DEV Community: Linh Truong Cong Hong

Build a microservices system with Java Spring Boot

Linh Truong Cong Hong — Sun, 06 Feb 2022 14:36:19 +0000

Github repo for this project: (Please give me a Github star ⭐ for this effort! Thank you!)

https://github.com/linhtch90/microservices-java-demo-zoo-devto

Introduction

Microservice is the concept of decomposing a large monolith application into small, independent, distributed services. This could improve the flexibility, scalability and resiliency of the whole system.

The introduction of Spring Cloud framework makes it easier for developers to build and deploy microservices to private and public clouds. This framework has wrapped a wide varieties of popular cloud-management microservices frameworks under a well-organized framework.

In this blog post, I want to help you have an overview about Spring Cloud framework by building a simple microservices system with Spring Cloud step by step. This system includes the following components:

Configuration server
Service discovery with Eureka
2 demo microservices called Tiger and Panther
Gateway server
RabbitMQ for messaging between microservices

The relationships between those services are described as the following figure.

Let's begin building this system!

Configuration server

Go to start.spring.io and generate a new project with the following information:

Group ID: com.microservices.zooconfsvr
Artifact ID: microservice-zoo-config-server
Name: microservice-zoo-config-server
Description: zoo microservices config server
JDK: I am using JDK 17 for this tutorial. I have not tested this project with older JDKs yet!
Dependencies: Config Server (So other services can get their configuration information from this service)

Your pom.xml should look like this:

<dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-bootstrap</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-config-server</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

In folder src/main/resources/, add a file called bootstrap.properties
In folder src/main/resources/, add a folder called config/ and create 4 configuration files eureka-server.properties, gateway-server.properties, panther-service.properties, tiger-service.properties
The content of those .properties files could be found in my Github repo I put the link on top of this blog post)

Add @EnableConfigServer annotation to the main entrance class MicroserviceZooConfigServerApplication.java.

Service discovery (with Eureka)

Go to start.spring.io and generate a new project with the following information:

Group ID: com.microservices.zooeurekasvr
Artifact ID: microservice-zoo-services-discovery
Name: microservice-zoo-services-discovery
Description: zoo microservices services discovery
Dependencies: Eureka server, config client

Your pom.xml should look like this:

<properties>
        <java.version>17</java.version>
        <spring-cloud.version>2021.0.0</spring-cloud.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-bootstrap</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-config</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-loadbalancer</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

In folder src/main/resources/, add a file called bootstrap.properties
The content of those .properties files could be found in my Github repo (I put the link on top of this blog post)

Add @EnableEurekaServer annotation to MicroserviceZooServicesDiscoveryApplication.java

Gateway server

Gateway server is the service that handles all request from client. Go to start.spring.io and generate a new project with the following information:

Group ID: com.microservices.zoogateway
Artifact ID: microservice-zoo-gateway
Name: microservice-zoo-gateway
Description: microservice gateway for the zoo demo
Dependencies: Eureka client, config client, gateway

Your pom.xml should look like this:

<properties>
        <java.version>17</java.version>
        <spring-cloud.version>2021.0.0</spring-cloud.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-bootstrap</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-config</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-gateway</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

In folder src/main/resources/, add a file called bootstrap.properties
The content of those .properties files could be found in my Github repo (I put the link on top of this blog post)

Add @EnableEurekaServer annotation to MicroserviceZooGatewayApplication.java

Tiger service

Go to start.spring.io and generate a new project with the following information:

Group ID: com.microservices.tigerservice
Artifact ID: microservice-tiger
Name: microservice-tiger
Description: microservice tiger
Dependencies: Eureka client, config client, web, client load balancer, open feign (also for load balancer), RabbitMQ

Your pom.xml should look like this:

<dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-bootstrap</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-loadbalancer</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.springframework.cloud/spring-cloud-starter-openfeign -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
            <version>3.1.0</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-config</artifactId>
        </dependency>
        <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-amqp</artifactId>
    </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

In folder src/main/resources/, add a file called bootstrap.properties
The content of those .properties files could be found in my Github repo (I put the link on top of this blog post)

Add @EnableFeignClients annotation to MicroserviceTigerApplication.java

Create com.microservices.tigerservice.service package and add 2 files ClientToPantherService.java for directly call Panther service and RabitMQSender.java for sending a string message to Panther via RabbitMQ.
Create com.microservices.tigerservice.controller package and add TigerController.java, specifying controllers for calling Panther service.
Create com.microservices.tigerservice.component package and add RabitMQSenderComponent.java for creating Beans related to messaging service.
Please refer to my Github repo for the content of these files.

