diff --git a/Makefile b/Makefile
index 63d9085d..1bcb3603 100644
--- a/Makefile
+++ b/Makefile
@@ -43,7 +43,7 @@ jemalloc : $(MALLOC_STATICLIB)
 CSERVICE = snlua logger gate harbor
 LUA_CLIB = skynet socketdriver int64 bson mongo md5 netpack \
   cjson clientsocket memory profile multicast \
-  cluster crypt 
+  cluster crypt sharedata
 
 SKYNET_SRC = skynet_main.c skynet_handle.c skynet_module.c skynet_mq.c \
   skynet_server.c skynet_start.c skynet_timer.c skynet_error.c \
@@ -113,6 +113,9 @@ $(LUA_CLIB_PATH)/cluster.so : lualib-src/lua-cluster.c | $(LUA_CLIB_PATH)
 $(LUA_CLIB_PATH)/crypt.so : lualib-src/lua-crypt.c | $(LUA_CLIB_PATH)
 	$(CC) $(CFLAGS) $(SHARED) $^ -o $@ 
 
+$(LUA_CLIB_PATH)/sharedata.so : lualib-src/lua-sharedata.c | $(LUA_CLIB_PATH)
+	$(CC) $(CFLAGS) $(SHARED) $^ -o $@ 
+
 clean :
 	rm -f $(SKYNET_BUILD_PATH)/skynet $(CSERVICE_PATH)/*.so $(LUA_CLIB_PATH)/*.so
 
diff --git a/examples/share.lua b/examples/share.lua
new file mode 100644
index 00000000..2c81f790
--- /dev/null
+++ b/examples/share.lua
@@ -0,0 +1,63 @@
+local skynet = require "skynet"
+local sharedata = require "sharedata"
+
+local mode = ...
+
+if mode == "host" then
+
+skynet.start(function()
+	skynet.error("new foobar")
+	sharedata.new("foobar", { a=1, b= { "hello",  "world" } })
+
+	skynet.fork(function()
+		skynet.sleep(300)	-- sleep 3s
+		skynet.error("update foobar")
+		sharedata.update("foobar", { a =2 })
+	end)
+end)
+
+else
+
+
+skynet.start(function()
+	skynet.newservice(SERVICE_NAME, "host")
+
+	local obj = sharedata.query "foobar"
+
+	local b = obj.b
+	skynet.error(string.format("a=%d", obj.a))
+
+	for k,v in ipairs(b) do
+		skynet.error(string.format("b[%d]=%s", k,v))
+	end
+
+	for i = 1, 5 do
+		skynet.sleep(100)
+		skynet.error(i)
+		for k,v in pairs(obj) do
+			skynet.error(string.format("%s = %s", k , tostring(v)))
+		end
+	end
+
+	local ok, err = pcall(function()
+		local tmp = { b[1], b[2] }	-- b is invalid , so pcall should failed
+	end)
+
+	if not ok then
+		skynet.error(err)
+	end
+
+	collectgarbage()
+	skynet.error("sleep")
+	skynet.sleep(100)
+	b = nil
+	collectgarbage()
+	skynet.error("sleep")
+	skynet.sleep(100)
+
+	sharedata.delete "foobar"
+
+	skynet.exit()
+end)
+
+end
diff --git a/lualib-src/lua-sharedata.c b/lualib-src/lua-sharedata.c
new file mode 100644
index 00000000..1a0f4f74
--- /dev/null
+++ b/lualib-src/lua-sharedata.c
@@ -0,0 +1,789 @@
+// build: gcc -O2 -Wall --shared -o conf.so luaconf.c 
+
+#include <lua.h>
+#include <lauxlib.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+
+#define KEYTYPE_INTEGER 0
+#define KEYTYPE_STRING 1
+
+#define VALUETYPE_NIL 0
+#define VALUETYPE_NUMBER 1
+#define VALUETYPE_STRING 2
+#define VALUETYPE_BOOLEAN 3
+#define VALUETYPE_TABLE 4
+
+struct table;
+
+union value {
+	lua_Number n;
+	struct table * tbl;
+	int string;
+	int boolean;
+};
+
+struct node {
+	union value v;
+	int key;	// integer key or index of string table
+	int next;	// next slot index
+	uint32_t keyhash;
+	uint8_t keytype;	// key type must be integer or string
+	uint8_t valuetype;	// value type can be number/string/boolean/table
+	uint8_t nocolliding;	// 0 means colliding slot
+};
+
+struct table;
+
+struct state {
+	int dirty;
+	int ref;
+	struct table * root;
+};
+
