SimpleConfiguration and system properties

Hello,

I have a suggestion which I think could improve the current
jPOS-EE/QBean configuration scheme.

When I deploy a jPOS-EE application it usually goes through three
different environments: development, staging and production. With
the current configuration scheme this means that I have to modify
the QBean XML configuration files for each environment. I would
like to avoid this, and would prefer to have a single unix-style
configuration file on each environment instead. 

I recently came across the Jetty webserver and noticed how system
properties is used in jetty configuration files.

Snip from http://jetty.mortbay.org/jetty5/tut/Server.html

  <New class="org.mortbay.http.SocketListener">
    <Set name="Port">
      <SystemProperty name="jetty.port" default="8080"/>
    </Set>
  </New>

Using system properties this way I would be able to modify the
service wrapper to pass settings from a unix-style configuration
file to the java environment using java -Dsetting=value.

What do you think about this? I believe it would require only
minor changes to org.jpos.core.SimpleConfiguration.

best regards,
  Thomas

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