From: Ryan Leavengood <mrcode@...>
Date: 2005-08-10T02:44:41+09:00
Subject: Re: drb server using file/tail to read file, and update client?

Christopher Aldridge said:
>
> Any suggestions or am I doing it the only way it can be done?

If I understand your problem correctly, the issue is that you now have to
constantly poll the server to see if there are more lines, when really
what you want is to have the server tell the clients of the new lines.

So your options are either to code the clients so they also have a DRb
server, which the server connects to when outputting lines from the log
file, or possible to use Rinda and a Tuplespace.

Here is an example of the former:

Server:

require 'drb/drb'

class TailServer
  def initialize
    @clients = []
  end

  def register(uri)
    puts "Client registered at: #{uri}"
    @clients << DRbObject.new(nil, uri)
  end

  def sendline(line)
    puts "Sending line: #{line}"
    @clients.each do |c|
      c.addline(line)
    end
  end
end

ts = TailServer.new
DRb.start_service('druby://localhost:3456', ts)

# Obviously the code below needs to be replaced with code
# that actually tails the log file
i = 0
loop do
  sleep(5)
  ts.sendline("This is line #{i}.")
  i+=1
end
DRb.thread.join

Client:

require 'drb/drb'

class TailClient
  def addline(line)
    puts line
  end
end

# nil in the first parameter opens a random port
DRb.start_service(nil, TailClient.new)
server = DRbObject.new(nil, 'druby://localhost:3456')
server.register(DRb.uri)
DRb.thread.join
__END__

Ryan