diff --git a/lib/resty/wasmx.lua b/lib/resty/wasmx.lua
index 9f71f75f2..e61da77c0 100644
--- a/lib/resty/wasmx.lua
+++ b/lib/resty/wasmx.lua
@@ -15,10 +15,14 @@ ffi.cdef [[
         ngx_str_t       *config;
     } ngx_wasm_filter_t;
 
+    typedef intptr_t                      ngx_int_t;
     typedef unsigned char                 u_char;
     typedef struct ngx_wavm_t             ngx_wasm_vm_t;
     typedef struct ngx_wasm_ops_plan_t    ngx_wasm_plan_t;
 
+    typedef ngx_int_t (*ngx_wasm_host_prop_fn_t)(void *data, ngx_str_t *key,
+        ngx_str_t *value);
+
     ngx_wasm_vm_t *ngx_wasm_ffi_main_vm();
 ]]
 
diff --git a/lib/resty/wasmx/proxy_wasm.lua b/lib/resty/wasmx/proxy_wasm.lua
index e44e727bf..b3310cb04 100644
--- a/lib/resty/wasmx/proxy_wasm.lua
+++ b/lib/resty/wasmx/proxy_wasm.lua
@@ -38,23 +38,25 @@ local _M = {
 
 if subsystem == "http" then
     ffi.cdef [[
-        int ngx_http_wasm_ffi_plan_new(ngx_wasm_vm_t *vm,
-                                       ngx_wasm_filter_t *filters,
-                                       size_t n_filters,
-                                       ngx_wasm_plan_t **out,
-                                       u_char *err, size_t *errlen);
-        int ngx_http_wasm_ffi_plan_free(ngx_wasm_plan_t *plan);
-        int ngx_http_wasm_ffi_plan_load(ngx_wasm_plan_t *plan);
-        int ngx_http_wasm_ffi_plan_attach(ngx_http_request_t *r,
-                                          ngx_wasm_plan_t *plan,
-                                          unsigned int isolation);
-        int ngx_http_wasm_ffi_start(ngx_http_request_t *r);
-        int ngx_http_wasm_ffi_set_property(ngx_http_request_t *r,
-                                           ngx_str_t *key,
-                                           ngx_str_t *value);
-        int ngx_http_wasm_ffi_get_property(ngx_http_request_t *r,
-                                           ngx_str_t *key,
-                                           ngx_str_t *out);
+        ngx_int_t ngx_http_wasm_ffi_plan_new(ngx_wasm_vm_t *vm,
+                                             ngx_wasm_filter_t *filters,
+                                             size_t n_filters,
+                                             ngx_wasm_plan_t **out,
+                                             u_char *err, size_t *errlen);
+        ngx_int_t ngx_http_wasm_ffi_plan_free(ngx_wasm_plan_t *plan);
+        ngx_int_t ngx_http_wasm_ffi_plan_load(ngx_wasm_plan_t *plan);
+        ngx_int_t ngx_http_wasm_ffi_plan_attach(ngx_http_request_t *r,
+                                                ngx_wasm_plan_t *plan,
+                                                unsigned int isolation);
+        ngx_int_t ngx_http_wasm_ffi_start(ngx_http_request_t *r);
+        ngx_int_t ngx_http_wasm_ffi_set_property(ngx_http_request_t *r,
+                                                 ngx_str_t *key,
+                                                 ngx_str_t *value);
+        ngx_int_t ngx_http_wasm_ffi_get_property(ngx_http_request_t *r,
+                                                 ngx_str_t *key,
+                                                 ngx_str_t *out);
+        ngx_int_t ngx_http_wasm_ffi_enable_property_setter(ngx_http_request_t *r);
+        ngx_int_t ngx_http_wasm_ffi_enable_property_getter(ngx_http_request_t *r);
     ]]
 
 else
@@ -229,7 +231,7 @@ function _M.set_property(key, value)
         error("key must be a string", 2)
     end
 
-    if type(value) ~= "string" then
+    if value ~= nil and type(value) ~= "string" then
         error("value must be a string", 2)
     end
 
@@ -238,8 +240,14 @@ function _M.set_property(key, value)
         error("no request found", 2)
     end
 
-    local ckey = ffi_new("ngx_str_t", { data = key, len = #key })
-    local cvalue = ffi_new("ngx_str_t", { data = value, len = #value })
+    local ckey = ffi_new("ngx_str_t", {
+        data = key,
+        len = #key
+    })
+    local cvalue = ffi_new("ngx_str_t", {
+        data = value,
+        len = value and #value or 0
+    })
 
     local rc = C.ngx_http_wasm_ffi_set_property(r, ckey, cvalue)
     if rc == FFI_ERROR then
@@ -276,8 +284,81 @@ function _M.get_property(key)
         return nil, "property \"" .. key .. "\" not found", NOT_FOUND
     end
 
+    if cvalue.data == nil then
+        return nil
+    end
+
     return ffi_str(cvalue.data, cvalue.len)
 end
 
 
+---
+-- Define a setter function for host-managed properties.
+--
+-- @param setter The setter function is the handler for updating properties.
+-- Its type signature is `function(string, string): boolean, string`,
+-- where the inputs are the property key and value and the results are:
+-- * `truthy` - success setting the property
+-- * `truthy, value` - success, cache property value (useful if hosts
+--   sets only a setter but not a getter)
+-- * `truthy, value, truthy` - success, constant property value: further
+--   requests to the same property during a request are cached by
+--   ngx_wasm_module and do not invoke the Lua getter.
+-- * `falsy, err` - failure, and an optional error message
+-- @return true on success setting the getter, or nil and an error message.
+function _M.set_property_setter(setter)
+    if type(setter) ~= "function" then
+        error("setter must be a function", 2)
+    end
+
+    local r = get_request()
+    if not r then
+        error("no request found", 2)
+    end
+
+    _M.property_setter = setter
+
+    local rc = C.ngx_http_wasm_ffi_enable_property_setter(r)
+    if rc ~= FFI_OK then
+        return nil, "could not set property setter"
+    end
+
+    return true
+end
+
+
+---
+-- Define a getter function for host-managed properties.
+--
+-- @param getter The getter function is the handler for resolving properties.
+-- Its type signature is `function(string): boolean, string, boolean`,
+-- where the input is the property key and the results are:
+-- * `truthy, value` - success, property value
+-- * `truthy, value, truthy` - success, constant property value: further
+--   requests to the same property during a request are cached by
+--   ngx_wasm_module and do not invoke the Lua getter.
+-- * `falsy` - property not found
+-- * `falsy, err` - failure, error message
+-- @return true on success setting the getter, or nil and an error message.
+function _M.set_property_getter(getter)
+    if type(getter) ~= "function" then
+        error("getter must be a function", 2)
+    end
+
+    local r = get_request()
+    if not r then
+        error("no request found", 2)
+    end
+
+    _M.property_getter = getter
+
+    local rc = C.ngx_http_wasm_ffi_enable_property_getter(r)
+    if rc ~= FFI_OK then
+        return nil, "could not set property getter"
+    end
+
+    return true
+end
+
+
 return _M
diff --git a/src/common/lua/ngx_wasm_lua.c b/src/common/lua/ngx_wasm_lua.c
index fc83c1ba7..11f8274c2 100644
--- a/src/common/lua/ngx_wasm_lua.c
+++ b/src/common/lua/ngx_wasm_lua.c
@@ -1,5 +1,5 @@
 #ifndef DDEBUG
-#define DDEBUG 0
+#define DDEBUG 1
 #endif
 #include "ddebug.h"
 
@@ -113,6 +113,56 @@ ngx_wasm_lua_thread_destroy(ngx_wasm_lua_ctx_t *lctx)
 }
 
 
+static ngx_int_t
+ngx_wasm_lua_load_code(ngx_wasm_lua_ctx_t *lctx,
+    const char *tag, const char *src,
+    ngx_wasm_subsys_env_t *env)
+{
+    ngx_int_t  rc;
+
+    lctx->code = src;
+    lctx->code_len = ngx_strlen(src);
+    lctx->cache_key = ngx_wasm_lua_thread_cache_key(lctx->pool,
+                                                    tag,
+                                                    (u_char *) lctx->code,
+                                                    lctx->code_len);
+    if (lctx->cache_key == NULL) {
+        return NGX_ERROR;
+    }
+
+    /* load code */
+
+    switch (env->subsys->kind) {
+#if (NGX_WASM_HTTP)
+    case NGX_WASM_SUBSYS_HTTP:
+        rc = ngx_http_lua_cache_loadbuffer(lctx->log,
+                                           lctx->L,
+                                           (u_char *) lctx->code,
+                                           lctx->code_len,
+                                           &lctx->code_ref,
+                                           lctx->cache_key,
+                                           tag);
+        break;
+#endif
+#if (NGX_WASM_STREAM)
+    case NGX_WASM_SUBSYS_STREAM:
+        rc = ngx_stream_lua_cache_loadbuffer(lctx->log,
+                                             lctx->L,
+                                             (u_char *) lctx->code,
+                                             lctx->code_len,
+                                             lctx->cache_key,
+                                             tag);
+        break;
+#endif
+    default:
+        ngx_wasm_assert(0);
+        return NGX_ERROR;
+    }
+
+    return rc;
+}
+
+
 ngx_wasm_lua_ctx_t *
 ngx_wasm_lua_thread_new(const char *tag, const char *src,
     ngx_wasm_subsys_env_t *env, ngx_log_t *log, void *data,
@@ -155,6 +205,9 @@ ngx_wasm_lua_thread_new(const char *tag, const char *src,
 
         lctx->L = ngx_http_lua_get_lua_vm(r, NULL);
         lctx->co = ngx_http_lua_new_thread(r, lctx->L, &lctx->co_ref);
+
+        ngx_http_lua_set_req(lctx->co, r);
+
         break;
     }
 #endif
@@ -166,6 +219,9 @@ ngx_wasm_lua_thread_new(const char *tag, const char *src,
 
         lctx->L = ngx_stream_lua_get_lua_vm(sr, NULL);
         lctx->co = ngx_stream_lua_new_thread(sr, lctx->L, lctx->co_ref);
+
+        ngx_stream_lua_set_req(lctx->co, sr);
+
         break;
     }
 #endif
@@ -183,47 +239,11 @@ ngx_wasm_lua_thread_new(const char *tag, const char *src,
 
