source: main/eko-disco-specs/trunk/data.rst @ 10739

.. |n0| replace:: n\ :sub:`0`
.. |m0| replace:: m\ :sub:`0`

.. _label-data-entities:

Data Entities
=============

These are the data entities the new system is supposed to model. Each
of these entities should be addable, editable, and removable as
covered in more detail in :ref:`label-use-cases`.

For each entity we give a short description to tell what it means,
what its purpose is and in what regards (and how) it should be handled
by the system. Again the more detailed actions on these entities
provided by the system are described in the :ref:`label-use-cases`
section.

The data entities are sorted alphabetically, not by importance or
similar. Used description terms should link to other respective
entities/terms where possible.

Each data entitiy description provides a list of use cases and other
data entities connected. Connections to other data entities contain a
relationship telling how many instances of the described entity are
connected to how many instances of the related entity [#]_.


.. _label-contact-address:

Contact Address
---------------

A postal address.

Connected to: :ref:`label-contact-data` (n:1)

Used in the following use cases:


.. _label-contact-data:

Contact Data
------------

The data neccessary to contact some :ref:`label-customer`, staff
person or similar entity. Contact data might contain several
addresses, phone numbers, emails, etc.

Connected to: :ref:`label-customer` (1:1),
:ref:`label-contact-address` (1:|n0|), :ref:`label-contact-email`
(1:|n0|), :ref:`label-contact-phone` (1:|n0|)

Used in the following use cases:


.. _label-contact-email:

Contact Email
-------------

An email address with optional additional clear name. For email
addresses we store some timestamp that indicates when the respective
email address was last checked successfully (thus marking it a 'valid'
one).

Connected to: :ref:`label-contact-data` (|n0|:1),
:ref:`label-timestamp` (1:|m0|).

Used in the following use cases:


.. _label-contact-phone:

Contact Phone
-------------

Mobile phone number which is capable of receiving sms text messages.

Connected to: :ref:`label-contact-data` (|n0|:1)

Used in the following use cases:


.. _label-contract:

Contract
--------

A contract is created whenever a :ref:`label-customer` orders some
:ref:`label-service` from the system. It is always connected to a
:ref:`label-customer` and a :ref:`label-service` .

A contract is not necessarily written on paper and signed by
people. Instead it is an abstraction used inside the system.

It is always created from a :ref:`label-service` , which tells about
the basic data, with additional parameters set that depend on the type
of :ref:`label-service` ordered.

Contracts can trigger :ref:`label-transaction`\ s. For instance if some
:ref:`label-customer` orders a service. When the service charges
become due, a respective :ref:`label-transaction` is triggered.

Contracts can have multiple :ref:`label-contract-addon`.

Connected to: :ref:`label-service` (|n0|:1), :ref:`label-customer` (|n0|:1),
:ref:`label-contract-addon` (1:|n0|), :ref:`label-transaction` (|n0|, |m0|)

Used in the following use cases:


.. _label-contract-addon:

Contract Addon
--------------

Kind of 'sub contract' that always belongs to some already existing
:ref:`label-contract` but comes with an own set of
parameters. Contract addons are created by :ref:`label-contract`\ s.

Connected to: :ref:`label-contract` (|n0|:1)


.. _label-customer:

Customer
--------

Beneficiary of one or more :ref:`label-contract`\ s.

Customers are added to the system by initial import (migration phase),
being created by staff or can self-register themselves to the system.

Customers have to provide :ref:`label-contact-data` and get
:ref:`label-login-credentials` to login to the system.

Once logged in, customers get a 'My Eko-Disco' page where they can

- see their current orders

- watch their consumption

- order more services

- handle contractual problems

- get help if problems arise

- retrieve bills.

- reset their passwords if forgotten.

Customers can order :ref:`label-service`\ s and pay these (kinds of
payment depend on the type of service/good ordered and the available
payment methods).

Customers and their data can be managed by customers themselves (for
instance when postal addresses change), and by staff members.

Connected to: :ref:`label-contract` (1:|n0|),
:ref:`label-contact-data` (1:1), :ref:`label-login-credentials` (1:1).


.. _label-location:

Location
--------

A real-world location. Used for instance for meters to store
information about their place. Different to
:ref:`label-contact-address`\ es, locations can also be less formal,
for instance describing a location in words.

