[PATCH] Add CTDB_REQ_TUNNEL for new protocol

[Volker Lendecke]

On Thu, Oct 05, 2017 at 09:47:38PM +1100, Martin Schwenke wrote:
> Hi Volker,
> 
> In case Amitay is completely gone for the evening... he will probably
> explain more eloquently...  :-)
> 
> On Thu, 5 Oct 2017 12:17:40 +0200, Volker Lendecke via samba-technical
> <samba-technical at lists.samba.org> wrote:
> 
> > On Thu, Oct 05, 2017 at 03:59:17PM +1100, Amitay Isaacs via samba-technical wrote:
> > > This is the last set of preparatory patches required for the refactoring
> > > the CTDB daemon code.  With this new components (e.g. cluster manager,
> > > database daemon) can design new protocol and use current CTDB daemon as a
> > > cluster-wide transport.  This allows us to incrementally carve code out of
> > > CTDB daemon.  
> > 
> > This looks really interesting. Question -- what *is* a tunnel?
> 
> Tunnelling provides a new low-level packet type.  A tunnel is then a
> bunch of ctdbd processes registering an common tunnel identifier that
> allows Unix-domain-socket-connected daemons on different nodes to
> communicate with each other. This means the new daemons can have
> new, independent protocols and use ctdbd as a transport by wrapping
> their packets in tunnel packets.
> 
> Later, if we want to, we can re-wire the communication between these
> daemons using some other transport (e.g. proxy).  However, for now we
> just use ctdbd as the transport because it exists and this
> implementation is cheap.  :-)

Our messages are sequenced and reliable. Why not use those?

Volker

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