https://github.com/mploed/event-driven-spring-boot

Example Application to demo various flavours of handling domain events in Spring Boot
https://github.com/mploed/event-driven-spring-boot

atom event-driven event-sourcing events feed rest-api spring spring-boot spring-cloud-stream spring-data-jpa

Last synced: 6 days ago
JSON representation

Example Application to demo various flavours of handling domain events in Spring Boot

• Host: GitHub
• URL: https://github.com/mploed/event-driven-spring-boot
• Owner: mploed
• License: apache-2.0
• Created: 2017-05-18T12:10:05.000Z (over 7 years ago)
• Default Branch: master
• Last Pushed: 2018-09-24T08:53:12.000Z (over 6 years ago)
• Last Synced: 2025-01-08T15:17:44.116Z (13 days ago)
• Topics: atom, event-driven, event-sourcing, events, feed, rest-api, spring, spring-boot, spring-cloud-stream, spring-data-jpa
• Language: Java
• Homepage:
• Size: 409 KB
• Stars: 265
• Watchers: 32
• Forks: 123
• Open Issues: 2
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Awesome Lists containing this project

README

        
# Event Driven Applications with Spring Boot

This projects tries to capture various options you have when dealing with Event Driven Spring Boot applications.

The follwing Spring Technologies are being used:

- Spring Boot

- Spring Cloud Stream Rabbit

- Spring Data JPA

These examples contain various different ways to model and deal with events:

- Complete aggregates / entities in the events

- REST Resource URLs in events

- Partial parsing / handling of events in consumers

- Events as Atom Feeds

## Prerequisites

- You need to have Docker installed

## How to run and install the example

In the root directory you need to

1. Compile everything with ./mvnw package

2. Start everything up with docker-compose up --build

## Running on Kubernetes

Mind the KubernetesSetup.md file in the kubernetes directory

## URLs and Ports

Each of the modules is it's own Spring Boot Application which can be accessed as follows:

    

        Name

        Application / Enpoint Type

        URL

    

    

        Application Process

        9000

        http://localhost:9000

    

    

        Credit Application

        9001

        http://localhost:9001/credit-application

    

    

        Customer

        9002

        http://localhost:9002/customer and http://localhost:9002/customer/feed

    

    

        Scoring

        9003

        No UI

    

     

        CreditDecision

        9004

        http://localhost:9004/credit-decision and http://localhost:9004/credit-decision/feed

    

      

    

## Messaging Infrastructure & Domain Events

### Public Events

#### CreditApplicationNumberGeneratedEvent

Source: application-process

Persisted in source: no

Consumers:

- credit-application

- credit-decision

Topic: CreditApplicationNumberGeneratedTopic

#### CreditApplicationEnteredEvent

Source: credit-application

Persisted in source: yes in its own Table via JPA

Consumers:

- application-process

- credit-decision

Topic: CreditApplicationEnteredTopic

#### CustomerCreatedEvent

Source: customer

Persisted in source: no

Consumers:

- application-process

- credit-decision

Topic: CustomerCreatedTopic

#### ScoringPositiveEvent

Source: scoring

Persisted in source: no

Consumers:

- application-process

- credit-decision

Topic: ScoringPositiveTopic

#### ScoringNegativeEvent

Source: scoring

Persisted in source: no

Consumers:

- application-process

- credit-decision

Topic: ScoringNegativeTopic

#### ApplicationDeclinedEvent

Source: credit-decision

Persisted in source: not as an event

Consumers:

- application-process

Topic: ApplicationDeclinedTopic

### Internal Events

#### Credit-Application

- CreditDetailsEnteredEvent

- FinancialSituationEnteredEvent

Both events are stored

Source: credit-application

Storage: Own Table via JPA

### Feeds

#### Customer Feed

Url: http://localhost:9002/customer/feed

Contains URLs to Customer Resources

#### Credit Decision Feed

Url: http://localhost:9004/credit-decision/feed

Contains Application Numbers that have been confirmed

## Event Types being used

This demo shows various types of event types: Events with all the data, Events with Resource Urls and "Events" as Feeds

#### Events with all the data

Especially the CreditApplicationEnteredEvent falls into this category: it contains all of the data for the credit application

such as the financial situation and the details of the actual credit. By consuming this event you will not need additional

roundtrips to upstream systems

Other events that fall into this category are:

- ApplicationNumberGeneratedEvent

- ScoringNegativeEvent

- ScoringPositiveEvent

- ApplicationDeclinedEvent

##### Idea of Bounded Context:

Please take a close look at how the CreditApplicationEnteredEvent is being reflected in the scoring application. Yes, we

take in all the payload from the broker but the public model of the event has a clear focus on the scoring context's view 

  on the data.

#### Events with a Resource URL

These Events do not contain a lot of information. They may contian something like a business process identifier such as

the applicationNumber in this example but for the purpose of this demo I refrained from doing that. So the CustomerCreatedEvent

only contians the URL to the Customer REST Resource from which interested contexts can obtain the payload from.

#### "Events" via Feeds

Althoug the usage of feeds is no plain and pure event driven processing style I think that they come in handy when you

are dealing with situations like these:

- you have issues with your message broker and firewalls and these issues can't be resolved easily

- you need to have an event replay functionality in place that enables consumers to restore their replicated data

You can find "Events via Feeds" in the customer and the credit-decision (see Feeds) applications.