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From Avinash Lakshman <avinash.laksh...@gmail.com>
Subject Re: Message classes
Date Sat, 28 Mar 2009 17:39:56 GMT
For eg Thrift will definitely not help in the messages that we use for the
membership protocol. Because there we need to control how big the serialized
messages are - we make sure we serialize a part of the object such that it
fits into an ethernet MTU packet. We do this so that we don't get bitten by
UDP fragmentation. I don't think you could do operations like that in Thrift
based serialization mechanism. We need more control over the serialization
mechanism.

So I don't know if this is something that is insanely important in any
capacity in my opinion. I am sure there are bunch of other reasons I can
come up with - we went through this exercise 2 year back. Of course if you
want to investigate the efficacy I can't stop you from doing so :).

Avinash

On Sat, Mar 28, 2009 at 9:48 AM, Jonathan Ellis <jbellis@gmail.com> wrote:

> One point of clarification -- I don't understand why looking up by
> string is better than using an enum, for instance.  java will autobox
> enums for use in a hashmap lookup.
>
> On Sat, Mar 28, 2009 at 10:34 AM, Avinash Lakshman
> <avinash.lakshman@gmail.com> wrote:
> > Why is it ad-hoc? And it uses a factory pattern and I don't think it hard
> > once you get a hang of it. Consumers of the system are not even going to
> > know about these details. Personally I am never a fan of fixing anything
> > that is not broken - in this case it has been working really well for us.
> > This is now just a matter of what one might prefer. Thrift is something
> that
> > I would not like to see anywhere apart from the entry point. With regards
> to
> > the using the string to lookup the handlers it was done because if you
> don't
> > do that then you will have to resort to RPC style instead of message
> passing
> > or find the handlers based on the kind of messages i.e if-else branching.
> We
> > use non-blocking I/O for all our internal messaging and Thrift using
> > blocking I/O. There is big difference in throughput and also Thrift
> > non-blocking I/O from what I hear is horrendous in performance and
> > stability. My friend you don't have my vote for this :).
> > Avinash
> >
> > On Sat, Mar 28, 2009 at 8:11 AM, Jonathan Ellis <jbellis@gmail.com>
> wrote:
> >
> >> we have a Message class that mostly represents a bunch of bytes (but
> >> sometimes does not, which in some cases causes bugs) and a bunch of
> >> other *Message classes that are not Message subclasses but generate
> >> Message objects (so you have the amusingly redundant Message message =
> >> readResponseMessage.makeReadResponseMessage() in places).
> >>
> >> I think we can replace these ad-hoc and tedious-to-write Message
> >> factories with generated thrift code.  Thrift is good at this and
> >> efficient (currently our message identifiers are inefficient strings
> >> like "ROW-READ-VERB-HANDLER").
> >>
> >> Any objections to investigating replacing the hand-coded messages with
> >> thrift?
> >>
> >
>

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