     /* code */
 
-    lctx->code = src;
-    lctx->code_len = ngx_strlen(src);
-    lctx->cache_key = ngx_wasm_lua_thread_cache_key(lctx->pool,
-                                                    tag,
-                                                    (u_char *) lctx->code,
-                                                    lctx->code_len);
-    if (lctx->cache_key == NULL) {
-        goto error;
-    }
-
-    /* load code */
-
-    switch (env->subsys->kind) {
-#if (NGX_WASM_HTTP)
-    case NGX_WASM_SUBSYS_HTTP:
-        rc = ngx_http_lua_cache_loadbuffer(lctx->log,
-                                           lctx->L,
-                                           (u_char *) lctx->code,
-                                           lctx->code_len,
-                                           &lctx->code_ref,
-                                           lctx->cache_key,
-                                           tag);
-        break;
-#endif
-#if (NGX_WASM_STREAM)
-    case NGX_WASM_SUBSYS_STREAM:
-        rc = ngx_stream_lua_cache_loadbuffer(lctx->log,
-                                             lctx->L,
-                                             (u_char *) lctx->code,
-                                             lctx->code_len,
-                                             lctx->cache_key,
-                                             tag);
-        break;
-#endif
-    default:
-        ngx_wasm_assert(0);
-        goto error;
-    }
-
-    if (rc != NGX_OK) {
-        goto error;
+    if (src) {
+        rc = ngx_wasm_lua_load_code(lctx, tag, src, env);
+        if (rc != NGX_OK) {
+            goto error;
+        }
     }
 
     /*  move code closure to new coroutine  */
diff --git a/src/common/lua/ngx_wasm_lua_ffi.c b/src/common/lua/ngx_wasm_lua_ffi.c
index 0516a39b1..538edd2fc 100644
--- a/src/common/lua/ngx_wasm_lua_ffi.c
+++ b/src/common/lua/ngx_wasm_lua_ffi.c
@@ -3,6 +3,7 @@
 #endif
 #include "ddebug.h"
 
+#include <ngx_wasm_lua.h>
 #include <ngx_wasm_lua_ffi.h>
 
 
@@ -180,6 +181,21 @@ ngx_http_wasm_ffi_start(ngx_http_request_t *r)
 }
 
 
+static ngx_inline ngx_proxy_wasm_ctx_t *
+get_pwctx(ngx_http_request_t *r)
+{
+    ngx_http_wasm_req_ctx_t  *rctx;
+
+    if (ngx_http_wasm_rctx(r, &rctx) != NGX_OK) {
+        return NULL;
+    }
+
+    return ngx_proxy_wasm_ctx(NULL, 0,
+                              NGX_PROXY_WASM_ISOLATION_STREAM,
+                              &ngx_http_proxy_wasm, rctx);
+}
+
+
 ngx_int_t
 ngx_http_wasm_ffi_set_property(ngx_http_request_t *r,
     ngx_str_t *key, ngx_str_t *value)
@@ -226,4 +242,206 @@ ngx_http_wasm_ffi_get_property(ngx_http_request_t *r,
 
     return ngx_proxy_wasm_properties_get(pwctx, key, value);
 }
+
+
+void
+ngx_wasm_lua_ffi_host_prop_handler(
+    ngx_wasm_ffi_host_property_ctx_t *hpctx,
+    unsigned char ok, const char* new_value, size_t len,
+    unsigned char is_const)
+{
+    ngx_proxy_wasm_ctx_t  *pwctx = get_pwctx(hpctx->r);
+    ngx_str_t             *key = hpctx->key;
+    ngx_str_t             *value = hpctx->value;
+
+    if (!ok) {
+        if (new_value) {
+            ngx_wavm_log_error(NGX_LOG_ERR, pwctx->log, NULL,
+                               "error in property handler: %s",
+                               new_value);
+            hpctx->rc = NGX_ERROR;
+            return;
+
+        } else if (!hpctx->is_getter) {
+            ngx_wavm_log_error(NGX_LOG_ERR, pwctx->log, NULL,
+                               "error in property handler: unknown error");
+            hpctx->rc = NGX_ERROR;
+            return;
+        }
+
+        hpctx->rc = NGX_DECLINED;
+        return;
+    }
+
+    if (new_value == NULL) {
+        value->data = NULL;
+        value->len = 0;
+
+    } else {
+        value->data = (u_char *) new_value;
+        value->len = len;
+    }
+
+    hpctx->rc = ngx_proxy_wasm_properties_set_host(pwctx, key, value, is_const,
+                                                    hpctx->is_getter);
+
+    if (hpctx->is_getter && hpctx->rc == NGX_OK && value->data == NULL) {
+        hpctx->rc = NGX_DECLINED;
+    }
+
+    hpctx->rc = NGX_OK;
+}
+
+static const char  *HOST_PROPERTY_SCRIPT_NAME = "wasm_lua_host_property_chunk";
+static const char  *HOST_PROPERTY_SCRIPT = ""
+    "local hpctx, is_getter, key, value = ...                             \n"
+    "local ffi = require('ffi')                                           \n"
+    "local fmt = string.format                                            \n"
+    "                                                                     \n"
+    "ffi.cdef[[                                                           \n"
+    "    typedef unsigned char  u_char;                                   \n"
+    "    typedef void           ngx_wasm_ffi_host_property_ctx_t;         \n"
+    "                                                                     \n"
+    "    void ngx_wasm_lua_ffi_host_prop_handler(                         \n"
+    "        ngx_wasm_ffi_host_property_ctx_t *hpctx,                     \n"
+    "        u_char ok, const char* value, size_t len,                    \n"
+    "        u_char is_const);                                            \n"
+    "]]                                                                   \n"
+    "                                                                     \n"
+    "local proxy_wasm = require('resty.wasmx.proxy_wasm')                 \n"
+    "                                                                     \n"
+    "local fn_name = is_getter and 'property_getter' or 'property_setter' \n"
+    "local fn = proxy_wasm[fn_name]                                       \n"
+    "if not fn then                                                       \n"
+    "    error('property handler function not found')                     \n"
+    "end                                                                  \n"
+    "                                                                     \n"
+    "local pok, ok, new_value, is_const = pcall(fn, key, value)           \n"
+    "if not pok then                                                      \n"
+    "    ngx.log(ngx.ERR, 'Lua error in property handler: ' .. ok)        \n"
+    "    error('fail')                                                    \n"
+    "end                                                                  \n"
+    "                                                                     \n"
+    "local new_value_len = new_value and #new_value or 0                  \n"
+    "                                                                     \n"
+    "ffi.C.ngx_wasm_lua_ffi_host_prop_handler(hpctx, ok and 1 or 0,       \n"
+    "                                         new_value, new_value_len,   \n"
+    "                                         is_const and 1 or 0)        \n";
+
+static ngx_int_t
+property_handler(ngx_proxy_wasm_ctx_t* pwctx, ngx_str_t *key, ngx_str_t *value,
+    unsigned is_getter)
+{
+    ngx_http_wasm_req_ctx_t               *rctx = pwctx->data;
+    ngx_wasm_ffi_host_property_ctx_t       hpctx;
+    lua_State                             *co;
+    ngx_wasm_lua_ctx_t                    *lctx;
+    int                                    rv;
+
+    // FIXME if this function is changed to return NGX_AGAIN,
+    // hpctx needs to be dynamically allocated:
+
+    hpctx.r = rctx->r;
+    hpctx.is_getter = is_getter;
+    hpctx.key = key;
+    hpctx.value = value;
+
+    /* create coroutine */
+
+    lctx = ngx_wasm_lua_thread_new(HOST_PROPERTY_SCRIPT_NAME,
+                                   HOST_PROPERTY_SCRIPT,
+                                   &rctx->env, rctx->r->connection->log, &hpctx,
+                                   NULL, NULL);
+    if (lctx == NULL) {
+        return NGX_ERROR;
+    }
+
+    /* push key and value arguments */
+
+    co = lctx->co;
+
+    ngx_wasm_assert(key && key->data);
+    ngx_wasm_assert(value);
+
+    lctx->nargs = 4;
+
+    lua_pushlightuserdata(co, &hpctx);
+    lua_pushboolean(co, is_getter);
+    lua_pushlstring(co, (char *) key->data, key->len);
+
+    if (is_getter || value->data == NULL) {
+        lua_pushnil(co);
+
+    } else {
+        if ((int) value->len == 0) {
+            lua_pushliteral(co, "");
+
+        } else {
+            lua_pushlstring(co, (char *) value->data, value->len);
+        }
+    }
+
+    /* run handler */
+
+    rv = lua_resume(lctx->co, lctx->nargs);
+    if (rv == LUA_YIELD) {
+        ngx_wavm_log_error(NGX_LOG_ERR, pwctx->log, NULL,
+        "cannot yield from host property handler");
+
+        return NGX_ERROR;
+    }
+
+    if (rv != 0) {
+        ngx_wavm_log_error(NGX_LOG_ERR, pwctx->log, NULL,
+        "Lua resume failed with error: code %d", rv);
+
+        return NGX_ERROR;
+    }
+
+    return hpctx.rc;
+}
+
+
+static ngx_int_t
+property_setter(void* pwctx, ngx_str_t *key, ngx_str_t *value)
+{
+    return property_handler((ngx_proxy_wasm_ctx_t *) pwctx, key, value, 0);
+}
+
+
+static ngx_int_t
+property_getter(void* pwctx, ngx_str_t *key, ngx_str_t *value)
+{
+    return property_handler((ngx_proxy_wasm_ctx_t *) pwctx, key, value, 1);
+}
+
+
+ngx_int_t
+ngx_http_wasm_ffi_enable_property_setter(ngx_http_request_t *r)
+{
+    ngx_proxy_wasm_ctx_t  *pwctx = get_pwctx(r);
+
+    if (pwctx == NULL) {
+        return NGX_ERROR;
+    }
+
+    return ngx_proxy_wasm_properties_set_host_prop_setter(pwctx,
+                                                          property_setter,
+                                                          pwctx);
+}
+
+
+ngx_int_t
+ngx_http_wasm_ffi_enable_property_getter(ngx_http_request_t *r)
+{
+    ngx_proxy_wasm_ctx_t  *pwctx = get_pwctx(r);
+
+    if (pwctx == NULL) {
+        return NGX_ERROR;
+    }
+
+    return ngx_proxy_wasm_properties_set_host_prop_getter(pwctx,
+                                                          property_getter,
+                                                          pwctx);
+}
 #endif
diff --git a/src/common/lua/ngx_wasm_lua_ffi.h b/src/common/lua/ngx_wasm_lua_ffi.h
index 0178058e1..9d9808da7 100644
--- a/src/common/lua/ngx_wasm_lua_ffi.h
+++ b/src/common/lua/ngx_wasm_lua_ffi.h
@@ -21,6 +21,15 @@ typedef struct {
 } ngx_wasm_ffi_filter_t;
 
