afb-proto-ws: Split afb-stub-ws in twoeel_4.99.1eel/4.99.14.99.1

The file afb-stub-ws is split in two parts:
 - afb-stub-ws: implements the interface between
   xreq and protocol.
 - afb-proto-ws: implements the pbinary protocol
   over wer sockets

The intent is to have a clean separation between
a kind of generic stub and the protocol implmentation.

This will allow soon to provide a library to access
directly in C to the websocket of an API exposed
through the otpion --ws-server.

At the moment, the protocol implementation is on
websockets but in the futur it will be cleanly
rewritten to use any binary transport.

This commit also fixe a double free in subcalls.

Change-Id: I831787533db9fe073d060dd8ee9401cbab2894e1
Signed-off-by: José Bollo <jose.bollo@iot.bzh>

5 files changed, 1473 insertions, 876 deletions

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 14c5120d..74702ad3 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -52,6 +52,7 @@ ADD_LIBRARY(afb-lib STATIC
 	afb-method.c
 	afb-monitor.c
 	afb-msg-json.c
+	afb-proto-ws.c
 	afb-session.c
 	afb-stub-ws.c
 	afb-svc.c
diff --git a/src/afb-proto-ws.c b/src/afb-proto-ws.c
new file mode 100644
index 00000000..1f17cd77
--- /dev/null
+++ b/src/afb-proto-ws.c
@@ -0,0 +1,1171 @@
+/*
+ * Copyright (C) 2015, 2016, 2017 "IoT.bzh"
+ * Author José Bollo <jose.bollo@iot.bzh>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define _GNU_SOURCE
+
+#define NO_PLUGIN_VERBOSE_MACRO
+
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+#include <endian.h>
+#include <netdb.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <pthread.h>
+
+#include <json-c/json.h>
+#include <systemd/sd-event.h>
+
+#include "afb-common.h"
+
+#include "afb-ws.h"
+#include "afb-msg-json.h"
+#include "afb-proto-ws.h"
+#include "verbose.h"
+
+struct afb_proto_ws;
+
+/******** implementation of internal binder protocol per api **************/
+/*
+
+This protocol is asymetric: there is a client and a server
+
+The client can require the following actions:
+
+  - call a verb
+
+  - ask for description
+
+The server must reply to the previous actions by 
+
+  - answering success or failure of the call
+
+  - answering the required description
+
+The server can also within the context of a call
+
+  - make a subcall
+
+  - subscribe or unsubscribe an event
+
+For the purpose of handling events the server can:
+
+  - create/destroy an event
+
+  - push or brodcast data as an event
+
+*/
+/************** constants for protocol definition *************************/
+
+#define CHAR_FOR_CALL             'C'
+#define CHAR_FOR_ANSWER_SUCCESS   'T'
+#define CHAR_FOR_ANSWER_FAIL      'F'
+#define CHAR_FOR_EVT_BROADCAST    '*'
+#define CHAR_FOR_EVT_ADD          '+'
+#define CHAR_FOR_EVT_DEL          '-'
+#define CHAR_FOR_EVT_PUSH         '!'
+#define CHAR_FOR_EVT_SUBSCRIBE    'S'
+#define CHAR_FOR_EVT_UNSUBSCRIBE  'U'
+#define CHAR_FOR_SUBCALL_CALL     'B'
+#define CHAR_FOR_SUBCALL_REPLY    'R'
+#define CHAR_FOR_DESCRIBE         'D'
+#define CHAR_FOR_DESCRIPTION      'd'
+
+/******************* handling subcalls *****************************/
+
+/**
+ * Structure on server side for recording pending
+ * subcalls.
+ */
+struct server_subcall
+{
+	struct server_subcall *next;	/**< next subcall for the client */
+	uint32_t subcallid;		/**< the subcallid */
+	void (*callback)(void*, int, struct json_object*); /**< callback on completion */
+	void *closure;			/**< closure of the callback */
+};
+
+/**
+ * Structure for sending back replies on client side
+ */
+struct afb_proto_ws_subcall
+{
+	struct afb_proto_ws *protows;	/**< proto descriptor */
+	void *buffer;
+	uint32_t subcallid;		/**< subcallid for the reply */
+};
+
+/*
+ * structure for recording calls on client side
+ */
+struct client_call {
+	struct client_call *next;	/* the next call */
+	struct afb_proto_ws *protows;	/* the proto_ws */
+	void *request;
+	uint32_t callid;		/* the message identifier */
+};
+
+/*
+ * structure for a ws request
+ */
+struct afb_proto_ws_call {
+	struct client_call *next;	/* the next call */
+	struct afb_proto_ws *protows;	/* the client of the request */
+	uint32_t refcount;		/* reference count */
+	uint32_t callid;		/* the incoming request callid */
+	char *buffer;			/* the incoming buffer */
+};
+
+/*
+ * structure for recording describe requests
+ */
+struct client_describe
+{
+	struct client_describe *next;
+	struct afb_proto_ws *protows;
+	void (*callback)(void*, struct json_object*);
+	void *closure;
+	uint32_t descid;
+};
+
+/*
+ * structure for jobs of describing
+ */
+struct afb_proto_ws_describe
+{
+	struct afb_proto_ws *protows;
+	uint32_t descid;
+};
+
+/******************* proto description for client or servers ******************/
+
+struct afb_proto_ws
+{
+	/* count of references */
+	int refcount;
+
+	/* file descriptor */
+	int fd;
+
+	/* resource control */
+	pthread_mutex_t mutex;
+
+	/* websocket */
+	struct afb_ws *ws;
+
+	/* the client closure */
+	void *closure;
+
+	/* the client side interface */
+	const struct afb_proto_ws_client_itf *client_itf;
+
+	/* the server side interface */
+	const struct afb_proto_ws_server_itf *server_itf;
+
+	/* emitted calls (client side) */
+	struct client_call *calls;
+
+	/* pending subcalls (server side) */
+	struct server_subcall *subcalls;
+
+	/* pending description (client side) */
+	struct client_describe *describes;
+
+	/* on hangup callback */
+	void (*on_hangup)(void *closure);
+};
+
+/******************* common useful tools **********************************/
+
+/**
+ * translate a pointer to some integer
+ * @param ptr the pointer to translate
+ * @return an integer
+ */
+static inline uint32_t ptr2id(void *ptr)
+{
+	return (uint32_t)(((intptr_t)ptr) >> 6);
+}
+
+/******************* serialisation part **********************************/
+
+struct readbuf
+{
+	char *base, *head, *end;
+};
+
+#define WRITEBUF_COUNT_MAX  32
+struct writebuf
+{
+	struct iovec iovec[WRITEBUF_COUNT_MAX];
+	uint32_t uints[WRITEBUF_COUNT_MAX];
+	int count;
+};
+
+static char *readbuf_get(struct readbuf *rb, uint32_t length)
+{
+	char *before = rb->head;
+	char *after = before + length;
+	if (after > rb->end)
+		return 0;
+	rb->head = after;
+	return before;
+}
+
+static int readbuf_char(struct readbuf *rb, char *value)
+{
+	if (rb->head >= rb->end)
+		return 0;
+	*value = *rb->head++;
+	return 1;
+}
+
+static int readbuf_uint32(struct readbuf *rb, uint32_t *value)
+{
+	char *after = rb->head + sizeof *value;
+	if (after > rb->end)
+		return 0;
+	memcpy(value, rb->head, sizeof *value);
+	rb->head = after;
+	*value = le32toh(*value);
+	return 1;
+}
+
+static int readbuf_string(struct readbuf *rb, const char **value, size_t *length)
+{
+	uint32_t len;
+	if (!readbuf_uint32(rb, &len) || !len)
+		return 0;
+	if (length)
+		*length = (size_t)(len - 1);
+	return (*value = readbuf_get(rb, len)) != NULL &&  rb->head[-1] == 0;
+}
+
+static int readbuf_object(struct readbuf *rb, struct json_object **object)
+{
+	const char *string;
+	struct json_object *o;
+	int rc = readbuf_string(rb, &string, NULL);
+	if (rc) {
+		o = json_tokener_parse(string);
+		if (o == NULL && strcmp(string, "null"))
+			o = json_object_new_string(string);
+		*object = o;
+	}
+	return rc;
+}
+
+static int writebuf_put(struct writebuf *wb, const void *value, size_t length)
+{
+	int i = wb->count;
+	if (i == WRITEBUF_COUNT_MAX)
+		return 0;
+	wb->iovec[i].iov_base = (void*)value;
+	wb->iovec[i].iov_len = length;
+	wb->count = i + 1;
+	return 1;
+}
+
+static int writebuf_char(struct writebuf *wb, char value)
+{
+	int i = wb->count;
+	if (i == WRITEBUF_COUNT_MAX)
+		return 0;
+	*(char*)&wb->uints[i] = value;
+	wb->iovec[i].iov_base = &wb->uints[i];
+	wb->iovec[i].iov_len = 1;
+	wb->count = i + 1;
+	return 1;
+}
+
+static int writebuf_uint32(struct writebuf *wb, uint32_t value)
+{
+	int i = wb->count;
+	if (i == WRITEBUF_COUNT_MAX)
+		return 0;
+	wb->uints[i] = htole32(value);
+	wb->iovec[i].iov_base = &wb->uints[i];
+	wb->iovec[i].iov_len = sizeof wb->uints[i];
+	wb->count = i + 1;
+	return 1;
+}
+
+static int writebuf_string_length(struct writebuf *wb, const char *value, size_t length)
+{
+	uint32_t len = (uint32_t)++length;
+	return (size_t)len == length && len && writebuf_uint32(wb, len) && writebuf_put(wb, value, length);
+}
+
+static int writebuf_string(struct writebuf *wb, const char *value)
+{
+	return writebuf_string_length(wb, value, strlen(value));
+}
+
+static int writebuf_object(struct writebuf *wb, struct json_object *object)
+{
+	const char *string = json_object_to_json_string_ext(object, JSON_C_TO_STRING_PLAIN);
+	return string != NULL && writebuf_string(wb, string);
+}
+
+/******************* ws request part for server *****************/
+
+void afb_proto_ws_call_addref(struct afb_proto_ws_call *call)
+{
+	__atomic_add_fetch(&call->refcount, 1, __ATOMIC_RELAXED);
+}
+
+void afb_proto_ws_call_unref(struct afb_proto_ws_call *call)
+{
+	if (__atomic_sub_fetch(&call->refcount, 1, __ATOMIC_RELAXED))
+		return;
+
+	afb_proto_ws_unref(call->protows);
+	free(call->buffer);
+	free(call);
+}
+
+int afb_proto_ws_call_success(struct afb_proto_ws_call *call, struct json_object *obj, const char *info)
+{
+	int rc = -1;
+	struct writebuf wb = { .count = 0 };
+
+	if (writebuf_char(&wb, CHAR_FOR_ANSWER_SUCCESS)
+	 && writebuf_uint32(&wb, call->callid)
+	 && writebuf_string(&wb, info ?: "")
+	 && writebuf_object(&wb, obj)) {
+		rc = afb_ws_binary_v(call->protows->ws, wb.iovec, wb.count);
+		if (rc >= 0) {
+			rc = 0;
+			goto success;
+		}
+	}
+	ERROR("error while sending success");
+success:
+	return rc;
+}
+
+int afb_proto_ws_call_fail(struct afb_proto_ws_call *call, const char *status, const char *info)
+{
+	int rc = -1;
+	struct writebuf wb = { .count = 0 };
+
+	if (writebuf_char(&wb, CHAR_FOR_ANSWER_FAIL)
+	 && writebuf_uint32(&wb, call->callid)
+	 && writebuf_string(&wb, status)
+	 && writebuf_string(&wb, info ? : "")) {
+		rc = afb_ws_binary_v(call->protows->ws, wb.iovec, wb.count);
+		if (rc >= 0) {
+			rc = 0;
+			goto success;
+		}
+	}
+	ERROR("error while sending fail");
+success:
+	return rc;
+}
+
+int afb_proto_ws_call_subcall(struct afb_proto_ws_call *call, const char *api, const char *verb, struct json_object *args, void (*callback)(void*, int, struct json_object*), void *cb_closure)
+{
+	int rc = -1;
+	struct writebuf wb = { .count = 0 };
+	struct server_subcall *sc, *osc;
+	struct afb_proto_ws *protows = call->protows;
+
+	sc = malloc(sizeof *sc);
+	if (!sc)
+		errno = ENOMEM;
+	else {
+		sc->callback = callback;
+		sc->closure = cb_closure;
+
+		pthread_mutex_unlock(&protows->mutex);
+		sc->subcallid = ptr2id(sc);
+		do {
+			sc->subcallid++;
+			osc = protows->subcalls;
+			while(osc && osc->subcallid != sc->subcallid)
+				osc = osc->next;
+		} while (osc);
+		sc->next = protows->subcalls;
+		protows->subcalls = sc;
+		pthread_mutex_unlock(&protows->mutex);
+
+		if (writebuf_char(&wb, CHAR_FOR_SUBCALL_CALL)
+		 && writebuf_uint32(&wb, sc->subcallid)
+		 && writebuf_uint32(&wb, call->callid)
+		 && writebuf_string(&wb, api)
+		 && writebuf_string(&wb, verb)
+		 && writebuf_object(&wb, args)) {
+			rc = afb_ws_binary_v(protows->ws, wb.iovec, wb.count);
+			if (rc >= 0) {
+				rc = 0;
+				goto success;
+			}
+		}
+	}
+	ERROR("error while sending subcall");
+success:
+	return rc;
+}
+
+int afb_proto_ws_call_subscribe(struct afb_proto_ws_call *call, const char *event_name, int event_id)
+{
+	int rc = -1;
+	struct writebuf wb = { .count = 0 };
+
+	if (writebuf_char(&wb, CHAR_FOR_EVT_SUBSCRIBE)
+	 && writebuf_uint32(&wb, call->callid)
+	 && writebuf_uint32(&wb, (uint32_t)event_id)
+	 && writebuf_string(&wb, event_name)) {
+		rc = afb_ws_binary_v(call->protows->ws, wb.iovec, wb.count);
+		if (rc >= 0) {
+			rc = 0;
+			goto success;
+		}
+	}
+	ERROR("error while subscribing event");
+success:
+	return rc;
+}
+
+int afb_proto_ws_call_unsubscribe(struct afb_proto_ws_call *call, const char *event_name, int event_id)
+{
+	int rc = -1;
+	struct writebuf wb = { .count = 0 };
+
