Loan application DEMO - Java - Event Sourced

Not supported by Lightbend in any conceivable way, not open for contributions.

Prerequisite

• Java 11 or later
  
• Apache Maven 3.6 or higher
  
• Kalix:
  • Register account: Register
  • kalix tool installed: Kalix CLI
  • kalix login
  • project demo created and set for kalix
• Docker 20.10.8 or higher (engine and client)
  
• Docker Hub account (configured with Docker)
  Access to the gcr.io/kalix-public container registry
  cURL
  IDE / editor
  

Generate Java project (terminal)

mvn archetype:generate \
-DarchetypeGroupId=io.kalix \
-DarchetypeArtifactId=kalix-maven-archetype \
-DarchetypeVersion=LATEST

Define value for property 'groupId': com.example
Define value for property 'artifactId': loan-application
Define value for property 'version' 1.0-SNAPSHOT: :
Define value for property 'package' com.example: : com.example.loanapp

Import in IDE

Cleanup (IDE)

Delete:
src/main/proto/com/example/loanapp/counter_api.proto
src/main/proto/com/example/loanapp/domain/counter_domain.proto

API descriptor - endpoints (IDE)

Note: For code snippet insertion use command+J (MAC)

1. Create file loan_app_api.proto in src/main/proto/com/example/loanapp folder.
   
2. Edit src/main/proto/com/example/loanapp/loan_app_api.proto in IDE
   
3. Insert header snippet: aheader
4. Insert commands snippet: acmd
5. Insert state snippet: astate
6. Insert service snippet: asrv
7. Add functions to service snippet (place cursor inside brackets service LoanAppService { }): afunc

API descriptor - domain (IDE)

1. Create file loan_app_domain.proto in src/main/proto/com/example/loanapp/domain folder.
   
2. Edit src/main/proto/com/example/loanapp/domain/loan_app_domain.proto in IDE
   
3. Insert header snippet: dheader
4. Insert events snippet: devts
5. Insert state snippet: dstate

API descriptor - codegen annotations (IDE)

1. Edit src/main/proto/com/example/loanapp/loan_app_api.proto
2. Insert codegen annotations (place cursor under service LoanAppService { ): acodegen

Codegen

1. Code generation (terminal):

mvn compile

2. Refresh project (IDE)
3. Trigger Maven sync (IDE)

Business logic implementation (IDE)

1. Edit src/main/java/com/example/loanapp/domain/LoanAppEntity class
2. Delete class body
3. Insert code snippet (delete everything under constructor): eall

Implement unit test

1. Edit src/test/java/com/example/loanapp/domain/LoanAppEntityTest class
2. Delete class body
3. Insert code snippet: ut

Run unit test (terminal)

mvn test

Implement integration test (IDE)

1. Edit src/it/java/com/example/loanapp/LoanAppEntityIntegrationTest class
2. Delete everything under the constructor
3. Insert code snippet: it

Run integration test (terminal)

mvn -Pit verify

Run locally

??

Package & Deploy

1. Edit pom.xml and update my-docker-repo in <dockerImage>my-docker-repo/${project.artifactId}</dockerImage>
2. Execute in terminal:

mvn deploy

3. Expose service:

kalix services expose loan-application

Service 'loan-application' was successfully exposed at: mute-fog-6388.us-east1.kalix.app

Note: mute-fog-6388.us-east1.kalix.app is dedicated hostname for this service and is publicly accessible on Internet

Test service in production

1. Submit loan application

curl -XPOST -d '{
  "client_id": "1111",
  "client_monthly_income_cents": 60000,
  "loan_amount_cents": 20000,
  "loan_duration_months": 12
}' https://mute-fog-6388.us-east1.kalix.app/loanapp/123456 -H "Content-Type: application/json"

2. Get loan application:

curl -XGET https://mute-fog-6388.us-east1.kalix.app/loanapp/123456 -H "Content-Type: application/json"

2. Approve:

curl -XPUT https://mute-fog-6388.us-east1.kalix.app/loanapp/123456/approve -H "Content-Type: application/json"

Eventing (optional)

1. Create file loan_app_topic.proto in src/main/proto/com/example/loanapp folder.
   

2. Edit src/main/proto/com/example/loanapp/loan_app_topic.proto in IDE
   

3. Insert header snippet: dheader

4. Insert events snippet: devts

5. Insert service snippet: dsrv

6. Insert functions snippet (place cursor inside brackets service LoanAppToTopic { }): dfunc

7. Code generation (terminal):

mvn compile

9. Refresh project (IDE)
10. Trigger Maven sync (IDE)
11. Edit src/main/java/com/example/loanapp/LoanAppToTopicAction class
12. Delete class body
13. Insert code snippet: tall

Copy-paste list

mvn archetype:generate \
-DarchetypeGroupId=io.kalix \
-DarchetypeArtifactId=kalix-maven-archetype \
-DarchetypeVersion=LATEST

com.example

loan-application

com.example.loanapp

loan_app_api.proto

loan_app_domain.proto

mvn compile

mvn test

mvn -Pit verify

mvn deploy

curl -XPOST -d '{
  "client_id": "1111",
  "client_monthly_income_cents": 60000,
  "loan_amount_cents": 20000,
  "loan_duration_months": 12
}' https://mute-fog-6388.us-east1.kalix.app/loanapp/1 -H "Content-Type: application/json"

curl -XGET https://mute-fog-6388.us-east1.kalix.app/loanapp/1 -H "Content-Type: application/json"

curl -XPUT https://mute-fog-6388.us-east1.kalix.app/loanapp/1/approve -H "Content-Type: application/json"

loan_app_topic.proto