 
+typedef struct {
+    ngx_http_request_t  *r;
+    unsigned             is_getter;
+    ngx_str_t           *key;
+    ngx_str_t           *value;
+    ngx_int_t            rc;
+} ngx_wasm_ffi_host_property_ctx_t;
+
+
 ngx_int_t ngx_http_wasm_ffi_plan_new(ngx_wavm_t *vm,
     ngx_wasm_ffi_filter_t *filters, size_t n_filters,
     ngx_wasm_ops_plan_t **out, u_char *err, size_t *errlen);
@@ -33,6 +42,12 @@ ngx_int_t ngx_http_wasm_ffi_set_property(ngx_http_request_t *r,
     ngx_str_t *key, ngx_str_t *value);
 ngx_int_t ngx_http_wasm_ffi_get_property(ngx_http_request_t *r,
     ngx_str_t *key, ngx_str_t *value);
+ngx_int_t ngx_http_wasm_ffi_set_host_property(ngx_http_request_t *r,
+    ngx_str_t *key, ngx_str_t *value, unsigned is_const, unsigned retrieve);
+ngx_int_t ngx_http_wasm_ffi_set_property_setter(ngx_http_request_t *r,
+    ngx_wasm_host_prop_fn_t fn);
+ngx_int_t ngx_http_wasm_ffi_set_property_getter(ngx_http_request_t *r,
+    ngx_wasm_host_prop_fn_t fn);
 #endif
 
 
diff --git a/src/common/proxy_wasm/ngx_proxy_wasm.h b/src/common/proxy_wasm/ngx_proxy_wasm.h
index 772508676..4c2877244 100644
--- a/src/common/proxy_wasm/ngx_proxy_wasm.h
+++ b/src/common/proxy_wasm/ngx_proxy_wasm.h
@@ -166,6 +166,9 @@ typedef struct ngx_http_proxy_wasm_dispatch_s  ngx_http_proxy_wasm_dispatch_t;
 
 typedef ngx_str_t  ngx_proxy_wasm_marshalled_map_t;
 
+typedef ngx_int_t (*ngx_wasm_host_prop_fn_t)(void *data, ngx_str_t *key,
+    ngx_str_t *value);
+
 
 typedef struct {
     ngx_queue_t                        busy;
@@ -245,10 +248,14 @@ struct ngx_proxy_wasm_ctx_s {
     ngx_uint_t                         call_code;
     ngx_uint_t                         response_code;
 
-    /* host properties rbtree */
+    /* host properties */
 
     ngx_rbtree_t                       host_props_tree;
     ngx_rbtree_node_t                  host_props_sentinel;
+    ngx_wasm_host_prop_fn_t            host_prop_getter;
+    ngx_wasm_host_prop_fn_t            host_prop_setter;
+    void                              *host_prop_getter_data;
+    void                              *host_prop_setter_data;
 
     /* flags */
 
diff --git a/src/common/proxy_wasm/ngx_proxy_wasm_properties.c b/src/common/proxy_wasm/ngx_proxy_wasm_properties.c
index 6af10b3e3..333688722 100644
--- a/src/common/proxy_wasm/ngx_proxy_wasm_properties.c
+++ b/src/common/proxy_wasm/ngx_proxy_wasm_properties.c
@@ -53,6 +53,8 @@ static size_t       host_prefix_len;
 typedef struct {
     ngx_str_node_t  sn;
     ngx_str_t       value;
+    unsigned        is_const:1;
+    unsigned        const_null:1;
 } host_props_node_t;
 
 
@@ -877,25 +879,58 @@ ngx_proxy_wasm_properties_get_host(ngx_proxy_wasm_ctx_t *pwctx,
 
     hpn = (host_props_node_t *)
               ngx_str_rbtree_lookup(&pwctx->host_props_tree, path, hash);
+    if (hpn == NULL) {
+        return NGX_DECLINED;
+    }
 
-    if (hpn) {
-        value->data = hpn->value.data;
-        value->len = hpn->value.len;
+    /* stored value is not const: need to call getter again */
+    if (!hpn->is_const && pwctx->host_prop_getter) {
+        return NGX_DECLINED;
+    }
 
-        return NGX_OK;
+    if (hpn->const_null) {
+        return NGX_BUSY;
     }
 
-    return NGX_DECLINED;
+    value->data = hpn->value.data;
+    value->len = hpn->value.len;
+
+    return NGX_OK;
 }
 
 
-static ngx_int_t
+static ngx_inline ngx_int_t
+set_hpn_value(host_props_node_t *hpn, ngx_str_t *value, unsigned is_const,
+    ngx_pool_t *pool)
+{
+    unsigned char  *new_data;
+
+    if (value->data == NULL) {
+        new_data = NULL;
+        hpn->const_null = 1;
+
+    } else {
+        new_data = ngx_pstrdup(pool, value);
+        if (new_data == NULL) {
+            return NGX_ERROR;
+        }
+    }
+
+    hpn->is_const = is_const;
+    hpn->value.len = value->len;
+    hpn->value.data = new_data;
+
+    return NGX_OK;
+}
+
+
+ngx_int_t
 ngx_proxy_wasm_properties_set_host(ngx_proxy_wasm_ctx_t *pwctx,
-    ngx_str_t *path, ngx_str_t *value)
+    ngx_str_t *path, ngx_str_t *value, unsigned is_const, unsigned retrieve)
 {
     host_props_node_t        *hpn;
     uint32_t                  hash;
-    unsigned                  new_entry = 1;
+    ngx_int_t                 rc;
 #ifdef NGX_WASM_HTTP
     ngx_http_wasm_req_ctx_t  *rctx = pwctx->data;
 
@@ -911,8 +946,17 @@ ngx_proxy_wasm_properties_set_host(ngx_proxy_wasm_ctx_t *pwctx,
     hpn = (host_props_node_t *)
               ngx_str_rbtree_lookup(&pwctx->host_props_tree, path, hash);
 
-    if (value->data == NULL) {
+    if (hpn && hpn->is_const) {
+        /* if a const node exists, we can't overwrite it */
+
+        return NGX_DECLINED;
+    }
+
+    if (value->data == NULL && !is_const) {
+        /* if setting non-const NULL, remove node if it exists */
+
         if (hpn) {
+            ngx_pfree(pwctx->pool, hpn->value.data);
             ngx_rbtree_delete(&pwctx->host_props_tree, &hpn->sn.node);
         }
 
@@ -920,10 +964,18 @@ ngx_proxy_wasm_properties_set_host(ngx_proxy_wasm_ctx_t *pwctx,
     }
 
     if (hpn) {
+        /* if the node exists, replace the value */
+
         ngx_pfree(pwctx->pool, hpn->value.data);
-        new_entry = 0;
+        rc = set_hpn_value(hpn, value, is_const, pwctx->pool);
+        if (rc != NGX_OK) {
+            return rc;
+        }
 
