Quick Glossary

Aggregate

A group of objects that represent a domain concept and need to be consistent together

Aggregate Root

The entry point to an aggregate, enforcing the invariants

Bounded Context

A system which shares domain language

Invariant

A condition that is always true

Unit of Work

A pattern to ensure all transactions succeed or fail together

Sample: Modeller

Column: Commands

• Create Column
• Rename Column
• Change Data Type
• Make Primary
• Clear Primary

Invariants

• A date column cannot be a primary key

Some Issues...

• That UoW stuff is a little invasive, and brittle
• So is that IEventBus dependency
• Did you spot the bug?

Write Model

Name: New Column Name

Data Type: Date

Primary Key? No

Read Model

Name: New Column Name

Data Type: Date

Primary Key? Yes

Multiple Sources of Truth