+struct table {
+	int sizearray;
+	int sizehash;
+	uint8_t *arraytype;
+	union value * array;
+	struct node * hash;
+	lua_State * L;
+};
+
+struct context {
+	lua_State * L;
+	struct table * tbl;
+	int string_index;
+};
+
+struct ctrl {
+	struct table * root;
+	struct table * update;
+};
+
+static int
+countsize(lua_State *L, int sizearray) {
+	int n = 0;
+	lua_pushnil(L);
+	while (lua_next(L, 1) != 0) {
+		int type = lua_type(L, -2);
+		++n;
+		if (type == LUA_TNUMBER) {
+			lua_Number key = lua_tonumber(L, -2);
+			int nkey = (int)key;
+			if ((lua_Number)nkey != key) {
+				luaL_error(L, "Invalid key %f", key);
+			}
+			if (nkey > 0 && nkey <= sizearray) {
+				--n;
+			}
+		} else if (type != LUA_TSTRING && type != LUA_TTABLE) {
+			luaL_error(L, "Invalid key type %s", lua_typename(L, type));
+		}
+		lua_pop(L, 1);
+	}
+
+	return n;
+}
+
+static uint32_t
+calchash(const char * str, size_t l) {
+	uint32_t h = (uint32_t)l;
+	size_t l1;
+	size_t step = (l >> 5) + 1;
+	for (l1 = l; l1 >= step; l1 -= step) {
+		h = h ^ ((h<<5) + (h>>2) + (uint8_t)(str[l1 - 1]));
+	}
+	return h;
+}
+
+static int
+stringindex(struct context *ctx, const char * str, size_t sz) {
+	lua_State *L = ctx->L;
+	lua_pushlstring(L, str, sz);
+	lua_pushvalue(L, -1);
+	lua_rawget(L, 1);
+	int index;
+	// stringmap(1) str index
+	if (lua_isnil(L, -1)) {
+		index = ++ctx->string_index;
+		lua_pop(L, 1);
+		lua_pushinteger(L, index);
+		lua_rawset(L, 1);
+	} else {
+		index = lua_tointeger(L, -1);
+		lua_pop(L, 2);
+	}
+	return index;
+}
+
+static int convtable(lua_State *L);
+
+static void
+setvalue(struct context * ctx, lua_State *L, int index, struct node *n) {
+	int vt = lua_type(L, index);
+	switch(vt) {
+	case LUA_TNIL:
+		n->valuetype = VALUETYPE_NIL;
+		break;
+	case LUA_TNUMBER:
+		n->v.n = lua_tonumber(L, index);
+		n->valuetype = VALUETYPE_NUMBER;
+		break;
+	case LUA_TSTRING: {
+		size_t sz = 0;
+		const char * str = lua_tolstring(L, index, &sz);
+		n->v.string = stringindex(ctx, str, sz);
+		n->valuetype = VALUETYPE_STRING;
+		break;
+	}
+	case LUA_TBOOLEAN:
+		n->v.boolean = lua_toboolean(L, index);
+		n->valuetype = VALUETYPE_BOOLEAN;
+		break;
+	case LUA_TTABLE: {
+		struct table *tbl = ctx->tbl;
+		ctx->tbl = (struct table *)malloc(sizeof(struct table));
+		if (ctx->tbl == NULL) {
+			ctx->tbl = tbl;
+			luaL_error(L, "memory error");
+			// never get here
+		}
+		memset(ctx->tbl, 0, sizeof(struct table));
+		int absidx = lua_absindex(L, index);
+
+		lua_pushcfunction(L, convtable);
+		lua_pushvalue(L, absidx);
+		lua_pushlightuserdata(L, ctx);
+
+		lua_call(L, 2, 0);
+
+		n->v.tbl = ctx->tbl;
+		n->valuetype = VALUETYPE_TABLE;
+
+		ctx->tbl = tbl;
+
+		break;
+	}
+	default:
+		luaL_error(L, "Unsupport value type %s", lua_typename(L, vt));
+		break;
+	}
+}
+
+static void
+setarray(struct context *ctx, lua_State *L, int index, int key) {
+	struct node n;
+	setvalue(ctx, L, index, &n);
+	struct table *tbl = ctx->tbl;
+	--key;	// base 0
+	tbl->arraytype[key] = n.valuetype;
+	tbl->array[key] = n.v;
+}
+
+static int
+ishashkey(struct context * ctx, lua_State *L, int index, int *key, uint32_t *keyhash, int *keytype) {
+	int sizearray = ctx->tbl->sizearray;
+	int kt = lua_type(L, index);
+	if (kt == LUA_TNUMBER) {
