| = Shopping Cart example architecture |
| |
| include::ROOT:partial$include.adoc[] |
| |
| This tutorial shows how to build the functionality for a Shopping Cart system. When complete, end users will be able to add items to a cart and checkout, creating an order. As shown in the following illustration, the system includes three services that use xref:concepts:akka-grpc.adoc[Akka gRPC] and Kafka as transport mechanisms: Cart, Order, and Analytics. |
| |
| image::example-overview.svg[Example overview] |
| |
| Each user's cart is represented by a Cart Entity. Cart state is persisted using xref:concepts:event-sourcing.adoc[Event Sourcing]: When a user updates their cart, the Entity persists events in an _Event Journal_ database. Using xref:concepts:cqrs.adoc[Command Query Responsibility Segregation] (CQRS), which separates read and write responsibility, {akka-projection}/[Akka Projections {tab-icon}, window="tab"] provide the data necessary for the Order and Analytics services. |
| |
| The `PopularityProjection` uses the events from all shopping carts to store a representation in the database to answer queries of how popular the items are. |
| |
| Follow the steps in the tutorial to build functionality a bit at a time and try running it as you go. |