     } else {
+        /* if the node doesn't exist,
+           create it, set key, value, and store node in rbtree */
+
         hpn = ngx_pcalloc(pwctx->pool, sizeof(host_props_node_t) + path->len);
         if (hpn == NULL) {
             return NGX_ERROR;
@@ -933,18 +985,19 @@ ngx_proxy_wasm_properties_set_host(ngx_proxy_wasm_ctx_t *pwctx,
         hpn->sn.str.len = path->len;
         hpn->sn.str.data = (u_char *) hpn + sizeof(host_props_node_t);
         ngx_memcpy(hpn->sn.str.data, path->data, path->len);
-    }
 
-    hpn->value.len = value->len;
-    hpn->value.data = ngx_pstrdup(pwctx->pool, value);
-    if (hpn->value.data == NULL) {
-        return NGX_ERROR;
-    }
+        rc = set_hpn_value(hpn, value, is_const, pwctx->pool);
+        if (rc != NGX_OK) {
+            return rc;
+        }
 
-    if (new_entry) {
         ngx_rbtree_insert(&pwctx->host_props_tree, &hpn->sn.node);
     }
 
+    if (retrieve) {
+        value->data = hpn->value.data;
+    }
+
     return NGX_OK;
 }
 
@@ -970,6 +1023,7 @@ ngx_proxy_wasm_properties_get(ngx_proxy_wasm_ctx_t *pwctx,
     ngx_str_t           p = { path->len, NULL };
     ngx_uint_t          key;
     pwm2ngx_mapping_t  *m;
+    ngx_int_t           rc;
 
     p.data = replace_nulls_by_dots(path, dotted_path_buf);
     key = ngx_hash_key(p.data, p.len);
@@ -997,7 +1051,22 @@ ngx_proxy_wasm_properties_get(ngx_proxy_wasm_ctx_t *pwctx,
         && ngx_memcmp(p.data, host_prefix, host_prefix_len) == 0)
     {
         /* host variable */
-        return ngx_proxy_wasm_properties_get_host(pwctx, &p, value);
+
+        /* even if there is a getter, try reading const value first */
+        rc = ngx_proxy_wasm_properties_get_host(pwctx, &p, value);
+        if (rc == NGX_OK) {
+            return NGX_OK;
+
+        } else if (rc == NGX_BUSY) {
+            return NGX_DECLINED;
+        }
+
+        if (pwctx->host_prop_getter) {
+            return pwctx->host_prop_getter(pwctx->host_prop_getter_data,
+                                           &p, value);
+        }
+
+        return rc;
     }
 
     return NGX_DECLINED;
@@ -1033,8 +1102,57 @@ ngx_proxy_wasm_properties_set(ngx_proxy_wasm_ctx_t *pwctx,
         && ngx_memcmp(p.data, host_prefix, host_prefix_len) == 0)
     {
         /* host variable */
-        return ngx_proxy_wasm_properties_set_host(pwctx, &p, value);
+        if (pwctx->host_prop_setter) {
+            return pwctx->host_prop_setter(pwctx->host_prop_setter_data,
+                                           &p, value);
+        }
+
+        return ngx_proxy_wasm_properties_set_host(pwctx, &p, value, 0, 0);
     }
 
     return NGX_DECLINED;
 }
+
+
+ngx_int_t
+ngx_proxy_wasm_properties_set_host_prop_setter(ngx_proxy_wasm_ctx_t *pwctx,
+    ngx_wasm_host_prop_fn_t fn, void *data)
+{
+#ifdef NGX_WASM_HTTP
+    ngx_http_wasm_req_ctx_t  *rctx = pwctx->data;
+
+    if (rctx == NULL || rctx->fake_request) {
+        ngx_wavm_log_error(NGX_LOG_ERR, pwctx->log, NULL,
+                           "cannot set host properties setter "
+                           "outside of a request");
+        return NGX_ERROR;
+    }
+#endif
+
+    pwctx->host_prop_setter = fn;
+    pwctx->host_prop_setter_data = data;
+
+    return NGX_OK;
+}
+
+
+ngx_int_t
+ngx_proxy_wasm_properties_set_host_prop_getter(ngx_proxy_wasm_ctx_t *pwctx,
+    ngx_wasm_host_prop_fn_t fn, void *data)
+{
+#ifdef NGX_WASM_HTTP
+    ngx_http_wasm_req_ctx_t  *rctx = pwctx->data;
+
+    if (rctx == NULL || rctx->fake_request) {
+        ngx_wavm_log_error(NGX_LOG_ERR, pwctx->log, NULL,
+                           "cannot set host properties getter "
+                           "outside of a request");
+        return NGX_ERROR;
+    }
+#endif
+
+    pwctx->host_prop_getter = fn;
+    pwctx->host_prop_getter_data = data;
+
+    return NGX_OK;
+}
diff --git a/src/common/proxy_wasm/ngx_proxy_wasm_properties.h b/src/common/proxy_wasm/ngx_proxy_wasm_properties.h
index e39438cfa..9843fd229 100644
--- a/src/common/proxy_wasm/ngx_proxy_wasm_properties.h
+++ b/src/common/proxy_wasm/ngx_proxy_wasm_properties.h
@@ -9,6 +9,12 @@ ngx_int_t ngx_proxy_wasm_properties_get(ngx_proxy_wasm_ctx_t *pwctx,
     ngx_str_t *path, ngx_str_t *value);
 ngx_int_t ngx_proxy_wasm_properties_set(ngx_proxy_wasm_ctx_t *pwctx,
     ngx_str_t *path, ngx_str_t *value);
+ngx_int_t ngx_proxy_wasm_properties_set_host(ngx_proxy_wasm_ctx_t *pwctx,
+    ngx_str_t *path, ngx_str_t *value, unsigned is_const, unsigned retrieve);
+ngx_int_t ngx_proxy_wasm_properties_set_host_prop_setter(
+    ngx_proxy_wasm_ctx_t *pwctx, ngx_wasm_host_prop_fn_t fn, void *data);
+ngx_int_t ngx_proxy_wasm_properties_set_host_prop_getter(
+    ngx_proxy_wasm_ctx_t *pwctx, ngx_wasm_host_prop_fn_t fn, void *data);
 
