Fwd: Re: A common VFS and a Common conf-system [Part II]

[Kevin Krammer]

On Wednesday 09 March 2005 23:46, gtg990h at mail.gatech.edu wrote:

> Web browser gets a URI.
> It calls the equivalent of open() in the D-VFS API, and passes it the URI.
> The D-VFS library sends the open request to the D-VFS daemon.
> The D-VFS daemon checks to see if the parent is already mounted, and if
> not, has the kernel mount it using something like httpfs.

Who is going to unmount it and when?

> The D-VFS daemon calls open() on the resulting path, associating the D-VFS
> "file" object with the underlying fd.
> The D-VFS library uses whatever D-BUS protocol gets defined, and the D-VFS
> daemon implements those actions by reading/writing to the fd.

So the D-VFS using app would not use the POSIX file API?

> The nice thing about this approach is that if the user now wants to use a
> CLI app on the file, they can copy & paste the URI into their terminal, and
> it "Just Works".

I am afraid I don't understand how this would work.
Most likely any URI starts with the protocol name, thus a normal character.
Most CLI apps I know threat anything not starting with / as a relative path, a 
htttp:// URI would result in looking for a directory named http: relative to 
the CLI app's working directory.

> > I am not very experienced with the native API regarding non blocking IO.
> > Can an application open a file non-blocking and then use select/poll on
> > it without loosing quite some performance?
>
> It depends on the platform. BSD kqueues, Solars event ports, and Windows
> I/O completon ports, provide for high-performance notification of AIO
> transactons. I'd presume epoll would (or could) be able to do something
> similar.

My question was based on the assumption that you propose having all apps use 
the same (POSIX) API for access, in which case GUI apps would have to open 
all files non blocking but users would still expect local files to be very 
fast.

But from your other posts I understand that this was a wrong assumption, 
actually D-VFS aware apps would use a different access API than non aware 
ones.

Cheers,
Kevin