+		*key = lua_tointeger(L, index);
+		if (*key > 0 && *key <= sizearray) {
+			return 0;
+		}
+		*keyhash = (uint32_t)*key;
+		*keytype = KEYTYPE_INTEGER;
+	} else {
+		size_t sz = 0;
+		const char * s = lua_tolstring(L, index, &sz);
+		*keyhash = calchash(s, sz);
+		*key = stringindex(ctx, s, sz);
+		*keytype = KEYTYPE_STRING;
+	}
+	return 1;
+}
+
+static void
+fillnocolliding(lua_State *L, struct context *ctx) {
+	struct table * tbl = ctx->tbl;
+	lua_pushnil(L);
+	while (lua_next(L, 1) != 0) {
+		int key;
+		int keytype;
+		uint32_t keyhash;
+		if (!ishashkey(ctx, L, -2, &key, &keyhash, &keytype)) {
+			setarray(ctx, L, -1, key);
+		} else {
+			struct node * n = &tbl->hash[keyhash % tbl->sizehash];
+			if (n->valuetype == VALUETYPE_NIL) {
+				n->key = key;
+				n->keytype = keytype;
+				n->keyhash = keyhash;
+				n->next = -1;
+				n->nocolliding = 1;
+				setvalue(ctx, L, -1, n);	// set n->v , n->valuetype
+			}
+		}
+		lua_pop(L,1);
+	}
+}
+
+static void
+fillcolliding(lua_State *L, struct context *ctx) {
+	struct table * tbl = ctx->tbl;
+	int sizehash = tbl->sizehash;
+	int emptyslot = 0;
+	int i;
+	lua_pushnil(L);
+	while (lua_next(L, 1) != 0) {
+		int key;
+		int keytype;
+		uint32_t keyhash;
+		if (ishashkey(ctx, L, -2, &key, &keyhash, &keytype)) {
+			struct node * mainpos = &tbl->hash[keyhash % tbl->sizehash];
+			if (!(mainpos->keytype == keytype && mainpos->key == key)) {
+				// the key has not insert
+				struct node * n = NULL;
+				for (i=emptyslot;i<sizehash;i++) {
+					if (tbl->hash[i].valuetype == VALUETYPE_NIL) {
+						n = &tbl->hash[i];
+						break;
+					}
+				}
+				assert(n);
+				n->next = mainpos->next;
+				mainpos->next = n - tbl->hash;
+				mainpos->nocolliding = 0;
+				n->key = key;
+				n->keytype = keytype;
+				n->keyhash = keyhash;
+				n->nocolliding = 0;
+				setvalue(ctx, L, -1, n);	// set n->v , n->valuetype
+			}
+		}
+		lua_pop(L,1);
+	}
+}
+
+// table need convert
+// struct context * ctx
+static int
+convtable(lua_State *L) {
+	int i;
+	struct context *ctx = lua_touserdata(L,2);
+	struct table *tbl = ctx->tbl;
+
+	tbl->L = ctx->L;
+
+	int sizearray = lua_rawlen(L, 1);
+	if (sizearray) {
+		tbl->arraytype = (uint8_t *)malloc(sizearray * sizeof(uint8_t));
+		if (tbl->arraytype == NULL) {
+			goto memerror;
+		}
+		for (i=0;i<sizearray;i++) {
+			tbl->arraytype[i] = VALUETYPE_NIL;
+		}
+		tbl->array = (union value *)malloc(sizearray * sizeof(union value));
+		if (tbl->array == NULL) {
+			goto memerror;
+		}
+		tbl->sizearray = sizearray;
+	}
+	int sizehash = countsize(L, sizearray);
+	if (sizehash) {
+		tbl->hash = (struct node *)malloc(sizehash * sizeof(struct node));
+		if (tbl->hash == NULL) {
+			goto memerror;
+		}
+		for (i=0;i<sizehash;i++) {
+			tbl->hash[i].valuetype = VALUETYPE_NIL;
+			tbl->hash[i].nocolliding = 0;
+		}
+		tbl->sizehash = sizehash;
+
+		fillnocolliding(L, ctx);
+		fillcolliding(L, ctx);
+	} else {
+		int i;
+		for (i=1;i<=sizearray;i++) {
+			lua_rawgeti(L, 1, i);
+			setarray(ctx, L, -1, i);
+			lua_pop(L,1);
+		}
+	}
+
+	return 0;
+memerror:
+	return luaL_error(L, "memory error");
+}
+
+static void
+delete_tbl(struct table *tbl) {
+	int i;
+	for (i=0;i<tbl->sizearray;i++) {
+		if (tbl->arraytype[i] == VALUETYPE_TABLE) {
