Rules Language

CER is a language for defining questions that can be asked, and the rules for determining the answers to those questions.

Each question specifies:

• its name;
• the type of data which provides the answer to the question; and
• the rules for providing the answer (if the question is asked).

The answer to a question can be as simple as yes or no, e.g. the question "Is this person eligible to receive benefit?"; however, CER lets you define answer types to be as complex as you need, e.g. the question "Which groups of people in the household have an urgent need?" would be answered by providing a list of household groups, with each household group containing a list of people.

The rules for determining the answer to a question again can be as simple or as complex as you need, e.g. the rule for the answer to the question "What is the claimant's date of birth?" is likely to (trivially) be "the date that the claimant declared their date of birth to be", whereas the rule for answering the question "Is this person eligible to receive a benefit?" is likely to involve further questions such as "What level of income does this person have?" and/or "How many children does this person have?".

CER has its own terminology for these concepts:

• Rule Class

  A rule class is a type of "thing" which has data, such as a Person, an Income or a Claim. A new rule class can be created in the CER Editor. See Technical View

• Rule Object

  A rule object is an instance of a Rule Class, e.g. John Smith (a Person), John Smith's income from his part-time job (Income), or John Smith's application for child support benefits (Claim).

• Rule Attribute

  A rule attribute is a question that can be asked. It is defined on a Rule Class and may be asked of any Rule Object of that class, e.g. the Person rule class may define the dateOfBirth rule attribute, and so the John Smith rule object may be asked its dateOfBirth, (e.g. 3rd October 1970). A new Attribute can be created for the selected rule class in the CER Editor. See Technical View

• Expression

  An expression is a calculation step which can be used to answer a question, e.g. if the eligibility of a claim depends on a person's total income being below a certain threshold, we can use a "sum" expression to calculate the total income and then use a "compare" expression to compare that total with the threshold amount. In order to create an expression, a "sum" rule element can be dragged to the rule attribute in the CER Editor. See Business View

• Rule Set

  A rule set is a collection¹of rule classes, typically centered around a specific purposes, e.g. a rule set for child benefit determination might include the rule classes Claim, Person and Income. A new rule set can be created in the Rules and Evidence section of the Administration Interface.

• Rule Session

  A rule session controls the running of rules, e.g. your application might create a rule session to determine John Smith's eligibility for child benefit, by invoking the appropriate rule set and asking eligibility questions regarding John's personal circumstances.