Re: [Openjnlp-devel] Handling System.err (and System.out)

[Christopher H. <he...@ez...>]

On Friday 14 June 2002 11:43 am, you wrote:
> On Thursday, June 6, 2002, at 12:46 AM, Christopher Heiny wrote:
> > I've noticed we tend to lose a lot of information written to System.err
> > (and
> > in some cases to System.out).  System.err is especially important, since
>
> Are messages really being lost? My testing shows all messages. On Mac OS
> X they go to the system console until the GUI comes up, and then into
> the Console window. If I run from the command line the messages show up
> in my terminal window.

The CLI interface works the same for Linux.  The GUI is another matter - the 
messages are lost until you open the OpenJNLP Console (they are not appearing 
on my system console under KDE - potentially this is my configuration, which 
is something to look into).



> > right now loading and/or applications can fail silently, leaving the
> > user (or
> > even the developer :-) ) to wonder what the heck happened, and probably
> > abandoning OpenJNLP abandoning for other solutions.
>
> This is a really tough problem to address, I've run into this before on
> other projects that launch Java apps. There is no way to tell if a Java
> app "fails" other than the obvious like not finding the main class. Once
> it starts running the class loader may fail to find a class but that
> doesn't necessarily mean the app failed.

True.  We're trying to address a similar issue with our .jnlp deployed 
applications here.  We don't have a complete solution, but it is important to 
minimize this problem's impact.  (see following)



[snip suggestion to redirect System.err to pop-up in GUI mode]
>
> I'd have to disagree with this. This would get annoying very quickly.
> The whole point of the console is to provide the capability to see
> diagnostic messages but in a non-obtrusive manner. It is impossible to
> tell which messages are "alert" messages and which are normal output by
> the app that's being run. Because the messages go into the console even
> when it's not visible, a user can always see what's happening or has
> happened.

Well, things written to System.err are by definition alerts and not normal 
output, right?  That's what System.err is for.  System.out is for normal 
output, and I'm suggesting no change in its handling.

My personal feeling is that any application that writes normal messages to 
System.err needs to have its head examined. :-)  If you're writing to 
System.err, it's because you want to call attention to something that has 
probably not gone as the user expected it to.

Under Linux, most users are unlikely to have a system console open.  This is 
even more likely under Solaris.  In the case of an app failing to launch (for 
example) under the current handling of System.err, this results a silent and 
mysterious failure.  This is a >big< user dissatisfier, and because OpenJNLP 
is the primary interface, it is receiving the blame (around here we're using 
OpenJNLP to deploy some of our internal tools, and of course people have 
discovered that there are other cool .jnlps out there on the internet, and 
when those don't work, it's not the application's fault...).


> Have you tried Java Web Start to see how it behaves? I've noticed that
> you can launch an app with its own console open which has its advantages
> but doesn't give the user a feeling of centralized management.

I'll try to characterize JWS's behavior.

					Chris