diff --git a/.gitignore b/.gitignore
index 352b3fe16..958457cad 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,6 +5,8 @@
 /tezos-webclient
 /tezos-attacker
 
+/src/.ocamlinit.utils
+/src/.ocamlinit.node
 /src/Makefile.local
 
 /src/webclient_static.ml
diff --git a/src/Makefile b/src/Makefile
index 7446a4d04..63da34e20 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -65,6 +65,8 @@ node/updater/proto_environment.cmi: \
 	@echo OCAMLOPT ${TARGET} $@
 	@$(OCAMLOPT) -nopervasives -nostdlib -opaque -I tmp -I node/updater -c $<
 
+node/updater/protocol.cmi: node/updater/protocol.cmx
+
 partial-clean::
 	rm -f node/updater/proto_environment.mli
 	rm -f node/updater/environment_gen
@@ -190,6 +192,7 @@ UTILS_PACKAGES := \
   calendar \
   ezjsonm \
   ipaddr.unix \
+  lwt.unix \
   mtime.os \
   nocrypto \
   sodium \
@@ -208,6 +211,12 @@ utils.cmxa: ${UTILS_LIB_IMPLS:.ml=.cmx}
 	@echo LINK $(notdir $@)
 	@${OCAMLOPT} ${OCAMLFLAGS} -a -o $@ $^
 
+utils.top: DEVFLAGS=
+utils.top:
+	( $(patsubst %, echo "#require \"%\";;" ; ,${UTILS_PACKAGES}) ) > .ocamlinit.utils
+	( $(patsubst %, echo "#mod_use \"%\";;" ; ,${MINUTILS_LIB_IMPLS} ${UTILS_LIB_IMPLS}) ) >> .ocamlinit.utils
+	utop -init .ocamlinit.utils ${OCAMLFLAGS}
+
 ############################################################################
 ## Node protocol compiler (also embedded in the main program)
 ############################################################################
@@ -280,7 +289,6 @@ NODE_LIB_INTFS := \
   node/db/store.mli \
   node/db/db_proxy.mli \
   \
-  node/updater/protocol.mli \
   node/updater/updater.mli \
   node/updater/proto_environment.mli \
   node/updater/register.mli \
@@ -319,6 +327,7 @@ NODE_LIB_IMPLS := \
   node/db/context.ml \
   node/db/db_proxy.ml \
   \
+  node/updater/protocol.ml \
   node/updater/updater.ml \
   node/updater/environment.ml \
   node/updater/proto_environment.ml \
@@ -390,6 +399,14 @@ ${TZNODE}: minutils.cmxa utils.cmxa compiler.cmxa node.cmxa ${EMBEDDED_NODE_PROT
 partial-clean::
 	-rm -f proto/*.cm* proto/*.a
 
+node.top: DEVFLAGS=
+node.top: ${MINUTILS_LIB_IMPLS} ${UTILS_LIB_IMPLS} ${COMPILER_LIB_IMPLS} ${NODE_LIB_IMPLS}
+	( $(patsubst %, echo "#require \"%\";;" ; ,${NODE_PACKAGES}) ) > .ocamlinit.node
+	( $(patsubst %, echo "#mod_use \"%\";;" ; ,${MINUTILS_LIB_IMPLS} ${UTILS_LIB_IMPLS}) ) >> .ocamlinit.node
+	( $(patsubst %, echo "open %;;" ; ,Error_monad Hash Utils) ) >> .ocamlinit.node
+	( $(patsubst %, echo "#mod_use \"%\";;" ; ,${COMPILER_LIB_IMPLS} ${NODE_LIB_IMPLS}) ) >> .ocamlinit.node
+	utop -init .ocamlinit.node ${OCAMLFLAGS}
+
 ## Embedded protocol modules
 
 .SECONDEXPANSION:
diff --git a/src/node/updater/protocol.mli b/src/node/updater/protocol.ml
similarity index 100%
rename from src/node/updater/protocol.mli
rename to src/node/updater/protocol.ml
diff --git a/src/utils/logging.ml b/src/utils/logging.ml
index 0eb2088b9..fd4674057 100644
--- a/src/utils/logging.ml
+++ b/src/utils/logging.ml
@@ -95,6 +95,7 @@ type template = Lwt_log.template
 let default_template = "$(date) - $(section): $(message)"
 
 module Output = struct
+
   type t =
     | Null
     | Stdout
@@ -102,69 +103,70 @@ module Output = struct
     | File of string
     | Syslog of Lwt_log.syslog_facility
 