Panther service

Go to start.spring.io and generate a new project with the following information:

Group ID: com.microservices.pantherservice
Artifact ID: microservice-panther
Name: microservice-panther
Description: microservice panther
Dependencies: Eureka client, config client, web, client load balancer, RabbitMQ

Your pom.xml should look like this:

<dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-bootstrap</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-loadbalancer</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-config</artifactId>
        </dependency>
        <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-amqp</artifactId>
    </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

In folder src/main/resources/, add a file called bootstrap.properties
The content of those .properties files could be found in my Github repo (I put the link on top of this blog post)

Create controller and other components for the services as follow.

Create com.microservices.pantherservice.controller package and add TigerCallPanther.java for directly respond to calls from Tiger service in the form of a string.
Create com.microservices.pantherservice.component package and add 2 files RabbitMQComponent.java and RabbitMQReceiver.java for settings related to listening and responding to messages sent from Tiger service. Right after receiving the message from Tiger service, Panther service print the message into the Log.
Please refer to my Github repo for the content of these files.

RabbitMQ

Please refer to this tutorial for using RabbitMQ with Docker.

Running the whole system

Please follow this order:

Start RabbitMQ with Docker (see above section)
Start Configuration server
Start Discovery service
Start Tiger service
Start Panther service
Start Gateway server

Testing microservices with Postman

Direct call from Tiger service to Panther service: Open Postman and send a request to

http://localhost:8074/tiger-service/tiger/callpantherservice

The response from Panther service is a string with content.

PANTHER RECEIVED CALL FROM TIGER

Send message from Tiger service to Panther service: Open Postman and send a request to

http://localhost:8074/tiger-service/tiger/sendmessagetopanther

There is not any response in Postman. It is okay. Please go to the terminal screen where you are running Panther service. You will see a log message saying:

Received message is: Message from Tiger to Panther via RabbitMQ

And that is all everybody!

If you feel this project is useful for you, please give my project a Github star ⭐ as an encouragement!

Thank you so much!

Microservices with Java Spring Boot

Linh Truong Cong Hong — Sat, 05 Feb 2022 15:04:06 +0000

Github repo for this project:

https://github.com/linhtch90/microservices-java-demo-zoo-devto

Introduction

Configuration server
Service discovery with Eureka
2 demo microservices called Tiger and Panther
Gateway server
RabbitMQ for messaging between microservices

The relationships between those services are described as the following figure.

Let's begin building this system!

Configuration server

Go to start.spring.io and generate a new project with the following information:

Group ID: com.microservices.zooconfsvr
Artifact ID: microservice-zoo-config-server
Name: microservice-zoo-config-server
Description: zoo microservices config server
JDK: I am using JDK 17 for this tutorial. I have not tested this project with older JDKs yet!
Dependencies: Config Server (So other services can get their configuration information from this service)

Your pom.xml should look like this:

<dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-bootstrap</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-config-server</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

In folder src/main/resources/, add a file called bootstrap.properties
In folder src/main/resources/, add a folder called config/ and create 4 configuration files eureka-server.properties, gateway-server.properties, panther-service.properties, tiger-service.properties
The content of those .properties files could be found in my Github repo I put the link on top of this blog post)

Add @EnableConfigServer annotation to the main entrance class MicroserviceZooConfigServerApplication.java.