Connected to: :ref:`label-meter` (1:1)


.. _label-login-credentials:

Login Credentials
-----------------

A set of username/password assigned to system users. Passwords are
stored inside the system using strong cryptographic hash functions.

Passwords can be reset on request.

Connected to: :ref:`label-customer`


.. _label-meter:

Meter
-----

A meter measures power consumption. It has a place where it is
installed and might be connected to one or several contracts. For a
given time a meter can be connected to one or zero contracts.

Each meter has to provide a :ref:`label-location` that tells, where it
is installed.

Meters also contain a history of meter values
(:ref:`label-meter-value`), which is basically a list of meter values
at a given time.

Connected to: :ref:`label-contract` (|n0|:\ |m0|),
:ref:`label-meter-value` (1:|m0|), :ref:`label-location` (1:n)


.. _label-meter-value:

Meter Value
-----------

The value of a :ref:`label-meter` at a certain point in time
(providing a :ref:`label-timestamp`) authorized by some
:ref:`label-user` or device.

It serves mainly for computing power consumption of
:ref:`label-customer`\ s.

When a new meter value is added to the system (the respective
:ref:`label-meter` is 'updated'), the system also registers how the
the new value was entered, i.e. by whom and when.

The system will be prepared to collect meter values in two ways:

a) (push-method): by being fed with respective data by authorized
   users (staff members)

b) (pull-method): by polling dedicated hardware that provides the
   neccessary interface (automatic remote-reading).

The second choice requires appropriate hardware to be in place, which
in detail is not part of this specs. The system will, however, be
prepared to collect meter data from external devices.

Connected to: :ref:`label-meter` (|n0|:1), :ref:`label-timestamp` (1:1),
:ref:`label-user`.


.. _label-report:

Report
------

Administrative report or list to give overviews over current state of
business. Includes lists of customers sorted by various categories
(type of contract, amount of fees paid, etc.), lists of services
sorted by various categories, etc.

Reports are generated as PDF documents and are available for download
by authorized :ref:`label-user`\ s.

Connected to: (almost everything else)


.. _label-service:

Service
-------

The system will provide different services to
:ref:`label-customer`\ s. These can have arbitrary forms, including
one-time services (like installation of meters) and open-ended
long-time services (like delivering power based on contract). Services
are managable by staff like goods offered in a shop.

Services define the conditions under which they can be ordered by
:ref:`label-customer`\ s, including prices, runtimes, etc.

Services also serve as factories for :ref:`label-contract`\ s.

Connected to: :ref:`label-contract` (1:|n0|),

Used in the following use cases:


.. _label-timestamp:

Timestamp
---------

A timestamp can be a calendar date or a calendar date plus some day
time.

The system will internally use UTC-based timestamps only to minimize
ambiguities. In menus, frontends, etc. timestamps are displayed in
local Lagos time.

Connected to: :ref:`label-meter-value` (1:1),
:ref:`label-contact-email` (1:1)


.. _label-transaction:

Transaction
-----------

A transaction is some business-relevant action taken. A transaction
means basically, that something happened, that leads to increased or
decreased customer accounts. Normally this is something like a
payment, some service order or similar.

Transactions do always belong to one certain customer account. They
also contain some amount of money which is thereby transfered to or
from a customer's account. They also always reference a service which
is consumed, purchased, or (pre-)paid by the respective customer.

Connected to: :ref:`label-customer` (1:|n0|), :ref:`label-service`
(|n0|:1)

Used in the following use cases:


.. _label-user:

User
----

A system user.

Users can have :ref:`label-user-role`\ s managed by the
system. Real-world staff members and customers are different to the
system as they will have different roles. Also anonymous users are
accepted by the system to provide marketing pages, service offers,
etc.

Each user has one set of :ref:`label-login-credentials` to authenticate
against the system.

Users can be blocked or removed from the system.

Connected to: :ref:`label-login-credentials`.


.. _label-user-role:

User Role
---------

A role assigned to a group of :ref:`label-user`\ s.

Connected to: :ref:`label-user` (1:|n0|).


.. [#] Relation types: (1:1): One-to-one, (1:n): One-to-many, (n:1):
       many-to-one, (n:m): many-to-many. ``n`` and ``m`` mean some
       value ``1..n``. To indicate zero or more (``0..n``) relations,
       we use |n0| and |m0| respectively.