Bank Account Service

Daniel Machado Vasconcelos

Basic requirements (that were implemented):

• Expose endpoints to create and close a bank account;
• Expose endpoints to deposit and withdraw founds;
• The service must make use of event source and CQRS;
• The service must persist aggregate state of all bank accounts;

Extra requirements to be done:

• Add security layer to permit only authenticated users to operate;
• Add swagger documentation to the Rest API;
• Make sure all exchanged messages are encrypted, authenticated and has schema.

---

Prerequisites

• Java JDK 17
• Maven
• Docker / Docker Compose

Resources

• Kafka
• Postgres
• Elasticsearch

Tech Stack usage

Kafka

I used kafka as my main message broker, to communicate between other services components, that are interested in the events.

Postgres

This resource saves the aggregate state of my bank account. The service reduce the list of events to a single bank account database row.

Elasticsearch

This database saves the list of events in order, ensured by an optimistic lock.

How to build?

Clone this repo into new project folder (e.g., bank-account-service).

git clone https://github.com/DanielMachadoVasconcelos/bank-account.git
cd bank-account-service

Start the external resources by running the docker-compose file. (It may take a while to start all resources)

docker-compose up -d 

---

Start individually the spring boot applications (command and query)

Start the service (command) that expose the REST API:

cd command
mvn spring-boot:run

Use the following commands to open, deposit, withdraw and close a bank account:

To open a bank account

curl --location --request POST 'localhost:5000/api/v1/bank-accounts' \
--header 'Content-Type: application/json' \
--data-raw '{
    "account_holder":"daniel.vasconcelos",
    "account_type": "SAVINGS",
    "opening_balance": 45.0
}'

To deposit funds to bank account

curl --location --request POST 'localhost:5000/api/v1/bank-accounts/{bank-account-id}/deposits' \
--header 'Content-Type: application/json' \
--data-raw '{
    "amount": 12
}'

To withdraw funds from a bank account

curl --location --request POST 'localhost:5000/api/v1/bank-accounts/{bank-account-id}/withdraws' \
--header 'Content-Type: application/json' \
--data-raw '{
    "amount": 7.45
}'

To close a bank account

curl --location --request POST 'localhost:5000/api/v1/bank-accounts/6a21d2c6-a7e9-42ee-a584-86dcc331aafc/close' \
--header 'Content-Type: application/json' \
--data-raw '{
}'

---

Start the service (query) that will aggregate the bank account events:

cd query
mvn spring-boot:run

Postgres

• Access the local url (localhost:5050) in your favorite browser to verify the Postgres Database

Use the following credentials:

username	password
admin@admin.com	admin

Kibana

• Access the local url (localhost:5601) in your favorite browser to verify the Elasticsearch Database

No credentials are needed:

• Find the option 'Dev Tools' on the left menu
• Type the following command in the console:

 GET event-store/_search