threez · September 6, 2013 14:11 · Sep 6, 2013
diff --git a/pipe-rpc.rb b/pipe-rpc.rb
@@ -0,0 +1,124 @@
+class Message < Struct.new(:type, :payload)
+  REQUEST  = ?<.freeze
+  RESPONSE = ?>.freeze
+  HEADER = 'NA'.freeze
+  CODER = Marshal
+
+  def self.request(payload)
+    new(REQUEST, payload)
+  end
+
+  def self.response(payload)
+    new(RESPONSE, payload)
+  end
+
+  def self.from_wire(io, expected_type)
+    size, type = io.read(5).unpack(HEADER)
+    unless type == expected_type
+      type_name = (type == REQUEST) ? :request : :response
+      raise ArgumentError, "Response is not of type #{type_name}!"
+    end
+    payload = CODER.load(io.read(size))
+    new(type, payload)
+  end
+
+  def to_wire(io)
+    data = CODER.dump(payload)
+    io.write([data.size, type].pack(HEADER) + data)
+  end
+end
+
+class Protocol
+  def initialize(client, server, message_type = Message)
+    @message_type = message_type
+    @server_read, @client_write = IO.pipe
+    @client_read, @server_write = IO.pipe
+  end
+
+  def send(*arguments)
+    @message_type.request(arguments).to_wire(@client_write)
+    @message_type.from_wire(@client_read, @message_type::RESPONSE).payload
+  end
+
+  def listen(object)
+    message = @message_type.from_wire(@server_read, @message_type::REQUEST)
+    result = object.send(*message.payload)
+    @message_type.response(result).to_wire(@server_write)
+  end
+
+  # close all server streams
+  def client!
+    @server_write.close
+    @server_read.close
+  end
+
+  # close all client streams
+  def server!
+    @client_write.close
+    @client_read.close
+  end
+end
+
+class Client
+  def initialize(server)
+    @protocol = Protocol.new(self, server)
+    server.connected(@protocol)
+  end
+
+  def connect!
+    @protocol.client!
+  end
+
+  def method_missing(*args)
+    @protocol.send(*args)
+  end
+end
+
+class Server
+  def connected(protocol)
+    @protocol = protocol
+  end
+
+  def run
+    @protocol.server!
+    loop do
+      @protocol.listen(self)
+    end
+  end
+end
+
+#
+# Example
+#
+require 'redis'
+
+class CacheServer < Server
+  def initialize
+    @redis = Redis.new path: "redis.sock"
+  end
+
+  def store(name, value)
+    @redis.set(name, value)
+  end
+
+  def fetch(name)
+    @redis.get(name)
+  end
+end
+
+server = CacheServer.new
+client = Client.new(server)
+
+fork { server.run }
+
+client.connect!
+begin
+  print "> "
+
+  case cmd = gets.chomp
+  when /s ([^ ]+) (.*)/ # store 
+    client.store($1, $2)
+  when /f ([^ ]+)/ # fetch
+    puts client.fetch($1)
+  end
+end while !STDIN.eof?