Specifying Entity Sets and Entity Instances

Specify Entity Sets and Entity Instances

A rulebase data model may also include a number of entities which have attributes attached to them. There are a number of rules that need to be observed when setting data for an entity:

The Global Entity can be expressed as an Entity in the Entity Set "global" and attributes can be set to it.
Entities can be associated with each other through relationships.

Example:

If we had a rulebase with the following entity model:

In this case there are two types of entities (apart from the ever-present global entity) the person entity and the animal entity. Any person can have two relationships (in this example both relationships are "to-many":

The first is to an animal and the relationship is a pets. That is to say that the person has pets which can be more than one an animal.
The second relationship is to another person entity and the relationship is a children relationship. That is to say, that the person has children which can be more than one person.
The entity label is an XSD:ID and must be unique within the session data, even for instances of different types of entities.
The relationship target attribute refers to an entity label and is an XSD:IDREF.
The target of a relationship must be defined in the session data. You cannot have a relationship to a non-existent entity.

1   <list-entity entity="person">
2     <entity label="Bob Smith">
3       <attribute id="name"> 4         <text-val>Bob Smith</text-val> 5       </attribute> 6       <relationships> 7         <relationship name="pets"> 8           <target ref="snoopy" /> 9         </relationship> 10        <relationship name="children">11          <target ref="Bob Jr" /> 12        </relationship> 13      </relationships> 14    </entity> 15 16    <entity label="Bob Jr"> 17      <attribute id="name"> 18        <text-val>Bob Jr</text-val> 19      </attribute> 20      <relationships>21        <relationship name="pets"> 22          <target ref="snoopy" /> 23        </relationship> 24      </relationships> 25    </entity> 26 </list-entity> 27 28 <list-entity entity="pet"> 29    <entity label="snoopy"> 30      <attribute id="name"> 31        <text-val>Snoopy</text-val> 32      </attribute> 33      <attribute id="has_fleas"> 34        <text-val>false</text-val> 35      </attribute> 36    </entity 37 </list-entity>

In the above example:

There are two person entities "Bob Smith" and "Bob Jr" and one animal "Snoopy".
Bob Smith has a relationship "pets" to Snoopy.
Bob Smith also has a relationship "Children" to Bob Jr.
Bob Jr has a relationship pets to Snoopy, so you could sat that Snoopy is a pet of Bob Smith and also a pet of Bob Jr.

See also:

Setting Session Data - Generic Data

Specifying an attribute's values

Determining an attribute's value

Returning a Decision Report