Hello enthusiasts,

Today we are going to learn about Fluvio work with this technology. This post is not about theory it’s a practical based article. You can checkout Fluvio’s own blogs to learn about fluvio deep.

Why to read this article?

Yes, you can find the documentation about Fluvio in the corners of internet but you can’t get a end-to-end project that’s what this article provides you. Believe me at the end you will find yourself confident with fluvio and one simple yet complex project. Let’s dive right in!

What is the Problem and the fix?

The problem is to solve the Real-time data stream of the price of stocks efficiently without using complex services like Kafka, Pulsar, Flink, Spark, etc. By using a simple topic-based data stream with Fluvio.

Create Project

I am going to use the following stack:

Frontend (Next.js)
Backend (Express.js)
Data Stream (Fluvio)

Let’s go step-by-step

Step 1: Install fluvio

Use To fluvio we need to install Fluvio CLI. We need a Docker or linux machine to install Fluvio. I will use WSL. To install fluvio run:

curl -fsS https://hub.infinyon.cloud/install/install.sh | bash

For Docker follow official fluvio steps.

Now you need to start the fluvio cluster

fluvio cluster start

If you need to start it a second time use this command:

fluvio cluster resume

Step 2: Set up project folder and file structure.

Create a folder and open it in VSCode (you can use anything).

├── server/
│   ├── index.ts           # Main server code
├── client/
│   ├── components/
│   │   │
│   │   ├── StockChart.tsx  # Main chart component
│   │   └── StockSwitch.tsx  # Component for toggling stock charts
│   └── (...other files)
└── http-sources/
    ├── amzn.yml  # Example YAML file for defining HTTP sources
    └── deploy.sh          # Script for deploying and creating Fluvio

We have create 3 sub-folders:

server - (express server code)
client - (next.js app)
http-sources - (fluvio configs)

Step 3: Write server code to create APIS

In the created folder server initialize the project with:

bun init

You can use npm also. Using bash for type script.

Install required dependencies:

bun add @fluvio/client cors express yahoo-finance2

Install types also if you are using TypeScript:

bun add -D @types/cors @types/express

Open the index.ts file created while initializing the project and write some code.

import yahooFinance from "yahoo-finance2";

import Express from "express";
import cors from "cors";
import Fluvio, { Offset, type Record, type Topic } from "@fluvio/client";

const PORT = process.env.PORT || 8080;

const PARTITION = 0;
const fluvio = new Fluvio();

const app = Express();
app.use(cors());

// To get current price of share (default to APPL) can be changed if add query `?symbol=MSFT`
app.get("/price", async (req, res) => {
  try {
    let symbol: string;
    if (req.query.symbol == null) {
      symbol = "AAPL";
    } else {
      symbol = String(req.query.symbol);
    }

    const quote = await yahooFinance.quote(symbol);
    const { regularMarketPrice } = quote;

    const payload = {
      symbol: symbol,
      price: regularMarketPrice,
      time: Date.now(),
    };

    return res.json(payload);
  } catch (error) {
    console.log(error);
    return res.status(500).json({
      error: error,
    });
  }
});


// To get stream data for client-side websites requires topic-id.
app.get("/stream/:topic", async (req, res) => {
  try {
    const topic = req.params.topic;

    res.setHeader("Access-Control-Allow-Origin", "*");
    res.setHeader("Cache-Control", "no-cache");
    res.setHeader("Content-Type", "text/event-stream;");
    res.setHeader("Connection", "keep-alive");
    res.setHeader("X-Accel-Buffering", "no");
    res.flushHeaders();

    const client = await fluvio.connect();
    const consumer = await client.partitionConsumer(topic, PARTITION);
    await consumer.stream(Offset.FromEnd(), async (record: Record) => {
      const eventData = record.valueString();
      const responseMsg = `data: ${JSON.stringify(eventData)}\n\n`;
      res.write(responseMsg);
      res.write("\n\n");
    });

    res.on("close", () => {
      res.end();
    });
  } catch (error) {
    console.log(error);
    return res.status(500).json({
      error: error,
    });
  }
});

// To get all the stocks topics
app.get("/list", async (_, res) => {
  try {
    await fluvio.connect();
    let admin = await fluvio.admin();
    let topicsStr = await admin.listTopic();

    let topics = JSON.parse(topicsStr);

    let payload = topics.map((topic: Topic) => {
      return {
        name: topic.name,
      };
    });

    return res.json(payload);
  } catch (error) {
    console.log(error);
    return res.status(500).json({
      error: error,
    });
  }
});

app.listen(PORT, () => {
  console.log(`Server running on http://localhost:${PORT}/`);
});

