Spring Food Delivery Microservices (Spring Kafka + Confluent)

• Each service (restaurantservice, orderservice, notificationservice) has:
  • Spring Boot application class
  • spring-kafka integration and a KafkaConfig that supports Confluent Cloud (SASL/SSL) and optional Schema Registry (Avro)
  • Kafka handler classes that use KafkaTemplate<String, Object> and accept Object payloads (schema optional)
• orderservice includes a small REST endpoint POST /orders that publishes an OrderDto to the order-created topic so you can test the pipeline easily.
• pom.xml files were updated to include optional Confluent dependencies (kafka-avro-serializer, kafka-schema-registry-client) and the Confluent Maven repository (placeholders kept).

How Confluent integration is wired (placeholders)

• The services read the following properties from src/main/resources/application.properties:

  • spring.kafka.bootstrap-servers (e.g. pkc-xxxxx.confluent.cloud:9092)
  • spring.kafka.properties.security.protocol (set to SASL_SSL for Confluent Cloud)
  • spring.kafka.properties.sasl.mechanism (set to PLAIN)
  • spring.kafka.properties.sasl.jaas.config (example pattern below)

• Optional Schema Registry (Avro) settings (if you want Avro + Schema Registry):

  • schema.registry.url (e.g. https://<SR_HOST>)
  • schema.registry.basic.auth.credentials.source (usually USER_INFO)
  • schema.registry.basic.auth.user.info (e.g. <SR_API_KEY>:<SR_API_SECRET>)

How schema-optional behavior works in the code

• KafkaConfig will configure producers/consumers with String serializer/deserializer by default.
• If schema.registry.url is set, KafkaConfig will switch producer/consumer value serializer/deserializer to Confluent's Avro (KafkaAvroSerializer/KafkaAvroDeserializer) and set the schema registry URL and auth properties.
• Kafka templates and listener container factories are built with Object-typed values to allow either String payloads or Avro objects.
• Handlers in each service accept Object and use KafkaTemplate<String, Object>.

Where to put your Confluent credentials

• Option A (file): Edit the application.properties in each service and replace the <API_KEY>, <API_SECRET>, and schema registry placeholders.
• Option B (env vars): Run the service with system properties or environment variable expansion (recommended in production).

Windows (cmd.exe) build & run commands

• Build a single service (from the service directory):

cd \spring-food-delivery-microservices\orderservice
mvnw.cmd -DskipTests package

• Run the packaged JAR (from the service directory):

cd \spring-food-delivery-microservices\orderservice\target
java -jar orderservice-0.0.1-SNAPSHOT.jar

• Or run with Maven in-place (useful during development):

cd \spring-food-delivery-microservices\orderservice
mvnw.cmd spring-boot:run

Sample application.properties snippets (placeholders)

• In orderservice/src/main/resources/application.properties (already present):

spring.kafka.bootstrap-servers=localhost:9092
spring.kafka.properties.security.protocol=SASL_SSL
spring.kafka.properties.sasl.mechanism=PLAIN
spring.kafka.properties.sasl.jaas.config=org.apache.kafka.common.security.plain.PlainLoginModule required username="<API_KEY>" password="<API_SECRET>";

# Optional schema registry
schema.registry.url=https://<SCHEMA_REGISTRY_URL>
schema.registry.basic.auth.credentials.source=USER_INFO
schema.registry.basic.auth.user.info=<SR_API_KEY>:<SR_API_SECRET>

Quick test (creates an order and publishes to Kafka)

• Start your Kafka stack (local Kafka or set Confluent Cloud credentials). Then run the orderservice and execute:

curl -X POST -H "Content-Type: application/json" -d "{"orderId":"o-1","restaurantId":"r-1","items":"burger,fries","totalCents":1599}" http://localhost:8081/orders