How to monitor Memory BUS in of computer in Java?

[darksteel21]

Hi All,

I want to ask for an idea on how to monitor the memory bus of a computer (windows and sun solaris platform) using JAVA technology. Does JAVA has the capability or a library for this?

Thanks,
Mark

[Oralloy]

What are you trying to monitor?

Java, its self, is a virtual machine, completely hiding the underlieing system.

So, if you are going to do something with the lower level machine, you'll have to use JNI or JNA to drive "native" code, which in-turn interrogates the actual hardware.

Hope this helps.

Cheers!
Oralloy

[darksteel21]

I am trying to monitor a parallel port bus. Is there an available Java API/Library for this? what is JNA or JNI?
Do you have references on these?

Thanks,
Mark Tan

[horace1]

not sure what you mean by the "parallel port bus".
If you mean the PCs parallel port looks at the Java communications API
http://www.oracle.com/technetwork/ja...sp-141752.html
and
http://www.google.co.uk/url?sa=t&sou...3TDuzw&cad=rja

[darksteel21]

yeah...the PC's parallel ports..
i will try to study the links you provided...
Thanks!

[Oralloy]

Mark,

There are lots of libraries out there to use, if you look around.

JNA is Java Native Access
JNI is Java Native Interface

They are two different modules that interface with "native" code (.DLLs or .SOs).

Luck!
Oralloy

[darksteel21]

Oh i see.. i guess i have to research more...
thanks a lot!

[Oralloy]

Mark,

The links from horace1 are a starting point. unfortunately (and this is from my past, it may have changed) Sun dropped support of a port management class, because of the incompatabilities between platforms. Basically they were unable to build (and reasonably maintain) an I/O model that was consistent across platforms, as well as being useful.

So, you are out of luck as far as a Oracle/Sun supported package. Fortunately, there are a few shareware and commercial packages available. The trade-off is time spent versus cost of package. You have to make that call. A couple hundred dollars is cheap, compared to several days of your time.

Cheers!
Oralloy

[darksteel21]

Oralloy,

What shareware and commercial package would you recommend me? are these packages are for JAVA and good for any OS platforms?

Mark Tan

[Oralloy]

Mark,

As far as I know, none of the packages is particularly portable across O/S platforms.

This page will give you a general indication of the difficulties involved in Serial and Parallel I/O under Java.

The problem with "portable" packages is that most programmers are focused on one class of system or other. PC programmers are generally unconcerned with writing code for Linux systems, BEOS systems, or telephones.

So - what you need to do is understand your requirements - what platforms are you targeting with your application? What capabilities do you really need? What are you actually trying to accomplish?

Once you have your requirements, then you can start surveying the available packages. If you are lucky, there is a single package, which gives you everything you need on all systems. Unfortunately, I don't think you're going to find one for Serial-I/O or Parallel-I/O. If you can't find a single package, look for a set of packages that give you what you need on your various target platforms.

In the later case, you will have to write a meta-package that conditionally loads lower-level packages depending on the operating system it is running on. Essentially you will have to define your own abstract I/O system and then dispatch from it to the system you loaded.

Sorry I can't give you names of packages to solve your problems. I do not know what capabilities you need, or the systems you need your application to work on. However, THIS is a Yahoo search that might be a good starting point.

Good Luck!
Oralloy

[darksteel21]

oh..i see...
Thanks alot for sharing your ideas..

[horace1]

Portability across operating systems is certainly a problem. I have used the Java communications API on Windows platforms without any problems
http://www.oracle.com/technetwork/ja...sp-141752.html
Never tried it on Linux, tend to work in C or C++ then.
Can you tell us what you are trying to do with the parallel port? I gave up using serial or parallel ports to communicate with external devices some time back, now use USB, Bluetooth or TCP/IP over wired etherenet or WiFi

[darksteel21]

Thanks for that horace1, but here is my another question : is there a way on JAVA on making a data look up on PC's RAM?

[horace1]

don't know any way of doing this directly. Modern operating systems tend to stop programs looking outside their own address space and accessing hardware directly and Java is runningin its own virtual machine.
You could use the Java exec command
http://download.oracle.com/javase/1....g/Runtime.html
to run operating system programs to dump memory contents and by connecting streams to the program input and output send it commands and look at the output.