microservices-demo

This project is to demonstrate the Microservice Architecture, so here I have included two Microservices which are forex based.

We have here Zuul API Gateway which is the proxy for our microservices, and it takes care of the load balancing and forwards the request accordingly to the particular service.

We have here Eureka Server which registers the Services and Zuul API Gateway.

This is a high-level overview of what I have built, and the detailed information for all the components available below.

Requirements To Run Applications

• Git (Optional)
• JDK 8 or later
• IDE

Dependencies And Tools Used To Build Applications

• Git
• JDK 8 or later
• Gradle 6.3
• Spring Boot Web
• Spring Boot Data JPA
• H2 Database
• Lombok
• IDE
• Eureka Client
• Eureka Server
• Zuul Proxy
• Hystrix
• Feign

Eureka Server

Eureka Server is an application that holds information about all client-service applications.

Every Microservice will register into the Eureka server and the Eureka server knows all the client applications running on each port and IP address.

Eureka Server is also known as Discovery Server.

To Run "eureka-server"

1. Go to the /microservices-demo/eureka-server directory and open terminal

2. Execute the following command in the terminal

   gradlew bootrun 
   

And now we can access the Eureka Server on this link: Eureka Server

You will see here registered Services and Zuul API Gateway once we start them.

forex-rates-service

It provides exchange rates for the different currencies, for example, if I want to know the rate USD to INR, EUR to INR, or AUD to INR so this service will provide the exchange rate. The response will be like the following.

{
    "id": 1,
    "from": "USD",
    "to": "INR",
    "rate": 75.56,
    "port": 8001
}

{
    "id": 2,
    "from": "EUR",
    "to": "INR",
    "rate": 81.65,
    "port": 8001
}

{
    "id": 3,
    "from": "AUD",
    "to": "INR",
    "rate": 48.60,
    "port": 8001
}

Once you start this service these records will be available by default, and it will be stored in memory in the H2 database.

To Start "forex-rates-service"

1. Go to the /microservices-demo/forex-rates-service directory and open terminal

2. Execute the following command in the terminal

   gradlew bootrun 
   

At this point you are might thinking that what are the APIs we can use to access this service. But don't worry we will talk about the APIs in the Zuul API Gateway section.

forex-converter-service

This service basically converts a particular amount to another currency let's say I have 5 dollars and I want to convert it to the Indian rupees so for that purpose, we can use this service. Here the response sample we get from this service.

{
    "id": 1,
    "from": "USD",
    "to": "INR",
    "rate": 75.56,
    "amount": 5,
    "convertedAmount": 377.80,
    "port": 9001
}

In the above example, we are converting 5 dollars to the Indian rupees and it is giving us the converted amount.Guess what we are taking conversion rate from forex-rates-service and then in this service, we are multiplying the rate with the given amount.

For the communication between services we are using Feign here, so it takes care to call instances dynamically and balance the load accordingly.

This service calls the forex-rates-service so in order to make this service fault-tolerant and resilient we have implemented the Hystrix mechanism.

To Start "forex-converter-service"

1. Go to the /microservices-demo/forex-converter-service directory and open terminal

2. Execute the following command in the terminal

   gradlew bootrun 
   

Zuul API Gateway

Zuul Server is an API Gateway application. It handles all the requests and performs the dynamic routing of microservice applications. It works as a front door for all the requests. It is also known as Edge Server.

Zuul is built to enable dynamic routing, monitoring, resiliency, and security. Here we are covering dynamic routing and resiliency.

We have implemented Hystrix to make our gateway resilient, so we have a fallback mechanism here, in case the services are not available, so the user can get a nice readable message instead of nasty errors.

To Start "zuul-gateway-service"

1. Go to the /microservices-demo/zuul-gateway-service directory and open terminal

2. Execute the following command in the terminal

   gradlew bootrun 
   

And now we can access the services through this gateway. I request you to start multiple instances of the forex-rates-service and forex-converter-service. So you can see that the requests are forwarding to the multiple instances to balance the load.

List of APIs To Access "forex-rates-service"

• USD to INR
• EUR to INR
• AUD to INR

List of APIs To Access "forex-converter-service"

• USD to INR
• EUR to INR
• AUD to INR