[messaging] Zero-metadata object store

[Mikalai Birukou]

Peter,
>> Do metadata objects contain file tree information?
>>
>> Is file tree continuously packed into mobjects, i.e. many folders' data is placed into every mobject? Or, is it a one mobject per folder structure?
>>
> File system information and keying information are in mobjects, and they are continuously packed. The aim is to sync the repo index independently from any other content using as little bandwidth as possible.

Question about dobjects, objects with data chunks. Does dobject carry 
chunks from one file, or, can it have chunks from different files?

I am trying to picture it. If mobjects and dobjects carry data from 
different files, then will it be correct to think about zerostash like 
they are disk segments? Disk segments are always same size, and they may 
keep data from different files. Is disk analogy correct?

Longer question with context:

We have the following scenario for sync-ed fs. User has two devices, and 
some program runs on both of them. This program may be changing same 
files. Server is used to setup transaction walls on objects using object 
ids.

{ So far we use model with file stored in 1 or more objects, and not 
many files in same object. 
https://github.com/3nsoft/xsp-files#xsp-file-format provides packing 
bytes without knowledge of a file system. File system is formulated 
inside of a client project, with the following interface 
https://github.com/3nsoft/core-platform-electron/blob/master/src/api-defs/web3n.d.ts#L151 
. Each object changes in a transaction allowing for a strict version 
changes. Server api has transaction-related replies like in 
https://github.com/3nsoft/spec-server/blob/master/src/lib-common/service-api/3nstorage/owner.ts#L205 
}

Is it possible to have a similar transaction identification and change 
signalling using info available on the server (e.g. object ids), so that 
client with knowledge of mapping between this info and files can 
identify file system events, and be aware of current writes to server?