Service discovery (with Eureka)

Go to start.spring.io and generate a new project with the following information:

Group ID: com.microservices.zooeurekasvr
Artifact ID: microservice-zoo-services-discovery
Name: microservice-zoo-services-discovery
Description: zoo microservices services discovery
Dependencies: Eureka server, config client

Your pom.xml should look like this:

<properties>
        <java.version>17</java.version>
        <spring-cloud.version>2021.0.0</spring-cloud.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-bootstrap</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-config</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-loadbalancer</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

In folder src/main/resources/, add a file called bootstrap.properties
The content of those .properties files could be found in my Github repo (I put the link on top of this blog post)

Add @EnableEurekaServer annotation to MicroserviceZooServicesDiscoveryApplication.java

Gateway server

Gateway server is the service that handles all request from client. Go to start.spring.io and generate a new project with the following information:

Group ID: com.microservices.zoogateway
Artifact ID: microservice-zoo-gateway
Name: microservice-zoo-gateway
Description: microservice gateway for the zoo demo
Dependencies: Eureka client, config client, gateway

Your pom.xml should look like this:

<properties>
        <java.version>17</java.version>
        <spring-cloud.version>2021.0.0</spring-cloud.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-bootstrap</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-config</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-gateway</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

In folder src/main/resources/, add a file called bootstrap.properties
The content of those .properties files could be found in my Github repo (I put the link on top of this blog post)

Add @EnableEurekaServer annotation to MicroserviceZooGatewayApplication.java

Tiger service

Go to start.spring.io and generate a new project with the following information:

Group ID: com.microservices.tigerservice
Artifact ID: microservice-tiger
Name: microservice-tiger
Description: microservice tiger
Dependencies: Eureka client, config client, web, client load balancer, open feign (also for load balancer), RabbitMQ

Your pom.xml should look like this:

<dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-bootstrap</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-loadbalancer</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.springframework.cloud/spring-cloud-starter-openfeign -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
            <version>3.1.0</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-config</artifactId>
        </dependency>
        <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-amqp</artifactId>
    </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

In folder src/main/resources/, add a file called bootstrap.properties
The content of those .properties files could be found in my Github repo (I put the link on top of this blog post)

Add @EnableFeignClients annotation to MicroserviceTigerApplication.java

Create com.microservices.tigerservice.service package and add 2 files ClientToPantherService.java for directly call Panther service and RabitMQSender.java for sending a string message to Panther via RabbitMQ.
Create com.microservices.tigerservice.controller package and add TigerController.java, specifying controllers for calling Panther service.
Create com.microservices.tigerservice.component package and add RabitMQSenderComponent.java for creating Beans related to messaging service.
Please refer to my Github repo for the content of these files.

Panther service

Go to start.spring.io and generate a new project with the following information:

Group ID: com.microservices.pantherservice
Artifact ID: microservice-panther
Name: microservice-panther
Description: microservice panther
Dependencies: Eureka client, config client, web, client load balancer, RabbitMQ

Your pom.xml should look like this:

<dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-bootstrap</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-loadbalancer</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-config</artifactId>
        </dependency>
        <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-amqp</artifactId>
    </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

In folder src/main/resources/, add a file called bootstrap.properties
The content of those .properties files could be found in my Github repo (I put the link on top of this blog post)

Create controller and other components for the services as follow.

Create com.microservices.pantherservice.controller package and add TigerCallPanther.java for directly respond to calls from Tiger service in the form of a string.
Create com.microservices.pantherservice.component package and add 2 files RabbitMQComponent.java and RabbitMQReceiver.java for settings related to listening and responding to messages sent from Tiger service. Right after receiving the message from Tiger service, Panther service print the message into the Log.
Please refer to my Github repo for the content of these files.

RabbitMQ

Please refer to this tutorial for using RabbitMQ with Docker.

Running the whole system

Please follow this order:

Start RabbitMQ with Docker (see above section)
Start Configuration server
Start Discovery service
Start Tiger service
Start Panther service
Start Gateway server

Testing microservices with Postman

Direct call from Tiger service to Panther service: Open Postman and send a request to

http://localhost:8074/tiger-service/tiger/callpantherservice

The result should look like the following figure.

Send message from Tiger service to Panther service: Open Postman and send a request to

http://localhost:8074/tiger-service/tiger/sendmessagetopanther

There is not any response in Postman. It is okay. Please go to the terminal screen where you are running Panther service. You will see a log message saying:

Received message is: Message from Tiger to Panther via RabbitMQ

And that is all everybody!

