Easy-serve-0.13

EasyServe: a framework for starting tcp/unix services and connected
clients under one parent process and on remote hosts.

https://github.com/vjoel/easy-serve

gem install easy-serve

Here’s an example that computes (5+6+7)*120 using two service processes
and a remote client (optionally over ssh tunnel):

=============================================
require ‘easy-serve/remote’

tunnel = ARGV.delete("–tunnel")
address_there = ARGV.shift

unless address_there
abort <<-END

 Usage: #$0 address_there [--tunnel]

 The 'address_there' is the remote address on which client code will
 run. It must be a destination accepted by ssh, optionally including
 a user name:

   [[email protected]]hostname

 The 'hostname' may by any valid hostname or ssh alias.

 If --tunnel is specified, use the ssh connection to tunnel the data
 traffic. Otherwise, just use tcp. (Always use ssh to start the
 remote process.)

END
end

EasyServe.start do |ez|
log = ez.log
log.level = Logger::INFO
log.formatter = nil if $VERBOSE

ez.start_services do
host = tunnel ? “localhost” : nil
# no need to expose port if tunnelled

 ez.service "adder", :tcp, bind_host: host do |svr|
   Thread.new do
     loop do
       Thread.new(svr.accept) do |conn|
         begin
           log.info "accepted connection from #{conn.inspect}"
           sum = 0
           while input = conn.gets and not input.empty?
             log.info "read input: #{input.inspect}"
             begin
               sum += Integer(input)
             rescue
               log.error "bad input: #{input}"
               raise
             end
           end
           conn.puts sum
           log.info "wrote sum: #{sum}"
         ensure
           conn.close
         end
       end
     end
   end
 end

 ez.service "multiplier", :tcp, bind_host: host do |svr|
   Thread.new do
     loop do
       Thread.new(svr.accept) do |conn|
         begin
           log.info "accepted connection from #{conn.inspect}"
           prod = 1
           while input = conn.gets and not input.empty?
             log.info "read input: #{input.inspect}"
             begin
               prod *= Integer(input)
             rescue
               log.error "bad input: #{input}"
               raise
             end
           end
           conn.puts prod
           log.info "wrote product: #{prod}"
         ensure
           conn.close
         end
       end
     end
   end
 end

end

ez.remote “adder”, “multiplier”,
host: address_there, tunnel: tunnel, log: true, eval: %{
log.progname = “client on #{host}”
adder, multiplier = conns

 adder.puts 5
 adder.puts 6
 adder.puts 7
 adder.close_write
 log.info "reading from \#{adder.inspect}"
 sum = Integer(adder.read)
 log.info "sum = \#{sum}"
 adder.close

 multiplier.puts sum
 multiplier.puts 10
 multiplier.close_write
 log.info "reading from \#{multiplier.inspect}"
 prod = Integer(multiplier.read)
 log.info "prod = \#{prod}"
 multiplier.close

}

Note use of #{} to interpolate variables that are only available

in the binding where the code is eval-ed. Alternately, use

eval: %Q{…}

but then interpolation from this script is not possible.

end

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