+	if (writebuf_char(&wb, CHAR_FOR_EVT_UNSUBSCRIBE)
+	 && writebuf_uint32(&wb, call->callid)
+	 && writebuf_uint32(&wb, (uint32_t)event_id)
+	 && writebuf_string(&wb, event_name)) {
+		rc = afb_ws_binary_v(call->protows->ws, wb.iovec, wb.count);
+		if (rc >= 0) {
+			rc = 0;
+			goto success;
+		}
+	}
+	ERROR("error while subscribing event");
+success:
+	return rc;
+}
+
+/******************* client part **********************************/
+
+/* search a memorized call */
+static struct client_call *client_call_search(struct afb_proto_ws *protows, uint32_t callid)
+{
+	struct client_call *call;
+
+	call = protows->calls;
+	while (call != NULL && call->callid != callid)
+		call = call->next;
+
+	return call;
+}
+
+/* free and release the memorizing call */
+static void client_call_destroy(struct client_call *call)
+{
+	struct client_call **prv;
+
+	prv = &call->protows->calls;
+	while (*prv != NULL) {
+		if (*prv == call) {
+			*prv = call->next;
+			break;
+		}
+		prv = &(*prv)->next;
+	}
+	free(call);
+}
+
+/* get event data from the message */
+static int client_msg_event_read(struct readbuf *rb, uint32_t *eventid, const char **name)
+{
+	return readbuf_uint32(rb, eventid) && readbuf_string(rb, name, NULL);
+}
+
+/* get event from the message */
+static int client_msg_call_get(struct afb_proto_ws *protows, struct readbuf *rb, struct client_call **call)
+{
+	uint32_t callid;
+
+	/* get event data from the message */
+	if (!readbuf_uint32(rb, &callid)) {
+		ERROR("Invalid message");
+		return 0;
+	}
+
+	/* get the call */
+	*call = client_call_search(protows, callid);
+	if (*call == NULL) {
+		ERROR("message not found");
+		return 0;
+	}
+
+	return 1;
+}
+
+/* adds an event */
+static void client_on_event_create(struct afb_proto_ws *protows, struct readbuf *rb)
+{
+	const char *event_name;
+	uint32_t event_id;
+
+	if (protows->client_itf->on_event_create && client_msg_event_read(rb, &event_id, &event_name))
+		protows->client_itf->on_event_create(protows->closure, event_name, (int)event_id);
+}
+
+/* removes an event */
+static void client_on_event_remove(struct afb_proto_ws *protows, struct readbuf *rb)
+{
+	const char *event_name;
+	uint32_t event_id;
+
+	if (protows->client_itf->on_event_remove && client_msg_event_read(rb, &event_id, &event_name))
+		protows->client_itf->on_event_remove(protows->closure, event_name, (int)event_id);
+}
+
+/* subscribes an event */
+static void client_on_event_subscribe(struct afb_proto_ws *protows, struct readbuf *rb)
+{
+	const char *event_name;
+	uint32_t event_id;
+	struct client_call *call;
+
+	if (protows->client_itf->on_event_subscribe && client_msg_call_get(protows, rb, &call) && client_msg_event_read(rb, &event_id, &event_name))
+		protows->client_itf->on_event_subscribe(protows->closure, call->request, event_name, (int)event_id);
+}
+
+/* unsubscribes an event */
+static void client_on_event_unsubscribe(struct afb_proto_ws *protows, struct readbuf *rb)
+{
+	const char *event_name;
+	uint32_t event_id;
+	struct client_call *call;
+
+	if (protows->client_itf->on_event_unsubscribe && client_msg_call_get(protows, rb, &call) && client_msg_event_read(rb, &event_id, &event_name))
+		protows->client_itf->on_event_unsubscribe(protows->closure, call->request, event_name, (int)event_id);
+}
+
+/* receives broadcasted events */
+static void client_on_event_broadcast(struct afb_proto_ws *protows, struct readbuf *rb)
+{
+	const char *event_name;
+	struct json_object *object;
+
+	if (protows->client_itf->on_event_broadcast && readbuf_string(rb, &event_name, NULL) && readbuf_object(rb, &object))
+		protows->client_itf->on_event_broadcast(protows->closure, event_name, object);
+}
+
+/* pushs an event */
+static void client_on_event_push(struct afb_proto_ws *protows, struct readbuf *rb)
+{
+	const char *event_name;
+	uint32_t event_id;
+	struct json_object *object;
+
+	if (protows->client_itf->on_event_push && client_msg_event_read(rb, &event_id, &event_name) && readbuf_object(rb, &object))
+		protows->client_itf->on_event_push(protows->closure, event_name, (int)event_id, object);
+}
+
+static void client_on_reply_success(struct afb_proto_ws *protows, struct readbuf *rb)
+{
+	struct client_call *call;
+	struct json_object *object;
+	const char *info;
+
+	if (!client_msg_call_get(protows, rb, &call))
+		return;
+
+	if (readbuf_string(rb, &info, NULL) && readbuf_object(rb, &object)) {
+		protows->client_itf->on_reply_success(protows->closure, call->request, object, info);
+	} else {
+		protows->client_itf->on_reply_fail(protows->closure, call->request, "proto-error", "can't process success");
+	}
+	client_call_destroy(call);
+}
+
+static void client_on_reply_fail(struct afb_proto_ws *protows, struct readbuf *rb)
+{
+	struct client_call *call;
+	const char *info, *status;
+
+	if (!client_msg_call_get(protows, rb, &call))
+		return;
+
+	if (readbuf_string(rb, &status, NULL) && readbuf_string(rb, &info, NULL)) {
+		protows->client_itf->on_reply_fail(protows->closure, call->request, status, info);
+	} else {
+		protows->client_itf->on_reply_fail(protows->closure, call->request, "proto-error", "can't process fail");
+	}
+	client_call_destroy(call);
+}
+
+/* send a subcall reply */
+static int client_send_subcall_reply(struct afb_proto_ws *protows, uint32_t subcallid, int status, json_object *object)
+{
+	struct writebuf wb = { .count = 0 };
+	char ie = status < 0;
+
+	return -!(writebuf_char(&wb, CHAR_FOR_SUBCALL_REPLY)
+	 && writebuf_uint32(&wb, subcallid)
+	 && writebuf_char(&wb, ie)
+	 && writebuf_object(&wb, object)
+	 && afb_ws_binary_v(protows->ws, wb.iovec, wb.count) >= 0);
+}
+
+/* callback for subcall reply */
+int afb_proto_ws_subcall_reply(struct afb_proto_ws_subcall *subcall, int status, struct json_object *result)
+{
+	int rc = client_send_subcall_reply(subcall->protows, subcall->subcallid, status, result);
+	afb_proto_ws_unref(subcall->protows);
+	free(subcall->buffer);
+	free(subcall);
+	return rc;
+}
+
+/* received a subcall request */
+static void client_on_subcall(struct afb_proto_ws *protows, struct readbuf *rb)
+{
+	struct afb_proto_ws_subcall *subcall;
+	struct client_call *call;
+	const char *api, *verb;
+	uint32_t subcallid;
+	struct json_object *object;
+
+	/* get the subcallid */
+	if (!readbuf_uint32(rb, &subcallid))
+		return;
+
+	/* if not expected drop it */
+	if (!protows->client_itf->on_subcall)
+		goto error;
+
+	/* retrieve the message data */
+	if (!client_msg_call_get(protows, rb, &call))
+		goto error;
+
+	/* allocation of the subcall */
+	subcall = malloc(sizeof *subcall);
+	if (!subcall)
+		goto error;
+
+	/* make the call */
+	if (readbuf_string(rb, &api, NULL)
+	 && readbuf_string(rb, &verb, NULL)
+	 && readbuf_object(rb, &object)) {
+		afb_proto_ws_addref(protows);
+		subcall->protows = protows;
+		subcall->subcallid = subcallid;
+		subcall->buffer = rb->base;
+		rb->base = NULL;
+		protows->client_itf->on_subcall(protows->closure, subcall, call->request, api, verb, object);
+		return;
+	}
+	free(subcall);
+error:
+	client_send_subcall_reply(protows, subcallid, 1, NULL);
+}
+
+static void client_on_description(struct afb_proto_ws *protows, struct readbuf *rb)
+{
+	uint32_t descid;
+	struct client_describe *desc, **prv;
+	struct json_object *object;
+
+	if (readbuf_uint32(rb, &descid)) {
+		prv = &protows->describes;
+		while ((desc = *prv) && desc->descid != descid)
+			prv = &desc->next;
+		if (desc) {
+			*prv = desc->next;
+			if (!readbuf_object(rb, &object))
+				object = NULL;
+			desc->callback(desc->closure, object);
+			free(desc);
+		}
+	}
+}
+
+/* callback when receiving binary data */
+static void client_on_binary(void *closure, char *data, size_t size)
+{
+	struct afb_proto_ws *protows;
+	struct readbuf rb;
+
+	rb.base = data;
+	if (size > 0) {
+		rb.head = data;
+		rb.end = data + size;
+		protows = closure;
+
+		pthread_mutex_lock(&protows->mutex);
+		switch (*rb.head++) {
+		case CHAR_FOR_ANSWER_SUCCESS: /* success */
+			client_on_reply_success(protows, &rb);
+			break;
+		case CHAR_FOR_ANSWER_FAIL: /* fail */
+			client_on_reply_fail(protows, &rb);
+			break;
+		case CHAR_FOR_EVT_BROADCAST: /* broadcast */
+			client_on_event_broadcast(protows, &rb);
+			break;
+		case CHAR_FOR_EVT_ADD: /* creates the event */
+			client_on_event_create(protows, &rb);
+			break;
+		case CHAR_FOR_EVT_DEL: /* removes the event */
+			client_on_event_remove(protows, &rb);
+			break;
+		case CHAR_FOR_EVT_PUSH: /* pushs the event */
+			client_on_event_push(protows, &rb);
+			break;
+		case CHAR_FOR_EVT_SUBSCRIBE: /* subscribe event for a request */
+			client_on_event_subscribe(protows, &rb);
+			break;
+		case CHAR_FOR_EVT_UNSUBSCRIBE: /* unsubscribe event for a request */
+			client_on_event_unsubscribe(protows, &rb);
+			break;
+		case CHAR_FOR_SUBCALL_CALL: /* subcall */
+			client_on_subcall(protows, &rb);
+			break;
+		case CHAR_FOR_DESCRIPTION: /* description */
+			client_on_description(protows, &rb);
+			break;
+		default: /* unexpected message */
+			/* TODO: close the connection */
+			break;
+		}
+		pthread_mutex_unlock(&protows->mutex);
+	}
+	free(rb.base);
+}
+
+int afb_proto_ws_client_call(
+		struct afb_proto_ws *protows,
+		const char *verb,
+		struct json_object *args,
+		const char *sessionid,
+		void *request
+)
+{
+	int rc = -1;
+	struct client_call *call;
+	struct writebuf wb = { .count = 0 };
+
+	/* allocate call data */
+	call = malloc(sizeof *call);
+	if (call == NULL) {
+		errno = ENOMEM;
+		return -1;
+	}
+	call->request = request;
+
+	/* init call data */
+	pthread_mutex_lock(&protows->mutex);
+	call->callid = ptr2id(call);
+	while(client_call_search(protows, call->callid) != NULL)
+		call->callid++;
+	call->protows = protows;
+	call->next = protows->calls;
+	protows->calls = call;
+
+	/* creates the call message */
+	if (!writebuf_char(&wb, CHAR_FOR_CALL)
+	 || !writebuf_uint32(&wb, call->callid)
+	 || !writebuf_string(&wb, verb)
+	 || !writebuf_string(&wb, sessionid)
+	 || !writebuf_object(&wb, args)) {
+		errno = EINVAL;
+		goto clean;
+	}
+
+	/* send */
+	rc = afb_ws_binary_v(protows->ws, wb.iovec, wb.count);
+	if (rc >= 0) {
+		rc = 0;
+		goto end;
+	}
+
+clean:
+	client_call_destroy(call);
+end:
+	pthread_mutex_unlock(&protows->mutex);
+	return rc;
+}
+
+/* get the description */
+int afb_proto_ws_client_describe(struct afb_proto_ws *protows, void (*callback)(void*, struct json_object*), void *closure)
+{
+	struct client_describe *desc, *d;
+	struct writebuf wb = { .count = 0 };
+
+	desc = malloc(sizeof *desc);
+	if (!desc) {
+		errno = ENOMEM;
+		goto error;
+	}
+
+	/* fill in stack the description of the task */
+	pthread_mutex_lock(&protows->mutex);
+	desc->descid = ptr2id(desc);
+	d = protows->describes;
+	while (d) {
+		if (d->descid != desc->descid)
+			d = d->next;
+		else {
+			desc->descid++;
+			d = protows->describes;
+		}
+	}
+	desc->callback = callback;
+	desc->closure = closure;
+	desc->protows = protows;
+	desc->next = protows->describes;
+	protows->describes = desc;
+	pthread_mutex_unlock(&protows->mutex);
+
+	/* send */
+	if (writebuf_char(&wb, CHAR_FOR_DESCRIBE)
+	 && writebuf_uint32(&wb, desc->descid)
+	 && afb_ws_binary_v(protows->ws, wb.iovec, wb.count) >= 0)
+		return 0;
+
+	pthread_mutex_lock(&protows->mutex);
+	d = protows->describes;
+	if (d == desc)
+		protows->describes = desc->next;
+	else {
+		while(d && d->next != desc)
+			d = d->next;
+		if (d)
+			d->next = desc->next;
+	}
+	free(desc);
+	pthread_mutex_unlock(&protows->mutex);
+error:
+	/* TODO? callback(closure, NULL); */
+	return -1;
+}
+
+/******************* client description part for server *****************************/
+
+/* on call, propagate it to the ws service */
+static void server_on_call(struct afb_proto_ws *protows, struct readbuf *rb)
+{
+	struct afb_proto_ws_call *call;
+	const char *uuid, *verb;
+	uint32_t callid;
+	size_t lenverb;
+	struct json_object *object;
+
+	afb_proto_ws_addref(protows);
+
+	/* reads the call message data */
+	if (!readbuf_uint32(rb, &callid)
+	 || !readbuf_string(rb, &verb, &lenverb)
+	 || !readbuf_string(rb, &uuid, NULL)
