用ruby写xmlrpc的server和client

#server.rb
#!/usr/bin/env ruby

require "xmlrpc/server"
s = XMLRPC::Server.new(8080)
s.add_handler("test") do |a,b|
  { "sum" => a + b, "difference" => a - b }
end
s.serve


#client.rb
#! /usr/bin/env ruby

require "xmlrpc/client"
server = XMLRPC::Client.new2("http://127.0.0.1:8080")
result = server.call("test", 5, 3)
sum = result["sum"]
difference = result["difference"]
puts "Sum: #{sum}, Difference: #{difference}"



如果把"127.0.0.1"改成"localhost",会报下面的错：
D:\Ruby193\practise>ruby xrpcclient.rb
D:/Ruby193/lib/ruby/1.9.1/net/protocol.rb:141:in `read_nonblock': An existing co
nnection was forcibly closed by the remote host. (Errno::ECONNRESET)
        from D:/Ruby193/lib/ruby/1.9.1/net/protocol.rb:141:in `rbuf_fill'
        from D:/Ruby193/lib/ruby/1.9.1/net/protocol.rb:122:in `readuntil'
        from D:/Ruby193/lib/ruby/1.9.1/net/protocol.rb:132:in `readline'
        from D:/Ruby193/lib/ruby/1.9.1/net/http.rb:2562:in `read_status_line'
        from D:/Ruby193/lib/ruby/1.9.1/net/http.rb:2551:in `read_new'
        from D:/Ruby193/lib/ruby/1.9.1/net/http.rb:1319:in `block in transport_r
equest'
        from D:/Ruby193/lib/ruby/1.9.1/net/http.rb:1316:in `catch'
        from D:/Ruby193/lib/ruby/1.9.1/net/http.rb:1316:in `transport_request'
        from D:/Ruby193/lib/ruby/1.9.1/net/http.rb:1293:in `request'
        from D:/Ruby193/lib/ruby/1.9.1/net/http.rb:1239:in `request_post'
        from D:/Ruby193/lib/ruby/1.9.1/xmlrpc/client.rb:538:in `do_rpc'
        from D:/Ruby193/lib/ruby/1.9.1/xmlrpc/client.rb:420:in `call2'
        from D:/Ruby193/lib/ruby/1.9.1/xmlrpc/client.rb:410:in `call'
        from xrpcclient.rb:5:in `<main>'