	Design of the database modules
	------------------------------

GOALS AND WANTED FEATURES

* The framework should support several kind of data :
  - ticks (Price, Volume, Datetime)
  - quotes (Bid, Ask, Bid_size, Ask_size, [bid_exchange], [ask_exchange], Datetime)
  - bars (Open, High, Low, Close, Volume)
  
* Each module may not be able to provide all kind of informations.
  They provide a set of informations :
  - historic prices (historic prices in ticks or in bars, depending on the
    case)
  - current prices (the prices of the day, the prices in real time)
    possibly for many stocks (whereas the historic prices are always 
    only provided for a single stock)
  - metainformations
  - list of stock codes/names (market, personal lists, ...)

* A module may additionnaly provide the possibility to modify/add data.

* A module common to all DB modules could provide features to work with
  several DB modules :
  - synchronization of a writable DB with another DB
  - verify the accuracy of the prices of a DB by comparing it to
    another DB
  - find the most up-to-date DB
  - choose the good DB module based on some requirements (eg CURRENT_PRICE |
    HISTORIC_PRICE | 5MIN_BARS)
  - apply split on the databases
    - stores the split as metainformation (in the first writable metainformation
      DB module) if it isn't stored yet
    - apply the split on all writables DB modules where it hasn't been
      applied yet
    
MEANS AND IDEAS OF IMPLEMENTATION


PROPOSED DESIGN


PROBLEMS