+	 || !readbuf_object(rb, &object))
+		goto overflow;
+
+	/* create the request */
+	call = malloc(sizeof *call);
+	if (call == NULL)
+		goto out_of_memory;
+
+	call->protows = protows;
+	call->callid = callid;
+	call->refcount = 1;
+	call->buffer = rb->base;
+	rb->base = NULL; /* don't free the buffer */
+
+	protows->server_itf->on_call(protows->closure, call, verb, object, uuid);
+	return;
+
+out_of_memory:
+	json_object_put(object);
+
+overflow:
+	afb_proto_ws_unref(protows);
+}
+
+/* on subcall reply */
+static void server_on_subcall_reply(struct afb_proto_ws *protows, struct readbuf *rb)
+{
+	char ie;
+	uint32_t subcallid;
+	struct json_object *object;
+	struct server_subcall *sc, **psc;
+
+	/* reads the call message data */
+	if (!readbuf_uint32(rb, &subcallid)
+	 || !readbuf_char(rb, &ie)
+	 || !readbuf_object(rb, &object)) {
+		/* TODO bad protocol */
+		return;
+	}
+
+	/* search the subcall and unlink it */
+	pthread_mutex_lock(&protows->mutex);
+	psc = &protows->subcalls;
+	while ((sc = *psc) && sc->subcallid != subcallid)
+		psc = &sc->next;
+	if (!sc) {
+		pthread_mutex_unlock(&protows->mutex);
+		json_object_put(object);
+		/* TODO subcall not found */
+	} else {
+		*psc = sc->next;
+		pthread_mutex_unlock(&protows->mutex);
+		sc->callback(sc->closure, -(int)ie, object);
+		free(sc);
+	}
+}
+
+static int server_send_description(struct afb_proto_ws *protows, uint32_t descid, struct json_object *descobj)
+{
+	struct writebuf wb = { .count = 0 };
+
+	return -!(writebuf_char(&wb, CHAR_FOR_DESCRIPTION)
+		 && writebuf_uint32(&wb, descid)
+		 && writebuf_object(&wb, descobj)
+	         && afb_ws_binary_v(protows->ws, wb.iovec, wb.count) >= 0);
+}
+
+int afb_proto_ws_describe_put(struct afb_proto_ws_describe *describe, struct json_object *description)
+{
+	int rc = server_send_description(describe->protows, describe->descid, description);
+	afb_proto_ws_addref(describe->protows);
+	free(describe);
+	return rc;
+}
+
+/* on describe, propagate it to the ws service */
+static void server_on_describe(struct afb_proto_ws *protows, struct readbuf *rb)
+{
+	uint32_t descid;
+	struct afb_proto_ws_describe *desc;
+
+	/* reads the descid */
+	if (readbuf_uint32(rb, &descid)) {
+		if (protows->server_itf->on_describe) {
+			/* create asynchronous job */
+			desc = malloc(sizeof *desc);
+			if (desc) {
+				desc->descid = descid;
+				desc->protows = protows;
+				afb_proto_ws_addref(protows);
+				protows->server_itf->on_describe(protows->closure, desc);
+				return;
+			}
+		}
+		server_send_description(protows, descid, NULL);
+	}
+}
+
+/* callback when receiving binary data */
+static void server_on_binary(void *closure, char *data, size_t size)
+{
+	struct afb_proto_ws *protows;
+	struct readbuf rb;
+
+	rb.base = data;
+	if (size > 0) {
+		rb.head = data;
+		rb.end = data + size;
+		protows = closure;
+
+		switch (*rb.head++) {
+		case CHAR_FOR_CALL:
+			server_on_call(protows, &rb);
+			break;
+		case CHAR_FOR_SUBCALL_REPLY:
+			server_on_subcall_reply(protows, &rb);
+			break;
+		case CHAR_FOR_DESCRIBE:
+			server_on_describe(protows, &rb);
+			break;
+		default: /* unexpected message */
+			/* TODO: close the connection */
+			break;
+		}
+	}
+	free(rb.base);
+}
+
+/******************* server part: manage events **********************************/
+
+static int server_event_send(struct afb_proto_ws *protows, char order, const char *event_name, int event_id, struct json_object *data)
+{
+	struct writebuf wb = { .count = 0 };
+
+	return -!(writebuf_char(&wb, order)
+		 && (order == CHAR_FOR_EVT_BROADCAST || writebuf_uint32(&wb, event_id))
+		 && writebuf_string(&wb, event_name)
+		 && (order == CHAR_FOR_EVT_ADD || order == CHAR_FOR_EVT_DEL || writebuf_object(&wb, data))
+		 && afb_ws_binary_v(protows->ws, wb.iovec, wb.count) >= 0);
+}
+
+int afb_proto_ws_server_event_create(struct afb_proto_ws *protows, const char *event_name, int event_id)
+{
+	return server_event_send(protows, CHAR_FOR_EVT_ADD, event_name, event_id, NULL);
+}
+
+int afb_proto_ws_server_event_remove(struct afb_proto_ws *protows, const char *event_name, int event_id)
+{
+	return server_event_send(protows, CHAR_FOR_EVT_DEL, event_name, event_id, NULL);
+}
+
+int afb_proto_ws_server_event_push(struct afb_proto_ws *protows, const char *event_name, int event_id, struct json_object *data)
+{
+	return server_event_send(protows, CHAR_FOR_EVT_PUSH, event_name, event_id, data);
+}
+
+int afb_proto_ws_server_event_broadcast(struct afb_proto_ws *protows, const char *event_name, struct json_object *data)
+{
+	return server_event_send(protows, CHAR_FOR_EVT_BROADCAST, event_name, 0, data);
+}
+
+/*****************************************************/
+
+/* callback when receiving a hangup */
+static void on_hangup(void *closure)
+{
+	struct afb_proto_ws *protows = closure;
+	struct server_subcall *sc, *nsc;
+	struct client_describe *cd, *ncd;
+
+	nsc = protows->subcalls;
+	while (nsc) {
+		sc= nsc;
+		nsc = sc->next;
+		sc->callback(sc->closure, 1, NULL);
+		free(sc);
+	}
+
+	ncd = protows->describes;
+	while (ncd) {
+		cd= ncd;
+		ncd = cd->next;
+		cd->callback(cd->closure, NULL);
+		free(cd);
+	}
+
+	if (protows->fd >= 0) {
+		protows->fd = -1;
+		if (protows->on_hangup)
+			protows->on_hangup(protows->closure);
+	}
+}
+
+/*****************************************************/
+
+static const struct afb_ws_itf proto_ws_client_ws_itf =
+{
+	.on_close = NULL,
+	.on_text = NULL,
+	.on_binary = client_on_binary,
+	.on_error = NULL,
+	.on_hangup = on_hangup
+};
+
+static const struct afb_ws_itf server_ws_itf =
+{
+	.on_close = NULL,
+	.on_text = NULL,
+	.on_binary = server_on_binary,
+	.on_error = NULL,
+	.on_hangup = on_hangup
+};
+
+/*****************************************************/
+
+static struct afb_proto_ws *afb_proto_ws_create(int fd, const struct afb_proto_ws_server_itf *itfs, const struct afb_proto_ws_client_itf *itfc, void *closure, const struct afb_ws_itf *itf)
+{
+	struct afb_proto_ws *protows;
+
+	protows = calloc(1, sizeof *protows);
+	if (protows == NULL)
+		errno = ENOMEM;
+	else {
+		fcntl(fd, F_SETFD, FD_CLOEXEC);
+		fcntl(fd, F_SETFL, O_NONBLOCK);
+		protows->ws = afb_ws_create(afb_common_get_event_loop(), fd, itf, protows);
+		if (protows->ws != NULL) {
+			protows->fd = fd;
+			protows->refcount = 1;
+			protows->subcalls = NULL;
+			protows->closure = closure;
+			protows->server_itf = itfs;
+			protows->client_itf = itfc;
+			pthread_mutex_init(&protows->mutex, NULL);
+			return protows;
+		}
+		free(protows);
+	}
+	return NULL;
+}
+
+struct afb_proto_ws *afb_proto_ws_create_client(int fd, const struct afb_proto_ws_client_itf *itf, void *closure)
+{
+	return afb_proto_ws_create(fd, NULL, itf, closure, &proto_ws_client_ws_itf);
+}
+
+struct afb_proto_ws *afb_proto_ws_create_server(int fd, const struct afb_proto_ws_server_itf *itf, void *closure)
+{
+	return afb_proto_ws_create(fd, itf, NULL, closure, &server_ws_itf);
+}
+
+void afb_proto_ws_unref(struct afb_proto_ws *protows)
+{
+	if (!__atomic_sub_fetch(&protows->refcount, 1, __ATOMIC_RELAXED)) {
+		afb_proto_ws_hangup(protows);
+		afb_ws_destroy(protows->ws);
+		pthread_mutex_destroy(&protows->mutex);
+		free(protows);
+	}
+}
+
+void afb_proto_ws_addref(struct afb_proto_ws *protows)
+{
+	__atomic_add_fetch(&protows->refcount, 1, __ATOMIC_RELAXED);
+}
+
+int afb_proto_ws_is_client(struct afb_proto_ws *protows)
+{
+	return !!protows->client_itf;
+}
+
+int afb_proto_ws_is_server(struct afb_proto_ws *protows)
+{
+	return !!protows->server_itf;
+}
+
+void afb_proto_ws_hangup(struct afb_proto_ws *protows)
+{
+	afb_ws_hangup(protows->ws);
+}
+
+void afb_proto_ws_on_hangup(struct afb_proto_ws *protows, void (*on_hangup)(void *closure))
+{
+	protows->on_hangup = on_hangup;
+}
+
diff --git a/src/afb-proto-ws.h b/src/afb-proto-ws.h
new file mode 100644
index 00000000..9cdf4902
--- /dev/null
+++ b/src/afb-proto-ws.h
@@ -0,0 +1,82 @@
+/*
+ * Copyright (C) 2016, 2017 "IoT.bzh"
+ * Author: José Bollo <jose.bollo@iot.bzh>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+
+#pragma once
+
+struct afb_proto_ws;
+struct afb_proto_ws_call;
+struct afb_proto_ws_subcall;
+struct afb_proto_ws_describe;
+
+struct afb_proto_ws_client_itf
+{  
+	void (*on_reply_success)(void *closure, void *request, struct json_object *result, const char *info);
+	void (*on_reply_fail)(void *closure, void *request, const char *status, const char *info);
+
+	void (*on_event_create)(void *closure, const char *event_name, int event_id);
+	void (*on_event_remove)(void *closure, const char *event_name, int event_id);
+	void (*on_event_subscribe)(void *closure, void *request, const char *event_name, int event_id);
+	void (*on_event_unsubscribe)(void *closure, void *request, const char *event_name, int event_id);
+	void (*on_event_push)(void *closure, const char *event_name, int event_id, struct json_object *data);
+	void (*on_event_broadcast)(void *closure, const char *event_name, struct json_object *data);
+
+	void (*on_subcall)(void *closure, struct afb_proto_ws_subcall *subcall, void *request, const char *api, const char *verb, struct json_object *args);
+};
+
+struct afb_proto_ws_server_itf
+{
+	void (*on_call)(void *closure, struct afb_proto_ws_call *call, const char *verb, struct json_object *args, const char *sessionid);
+	void (*on_describe)(void *closure, struct afb_proto_ws_describe *describe);
+};
+
+extern struct afb_proto_ws *afb_proto_ws_create_client(int fd, const struct afb_proto_ws_client_itf *itf, void *closure);
+extern struct afb_proto_ws *afb_proto_ws_create_server(int fd, const struct afb_proto_ws_server_itf *itf, void *closure);
+
+extern void afb_proto_ws_unref(struct afb_proto_ws *protows);
+extern void afb_proto_ws_addref(struct afb_proto_ws *protows);
+
+extern int afb_proto_ws_is_client(struct afb_proto_ws *protows);
+extern int afb_proto_ws_is_server(struct afb_proto_ws *protows);
+
+extern void afb_proto_ws_hangup(struct afb_proto_ws *protows);
+extern void afb_proto_ws_on_hangup(struct afb_proto_ws *protows, void (*on_hangup)(void *closure));
+
+
+
+extern int afb_proto_ws_client_call(struct afb_proto_ws *protows, const char *verb, struct json_object *args, const char *sessionid, void *request);
+extern int afb_proto_ws_client_describe(struct afb_proto_ws *protows, void (*callback)(void*, struct json_object*), void *closure);
+
+extern int afb_proto_ws_server_event_create(struct afb_proto_ws *protows, const char *event_name, int event_id);
+extern int afb_proto_ws_server_event_remove(struct afb_proto_ws *protows, const char *event_name, int event_id);
+extern int afb_proto_ws_server_event_push(struct afb_proto_ws *protows, const char *event_name, int event_id, struct json_object *data);
+extern int afb_proto_ws_server_event_broadcast(struct afb_proto_ws *protows, const char *event_name, struct json_object *data);
+
+extern void afb_proto_ws_call_addref(struct afb_proto_ws_call *call);
+extern void afb_proto_ws_call_unref(struct afb_proto_ws_call *call);
+
+extern int afb_proto_ws_call_success(struct afb_proto_ws_call *call, struct json_object *obj, const char *info);
+extern int afb_proto_ws_call_fail(struct afb_proto_ws_call *call, const char *status, const char *info);
+
+extern int afb_proto_ws_call_subcall(struct afb_proto_ws_call *call, const char *api, const char *verb, struct json_object *args, void (*callback)(void*, int, struct json_object*), void *cb_closure);
+extern int afb_proto_ws_call_subscribe(struct afb_proto_ws_call *call, const char *event_name, int event_id);
+extern int afb_proto_ws_call_unsubscribe(struct afb_proto_ws_call *call, const char *event_name, int event_id);
+
+extern int afb_proto_ws_subcall_reply(struct afb_proto_ws_subcall *subcall, int status, struct json_object *result);
+
+extern int afb_proto_ws_describe_put(struct afb_proto_ws_describe *describe, struct json_object *description);
+
diff --git a/src/afb-stub-ws.c b/src/afb-stub-ws.c
index cb52923d..1f0a3e68 100644
--- a/src/afb-stub-ws.c
+++ b/src/afb-stub-ws.c
@@ -41,10 +41,9 @@
 
