cr21 / EWallet

EWallet Web Services. Developed multiple web services like user service, wallet service, notification service, email service using Spring Boot, Apache Kafka, Redis.

EWallet

Requirements and Goals of the System

We will design the system with following requirement and design choice. We will use Spring Boot, Redis, Apache Kafka, MySQL.

We will build following web service

1. User Service - We will create a user who will use our payment service.
2. Wallet Service - For each user we will create a wallet, through wallet user can send and receive money.
3. Transaction Service - When user transfer money to different user Wallet should be updated for successful transaction.
4. Notification Service - Send notification for wallet update, transaction update.

Communication between different service

We will use Apache Kafka messaging for communicating between different service.

1. When User is created we will produce message on "USER_CREATE" topic on kafka cluster.
2. We will configure Wallet Service to listen( consume) on "USER_CREATE" topic, so whenever user is created, wallet service will get message from topic and create a new wallet, after wallet is created Wallet Service will produce message on "WALLET_CREATE" topic.
3. We will configure Notification Service to listen on "WALLET_CREATE" topic, so whenever wallet is created for user, email service will send email to user.
4. Transaction Service will create a transaction when user wants to transfer amount to other user. Transaction service will produce message on "TRANSACTION_CREATE" topic.
5. We will configure Wallet Service to listen on "TRANSACTION_CREATE" topic, so whenever user make any transaction, wallet service will get message from topic and wallet service will process transaction, validate transaction and update transaction status.
6. After processing transaction Wallet Service will produce message on "WALLET_UPDATE" topic. We will configure Notification Service to listen on "WALLET_UPDATE" topic, so whenever wallet is updated for user, notification service will send email to user with updated balance.
7. After processing transaction, Wallet Service will produce message on "TRANSACTION_COMPLETE" topic with updated transaction status, We will configure Notification Service to listen on "TRANSACTION_COMPLETE" topic, so whenever transaction is updated for user, notification service will send email to user with transaction status.
8. We will also configure Redis for caching

Apache Kafka Message Flow

Project Requirements

1. Install redis - brew install redis
2. Install kafka - brew install kafka
3. Start Zookeeper - Go to [KAFKA_INSTALL_DIR] and run sh /bin/zookeeper-server-start.sh config/zookeeper.properties
4. Start Kafka server - Go to [KAFKA_INSTALL_DIR] and run sh bin/kafka-server-start.sh config/server.properties

To see messages produced by Kafka, run following command

sh bin/kafka-console-consumer.sh --bootstrap-server localhost:9092 --topic "USER_CREATE"