diff --git a/zig-impl/crystal/some-crystal-app/src/json.cr b/zig-impl/crystal/some-crystal-app/src/json.cr
index f0582f4..5bbfcaa 100644
--- a/zig-impl/crystal/some-crystal-app/src/json.cr
+++ b/zig-impl/crystal/some-crystal-app/src/json.cr
@@ -1,5 +1,14 @@
 require "json"
 
+# IPC::JSON is the mother class for all exchanged messages (using JSON).
+# IPC::JSON inherited classes have a common 'type' class attribute,
+# which enables to find the right IPC::JSON+ class given a TypedMessage's type.
+
+# All transfered messages are typed messages.
+# TypedMessage = u8 type (= IPC::JSON+ class type) + JSON content.
+# 'JSON content' being a serialized IPC::JSON+ class.
+
+# Conventionally, IPC::JSON+ classes have a 'handle' method to process incoming messages.
 class IPC::JSON
 	include ::JSON::Serializable
 
@@ -22,12 +31,18 @@ class IPC::JSON
 end
 
 class IPC
+	# Schedule messages contained into IPC::JSON+.
 	def schedule(fd : Int32, message : IPC::JSON)
-		schedule fd, message.type.to_u8, message.to_json
+		typed_msg = IPCMessage::TypedMessage.new message.type.to_u8, message.to_json
+		schedule fd, typed_msg
+	end
+	def write(fd : Int32, message : IPC::JSON)
+		typed_msg = IPCMessage::TypedMessage.new message.type.to_u8, message.to_json
+		write fd, typed_msg
 	end
 end
 
-# CAUTION: Only use this method on an Array(IPC::JSON.class)
+# CAUTION: only use this method on an Array(IPC::JSON.class).
 class Array(T)
 	def parse_ipc_json(message : IPCMessage::TypedMessage) : IPC::JSON?
 		message_type = find &.type.==(message.type)