This is Part 4 in my series on Event Discovery techniques. In this post, I will describe how to use the major entities that you have identified as a starting point.
In the course of your requirements analysis you will have identified some entities for which you will be required to keep persistent data (these entities will translate into tables in your database when you are in the Design Phase). For each of these entities, you can discover the life-cycle (and therefore, the Events) by asking these questions:
- What are the Create Events for an instance in this Entity? These are the Events in which your “business” first becomes aware of a specific instance of this Entity, and stores initial data.
- What are the Read Events for an instance in this Entity? These are the Events that trigger usage of the data for this Entity without modifying the data.
- What are the Update Events for an instance in this Entity? These are the Events which cause any of the data elements stored for this Entity to be modified.
- What are the Delete Events for this Entity? These are the Events which cause “end of life” (defined as “there will be no more need to read or modify this instance”) for an instance in this Entity.
An acronym sometimes used for this analysis is “CRUD” (Create, Read, Update, Delete).
Here are some examples:
Let us say the scope of our “business” is to add the selling of refrigerated beverages in retail stores. Some Entities you might have identified are “Store” and “Product”. Let us examine each of these using CRUD.
- The Create Event might be “Store is opened”. That would lead you to ask questions such as “How do we get refrigerators to new stores?” and “How do we get the initial inventory of product to new stores?”. The answers lead to more Events.
- Some Read Events are “Inventory or Sales requests by Store, Region, or Territory”.
- Some Update Events can be “Store temporarily closed for remodel” or “Store commencing a going out of business sale”. This would lead you to ask questions such as “What do we do with existing inventory of refrigerated product?”.
- A Delete Event would be “Store is closing”. This leads you to questions such as “What do we do with the refrigerators and the inventory contained within?”
- The Create Event could be “Product is ordered”. This would lead you to ask questions such as “How do you know you need to order product?” and “How do you know how much of each type to order?”. The answers will certainly lead to new Events.
- A Read Event might be “Requests for Sales by product type”.
- Some Update Events are “Product is sold” and “Product is restocked”.
- A Delete Event could be “Specific Product type discontinued”.
Keep doing this for all of your identified Entities. You may be surprised how enlightening this is, revealing many Events that other forms of analysis would miss. Keep in mind, once you have identified new Events and added them to your Event List, you will fill in the detail for each column in the list and do the analysis of the Event Outputs described in a prior post.
In the next post I will describe how to use the data elements in the Entities to discover more Events.