🌅Day 2

Commands

• Can be used for organizational purposes. Such as starting/ending a microservice.

Users (Entities)

• nouns

• Steps

  • Define Timeline

  • Define Events

  • Define entities

  • Define bounded context

Focus Beings to Shift to User

As we begin to understand the users and commands and their relationship to events, we start to explore more complex systems and see how the architecture evolves.

The Picture That Explains Everything

Read Model

• not just data, it is a decision-making tool

• timesheet example:

  • how to figure out a timesheet if you are three weeks late for updating?

    • google calendar

    • phone history

    • GitHub comment history

The user issues their commands based on the inbound information from the read models. Let's start identifying those.

Introducing Read Models

Policies

Digging further, we uncover policies.

• How is the system supposed to react to given events?

• Whenever an event occurs, then the command.

Understanding Policies.

Aggregates

Finally, we start to see collections of commands or states, etc, which we will call aggregates.

• state machine logic

• focus on behavior, not data

• postpone naming

Example Aggregate

Designing a New Feature for a Web App (warning: incomplete thought alert)