Java Implementation

运行方式

用./mvnw spring-boot:run运行 h2 database在 localhost:8080/h2-console

docker compose file for redis,rocketmq nad nacos in the root directory.

Redis

Redis acts as a caching service, increases application's ability to high traffic on the most popular products.
It also reduces the number of database operations which can saves costs if using a pay per use database service.

RocketMQ

RocketMQ is a open source messaging service that separates message producers from message consumers.
Therefore reduces coupling between different services.
It is similar to observer pattern but operates across different applications.

Nacos

Nacos is a registry that stores application properties and other variables that subject to change.
One of the use case is to act as some sort of environment variables manager.
It can also update those variables in real time without restarting the application.

Test

Redis

I logged in to redis-cli and checked the keys and values after creating products.
Then I restart the application so that the H2 database is cleared. However, the redis database continues to have the cached products. After restart the H2 database shouldn't have any products. If my GET request got a 200 response then it means the response is from the redis cache (cache hit).

RocketMQ

After the product is created, a listener will print to the console the name of the product.

Nacos

When I change the value of product.service.welcome-message in the nacos web console and refresh the page, the welcome message is updated without restarting the application.

Thoughts

The redis database setup is straightforward.
RocketMQ took a long time because I keep getting connection errors.
I have RocketMQ set up in docker on my linux machine with ip 10.10.2.71. My application is on my Windows machine.
It turns out, although I set up the address of the nameserver correctly as 10.10.2.71:9876, the applications gets the address of the broker from the nameserver. Which is an internal ip used by docker container. There is no way for me to manually set the broker address. So I have to move my application to the same linux machine. It works fine afterward.
I ran in to compatibility issues when I tried to set up nacos. I initially used the version of "spring-cloud-starter-alibaba-nacos-config" in nacos documentation, but it wasn't compatible with Spring Boot 3.5.4. I had to use the preview version of nacos