+			delete_tbl(tbl->array[i].tbl);
+		}
+	}
+	for (i=0;i<tbl->sizehash;i++) {
+		if (tbl->hash[i].valuetype == VALUETYPE_TABLE) {
+			delete_tbl(tbl->hash[i].v.tbl);
+		}
+	}
+	free(tbl->arraytype);
+	free(tbl->array);
+	free(tbl->hash);
+	free(tbl);
+}
+
+static int
+pconv(lua_State *L) {
+	struct context *ctx = lua_touserdata(L,1);
+	lua_State * pL = lua_touserdata(L, 2);
+	int ret;
+
+	lua_settop(L, 0);
+
+	// init L (may throw memory error)
+	// create a table for string map
+	lua_newtable(L);
+
+	lua_pushcfunction(pL, convtable);
+	lua_pushvalue(pL,1);
+	lua_pushlightuserdata(pL, ctx);
+
+	ret = lua_pcall(pL, 2, 0, 0);
+	if (ret != LUA_OK) {
+		size_t sz = 0;
+		const char * error = lua_tolstring(pL, -1, &sz);
+		lua_pushlstring(L, error, sz);
+		lua_error(L);
+		// never get here
+	}
+
+	luaL_checkstack(L, ctx->string_index + 3, NULL);
+	lua_settop(L,1);
+
+	return 1;
+}
+
+static void
+convert_stringmap(struct context *ctx, struct table *tbl) {
+	lua_State *L = ctx->L;
+	lua_settop(L, ctx->string_index + 1);
+	lua_pushvalue(L, 1);
+	struct state * s = lua_newuserdata(L, sizeof(*s));
+	s->dirty = 0;
+	s->ref = 0;
+	s->root = tbl;
+	lua_replace(L, 1);
+	lua_replace(L, -2);
+
+	lua_pushnil(L);
+	// ... stringmap nil
+	while (lua_next(L, -2) != 0) {
+		int idx = lua_tointeger(L, -1);
+		lua_pop(L, 1);
+		lua_pushvalue(L, -1);
+		lua_replace(L, idx);
+	}
+
+	lua_pop(L, 1);
+
+	lua_gc(L, LUA_GCCOLLECT, 0);
+}
+
+static int
+lnewconf(lua_State *L) {
+	int ret;
+	struct context ctx;
+	struct table * tbl = NULL;
+	luaL_checktype(L,1,LUA_TTABLE);
+	ctx.L = luaL_newstate();
+	ctx.tbl = NULL;
+	ctx.string_index = 1;	// 1 reserved for dirty flag
+	if (ctx.L == NULL) {
+		lua_pushliteral(L, "memory error");
+		goto error;
+	}
+	tbl = (struct table *)malloc(sizeof(struct table));
+	if (tbl == NULL) {
+		// lua_pushliteral may fail because of memory error, close first.
+		lua_close(ctx.L);
+		ctx.L = NULL;
+		lua_pushliteral(L, "memory error");
+		goto error;
+	}
+	memset(tbl, 0, sizeof(struct table));
+	ctx.tbl = tbl;
+
+	lua_pushcfunction(ctx.L, pconv);
+	lua_pushlightuserdata(ctx.L , &ctx);
+	lua_pushlightuserdata(ctx.L , L);
+
+	ret = lua_pcall(ctx.L, 2, 1, 0);
+
+	if (ret != LUA_OK) {
+		size_t sz = 0;
+		const char * error = lua_tolstring(ctx.L, -1, &sz);
+		lua_pushlstring(L, error, sz);
+		goto error;
+	}
+
+	convert_stringmap(&ctx, tbl);
+
+	lua_pushlightuserdata(L, tbl);	
+
+	return 1;
+error:
+	if (ctx.L) {
+		lua_close(ctx.L);
+	}
+	if (tbl) {
+		delete_tbl(tbl);
+	}
+	lua_error(L);
+	return -1;
+}
+
+static struct table *
+get_table(lua_State *L, int index) {
+	struct table *tbl = lua_touserdata(L,index);
+	if (tbl == NULL) {
+		luaL_error(L, "Need a conf object");
+	}
+	return tbl;
+}
+
+static int
+ldeleteconf(lua_State *L) {
+	struct table *tbl = get_table(L,1);
+	lua_close(tbl->L);
+	delete_tbl(tbl);
+	return 0;
+}
+
+static void
+pushvalue(lua_State *L, lua_State *sL, uint8_t vt, union value *v) {
+	switch(vt) {
+	case VALUETYPE_NUMBER:
+		lua_pushnumber(L, v->n);
+		break;
+	case VALUETYPE_STRING: {
+		size_t sz = 0;
+		const char *str = lua_tolstring(sL, v->string, &sz);
+		lua_pushlstring(L, str, sz);
+		break;
+	}
+	case VALUETYPE_BOOLEAN:
+		lua_pushboolean(L, v->boolean);
+		break;
