File IO takeover - Virtual filesystem

Question

How can you create an empty file, and when any program reads from the file, the content shuld come from somewhere else. And when any program writes to the file the bytes to be written goes some where else then to the disk.
I have been looking at java.nio.. + FileChannel but I don't know if this would even be posible.
Just to get started I would like to have a simple program that "graps" on to an empty file, sending anything written to the file (by other programs) to the system output stream, and not to the empty file.
My ide would be something like this :
FileChannel cha = new RandomAccessFile("file","rw").getChannel();
// map/redirect cha to MyFileChannel
class MyFileChannel extends FileChannel {
// overwride methods in FileChannel
public ... write(...) {
System.out.println(...);
Would this be posible ? Have I misunderstood the FileChannel ?

Answer 1

It is importent to me that the solution is platform
indepentent : works on Linux( standard
Ubuntu/Fedora/Nowell - desktop instalation ),
Windows, Mac, Solaris.
This remote directory shuld be
accesable throu the local file system, so that you
can do all the stuff that you can do on real local
files .Stating it again - impossible. Doesn't even matter what language you use.
You are describing something that it fundamentally basic to an OS. There are probably OSes that doen't have a file system but you are unlikely to ever see one. Educational courses in Operating Systems always cover the file system.
A file system depends on the hardware of the system. A device that uses a flash rom is completely different than a system that uses a hard driver. But even systems that use hard drives use different hardware and assumptions about the data that is on the hardware.
If you look at the specification for C/C++ you will find that although IO operations are supported it is at the stream and random access level. There are no disk management interfaces in the specifications.
Each OS has a different API to access the file system. And specifics of that varies by OS.
Perhaps if you altered your requirements to the file level (not byte read level) then you can manage files. Even with java. You simply delete a old file and rename a file with new data to have the name of the old file. Then the next request gets the new data.
Can I somehow create a fake usb-disk and controll the IO ? Is it possible to do what you are asking (with no restrictions)? Yes. You would have to write a lot of software for each specific targeted system (and version specific as well.) You will need to use C/C++ and you will have to learn a LOT about the internals of each OS. You will need to learn a lot about C/C++ as well.
The solution will be very platform dependent. I would suspect that most of the code will specific to each target.