If you feel this project is useful for you, please give my project a Github star ⭐ as an encouragement!

Thank you so much!

Build a microservices system with Java

Linh Truong Cong Hong — Sat, 05 Feb 2022 11:47:12 +0000

Github repo for this project: (Please give me a Github star ⭐ for this effort! Thank you!)
https://github.com/linhtch90/microservices-java-demo-zoo-devto

Introduction

Configuration server
Service discovery with Eureka
2 demo microservices called Tiger and Panther
Gateway server
RabbitMQ for messaging between microservices

The relationships between those services are described as the following figure.

Let's begin building this system!

Configuration server

Go to start.spring.io and generate a new project with the following information:

Group ID: com.microservices.zooconfsvr
Artifact ID: microservice-zoo-config-server
Name: microservice-zoo-config-server
Description: zoo microservices config server
JDK: I am using JDK 17 for this tutorial. I have not tested this project with older JDKs yet!
Dependencies: Config Server (So other services can get their configuration information from this service)

Your pom.xml should look like this:

<dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-bootstrap</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-config-server</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

In folder src/main/resources/, add a file called bootstrap.properties
In folder src/main/resources/, add a folder called config/ and create 4 configuration files eureka-server.properties, gateway-server.properties, panther-service.properties, tiger-service.properties
The content of those .properties files could be found in my Github repo I put the link on top of this blog post)

Add @EnableConfigServer annotation to the main entrance class MicroserviceZooConfigServerApplication.java.

Service discovery (with Eureka)

Go to start.spring.io and generate a new project with the following information:

Group ID: com.microservices.zooeurekasvr
Artifact ID: microservice-zoo-services-discovery
Name: microservice-zoo-services-discovery
Description: zoo microservices services discovery
Dependencies: Eureka server, config client

Your pom.xml should look like this:

<properties>
        <java.version>17</java.version>
        <spring-cloud.version>2021.0.0</spring-cloud.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-bootstrap</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-config</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-loadbalancer</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

In folder src/main/resources/, add a file called bootstrap.properties
The content of those .properties files could be found in my Github repo (I put the link on top of this blog post)

Add @EnableEurekaServer annotation to MicroserviceZooServicesDiscoveryApplication.java

Gateway server

Gateway server is the service that handles all request from client. Go to start.spring.io and generate a new project with the following information:

Group ID: com.microservices.zoogateway
Artifact ID: microservice-zoo-gateway
Name: microservice-zoo-gateway
Description: microservice gateway for the zoo demo
Dependencies: Eureka client, config client, gateway

Your pom.xml should look like this:

<properties>
        <java.version>17</java.version>
        <spring-cloud.version>2021.0.0</spring-cloud.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-bootstrap</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-config</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-gateway</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

In folder src/main/resources/, add a file called bootstrap.properties
The content of those .properties files could be found in my Github repo (I put the link on top of this blog post)

Add @EnableEurekaServer annotation to MicroserviceZooGatewayApplication.java

Tiger service

Go to start.spring.io and generate a new project with the following information:

Group ID: com.microservices.tigerservice
Artifact ID: microservice-tiger
Name: microservice-tiger
Description: microservice tiger
Dependencies: Eureka client, config client, web, client load balancer, open feign (also for load balancer), RabbitMQ

Your pom.xml should look like this:

<dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-bootstrap</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-loadbalancer</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.springframework.cloud/spring-cloud-starter-openfeign -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
            <version>3.1.0</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-config</artifactId>
        </dependency>
        <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-amqp</artifactId>
    </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

In folder src/main/resources/, add a file called bootstrap.properties
The content of those .properties files could be found in my Github repo (I put the link on top of this blog post)

Add @EnableFeignClients annotation to MicroserviceTigerApplication.java

Create com.microservices.tigerservice.service package and add 2 files ClientToPantherService.java for directly call Panther service and RabitMQSender.java for sending a string message to Panther via RabbitMQ.
Create com.microservices.tigerservice.controller package and add TigerController.java, specifying controllers for calling Panther service.
Create com.microservices.tigerservice.component package and add RabitMQSenderComponent.java for creating Beans related to messaging service.
Please refer to my Github repo for the content of these files.