+	case VALUETYPE_TABLE:
+		lua_pushlightuserdata(L, v->tbl);
+		break;
+	default:
+		lua_pushnil(L);
+		break;
+	}
+}
+
+static struct node *
+lookup_key(struct table *tbl, uint32_t keyhash, int key, int keytype, const char *str, size_t sz) {
+	if (tbl->sizehash == 0)
+		return NULL;
+	struct node *n = &tbl->hash[keyhash % tbl->sizehash];
+	if (keyhash != n->keyhash && n->nocolliding)
+		return NULL;
+	for (;;) {
+		if (keyhash == n->keyhash) {
+			if (n->keytype == KEYTYPE_INTEGER) {
+				if (keytype == KEYTYPE_INTEGER && n->key == key) {
+					return n;
+				}
+			} else {
+				// n->keytype == KEYTYPE_STRING
+				if (keytype == KEYTYPE_STRING) {
+					size_t sz2 = 0;
+					const char * str2 = lua_tolstring(tbl->L, n->key, &sz2);
+					if (sz == sz2 && memcmp(str,str2,sz) == 0) {
+						return n;
+					}
+				}
+			}
+		}
+		if (n->next < 0) {
+			return NULL;
+		}
+		n = &tbl->hash[n->next];		
+	}
+}
+
+static int
+lindexconf(lua_State *L) {
+	struct table *tbl = get_table(L,1);
+	int kt = lua_type(L,2);
+	uint32_t keyhash;
+	int key = 0;
+	int keytype;
+	size_t sz = 0;
+	const char * str = NULL;
+	if (kt == LUA_TNUMBER) {
+		lua_Number k = lua_tonumber(L, 2);
+		key = (int)k;
+		if ((lua_Number)key != k) {
+			return luaL_error(L, "Invalid key %f", k);
+		}
+		if (key > 0 && key <= tbl->sizearray) {
+			--key;
+			pushvalue(L, tbl->L, tbl->arraytype[key], &tbl->array[key]);
+			return 1;
+		} 
+		keytype = KEYTYPE_INTEGER;
+		keyhash = (uint32_t)key;
+	} else {
+		str = luaL_checklstring(L, 2, &sz);
+		keyhash = calchash(str, sz);
+		keytype = KEYTYPE_STRING;
+	}
+
+	struct node *n = lookup_key(tbl, keyhash, key, keytype, str, sz);
+	if (n) {
+		pushvalue(L, tbl->L, n->valuetype, &n->v);
+		return 1;
+	} else {
+		return 0;
+	}
+}
+
+static void
+pushkey(lua_State *L, lua_State *sL, struct node *n) {
+	if (n->keytype == KEYTYPE_INTEGER) {
+		lua_pushinteger(L, n->key);
+	} else {
+		size_t sz = 0;
+		const char * str = lua_tolstring(sL, n->key, &sz);
+		lua_pushlstring(L, str, sz);
+	}
+}
+
+static int
+pushfirsthash(lua_State *L, struct table * tbl) {
+	if (tbl->sizehash) {
+		pushkey(L, tbl->L, &tbl->hash[0]);
+		return 1;
+	} else {
+		return 0;
+	}
+}
+
+static int
+lnextkey(lua_State *L) {
+	struct table *tbl = get_table(L,1);
+	if (lua_isnoneornil(L,2)) {
+		if (tbl->sizearray > 0) {
+			int i;
+			for (i=0;i<tbl->sizearray;i++) {
+				if (tbl->arraytype[i] != VALUETYPE_NIL) {
+					lua_pushinteger(L, i+1);
+					return 1;
+				}
+			}
+		}
+		return pushfirsthash(L, tbl);
+	}
+	int kt = lua_type(L,2);
+	uint32_t keyhash;
+	int key = 0;
+	int keytype;
+	size_t sz=0;
+	const char *str = NULL;
+	int sizearray = tbl->sizearray;
+	if (kt == LUA_TNUMBER) {
+		lua_Number k = lua_tonumber(L,2);
+		key = (int)k;
+		if ((lua_Number)key != k) {
+			return 0;
+		}
+		if (key > 0 && key <= sizearray) {
+			int i;
+			for (i=key;i<sizearray;i++) {
+				if (tbl->arraytype[i] != VALUETYPE_NIL) {
+					lua_pushinteger(L, i+1);
+					return 1;
+				}
+			}
+			return pushfirsthash(L, tbl);
+		}
+		keyhash = (uint32_t)key;
+		keytype = KEYTYPE_INTEGER;
+	} else {
+		str = luaL_checklstring(L, 2, &sz);
+		keyhash = calchash(str, sz);
+		keytype = KEYTYPE_STRING;
+	}
+
+	struct node *n = lookup_key(tbl, keyhash, key, keytype, str, sz);
