Java HTTP/REST Micro-service

A micro-service implementation in Java 21, Spring Boot 4.0.x.

flowchart LR

    subgraph springboot["Spring Boot Application"]
        direction TB
        endpoint["/endpoint\n(Controller)"]
        service["Service"]
        schema["Schema JAR"]
        endpoint --> service
        endpoint --> schema
    end
    
    subgraph tomcat["Tomcat 11 (Servlet Container)"]
        direction TB
        connector["HTTP Connector\n(port 8080)"]
        threadpool["Thread Pool\nserver.tomcat.threads.max=4"]
        dispatcher["DispatcherServlet\n(Spring MVC)"]
        connector --> threadpool --> dispatcher
    end

    client(["HTTP Client"])
    
    client -->|"HTTP request"| connector
    dispatcher -->|"route"| endpoint
    service -->|"HTTP response"| client

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Table of Contents

• Unit Tests
• Run Application
  • Environment Profiles
  • Verify the Endpoint
• Build Artifact
• App Start Time
• Monitoring
• Build & Run in Docker (Single Core)
• Deployment & Load Balancing
• Performance
• See Also

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Unit Tests

## using gradle build tool
./gradlew clean test

## using maven
## mvn test

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Run Application

Application can be run with different profiles. In a typical development cycle, a software goes through multiple environments — local, dev, test, stage/prod-like, and finally production.

Environment-specific configuration is stored in properties files under src/main/resources.

Environment Profiles

Configuring application.properties with a profile

export SPRING_PROFILES_ACTIVE=dev
## or set spring.profiles.active=dev in application.properties
./gradlew run

## You will see logs mentioning the active profile
#2022-12-29 20:13:37.946  INFO INFOid --- [           main] c.a.RESTApplication : The following profiles are active: dev

In higher environments, the infrastructure team typically sets an environment variable that can be mapped to spring.profiles.active:

## If environment machines have env APP_ENVIRONMENT available
export APP_ENVIRONMENT=production
## assign the value of APP_ENVIRONMENT to spring.profiles.active
## in application.properties
spring.profiles.active=${APP_ENVIRONMENT}

Verify the Endpoint

curl -v -XGET http://127.0.0.1:8080/retailstore/health-blocking | python -m json.tool
Note: Unnecessary use of -X or --request, GET is already inferred.
*   Trying 127.0.0.1:8080...
> GET /retailstore/health-blocking HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.79.1
> Accept: */*
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 200
< Content-Type: application/json
< Transfer-Encoding: chunked
< Date: Fri, 30 Dec 2022 21:55:50 GMT
<
{ [94 bytes data]
* Connection #0 to host localhost left intact
{
    "timestamp": 1672433750,
    "applicationName": "retailstore-rest",
    "applicationVersion": "1.0"
}

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App Start Time

Java	Spring Boot	Startup
21	4.0.0	695 ms

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See Also

• https://github.com/parayaluyanta/retailstore-microservice-nio (~6.978ms/request)
• https://github.com/lamatola-os/chat-server_reactive-spring (~22.860ms/request)
• https://github.com/lamatola-os/akka-http-benchmark (~1.172ms/request)
• https://github.com/lamatola-os/netty-microservice (~1.280ms/request)
• https://github.com/prayagupd/nodejs-microservice