Sentiment Analysis example - without metrics

sentiment.analysis.service.ts

let senService: SentimentAnalysisService = new SentimentAnalysisService();
while (true) {
    let tweetInformation = kafkaConsumer.consume()
    let deserializedTweet: { msg: string } = deSerialize(tweetInformation)
    let sentimentResult = senService.calculateSentiment(deserializedTweet.msg)
    let seriarliedSentimentResult = serialize(sentimentResult)
    sentimentStore.store(sentimentResult);
    kafkaProducer.produce(seriarliedSentimentResult, 'sentiment_topic', 0);
}

sentiment.analysis.types.ts

enum SentimentStatus { Happy, Sad, Netural }
interface SentimentResult {
    sentiment: SentimentStatus
    confidence: number
}
interface SentimentAnalysis {
    calculateSentiment(str: String): SentimentResult
}
interface KafkaConsumer {
    consume(): string
}
interface KafkaProducer {
    produce(msg: string, topic: string, partition: number): boolean
}
interface SentimentStore {
    store(sentimentResult: SentimentResult): boolean
}

class SentimentAnalysisService implements SentimentAnalysis {
    calculateSentiment(str: String): SentimentResult {
        if (str.indexOf(":)") !== -1) {
            return { sentiment: SentimentStatus.Happy, confidence: 1 }
        } else if (str.indexOf(":(") !== -1) {
            return { sentiment: SentimentStatus.Sad, confidence: 1 }
        } else return { sentiment: SentimentStatus.Netural, confidence: 1 }
    }
}

let kafkaProducer: KafkaProducer = {
    produce(msg: string, topic: string, partition: number): boolean {
        console.info(`producing ${msg} to ${topic} in ${partition}`);
        return true;
    }
}

let sentimentStore: SentimentStore = {
    store(sentimentResult: SentimentResult): boolean {
        console.info(`storing ${JSON.stringify(sentimentResult)} to db`);
        return true;
    }
}

var count: number = 1

let kafkaConsumer: KafkaConsumer = {
    consume(): string {
        if (count % 2 == 0) {
            count++;
            return `{"msg": "I'm sad ${count} :("}`
        } else {
            count++;
            return `{"msg":"I'm happy ${count} :)"}`;
        }
    }
}

function deSerialize(str: string): any {
    return JSON.parse(str);
}

function serialize(str: any): string {
    return JSON.stringify(str)
}