Grokking Microservices Design Patterns

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CQRS Pattern: An Example

Let's consider a simple application that manages user profiles. In this application, you can create a new user (command), update their email (command), and view user details (query).

1. Command Model (Write Model)

  1. Command Class: Defines an action to be performed. For instance, CreateUserCommand with fields like userId, name, and email.
  2. Command Handler: Processes the commands. It would take CreateUserCommand, perform business logic, and persist the changes.
  3. Domain Model: Represents the state of the data (e.g., a User class). 4

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Sila Setthakan-anan

Sila Setthakan-anan

· a year ago

SimpleBusQuery's constructor will receive only 1 parameter.

But in the Putting it All Together section show us init SimpleBusQuery's instance with 2 arguments.

Ihor Luhovyi

Ihor Luhovyi

· 3 months ago

In Event Sourcing, I understand that domain events are stored in an Event Store — but why do we store events instead of just saving the current state like in a regular database? And does that mean read operations (like checking a balance) also get stored as events, or only write operations that change state?