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Getting Started with Microservices Architecture

In this article, I will discuss Getting Started with Microservices Architecture. So, I will discuss what was there before microservices, what problem we face in that architecture, and how we overcome the problem using Microservices. Then, I will discuss the Architecture of Microservices, the Pros and Cons of Microservices, and finally, we will conclude with the real-time applications of Microservices. Before Microservices, we have Monolithic Architecture, so let us proceed and understand Monolithic Architecture.

What is Monolithic Architecture?

Monolithic architecture is a traditional software design approach where an entire application or system is built as a single, interconnected unit. In a monolithic architecture, all components, functionalities, and modules are tightly integrated into a single codebase and deployed together as a single unit.

A monolithic architecture is a singular, large computing network with one code base that couples all of the business concerns together.  Changing this sort of application requires updating the entire stack by accessing the code base and building and deploying an updated version of the service-side interface. This makes updates restrictive and time-consuming. 

Monoliths can be convenient early on in a project’s life for ease of code management, cognitive overhead, and deployment. This allows everything in the monolith to be released at once.

Key Characteristics of a Monolithic Architecture:

• Single Codebase: All application components are developed within a single code repository.
• Tight Coupling: Components are tightly interconnected since they share the same codebase, data storage, and often the same memory space.
• Single Deployment Unit: The entire application is deployed as a single unit, meaning that updates or changes to any part of the application require the whole application to be redeployed.
• Single Technology Stack: The application typically uses a single technology stack, programming language, and framework throughout.
• Scalability Challenges: Scaling individual components independently can be challenging because the entire application needs to be replicated for scalability.
• Development and Testing: As the application grows, development and testing can become complex and time-consuming due to the interconnected nature of the components.
• Limited Flexibility: Monolithic architectures can become unwieldy and inflexible as the application becomes larger and more complex.
• Risk of Downtime: Updates, bug fixes, and maintenance tasks can lead to downtime for the entire application.

Monolithic architectures have been widely used for many years and are suitable for simpler applications and projects where the codebase remains manageable. However, they can become problematic as applications grow in size and complexity. Changes or updates to a single component might impact the entire application, and scaling specific parts of the application independently can be difficult.

Monolith means composed all in one piece. The Monolithic application describes a single-tiered software application in which different components are combined into a single program from a single platform. Components can be:

• Authorization: Responsible for authorizing a user
• Presentation: Responsible for handling HTTP requests and responding with either HTML or JSON/XML (for web services APIs).
• Business Logic: The application’s business logic.
• Database Layer: Data access objects responsible for accessing the database.
• Application Integration: Integration with other services (e.g., via messaging or REST API). Or integration with any other Data sources.
• Notification Module: Responsible for sending email notifications whenever needed.

Monolith Architecture Components:

• User Interface (UI): The UI component includes the user-facing part of the application, including web pages, user interfaces, and frontend code. It interacts with the application’s backend to request and display data.
• Application Logic: The application logic includes the core business functionality of the application. This logic handles tasks like processing user requests, calculating, and implementing business rules.
• Database: The database stores the application’s data. In a monolith architecture, a single, shared database usually serves all application components.
• Communication: Components within the monolith communicate directly with each other, typically using function calls, method invocations, or shared libraries. This tight coupling can make it easier to share data and functionality but can also lead to challenges as the application grows.
• Monolithic Codebase: The entire application codebase is contained within a single project. This codebase includes all the components, logic, and functionality required to run the application.
• Deployment Unit: The monolithic application is deployed as a single unit. This means that any updates or changes to the application require deploying the entire codebase, which can lead to downtime during deployments.
• Technology Stack: The application uses a consistent technology stack throughout, including the programming language, libraries, and frameworks used for both the front and back end.
• Scaling: Scaling a monolith can be challenging. Since the entire application is a single unit, horizontal scaling involves replicating the entire application stack, which can be resource-intensive.
• Maintenance: As the application grows, the monolithic codebase can become complex and harder to maintain. Changes to one part of the application can inadvertently affect other parts.
• Testing: Testing the monolith involves testing the entire application as a single unit. End-to-end testing can be complex due to the integrated nature of the components.

