Proxy Lingvodoc server

[vmonakhov]

The task is to have second instance of Lingvodoc server with small quantity of dictionaries in self copy of DataBase.
Copied dictionaries: their attributes (e.g. a titles), their components (e.g. files) should be synchronized with central DataBase instance. So we need to track any changes and to synchronize only the changed square: lexical entry, attribute or file. This synchronization should have some periodicity, may be interactive or will be manual.

Several points compose this task, they will be described apart:

1. Authentication and objects subscription
2. Synchronization of objects and files
3. DataBase mutations and consistency of the app
4. Synchronization periodicity
5. Port for synchronization and its security
6. Security of the app using Nuitka

[vmonakhov]

1. Authentication and objects subscription

Any object in Lingvodoc DataBase has client_id and object_id. They are generated automatically on logging in (client_id) and new object creation (dictionary, entry, entity and so on). So authentication means a NEW client_id for EXISTING user_id. Anytime we logging in to remote server we should get a generated client_id from the central one. So the remote user_id and client_id will be stored in central DataBase instance, and a new user can be added only there.

[vmonakhov]

2. Synchronization of objects and files

In 'objecttoc' table we should store changing time for every object in Database. So if on synchronization a remote timestamp is bigger than a central one - we synchronize such objects to central Database and/or file storage. On the contrary we will synchronize to another end. In the case of equal timestamps we don't synchronize anything. This mechanism is very perspective and should be implemented first. For transfer of files we can use gzip archiving and control sum algorithm.

As well we should implement 'Get my dictionaries' functionality on remote server and/or 'Share dictionary' on central one. So at first a user logging in remotely and have no any dictionary there but have own dictionaries on central server. Thus we should give an opportunity of sharing or getting own dictionaries. It seems like sharing is much easier and we start with it.

[vmonakhov]

3. Database mutation and consistency of the app

After Lingvodoc app changing and/or Database mutation we should apply the changes to the remote app and Database as well. So we can manually do this every time on changes. Or on next synchronization the remote app will compare app versions and Database revisions between the servers and say about any difference. Different revisions of Database must block any synchronization. Different versions of app don't block synchronization but should be indicated.

[vmonakhov]

4. Synchronization periodicity

Whereas revisions and/or versions from the previous point may be different, will be compared on synchronization and synchronization will take place not often, we will trigger it manually or by timer. I thing firstly it will be implemented as manual. Then if necessary we can implement a timer and/or interactive synchronization. But to be honest, the timer or interactivity can be needed by the customer not soon.

[vmonakhov]

5. Port for synchronization and its security

Remote and central Lingvodoc servers will be placed NOT in common local network, so they will communicate through the Internet. Synchronization of dictionaries requires a special open ports on the servers and using of suitable protocol (may be gRPC, but I'm not sure). Such port must have secure protection.

[vmonakhov]

6. Security of the app using Nuitka

If we are concerned with keeping our app in commercial or any other purpose, maybe we need to secure it using Nuitka. I already tried to do this, but this is a separate full task and, I afraid, this is not easily. Anyway this task is enough promising.