 
 #endif /* _NGX_PROXY_WASM_PROPERTIES_H_INCLUDED_ */
diff --git a/t/04-openresty/ffi/304-proxy_wasm_set_property_getter.t b/t/04-openresty/ffi/304-proxy_wasm_set_property_getter.t
new file mode 100644
index 000000000..ac8f8786b
--- /dev/null
+++ b/t/04-openresty/ffi/304-proxy_wasm_set_property_getter.t
@@ -0,0 +1,597 @@
+# vim:set ft= ts=4 sw=4 et fdm=marker:
+
+use strict;
+use lib '.';
+use t::TestWasm::Lua;
+
+skip_no_openresty();
+
+plan tests => repeat_each() * (blocks() * 5);
+
+run_tests();
+
+__DATA__
+
+=== TEST 1: set_property_getter() - setting host properties getter fails on init_worker_by_lua
+--- wasm_modules: on_phases
+--- http_config
+    init_worker_by_lua_block {
+        local proxy_wasm = require "resty.wasmx.proxy_wasm"
+        local filters = {
+            { name = "on_phases" },
+        }
+
+        _G.c_plan = assert(proxy_wasm.new(filters))
+        assert(proxy_wasm.load(_G.c_plan))
+
+        local function getter(key)
+            if key == "my_key" then
+                return true, "my_value"
+            end
+            return false
+        end
+
+        assert(proxy_wasm.set_property_getter(getter))
+    }
+--- config
+    location /t {
+        rewrite_by_lua_block {
+            ngx.say("ok")
+        }
+    }
+--- response_body
+ok
+--- error_log eval
+[
+    qr/\[error\] .*? cannot set host properties getter outside of a request/,
+    qr/\[error\] .*? init_worker_by_lua(\(nginx\.conf:\d+\))?:\d+: could not set property getter/,
+]
+--- no_error_log
+[crit]
+
+
+
+=== TEST 2: set_property_getter() - setting host properties getter works on rewrite_by_lua
+--- wasm_modules: hostcalls
+--- http_config
+    init_worker_by_lua_block {
+        local proxy_wasm = require "resty.wasmx.proxy_wasm"
+        local filters = {
+            { name = "hostcalls" },
+        }
+
+        _G.c_plan = assert(proxy_wasm.new(filters))
+        assert(proxy_wasm.load(_G.c_plan))
+    }
+--- config
+    location /t {
+        proxy_wasm hostcalls 'on=response_body \
+                              test=/t/log/property \
+                              name=wasmx.my_property';
+
+        rewrite_by_lua_block {
+            local proxy_wasm = require "resty.wasmx.proxy_wasm"
+            assert(proxy_wasm.attach(_G.c_plan))
+
+            local function getter(key)
+                if key == "wasmx.my_property" then
+                    return true, "my_value"
+                end
+                return false
+            end
+
+            assert(proxy_wasm.set_property_getter(getter))
+
+            assert(proxy_wasm.start())
+            ngx.say("ok")
+        }
+    }
+--- response_body
+ok
+--- error_log eval
+[
+    qr/\[info\] .*? \[hostcalls\] on_response_body/,
+    qr/\[info\] .*? wasmx.my_property: my_value/,
+]
+--- no_error_log
+[error]
+
+
+
+=== TEST 3: set_property_getter() - setting host properties getter works on access_by_lua
+--- wasm_modules: hostcalls
+--- http_config
+    init_worker_by_lua_block {
+        local proxy_wasm = require "resty.wasmx.proxy_wasm"
+        local filters = {
+            { name = "hostcalls" },
+        }
+
+        _G.c_plan = assert(proxy_wasm.new(filters))
+        assert(proxy_wasm.load(_G.c_plan))
+    }
+--- config
+    location /t {
+        proxy_wasm hostcalls 'on=response_body \
+                              test=/t/log/property \
+                              name=wasmx.my_property';
+
+        access_by_lua_block {
+            local proxy_wasm = require "resty.wasmx.proxy_wasm"
+            assert(proxy_wasm.attach(_G.c_plan))
+
+            local function getter(key)
+                if key == "wasmx.my_property" then
+                    return true, "my_value"
+                end
+                return false
+            end
+
+            assert(proxy_wasm.set_property_getter(getter))
+
+            assert(proxy_wasm.start())
+            ngx.say("ok")
+        }
+    }
+--- response_body
+ok
+--- error_log eval
+[
+    qr/\[info\] .*? \[hostcalls\] on_response_body/,
+    qr/\[info\] .*? wasmx.my_property: my_value/,
+]
+--- no_error_log
+[error]
+
+
+
+=== TEST 4: set_property_getter() - setting host properties getter works on header_filter_by_lua
+--- wasm_modules: hostcalls
+--- http_config
+    init_worker_by_lua_block {
+        local proxy_wasm = require "resty.wasmx.proxy_wasm"
+        local filters = {
+            { name = "hostcalls" },
+        }
+
+        _G.c_plan = assert(proxy_wasm.new(filters))
+        assert(proxy_wasm.load(_G.c_plan))
+    }
+--- config
+    location /t {
+        proxy_wasm hostcalls 'on=response_body \
+                              test=/t/log/property \
+                              name=wasmx.my_property';
+
+        rewrite_by_lua_block {
+            local proxy_wasm = require "resty.wasmx.proxy_wasm"
+            assert(proxy_wasm.attach(_G.c_plan))
+
+            assert(proxy_wasm.start())
+            ngx.say("ok")
+        }
+
+        header_filter_by_lua_block {
+            local proxy_wasm = require "resty.wasmx.proxy_wasm"
+
+            local function getter(key)
+                if key == "wasmx.my_property" then
+                    return true, "my_value"
+                end
+                return false
+            end
+
+            assert(proxy_wasm.set_property_getter(getter))
+        }
+    }
+--- response_body
+ok
+--- error_log eval
+[
+    qr/\[info\] .*? \[hostcalls\] on_response_body/,
+    qr/\[info\] .*? wasmx.my_property: my_value/,
+]
+--- no_error_log
+[error]
+
+
+
+=== TEST 5: set_property_getter() - setting host properties getter works on body_filter_by_lua
+--- wasm_modules: hostcalls
+--- http_config
+    init_worker_by_lua_block {
+        local proxy_wasm = require "resty.wasmx.proxy_wasm"
+        local filters = {
+            { name = "hostcalls" },
+        }
+
+        _G.c_plan = assert(proxy_wasm.new(filters))
+        assert(proxy_wasm.load(_G.c_plan))
+    }
+--- config
+    location /t {
+        proxy_wasm hostcalls 'on=response_body \
+                              test=/t/log/property \
+                              name=wasmx.my_property';
+
+        rewrite_by_lua_block {
+            local proxy_wasm = require "resty.wasmx.proxy_wasm"
+            assert(proxy_wasm.attach(_G.c_plan))
+
+            assert(proxy_wasm.start())
+            ngx.say("ok")
+        }
+
+        body_filter_by_lua_block {
+            local proxy_wasm = require "resty.wasmx.proxy_wasm"
+
+            local function getter(key)
+                if key == "wasmx.my_property" then
+                    return true, "my_value"
+                end
+                return false
+            end
+
+            assert(proxy_wasm.set_property_getter(getter))
+        }
+    }
+--- response_body
+ok
+--- error_log eval
+[
+    qr/\[info\] .*? \[hostcalls\] on_response_body/,
+    qr/\[info\] .*? wasmx.my_property: my_value/,
+]
+--- no_error_log
+[error]
+
+
+
+=== TEST 6: set_property_getter() - setting host properties getter works on log_by_lua
+--- wasm_modules: hostcalls
+--- http_config
+    init_worker_by_lua_block {
+        local proxy_wasm = require "resty.wasmx.proxy_wasm"
+        local filters = {
+            { name = "hostcalls" },
+        }
+
+        _G.c_plan = assert(proxy_wasm.new(filters))
+        assert(proxy_wasm.load(_G.c_plan))
+    }
+--- config
+    location /t {
+        proxy_wasm_request_headers_in_access on;
+
+        proxy_wasm hostcalls 'on=log \
+                              test=/t/log/property \
+                              name=wasmx.my_property';
+
+        access_by_lua_block {
+            local proxy_wasm = require "resty.wasmx.proxy_wasm"
+            assert(proxy_wasm.attach(_G.c_plan))
+
+            assert(proxy_wasm.start())
+            ngx.say("ok")
+        }
+
+        log_by_lua_block {
+            local proxy_wasm = require "resty.wasmx.proxy_wasm"
+
+            local function getter(key)
+                if key == "wasmx.my_property" then
+                    return true, "my_value"
+                end
+                return false
+            end
+
+            assert(proxy_wasm.set_property_getter(getter))
+        }
+    }
+--- response_body
+ok
+--- error_log eval
+[
+    qr/\[info\] .*? \[hostcalls\] on_log/,
+    qr/\[info\] .*? wasmx.my_property: my_value/,
+]
+--- no_error_log
+[error]
+
+
+
+=== TEST 7: set_property_getter() - setting property getter at startup doesn't reset filter list
+--- wasm_modules: hostcalls
+--- http_config
+    init_worker_by_lua_block {
+        local proxy_wasm = require "resty.wasmx.proxy_wasm"
+        local filters = {
+            { name = "hostcalls", config = "on=log " ..
+                                           "test=/t/log/property " ..
+                                           "name=wasmx.startup_property" },
+        }
+
+        _G.c_plan = assert(proxy_wasm.new(filters))
+
+        assert(proxy_wasm.load(_G.c_plan))
+    }
+--- config
+    location /t {
+        proxy_wasm_request_headers_in_access on;
+
+        access_by_lua_block {
+            local proxy_wasm = require "resty.wasmx.proxy_wasm"
+
+            assert(proxy_wasm.attach(_G.c_plan))
+
+            local function getter(key)
+                if key == "wasmx.startup_property" then
+                    return true, "foo"
+                end
+                return false
+            end
+
+            assert(proxy_wasm.set_property_getter(getter))
