Create Domain Read model for Todo.

[hyunbin7303]

For the eventsourcing-CQRS pattern, it separates write side(Command) and read side(Query). For the read side, it is desirable to create its own read domain entity for the Todo.

Read model - > any complex logic they encaplsuation is executed asynchronously during event projection. A read model projection function can access existing persistent data, run calcuations of any complexity, and generate as much new or modified data as necessary. The loger a projection takes, the greater the latency of the system,

• [x] Create Todo Read model
• [x] Create IBaseRepository for Read Data query.

[hyunbin7303]

source from : https://cqrs.nu/tutorial/cs/03-read-models

A read model is a model specialized for reads, that is, queries. It takes events produced by the domain and uses them to build and maintain a model that is suitable for answering the client's queries. It may build and maintain...

• An in-memory model of the data.
• A relational model of the data, stored in an RDBMS.
• Documents, stored in a document database.
• A graph model of the data, stored in a graph database.
• A search index.
• An xml,csv, excel sheet etc.

[hyunbin7303]

https://www.ibm.com/cloud/architecture/architectures/event-driven-cqrs-pattern/

[hyunbin7303]

Projections

TodoDetails or TodoViews (Read models) are not the only possible outcome of events streaming processing. Such streams can be used for various tasks.

• Share events between microservices. From the message bus --> Notification service && analytics service && Read model db.

• We need Read model because:

• Query the state of a single aggregate is not the only query you want.

• You might need to query across many aggregates, or different aggregate types.

• You don't need to return the full aggregate state, but only a subset of it.

https://blog.eventuous.dev/read-models-in-event-sourced-systems-489342181233