It is a very basic express API server with mainly 3 endpoints:

/list: To get the list of topics from fluvio. Topics are like a river with flowing data. In our case, we will have topics for stocks like amzn- Amazon msft - Microsoft, etc We will name topics with stock symbols of the company that will help as you see more in the project.
/price: This endpoint is for fluvio here we have the stock symbol default to appl it can be changed with the query ?symbol=[STOCK]. We are fetching the price from yahoo-finance2 package.
/stream/:topic: This endpoint is very important because it uses a server-side event stream to distribute real-time data from fluvio to client apps.

Step 4: Create a next.js app

Comeon We all know how to create a next.js project do this yourself you are a dev! make a project with typescript, tailwindcss, and app dir.

Install required dependencies:

bun add moment recharts

Now create a folder named components and add 2 files"

StockChart.tsx
StockSwitch.tsx

StockChart.tsx

"use client";

import { useEffect, useState } from "react";

import {
  LineChart,
  Line,
  CartesianGrid,
  XAxis,
  YAxis,
  Tooltip,
} from "recharts";
import moment from "moment";
import { useSearchParams } from "next/navigation";

type StockData = {
  symbol: string;
  price: number;
  time: string;
};

const StockChart = () => {
  const searchParams = useSearchParams();

  const symbol = searchParams.get("symbol") ?? "appl";

  const [chartData, setChartData] = useState<StockData[]>([]);

  const TOPIC_NAME = symbol;
  useEffect(() => {
    const sse = new EventSource(`http://localhost:8080/stream/${TOPIC_NAME}`);

    sse.onmessage = (event) => {
      try {
        const preParsedData = JSON.parse(event.data);
        const parsedData = JSON.parse(preParsedData);

        setChartData((prevData) => [
          ...prevData,
          {
            price: parsedData.price,
            symbol: parsedData.symbol,
            time: moment(new Date(parsedData.time)).format("hh:mm:ss A"),
          },
        ]);
      } catch (error) {
        console.log("Error parsing SSE data:", error);
      }
    };
    return () => {
      sse.close();
    };
  }, [TOPIC_NAME]);

  const formatYAxis = (price: number) => {
    return `$${price.toFixed(0)}`;
  };

  return (
    <div>
      <h1 className="font-semibold text-xl">
        Real-time {symbol.toUpperCase()} Stock Prices
      </h1>

      <LineChart
        width={820}
        height={400}
        data={chartData}
        margin={{ top: 20, right: 30, bottom: 10, left: 10 }}
      >
        <CartesianGrid stroke="#f5f5f5" />
        <XAxis dataKey="time" />
        <YAxis tickFormatter={formatYAxis} />
        <Tooltip />
        <Line type="monotone" dataKey="price" stroke="#8884d8" />
      </LineChart>
    </div>
  );
};

export default StockChart;

This component is a client-side component that fetches real-time events from the express API server we created. You can analyse the code It has a very simple Chart with Price and time. One State to set stock data and get a stock symbol from search params.

StockSwitch.tsx


import Link from "next/link";
import React from "react";

type Stock = {
  name: string;
};

const fetchlist = async () => {
  const res = await fetch("http://localhost:8080/list");

  const data: Stock[] = await res.json();
  if (res.ok) {
    return data;
  } else {
    return [];
  }
};

export default async function StockSwitch() {
  const stocks = await fetchlist();

  return (
    <div>
      <ul>
        {stocks.map((stock) => (
          <li>
            <Link
              href={`?symbol=${stock.name}`}
              className="text-blue-500 font-semibold hover:underline"
            >
              {stock.name}
            </Link>
          </li>
        ))}
      </ul>
    </div>
  );
}

A very simple component fetches data and populates the topics from fluvio using our express server API.

Now link all the parts in `page.tsx`

import StockChart from "@/components/StockChart";
import StockSwitch from "@/components/StockSwitch";
import Link from "next/link";

export default function Home() {
  return (
    <div className="flex p-2 flex-col justify-center h-screen items-center">
      <main>
        <h1>Welcome to the Stock Charts</h1>
        <StockChart />
        <div className="mt-4">
          <p className="text-lg font-medium text-gray-700">Other Stocks</p>
          <StockSwitch />
        </div>
      </main>

      <footer>
        <p>
          Powered by{" "}
          <Link className="text-blue-500" href={"https://www.fluvio.io"}>
            Fluvio
          </Link>{" "}
          Realtime Data flow.
        </p>
      </footer>
    </div>
  );
}

Step 5: Real magic of Fluvio!