 #include "afb-session.h"
 #include "afb-cred.h"
-#include "afb-ws.h"
-#include "afb-msg-json.h"
 #include "afb-api.h"
 #include "afb-apiset.h"
+#include "afb-proto-ws.h"
 #include "afb-stub-ws.h"
 #include "afb-context.h"
 #include "afb-evt.h"
@@ -54,21 +53,6 @@
 
 struct afb_stub_ws;
 
-/************** constants for protocol definition *************************/
-
-#define CHAR_FOR_CALL             'C'
-#define CHAR_FOR_ANSWER_SUCCESS   'T'
-#define CHAR_FOR_ANSWER_FAIL      'F'
-#define CHAR_FOR_EVT_BROADCAST    '*'
-#define CHAR_FOR_EVT_ADD          '+'
-#define CHAR_FOR_EVT_DEL          '-'
-#define CHAR_FOR_EVT_PUSH         '!'
-#define CHAR_FOR_EVT_SUBSCRIBE    'S'
-#define CHAR_FOR_EVT_UNSUBSCRIBE  'U'
-#define CHAR_FOR_SUBCALL_CALL     'B'
-#define CHAR_FOR_SUBCALL_REPLY    'R'
-#define CHAR_FOR_DESCRIBE         'D'
-#define CHAR_FOR_DESCRIPTION      'd'
 
 /******************* handling subcalls *****************************/
 
@@ -109,7 +93,7 @@ struct client_call {
 struct server_req {
 	struct afb_xreq xreq;		/* the xreq */
 	struct afb_stub_ws *stubws;	/* the client of the request */
-	uint32_t msgid;			/* the incoming request msgid */
+	struct afb_proto_ws_call *call;	/* the incoming call */
 };
 
 /*
@@ -128,11 +112,9 @@ struct client_event
  */
 struct client_describe
 {
-	struct client_describe *next;
 	struct afb_stub_ws *stubws;
 	struct jobloop *jobloop;
 	struct json_object *result;
-	uint32_t descid;
 };
 
 /*
@@ -141,7 +123,7 @@ struct client_describe
 struct server_describe
 {
 	struct afb_stub_ws *stubws;
-	uint32_t descid;
+	struct afb_proto_ws_describe *describe;
 };
 
 /******************* stub description for client or servers ******************/
@@ -151,14 +133,11 @@ struct afb_stub_ws
 	/* count of references */
 	int refcount;
 
-	/* file descriptor */
-	int fd;
-
 	/* resource control */
 	pthread_mutex_t mutex;
 
-	/* websocket */
-	struct afb_ws *ws;
+	/* protocol */
+	struct afb_proto_ws *proto;
 
 	/* listener for events (server side) */
 	struct afb_evt_listener *listener;
@@ -166,18 +145,9 @@ struct afb_stub_ws
 	/* event replica (client side) */
 	struct client_event *events;
 
-	/* emitted calls (client side) */
-	struct client_call *calls;
-
 	/* credentials (server side) */
 	struct afb_cred *cred;
 
-	/* pending subcalls (server side) */
-	struct server_subcall *subcalls;
-
-	/* pending description (client side) */
-	struct client_describe *describes;
-
 	/* apiset */
 	struct afb_apiset *apiset;
 
@@ -188,138 +158,6 @@ struct afb_stub_ws
 	char apiname[1];
 };
 
