12:56 p.m.
Hi,
I hope you have all enjoyed the holiday season.
The protocol is an interesting read. There are a few things that stand
out.
- No events. I used events, that is asynchronous messages originating
from the server when certain conditions are met, to notify clients
that data was written to the server. This was mostly driven by the
need to notify an L1 cache of a write to the cache server. It would
be good to allow for this usage in this protocol. Note that this is
another case where the op code is useful to have as part of the
message.
- What happens if the key or the value is not text? I have a way of
representing the data to allow for a wide variety of data types,
even allowing for arrays or maps. This will make the protocol more
complex, but the assumption that the data is a string is rather
limiting. This is already sketched out in the wiki.
- Is the full message size still there as a header field? Is this
necessary? It precludes you from generating messages where you
don't know the full size of the message beforehand. For example,
in the future you might want to write a map of the data in the
cache. I do this, and can chunk the data, thus allowing me to send
an arbitrarily large map. This becomes, to put it mildly, difficult
if you need the size of the request as a header field.
Thanks,
Alex
--- On Mon, 12/21/09, Manik Surtani <manik(a)jboss.org> wrote:
From: Manik Surtani <manik(a)jboss.org>
Subject: Re: [infinispan-dev] Hot Rod - pt3
To: "infinispan -Dev List" <infinispan-dev(a)lists.jboss.org>
Date: Monday, December 21, 2009, 5:36 AM
On 21 Dec 2009, at 11:08, Galder Zamarreno wrote:
> Hi all,
>
> Re: http://community.jboss.org/wiki/HotRodProtocol
>
> First, I've made the corresponding changes based on
the feedback I got
> from pt2. This included reducing the response header
since clients are
> already aware of what they sent, addition of topology
view id to to non
> dumb requests and further specification in responses
when topology
> changes have happened...etc.
>
> I've also added flags to the request header that allow
sending
> Infinispan flags like: skip cache store, zero lock
acquisition
> timeout...etc.
> Note that I've noted this as being N * 1 byte where
each byte represents
> a flag. However, I think this could maybe be sent more
efficiently by
> using XOR, i.e.
>
> 0x00 -> no flag
> 0x01 (0000 0001) -> zero lock acquisition
> 0x02 (0000 0010) -> cache mode local
> 0x03 (0000 0011) -> zero lock acquisition + cache
mode local
> 0x04 (0000 0100) -> skip locking
> ...etc.
>
> With 2 bytes, we could implement 16 Flags, we
currently 11. However, we
> could use vint as well, making sure that the most
significant bit does
> not mean anything flag wise. Iow, with vint, in 1 byte
we'd be able to
> define 7 diff flags. Thoughts?
+1
> I've also added the quit command that disconnects
clients.
Does this have any effect on the servers?
> Finally, as far as I'm concerned, the specification is
complete. I'm
> leaving the quiet commands out of this initial scope
(see
> http://code.google.com/p/memcached/wiki/MemcacheBinaryProtocol).
> Remember that quiet commands could be used so that the
server buffers
> responses and only when you send a non-quiet command,
the server replies
> with all the pending answers.
>
> As you can see at the bottom of the wiki, I've added a
local only put
> request/response example so that readers get an idea
of what a full
> command looks like. I had received some feedback from
readers saying
> that it was difficult to understand how it all fit
together.
The examples look good, however I would not use the
LOCAL_ONLY flag since that flag really only has meaning in a
p2p context. In a client-server context, this flag is
useless, and probably meaningless. I would suggest a
different flag for the example, e.g., ZERO_LOCK_TIMEOUT.
> I'll probably add a couple more examples for
non-so-dumb and clever
> request/responses but I'll held them until we have a
final round of
> feedback and people can indicate whether they want any
other examples
> appearing in the wiki.
>
> Cheers,
> --
> Galder Zamarreño
> Sr. Software Engineer
> Infinispan, JBoss Cache
> _______________________________________________
> infinispan-dev mailing list
> infinispan-dev(a)lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/infinispan-dev
--
Manik Surtani
manik(a)jboss.org
Lead, Infinispan
Lead, JBoss Cache
http://www.infinispan.org
http://www.jbosscache.org
_______________________________________________
infinispan-dev mailing list
infinispan-dev(a)lists.jboss.org
https://lists.jboss.org/mailman/listinfo/infinispan-dev