+  let to_string : t -> string = function
+    | Null -> "/dev/null"
+    | Stdout -> "stdout"
+    | Stderr -> "stderr"
+    | File fp -> fp
+    | Syslog `Auth -> "syslog:auth"
+    | Syslog `Authpriv -> "syslog:authpriv"
+    | Syslog `Cron -> "syslog:cron"
+    | Syslog `Daemon -> "syslog:daemon"
+    | Syslog `FTP -> "syslog:ftp"
+    | Syslog `Kernel -> "syslog:kernel"
+    | Syslog `Local0 -> "syslog:local0"
+    | Syslog `Local1 -> "syslog:local1"
+    | Syslog `Local2 -> "syslog:local2"
+    | Syslog `Local3 -> "syslog:local3"
+    | Syslog `Local4 -> "syslog:local4"
+    | Syslog `Local5 -> "syslog:local5"
+    | Syslog `Local6 -> "syslog:local6"
+    | Syslog `Local7 -> "syslog:local7"
+    | Syslog `LPR -> "syslog:lpr"
+    | Syslog `Mail -> "syslog:mail"
+    | Syslog `News -> "syslog:news"
+    | Syslog `Syslog -> "syslog:syslog"
+    | Syslog `User -> "syslog:user"
+    | Syslog `UUCP -> "syslog:uucp"
+    | Syslog `NTP -> "syslog:ntp"
+    | Syslog `Security -> "syslog:security"
+    | Syslog `Console -> "syslog:console"
+
+  let of_string : string -> t = function
+    | "/dev/null" | "null" -> Null
+    | "stdout" -> Stdout
+    | "stderr" -> Stderr
+    | "syslog:auth" -> Syslog `Auth
+    | "syslog:authpriv" -> Syslog `Authpriv
+    | "syslog:cron" -> Syslog `Cron
+    | "syslog:daemon" -> Syslog `Daemon
+    | "syslog:ftp" -> Syslog `FTP
+    | "syslog:kernel" -> Syslog `Kernel
+    | "syslog:local0" -> Syslog `Local0
+    | "syslog:local1" -> Syslog `Local1
+    | "syslog:local2" -> Syslog `Local2
+    | "syslog:local3" -> Syslog `Local3
+    | "syslog:local4" -> Syslog `Local4
+    | "syslog:local5" -> Syslog `Local5
+    | "syslog:local6" -> Syslog `Local6
+    | "syslog:local7" -> Syslog `Local7
+    | "syslog:lpr" -> Syslog `LPR
+    | "syslog:mail" -> Syslog `Mail
+    | "syslog:news" -> Syslog `News
+    | "syslog:syslog" -> Syslog `Syslog
+    | "syslog:user" -> Syslog `User
+    | "syslog:uucp" -> Syslog `UUCP
+    | "syslog:ntp" -> Syslog `NTP
+    | "syslog:security" -> Syslog `Security
+    | "syslog:console" -> Syslog `Console
+    (* | s when start_with "syslog:" FIXME error or warning. *)
+    | fp ->
+        (* TODO check absolute path *)
+        File fp
+
   let encoding =
     let open Data_encoding in
-    conv
-      (function
-        | Null -> "/dev/null"
-        | Stdout -> "stdout"
-        | Stderr -> "stderr"
-        | File fp -> fp
-        | Syslog `Auth -> "syslog:auth"
-        | Syslog `Authpriv -> "syslog:authpriv"
-        | Syslog `Cron -> "syslog:cron"
-        | Syslog `Daemon -> "syslog:daemon"
-        | Syslog `FTP -> "syslog:ftp"
-        | Syslog `Kernel -> "syslog:kernel"
-        | Syslog `Local0 -> "syslog:local0"
-        | Syslog `Local1 -> "syslog:local1"
-        | Syslog `Local2 -> "syslog:local2"
-        | Syslog `Local3 -> "syslog:local3"
-        | Syslog `Local4 -> "syslog:local4"
-        | Syslog `Local5 -> "syslog:local5"
-        | Syslog `Local6 -> "syslog:local6"
-        | Syslog `Local7 -> "syslog:local7"
-        | Syslog `LPR -> "syslog:lpr"
-        | Syslog `Mail -> "syslog:mail"
-        | Syslog `News -> "syslog:news"
-        | Syslog `Syslog -> "syslog:syslog"
-        | Syslog `User -> "syslog:user"
-        | Syslog `UUCP -> "syslog:uucp"
-        | Syslog `NTP -> "syslog:ntp"
-        | Syslog `Security -> "syslog:security"
-        | Syslog `Console -> "syslog:console")
-      (function
-        | "/dev/null" | "null" -> Null
-        | "stdout" -> Stdout
-        | "stderr" -> Stderr
-        | "syslog:auth" -> Syslog `Auth
-        | "syslog:authpriv" -> Syslog `Authpriv
-        | "syslog:cron" -> Syslog `Cron
-        | "syslog:daemon" -> Syslog `Daemon
-        | "syslog:ftp" -> Syslog `FTP
-        | "syslog:kernel" -> Syslog `Kernel
-        | "syslog:local0" -> Syslog `Local0
-        | "syslog:local1" -> Syslog `Local1
-        | "syslog:local2" -> Syslog `Local2
-        | "syslog:local3" -> Syslog `Local3
-        | "syslog:local4" -> Syslog `Local4
-        | "syslog:local5" -> Syslog `Local5
-        | "syslog:local6" -> Syslog `Local6
-        | "syslog:local7" -> Syslog `Local7
-        | "syslog:lpr" -> Syslog `LPR
-        | "syslog:mail" -> Syslog `Mail
-        | "syslog:news" -> Syslog `News
-        | "syslog:syslog" -> Syslog `Syslog
-        | "syslog:user" -> Syslog `User
-        | "syslog:uucp" -> Syslog `UUCP
-        | "syslog:ntp" -> Syslog `NTP
-        | "syslog:security" -> Syslog `Security
-        | "syslog:console" -> Syslog `Console
-        (* | s when start_with "syslog:" FIXME error or warning. *)
-        | fp ->
-            (* TODO check absolute path *)
-            File fp)
-      string
+    conv to_string of_string string
 
   let of_string str =
     try