-/******************* common useful tools **********************************/
-
-/**
- * translate a pointer to some integer
- * @param ptr the pointer to translate
- * @return an integer
- */
-static inline uint32_t ptr2id(void *ptr)
-{
-	return (uint32_t)(((intptr_t)ptr) >> 6);
-}
-
-/******************* serialisation part **********************************/
-
-struct readbuf
-{
-	char *head, *end;
-};
-
-#define WRITEBUF_COUNT_MAX  32
-struct writebuf
-{
-	struct iovec iovec[WRITEBUF_COUNT_MAX];
-	uint32_t uints[WRITEBUF_COUNT_MAX];
-	int count;
-};
-
-static char *readbuf_get(struct readbuf *rb, uint32_t length)
-{
-	char *before = rb->head;
-	char *after = before + length;
-	if (after > rb->end)
-		return 0;
-	rb->head = after;
-	return before;
-}
-
-static int readbuf_char(struct readbuf *rb, char *value)
-{
-	if (rb->head >= rb->end)
-		return 0;
-	*value = *rb->head++;
-	return 1;
-}
-
-static int readbuf_uint32(struct readbuf *rb, uint32_t *value)
-{
-	char *after = rb->head + sizeof *value;
-	if (after > rb->end)
-		return 0;
-	memcpy(value, rb->head, sizeof *value);
-	rb->head = after;
-	*value = le32toh(*value);
-	return 1;
-}
-
-static int readbuf_string(struct readbuf *rb, const char **value, size_t *length)
-{
-	uint32_t len;
-	if (!readbuf_uint32(rb, &len) || !len)
-		return 0;
-	if (length)
-		*length = (size_t)(len - 1);
-	return (*value = readbuf_get(rb, len)) != NULL &&  rb->head[-1] == 0;
-}
-
-static int readbuf_object(struct readbuf *rb, struct json_object **object)
-{
-	const char *string;
-	struct json_object *o;
-	int rc = readbuf_string(rb, &string, NULL);
-	if (rc) {
-		o = json_tokener_parse(string);
-		if (o == NULL && strcmp(string, "null"))
-			o = json_object_new_string(string);
-		*object = o;
-	}
-	return rc;
-}
-
-static int writebuf_put(struct writebuf *wb, const void *value, size_t length)
-{
-	int i = wb->count;
-	if (i == WRITEBUF_COUNT_MAX)
-		return 0;
-	wb->iovec[i].iov_base = (void*)value;
-	wb->iovec[i].iov_len = length;
-	wb->count = i + 1;
-	return 1;
-}
-
-static int writebuf_char(struct writebuf *wb, char value)
-{
-	int i = wb->count;
-	if (i == WRITEBUF_COUNT_MAX)
-		return 0;
-	*(char*)&wb->uints[i] = value;
-	wb->iovec[i].iov_base = &wb->uints[i];
-	wb->iovec[i].iov_len = 1;
-	wb->count = i + 1;
-	return 1;
-}
-
-static int writebuf_uint32(struct writebuf *wb, uint32_t value)
-{
-	int i = wb->count;
-	if (i == WRITEBUF_COUNT_MAX)
-		return 0;
-	wb->uints[i] = htole32(value);
-	wb->iovec[i].iov_base = &wb->uints[i];
-	wb->iovec[i].iov_len = sizeof wb->uints[i];
-	wb->count = i + 1;
-	return 1;
-}
-
-static int writebuf_string_length(struct writebuf *wb, const char *value, size_t length)
-{
-	uint32_t len = (uint32_t)++length;
-	return (size_t)len == length && len && writebuf_uint32(wb, len) && writebuf_put(wb, value, length);
-}
-
-static int writebuf_string(struct writebuf *wb, const char *value)
-{
-	return writebuf_string_length(wb, value, strlen(value));
-}
-
-static int writebuf_object(struct writebuf *wb, struct json_object *object)
-{
-	const char *string = json_object_to_json_string_ext(object, JSON_C_TO_STRING_PLAIN);
-	return string != NULL && writebuf_string(wb, string);
-}
-
 /******************* ws request part for server *****************/
 
 /* decrement the reference count of the request and free/release it on falling to null */
@@ -330,6 +168,7 @@ static void server_req_destroy_cb(struct afb_xreq *xreq)
 	afb_context_disconnect(&wreq->xreq.context);
 	afb_cred_unref(wreq->xreq.cred);
 	json_object_put(wreq->xreq.json);
+	afb_proto_ws_call_unref(wreq->call);
 	afb_stub_ws_unref(wreq->stubws);
 	free(wreq);
 }
@@ -337,122 +176,58 @@ static void server_req_destroy_cb(struct afb_xreq *xreq)
 static void server_req_success_cb(struct afb_xreq *xreq, struct json_object *obj, const char *info)
 {
 	int rc;
-	struct writebuf wb = { .count = 0 };
 	struct server_req *wreq = CONTAINER_OF_XREQ(struct server_req, xreq);
 
-	if (writebuf_char(&wb, CHAR_FOR_ANSWER_SUCCESS)
-	 && writebuf_uint32(&wb, wreq->msgid)
-	 && writebuf_uint32(&wb, (uint32_t)wreq->xreq.context.flags)
-	 && writebuf_string(&wb, info ? : "")
-	 && writebuf_object(&wb, obj)) {
-		rc = afb_ws_binary_v(wreq->stubws->ws, wb.iovec, wb.count);
-		if (rc >= 0)
-			goto success;
-	}
-	ERROR("error while sending success");
-success:
+	rc = afb_proto_ws_call_success(wreq->call, obj, info);
+	if (rc < 0)
+		ERROR("error while sending success");
 	json_object_put(obj);
 }
 
 static void server_req_fail_cb(struct afb_xreq *xreq, const char *status, const char *info)
 {
 	int rc;
-	struct writebuf wb = { .count = 0 };
 	struct server_req *wreq = CONTAINER_OF_XREQ(struct server_req, xreq);
 
-	if (writebuf_char(&wb, CHAR_FOR_ANSWER_FAIL)
-	 && writebuf_uint32(&wb, wreq->msgid)
-	 && writebuf_uint32(&wb, (uint32_t)wreq->xreq.context.flags)
-	 && writebuf_string(&wb, status)
-	 && writebuf_string(&wb, info ? : "")) {
-		rc = afb_ws_binary_v(wreq->stubws->ws, wb.iovec, wb.count);
-		if (rc >= 0)
-			return;
-	}
-	ERROR("error while sending fail");
+	rc = afb_proto_ws_call_fail(wreq->call, status, info);
+	if (rc < 0)
+		ERROR("error while sending fail");
 }
 
 static void server_req_subcall_cb(struct afb_xreq *xreq, const char *api, const char *verb, struct json_object *args, void (*callback)(void*, int, struct json_object*), void *cb_closure)
 {
 	int rc;
-	struct writebuf wb = { .count = 0 };
-	struct server_subcall *sc, *osc;
 	struct server_req *wreq = CONTAINER_OF_XREQ(struct server_req, xreq);
-	struct afb_stub_ws *stubws = wreq->stubws;
-
-	sc = malloc(sizeof *sc);
-	if (!sc) {
-		callback(cb_closure, 1, afb_msg_json_internal_error());
-	} else {
-		sc->callback = callback;
-		sc->closure = cb_closure;
-
-		pthread_mutex_unlock(&stubws->mutex);
-		sc->subcallid = ptr2id(sc);
-		do {
-			sc->subcallid++;
-			osc = stubws->subcalls;
-			while(osc && osc->subcallid != sc->subcallid)
-				osc = osc->next;
-		} while (osc);
-		sc->next = stubws->subcalls;
-		stubws->subcalls = sc;
-		pthread_mutex_unlock(&stubws->mutex);
-
-		if (writebuf_char(&wb, CHAR_FOR_SUBCALL_CALL)
-		 && writebuf_uint32(&wb, wreq->msgid)
-		 && writebuf_uint32(&wb, sc->subcallid)
-		 && writebuf_string(&wb, api)
-		 && writebuf_string(&wb, verb)
-		 && writebuf_object(&wb, args)) {
-			rc = afb_ws_binary_v(wreq->stubws->ws, wb.iovec, wb.count);
-			if (rc >= 0)
-				return;
-		}
-		ERROR("error while sending fail");
-	}
+
+	rc = afb_proto_ws_call_subcall(wreq->call, api, verb, args, callback, cb_closure);
+	if (rc < 0)
+		ERROR("error while sending subcall");
 }
 
 static int server_req_subscribe_cb(struct afb_xreq *xreq, struct afb_event event)
 {
-	int rc, rc2;
-	struct writebuf wb = { .count = 0 };
+	int rc;
 	struct server_req *wreq = CONTAINER_OF_XREQ(struct server_req, xreq);
 
 	rc = afb_evt_add_watch(wreq->stubws->listener, event);
+	if (rc >= 0)
+		rc = afb_proto_ws_call_subscribe(wreq->call,  afb_evt_event_name(event), afb_evt_event_id(event));
 	if (rc < 0)
-		return rc;
-
-	if (writebuf_char(&wb, CHAR_FOR_EVT_SUBSCRIBE)
-	 && writebuf_uint32(&wb, wreq->msgid)
-	 && writebuf_uint32(&wb, (uint32_t)afb_evt_event_id(event))
-	 && writebuf_string(&wb, afb_evt_event_name(event))) {
-		rc2 = afb_ws_binary_v(wreq->stubws->ws, wb.iovec, wb.count);
-		if (rc2 >= 0)
-			goto success;
-	}
-	ERROR("error while subscribing event");
-success:
+		ERROR("error while subscribing event");
 	return rc;
 }
 
 static int server_req_unsubscribe_cb(struct afb_xreq *xreq, struct afb_event event)
 {
 	int rc, rc2;
-	struct writebuf wb = { .count = 0 };
 	struct server_req *wreq = CONTAINER_OF_XREQ(struct server_req, xreq);
 
-	if (writebuf_char(&wb, CHAR_FOR_EVT_UNSUBSCRIBE)
-	 && writebuf_uint32(&wb, wreq->msgid)
-	 && writebuf_uint32(&wb, (uint32_t)afb_evt_event_id(event))
-	 && writebuf_string(&wb, afb_evt_event_name(event))) {
-		rc2 = afb_ws_binary_v(wreq->stubws->ws, wb.iovec, wb.count);
-		if (rc2 >= 0)
-			goto success;
-	}
-	ERROR("error while subscribing event");
-success:
-	rc = afb_evt_remove_watch(wreq->stubws->listener, event);
+	rc = afb_proto_ws_call_unsubscribe(wreq->call,  afb_evt_event_name(event), afb_evt_event_id(event));
+	rc2 = afb_evt_remove_watch(wreq->stubws->listener, event);
+	if (rc >= 0 && rc2 < 0)
+		rc = rc2;
+	if (rc < 0)
+		ERROR("error while unsubscribing event");
 	return rc;
 }
 
@@ -467,18 +242,6 @@ static const struct afb_xreq_query_itf server_req_xreq_itf = {
 
 /******************* client part **********************************/
 
-/* search a memorized call */
-static struct client_call *client_call_search(struct afb_stub_ws *stubws, uint32_t msgid)
-{
-	struct client_call *call;
-
-	call = stubws->calls;
-	while (call != NULL && call->msgid != msgid)
-		call = call->next;
-
-	return call;
-}
-
 /* search the event */
 static struct client_event *client_event_search(struct afb_stub_ws *stubws, uint32_t eventid, const char *name)
 {
@@ -491,116 +254,104 @@ static struct client_event *client_event_search(struct afb_stub_ws *stubws, uint
 	return ev;
 }
 
+/* on call, propagate it to the ws service */
+static void client_call_cb(void * closure, struct afb_xreq *xreq)
+{
+	struct afb_stub_ws *stubws = closure;
+
+	afb_proto_ws_client_call(stubws->proto, xreq->verb, afb_xreq_json(xreq), afb_session_uuid(xreq->context.session), xreq);
+	afb_xreq_addref(xreq);
+}
 
-/* allocates and init the memorizing call */
-static struct client_call *client_call_make(struct afb_stub_ws *stubws, struct afb_xreq *xreq)
+static void client_on_description_cb(void *closure, struct json_object *data)
 {
-	struct client_call *call;
-
-	call = malloc(sizeof *call);
-	if (call != NULL) {
-		afb_xreq_addref(xreq);
-		call->xreq = xreq;
-		call->msgid = ptr2id(call);
-		while(client_call_search(stubws, call->msgid) != NULL)
-			call->msgid++;
-		call->stubws = stubws;
-		call->next = stubws->calls;
-		stubws->calls = call;
-	}
-	return call;
+	struct client_describe *desc = closure;
+
+	desc->result = data;
+	jobs_leave(desc->jobloop);
 }
 
