Development talk:File API

Some quick questions to avoid forgetting them:

1) Will them be under the control of FileAPI (or, as they are now, fixed local storage)?

- dataroot/temp - dataroot/lang - dataroot/cache - dataroot/environment - dataroot/filter - dataroot/rss - dataroot/search - dataroot/sessions - dataroot/upgradelogs

Martin Dougiamas 03:20, 28 April 2008 (CDT) : I don't see these as being in the API - I've updated the spec.

2) Assuming we'll have a cool OOP FileAPI...

- a) Will it support different FileAPI classes (to be able to store in other systems) ? - b) Will it support multiple FileAPI classes working together (like the Repo) ?

Martin Dougiamas 03:20, 28 April 2008 (CDT) : Hmm, I suppose it makes sense to switch the backend from local file storage to specify something else (eg database storage) but multiple File storage places doesn't make sense to me, that is the Repository API and the Portfolio API.

3) I've annotated in red some things that have sounded strange in my first look.

Martin Dougiamas 03:20, 28 April 2008 (CDT) : Thanks, all fixed.

4) Are we going to have "directory records" in the implementation, or that is going to be handled exclusively by the "moodlepath" column?

Martin Dougiamas 03:20, 28 April 2008 (CDT) : Good point. I was thinking of moodlepath only but I wonder if directory records might be more efficient. New table, I guess.

5) One general question... are we going to "force" all modules to be "autocontained" ? How are we going to handle resources, for example (with all those css, links, images..). In general how are we going to handle multiple-file packages?

Martin Dougiamas 03:20, 28 April 2008 (CDT) : they'll be a set of files, probably in a "directory" specified by moodlepath of directory record. What problems do you see? Should we retain better knowledge of the original group of files?

That's all for now, ciao4niao :-) Eloy Lafuente (stronk7) 21:27, 5 April 2008 (CDT)

Making Storage 'content addressable'

One opportunity which this API opens up is the possibility of making the actual storage of files 'content addressable' . That is, if two users upload the same image for example, only store this file once on disk. This brings benefits in reducing the amount of storage and improving caching (especially in increasingly common situations the moodle data store served from a NFS directory or other remote storage similar). To do this we could use a hash like sha-1 on the file and store the file on disk named by its hash (rather than some arbitary id). Then when someone uploads the same file as has already been uploaded, the hash matches and we just point the database record to the same file on disk. This technique is increasingly being used by enterprise-style repositories as well as things like git. I can see the major benefits in things like scorm packages other such things which have 100's of small duplicate files stored multiple times per package and course, so sometimes you can have the same image file stored 20 different times across 20 different packages in one course, which is then duplicated for multiple classes etcetc. --Dan Poltawski 07:32, 1 June 2008 (CDT)

Specific File Attachments?

We have entries for 'moduleinstance', do we need entries to identify files per other attachments? Such as forum posts, wiki attachments, database attachments, assignment submissions? Mike Churchward 16:27, 9 June 2008 (CDT)