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Date:      Sat, 30 Jan 1999 21:37:10 +0100
From:      Poul-Henning Kamp <phk@critter.freebsd.dk>
To:        Archie Cobbs <archie@whistle.com>
Cc:        julian@whistle.com, net@FreeBSD.ORG
Subject:   Re: netgraph... 
Message-ID:  <10974.917728630@critter.freebsd.dk>
In-Reply-To: Your message of "Sat, 30 Jan 1999 11:44:54 PST." <199901301944.LAA10242@bubba.whistle.com> 

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In message <199901301944.LAA10242@bubba.whistle.com>, Archie Cobbs writes:
>Poul-Henning Kamp writes:
>> >It's important that control message delivery between nodes be as
>> >fast as possible 
>> 
>> I'm not talking about control messages between nodes, I'm talking
>> ONLY about control messages between ME as root via the ngctl program
>> to some specific node, to get it to do something or other.
>
>OK, that makes sense. I think I wasn't clear before and we're
>actually saying more or less the same thing.. the main points being:
>
>  o ngctl can take an ASCII command and deliver it as a control
>    message to a node, without knowing any specifics of that node
>
>  o 'normal' node to node messages are still sent in binary form
>
>  o no fancy ELF sections or anything

Check! you got a deal mate!

>Now, if you think it would be simpler to also have this control message:
>
>  NGM_DELIVER_ASCII_CTRL_MSG - deliver a control message in ASCII form
>
>then I don't have a problem with that at all. My only point about it
>is that..
>
>  - It's redundant, because you can do the same thing with a
>    NGM_ENCODE_CTRLMSG followed by sending the (binary) message

Why pass it around twice ?

>  - Saving time is not important for ngctl (which mainly interacts
>    with humans).

exactly, but this saves code complexity.

>  - You *still* would need NGM_ENCODE_CTRLMSG and NGM_DECODE_CTRLMSG
>    in order to (for example) print out debugging traces dumps, etc.

I think we should look at the tcpdump model for this.

>> Now I can write a ng module for something, distribute it in binary
>> form only, and the users can still set option "water_pressure=4psi"
>> or whatever they may need to set, without any hocus pocus with ELF
>> sections and all that.
>
>Yes, being able to do this is *very* important I totally agree.

And making it simple to understand for programmers is equally
important, otherwise they tend to figure out all sorts of weird
workarounds for stuff they don't understand...

--
Poul-Henning Kamp             FreeBSD coreteam member
phk@FreeBSD.ORG               "Real hackers run -current on their laptop."
FreeBSD -- It will take a long time before progress goes too far!

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