+	if (n) {
+		++n;
+		int index = n-tbl->hash;
+		if (index == tbl->sizehash) {
+			return 0;
+		}
+		pushkey(L, tbl->L, n);
+		return 1;
+	} else {
+		return 0;
+	}
+}
+
+static int
+llen(lua_State *L) {
+	struct table *tbl = get_table(L,1);
+	lua_pushinteger(L, tbl->sizearray);
+	return 1;
+}
+
+static int
+lhashlen(lua_State *L) {
+	struct table *tbl = get_table(L,1);
+	lua_pushinteger(L, tbl->sizehash);
+	return 1;
+}
+
+static int
+releaseobj(lua_State *L) {
+	struct ctrl *c = lua_touserdata(L, 1);
+	struct table *tbl = c->root;
+	struct state *s = lua_touserdata(tbl->L, 1);
+	__sync_fetch_and_sub(&s->ref, 1);
+	c->root = NULL;
+	c->update = NULL;
+
+	return 0;
+}
+
+static int
+lboxconf(lua_State *L) {
+	struct table * tbl = get_table(L,1);	
+	struct state * s = lua_touserdata(tbl->L, 1);
+	__sync_fetch_and_add(&s->ref, 1);
+
+	struct ctrl * c = lua_newuserdata(L, sizeof(*c));
+	c->root = tbl;
+	c->update = NULL;
+	if (luaL_newmetatable(L, "confctrl")) {
+		lua_pushcfunction(L, releaseobj);
+		lua_setfield(L, -2, "__gc");
+	}
+	lua_setmetatable(L, -2);
+
+	return 1;
+}
+
+static int
+lmarkdirty(lua_State *L) {
+	struct table *tbl = get_table(L,1);
+	struct state * s = lua_touserdata(tbl->L, 1);
+	s->dirty = 1;
+	return 0;
+}
+
+static int
+lisdirty(lua_State *L) {
+	struct table *tbl = get_table(L,1);
+	struct state * s = lua_touserdata(tbl->L, 1);
+	int d = s->dirty;
+	lua_pushboolean(L, d);
+	
+	return 1;
+}
+
+static int
+lgetref(lua_State *L) {
+	struct table *tbl = get_table(L,1);
+	struct state * s = lua_touserdata(tbl->L, 1);
+	lua_pushinteger(L , s->ref);
+
+	return 1;
+}
+
+static int
+lincref(lua_State *L) {
+	struct table *tbl = get_table(L,1);
+	struct state * s = lua_touserdata(tbl->L, 1);
+	int ref = __sync_add_and_fetch(&s->ref, 1);
+	lua_pushinteger(L , ref);
+
+	return 1;
+}
+
+static int
+ldecref(lua_State *L) {
+	struct table *tbl = get_table(L,1);
+	struct state * s = lua_touserdata(tbl->L, 1);
+	int ref = __sync_sub_and_fetch(&s->ref, 1);
+	lua_pushinteger(L , ref);
+
+	return 1;
+}
+
+static int
+lneedupdate(lua_State *L) {
+	struct ctrl * c = lua_touserdata(L, 1);
+	if (c->update) {
+		lua_pushlightuserdata(L, c->update);
+		lua_getuservalue(L, 1);
+		return 2;
+	}
+	return 0;
+}
+
+static int
+lupdate(lua_State *L) {
+	luaL_checktype(L, 1, LUA_TUSERDATA);
+	luaL_checktype(L, 2, LUA_TLIGHTUSERDATA);
+	luaL_checktype(L, 3, LUA_TTABLE);
+	struct ctrl * c= lua_touserdata(L, 1);
+	struct table *n = lua_touserdata(L, 2);
+	if (c->update) {
+		return luaL_error(L, "can't update more than once");
+	}
+	if (c->root == n) {
+		return luaL_error(L, "You should update a new object");
+	}
+	lua_settop(L, 3);
+	lua_setuservalue(L, 1);
+	c->update = n;
+
+	return 0;
+}
+
+int
+luaopen_sharedata_core(lua_State *L) {
+	luaL_Reg l[] = {
+		// used by host
+		{ "new", lnewconf },
+		{ "delete", ldeleteconf },
+		{ "markdirty", lmarkdirty },
+		{ "getref", lgetref },
+		{ "incref", lincref },
+		{ "decref", ldecref },
+
+		// used by client
+		{ "box", lboxconf },
+		{ "index", lindexconf },
+		{ "nextkey", lnextkey },
+		{ "len", llen },
+		{ "hashlen", lhashlen },
+		{ "isdirty", lisdirty },
+		{ "needupdate", lneedupdate },
+		{ "update", lupdate },
