Sample Credit Card application eco-system

This branch contains the demo with Spring Cloud Netflix Eureka. To see the same demo with other service registries, see the other branches.

After running all the apps execute POST at localhost:9080/application passing cardApplication.json as body.

http POST localhost:9080/application < cardApplication.json

• new card applications registered via card-service
• user registered via user-service
• fraud-service called by card-service and user-service to verify card applications and new users

+-------+                         +-------------+       +-------------+          +-------+             +---------------+  +-------+
| User  |                         | CardService |       | UserService |          | Proxy |             | FraudVerifier |  | Proxy |
+-------+                         +-------------+       +-------------+          +-------+             +---------------+  +-------+
    |                                    |                     |                     |                         |              |
    | Register application               |                     |                     |                         |              |
    |----------------------------------->|                     |                     |                         |              |
    |                                    |                     |                     |                         |              |
    |                                    | Create new user     |                     |                         |              |
    |                                    |------------------------------------------>|                         |              |
    |                                    |                     |                     |                         |              |
    |                                    |                     |     Create new user |                         |              |
    |                                    |                     |<--------------------|                         |              |
    |                                    |                     |                     |                         |              |
    |                                    |                     | Verify new user     |                         |              |
    |                                    |                     |-------------------->|                         |              |
    |                                    |                     |                     |                         |              |
    |                                    |                     |                     | Verify new user         |              |
    |                                    |                     |                     |------------------------>|              |
    |                                    |                     |                     |                         |              |
    |                                    |                     |                     |           User verified |              |
    |                                    |                     |                     |<------------------------|              |
    |                                    |                     |                     |                         |              |
    |                                    |                     |       User verified |                         |              |
    |                                    |                     |<--------------------|                         |              |
    |                                    |                     |                     |                         |              |
    |                                    |        User created |                     |                         |              |
    |                                    |<--------------------|                     |                         |              |
    |                                    |                     |                     |                         |              |
    |                                    |                     |                     |                         | User created |
    |                                    |<-----------------------------------------------------------------------------------|
    |                                    |                     |                     |                         |              |
    |                                    | Verify card application                   |                         |              |
    |                                    |-------------------------------------------------------------------->|              |
    |                                    |                     |                     |                         |              |
    |                                    |                     |                     Card application verified |              |
    |                                    |<--------------------------------------------------------------------|              |
    |                                    |                     |                     |                         |              |
    |        Card application registered |                     |                     |                         |              |
    |<-----------------------------------|                     |                     |                         |              |
    |                                    |                     |                     |                         |              |

Setup using new stack

Client side load-balancing using LoadBalancerClient

• @LoadBalanced RestTemplate uses Spring Cloud LoadBalancer under the hood

Apps communicating via Gateway:

• Routes have to be explicitly defined
• Possibility to configure routes either via properties or Java configuration
• All headers passed by default
• Routes matched using predicates, requests modified using filters

Spring Cloud Circuit Breaker + Resilience4J

• Interactions defined using injected CircuitBreakerFactory via the create() method
• HTTP call and fallback method defined
• Circuit breaker configuration modified in Customizer<CircuitBreaker bean in a @Configuration class
• Resilience4J used underneath

Centralised configuration with Spring Cloud ConfigServer

• card-service connects to ConfigServer to retrieve property values
• ConfigServer backed by a git repository
• Updating property values in a running application by using @RefreshScope beans and /actuator/refresh endpoint

Micrometer + Prometheus

• HTTP traffic monitoring using Micrometer + Prometheus
• Added a Micrometer's Timer to VerificationServiceClient