From: Joe Van Dyk <joevandyk@...>
Date: 2005-05-01T01:43:36+09:00
Subject: Re: drb question

On 4/29/05, Ilmari Heikkinen <kig@misfiring.net> wrote:
> 
> On 30.4.2005, at 03:43, Joe Van Dyk wrote:
> 
> > On 4/29/05, Joe Van Dyk <joevandyk@gmail.com> wrote:
> >> class Player
> >>   def initialize
> >>     @player_attributes = { :some_key => "some value", :another_key =>
> >> "another_value" }
> >>     @player_id = 2
> >>   end
> >> end
> >>
> >> Say there's 100 Player objects running.  They're stored in an array.
> >>
> >> DRb clients need access to the data stored in each Player.  The Player
> >> objects get updated every second with new data.
> >>
> >> What's the best way of doing so?  @player_attributes contains about
> >> 20-30 keys and values, if it matters.
> >>
> >> Thanks,
> >> Joe
> >>
> >
> > Oh, and the DRb clients (there's probably only one or two of them at a
> > time) have to use all the values in each Player's attribute list every
> > second or so.
> >
> 
> Depends on the amount of data and the bandwidth of the link. If the
> attributes are roughly 50 bytes per attribute, the player list takes
> 150KB of space, and requires about 1.5Mbps connection to wholly update
> every second. Twice that for two clients.
> 
> If your server can sustain the 3Mbps, you can just send the player
> array over.
> 
> If the link is slow or you don't want to use that much bandwidth, you
> could use some diff algorithm to send only the values that have
> changed.
> 
> Anyhow, you probably want to minimize the amount of DRb calls, as these
> introduce some overhead. So send the changeset with a single call.
> 
> Maybe this was of assistance, maybe not :-I
> 

The player attributes aren't quite 50bytes.. probably a max of 10 or so.

I decided to get rid of DRbUndumped and just Marshal the array of
Players and send it over.

Can someone explain why I couldn't just return the array of Players
through DRb, and why I had to Marshal the array?  I'm confused on this
point.  If I returned the array, then I got an array of DRbUnknown
objects (I think, I tried it a couple days ago).  But If I marshaled
the array and returned that string and then used Marshal.load, it
worked fine.