Attributes of Business Objects AwareIM Documentation

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====== Attributes of Business Objects ======

Now that we have defined business objects and relationships we can define attributes of each business object. There are two types of attributes –simple attributes (text, number, date, picture etc) and those representing relationships or //[[2000_concepts:0200_basics:0400_reference_attributes|references]]//).

Values of some attributes are entered by users, whereas values of other attributes are always calculated by the system and never entered by users. The latter attributes are called //calculated// attributes.

By carefully studying the requirements we can identify the following attributes of the objects:

===== Item Object =====

^Attribute^Type^Description^
|''Title''|text| |
|''Author''|text| |
|''Code''|text| |
|''Description''|text| |
|''Picture''|image| |
|''Location''|text| |
|''InternalStatus''|text|possible values ''Released'' and ''Withdrawn''|

==== Reference====
see the relationships of the Item object
^Reference^Description^
|''Type''|a reference to the single ItemType object that the Item belongs to|
|''Loans''|a list of Loan objects for the item, calculated|
|''Reservations''|a list of Reservation objects for the item, calculated|

===== ItemType Object =====
^Attribute^Type^Description^
|''Name''|text|Book, CD, Video etc)|
|''MaxBorrowNumber''|number| |
|''MaxLoanPeriod''|number| |
|''MaxRenewals''|number| |

===== Member Object =====
^ Attribute      ^ Type                         ^ Description                                          ^
| ''FirstName''   | text                         |                                                      |
| ''LastName''    | text                         |                                                      |
| ''Address''     | text                         |                                                      |
| ''DateOfBirth'' | date                         |                                                      |
| ''Gender''      | text                         | ''Male'' or ''Female''                               |
| ''EmailAddress''| text                         |                                                      |
| ''MemberNumber''| number                       | unique number associated with a member - calculated  |
| ''Photo''       | picture                      |                                                      |
| ''Status''      | text                         |''Active'' or ''Suspended''                           |

==== References==== 
^ Reference         ^ Description                                ^
| ''Loans''         | a list of Loan objects, calculated         |
| ''Reservations''  | a list of Reservation objects, calculated  |
| ''Fees''          | a list of Fee objects, calculated          |
| ''Payments''      | a list of Payment objects, calculated      |

===== Loan Object =====
^ Attribute      ^ Type                         ^ Description                                           ^
| ''DueDate''    | date                         | the date the loan is or was due                       |
| ''ReturnDate'' | date                         | the date the loan was returned - calculated           |
| ''Status''     | text                         | ''New'', ''Current'', ''Past'' - calculated           |

==== References ====
^Reference^Description^
|''Member''|reference to a single Member object, calculated|
|''Item''|reference to a single Item object, calculated|

===== Reservation Object =====
^Attribute^Type^Description^
|''ReservedOn''|timestamp|the date and time when the reservation was made, calculated)|
|''BorrowedOn''|timestamp|the date and time the reservation was borrowed, calculated)|
|''ItemOfferedOn''|timestamp|the date and time the reservation was offered, calculated)|
|''Status''|text, calculated|''New'', ''Waiting'' – if reservation is waiting for item to be returned,\\  ''Offered'' – if reservation has been offered but not taken up,\\ ''Converted'' – if reservation has been taken up,\\  ''Cancelled'' – if reservation has been cancelled by owner,\\ ''Expired'' – if reservation has expired|

==== References ====
^Reference^Description^
|''Item''|a reference to a single item that has been reserved, calculated|
|''Member''|a reference to a single member who made the reservation, calculated|

===== Fee Object =====
^Attribute^Type^Description^
|''Amount''|number| |
|''Description''|text| |
|''AppliedOn''|date |the date the fee was charged, calculated|

==== References ====
^Reference^Description^
|''Member''|reference to a single member who was charged, calculated|

===== Payment Object =====
^Attribute^Type^Description^
|''Amount''|number| |
|''Description''|text| |
|''AppliedOn''|date|the date the payment was made, calculated|
|''Status''|text|''New'' or ''Applied''|

====References====
^Reference^Description^
|''Member''|reference to a single member who made a payment, calculated|
In addition we will introduce a few attributes that will display summarized information to the user:

===== Item Object =====

^Attribute^Type^Description^
|''Available''|yes/no|this is the flag that indicates whether the item is available. In principle, this information can be derived from the information about loans associated with the item. It is, however, very convenient to immediately show to the user whether the item is available (both in queries on item or in the item form)|
|''CurrentReservation''|Reference|this is a reference to the reservation that is the first in the queue of reservations. We define this attribute purely for convenience to avoid calculating it every time it is needed (it will be needed by a number of rules).|

===== Member Object =====
^Attribute^Type^Description^
|''OutstandingCharges''|Number |Indicates whether the member owes something to the library. Again, in principle, this information can be derived from the information about fees and payments, however, it is very convenient to show this number to the user.|