[[!meta title="Architecture"]]

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# Architecture overview

## Assumptions

The architecture has been designed under the following assumptions:

* Privacy is important, and should be the default. People should only
  have access to the information they are authorized to access.

* Members should be able to see their own information, without having
  to go through the Effi membership register admin.

* It's not practical to have every member have a password.
  Authentication can be done by sending the member a unique,
  single-use link when they want to log in.

## Components

[[!img arch.png]]

Effireg consists of four main components:

* **effiapi** provides a RESTful HTTP API for managing the membership
  data, and for doing things with or to the data. All operations on
  the data go via the API.

* **effiweb** provides the frontend for the web application to use the
  membership register. It renders HTML to the user, is accesses via a
  web browser, and generally is the user-visible part of Effireg.

  Everything effiweb does, it does by using the effiapi API. If any
  other user interfaces are added (say, mobile or command line), they
  will be parallel to effiweb and will also use the effiapi API in the
  same way as effiweb.

* **Qvisqve** provides authentication of end-users (the members, and
  admins). It lets users log in, and keeps track of what each user is
  allowed to do.

* **Muck-POC** stores the actual membership register data, and
  controls access to it, based on access tokens from Qvisqve.

## Authentication

[OpenID Connect]: https://openid.net/specs/openid-connect-core-1_0.html
[OAuth2]: https://oauth.net/2/

End-users are authenticated using the [OpenID Connect][] protocol,
specifically the authorization code flow. In this flow, Qvisqve
provides cryptographically signed access tokens, which identify the
user and specify a list of things the user may do. The signature
guarantees the token comes from Qvisqve.

Non-interactive API clients are authenticated using the [OAuth2][]
protocol, specifically using client credential grants. This also
provides an access token, similar to the one from end-user
authentication.

# Data model

The membership register stores data as "resources" in Muck-POC. Each
resource is a JSON object. The following types of objects are
supported:

* **subject** represents a person who is allowed to use the register;
  it it used to identify the user for authentication
* **password** stores the encrypted password for a subject
* **memb** represets a subject's membership in Effi

### Subject resource

A subject resource has the following fields:

* `username` — the username of the subject; this can change, the
  subject is identified by the resource identifier in the register,
  not by the username

The subject resource does not have any data that isn't needed for
end-user identification. Effiapi manages and Qvisqve uses the subject
resource.

### Password resource

A password resource has the following fields:

* `subject_id` — resource id of the subject whose password this
  is
* `version` — version of the password resource (identifies
  algorithm); must be 1
* `hash` — the password, encrypted with the scrypt algorithm
* `salt` — a random string to prevent dictionary attacks
* `key_len` — parameter for scrypt
* `N` — parameter for scrypt
* `r` — parameter for scrypt
* `p` — parameter for scrypt

Effiapi manages and Qvisqve uses the password resource.

### Member resource (memb)

A membership resource has the following fields:

* `subject-id` — the resource id of the subject resource for
  the member
* `fullname` — the full name of the member
* `primary-email` — the primary email address for the member
  (and currently the only one)
* `years-paid` — list of integers for the years for which the
  member has paid their membership

Effiapi manages and uses the memb resource. Effiweb renders it for the
user.