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From "Cedric NICOLAS" <>
Subject RE: Managing content in an SCXML file
Date Tue, 03 Nov 2009 23:32:06 GMT

Thanks for answer. Events for this state machine are quite simple, and I've
already fully implemented the communication layer. Events type being
triggered to the state machine will be : 
	- a first connexion from a device, 
	- a message from the device
	- an event from a master controller state machine.

The state machine in return can trigger events to :
	- the device that the SM is managing
	- the master controller state machine.

To be a little be more precise, there will be on server side on state
machine instance being created for each new device. Each of these instances
will control the corresponding device state, remotely, if you want. Then
there is a master state machine coordinating all devices children states
machines, as there is no direct communication between devices.

Objective is to have on the mobile device the lightest possible client
software, in order to be able to port easily that software on the different
mobile platforms, and also to have the full control as well of the business
logic but also of the UI on the server side, to be able to upgrade the UI on
the fly. The Scxml file will then fully define the behavior of the device,
but also the UI being displayed. The UI on mobile side is very very simple,
it is much lighter than HTML is. We will have one or two text fields and 3
buttons. It is why our markup language will be very simple as well : a tag
to fill the text field, and a tag to define button text and event.

My only concern here is how to embed easily in an scxml file this 2-tags
markup language for each state. This in order to have in only one state
machine file, as well the full business logic but the UI definition as well.
I don't want to have a separate resource file to handle the UI, in order to
have the scxml file defining and carrying all, it will be much easier to

All the other aspects of the project have already been solved.

-----Message d'origine-----
De : Martin Gainty [] 
Envoyé : mercredi 4 novembre 2009 00:10
À :
Objet : RE: Managing content in an SCXML file


a markup implies SGML..i assume this might be described as XSD or XML Schema
Can you describe the events this state-machine model would support?
can you describe the content each event would carry and or generate?
Can you describe what would be contained in the header for each Event?
Can you describe what the body would look like for each event?

You might be able to implement a simple listener that listens on fixed
host/port and when message is received (EOT is achieved after receiving
header and body)
you can hand the body of the message to device

can you confine the size of the message? 
if not you might want to implement a packet model to buffer the packets to a
known structure
(as in some sort of linked-list) 
until body EOT is achieved 

sounds like a fun project!
Bon Chance
Martin Gainty 
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> From:
> To:
> Subject: Managing content in an SCXML file
> Date: Tue, 3 Nov 2009 23:23:01 +0100
> Dear Rahul and others,
> I want to do a quite simple thing : having a state machine on a server
> controlling user interface of mobile clients. 
> The state machine would have a lot of states and complex stream, and for
> some specific states it will embedded a simple markup language content
> an html subset) that will be delivered to the mobile client which when it
> receives it, interpret and display it.
> For example the server state machine would have "connect" state that will
> triggered when the mobile is establishing a connection, and would react by
> giving to the mobile client the content to be displayed. An simple example
> would be :
> <state id="connect">
> 	<content>
> 		<title> Welcome ! </title>
> 		<button> text="Click here to continue" action ="send_OK"
> </button>
> 		<button> text="Quit" action ="send_Quit" </button>
> </content>
> 	<transition event="send_OK" target="next_state"/>
> 	<transition event="send_Quit" target="final_state"/>
> </state>
> In that case the content in <content> tags will be retrieved by the Java
> code on void connect() method, and sent to the device. Server will listen
> device and when receiving a message like send_OK, trigger this to the
> machine.
> To summarize I want to emulate a tiny web server hosting some tiny pages
> with a state machine.
> I've gone through all the documentation of Commons Scxml, and didn't find
> easy way to do this. The possible ways I see are to use a data model, but
> using <assign> tags for setting my content seems to be quite heavy to
> and don't know how to assign an XML tree to a data model node, and other
> possibility would be to use maybe custom actions, but how to describe in a
> simple way my XML like-content ?
> Do you have a suggestion to do this in an easy and readable way ?
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