Panther service

Go to start.spring.io and generate a new project with the following information:

Group ID: com.microservices.pantherservice
Artifact ID: microservice-panther
Name: microservice-panther
Description: microservice panther
Dependencies: Eureka client, config client, web, client load balancer, RabbitMQ

Your pom.xml should look like this:

<dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-bootstrap</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-loadbalancer</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-config</artifactId>
        </dependency>
        <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-amqp</artifactId>
    </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

In folder src/main/resources/, add a file called bootstrap.properties
The content of those .properties files could be found in my Github repo (I put the link on top of this blog post)

Create controller and other components for the services as follow.

Create com.microservices.pantherservice.controller package and add TigerCallPanther.java for directly respond to calls from Tiger service in the form of a string.
Create com.microservices.pantherservice.component package and add 2 files RabbitMQComponent.java and RabbitMQReceiver.java for settings related to listening and responding to messages sent from Tiger service. Right after receiving the message from Tiger service, Panther service print the message into the Log.
Please refer to my Github repo for the content of these files.

RabbitMQ

Please refer to this tutorial for using RabbitMQ with Docker.

Running the whole system

Please follow this order:

Start RabbitMQ with Docker (see above section)
Start Configuration server
Start Discovery service
Start Tiger service
Start Panther service
Start Gateway server

Testing microservices with Postman

Direct call from Tiger service to Panther service: Open Postman and send a request to

http://localhost:8074/tiger-service/tiger/callpantherservice

The result should look like the following figure.

Send message from Tiger service to Panther service: Open Postman and send a request to

http://localhost:8074/tiger-service/tiger/sendmessagetopanther

There is not any response in Postman. It is okay. Please go to the terminal screen where you are running Panther service. You will see a log message saying:

Received message is: Message from Tiger to Panther via RabbitMQ

And that is all everybody!

If you feel this project is useful for you, please give my project a Github star ⭐ as an encouragement!

Thank you so much!

How to get start understanding source code of open source projects?

Linh Truong Cong Hong — Sat, 29 Jan 2022 09:33:57 +0000

Hello,

Open source software is awesome and important for the industry. However, whenever I try to read some code for an open source project with the intent to contribute, I get scared. I get this weird anxiety and for some reason my brain freezes. I can't understand anything what the code is doing and how it's working, it looks too complicated even if I kinda understand what things are supposed to do.

I can't describe the feeling. Even if I know the language and I've learned a lot.

How do I start?

Clone Twitter functions with ReactJS

Linh Truong Cong Hong — Wed, 26 Jan 2022 08:38:04 +0000

I have developed a small social network web app for educational purpose and want to share this with the community. This app is built with ReactJS for frontend, Java Spring Boot for backend and MongoDB as the database.

The app tries to mimic a few functions of Twitter, including:

Create post with text and image
The number of characters in each post is limited to 200 characters
Like, comment and re-post a post
View the number of likes, comments and shares of a post
Comments are toggle
The number of character in each comment is limited to 100 characters
Follow, un-follow someone
See who are following us and follow them back
Check who we are following
View all posts of an individual
View our own posts
List all user accounts in the entire social network (due to the number of users are still small, I did not develop search user function)

Other functions:

Due to limited storage space, client app compresses the uploaded image to the maximum of 250px (width or height) User avatar is created by hashing user id and convert that hash code into a hexagonal image
Authentication and authorization use JWT
Responsive frontend for desktop and mobile devices

Technical stack:

Frontend: ReactJS, Redux Toolkit, React Router, React Bootstrap
Backend: Java Spring Boot
Database: MongoDB

For source code and demo, please visit my Github repo:

https://github.com/linhtch90/psn-social-network-public-source

Please give me a ⭐ Github star ⭐ for my effort if you think this project is useful for you!

