General questions about coap+tcp usage ?

[sbernard31]

I begin to play with coap-tcp API of java-coap.

I understand this is more or less like CoAP over UDP except I need to :

• use TcpCoapServer.builder(),
• provide TCP capabilities using : .blockSize(...).maxIncomingBlockTransferSize(...).maxMessageSize(...) ,
• provide a CoapTcpTransport.

For the last point (providing a CoapTcpTransport), I only found implementation for client : SocketClientTransport. but nothing for server. Except an out of API SingleConnectionSocketServerTransport class in tests which seems to support only 1 client at a time.

Then I tell myself that maybe there is only server implementation based on netty ? but it seems that NettyCoapTransport implements CoapTransport only.

Did I missed something ? 🤔

[szysas]

Hi, that is correct. There is only client side integration.

[sbernard31]

I feel a little silly because I understood that tcp support was available at client and serve side 😅.

Is server side support in project scope ?
If yes, is it something you plan to add ?

[szysas]

Oh, sorry for misunderstanding. I should clarify that in readme.
I'd say that it is in project scope but there are no plans on adding it.

[sbernard31]

If I want to add coap+tcp support to Leshan, I will need a CoapTcpTransport implementation at server side. 🤔

I will try to work on this in Leshan repository but I guess if I succeed to get a working solution, maybe it will make more sense to add it in java-coap repository ?

Do you already think about how it should looks like ?
Do you think it make sense to go with something based on ServerSocket or we should directly target something based on netty ?

[szysas]

It depends what we want to accomplish. For high load, non blocking, production then definitely netty. For proof of concept or to proof functionality, then maybe easier with ServerSocket.

[sbernard31]

About proof of concept, there is already SingleConnectionSocketServerTransport, not sure we need more ? so unless you discourage me, I will directly try with netty.

[sbernard31]

Still work in progress but my first working version is available at : eclipse-leshan/leshan#1528