[MUD-Dev] Matt's java problems....

[Adam]

On Fri, 26 Jul 2002, Matt Mihaly wrote:


> The bad news was that I should have listened to something
> Christopher Allen told me. He said they (Skotos) had investigated
> expanding a java client they have for more general use, but ran
> into a lot of problems with Java, and man was he right. We have
> been unable, for instance, to enable any sort of copying from the
> output window into a clipboard, and are also unable to log
> anything to the player's computer. This inability alone basically
> renders Java unsuitable for a full-featured text MUD client. (And
> while I'm not much of a programmer, if any of you clever
> programmers out there have figured out good work-arounds for this,
> I'd love to hear them.)

1. General important question: How are you running Java?

  From the context, it sounds like you're running Java applets
  inside a web-browser, rather than as java applications.

  This difference is critical, because Sun/Javasoft went out of
  their way to make applets "safe" and "secure by default" - to the
  extent of being unable to:
  
    - modify local files [ including preventing any local savefiles
    !!]
  
    - communicate with the internet [ except with the EXACT same
    server the applet was downloaded from ]
  
    - pretend to be an application [ "Warning: Applet window"
    appearing at the bottom of every applet window, so that you
    couldn't write an applet that looked like "Windows Login" or
    similar :) ]
  
  Fortunately, this wasn't just hacked together; Java has a
  comprehensive (although I haven't used it enough to vouch for its
  completeness) security-architecture, based upon being able to do
  things all the time without problems. In the background, every
  time a s security-questionable method call takes place, it is
  checked with the SecurityManager to see if it should go ahead. If
  so, fine, and the programmer probably doesn't even know it
  happened. If not, an Exception is thrown - but one which the
  programmer doesn't HAVE to handle, so it doesn't introduce
  unnecessary extra work if you're lazy :).
  
  SecurityManager's are mainly configured in practice by a textfile
  on the users machine.
  
  So, if there's something you can't do because of security reasons
  (IIRC, any user can override the restrictions on applets) then
  modifying their security settings file might solve things quickly.
  
  From the two problems you listed in particular, both of which are
  by default not-allowed for security reasons, I'm guessing this is
  your current main problem.
  
    (and aside from serious OS-imposed isssues (see 2. below), which
    are outside of sun's/java's control, I've never had any problems
    other than security with java clipboard operations, even having
    used them extensively)
  
2. Clipboard problems

  If that's not the case, I can only sympathise with your clipboard
  problems, and fear there may be nothing you can do. If you run
  into OS-clipboard problems, I think the only answer is: You're
  ****ed.

  It was only over the last 8 months when I switched to X11/linux
  for my fulltime desktop that I discovered that cut-copy-paste
  still doesn't "work" under X-Windows (FYI: [although since I'm
  sure several people on this list know/understand this better than
  me, corrections are welcome!] there are still [at least] 3
  competing standards [Old-X-Windows, KDE, Gnome? / New-X-Windows?] 
  for clipboard operations, and all are still extensively used by
  current applications. Mostly they cannot interact at all, or (in
  the case of the changes to X-Windows) they incompatibly use the
  same buffers. And different (recent) versions of KDE (IIRC 3.0
  compared to 2.x and >3.0) are incompatible with each other,
  causing further confusing amongst application-writers.

3. Workarounds

  Java Web Start has been going in the right direction to solve many
  of this type of "applet security too tight/too much effort for
  user to modify" - its an official Java extension/thingy,
  accessible from the main java.sun.com page under the products
  section.

Under win32, I've seen people "embed" java apps inside win32 apps
(IIRC using ActiveX or similar) so that the user didn't have to faff
about with installing java and / or running from the commandline.

AdamM


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