design

GUI:

For error messages, GMAIL uses a CSS pop-up window with a "OK" button and
a close X in the top right corner. It causes the background (the rest of
the page) to fade, and has a blurred drop shadow. It feels rather minimalist.



Glossary:
========

- "Current property": the specific property within the events contained
within a rota that is to be assigned a value when the rota is next optimised.

- "Event": is a specific set of values for the properties declared by the
corresponding event type. In other words, an event is an instance of an
event type. Each property can be in one of three states:

   1) "Frozen": The property has a value (i.e a "resource" has been
   associated with the property), and that value cannot be changed by
   subsequent rota optimisation.

   2) "Set": The property has a value, but that value can be changed by
   subsequent rota optimisation.

   3) "Clear": The property has no value.

- "Event type": declares the properites of a class of event. E.g a "church
service" event type may have properties such as "Time", "Venue", "Primary
Steward", "Secondary steward", "Organist", etc. All event types will
include a "label" property, which holds a unique textual identifier for
each specific event.

- "Resource": A single value to which an event property may be set. In
general, there will be a range of values to which an event property could
be set. Each one of these values is a separate resource. So for instance,
a "church service" event, has a property called "Organist" which can be
set to the value "Enid", "Ben", "Carol" or "Lynne". In this sense,
"Enid", "Ben", "Carol" or "Lynne" are all resources. Each resource has an
"owner" who has the authority to say whether the resource can be used for
a particular event.

- "Rota": A collection of events. The properties of these events may be
any of the three states "frozen", "set" or "clear".

- "Rota optimisation": the action of ensuring that all events in a rota
have a defined value for the "current property". Events that have
"frozen" value for the current property are left unchanged. Other events
are modified by assigning a new value to the current property.


Actions:
=======

- Create a new event type
- Edit an existing event type
- Create a new rota
- Edit an existing rota
- Optimise a rota with respect to a named event property (the "current property").
- Request resource owners to indicate availability of resources for each event
  in the rota.





To create a new rota:
====================

1) Select an existing event type, or create a new custom event type by
modifying an existing event type by adding new named properties

2) Define the set of values (i.e. resources) that can be assigned to each
property. Optionally, define the "owner" (name, email, etc) of each
resource. Any resources left with no owner are implicitly owned by the
rota creator.

3) Loop round, creating the individual events to include in the rota.
Assign resources to any event properties that are known in advance and
should not be changed when the rota is optimised. These properties are
set to the "frozen" state (all others are left in the "clear" state). At
the least, each event should be assigned a unique textual label (or
accept the default auto-generated labels). Any properties left unassigned
here are assigned a value when the rota is optimised.


To optimise a rota:
==================

1) Select a specific event property as the "current property".

2) Email the owners of resources that may be assigned to the current
property to indicate there availability for each event. For each event
the owner selects "Available", "Not available", or "Available only if no
other resource is available". The owner may also indicate the maximum
number of rota events at which the resource can be used.