+
+            assert(proxy_wasm.start())
+
+            ngx.say("ok")
+        }
+    }
+--- response_body
+ok
+--- error_log eval
+[
+    qr/\[info\] .*? \[hostcalls\] on_log/,
+    qr/\[info\] .*?hostcalls.*? wasmx.startup_property: foo/,
+]
+--- no_error_log
+[error]
+
+
+
+=== TEST 8: set_property_getter() - getter returning false produces property not found
+--- wasm_modules: hostcalls
+--- http_config
+    init_worker_by_lua_block {
+        local proxy_wasm = require "resty.wasmx.proxy_wasm"
+        local filters = {
+            { name = "hostcalls" },
+        }
+
+        _G.c_plan = assert(proxy_wasm.new(filters))
+        assert(proxy_wasm.load(_G.c_plan))
+    }
+--- config
+    location /t {
+        proxy_wasm hostcalls 'on=response_body \
+                              test=/t/log/property \
+                              name=wasmx.missing_property';
+
+        access_by_lua_block {
+            local proxy_wasm = require "resty.wasmx.proxy_wasm"
+            assert(proxy_wasm.attach(_G.c_plan))
+
+            local function getter(key)
+                if key == "wasmx.my_property" then
+                    return true, "my_value"
+                end
+                return false
+            end
+
+            assert(proxy_wasm.set_property_getter(getter))
+
+            assert(proxy_wasm.start())
+            ngx.say("ok")
+        }
+    }
+--- response_body
+ok
+--- error_log eval
+[
+    qr/\[info\] .*? \[hostcalls\] on_response_body/,
+    qr/\[info\] .*? property not found: wasmx.missing_property/,
+]
+--- no_error_log
+[error]
+
+
+
+=== TEST 9: set_property_getter() - getter returning nil produces property not found
+--- wasm_modules: hostcalls
+--- http_config
+    init_worker_by_lua_block {
+        local proxy_wasm = require "resty.wasmx.proxy_wasm"
+        local filters = {
+            { name = "hostcalls" },
+        }
+
+        _G.c_plan = assert(proxy_wasm.new(filters))
+        assert(proxy_wasm.load(_G.c_plan))
+    }
+--- config
+    location /t {
+        proxy_wasm hostcalls 'on=response_body \
+                              test=/t/log/property \
+                              name=wasmx.missing_property';
+
+        access_by_lua_block {
+            local proxy_wasm = require "resty.wasmx.proxy_wasm"
+            assert(proxy_wasm.attach(_G.c_plan))
+
+            local function getter(key)
+                if key == "wasmx.my_property" then
+                    return true, "my_value"
+                end
+            end
+
+            assert(proxy_wasm.set_property_getter(getter))
+
+            assert(proxy_wasm.start())
+            ngx.say("ok")
+        }
+    }
+--- response_body
+ok
+--- error_log eval
+[
+    qr/\[info\] .*? \[hostcalls\] on_response_body/,
+    qr/\[info\] .*? property not found: wasmx.missing_property/,
+]
+--- no_error_log
+[error]
+
+
+
+=== TEST 10: set_property_getter() - getter returning true on 3rd value caches result
+--- wasm_modules: hostcalls
+--- http_config
+    init_worker_by_lua_block {
+        local proxy_wasm = require "resty.wasmx.proxy_wasm"
+        local filters = {
+            { name = "hostcalls" },
+        }
+
+        _G.c_plan = assert(proxy_wasm.new(filters))
+        assert(proxy_wasm.load(_G.c_plan))
+    }
+--- config
+    location /t {
+        access_by_lua_block {
+            local proxy_wasm = require "resty.wasmx.proxy_wasm"
+            assert(proxy_wasm.attach(_G.c_plan))
+
+            local counter = 0
+
+            local function getter(key)
+                counter = counter + 1
+
+                ngx.log(ngx.INFO, "getting ", key, ", counter: ",
+                        tostring(counter))
+
+                if key == "wasmx.dyn_property" then
+                    return true, tostring(counter)
+
+                elseif key == "wasmx.const_property" then
+                    return true, tostring(counter), true
+
+                elseif key == "wasmx.nil_dyn_property" then
+                    return true, nil
+
+                elseif key == "wasmx.nil_const_property" then
+                    return true, nil, true
+
+                elseif key == "wasmx.empty_dyn_property" then
+                    return true, ""
+
+                elseif key == "wasmx.empty_const_property" then
+                    return true, "", true
+                end
+            end
+
+            assert(proxy_wasm.set_property_getter(getter))
+
+            assert(proxy_wasm.start())
+            ngx.say("ok")
+        }
+
+        log_by_lua_block {
+            local proxy_wasm = require "resty.wasmx.proxy_wasm"
+
+            local function log_property(k)
+                local v = proxy_wasm.get_property(k)
+                ngx.log(ngx.INFO, k, ": ", type(v), " \"", v, "\"")
+            end
+
+            -- four get_property operations,
+            -- but it will hit the getter three times
+            -- because the second call to get wasmx.const_property
+            -- hits the cache
+            log_property("wasmx.const_property") -- returns 1
+            log_property("wasmx.dyn_property") -- returns 2
+            log_property("wasmx.const_property") -- returns 1
+            log_property("wasmx.dyn_property") -- returns 3
+
+            log_property("wasmx.nil_const_property") -- returns nil
+            log_property("wasmx.nil_dyn_property") -- returns nil
+            log_property("wasmx.nil_const_property") -- returns nil
+            log_property("wasmx.nil_dyn_property") -- returns nil
+
+            log_property("wasmx.empty_const_property") -- returns ""
+            log_property("wasmx.empty_dyn_property") -- returns ""
+            log_property("wasmx.empty_const_property") -- returns ""
+            log_property("wasmx.empty_dyn_property") -- returns ""
+        }
+    }
+--- response_body
+ok
+--- grep_error_log eval: qr/.*wasmx.*property.*/
+--- grep_error_log_out eval
+qr/^[^\n]*?\[info\] [^\n]*? getting wasmx.const_property, counter: 1[^\n]*?
+[^\n]*?\[info\] [^\n]*? wasmx.const_property: string "1"[^\n]*?
+[^\n]*?\[info\] [^\n]*? getting wasmx.dyn_property, counter: 2[^\n]*?
+[^\n]*?\[info\] [^\n]*? wasmx.dyn_property: string "2"[^\n]*?
+[^\n]*?\[info\] [^\n]*? wasmx.const_property: string "1"[^\n]*?
+[^\n]*?\[info\] [^\n]*? getting wasmx.dyn_property, counter: 3[^\n]*?
+[^\n]*?\[info\] [^\n]*? wasmx.dyn_property: string "3"[^\n]*?
+[^\n]*?\[info\] [^\n]*? getting wasmx.nil_const_property, counter: 4[^\n]*?
+[^\n]*?\[info\] [^\n]*? wasmx.nil_const_property: nil "nil"[^\n]*?
+[^\n]*?\[info\] [^\n]*? getting wasmx.nil_dyn_property, counter: 5[^\n]*?
+[^\n]*?\[info\] [^\n]*? wasmx.nil_dyn_property: nil "nil"[^\n]*?
+[^\n]*?\[info\] [^\n]*? wasmx.nil_const_property: nil "nil"[^\n]*?
+[^\n]*?\[info\] [^\n]*? getting wasmx.nil_dyn_property, counter: 6[^\n]*?
+[^\n]*?\[info\] [^\n]*? wasmx.nil_dyn_property: nil "nil"[^\n]*?
+[^\n]*?\[info\] [^\n]*? getting wasmx.empty_const_property, counter: 7[^\n]*?
+[^\n]*?\[info\] [^\n]*? wasmx.empty_const_property: string ""[^\n]*?
+[^\n]*?\[info\] [^\n]*? getting wasmx.empty_dyn_property, counter: 8[^\n]*?
+[^\n]*?\[info\] [^\n]*? wasmx.empty_dyn_property: string ""[^\n]*?
+[^\n]*?\[info\] [^\n]*? wasmx.empty_const_property: string ""[^\n]*?
+[^\n]*?\[info\] [^\n]*? getting wasmx.empty_dyn_property, counter: 9[^\n]*?
+[^\n]*?\[info\] [^\n]*? wasmx.empty_dyn_property: string ""[^\n]*?$/
+--- no_error_log
+[error]
+[crit]
+
+
+
+=== TEST 11: set_property_getter() - errors in getter are caught by pcall in Lua library and don't crash the worker
+--- wasm_modules: hostcalls
+--- http_config
+    init_worker_by_lua_block {
+        local proxy_wasm = require "resty.wasmx.proxy_wasm"
+        local filters = {
+            { name = "hostcalls" },
+        }
+
+        _G.c_plan = assert(proxy_wasm.new(filters))
+        assert(proxy_wasm.load(_G.c_plan))
+    }
+--- config
+    location /t {
+        proxy_wasm hostcalls 'on=response_body \
+                              test=/t/log/property \
+                              name=wasmx.my_property';
+
+        rewrite_by_lua_block {
+            local proxy_wasm = require "resty.wasmx.proxy_wasm"
+            assert(proxy_wasm.attach(_G.c_plan))
+
+            local function getter(key)
+                error("crash!")
+            end
+
+            assert(proxy_wasm.set_property_getter(getter))
+
+            assert(proxy_wasm.start())
+            ngx.say("ok")
+        }
+    }
+--- response_body
+ok
+--- error_log eval
+[
+    qr/\[info\] .*? \[hostcalls\] on_response_body/,
+    qr/\[error\] .*? Lua error in property handler: rewrite_by_lua\(nginx.conf:[0-9]+\):[0-9]+: crash\!/,
+]
+--- no_error_log
+[emerg]
diff --git a/t/04-openresty/ffi/305-proxy_wasm_set_property_setter.t b/t/04-openresty/ffi/305-proxy_wasm_set_property_setter.t
new file mode 100644
index 000000000..04f05af05
--- /dev/null
+++ b/t/04-openresty/ffi/305-proxy_wasm_set_property_setter.t
@@ -0,0 +1,616 @@
+# vim:set ft= ts=4 sw=4 et fdm=marker:
+
+use strict;
+use lib '.';
+use t::TestWasm::Lua;
+
+skip_no_openresty();
+
+plan tests => repeat_each() * (blocks() * 5);
+
+run_tests();
+
+__DATA__
+
+=== TEST 1: set_property_setter() - setting host properties setter fails on init_worker_by_lua
+--- wasm_modules: on_phases
+--- http_config
+    init_worker_by_lua_block {
+        local proxy_wasm = require "resty.wasmx.proxy_wasm"
+        local filters = {
+            { name = "on_phases" },