In a monolith architecture, the tightly integrated nature of the components can simplify development and initial setup. However, scalability, maintenance, and complexity challenges can arise as the application grows. While monoliths have their advantages, they might not be the best fit for applications with complex requirements, the need for independent scaling, or teams with varying development paces.

Pros of Monolithic Architecture

• Simplicity: Monolithic architectures are relatively simpler to develop and manage, especially for small to moderately-sized applications. There’s a single codebase to work with, making development and debugging straightforward.
• Ease of Deployment: Since the entire application is a single unit, deployment is often easier and less complex than distributed systems.
• Consolidated Data: Data management and storage are centralized, which can simplify database operations and ensure data consistency.
• Performance: In some cases, monolithic architectures can offer better performance because there is no overhead associated with inter-service communication, which is common in microservices architectures.
• Easier Testing: Testing the entire application as a single unit can be simpler, and end-to-end testing is easier to manage.
• Technology Homogeneity: Since the entire application uses a single technology stack, developers don’t need to be proficient in multiple technologies.
• It is simple to scale horizontally by running multiple copies behind a load balancer.

Cons of Monolithic Architecture

• Scalability: Monolithic applications can be challenging to scale horizontally. As the application grows, you need to scale the entire monolith, even if only specific components need more resources.
• Flexibility: Adding new features or making changes can be more challenging as the application becomes larger. A change in one part of the application might impact other parts.
• Maintenance Complexity: As the application size increases, maintaining and upgrading the application can become complex and error-prone.
• Downtime Risk: Deploying updates or fixes to one part of the application might require the entire application to be taken offline.
• Team Collaboration: Collaboration among development teams can become more difficult as the application grows, leading to potential bottlenecks and slower development cycles.
• Technology Limitations: If a particular technology or framework becomes outdated or inefficient, the entire application might need to be refactored to adopt a newer technology.
• Resource Allocation: Resources (e.g., memory, CPU) are allocated to the entire application, potentially leading to inefficient resource usage.
• Limited Language and Framework Choices: All components must use the same programming language and framework, which might not be the best choice for all application parts.

The monolithic architecture is suitable for smaller applications with relatively straightforward requirements. It offers simplicity in development and deployment. However, as applications grow in complexity and size, monolithic architectures can become limiting in terms of scalability, maintainability, and the ability to adopt new technologies. Many organizations are transitioning to microservices or other architectural patterns to address these limitations while maintaining flexibility and scalability.

What is Microservices Architecture?

Microservices architecture is a software design approach where an application is divided into a collection of small, loosely coupled, and independently deployable services. Each service focuses on a specific business capability and communicates with other services over well-defined APIs. Microservices aim to promote flexibility, scalability, and maintainability by breaking down a complex application into smaller, more manageable parts.

Consider the same example of the e-commerce application, which consists of several components/modules. Define each component/module as a separate loosely coupled service depending on the requirement, which may collaborate with each other based on the scenario. We can have the following services for a complete application:

• Authorization Service: Responsible for authorizing customers.
• Order Service: Takes an order and processes it.
• Catalog Service: Manage products and check product inventory.
• Cart Service: Manage user cart; this service can utilize Catalog Service as a data source.
• Payment Service: Manage and Authorize payments.
• Shipping Service: Ships ordered products.

Pros of Microservices

• Scalability: Services can be scaled independently based on demand, allowing efficient resource allocation and cost savings.
• Flexibility and Agility: Development teams can work on and deploy services independently, enabling faster development cycles and the ability to respond quickly to changing requirements.
• Technology Diversity: Different services can use the most appropriate technologies and programming languages for their specific tasks, promoting innovation and optimization.
• Isolation and Resilience: Faults in one service are less likely to affect the entire application. Isolation can improve system resilience and availability.
• Modularity: Each service focuses on a specific business capability, making managing and understanding the application’s complexity easier.
• Autonomous Teams: Development teams can take ownership of specific services, leading to greater autonomy, faster decision-making, and increased innovation.
• Continuous Delivery: Independent deployment allows for continuous integration and continuous delivery practices, facilitating faster and more reliable software releases.
• Easier Maintenance: Updates and bug fixes can be applied to specific services without impacting the entire application.