Develop a Twitter clone with ReactJS

Linh Truong Cong Hong — Fri, 21 Jan 2022 17:17:25 +0000

The app tries to mimic a few functions of Twitter, including:

Create post with text and image
The number of characters in each post is limited to 200 characters
Like, comment and re-post a post
View the number of likes, comments and shares of a post
Comments are toggle
The number of character in each comment is limited to 100 characters
Follow, un-follow someone
See who are following us and follow them back
Check who we are following
View all posts of an individual
View our own posts
List all user accounts in the entire social network (due to the number of users are still small, I did not develop search user function)

Other functions:

Due to limited storage space, client app compresses the uploaded image to the maximum of 250px (width or height) User avatar is created by hashing user id and convert that hash code into a hexagonal image
Authentication and authorization use JWT
Responsive frontend for desktop and mobile devices

Technical stack:

Frontend: ReactJS, Redux Toolkit, React Router, React Bootstrap
Backend: Java Spring Boot
Database: MongoDB

Please give me a ⭐ Github star ⭐ for my effort if you think this project is useful for you!

Live Demo and Source Code:

https://github.com/linhtch90/psn-social-network-public-source

Develope a twitter clone with ReactJS

Linh Truong Cong Hong — Tue, 18 Jan 2022 05:03:14 +0000

The app tries to mimic a few functions of Twitter, including:

Create post with text and image
The number of characters in each post is limited to 200 characters
Like, comment and re-post a post
View the number of likes, comments and shares of a post
Comments are toggle
The number of character in each comment is limited to 100 characters
Follow, un-follow someone
See who are following us and follow them back
Check who we are following
View all posts of an individual
View our own posts
List all user accounts in the entire social network (due to the number of users are still small, I did not develop search user function)

Other functions:

Due to limited storage space, client app compresses the uploaded image to the maximum of 250px (width or height) User avatar is created by hashing user id and convert that hash code into a hexagonal image
Authentication and authorization use JWT
Responsive frontend for desktop and mobile devices

Technical stack:

Frontend: ReactJS, Redux Toolkit, React Router, React Bootstrap
Backend: Java Spring Boot
Database: MongoDB

Hope you enjoy it and give me a ⭐ Github star ⭐ for my effort!

Live Demo and Source Code:

https://github.com/linhtch90/psn-social-network-public-source

Code a social network with ReactJS

Linh Truong Cong Hong — Mon, 17 Jan 2022 08:55:12 +0000

The app tries to mimic a few functions of Twitter, including:

Create post with text and image
The number of characters in each post is limited to 200 characters
Like, comment and re-post a post
View the number of likes, comments and shares of a post
Comments are toggle
The number of character in each comment is limited to 100 characters
Follow, un-follow someone
See who are following us and follow them back
Check who we are following
View all posts of an individual
View our own posts
List all user accounts in the entire social network (due to the number of users are still small, I did not develop search user function)

Other functions:

Due to limited storage space, client app compresses the uploaded image to the maximum of 250px (width or height) User avatar is created by hashing user id and convert that hash code into a hexagonal image
Authentication and authorization use JWT
Responsive frontend for desktop and mobile devices

Technical stack:

Frontend: ReactJS, Redux Toolkit, React Router, React Bootstrap
Backend: Java Spring Boot
Database: MongoDB

Hope you enjoy it and give me a ⭐ Github star ⭐ for my effort!

Live Demo:
https://psn-social-network.herokuapp.com/#/

Source Code:
https://github.com/linhtch90/psn-social-network-public-source

Build a social network app with ReactJS, Spring Boot and MongoDB

Linh Truong Cong Hong — Fri, 14 Jan 2022 02:07:30 +0000

The app tries to mimic a few functions of Twitter, including:

Create post with text and image
The number of characters in each post is limited to 200 characters
Like, comment and re-post a post
View the number of likes, comments and shares of a post
Comments are toggle
The number of character in each comment is limited to 100 characters
Follow, un-follow someone
See who are following us and follow them back
Check who we are following
View all posts of an individual
View our own posts
List all user accounts in the entire social network (due to the number of users are still small, I did not develop search user function)

Other functions:

Due to limited storage space, client app compresses the uploaded image to the maximum of 250px (width or height)
User avatar is created by hashing user id and convert that hash code into a hexagonal image
Authentication and authorization use JWT
Responsive frontend for desktop and mobile devices

Technical stack:

Frontend: ReactJS, Redux Toolkit, React Router, React Bootstrap
Backend: Java Spring Boot
Database: MongoDB

If this project is useful for you , please give me a Github star ⭐ for my effort!