+		{ NULL, NULL },
+	};
+	luaL_checkversion(L);
+	luaL_newlib(L, l);
+
+	return 1;
+}
diff --git a/lualib/sharedata.lua b/lualib/sharedata.lua
new file mode 100644
index 00000000..edbf61c5
--- /dev/null
+++ b/lualib/sharedata.lua
@@ -0,0 +1,37 @@
+local skynet = require "skynet"
+local sd = require "sharedata.corelib"
+
+local service
+
+skynet.init(function()
+	service = skynet.uniqueservice "sharedatad"
+end)
+
+local sharedata = {}
+
+local function monitor(name, obj, cobj)
+	local newobj = skynet.call(service, "lua", "monitor", name, cobj)
+	sd.update(obj, newobj)
+end
+
+function sharedata.query(name)
+	local obj = skynet.call(service, "lua", "query", name)
+	local r = sd.box(obj)
+	skynet.send(service, "lua", "confirm" , obj)
+	skynet.fork(monitor,name, r, obj)
+	return r
+end
+
+function sharedata.new(name, v)
+	skynet.call(service, "lua", "new", name, v)
+end
+
+function sharedata.update(name, v)
+	skynet.call(service, "lua", "update", name, v)
+end
+
+function sharedata.delete(name)
+	skynet.call(service, "lua", "delete", name)
+end
+
+return sharedata
diff --git a/lualib/sharedata/corelib.lua b/lualib/sharedata/corelib.lua
new file mode 100644
index 00000000..d9a5488a
--- /dev/null
+++ b/lualib/sharedata/corelib.lua
@@ -0,0 +1,134 @@
+local core = require "sharedata.core"
+local type = type
+local next = next
+local rawget = rawget
+
+local conf = {}
+
+conf.host = {
+	new = core.new,
+	delete = core.delete,
+	getref = core.getref,
+	markdirty = core.markdirty,
+	incref = core.incref,
+	decref = core.decref,
+}
+
+local meta = {}
+
+local isdirty = core.isdirty
+local index = core.index
+local needupdate = core.needupdate
+local len = core.len
+
+local function findroot(self)
+	while self.__parent do
+		self = self.__parent
+	end
+	return self
+end
+
+local function update(root, cobj, gcobj)
+	root.__obj = cobj
+	root.__gcobj = gcobj
+	-- don't use pairs
+	for k,v in next, root do
+		if type(v)=="table" and k~="__parent" then
+			local pointer = index(cobj, k)
+			if type(pointer) == "userdata" then
+				update(v, pointer, gcobj)
+			else
+				root[k] = nil
+			end
+		end
+	end
+end
+
+local function genkey(self)
+	local key = tostring(self.__key)
+	while self.__parent do
+		self = self.__parent
+		key = self.__key .. "." .. key
+	end
+	return key
+end
+
+function meta:__index(key)
+	local obj = self.__obj
+	if isdirty(obj) then
+		local newobj, newtbl = needupdate(self.__gcobj)
+		if newobj then
+			local newgcobj = newtbl.__gcobj
+			-- todo: update
+			local root = findroot(self)
+			update(root, newobj, newgcobj)
+			if obj == self.__obj then
+				error ("The key [" .. genkey(self) .. "] doesn't exist after update")
+			end
+		end
+	end
+	local v = index(self.__obj, key)
+	if type(v) == "userdata" then
+		local r = setmetatable({
+			__obj = v,
+			__gcobj = self.__gcobj,
+			__parent = self,
+			__key = key,
+		}, meta)
+		self[key] = r
+		return r
+	else
+		return v
+	end
+end
+
+function meta:__len()
+	return len(self.__obj)
+end
+
+local function conf_ipairs(self, index)
+	local obj = self.__obj
+	index = index + 1
+	local value =  rawget(self, index)
+	if value then
+		return index, value
+	end
+	local sz = len(obj)
+	if sz < index then
+		return
+	end
+	return index, self[index]