+        }
+
+        _G.c_plan = assert(proxy_wasm.new(filters))
+        assert(proxy_wasm.load(_G.c_plan))
+
+        local tbl = {}
+
+        local function setter(key, value)
+            tbl[key] = value
+            return true
+        end
+
+        assert(proxy_wasm.set_property_setter(setter))
+    }
+--- config
+    location /t {
+        rewrite_by_lua_block {
+            ngx.say("ok")
+        }
+    }
+--- response_body
+ok
+--- error_log eval
+[
+    qr/\[error\] .*? cannot set host properties setter outside of a request/,
+    qr/\[error\] .*? init_worker_by_lua(\(nginx\.conf:\d+\))?:\d+: could not set property setter/,
+]
+--- no_error_log
+[crit]
+
+
+
+=== TEST 2: set_property_setter() - setting host properties setter works on rewrite_by_lua
+--- wasm_modules: hostcalls
+--- http_config
+    init_worker_by_lua_block {
+        local proxy_wasm = require "resty.wasmx.proxy_wasm"
+        local filters = {
+            { name = "hostcalls" },
+        }
+
+        _G.c_plan = assert(proxy_wasm.new(filters))
+        assert(proxy_wasm.load(_G.c_plan))
+    }
+--- config
+    location /t {
+        proxy_wasm hostcalls 'on=response_body \
+                              test=/t/log/property \
+                              name=wasmx.my_property';
+
+        rewrite_by_lua_block {
+            local proxy_wasm = require "resty.wasmx.proxy_wasm"
+            assert(proxy_wasm.attach(_G.c_plan))
+
+            local tbl = {}
+
+            local function setter(key, value)
+                local new_value = value:upper()
+                tbl[key] = new_value
+                return true, new_value
+            end
+
+            assert(proxy_wasm.set_property_setter(setter))
+
+            assert(proxy_wasm.set_property("wasmx.my_property", "my_value"))
+
+            assert(proxy_wasm.start())
+            ngx.say("ok")
+        }
+    }
+--- response_body
+ok
+--- error_log eval
+[
+    qr/\[info\] .*? \[hostcalls\] on_response_body/,
+    qr/\[info\] .*? wasmx.my_property: MY_VALUE/,
+]
+--- no_error_log
+[error]
+
+
+
+=== TEST 3: set_property_setter() - setting host properties setter works on access_by_lua
+--- wasm_modules: hostcalls
+--- http_config
+    init_worker_by_lua_block {
+        local proxy_wasm = require "resty.wasmx.proxy_wasm"
+        local filters = {
+            { name = "hostcalls" },
+        }
+
+        _G.c_plan = assert(proxy_wasm.new(filters))
+        assert(proxy_wasm.load(_G.c_plan))
+    }
+--- config
+    location /t {
+        proxy_wasm hostcalls 'on=response_body \
+                              test=/t/log/property \
+                              name=wasmx.my_property';
+
+        access_by_lua_block {
+            local proxy_wasm = require "resty.wasmx.proxy_wasm"
+            assert(proxy_wasm.attach(_G.c_plan))
+
+            local tbl = {}
+
+            local function setter(key, value)
+                local new_value = value:upper()
+                tbl[key] = new_value
+                return true, new_value
+            end
+
+            assert(proxy_wasm.set_property_setter(setter))
+
+            assert(proxy_wasm.set_property("wasmx.my_property", "my_value"))
+
+            assert(proxy_wasm.start())
+            ngx.say("ok")
+        }
+    }
+--- response_body
+ok
+--- error_log eval
+[
+    qr/\[info\] .*? \[hostcalls\] on_response_body/,
+    qr/\[info\] .*? wasmx.my_property: MY_VALUE/,
+]
+--- no_error_log
+[error]
+
+
+
+=== TEST 4: set_property_setter() - setting host properties setter works on header_filter_by_lua
+--- wasm_modules: hostcalls
+--- http_config
+    init_worker_by_lua_block {
+        local proxy_wasm = require "resty.wasmx.proxy_wasm"
+        local filters = {
+            { name = "hostcalls" },
+        }
+
+        _G.c_plan = assert(proxy_wasm.new(filters))
+        assert(proxy_wasm.load(_G.c_plan))
+    }
+--- config
+    location /t {
+        proxy_wasm hostcalls 'on=response_body \
+                              test=/t/log/property \
+                              name=wasmx.my_property';
+
+        rewrite_by_lua_block {
+            local proxy_wasm = require "resty.wasmx.proxy_wasm"
+            assert(proxy_wasm.attach(_G.c_plan))
+
+            assert(proxy_wasm.start())
+            ngx.say("ok")
+        }
+
+        header_filter_by_lua_block {
+            local proxy_wasm = require "resty.wasmx.proxy_wasm"
+
+            local tbl = {}
+
+            local function setter(key, value)
+                local new_value = value:upper()
+                tbl[key] = new_value
+                return true, new_value
+            end
+
+            assert(proxy_wasm.set_property_setter(setter))
+
+            assert(proxy_wasm.set_property("wasmx.my_property", "my_value"))
+        }
+    }
+--- response_body
+ok
+--- error_log eval
+[
+    qr/\[info\] .*? \[hostcalls\] on_response_body/,
+    qr/\[info\] .*? wasmx.my_property: MY_VALUE/,
+]
+--- no_error_log
+[error]
+
+
+
+=== TEST 5: set_property_setter() - setting host properties setter works on body_filter_by_lua
+--- wasm_modules: hostcalls
+--- http_config
+    init_worker_by_lua_block {
+        local proxy_wasm = require "resty.wasmx.proxy_wasm"
+        local filters = {
+            { name = "hostcalls" },
+        }
+
+        _G.c_plan = assert(proxy_wasm.new(filters))
+        assert(proxy_wasm.load(_G.c_plan))
+    }
+--- config
+    location /t {
+        proxy_wasm hostcalls 'on=response_body \
+                              test=/t/log/property \
+                              name=wasmx.my_property';
+
+        rewrite_by_lua_block {
+            local proxy_wasm = require "resty.wasmx.proxy_wasm"
+            assert(proxy_wasm.attach(_G.c_plan))
+
+            assert(proxy_wasm.start())
+            ngx.say("ok")
+        }
+
+        body_filter_by_lua_block {
+            local proxy_wasm = require "resty.wasmx.proxy_wasm"
+
+            local tbl = {}
+
+            local function setter(key, value)
+                local new_value = value:upper()
+                tbl[key] = new_value
+                return true, new_value
+            end
+
+            assert(proxy_wasm.set_property_setter(setter))
+
+            assert(proxy_wasm.set_property("wasmx.my_property", "my_value"))
+        }
+    }
+--- response_body
+ok
+--- error_log eval
+[
+    qr/\[info\] .*? \[hostcalls\] on_response_body/,
+    qr/\[info\] .*? wasmx.my_property: MY_VALUE/,
+]
+--- no_error_log
+[error]
+
+
+
+=== TEST 6: set_property_setter() - setting host properties setter works on log_by_lua
+--- wasm_modules: hostcalls
+--- http_config
+    init_worker_by_lua_block {
+        local proxy_wasm = require "resty.wasmx.proxy_wasm"
+        local filters = {
+            { name = "hostcalls" },
+        }
+
+        _G.c_plan = assert(proxy_wasm.new(filters))
+        assert(proxy_wasm.load(_G.c_plan))
+    }
+--- config
+    location /t {
+        proxy_wasm_request_headers_in_access on;
+
+        proxy_wasm hostcalls 'on=log \
+                              test=/t/log/property \
+                              name=wasmx.my_property';
+
+        access_by_lua_block {
+            local proxy_wasm = require "resty.wasmx.proxy_wasm"
+            assert(proxy_wasm.attach(_G.c_plan))
+
+            assert(proxy_wasm.start())
+            ngx.say("ok")
+        }
+
+        log_by_lua_block {
+            local proxy_wasm = require "resty.wasmx.proxy_wasm"
+
+            local tbl = {}
+
+            local function setter(key, value)
+                local new_value = value:upper()
+                tbl[key] = new_value
+                return true, new_value
+            end
+
+            assert(proxy_wasm.set_property_setter(setter))
+
+            assert(proxy_wasm.set_property("wasmx.my_property", "my_value"))
+        }
+    }
+--- response_body
+ok
+--- error_log eval
+[
+    qr/\[info\] .*? \[hostcalls\] on_log/,
+    qr/\[info\] .*? wasmx.my_property: MY_VALUE/,
+]
+--- no_error_log
+[error]
+
+
+
+=== TEST 7: set_property_setter() - setting property setter at startup doesn't reset filter list
+--- wasm_modules: hostcalls
+--- http_config
+    init_worker_by_lua_block {
+        local proxy_wasm = require "resty.wasmx.proxy_wasm"
+        local filters = {
+            { name = "hostcalls", config = "on=log " ..
+                                           "test=/t/log/property " ..
+                                           "name=wasmx.my_property" },
+        }
+
+        _G.c_plan = assert(proxy_wasm.new(filters))
+
+        assert(proxy_wasm.load(_G.c_plan))
+    }
+--- config
+    location /t {
+        proxy_wasm_request_headers_in_access on;
+
+        access_by_lua_block {
+            local proxy_wasm = require "resty.wasmx.proxy_wasm"
+
+            assert(proxy_wasm.attach(_G.c_plan))
+
+            local function setter(key, value)
+                if key == "wasmx.my_property" then
+                    return true, "foo"
+                end
+                return false
+            end
+
+            assert(proxy_wasm.set_property_setter(setter))
+
+            assert(proxy_wasm.start())
+
+            ngx.say("ok")
+        }
+
+        body_filter_by_lua_block {
+            local proxy_wasm = require "resty.wasmx.proxy_wasm"
+
+            assert(proxy_wasm.set_property("wasmx.my_property", "bar"))
+        }
+    }
+--- response_body
+ok
+--- error_log eval
+[
+    qr/\[info\] .*? \[hostcalls\] on_log/,
