July 18 18:20~19:41 ▲Figure 1: A recent picture from the book “Clean Architecture” foreword Figure 1 is a picture recently implemented in the book “Clean Architecture”. Although Teddy started to implement Clean Architecture mainly by referring to this picture, Teddy always felt that there was something wrong with this picture. At the beginning, only a …
Talk about the implementation of Clean Architecture again Read More »
July 9 14:20~16:20 ▲NotifyBoard implements Idempotent architecture diagram foreword Teddy introduced why Event Handler needs to have Idempotent in <Event Sourcing (16): Event Semantics and Idempotent in Distributed Systems>. This episode takes the Event Handler—NotifyBoard that generates GetBoardContent in the ezKanban system as an example (please refer to <Event Sourcing (10) ): Implement Projector ＞), …
July 7 18::09~19:21; 21:15~23:23; July 8 13:45~16:27 ▲Store Checkpoints in the Event Store foreword Although using EventStoreDB, a database specially designed for Event Sourcing and CQRS, can reduce a lot of development work, in practice developers may only use relational databases due to company requirements or project constraints. In this case, you must simulate the …
Event Source (17): Read the events stored in the hand-carved Event Store Read More »
July 6 23:14~24:00; July 7 00:00~01:39 ▲I’m almost exhausted XD foreword The reason why villagers use Event Sourcing and CQRS is to develop microservices in many cases. The microservice architecture is a distributed system. Compared with the centralized system, the distributed system has the characteristics of heterogeneity, easy expansion, robustness, high fault tolerance and low …
Event Sourcing (16): Event Semantics and Idempotent for Decentralized Systems Read More »
July 05 21:59~23:12 ▲Figure 1: Behavior is uncontrollable foreword The last episode discussed the topic of event versioning, this episode will discuss Behavior Versioning. This problem Teddy also read Gregory Young’s ” Versioning in an Event Sourced System ” and found that if he did not notice the “behavioral version” of the program, in the …
July 05 18:08~19:23; 20:07~21:06 ▲Figure 1: Do cats need to do version control? foreword Because Event Sourcing treats events as a single source of truth , events are themselves an API. The event revision is like the API revision. It is a very important issue for the Event Sourcing system. If the events of different …
July 04 21:23~23:39 ▲Figure 1: Using snapshots to accelerate Aggregate read speed foreword The Event Sourcing system is very simple and fast on the writing side, but reading because it needs to use all the domain events to which the Aggregate instance belongs to get the latest status one by one, it often makes people …
Event Sourcing (12): Snapshots to Accelerate Aggregate Reads Read More »
Original link: https://teddy-chen-tw.blogspot.com/2022/07/12.html July 04 21:23~23:39 ▲Figure 1: Using snapshots to accelerate Aggregate read speed foreword The Event Sourcing system is very simple and fast on the writing side, but reading because it needs to use all the domain events to which the Aggregate instance belongs to get the latest status one by one, it …
Event Sourcing (12): Snapshots to Accelerate Aggregate Reads Read More »
Original link: https://teddy-chen-tw.blogspot.com/2022/07/12.html July 04 21:23~23:39 ▲Figure 1: Using snapshots to accelerate Aggregate read speed foreword The Event Sourcing system is very simple and fast on the writing side, but reading because it needs to use all the domain events to which the Aggregate instance belongs to get the latest status one by one, it …
Event Sourcing (12): Snapshots to Accelerate Aggregate Reads Read More »
Original link: https://teddy-chen-tw.blogspot.com/2022/07/11javascripteventstoredb.html July 04 18:38~19:46 ▲Figure 1: User-defined projection program of EventStoreDB foreword The previous episode introduced how ezKanbana implements Projector to generate the data required by the Read Model in the PostgreSQL database. This episode uses the customized Projection function of EventStoreDB to create another form of Read Model. *** Generate event projection …
Event Sourcing (11): Writing JavaScript to Generate Custom Projections in EventStoreDB Read More »
Original link: https://teddy-chen-tw.blogspot.com/2022/07/11javascripteventstoredb.html July 04 18:38~19:46 ▲Figure 1: User-defined projection program of EventStoreDB foreword The previous episode introduced how ezKanbana implements Projector to generate the data required by the Read Model in the PostgreSQL database. This episode uses the customized Projection function of EventStoreDB to create another form of Read Model. *** Generate event projection …
Event Sourcing (11): Writing JavaScript to Generate Custom Projections in EventStoreDB Read More »
Original link: https://teddy-chen-tw.blogspot.com/2022/07/8cqrs.html July 02 06:35~08:20 ▲Figure 1: ezKanban applies CQRS architecture diagram foreword CQRS is the abbreviation of Command Query Responsibility Segregation , which is translated into ” command and query responsibility separation ” in Chinese. Today we introduce what CQRS is and what problems it can solve. *** origin CQRS is a design …
Original link: https://teddy-chen-tw.blogspot.com/2022/07/8cqrs.html July 02 06:35~08:20 ▲Figure 1: ezKanban applies CQRS architecture diagram foreword CQRS is the abbreviation of Command Query Responsibility Segregation , which is translated into ” command and query responsibility separation ” in Chinese. Today we introduce what CQRS is and what problems it can solve. *** origin CQRS is a design …