diff --git a/examples/agent.lua b/examples/agent.lua
index a2a0a774..fc41802e 100644
--- a/examples/agent.lua
+++ b/examples/agent.lua
@@ -4,7 +4,8 @@ local socket = require "socket"
 local sproto = require "sproto"
 local bit32 = require "bit32"
 
-local rpc
+local host
+local send_request
 
 local CMD = {}
 local REQUEST = {}
@@ -19,11 +20,10 @@ end
 function REQUEST:set()
 	print("set", self.what, self.value)
 	local r = skynet.call("SIMPLEDB", "lua", "set", self.what, self.value)
-	return { ok = true }
 end
 
 function REQUEST:handshake()
-	return { msg = "Welcome to skynet" }
+	return { msg = "Welcome to skynet, I will send heartbeat every 5 sec." }
 end
 
 local function request(name, args, response)
@@ -47,7 +47,7 @@ skynet.register_protocol {
 	name = "client",
 	id = skynet.PTYPE_CLIENT,
 	unpack = function (msg, sz)
-		return rpc:dispatch(msg, sz)
+		return host:dispatch(msg, sz)
 	end,
 	dispatch = function (_, _, type, ...)
 		if type == "REQUEST" then
@@ -67,7 +67,15 @@ skynet.register_protocol {
 }
 
 function CMD.start(gate, fd, proto)
-	rpc = sproto.new(proto):rpc "package"
+	host = sproto.new(proto.c2s):host "package"
+	send_request = host:attach(sproto.new(proto.s2c))
+	skynet.fork(function()
+		while true do
+			send_package(send_request "heartbeat")
+			skynet.sleep(500)
+		end
+	end)
+
 	client_fd = fd
 	skynet.call(gate, "lua", "forward", fd)
 end
diff --git a/examples/client.lua b/examples/client.lua
index a909ee2e..e9efc160 100644
--- a/examples/client.lua
+++ b/examples/client.lua
@@ -6,7 +6,8 @@ local bit32 = require "bit32"
 local proto = require "proto"
 local sproto = require "sproto"
 
-local rpc = sproto.new(proto):rpc "package"
+local host = sproto.new(proto.s2c):host "package"
+local request = host:attach(sproto.new(proto.c2s))
 
 local fd = assert(socket.connect("127.0.0.1", 8888))
 
@@ -52,13 +53,40 @@ local session = 0
 
 local function send_request(name, args)
 	session = session + 1
-	local str = rpc:request(name, args, session)
+	local str = request(name, args, session)
 	send_package(fd, str)
 	print("Request:", session)
 end
 
 local last = ""
 
+local function print_request(name, args)
+	print("REQUEST", name)
+	if args then
+		for k,v in pairs(args) do
+			print(k,v)
+		end
+	end
+end
+
+local function print_response(session, args)
+	print("RESPONSE", session)
+	if args then
+		for k,v in pairs(args) do
+			print(k,v)
+		end
+	end
+end
+
+local function print_package(t, ...)
+	if t == "REQUEST" then
+		print_request(...)
+	else
+		assert(t == "RESPONSE")
+		print_response(...)
+	end
+end
+
 local function dispatch_package()
 	while true do
 		local v
@@ -67,16 +95,12 @@ local function dispatch_package()
 			break
 		end
 
-		local t, session, response = rpc:dispatch(v)
-		assert(t == "RESPONSE" , "This example only support request , so here must be RESPONSE")
-		print("response session", session)
-		for k,v in pairs(response) do
-			print(k,v)
-		end
+		print_package(host:dispatch(v))
 	end
 end
 
 send_request("handshake")
+send_request("set", { what = "hello", value = "world" })
 while true do
 	dispatch_package()
 	local cmd = socket.readstdin()
diff --git a/examples/proto.lua b/examples/proto.lua
index 5cf85b11..31b0c52d 100644
--- a/examples/proto.lua
+++ b/examples/proto.lua
@@ -1,6 +1,8 @@
 local sprotoparser = require "sprotoparser"
 
-local proto = sprotoparser.parse [[
+local proto = {}
+
+proto.c2s = sprotoparser.parse [[
 .package {
 	type 0 : integer
 	session 1 : integer
@@ -17,7 +19,7 @@ get 2 {
 		what 0 : string
 	}
 	response {
-		result 0 : boolean
+		result 0 : string
 	}
 }
 
