Overview
Before we start looking at Jazz Rules, let's identify what a Rule is in general terms.
What is a Rule?
Definition: Rules describe the definitions, constraints, and operations that apply to an object.
Consider the rule as a closed-ended question, i.e. the answer is yes or no. e.g. if the Time of Day is currently between 1 pm and 3 pm, or if the state of the object is currently 'Not started'. If the question is 'yes', then a set of operations or actions can be applied to the object.
e.g. A use case for a meeting may be: if today is one day before the meeting, send an email to the meeting participants reminding them of the meeting.
The constraint is 'if today is one day before the meeting' and the action is 'send an email to the meeting participants reminding them of the meeting'.
What are the steps involved in 'executing' a rule?
1. Determine if the rule applies to the object.
- Does this rule apply to this type of object. This is done by comparing the rule's definition to the type of object.
2. If the rule applies to the object, execute the constraints to determine the course of action.
- This is done by reviewing the rule's constraints against the object.
3. Follow the course(s) of action.
- this may consist of one or more steps, e.g. email or text me, set a specific property in the object to a result.
Implementation:
- Each rule consists of a container specific to a class of object that addresses one or more constraints (conditions).
- Each condition has zero or more actions that are applied to the object.
Example:
- Joe has a task that is due on Thursday.
- If the task is not finished, Remind Joe on Wednesday at 4pm that the task is due.
- 'If the task is not finished' is the condition.
- the reminder may be an email, a text message, a desktop notification.
- If the task is not finished, Notify Joe on Thursday at 4pm that the task is not finished.
- If the task is not finished, Notify Joe's Project Manager on Friday at 9am that the task is not finished.
- If Joe completes the task, notify the Project Manager of the completion.
Jazz Rules
Figure 1: Rule Conditions
Figure 2: Rule Actions
Conditions
Figure 3: If Day of Week Condition
Figure 4: If then else Condition