Re: Store some data when JVM is active

From:
"Andrew Thompson" <u32984@uwe>
Newsgroups:
comp.lang.java.programmer
Date:
Fri, 19 Oct 2007 12:20:05 GMT
Message-ID:
<79ec497a2c687@uwe>
tomas wrote:

It is possible to store some data (very samall amount) when JVM is
active (disable) in pc ? It is situation.. I run one java application
(Swing app) few minutes leater run another application (also Swing
app) and for example applet on this same pc this same JVM and I must
store some data which the firsrt and second app (Swing) and applet


Applets are run within a strict security sandbox unless
the code is digitally signed, and accepted by the user.
Even then, the paths that they can right/read form, might
be very limited (e.g. latest IE/Vista bug).

Do your end users really need an applet?

Applets can be launched using Java Web Start*, but
if you want something free floating, you might as
well use a (J)Frame.

JWS apps. also get a security sandbox, but the JNLP API
allows us to 'break out' of it (with user permission), to do
things like access files**.

Even better, JWS provides the 'muffin' (like a cookie, but
for web start) that allows us to share information across
different apps. from the same codebase ('site'). This is
in the PersistenceService***.

* <http://www.physci.org/jws/#jtest>
** <http://www.physci.org/jws/#fs>
*** <http://www.physci.org/jws/#ps>
(but perhaps Sun has a better example of sharing
the muffins *between* apps)
<http://java.sun.com/j2se/1.4.2/docs/guide/jws/developersguide/examples.html#PersistenceService

..can
read... I can`t use any database, file itc... So a looking for some
solution witch score data in JVM environment...


Don't store any information within the JRE
directories themselves.

...It is possible ?


Sure - web start is one way.

There are other ways for 'full permission' standard
desktop apps (Properties, Preferences..).

--
Andrew Thompson
http://www.athompson.info/andrew/

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