-/* free and release the memorizing call */
-static void client_call_destroy(struct client_call *call)
+static void client_send_describe_cb(int signum, void *closure, struct jobloop *jobloop)
 {
-	struct client_call **prv;
+	struct client_describe *desc = closure;
 
-	prv = &call->stubws->calls;
-	while (*prv != NULL) {
-		if (*prv == call) {
-			*prv = call->next;
-			break;
-		}
-		prv = &(*prv)->next;
+	if (signum)
+		jobs_leave(jobloop);
+	else {
+		desc->jobloop = jobloop;
+		afb_proto_ws_client_describe(desc->stubws->proto, client_on_description_cb, desc);
 	}
+}
+
+/* get the description */
+static struct json_object *client_describe_cb(void * closure)
+{
+	struct client_describe desc;
 
-	afb_xreq_unref(call->xreq);
-	free(call);
+	/* synchronous job: send the request and wait its result */
+	desc.stubws = closure;
+	desc.result = NULL;
+	jobs_enter(NULL, 0, client_send_describe_cb, &desc);
+	return desc.result;
 }
 
-/* get event data from the message */
-static int client_msg_event_read(struct readbuf *rb, uint32_t *eventid, const char **name)
+/******************* server part: manage events **********************************/
+
+static void server_event_add(void *closure, const char *event, int eventid)
 {
-	return readbuf_uint32(rb, eventid) && readbuf_string(rb, name, NULL);
+	struct afb_stub_ws *stubws = closure;
+
+	afb_proto_ws_server_event_create(stubws->proto, event, eventid);
 }
 
-/* get event from the message */
-static int client_msg_event_get(struct afb_stub_ws *stubws, struct readbuf *rb, struct client_event **ev)
+static void server_event_remove(void *closure, const char *event, int eventid)
 {
-	const char *name;
-	uint32_t eventid;
+	struct afb_stub_ws *stubws = closure;
 
-	/* get event data from the message */
-	if (!client_msg_event_read(rb, &eventid, &name)) {
-		ERROR("Invalid message");
-		return 0;
-	}
+	afb_proto_ws_server_event_remove(stubws->proto, event, eventid);
+}
 
-	/* check conflicts */
-	*ev = client_event_search(stubws, eventid, name);
-	if (*ev == NULL) {
-		ERROR("event %s not found", name);
-		return 0;
-	}
+static void server_event_push(void *closure, const char *event, int eventid, struct json_object *object)
+{
+	struct afb_stub_ws *stubws = closure;
 
-	return 1;
+	afb_proto_ws_server_event_push(stubws->proto, event, eventid, object);
+	json_object_put(object);
 }
 
-/* get event from the message */
-static int client_msg_call_get(struct afb_stub_ws *stubws, struct readbuf *rb, struct client_call **call)
+static void server_event_broadcast(void *closure, const char *event, int eventid, struct json_object *object)
 {
-	uint32_t msgid;
+	struct afb_stub_ws *stubws = closure;
 
-	/* get event data from the message */
-	if (!readbuf_uint32(rb, &msgid)) {
-		ERROR("Invalid message");
-		return 0;
-	}
+	afb_proto_ws_server_event_broadcast(stubws->proto, event, object);
+	json_object_put(object);
+}
 
-	/* get the call */
-	*call = client_call_search(stubws, msgid);
-	if (*call == NULL) {
-		ERROR("message not found");
-		return 0;
-	}
+/*****************************************************/
+
+static void on_reply_success(void *closure, void *request, struct json_object *result, const char *info)
+{
+	struct afb_xreq *xreq = request;
 
-	return 1;
+	afb_xreq_success(xreq, result, *info ? info : NULL);
+	afb_xreq_unref(xreq);
 }
 
-/* read a subscrition message */
-static int client_msg_subscription_get(struct afb_stub_ws *stubws, struct readbuf *rb, struct client_call **call, struct client_event **ev)
+static void on_reply_fail(void *closure, void *request, const char *status, const char *info)
 {
-	return client_msg_call_get(stubws, rb, call) && client_msg_event_get(stubws, rb, ev);
+	struct afb_xreq *xreq = request;
+
+	afb_xreq_fail(xreq, status, *info ? info : NULL);
+	afb_xreq_unref(xreq);
 }
 
-/* adds an event */
-static void client_event_create(struct afb_stub_ws *stubws, struct readbuf *rb)
+static void on_event_create(void *closure, const char *event_name, int event_id)
 {
-	size_t offset;
-	const char *name;
-	uint32_t eventid;
+	struct afb_stub_ws *stubws = closure;
 	struct client_event *ev;
 
-	/* get event data from the message */
-	offset = client_msg_event_read(rb, &eventid, &name);
-	if (offset == 0) {
-		ERROR("Invalid message");
-		return;
-	}
-
 	/* check conflicts */
-	ev = client_event_search(stubws, eventid, name);
+	ev = client_event_search(stubws, event_id, event_name);
 	if (ev != NULL) {
 		ev->refcount++;
 		return;
@@ -609,27 +360,27 @@ static void client_event_create(struct afb_stub_ws *stubws, struct readbuf *rb)
 	/* no conflict, try to add it */
 	ev = malloc(sizeof *ev);
 	if (ev != NULL) {
-		ev->event = afb_evt_create_event(name);
-		if (ev->event.closure == NULL)
-			free(ev);
-		else {
+		ev->event = afb_evt_create_event(event_name);
+		if (ev->event.closure != NULL) {
 			ev->refcount = 1;
-			ev->eventid = eventid;
+			ev->eventid = event_id;
 			ev->next = stubws->events;
 			stubws->events = ev;
 			return;
 		}
+		free(ev);
 	}
-	ERROR("can't create event %s, out of memory", name);
+	ERROR("can't create event %s, out of memory", event_name);
 }
 
-/* removes an event */
-static void client_event_drop(struct afb_stub_ws *stubws, struct readbuf *rb)
+static void on_event_remove(void *closure, const char *event_name, int event_id)
 {
+	struct afb_stub_ws *stubws = closure;
 	struct client_event *ev, **prv;
 
-	/* retrieves the event */
-	if (!client_msg_event_get(stubws, rb, &ev))
+	/* check conflicts */
+	ev = client_event_search(stubws, event_id, event_name);
+	if (ev == NULL)
 		return;
 
 	/* decrease the reference count */
@@ -647,444 +398,107 @@ static void client_event_drop(struct afb_stub_ws *stubws, struct readbuf *rb)
 	free(ev);
 }
 
-/* subscribes an event */
-static void client_event_subscribe(struct afb_stub_ws *stubws, struct readbuf *rb)
+static void on_event_subscribe(void *closure, void *request, const char *event_name, int event_id)
 {
+	struct afb_stub_ws *stubws = closure;
+	struct afb_xreq *xreq = request;
 	struct client_event *ev;
-	struct client_call *call;
 
-	if (client_msg_subscription_get(stubws, rb, &call, &ev)) {
-		/* subscribe the request from the event */
-		if (afb_xreq_subscribe(call->xreq, ev->event) < 0)
-			ERROR("can't subscribe: %m");
-	}
+	/* check conflicts */
+	ev = client_event_search(stubws, event_id, event_name);
+	if (ev == NULL)
+		return;
+
+	if (afb_xreq_subscribe(xreq, ev->event) < 0)
+		ERROR("can't subscribe: %m");
 }
 
-/* unsubscribes an event */
-static void client_event_unsubscribe(struct afb_stub_ws *stubws, struct readbuf *rb)
+static void on_event_unsubscribe(void *closure, void *request, const char *event_name, int event_id)
 {
+	struct afb_stub_ws *stubws = closure;
+	struct afb_xreq *xreq = request;
 	struct client_event *ev;
-	struct client_call *call;
 
-	if (client_msg_subscription_get(stubws, rb, &call, &ev)) {
-		/* unsubscribe the request from the event */
-		if (afb_xreq_unsubscribe(call->xreq, ev->event) < 0)
-			ERROR("can't unsubscribe: %m");
-	}
-}
-
-/* receives broadcasted events */
-static void client_event_broadcast(struct afb_stub_ws *stubws, struct readbuf *rb)
-{
-	struct json_object *object;
-	const char *event;
+	/* check conflicts */
+	ev = client_event_search(stubws, event_id, event_name);
+	if (ev == NULL)
+		return;
 
-	if (readbuf_string(rb, &event, NULL) && readbuf_object(rb, &object))
-		afb_evt_broadcast(event, object);
-	else
-		ERROR("unreadable broadcasted event");
+	if (afb_xreq_unsubscribe(xreq, ev->event) < 0)
+		ERROR("can't unsubscribe: %m");
 }
 
-/* pushs an event */
-static void client_event_push(struct afb_stub_ws *stubws, struct readbuf *rb)
+static void on_event_push(void *closure, const char *event_name, int event_id, struct json_object *data)
 {
+	struct afb_stub_ws *stubws = closure;
 	struct client_event *ev;
-	struct json_object *object;
 
-	if (client_msg_event_get(stubws, rb, &ev) && readbuf_object(rb, &object))
-		afb_event_push(ev->event, object);
+	/* check conflicts */
+	ev = client_event_search(stubws, event_id, event_name);
+	if (ev)
+		afb_event_push(ev->event, data);
 	else
 		ERROR("unreadable push event");
 }
 
-static void client_reply_success(struct afb_stub_ws *stubws, struct readbuf *rb)
-{
-	struct client_call *call;
-	struct json_object *object;
-	const char *info;
-	uint32_t flags;
-
-	/* retrieve the message data */
-	if (!client_msg_call_get(stubws, rb, &call))
-		return;
-
-	if (readbuf_uint32(rb, &flags)
-	 && readbuf_string(rb, &info, NULL)
-	 && readbuf_object(rb, &object)) {
-		call->xreq->context.flags = (unsigned)flags;
-		afb_xreq_success(call->xreq, object, *info ? info : NULL);
-	} else {
-		/* failing to have the answer */
-		afb_xreq_fail(call->xreq, "error", "ws error");
-	}
-	client_call_destroy(call);
-}
-
-static void client_reply_fail(struct afb_stub_ws *stubws, struct readbuf *rb)
-{
-	struct client_call *call;
-	const char *info, *status;
-	uint32_t flags;
-
-	/* retrieve the message data */
-	if (!client_msg_call_get(stubws, rb, &call))
-		return;
-
-	if (readbuf_uint32(rb, &flags)
-	 && readbuf_string(rb, &status, NULL)
-	 && readbuf_string(rb, &info, NULL)) {
-		call->xreq->context.flags = (unsigned)flags;
-		afb_xreq_fail(call->xreq, status, *info ? info : NULL);
-	} else {
-		/* failing to have the answer */
-		afb_xreq_fail(call->xreq, "error", "ws error");
-	}
-	client_call_destroy(call);
-}
-
-/* send a subcall reply */
-static void client_send_subcall_reply(struct client_subcall *subcall, int status, json_object *object)
+static void on_event_broadcast(void *closure, const char *event_name, struct json_object *data)
 {
-	int rc;
-	struct writebuf wb = { .count = 0 };
-	char ie = status < 0;
-
-	if (!writebuf_char(&wb, CHAR_FOR_SUBCALL_REPLY)
-	 || !writebuf_uint32(&wb, subcall->subcallid)
-	 || !writebuf_char(&wb, ie)
-	 || !writebuf_object(&wb, object)) {
-		/* write error ? */
-		return;
-	}
-
-	rc = afb_ws_binary_v(subcall->stubws->ws, wb.iovec, wb.count);
-	if (rc >= 0)
-		return;
-	ERROR("error while sending subcall reply");
+	afb_evt_broadcast(event_name, data);
 }
 
