Data and Process Modeling Databases Demystified

Entity Relationship Modeling Entity relationship modeling is the process of visually representing entities, attributes, and relationships, producing a diagram called an entity relationship diagram. Peter Chen developed the original ERD format in 1976.

Chen’s Format

The Relational Format Over time, an ERD format known generically as the relational format evolved. It is used by several of the better-known data modeling software tools, including PowerDesigner from Sybase and ER/Studio from Embarcadero Technologies, and in popular general drawing tools such as Visio from the Microsoft.

The IDEF1X Format The Computer Systems Laboratory of the National Institute of Standard and Technology released the IDEF1X standard for data modeling in FIPS Publication 184. The standard covers both a method for data modeling as well as the format for the ERDs produced during the modeling effort. It is widely used and understood across the information technology industry and is a U.S. Federal Government standard.

Super Types and Subtypes

Process Models Flowchart ◦(or structure chart) is probably the oldest form of computer systems documentation.

The Function Hierarchy Diagram Shows all functions of a particular application system or business process, organized into a hierarchical tree.

The Swim Lane Diagram Gets it name from the vertical lanes in the diagram, which resemble the lanes in a swimming pool. Each lane represents an organizational unit such as a department with process steps placed in the lane for the unit that is responsible for the step. Lines with arrows show the sequence or control flow of the process steps.

The Data Flow Diagram The most data centric of all the process diagrams. Instead of showing a control flow through a series of process steps, it focuses instead on the data that flows through the process steps.

Relating Entities and Processes Use CRUD matrix (Create, Read, Update, Delete)

Problems: A customer wants to order an item from a fast-food store via an online self-service kiosk system. To accomplish this, the customer inputs his order via the kiosk's touch screen user interface (UI). The UI logic will make calls to the order service layer to compute the total payment for the order. Once the customer approves the total cost of the order, the system will proceed to process the payment. The system will then input the order details into the order database and provide a notification to the customer.

A customer orders an item from a fast- food counter. To accomplish this, the customer states his order to the cashier. Once he has ordered, the customer pays the cashier for the food item. The customer then receives the item ordered. If for some reason the order is cancelled after having paid for the item already, the customer is refunded.