Database per service pattern in Microservices - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a microservice with its own database.

Microservices

class OrderService {
    constructor() {
        this.db = new [1]();
    }
}

Drag options to blanks, or click blank then click option'

AOrderDatabase

BCommonStorage

CSharedDatabase

DGlobalDB

Attempts:

3 left

💡 Hint

Common Mistakes

Using a shared or global database instead of a service-specific one.

The Database per service pattern means each microservice has its own dedicated database. Here, OrderDatabase represents the database specific to the OrderService.

2fill in blank

medium

Complete the code to ensure data isolation between services.

Microservices

function getUserData() {
    return [1].query('SELECT * FROM users');
}

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ASharedDB

BGlobalUserDB

CUserServiceDB

DCommonDB

Attempts:

3 left

💡 Hint

Common Mistakes

Querying a shared or global database causing data coupling.

Each microservice should query its own database to maintain data isolation. Here, UserServiceDB is the database dedicated to the UserService.

3fill in blank

hard

Fix the error in the service communication to avoid direct database sharing.

Microservices

class PaymentService {
    constructor() {
        this.db = new [1]();
    }

    processPayment() {
        // Should not access OrderService database directly
        this.db.query('UPDATE orders SET status = "paid" WHERE id = 123');
    }
}

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APaymentDatabase

BOrderDatabase

CSharedDatabase

DGlobalDB

Attempts:

3 left

💡 Hint

Common Mistakes

Using another service's database directly causing tight coupling.

PaymentService must use its own database (PaymentDatabase) and communicate with OrderService via APIs, not by accessing its database directly.

4fill in blank

hard

Fill both blanks to implement service communication without sharing databases.

Microservices

class InventoryService {
    constructor() {
        this.db = new [1]();
    }

    updateStock(orderId) {
        // Notify OrderService via [2]
        this.notifyOrderService(orderId);
    }
}

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AInventoryDatabase

BDirectDBAccess

CMessageQueue

DSharedDatabase

Attempts:

3 left

💡 Hint

Common Mistakes

Using shared databases or direct DB access for communication.

InventoryService uses its own InventoryDatabase and communicates with OrderService through a MessageQueue, avoiding direct database sharing.

5fill in blank

hard

Fill all three blanks to implement a microservice with isolated database and API communication.

Microservices

class ShippingService {
    constructor() {
        this.db = new [1]();
    }

    notifyOrderService(shippingId) {
        fetch(`http://orderservice/api/orders/[2]`, {
            method: '[3]',
            body: JSON.stringify({ shippingId })
        });
    }
}

Drag options to blanks, or click blank then click option'

AShippingDatabase

BupdateShippingStatus

CPOST

DSharedDB

Attempts:

3 left

💡 Hint

Common Mistakes

Using shared databases or incorrect HTTP methods.

ShippingService uses its own ShippingDatabase. It communicates with OrderService by calling the updateShippingStatus API endpoint using the POST method, following the database per service pattern.