Re: [Tarantool-patches] [PATCH 3/6] iproto: Add negotiation phase

[Konstantin Osipov <kostja.osipov@gmail.com>]

* Alexander Turenko <alexander.turenko@tarantool.org> [20/03/27 11:14]:

I think the criteria for making the decision is checking that
clients can cope with extra fields in AUTH response map.

If they do, no need to add a new packet, simply use existing
packet after renaming.

Otherwise introduce a new one.

Please check auth implementation in iproto - AFAIR it flushes the
iproto_msg pipe, so is synchronous. 

We also had a proposal to introduce stream identifiers, necessary
for interactive transactions. Perhaps we need to revive this
proposal to make sure we don't have to change the protocol one
more time to add streams, and introduce all the keys for streams
right away - it's also a session control statement.

> > > * Leonid Vasiliev <lvasiliev@tarantool.org> [20/03/24 16:02]:
> > > > The negotiation phase has been added to IPROTO
> > > > 
> > > > For possibility to have a custom parameters of session the negotiation
> > > > phase has been added. This is necessary to enable the transmission of
> > > > an error in different formats(depending on the choice of the client).
> > > > 
> > > > @TarantoolBot document
> > > > Title: IPROTO: The negatiation phase
> > > > For backward compatibility of the data transmission format,
> > > > the negotiation phase has been added to IPROTO.
> > > > A new key (IPROTO_NEGOTIATION) has been added to IPROTO command codes.
> > > > NEGOTIATION BODY: CODE = 0x0E
> > > > +==========================+
> > > > |                          |
> > > > |  NEGOTIATION PARAMETERS  |
> > > > |                          |
> > > > +==========================+
> > > >             MP_MAP
> > > > Session negotiation parameters are a map with keys like ERROR_FORMAT_VERSION ...
> > > > The response is a map with all stated negotiation parameters.
> > > > So, for work with the new format of errors, it is necessary to perform the negotiation phase,
> > > > otherwise errors will be transmitted in the old format (by default).
> > > 
> > > Why not make it a key in IPROTO_AUTH, and require a separate
> > > round-trip?
> > Hi. Because it's not a part of AAA.
> 
> We discussed it a bit with Leonid and his main concern is naming. AUTH
> is not about session settings.
> 
> We can rename the packet identifier to, say, ALTER_SESSION within our
> code, but keep the code (a number) the same. (Alternative: introduce a
> new ALTER_SESSION packet, which able to authorize and set session
> parameters; don't sure what is better.)
> 
> (If we'll look into the variant with keeping the packet number.) This
> ALTER_SESSION packet should be backward compatible with AUTH by the
> request and response format (at least for responses for requests w/o
> newly introduced fields).
> 
> ALTER_SESSION should support:
> 
> * Request: acquiring a specific value for a session parameter (any of
>   supported session sessings, not only one).
> * Response: explicitly state that all requested settings were applied
>   (to distinguish old/new server responses, the old one will only do
>   authorization).
> * Should support altering of session settings w/o (re)auth.
> 
> Is it looks okay for you, Leonid?

> 
> WBR, Alexander Turenko.

-- 
Konstantin Osipov, Moscow, Russia