Patrick Luby <[EMAIL PROTECTED]> wrote:
> Pier,
>
> I took a quick look at the code and found the RegisterNative function. This
> looks like an interesting feature. I also found the same function in your
> daemons code. The picture is becoming much clearer.
Well, RegisterNative is there since at least 4 years... Kinda hard to do
some callbacks without it....
> Let me try to get it working in the next few days with the callback function
> set
> to invoke setuid() and have the callback invoke (via Java reflection since it
> won't be there on Windows or standalone start.
IMO, it's a waste of time... You shouldn't call setuid from Java, but the
native code launching the VM should call appropriate methods at appropriate
moments of the lifecycle... As I said before:
1) CreateJavaVM
2) call Tomcat->initialize() (bind to ports)
3) set uid/euid/gid/egid/groups
4) call Tomcat->start() (accept connections)
5) wait for signal
6) call Tomcat->stop()
7) exit process...
All the code is already in place... Just need to be tied together...
> If I can get this to work, I will post the patches first so that all can
> inspect. Now that I understand this approach, it basically seems to work
> through
> the same logical steps (from a Tomcat Java code) perspective as invoking the
> callback function via JNI.
RegisterNative _is_ JNI... JNI is developed on two layers, call C from Java
(maybe using System.loadLibrary()), and that's what everyone knows.
Call Java from C (a little bit less known, but way more powerful)...
We need a JVM invocation API, not a Java callback mechanism, IMO...
> In your approach, the function is preloaded for Java (no System.loadLibrary()
> required) and the Java code invokes the function like any other method (it
> just happens that the method doesn't exist at compile time but only at
> runtime).
That's the beauty of JNI, you can do things that you won't even believe they
exist, like "compiling" (loading) a class when NOT all its methods are
there... It's the beauty of a Class seen as an Instance of an object (and
IMO the biggest advantage over things like SmallTalk)... JG thought it out
good...
Pier
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