WORA help required

Peter Murray-Rust peter at ursus.demon.co.uk
Sat Nov 29 15:31:28 GMT 1997

I am having a number or problems turning JUMBO into a WORA-compliant animal
(WriteOnceReadAnywhere). At present it is WUTROMIL
WriteUmpteenTimesReadOnMostIfLucky. Although some of the questions below
are not strictly XML-DEV specific, I think they are ones that other Java
XML hackers may encounter.  If you are a java expert and think the answer
is trivial, please mail me directly, else post to this list. [I suggest we
do not get into a discussion of the merits or otherwise of WORA.]

[An example of the sort of problem is that the latest JUMBO has decided
that local files throw a SecurityException 
'Codebase 'C:\cdrom\demos\' does not include scene1.sgm 
(even though the file is there ;-)] I haven't changed the browser (NS4.0)
nor the files, but it's just stopped working. This is why there is no
release of JUMBO for SGML/XML 97 (it works, but I can't release it on CDROM).

JUMBO is both an applet and a standalone application. It therefore has to
fit into the following matrix:

	java	jview	appletviewer	NS3.0	NS4.0	MSIE3	MSIE4	hotjava
W95	+	+	+		+	+	+	?	?
Mac	?		?		+	+	+	?
UNIX	+		+		+	+	+	?

This is 20 different environments (I have left blank the places where I
don't think there is an offering, and ? for where I haven't tried it. '+'
means that it has worked in the past when the phase of the moon was right.

Specific problems I would be very grateful for information are given below.
If there is a WWW site that deals with some of these I'd be grateful for
URLs. :

A JDK1.02/JDK1.1.x
	I have refrained from converting to 1.1. since I have been told that not
all browsers supported it. Is this still true? Or should I convert now?

B Applet/Application. 
B.1 Is there a function I can call to tell whether I am in an applet or
application? (At present I set a static variable  in main() or init() but
seems horrible. I tried doing things that would throw SecurityExceptions,
but this didn't seem reliable

B.2 I use ancillary files located in the *.class directories (e.g
icon.gif). A nice extension in JUMBO is a per-class schema.xml file, with
additional class information. Since CLASSPATH may contain many components,
how can I tell which component was used for the class I am now running, so
I can locate these files?

C javac/jvc

	I have problems compiling Lark V097 under javac. It throws a compiler
error trying to load Lark.class. (java.io.UTFDataFormatException). This
suggest that Lark which may have been compiled with jvc (Tim?) will not
load with javac. (I does *run* with java) I won't post all 28 layers of the
Stack Trace here but it starts at 
sun.tools.javac.Main.main(main.java:289) and continues to:
java.io.DataInputStream.readUTF(line 326)

I was running on W95. I have not tested this on UNIX.

D java/jview
	There are significant differences here, especially with filenames/URLs.
There are so many variant errors that I cannot reproduce them in detail.
They include:
	inconsistency with '\' and '/'
	non elision of '..' in java.net.URL newURL(URL context, String spec)
		(i.e. the resultant URL may have '../' in the middle; also if
		context corresponds to "." it seems to be ignored (I think this 		is
java, not jview)
Tim Bray posted me one 'fix' from James Clark which included testing for
the occurrence of '\'. I have had to do something similar, so the area
seems horrible and not very WORA. Is there a set of known kludges out there
rather than having to discover these at midnight? Is the problem compiler
dependent? version dependent? interpreter dependent? browser dependent? OS
dependent? or is it WORN WriteOnceRunNowhere? 


BTW anyone who would actually like to help sort this out in JUMBO ...? :-)
Peter Murray-Rust, Director Virtual School of Molecular Sciences, domestic
net connection
VSMS http://www.nottingham.ac.uk/vsms, Virtual Hyperglossary

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