-/* callback for subcall reply */
 static void client_subcall_reply_cb(void *closure, int status, json_object *object)
 {
-	client_send_subcall_reply(closure, status, object);
-	free(closure);
-}
-
-/* received a subcall request */
-static void client_subcall(struct afb_stub_ws *stubws, struct readbuf *rb)
-{
-	struct client_subcall *subcall;
-	struct client_call *call;
-	const char *api, *verb;
-	uint32_t subcallid;
-	struct json_object *object;
-
-	subcall = malloc(sizeof *subcall);
-	if (!subcall)
-		return;
-
-	/* retrieve the message data */
-	if (!client_msg_call_get(stubws, rb, &call))
-		return;
-
-	if (readbuf_uint32(rb, &subcallid)
-	 && readbuf_string(rb, &api, NULL)
-	 && readbuf_string(rb, &verb, NULL)
-	 && readbuf_object(rb, &object)) {
-		subcall->stubws = stubws;
-		subcall->subcallid = subcallid;
-		afb_xreq_subcall(call->xreq, api, verb, object, client_subcall_reply_cb, subcall);
-	}
+	struct afb_proto_ws_subcall *subcall = closure;
+	afb_proto_ws_subcall_reply(subcall, status, object);
 }
 
-/* pushs an event */
-static void client_on_description(struct afb_stub_ws *stubws, struct readbuf *rb)
+static void on_subcall(void *closure, struct afb_proto_ws_subcall *subcall, void *request, const char *api, const char *verb, struct json_object *args)
 {
-	uint32_t descid;
-	struct client_describe *desc;
-	struct json_object *object;
-
-	if (!readbuf_uint32(rb, &descid))
-		ERROR("unreadable description");
-	else {
-		desc = stubws->describes;
-		while (desc && desc->descid != descid)
-			desc = desc->next;
-		if (desc == NULL)
-			ERROR("unexpected description");
-		else {
-			if (readbuf_object(rb, &object))
-				desc->result = object;
-			else
-				ERROR("bad description");
-			jobs_leave(desc->jobloop);
-		}
-	}
-}
-
-/* callback when receiving binary data */
-static void client_on_binary(void *closure, char *data, size_t size)
-{
-	if (size > 0) {
-		struct afb_stub_ws *stubws = closure;
-		struct readbuf rb = { .head = data, .end = data + size };
-
-		pthread_mutex_lock(&stubws->mutex);
-		switch (*rb.head++) {
-		case CHAR_FOR_ANSWER_SUCCESS: /* success */
-			client_reply_success(stubws, &rb);
-			break;
-		case CHAR_FOR_ANSWER_FAIL: /* fail */
-			client_reply_fail(stubws, &rb);
-			break;
-		case CHAR_FOR_EVT_BROADCAST: /* broadcast */
-			client_event_broadcast(stubws, &rb);
-			break;
-		case CHAR_FOR_EVT_ADD: /* creates the event */
-			client_event_create(stubws, &rb);
-			break;
-		case CHAR_FOR_EVT_DEL: /* drops the event */
-			client_event_drop(stubws, &rb);
-			break;
-		case CHAR_FOR_EVT_PUSH: /* pushs the event */
-			client_event_push(stubws, &rb);
-			break;
-		case CHAR_FOR_EVT_SUBSCRIBE: /* subscribe event for a request */
-			client_event_subscribe(stubws, &rb);
-			break;
-		case CHAR_FOR_EVT_UNSUBSCRIBE: /* unsubscribe event for a request */
-			client_event_unsubscribe(stubws, &rb);
-			break;
-		case CHAR_FOR_SUBCALL_CALL: /* subcall */
-			client_subcall(stubws, &rb);
-			break;
-		case CHAR_FOR_DESCRIPTION: /* description */
-			client_on_description(stubws, &rb);
-			break;
-		default: /* unexpected message */
-			/* TODO: close the connection */
-			break;
-		}
-		pthread_mutex_unlock(&stubws->mutex);
-	}
-	free(data);
-}
-
-/* on call, propagate it to the ws service */
-static void client_call_cb(void * closure, struct afb_xreq *xreq)
-{
-	int rc;
-	struct client_call *call;
-	struct writebuf wb = { .count = 0 };
-	const char *raw;
-	size_t szraw;
-	struct afb_stub_ws *stubws = closure;
-
-	pthread_mutex_lock(&stubws->mutex);
-
-	/* create the recording data */
-	call = client_call_make(stubws, xreq);
-	if (call == NULL) {
-		afb_xreq_fail_f(xreq, "error", "out of memory");
-		goto end;
-	}
-
-	/* creates the call message */
-	raw = afb_xreq_raw(xreq, &szraw);
-	if (raw == NULL)
-		goto internal_error;
-	if (!writebuf_char(&wb, CHAR_FOR_CALL)
-	 || !writebuf_uint32(&wb, call->msgid)
-	 || !writebuf_uint32(&wb, (uint32_t)xreq->context.flags)
-	 || !writebuf_string(&wb, xreq->verb)
-	 || !writebuf_string(&wb, afb_session_uuid(xreq->context.session))
-	 || !writebuf_string_length(&wb, raw, szraw))
-		goto overflow;
-
-	/* send */
-	rc = afb_ws_binary_v(stubws->ws, wb.iovec, wb.count);
-	if (rc >= 0)
-		goto end;
-
-	afb_xreq_fail(xreq, "error", "websocket sending error");
-	goto clean_call;
+	struct afb_xreq *xreq = request;
 
-internal_error:
-	afb_xreq_fail(xreq, "error", "internal: raw is NULL!");
-	goto clean_call;
-
-overflow:
-	afb_xreq_fail(xreq, "error", "overflow: size doesn't match 32 bits!");
-
-clean_call:
-	client_call_destroy(call);
-end:
-	pthread_mutex_unlock(&stubws->mutex);
+	afb_xreq_subcall(xreq, api, verb, args, client_subcall_reply_cb, subcall);
 }
 
-static void client_send_describe_cb(int signum, void *closure, struct jobloop *jobloop)
-{
-	struct client_describe *desc = closure;
-	struct writebuf wb = { .count = 0 };
-
-	if (!signum) {
-		/* record the jobloop */
-		desc->jobloop = jobloop;
-
-		/* send */
-		if (writebuf_char(&wb, CHAR_FOR_DESCRIBE)
-		 && writebuf_uint32(&wb, desc->descid)
-		 && afb_ws_binary_v(desc->stubws->ws, wb.iovec, wb.count) >= 0)
-			return;
-	}
-	jobs_leave(jobloop);
-}
+/*****************************************************/
 
-/* get the description */
-static struct json_object *client_describe_cb(void * closure)
+static void on_call(void *closure, struct afb_proto_ws_call *call, const char *verb, struct json_object *args, const char *sessionid)
 {
-	struct client_describe desc, *d;
 	struct afb_stub_ws *stubws = closure;
-
-	/* fill in stack the description of the task */
-	pthread_mutex_lock(&stubws->mutex);
-	desc.result = NULL;
-	desc.descid = ptr2id(&desc);
-	d = stubws->describes;
-	while (d) {
-		if (d->descid != desc.descid)
-			d = d->next;
-		else {
-			desc.descid++;
-			d = stubws->describes;
-		}
-	}
-	desc.stubws = stubws;
-	desc.next = stubws->describes;
-	stubws->describes = &desc;
-	pthread_mutex_unlock(&stubws->mutex);
-
-	/* synchronous job: send the request and wait its result */
-	jobs_enter(NULL, 0, client_send_describe_cb, &desc);
-
-	/* unlink and send the result */
-	pthread_mutex_lock(&stubws->mutex);
-	d = stubws->describes;
-	if (d == &desc)
-		stubws->describes = desc.next;
-	else {
-		while (d) {
-			if (d->next != &desc)
-				d = d->next;
-			else {
-				d->next = desc.next;
-				d = NULL;
-			}
-		}
-	}
-	pthread_mutex_unlock(&stubws->mutex);
-	return desc.result;
-}
-
-/******************* client description part for server *****************************/
-
-/* on call, propagate it to the ws service */
-static void server_on_call(struct afb_stub_ws *stubws, struct readbuf *rb)
-{
 	struct server_req *wreq;
-	char *cverb;
-	const char *uuid, *verb;
-	uint32_t flags, msgid;
-	size_t lenverb;
-	struct json_object *object;
 
 	afb_stub_ws_addref(stubws);
 
-	/* reads the call message data */
-	if (!readbuf_uint32(rb, &msgid)
-	 || !readbuf_uint32(rb, &flags)
-	 || !readbuf_string(rb, &verb, &lenverb)
-	 || !readbuf_string(rb, &uuid, NULL)
-	 || !readbuf_object(rb, &object))
-		goto overflow;
-
 	/* create the request */
-	wreq = malloc(++lenverb + sizeof *wreq);
+	wreq = malloc(sizeof *wreq);
 	if (wreq == NULL)
 		goto out_of_memory;
 
 	afb_xreq_init(&wreq->xreq, &server_req_xreq_itf);
 	wreq->stubws = stubws;
-	wreq->msgid = msgid;
-	cverb = (char*)&wreq[1];
-	memcpy(cverb, verb, lenverb);
+	wreq->call = call;
 
 	/* init the context */
-	if (afb_context_connect(&wreq->xreq.context, uuid, NULL) < 0)
+	if (afb_context_connect(&wreq->xreq.context, sessionid, NULL) < 0)
 		goto unconnected;
-	wreq->xreq.context.flags = flags;
 
 	/* makes the call */
 	wreq->xreq.cred = afb_cred_addref(stubws->cred);
 	wreq->xreq.api = stubws->apiname;
-	wreq->xreq.verb = cverb;
-	wreq->xreq.json = object;
+	wreq->xreq.verb = verb;
+	wreq->xreq.json = args;
 	afb_xreq_process(&wreq->xreq, stubws->apiset);
 	return;
 
 unconnected:
 	free(wreq);
 out_of_memory:
-	json_object_put(object);
-overflow:
+	json_object_put(args);
 	afb_stub_ws_unref(stubws);
+	afb_proto_ws_call_fail(call, "internal-error", NULL);
+	afb_proto_ws_call_unref(call);
 }
 
-/* on subcall reply */
-static void server_on_subcall_reply(struct afb_stub_ws *stubws, struct readbuf *rb)
-{
-	char ie;
-	uint32_t subcallid;
-	struct json_object *object;
-	struct server_subcall *sc, **psc;
-
-	/* reads the call message data */
-	if (!readbuf_uint32(rb, &subcallid)
-	 || !readbuf_char(rb, &ie)
-	 || !readbuf_object(rb, &object)) {
-		/* TODO bad protocol */
-		return;
-	}
-
-	/* search the subcall and unlink it */
-	pthread_mutex_lock(&stubws->mutex);
-	psc = &stubws->subcalls;
-	while ((sc = *psc) && sc->subcallid != subcallid)
-		psc = &sc->next;
-	if (!sc) {
-		pthread_mutex_unlock(&stubws->mutex);
-		/* TODO subcall not found */
-	} else {
-		*psc = sc->next;
-		pthread_mutex_unlock(&stubws->mutex);
-		sc->callback(sc->closure, -(int)ie, object);
-		free(sc);
-	}
-	json_object_put(object);
-}
-
-static void server_send_description(struct afb_stub_ws *stubws, uint32_t descid, struct json_object *descobj)
-{
-	struct writebuf wb = { .count = 0 };
-
-	if (!writebuf_char(&wb, CHAR_FOR_DESCRIPTION)
-	 || !writebuf_uint32(&wb, descid)
-	 || !writebuf_object(&wb, descobj)
-         || afb_ws_binary_v(stubws->ws, wb.iovec, wb.count) < 0)
-		ERROR("can't send description");
-}
-
-static void server_describe_job(int signum, void *closure)
+static void server_describe_sjob(int signum, void *closure)
 {
 	struct json_object *obj;
 	struct server_describe *desc = closure;
@@ -1093,130 +507,64 @@ static void server_describe_job(int signum, void *closure)
 	obj = !signum ? afb_apiset_describe(desc->stubws->apiset, desc->stubws->apiname) : NULL;
 
