Possible changes for Attachments after TWikiReleaseSpring2001

Possible changes to AttachmentsUnderRevisionControl. If someone wants one of these I suggest the specific item is taken out to a new topic.

More efficient storing of binary deltas

Suggestion: you can look at the code I made in my fshar program: http://www-sop.inria.fr/koala/colas/fshar/
binary files are encoded in a special heuristic format that tries to confine binary differences into a small set of lines for easier diff. For instance, inserting a byte in the middle of a binary file will make the uuencoded files totally different, whereas with shar only some lines will be changed. Files are scanned before inclusion and will be encoded if found binary
I encourage you to steal my code to transparently incode and decode in this format to handle the binary file case. Look at the binary encoding at the end of the C file. It works quite well with documents formats (framemaker, word, powerpoint), saving space for revisions.
-- ColasNahaboo - 28 Mar 2001

Answer: Am I correct in thinking this would mean converting format before putting into RCS and unconverting on output? The idea being to save storage? If so, I think it would be better to leave this to the more general Store re-write as it will be quite a complex change. With re-write different mechanims could be used for storage, including this.
-- JohnTalintyre - 29-Mar-00

ColasNahaboo says he tested his algorithm with various Office formats and its space performance was actually worse than RCS in binary mode.

-- NicholasLee - 22 Apr 2001

Ability to delete an attachment DONE!

The attribute flag in the META:ATTACHMENT variable could have a "d" added for delete. The only difference to "h" (hidden) would be that the attachment would be removed from the pub directory. At present the move attachment can be used to move to a topic in the Trash Web.

• I've had a couple of requests for this -- MartinCleaver - 1 Nov 2001
• As of 01 Feb 2003 you can delete attachments by moving them to the trash topic. Select "attach" then click "action" for the attachment that you want to delete, then click "Move Attachment" then follow the instructions to move the attachment to the Trash.TrashAttachment topic. -- TobyCabot

-- JohnTalintyre - 20 Apr 2001

Ability to turn off storing attachments under revision control.

I think this should be fairly easy to do, but for now I'm not doing it. If there's demand then I'll do it.

-- JohnTalintyre - 24 Apr 2001

Labels so that users can have their own version numbers

This can be done by adding an extra paramater to META:FILEATTACHMENT. However, it might be better to have a more general solution that can work for topics and possibly groups of topics. e.g. put a label on all results of a search, so you can get back same set of topics (i.e. same versions) in the future.

Add exclusive locking as an option

Some thing many people are keen on, but hard to get right. My thought would be to use a .lock file for the attachment and for locking to work the same way as for topics, except users can override the time the lock lasts e.g. initially set to 1 day, allow user to increase to up to 1 week.

I'm proposing the deployment of TWiki at my company, and this came up as one of the big gotta-haves, since we do a lot of work in attachments (for delivery to customers, etc). My thought on this is that the "lock" should be advisory, i.e. it will stay in place until either the holder releases it or another user steals it. Then timeouts aren't a big issue. -- TobyCabot - 25 Jan 2004

I agree - this would be an incredibly useful feature. I'm in the same situation of proposing a TWiki deployment (as opposed to Microsoft SharePoint) but we really do need to have a locking system for our docs, it'll be hard to sell without it. Does anyone know if any progress been made on this issue? -- AnnaSmith - 16 Nov 2005

Security - read control for attachments

-- JohnTalintyre - 24 Apr 2001

There are many good ideas here.. and some are being discussed now...