+end
+
+function meta:__ipairs()
+	return conf_ipairs, self, 0
+end
+
+function meta:__pairs()
+	return conf.next, self, nil
+end
+
+function conf.next(obj, key)
+	local nextkey = core.nextkey(obj.__obj, key)
+	if nextkey then
+		return nextkey, obj[nextkey]
+	end
+end
+
+function conf.box(obj)
+	local gcobj = core.box(obj)
+	return setmetatable({
+		__parent = false,
+		__obj = obj,
+		__gcobj = gcobj,
+		__key = "",
+	} , meta)
+end
+
+function conf.update(self, pointer)
+	local cobj = self.__obj
+	assert(isdirty(cobj), "Obly dirty object can be update")
+	core.update(self.__gcobj, pointer, { __gcobj = core.box(pointer) })
+end
+
+return conf
\ No newline at end of file
diff --git a/service/sharedatad.lua b/service/sharedatad.lua
new file mode 100644
index 00000000..7ce24b89
--- /dev/null
+++ b/service/sharedatad.lua
@@ -0,0 +1,121 @@
+local skynet = require "skynet"
+local sharedata = require "sharedata.corelib"
+local table = table
+
+local NORET = {}
+local pool = {}
+local objmap = {}
+
+local function newobj(name, tbl)
+	assert(pool[name] == nil)
+	local cobj = sharedata.host.new(tbl)
+	sharedata.host.incref(cobj)
+	local v = { value = tbl , obj = cobj, watch = {} }
+	objmap[cobj] = v
+	pool[name] = v
+end
+
+local function collectobj()
+	while true do
+		skynet.sleep(600 * 100)	-- sleep 10 min
+		collectgarbage()
+		for obj, v in pairs(objmap) do
+			if v == true then
+				if sharedata.host.getref(obj) <= 0  then
+					objmap[obj] = nil
+					print("collect", obj)
+					sharedata.host.delete(obj)
+				end
+			end
+		end
+	end
+end
+
+local CMD = {}
+
+function CMD.new(name, t)
+	local dt = type(t)
+	local value
+	if dt == "table" then
+		value = t
+	elseif dt == "string" then
+		value = {}
+		local f = load(t, "=" .. name, "t", env)
+		f()
+	elseif dt == "nil" then
+		value = {}
+	else
+		error ("Unknown data type " .. dt)
+	end
+	newobj(name, value)
+end
+
+function CMD.delete(name)
+	local v = assert(pool[name])
+	pool[name] = nil
+	assert(objmap[v.obj])
+	objmap[v.obj] = true
+	sharedata.host.decref(v.obj)
+end
+
+function CMD.query(name)
+	local v = assert(pool[name])
+	local obj = v.obj
+	sharedata.host.incref(obj)
+	return v.obj
+end
+
+function CMD.confirm(cobj)
+	if objmap[cobj] then
+		sharedata.host.decref(cobj)
+	end
+	return NORET
+end
+
+function CMD.update(name, t)
+	local v = pool[name]
+	local watch, oldcobj
+	if v then
+		watch = v.watch
+		oldcobj = v.obj
+		CMD.delete(name)
+	end
+	CMD.new(name, t)
+	local newobj = pool[name].obj
+	if watch then
+		sharedata.host.markdirty(oldcobj)
+		for _,v in ipairs(watch) do
+			local session = v[1]
+			local address = v[2]
+			skynet.redirect(address, 0, "response", session, skynet.pack(newobj))
+		end
+	end
+end
+
+function CMD.monitor(session, address, name, obj)
+	local v = assert(pool[name])
+	if obj ~= v.obj then
+		return v.obj
+	end
+
+	table.insert(v.watch, { session, address })
+
+	return NORET
+end
+
+skynet.start(function()
+	skynet.fork(collectobj)
+	skynet.dispatch("lua", function (session, source ,cmd, ...)
+		local f = assert(CMD[cmd])
+		local r
+		if cmd == "monitor" then
+			r = f(session, source, ...)
+		else
+			r = f(...)
+		end
+		if r ~= NORET then
+			skynet.ret(skynet.pack(r))
+		end
+	end)
+end)
+