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Kafka config & Implementation

Example of Existing Consumer (Java)

The below code snippet taken from cps-temporal can be used in the same way in NCMP to listen to message from DMI substituting the topics and errorHandler

Code Block
languagejava
titleExample Listener (Java, cps-temporal)
collapsetrue
 /**
     * Consume the specified event.
     *
     * @param cpsDataUpdatedEvent the data updated event to be consumed and persisted.
     */
    @KafkaListener(topics = "${app.listener.data-updated.topic}", errorHandler = "dataUpdatedEventListenerErrorHandler")
    public void consume(final CpsDataUpdatedEvent cpsDataUpdatedEvent) {

        log.debug("Receiving {} ...", cpsDataUpdatedEvent);

        // Validate event envelop
        validateEventEnvelop(cpsDataUpdatedEvent);

        // Map event to entity
        final var networkData = this.cpsDataUpdatedEventMapper.eventToEntity(cpsDataUpdatedEvent);
        log.debug("Persisting {} ...", networkData);

        // Persist entity
        final var persistedNetworkData = this.networkDataService.addNetworkData(networkData);
        log.debug("Persisted {}", persistedNetworkData);

    }


Example of Existing Consumer (Config)

Code Block
languageyml
titleExample of Existing Consumer (Config)
collapsetrue
# ============LICENSE_START=======================================================
# Copyright (c) 2021 Bell Canada.
# ================================================================================
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#       http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ============LICENSE_END=========================================================

# Spring profile configuration for sasl ssl Kafka

spring:
    kafka:
        bootstrap-servers: ${KAFKA_BOOTSTRAP_SERVER}
        security:
            protocol: SASL_SSL
        ssl:
            trust-store-type: JKS
            trust-store-location: ${KAFKA_SSL_TRUST_STORE_LOCATION}
            trust-store-password: ${KAFKA_SSL_TRUST_STORE_PASSWORD}
        properties:
            sasl.mechanism: SCRAM-SHA-512
            sasl.jaas.config: ${KAFKA_SASL_JAAS_CONFIG}
            ssl.endpoint.identification.algorithm:


Example of Existing Producer (Java)


Example of Existing Producer (Config)


Example of Kafka Docker-Compose


Code Block
languageyml
titleKafka Docker Example
collapsetrue
  kafka:
    image: confluentinc/cp-kafka:6.1.1
    container_name: kafka
    ports:
      - "19092:19092"
    depends_on:
      - zookeeper
    environment:
      KAFKA_BROKER_ID: 1
      KAFKA_ZOOKEEPER_CONNECT: zookeeper:2181
      KAFKA_ADVERTISED_LISTENERS: PLAINTEXT://kafka:9092,CONNECTIONS_FROM_HOST://localhost:19092
      KAFKA_LISTENER_SECURITY_PROTOCOL_MAP: PLAINTEXT:PLAINTEXT,CONNECTIONS_FROM_HOST:PLAINTEXT
      KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR: 1

...

Will we be able to handle everything "as-is"?


Future (or alternative)

What are Futures?



CompletableFuture (Java8+)

Java 8 introduced the the CompletableFuture class class. Along with the Future interface, it also implemented the CompletionStage interface. This interface defines the contract for an asynchronous computation step that we can combine with other steps.

CompletableFuture is at the same time a building block and a framework, with about 50 different methods for composing, combining, and executing asynchronous computation steps and handling errors.


Code Block
languagejava
themeEclipse
titleSimple Future Example
collapsetrue
public Future<String> calculateAsync() throws InterruptedException {
    CompletableFuture<String> completableFuture = new CompletableFuture<>();

    Executors.newCachedThreadPool().submit(() -> {
        Thread.sleep(500);
        completableFuture.complete("Hello");
        return null;
    });

    return completableFuture;
}

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