 	/* send it */
-	server_send_description(desc->stubws, desc->descid, obj);
+	afb_proto_ws_describe_put(desc->describe, obj);
 	json_object_put(obj);
 	afb_stub_ws_unref(desc->stubws);
-	free(desc);
-}
-
-/* on describe, propagate it to the ws service */
-static void server_on_describe(struct afb_stub_ws *stubws, struct readbuf *rb)
-{
-
-	uint32_t descid;
-	struct server_describe *desc;
-
-	/* reads the descid */
-	if (readbuf_uint32(rb, &descid)) {
-		/* create asynchronous job */
-		desc = malloc(sizeof *desc);
-		if (desc) {
-			desc->descid = descid;
-			desc->stubws = stubws;
-			afb_stub_ws_addref(stubws);
-			if (jobs_queue(NULL, 0, server_describe_job, desc) < 0)
-				server_describe_job(0, desc);
-			return;
-		}
-		server_send_description(stubws, descid, NULL);
-	}
-	ERROR("can't provide description");
-}
-
-/* callback when receiving binary data */
-static void server_on_binary(void *closure, char *data, size_t size)
-{
-	if (size > 0) {
-		struct readbuf rb = { .head = data, .end = data + size };
-		switch (*rb.head++) {
-		case CHAR_FOR_CALL:
-			server_on_call(closure, &rb);
-			break;
-		case CHAR_FOR_SUBCALL_REPLY:
-			server_on_subcall_reply(closure, &rb);
-			break;
-		case CHAR_FOR_DESCRIBE:
-			server_on_describe(closure, &rb);
-			break;
-		default: /* unexpected message */
-			/* TODO: close the connection */
-			break;
-		}
-	}
-	free(data);
 }
 
-/******************* server part: manage events **********************************/
-
-static void server_event_send(struct afb_stub_ws *stubws, char order, const char *event, int eventid, const char *data)
-{
-	int rc;
-	struct writebuf wb = { .count = 0 };
-
-	if (writebuf_char(&wb, order)
-	 && writebuf_uint32(&wb, eventid)
-	 && writebuf_string(&wb, event)
-	 && (data == NULL || writebuf_string(&wb, data))) {
-		rc = afb_ws_binary_v(stubws->ws, wb.iovec, wb.count);
-		if (rc >= 0)
-			return;
-	}
-	ERROR("error while sending %c for event %s", order, event);
-}
-
-static void server_event_add(void *closure, const char *event, int eventid)
-{
-	server_event_send(closure, CHAR_FOR_EVT_ADD, event, eventid, NULL);
-}
-
-static void server_event_remove(void *closure, const char *event, int eventid)
-{
-	server_event_send(closure, CHAR_FOR_EVT_DEL, event, eventid, NULL);
-}
-
-static void server_event_push(void *closure, const char *event, int eventid, struct json_object *object)
+static void server_describe_job(int signum, void *closure)
 {
-	const char *data = json_object_to_json_string_ext(object, JSON_C_TO_STRING_PLAIN);
-	server_event_send(closure, CHAR_FOR_EVT_PUSH, event, eventid, data ? : "null");
-	json_object_put(object);
+	server_describe_sjob(signum, closure);
+	free(closure);
 }
 
-static void server_event_broadcast(void *closure, const char *event, int eventid, struct json_object *object)
+static void on_describe(void *closure, struct afb_proto_ws_describe *describe)
 {
-	int rc;
+	struct server_describe *desc, sdesc;
 	struct afb_stub_ws *stubws = closure;
 
-	struct writebuf wb = { .count = 0 };
+	/* allocate (if possible) and init */
+	desc = malloc(sizeof *desc);
+	if (desc == NULL)
+		desc = &sdesc;
+	desc->stubws = stubws;
+	desc->describe = describe;
+	afb_stub_ws_addref(stubws);
 
-	if (writebuf_char(&wb, CHAR_FOR_EVT_BROADCAST) && writebuf_string(&wb, event) && writebuf_object(&wb, object)) {
-		rc = afb_ws_binary_v(stubws->ws, wb.iovec, wb.count);
-		if (rc < 0)
-			ERROR("error while broadcasting event %s", event);
-	} else
-		ERROR("error while broadcasting event %s", event);
-	json_object_put(object);
+	/* process */
+	if (desc == &sdesc)
+		jobs_call(NULL, 0, server_describe_sjob, desc);
+	else {
+		if (jobs_queue(NULL, 0, server_describe_job, desc) < 0)
+			jobs_call(NULL, 0, server_describe_job, desc);
+	}
 }
 
 /*****************************************************/
 
-/* callback when receiving a hangup */
-static void server_on_hangup(void *closure)
-{
-	struct afb_stub_ws *stubws = closure;
-
-	/* close the socket */
-	if (stubws->fd >= 0) {
-		close(stubws->fd);
-		stubws->fd = -1;
-		if (stubws->on_hangup)
-			stubws->on_hangup(stubws);
-	}
+static const struct afb_proto_ws_client_itf client_itf =
+{  
+	.on_reply_success = on_reply_success,
+	.on_reply_fail = on_reply_fail,
+	.on_event_create = on_event_create,
+	.on_event_remove = on_event_remove,
+	.on_event_subscribe = on_event_subscribe, 
+	.on_event_unsubscribe = on_event_unsubscribe,
+	.on_event_push = on_event_push,
+	.on_event_broadcast = on_event_broadcast,
+	.on_subcall = on_subcall
+};
 
-	/* release the client */
-	afb_stub_ws_unref(stubws);
-}
+static const struct afb_proto_ws_server_itf server_itf =
+{
+	.on_call = on_call,
+	.on_describe = on_describe
+};
 
-/*****************************************************/
+static struct afb_api_itf ws_api_itf = {
+	.call = client_call_cb,
+	.describe = client_describe_cb
+};
 
 /* the interface for events pushing */
 static const struct afb_evt_itf server_evt_itf = {
@@ -1226,32 +574,35 @@ static const struct afb_evt_itf server_evt_itf = {
 	.remove = server_event_remove
 };
 
-static const struct afb_ws_itf stub_ws_client_ws_itf =
+/*****************************************************/
+
+static void drop_all_events(struct afb_stub_ws *stubws)
 {
-	.on_close = NULL,
-	.on_text = NULL,
-	.on_binary = client_on_binary,
-	.on_error = NULL,
-	.on_hangup = NULL
-};
+	struct client_event *ev, *nxt;
+
+	ev = stubws->events;
+	stubws->events = NULL;
 
-static const struct afb_ws_itf server_ws_itf =
+	while (ev) {
+		nxt = ev->next;
+		afb_event_drop(ev->event);
+		free(ev);
+		ev = nxt;
+	}
+}
+
+/* callback when receiving a hangup */
+static void on_hangup(void *closure)
 {
-	.on_close = NULL,
-	.on_text = NULL,
-	.on_binary = server_on_binary,
-	.on_error = NULL,
-	.on_hangup = server_on_hangup
-};
+	struct afb_stub_ws *stubws = closure;
 
-static struct afb_api_itf ws_api_itf = {
-	.call = client_call_cb,
-	.describe = client_describe_cb
-};
+	if (stubws->on_hangup)
+		stubws->on_hangup(stubws);
+}
 
 /*****************************************************/
 
-static struct afb_stub_ws *afb_stub_ws_create(int fd, const char *apiname, struct afb_apiset *apiset, const struct afb_ws_itf *itf)
+static struct afb_stub_ws *afb_stub_ws_create(int fd, const char *apiname, struct afb_apiset *apiset, int client)
 {
 	struct afb_stub_ws *stubws;
 
@@ -1259,15 +610,15 @@ static struct afb_stub_ws *afb_stub_ws_create(int fd, const char *apiname, struc
 	if (stubws == NULL)
 		errno = ENOMEM;
 	else {
-		fcntl(fd, F_SETFD, FD_CLOEXEC);
-		fcntl(fd, F_SETFL, O_NONBLOCK);
-		stubws->ws = afb_ws_create(afb_common_get_event_loop(), fd, itf, stubws);
-		if (stubws->ws != NULL) {
-			stubws->fd = fd;
+		if (client)
+			stubws->proto = afb_proto_ws_create_client(fd, &client_itf, stubws);
+		else
+			stubws->proto = afb_proto_ws_create_server(fd, &server_itf, stubws);
+		if (stubws->proto != NULL) {
 			strcpy(stubws->apiname, apiname);
 			stubws->apiset = afb_apiset_addref(apiset);
 			stubws->refcount = 1;
-			stubws->subcalls = NULL;
+			afb_proto_ws_on_hangup(stubws->proto, on_hangup);
 			return stubws;
 		}
 		free(stubws);
@@ -1277,14 +628,14 @@ static struct afb_stub_ws *afb_stub_ws_create(int fd, const char *apiname, struc
 
 struct afb_stub_ws *afb_stub_ws_create_client(int fd, const char *apiname, struct afb_apiset *apiset)
 {
-	return afb_stub_ws_create(fd, apiname, apiset, &stub_ws_client_ws_itf);
+	return afb_stub_ws_create(fd, apiname, apiset, 1);
 }
 
 struct afb_stub_ws *afb_stub_ws_create_server(int fd, const char *apiname, struct afb_apiset *apiset)
 {
 	struct afb_stub_ws *stubws;
 
-	stubws = afb_stub_ws_create(fd, apiname, apiset, &server_ws_itf);
+	stubws = afb_stub_ws_create(fd, apiname, apiset, 0);
 	if (stubws) {
 		stubws->cred = afb_cred_create_for_socket(fd);
 		stubws->listener = afb_evt_listener_create(&server_evt_itf, stubws);
@@ -1297,18 +648,10 @@ struct afb_stub_ws *afb_stub_ws_create_server(int fd, const char *apiname, struc
 
 void afb_stub_ws_unref(struct afb_stub_ws *stubws)
 {
-	struct server_subcall *sc, *nsc;
-
 	if (!__atomic_sub_fetch(&stubws->refcount, 1, __ATOMIC_RELAXED)) {
+		drop_all_events(stubws);
 		afb_evt_listener_unref(stubws->listener);
-		afb_ws_destroy(stubws->ws);
-		nsc = stubws->subcalls;
-		while (nsc) {
-			sc= nsc;
-			nsc = sc->next;
-			sc->callback(sc->closure, 1, NULL);
-			free(sc);
-		}
+		afb_proto_ws_unref(stubws->proto);
 		afb_cred_unref(stubws->cred);
 		afb_apiset_unref(stubws->apiset);
 		free(stubws);
diff --git a/stress-server.sh b/stress-server.sh
index 09d06c44..643c8990 100755
--- a/stress-server.sh
+++ b/stress-server.sh
@@ -17,7 +17,7 @@ rm $OUT*
 case "$1" in
  --ws)
   shift
-  ARGS="-q --ldpaths=/tmp --binding=$HELLO --session-max=100 --ws-server=unix:@afw:hello --no-httpd --exec $AFB --session-max=100 --port=$PORT --ldpaths=/tmp --roothttp=$TEST --token=$TOKEN --ws-client=unix:@afw:hello "
+  ARGS="-q --no-ldpaths --binding=$HELLO --session-max=100 --ws-server=unix:@afw:hello --no-httpd --exec $AFB --session-max=100 --port=$PORT --no-ldpaths --roothttp=$TEST --token=$TOKEN --ws-client=unix:@afw:hello "
 #  ARGS="$ARGS -vvv --tracereq=all"
   ;;
  *)