@@ -26,11 +28,17 @@ set 3 {
 		what 0 : string
 		value 1 : string
 	}
-	response {
-		ok 0 : boolean
-	}
 }
 
 ]]
 
+proto.s2c = sprotoparser.parse [[
+.package {
+	type 0 : integer
+	session 1 : integer
+}
+
+heartbeat 1 {}
+]]
+
 return proto
diff --git a/lualib/sproto.lua b/lualib/sproto.lua
index a6180b0b..e6acd784 100644
--- a/lualib/sproto.lua
+++ b/lualib/sproto.lua
@@ -1,11 +1,12 @@
 local core = require "sproto.core"
+local assert = assert
 
 local sproto = {}
-local rpc = {}
+local host = {}
 
 local weak_mt = { __mode = "kv" }
 local sproto_mt = { __index = sproto }
-local rpc_mt = { __index = rpc }
+local host_mt = { __index = host }
 
 function sproto_mt:__gc()
 	core.deleteproto(self.__cobj)
@@ -27,14 +28,14 @@ function sproto.parse(ptext)
 	return sproto.new(pbin)
 end
 
-function sproto:rpc( packagename )
+function sproto:host( packagename )
 	packagename = packagename or  "package"
 	local obj = {
 		__proto = self,
 		__package = core.querytype(self.__cobj, packagename),
 		__session = {},
 	}
-	return setmetatable(obj, rpc_mt)
+	return setmetatable(obj, host_mt)
 end
 
 local function querytype(self, typename)
@@ -89,35 +90,22 @@ local function queryproto(self, pname)
 end
 
 local header_tmp = {}
-function rpc:request(name, args, session)
-	local proto = queryproto(self.__proto, name)
-	header_tmp.type = proto.tag
-	header_tmp.session = session
-	local header = core.encode(self.__package, header_tmp)
-
-	if session then
-		self.__session[session] = assert(proto.response)
-	end
-
-	if args then
-		local content = core.encode(proto.request, args)
-		return core.pack(header ..  content)
-	else
-		return core.pack(header)
-	end
-end
 
 local function gen_response(self, response, session)
 	return function(args)
 		header_tmp.type = nil
 		header_tmp.session = session
 		local header = core.encode(self.__package, header_tmp)
-		local content = core.encode(response, args)
-		return core.pack(header .. content)
+		if response then
+			local content = core.encode(response, args)
+			return core.pack(header .. content)
+		else
+			return core.pack(header)
+		end
 	end
 end
 
-function rpc:dispatch(...)
+function host:dispatch(...)
 	local bin = core.unpack(...)
 	header_tmp.type = nil
 	header_tmp.session = nil
@@ -126,26 +114,46 @@ function rpc:dispatch(...)
 	if header.type then
 		-- request
 		local proto = queryproto(self.__proto, header.type)
+		local result
 		if proto.request then
-			local result = core.decode(proto.request, content)
-			if header_tmp.session then
-				return "REQUEST", proto.name, result, gen_response(self, proto.response, header_tmp.session)
-			else
-				return "REQUEST", proto.name, result
-			end
+			result = core.decode(proto.request, content)
+		end
+		if header_tmp.session then
+			return "REQUEST", proto.name, result, gen_response(self, proto.response, header_tmp.session)
 		else
-			if header_tmp.session then
-				return "REQUEST", proto.name, nil, gen_response(self, proto.response, header_tmp.session)
-			else
-				return "REQUEST", proto.name
-			end
+			return "REQUEST", proto.name, result
 		end
 	else
 		-- response
 		local session = assert(header_tmp.session, "session not found")
 		local response = assert(self.__session[session], "Unknown session")
 		self.__session[session] = nil
-		return "RESPONSE", session, core.decode(response, content)
+		if response == true then
+			return "RESPONSE", session
+		else
+			local result = core.decode(response, content)
+			return "RESPONSE", session, result
+		end
+	end
+end
+
+function host:attach(sp)
+	return function(name, args, session)
+		local proto = queryproto(sp, name)
+		header_tmp.type = proto.tag
+		header_tmp.session = session
+		local header = core.encode(self.__package, header_tmp)
+
+		if session then
+			self.__session[session] = proto.response or true
+		end
+
+		if args then
+			local content = core.encode(proto.request, args)
+			return core.pack(header ..  content)
+		else
+			return core.pack(header)
+		end
 	end
 end