Source Code:
https://github.com/linhtch90/psn-social-network-public-source

Live Demo:
https://psn-social-network.herokuapp.com/#/

How to build a social network app with ReactJS

Linh Truong Cong Hong — Thu, 13 Jan 2022 07:51:38 +0000

The app tries to mimic a few functions of Twitter, including:

Create post with text and image
The number of characters in each post is limited to 200 characters
Like, comment and re-post a post
View the number of likes, comments and shares of a post
Comments are toggle
The number of character in each comment is limited to 100 characters
Follow, un-follow someone
See who are following us and follow them back
Check who we are following
View all posts of an individual
View our own posts
List all user accounts in the entire social network (due to the number of users are still small, I did not develop search user function)

Other functions:

Due to limited storage space, client app compresses the uploaded image to the maximum of 250px (width or height)
User avatar is created by hashing user id and convert that hash code into a hexagonal image
Authentication and authorization use JWT
Responsive frontend for desktop and mobile devices

Technical stack:

Frontend: ReactJS, Redux Toolkit, React Router, React Bootstrap
Backend: Java Spring Boot
Database: MongoDB

If this project is useful for you , please give me a ⭐ Github star ⭐ for my effort!

Source Code:
https://github.com/linhtch90/psn-social-network-public-source

Develop a social network with ReactJS, Spring Boot and MongoDB

Linh Truong Cong Hong — Tue, 11 Jan 2022 02:31:53 +0000

The app tries to mimic a few functions of Twitter, including:

Create post with text and image
The number of characters in each post is limited to 200 characters
Like, comment and re-post a post
View the number of likes, comments and shares of a post
Comments are toggle
The number of character in each comment is limited to 100 characters
Follow, un-follow someone
See who are following us and follow them back
Check who we are following
View all posts of an individual
View our own posts
List all user accounts in the entire social network (due to the number of users are still small, I did not develop search user function)

Other functions:

Due to limited storage space, client app compresses the uploaded image to the maximum of 250px (width or height)
User avatar is created by hashing user id and convert that hash code into a hexagonal image
Authentication and authorization use JWT
Responsive frontend for desktop and mobile devices

Technical stack:

Frontend: ReactJS, Redux Toolkit, React Router, React Bootstrap
Backend: Java Spring Boot
Database: MongoDB

Hope you enjoy it and if this project is useful for you , please give me a ⭐ Github star ⭐ for my effort!

Source Code:
https://github.com/linhtch90/psn-social-network-public-source

Live Demo:
https://psn-social-network.herokuapp.com/#/

Example social network developed with ReactJS, Spring Boot and MongoDB

Linh Truong Cong Hong — Sun, 09 Jan 2022 16:02:56 +0000

The app tries to mimic a few functions of Twitter, including:

Create post with text and image
The number of characters in each post is limited to 200 characters
Like, comment and re-post a post
View the number of likes, comments and shares of a post
Comments are toggle
The number of character in each comment is limited to 100 characters
Follow, un-follow someone
See who are following us and follow them back
Check who we are following
View all posts of an individual
View our own posts
List all user accounts in the entire social network (due to the number of users are still small, I did not develop search user function)
Other functions:
- Due to limited storage space, client app compresses the uploaded image to the maximum of 250px (width or height) User avatar is created by hashing user id and convert that hash code into a hexagonal image
- Authentication and authorization use JWT
- Responsive frontend for desktop and mobile devices
Technical stack:
- Frontend: ReactJS, Redux Toolkit, React Router, React Bootstrap
- Backend: Java Spring Boot
- Database: MongoDB

Hope you enjoy it and if this project is useful for you , please give me a ⭐ Github star ⭐ for my effort!

Live Demo:
https://psn-social-network.herokuapp.com/#/

Source Code:
https://github.com/linhtch90/psn-social-network-public-source