You are viewing a plain text version of this content. The canonical link for it is here.
Posted to user@commons.apache.org by Miroslav Pokorny <mi...@gmail.com> on 2011/07/20 06:31:01 UTC
[vfs]
Hiho
I was just playing with Apache Commons VFS (thanks guys) and noticed that
>Ftp FileSystem< does not support random access writing as confirmed by
examining the capabilities.
[LIST_CHILDREN, URI, GET_LAST_MODIFIED, RENAME, APPEND_CONTENT, DELETE,
GET_TYPE, RANDOM_ACCESS_READ, READ_CONTENT, WRITE_CONTENT, CREATE]
It does however support random accesss reading and im just wondering is
there a particular reason why writing is not supported ?
tya
mP
RE: [vfs]
Posted by Gary Gregory <GG...@seagullsoftware.com>.
Hi Miroslav,
I think the best way to proceed is for you to create a JIRA and attach your code and unit tests.
Thank you for sharing! :)
Gary
-----Original Message-----
From: Miroslav Pokorny [mailto:miroslav.pokorny@gmail.com]
Sent: Wednesday, July 20, 2011 20:31 PM
To: Commons Users List
Subject: Re: [vfs]
Hi Gary,
While it is true that FTP is typically thought of as a streaming rather than random access file system, VFS does support random access reading. This is confirmed of course by the list of capabilities and code. I have a hacked version which supports random writing and does so using the following strategy.
- all read
- if outputstream present flush and closeand clear
- continue with reading byte(s)
- seek
- if outputstream present flush and closeand clear
- perform seek.
- // input and output streams are clear(nulled) and will be recreated
by the next read / write
- write methods
- if outputstream is absent connect to server and restart at file
pointer position
- write byte(s).
While it appears to work, i thought there might have been some deeper reasoning behinid the lack of inbuilt support in FtpFileProvider. After all that the same strategy is used for reading as i have described for writing.
My code is however a mess as i have only implemented writing for some RandomAccessContent.
If anyone is interested id be happy to share.
On Jul 20, 2011, at 0:45, "Miroslav Pokorny" <mi...@gmail.com>
> wrote:
>
> > Hiho
> >
> > I was just playing with Apache Commons VFS (thanks guys) and noticed
> > that
> >> Ftp FileSystem< does not support random access writing as confirmed
> >> by
> > examining the capabilities.
> >
> > [LIST_CHILDREN, URI, GET_LAST_MODIFIED, RENAME, APPEND_CONTENT,
> > DELETE, GET_TYPE, RANDOM_ACCESS_READ, READ_CONTENT, WRITE_CONTENT,
> > CREATE]
> >
> > It does however support random accesss reading and im just wondering
> > is there a particular reason why writing is not supported ?
> >
>
> Hello,
>
> The reason is probably as simple as the protocol is not a natural
> match for the feature. With FTP you stream the whole file up or down,
> not a random piece.
>
> Gary
>
> > tya
> >
> > mP
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: user-unsubscribe@commons.apache.org
> For additional commands, e-mail: user-help@commons.apache.org
>
>
--
mP
---------------------------------------------------------------------
To unsubscribe, e-mail: user-unsubscribe@commons.apache.org
For additional commands, e-mail: user-help@commons.apache.org
Re: [vfs]
Posted by Miroslav Pokorny <mi...@gmail.com>.
Hi Gary,
While it is true that FTP is typically thought of as a streaming rather than
random access file system, VFS does support random access reading. This is
confirmed of course by the list of capabilities and code. I have a hacked
version which supports random writing and does so using the following
strategy.
- all read
- if outputstream present flush and closeand clear
- continue with reading byte(s)
- seek
- if outputstream present flush and closeand clear
- perform seek.
- // input and output streams are clear(nulled) and will be recreated
by the next read / write
- write methods
- if outputstream is absent connect to server and restart at file
pointer position
- write byte(s).
While it appears to work, i thought there might have been some deeper
reasoning behinid the lack of inbuilt support in FtpFileProvider. After all
that the same strategy is used for reading as i have described for writing.
My code is however a mess as i have only implemented writing for some
RandomAccessContent.
If anyone is interested id be happy to share.
On Jul 20, 2011, at 0:45, "Miroslav Pokorny" <mi...@gmail.com>
> wrote:
>
> > Hiho
> >
> > I was just playing with Apache Commons VFS (thanks guys) and noticed that
> >> Ftp FileSystem< does not support random access writing as confirmed by
> > examining the capabilities.
> >
> > [LIST_CHILDREN, URI, GET_LAST_MODIFIED, RENAME, APPEND_CONTENT, DELETE,
> > GET_TYPE, RANDOM_ACCESS_READ, READ_CONTENT, WRITE_CONTENT, CREATE]
> >
> > It does however support random accesss reading and im just wondering is
> > there a particular reason why writing is not supported ?
> >
>
> Hello,
>
> The reason is probably as simple as the protocol is not a natural match for
> the feature. With FTP you stream the whole file up or down, not a random
> piece.
>
> Gary
>
> > tya
> >
> > mP
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: user-unsubscribe@commons.apache.org
> For additional commands, e-mail: user-help@commons.apache.org
>
>
--
mP
Re: [vfs]
Posted by Gary Gregory <GG...@seagullsoftware.com>.
On Jul 20, 2011, at 0:45, "Miroslav Pokorny" <mi...@gmail.com> wrote:
> Hiho
>
> I was just playing with Apache Commons VFS (thanks guys) and noticed that
>> Ftp FileSystem< does not support random access writing as confirmed by
> examining the capabilities.
>
> [LIST_CHILDREN, URI, GET_LAST_MODIFIED, RENAME, APPEND_CONTENT, DELETE,
> GET_TYPE, RANDOM_ACCESS_READ, READ_CONTENT, WRITE_CONTENT, CREATE]
>
> It does however support random accesss reading and im just wondering is
> there a particular reason why writing is not supported ?
>
Hello,
The reason is probably as simple as the protocol is not a natural match for the feature. With FTP you stream the whole file up or down, not a random piece.
Gary
> tya
>
> mP
---------------------------------------------------------------------
To unsubscribe, e-mail: user-unsubscribe@commons.apache.org
For additional commands, e-mail: user-help@commons.apache.org