I made modifications to the code, in order to make the application a consumer of the central repository.
The modified version does this:
1) authenticates with Firefox accounts.
2) with these credentials, a request is sent to the server to retrieve the url of the user’s storage.
3) if the user has already written to the central repository, i.e. created a record with his/her storage url then the url received as a response from the central repository is the user’s url
4) if the user has no record on the central repository, the user will have to use a default server url provided.
Note: the permissions on the central repository are such that any user authenticated with Firefox accounts can write to the central repository, but, only the author of the record can read the record, for keeping the data (url) of the user safe.