Create a folder named http-sources as shown in the project structure.
Create [STOCKNAME].yml files for stock prices
Creating one for appl:

apiVersion: 0.1.0

meta:
  version: 0.2.5
  name: stock-appl
  type: http-source
  topic: appl

http:
  endpoint: "http://localhost:8080/price?symbol=APPL"
  method: GET
  interval: 3s

In this file, we are using a source connector http-source and pulling data from our express API server. With GET method with 3s interval.

You can add more stocks like this with just [STOCKNAME] change (example.yml):

apiVersion: 0.1.0

meta:
  version: 0.2.5
  name: stock-{STOCKNAME}
  type: http-source
  topic: {STOCKNAME}

http:
  endpoint: "http://localhost:8080/price?symbol={STOCKNAME}"
  method: GET
  interval: 3s

STEP 6: The now final step of the game

Inside http-sources folder run command:

cdk hub download infinyon/http-source@0.3.8

This will download the file required for fluvio yml.

Create a topic in fluvio (remember topic name should be unique and should be the same as written in .yml file for me it is {STOCKNAME} or apply)

Run command:

fluvio topic create appl

Lastly deploy the .yml file: cdk deploy start –ipkg infinyon-http-source-0.3.8.ipkg -c appl.yml

--ipkg is the file downloaded from previous command -c is the .yml file name.

To make your life more easier I wrote a deploy.sh file that will do this Slep 6 with one command:

deploy.sh:

#!/bin/bash

# Set variables
PACKAGE_NAME="infinyon-http-source-0.3.8"
PACKAGE_VERSION="0.3.8"
PACKAGE_IPKG="${PACKAGE_NAME}.ipkg"
PACKAGE_URL="infinyon/http-source@${PACKAGE_VERSION}"
HTTP_SOURCES_DIR="."

# Function to download the package if it doesn't exist
download_package() {
  if [ ! -f "${HTTP_SOURCES_DIR}/${PACKAGE_IPKG}" ]; then
    echo "Package ${PACKAGE_IPKG} not found. Downloading..."
    cdk hub download ${PACKAGE_URL} -o ${HTTP_SOURCES_DIR}
  else
    echo "Package ${PACKAGE_IPKG} already exists."
  fi
}

# Function to deploy configurations
deploy_configurations() {
  for file in ${HTTP_SOURCES_DIR}/*.yml; do
    if [ -f "$file" ] && [ "$(basename "$file")" != "example-source.yml" ]; then
      echo "Deploying ${file}..."
      echo "Command: cdk deploy start --ipkg ${PACKAGE_IPKG} -c ${file}"
      cdk deploy start --ipkg ${PACKAGE_IPKG} -c ${file}
    else
      echo "Skipping ${file}."
    fi
  done
}

# Function to create Fluvio topics
create_topics() {
  for file in ${HTTP_SOURCES_DIR}/*.yml; do
    if [ -f "$file" ] && [ "$(basename "$file")" != "example-source.yml" ]; then
      # Extract the topic using sed
      topic=$(sed -n 's/^[[:space:]]*topic:[[:space:]]*\(.*\)/\1/p' "$file")
      if [ -n "$topic" ]; then
        # Check if the topic already exists
        if fluvio topic list | grep -q "^${topic}$"; then
          echo "Topic ${topic} already exists. Skipping creation."
        else
          echo "Creating Fluvio topic ${topic}..."
          fluvio topic create ${topic}
        fi
      else
        echo "No topic found in ${file}."
      fi
    else
      echo "Skipping ${file}."
    fi
  done
}

# Main script execution
download_package
create_topics
deploy_configurations

echo "Script execution completed."

Run Command:

./deploy.sh

Now you are good to go.

Finishing Up.

Run client and server

go inside /client run bun dev
go inside /server run bun run index.ts

Now open https://localhost:3000 and see your application.

Things can extend

add more stocks
make a good UI
add authentication
…more.

This was for this article Source Repo: https://github.com/priyanshuverma-dev/stock-charts

Thanks, Priyanshu Verma

Fluvio - An open-source In-motion data framework.