Monitoring JVM Parameters

Hi All,
Is there a ways to monitor/change JVM parameters at runtime?
Example
If I pass a custom jvm parameter in the following way:
java -Dmy.custom.argument=myvalue -jar Stylepad.jarIs there a way to monitor this argument (-Dmy.custom.argument=myvalue) at runtime with both read and write permissions?
As far as I know the platform management mbeans only allows us to view such jvm parameters in read only mode (via java.lang.Runtime MBean).
Could any one help me to solve this problem?
Thanks in Advance!
Jini

Hi,
You could write your own MBean to do so.
However you should be careful about security: if your MBean allows to change just
any System property and isn't protected then you would be creating a security hole.
There's also a second consideration, which is that changing the value of a System
property at runtime might have no effect: it would mostly depends on how the code
that depends on that System property uses it.
Most applications will read their property only once, at initialization time. Changing
a property after such an application has performed its initialization phase has usually
no effect on that application.
On a pure conceptual/general level I would be tempted to qualify what you are
asking for as 'fragile' (best case) or 'dangerous' (worst case).
If however you still want to proceed in this direction you may be interested by this
blog entry:
http://weblogs.java.net/blog/emcmanus/archive/2006/11/a_real_example.html
It isn't exactly what you are asking for but it may help you on your way.
Hope this helps,
-- daniel
JMX, SNMP, Java, etc...
http://blogs.sun.com/jmxetc

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