From: ahoward <ahoward@...>
Date: 2003-01-31T06:03:32+09:00
Subject: drb experts


drb'ing ruby'ists-

what is the preferred method of server a 'live' ruby object, eg one holding
resources on the local machine, like database connections

a)  distribute the connections directly, perhaps starting a new DrbServer
(once only) for each connection - returning this object to the clients

silly (pseudo-code) :

  class PGconn
    include DRbUndumped
  end

  class PgSqlConnPool
    def initialize (*databases)
      @pgconns = {}
      databases.map {|db| @pgconns[db] = PGconn.new db }
    end

    def pgconn db
      DRbObject.new(nil, (DRb::DRbServer.new(nil, @pgconn[db]).uri)
    end
  end

b)  return a proxy object knowing it's Drb parent, where methods called on the
proxy relay into calls on the main Drb server

silly (pseudo-code) :

  class PGconnProxy
    include DRbUndumped
    def initialize drb, db
      @drb = drb
      @db = db
    end

    def query sql
      @drb.query db, sql
    end
  end

  class PgSqlConnPool
    def initialize (*databases)
      @pgconns = {}
      databases.map {|db| @pgconns[db] = PGconn.new db }
    end

    def pgconn db
      PGconnProxy.new DRbObject.new(nil, self.uri), db
    end

    def query db, sql
      @pgconns[db].query sql
    end
  end


obviously i know very little about drb - but hopefully the overall design will
come through in my bad code.  i'm hopefull that i'll be able to work out the
details myself.  i'm really interested in the best overall design stratagy.

-a




-- 

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 | Ara Howard
 | NOAA Forecast Systems Laboratory
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