I am working on a project involving multicast UDP....

# ktor

[Joris PZ]

I am working on a project involving multicast UDP. As far as I can tell, from the documentation and by looking through the ktor code (in particular UDPSocketBuilder) , there seems to be no way to create a Multicast socket in ktor.

Is that correct? And if so, does anyone know if it's on a roadmap?

[Deactivated User]

https://github.com/ktorio/ktor/blob/e788f34b8a1de91253ed870bc510d3fa08dda5fc/ktor-network/src/io/ktor/network/sockets/Builders.kt#L89

[Deactivated User]

If you miss something, PRs awe welcome

[Deactivated User]

Is this what you would want to support? https://docs.oracle.com/javase/7/docs/api/java/net/MulticastSocket.html

[Joris PZ]

Yep, that's it (or the NIO variant of that, datagram channels can join multicast groups too).

I have been looking through the code to see if I could create a PR, and it doesn't seem too difficult, I'd be happy to give it a go.

[Joris PZ]

OK, so I started looking into this, and am trying to get the most basic 2-way UDP communication (echo server) to work, but no luck so far. The available documentation focuses mostly on TCP, as do the unit tests.

Does anyone have working UDP code I could take a look at?

[Deactivated User]

Do you have the source code?

[Joris PZ]

Of ktor? Yes I do, but unfortunately the UDP code isn't referenced anywhere in it.

[Joris PZ]

Of course it's there, it's just not used in the project itself nor in its unit tests

[Joris PZ]

My next step will be to create a demo project with a straight Kotlin example of what I am trying to do, and a ktor one.

[Joris PZ]

OK I created a gist, with a working example using Threads, and a not-working example using Ktor's sockets. Note that this doesn't have anything to do with multicast yet, I'm just trying to get some basic UDP traffic going.

https://gist.github.com/jorispz/8aa816c96ba15db131335946db8a9a9b

[Joris PZ]

I just realised I should have used NIO in the non-ktor case, I'll update the gist

[Joris PZ]

OK, gist has been upated with a NIO sample, it's hacked together so don't judge the code style 🙂

[Joris PZ]

Just to close this off, I got a basic Ktor implementation working, so for now I'm good