Re: [core] #394 (coap-tcp-tls): Ping/pong

Carsten Bormann <cabo@tzi.org> Mon, 13 June 2016 13:07 UTC

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Date: Mon, 13 Jun 2016 14:06:50 +0100
From: Carsten Bormann <cabo@tzi.org>
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Subject: Re: [core] #394 (coap-tcp-tls): Ping/pong
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Right; as the draft says, just about any transport (TCP, TLS, Websocket)
already has a keepalive; it just turns out those may be hard to reach
(or not working very well) in some implementations.

The very simple method of sending and then ignoring empty messages
should provide enough of a keepalive for most applications that need
just that and can't get it from transport.

Ping/pong really is more of an application-layer thing (in particular
with the custody option), so it is definitely not being replaced by
keepalive at any layer (transport or CoAP).

Right now people are doing ping/pong by designating a resource they post
to; this of course will continue to work -- it may just be too much work
in the general case to find the specific resource that has been
designated for this.  But it is useful to keep this in mind before
inventing too much to add to ping/pong -- specialized resources may be
much better for those more specialized purposes.

Grüße, Carsten