bonjour a.k.a.  ZeroConf.

Too complex IMHO. Bonjour even requires DLL. But some concepts could be borrowed indeed

[A.M. Hoornweg 144]

The disadvantage of all these broadcast methods is that they don't work across segmented LAN's.   And then there's the can of worms called IPv6.

[Fr0sT.Brutal 900]

What's so terrible in IPv6?

[Rollo62 539]

2 hours ago, A.M. Hoornweg said:

The disadvantage of all these broadcast methods is that they don't work across segmented LAN's.  

If you want to cross segments, the you probably need a central broker,  like MQTT provides.

But I think the original thread request stay inside a local segment, where UDP would be an option.

Edited October 30, 2020 by Rollo62

[Remy Lebeau 1436]

3 hours ago, Fr0sT.Brutal said:

What's so terrible in IPv6?

Subnet broadcasting is supported only in IPv4, not in IPv6, you have to use multicasting instead.

Edited October 30, 2020 by Remy Lebeau

[Dave Nottage 563]

3 hours ago, Remy Lebeau said:

Subnet broadcasting is supported only in IPv4, not in IPv6, you have to use multicasting instead.

..and boy, is that fun 🙄