Initial description of the architecture

ARCHITECTURE.md

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+# Architecture of the container #
+
+Components
+============
+
+The container contains the following components :
+- An Ubuntu base system
+- The tini + supervisord startup and daemon control system
+- Nginx Web server
+- A backend ("novnc2") Python Web app providing an API (written with
+  Flask) on port 6079
+- A frontend VueJS Web app displayed to the user, which will wrap noVNC
+- noVNC + WebSockify providing the Web VNC client in an HTML5 canvas
+- Xvfb running the X11 server in memory
+- x11vnc exporting the X11 display through VNC
+- and all regular X applications, like the LXDE desktop and apps
+
+Wiring them all
+------------------
+
+Internally, Xvfb will be started in DISPLAY :1, then x11vnc will
+provide access to it on the default VNC port (5900).
+
+noVNC will be started listening to HTTP requests on port 6081.
+It is possible to connect directly to port 6081 of the container, to
+only use the regular noVNC Web interface (provided it is exported by
+the container).
+
+Above noVNC stands the VueJS frontend Web app provided by nginx, which
+will proxy the noVNC canvas, and will add some useful features over
+noVNC.
+
+User-oriented features
+==========================
+
+The Web frontend adds the following features :
+- upon display of the Web page, the app will detect the size of the
+  Web browser's window, and will invoke the backend API so as to make
+  sure the noVNC rendering ajusts to that size
+- provide a flash video rendering transporting the sound (???)
+