I wrote to the fuse mailing list, about the eifs/fmfs/mobifs. I am still not sure which name fits better, for simplicity I will refer to it as mobifs. Based on the feedback from the mailing list, it became clear for me, that mobifs can be implemented with help of fuse. However implementing it in kernel will avoid double context switch, copying buffers, etc. One of the powerful features of fuse is that you may develop proof of concepts for any kind of filesystem, and the if performance is an issue, recode a part to fit into the kernel. The user space solution for mobifs will be straightforward to implement, at a later stage a kernel module may come into being.
As summary, the goal of mobifs (everything is filesystem) is to allow transparent (read/write) access to the tree structure of files that have such a tree structure under the form of traditional directory tree structure and to present the leaves in form of text, that can be edited without compromising the format expected by the original tools that handle these files.
The driving motivation behind is also to avoid to learn hundreds of command line parameters of hundreds of tools that access such files and to be able to access the data that hides behind with traditional viewers, editors or other tools.
For example an sqllite database file has such a directory structure. instead of issuing sql statements, one would be able to acces such a file like:
#>vi blogs.sqllite@sqllite/tables/blogs/rows/by/uniqueid/mobifs-eifs-story/content
in this example “blogs” is the table containing the blog entries, “by” means that I want to access data by column name, “mobifs-eifs-story” is the unique id of the blog entry, and “content” is the field containing the content.
if your blog database would be on a mysql database on a remote server, you would do sthg. similar:
#>vi blogs.db.id@mysql/tables/blogs/wors/by/uniqueid/mobifs-eifs-story/content
in this case blogs.db.id would contain necessary info how to access the database (server ip, db name, username, password)
I am also not sure if there is sthg. like that out there, but based on my 15 years of linux experience I never met sthg. like what I would like to talk about.