Chapter 1: Introduction to Microservices with Deno

My journey into creating microservices using Deno has been one filled with exploration and creativity. By utilizing Deno's advanced runtime environment, which offers excellent support for TypeScript, I set out to develop two interlinked microservices: a User Service and an Order Service. Below, I will outline my approach step-by-step.

Chapter 2: Developing the User Service

Step 1: Initializing the User Service

Within the user-service directory, I set up a deps.ts file to import the necessary modules from Deno's standard library and any third-party libraries.

// user-service/deps.ts

Step 2: Building the Application

In app.ts, I created a straightforward web server capable of executing CRUD operations for managing users.

// user-service/app.ts

import { Application, Router } from "./deps.ts";

const router = new Router();

router

.get("/users", ({ response }) => {

response.body = "Retrieving all users...";

})

.post("/users", ({ response }) => {

response.body = "Adding a new user...";

});

const app = new Application();

app.use(router.routes());

app.use(router.allowedMethods());

await app.listen({ port: 8000 });

console.log("User Service running on port 8000");

Chapter 3: Constructing the Order Service

Step 1: Initializing the Order Service

Following a similar approach to the User Service, I created a new Deno project within the order-service directory. This involved setting up an app.ts for application logic and a deps.ts file for dependency management, focusing on modules necessary for HTTP servers and requests.

// order-service/deps.ts

Step 2: Designing API Endpoints

In the app.ts file, I defined a new set of API endpoints specifically for order management, which included routes for creating, viewing, updating, and deleting orders. Each endpoint was crafted with async functions to effectively handle database interactions and manage request/response flows.

// order-service/app.ts

import { Application, Router } from "./deps.ts";

const router = new Router();

router

.get("/orders", async ({ response }) => {

response.body = "Retrieving all orders...";

})

.post("/orders", async ({ request, response }) => {

// Logic for creating a new order

response.body = "Order has been created";

});

// Additional routes for updating and deleting orders

const app = new Application();

app.use(router.routes());

app.use(router.allowedMethods());

await app.listen({ port: 8001 });

console.log("Order Service running on port 8001");

Chapter 4: Enabling Inter-Service Communication

To facilitate communication between the services, I employed the fetch API available in Deno for making HTTP requests. The following example demonstrates how I modified the order service to check if a user exists before creating an order.

// In the order creation route within order-service/app.ts

async function verifyUser(userId: string): Promise<boolean> {

try {

const response = await fetch(http://localhost:8000/users/${userId});

return response.ok; // Returns true if the user exists

} catch (error) {

console.error("Error verifying user:", error);

return false;

}

}

router.post("/orders", async ({ request, response }) => {

const { userId, ...orderDetails } = await request.body().value;

if (await verifyUser(userId)) {

response.body = { message: "Order created", orderDetails };

} else {

response.status = 400;

response.body = { error: "Invalid user ID" };

}

});

Chapter 5: Running the Services

To observe the services in action, I ran each service in separate terminal windows. For both the user service and order service, I navigated to their respective directories and executed the command:

deno run --allow-net app.ts

Through this project, I've showcased the ease and efficiency of using Deno for building microservices, leveraging its secure defaults and native TypeScript support. For those eager to explore Deno further, I suggest reviewing my articles, "Exploring Deno: The Modern JavaScript and TypeScript Runtime" and "Getting Started with Deno: Setting Up and Building Your First Project."

This guide, based on my personal experience, serves as a foundation for adopting Deno in a microservices architecture. Real-world applications may necessitate a more complex setup, including thorough error handling, robust data validation, and strict security measures such as authentication and authorization.

To continue receiving insights like this, follow me on Medium or subscribe to get my latest stories via email. You might also find value in my curated lists or check out these related articles:

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