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Some quick thoughts...<br><br>Assume:<br><br>1. Previously relationships were attributes of a Person.<br><br>2. That you now want to represent a <span style="font-weight:bold;"><span>Relationship </span></span>as it's own concept.<br><br>3. That you define a Relationship (for now) as some connection between <span style="font-style:italic;">two </span>people (<span style="font-weight:bold;">Person</span>), such as a marriage, friendship, co-habitation, or common-law partnership etc.<br><br>4. <span style="font-weight:bold;">Relationship</span> could be further broken out into individual concepts like <span style="font-weight:bold;">Marriage </span>and <span style="font-weight:bold;">Friendship</span>, but for now assume this isn't required.<br><br>5. For now ignore the constraint (b
usiness rule) that one cannot be married to 2 people at the same time for simplicity. If interested, can include this.<br><br><br>Notes:<br><br>1. One now has two concepts - <span style="font-weight:bold;">Person </span>and <span style="font-weight:bold;">Relationship</span><br><br>2. Marry, Divorce, Separation, MakeFriend, UnFriend etc., are behaviors of the <span style="font-weight:bold;">Relationship </span>concept, <span style="font-style:italic;">not </span>the <span style="font-weight:bold;">Person</span>. In an object-oriented approach, an action on an object in the real world, becomes a behavior of the object being acted on. <span style="font-weight:bold;">Relationship </span><span style="font-style:italic;">knows about</span> marriage, friendships etc, not a <s
pan style="font-weight:bold;">Person</span>. A <span style="font-weight:bold;">Nail </span>knows how to be <span style="font-style:italic;">Hit</span>, not the <span style="font-weight:bold;">Hammer</span>.<br><br>3. Further to point 2, the <span style="font-style:italic;">Marry </span>behavior of Relationship needs to be supplied with 2 people (Person).<br><br>4. Further to point 3, the <span style="font-style:italic;">Marry </span>behavior of Relationship will be called and supplied with 2 people by something outside the domain within a transactional boundary by default. Are you Facebook? Look to a different transactional solution.<br><br>5. Constraints (business rules) can be placed within the proper concept because of point 2. A <span style="font-weight:bold;"
><span>Person </span></span>should not know of the constraints of marriage, friendship etc., <span style="font-weight:bold;"><span>Relationship </span></span>should. Likewise, a <span style="font-weight:bold;">Relationship </span>should not know the constraints of a <span style="font-weight:bold;">Person</span>. However, whenever <span style="font-style:italic;">creating </span>or <span style="font-style:italic;">deleting </span>a connection between the two, both sets of constraints should be evaluated.<br><br>5. Consider lazy loading to not involve related concepts where not required.
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