+    qr/\[info\] .*?hostcalls.*? wasmx.my_property: foo/,
+]
+--- no_error_log
+[error]
+
+
+
+=== TEST 8: set_property_setter() - setter returning falsy logs custom message or "unknown error"
+--- wasm_modules: hostcalls
+--- http_config
+    init_worker_by_lua_block {
+        local proxy_wasm = require "resty.wasmx.proxy_wasm"
+        local filters = {
+            { name = "hostcalls" },
+        }
+
+        _G.c_plan = assert(proxy_wasm.new(filters))
+        assert(proxy_wasm.load(_G.c_plan))
+    }
+--- config
+    proxy_wasm hostcalls 'on=log \
+                          test=/t/log/property \
+                          name=wasmx.fail1_property';
+
+    location /t {
+        access_by_lua_block {
+            local proxy_wasm = require "resty.wasmx.proxy_wasm"
+            assert(proxy_wasm.attach(_G.c_plan))
+
+            local function setter(key)
+                if key == "wasmx.fail1_property" then
+                    return nil, "first wasmx property custom error"
+
+                elseif key == "wasmx.fail2_property" then
+                    return false, "second wasmx property custom error"
+
+                elseif key == "wasmx.fail3_property" then
+                    return nil
+
+                elseif key == "wasmx.fail4_property" then
+                    return false
+                end
+            end
+
+            assert(proxy_wasm.set_property_setter(setter))
+
+            local msg = "result:"
+            for i = 1, 4 do
+                local key = "wasmx.fail" .. i .. "_property"
+                local ok, err = proxy_wasm.set_property(key, "wat")
+                if not ok then
+                    msg = msg .. "\n" .. err
+                end
+            end
+
+            assert(proxy_wasm.start())
+            ngx.say(msg)
+        }
+    }
+--- response_body
+result:
+unknown error
+unknown error
+unknown error
+unknown error
+--- grep_error_log eval: qr/.*property.*/
+--- grep_error_log_out eval
+qr/^[^\n]*?\[error\] [^\n]*? error in property handler: first wasmx property custom error[^\n]*?
+[^\n]*?\[error\] [^\n]*? error in property handler: second wasmx property custom error[^\n]*?
+[^\n]*?\[error\] [^\n]*? error in property handler: unknown error[^\n]*?
+[^\n]*?\[error\] [^\n]*? error in property handler: unknown error[^\n]*?
+[^\n]*?\[info\] [^\n]*? property not found: wasmx.fail1_property[^\n]*?$/
+--- no_error_log
+[crit]
+[alert]
+
+
+
+=== TEST 9: set_property_setter() - setter returning true on 3rd value caches result
+--- wasm_modules: hostcalls
+--- http_config
+    init_worker_by_lua_block {
+        local proxy_wasm = require "resty.wasmx.proxy_wasm"
+        local filters = {
+            { name = "hostcalls" },
+        }
+
+        _G.c_plan = assert(proxy_wasm.new(filters))
+        assert(proxy_wasm.load(_G.c_plan))
+    }
+--- config
+    location /t {
+        access_by_lua_block {
+            local proxy_wasm = require "resty.wasmx.proxy_wasm"
+            assert(proxy_wasm.attach(_G.c_plan))
+
+            local counter = 0
+
+            local tbl = {}
+
+            local function setter(key, value)
+                counter = counter + 1
+
+                if value and #value > 0 then
+                    value = value:upper() .. " " .. tostring(counter)
+                end
+
+                tbl[key] = value
+
+                ngx.log(ngx.INFO, "setting ", key, " to ", value, ", counter: " .. counter)
+
+                return true, value, (key:match("const") and true or false)
+            end
+
+            assert(proxy_wasm.set_property_setter(setter))
+
+            local function getter(key)
+                counter = counter + 1
+
+                ngx.log(ngx.INFO, "getting ", key, " via getter, counter: ", counter)
+
+                local value = tbl[key]
+
+                if value and #value > 0 then
+                    value = value .. " " .. tostring(counter)
+                end
+
+                return true, value
+            end
+
+            assert(proxy_wasm.set_property_getter(getter))
+
+            assert(proxy_wasm.start())
+            ngx.say("ok")
+        }
+
+        log_by_lua_block {
+            local proxy_wasm = require "resty.wasmx.proxy_wasm"
+
+            local function log_property(k)
+                local v = proxy_wasm.get_property(k)
+                ngx.log(ngx.INFO, k, ": ", type(v), " \"", v, "\"")
+            end
+
+            -- two set_property operations, each will hit the setter.
+            -- four get_property operations,
+            -- but only wasmx.dyn_property will hit the getter
+            -- because the setter to wasmx.const_property cached the result.
+            proxy_wasm.set_property("wasmx.const_property", "hello") -- sets "HELLO 1"
+            log_property("wasmx.const_property") -- returns "HELLO 1"
+            proxy_wasm.set_property("wasmx.dyn_property", "hi") -- sets "HI 2"
+            log_property("wasmx.dyn_property") -- returns "HI 2 3"
+            log_property("wasmx.const_property") -- returns "HELLO 1"
+            log_property("wasmx.dyn_property") -- returns "HI 2 4"
+
+            proxy_wasm.set_property("wasmx.nil_const_property", nil) -- sets nil
+            log_property("wasmx.nil_const_property") -- returns nil
+            proxy_wasm.set_property("wasmx.nil_dyn_property", nil) -- sets nil
+            log_property("wasmx.nil_dyn_property") -- returns nil
+            log_property("wasmx.nil_const_property") -- returns nil
+            log_property("wasmx.nil_dyn_property") -- returns nil
+
+            proxy_wasm.set_property("wasmx.empty_const_property", "") -- sets ""
+            log_property("wasmx.empty_const_property") -- returns ""
+            proxy_wasm.set_property("wasmx.empty_dyn_property", "") -- sets ""
+            log_property("wasmx.empty_dyn_property") -- returns ""
+            log_property("wasmx.empty_const_property") -- returns ""
+            log_property("wasmx.empty_dyn_property") -- returns ""
+        }
+    }
+--- response_body
+ok
+--- grep_error_log eval: qr/.*wasmx.*property.*/
+--- grep_error_log_out eval
+qr/^[^\n]*?\[info\] [^\n]*? setting wasmx.const_property to HELLO 1, counter: 1[^\n]*?
+[^\n]*?\[info\] [^\n]*? wasmx.const_property: string "HELLO 1"[^\n]*?
+[^\n]*?\[info\] [^\n]*? setting wasmx.dyn_property to HI 2, counter: 2[^\n]*?
+[^\n]*?\[info\] [^\n]*? getting wasmx.dyn_property via getter, counter: 3[^\n]*?
+[^\n]*?\[info\] [^\n]*? wasmx.dyn_property: string "HI 2 3"[^\n]*?
+[^\n]*?\[info\] [^\n]*? wasmx.const_property: string "HELLO 1"[^\n]*?
+[^\n]*?\[info\] [^\n]*? getting wasmx.dyn_property via getter, counter: 4[^\n]*?
+[^\n]*?\[info\] [^\n]*? wasmx.dyn_property: string "HI 2 4"[^\n]*?
+[^\n]*?\[info\] [^\n]*? setting wasmx.nil_const_property to nil, counter: 5[^\n]*?
+[^\n]*?\[info\] [^\n]*? wasmx.nil_const_property: nil "nil"[^\n]*?
+[^\n]*?\[info\] [^\n]*? setting wasmx.nil_dyn_property to nil, counter: 6[^\n]*?
+[^\n]*?\[info\] [^\n]*? getting wasmx.nil_dyn_property via getter, counter: 7[^\n]*?
+[^\n]*?\[info\] [^\n]*? wasmx.nil_dyn_property: nil "nil"[^\n]*?
+[^\n]*?\[info\] [^\n]*? wasmx.nil_const_property: nil "nil"[^\n]*?
+[^\n]*?\[info\] [^\n]*? getting wasmx.nil_dyn_property via getter, counter: 8[^\n]*?
+[^\n]*?\[info\] [^\n]*? wasmx.nil_dyn_property: nil "nil"[^\n]*?
+[^\n]*?\[info\] [^\n]*? setting wasmx.empty_const_property to , counter: 9[^\n]*?
+[^\n]*?\[info\] [^\n]*? wasmx.empty_const_property: string ""[^\n]*?
+[^\n]*?\[info\] [^\n]*? setting wasmx.empty_dyn_property to , counter: 10[^\n]*?
+[^\n]*?\[info\] [^\n]*? getting wasmx.empty_dyn_property via getter, counter: 11[^\n]*?
+[^\n]*?\[info\] [^\n]*? wasmx.empty_dyn_property: string ""[^\n]*?
+[^\n]*?\[info\] [^\n]*? wasmx.empty_const_property: string ""[^\n]*?
+[^\n]*?\[info\] [^\n]*? getting wasmx.empty_dyn_property via getter, counter: 12[^\n]*?
+[^\n]*?\[info\] [^\n]*? wasmx.empty_dyn_property: string ""[^\n]*?$/
+--- no_error_log
+[error]
+[crit]
+
+
+
+=== TEST 10: set_property_setter() - errors in setter are caught by pcall in Lua library and don't crash the worker
+--- wasm_modules: hostcalls
+--- http_config
+    init_worker_by_lua_block {
+        local proxy_wasm = require "resty.wasmx.proxy_wasm"
+        local filters = {
+            { name = "hostcalls" },
+        }
+
+        _G.c_plan = assert(proxy_wasm.new(filters))
+        assert(proxy_wasm.load(_G.c_plan))
+    }
+--- config
+    location /t {
+        proxy_wasm hostcalls 'on=response_body \
+                              test=/t/log/property \
+                              name=wasmx.my_property';
+
+        rewrite_by_lua_block {
+            local proxy_wasm = require "resty.wasmx.proxy_wasm"
+            assert(proxy_wasm.attach(_G.c_plan))
+
+            local tbl = {}
+
+            local function setter(key, value)
+                error("crash!")
+            end
+
+            assert(proxy_wasm.set_property_setter(setter))
+
+            local ok, err = proxy_wasm.set_property("wasmx.my_property", "my_value")
+            assert((not ok) and err == "unknown error")
+
+            assert(proxy_wasm.start())
+            ngx.say("ok")
+        }
+    }
+--- response_body
+ok
+--- error_log eval
+[
+    qr/\[info\] .*? \[hostcalls\] on_response_body/,
+    qr/\[error\] .*? Lua error in property handler: rewrite_by_lua\(nginx.conf:[0-9]+\):[0-9]+: crash\!/,
+]
+--- no_error_log
+[emerg]