Cons of Microservices

• Service Communication Complexity: Inter-service communication can introduce challenges such as latency, message consistency, and network failures. Proper communication patterns and tools are essential.
• Operational Overhead: Managing and monitoring multiple services can be more complex and resource-intensive than a monolithic application.
• Data Management: Maintaining data consistency and integrity across multiple services can be complex, especially when services have their databases.
• Service Discovery: Mechanisms are needed to help services find and communicate with each other, especially in dynamic and containerized environments.
• Testing Challenges: End-to-end testing becomes more complex due to the interactions between multiple services. Ensuring comprehensive test coverage requires careful planning.
• Distributed Complexity: Debugging and tracing issues across distributed services can be challenging, requiring specialized tools and practices.
• Initial Development Overhead: Developing the infrastructure, tooling, and initial set of services can introduce upfront complexity and costs.
• Skills and Expertise: Development teams need a strong understanding of distributed systems concepts and practices, which may require additional training and expertise.
• Increased Latency: Inter-service communication can introduce latency compared to in-process function calls in a monolithic application.
• Deployment Complexity: Coordinating the deployment of multiple services can be more challenging than deploying a single monolithic application.

The microservices architecture benefits applications with complex requirements, scalability needs, and a desire for independent development and deployment. However, it introduces communication, monitoring, testing, and data management challenges. Organizations should carefully assess their specific needs, team expertise, and potential benefits and challenges before adopting a microservices architecture.

Microservices Communication

Let me tell you how we’ll communicate between the Microservices and simple monolithic applications. In the case of Monolithic architecture, we have tables and relations, and services can talk to each other with the help of relations because these services share the same database, not in the case of Microservices.

Each Service contains its own data store. So, how is it possible to communicate with other microservices when there are multiple ways where one microservices can talk to other microservices?

Imagine an e-commerce platform that consists of several microservices like customers, products, baskets, inventory, payments, orders, and email to handle different aspects of the system. These microservices need to communicate with each other to provide a seamless shopping experience for users.

• Product Catalog Service: This microservice manages product information, including details like name, price, description, and availability. When a user wants to view a product, the Product Catalog Service is responsible for providing the necessary information.
• User Authentication Service: This microservice handles user registration, login, and authentication. It issues authentication tokens upon successful login, which can be used to identify users.
• Shopping Cart Service: Users can add products to their shopping carts. This microservice is responsible for managing the contents of the shopping cart, including adding, updating, and removing items.
• Order Management Service: Once a user decides to place an order, the Order Management Service creates and processes orders. It handles order confirmation, payment processing, and order fulfillment.

Now, let’s look at how these microservices might communicate:

Synchronous Communication:

When a user wants to view a product, the front-end application might send a request to the Product Catalog Service. The service responds with the product details, and the front end displays them.

When a user adds items to their shopping cart, the Shopping Cart Service is notified. The front end waits for a response to ensure the item was successfully added.

Asynchronous Communication:

After a user places an order, the Order Management Service might need to notify the Shipping Service to prepare the items for shipment. This communication could be asynchronous to avoid delaying the order confirmation for the user.

The User Authentication Service might emit events when a user logs in successfully. Other services interested in this event (e.g., personalized recommendations) can consume it and take appropriate actions.

API Gateway:

An API Gateway can be used to provide a unified interface to clients (such as web and mobile apps). It routes requests to the appropriate microservices and handles authentication and authorization.

Message Brokers:

To enable asynchronous communication, message brokers like Apache Kafka or RabbitMQ can be utilized. Services can publish messages related to events (e.g., order placed), and other services can subscribe to these messages to take actions accordingly.

A message broker is a software that enables the applications, systems, and services to communicate with each other and exchange information.

Okay, what happens is when the customer places the order, the data will go to the message broker or, in short, will send the data to the message broker.

On the other hand, the email service will interact with the message broker and get the order details from this message broker. If the payment is successful, this e-mail service will email the customer that the order has been placed successfully. So, this type of communication, which happens with a message broker, is an external microservice communication or asynchronous communication.

Service Discovery:

Since microservices might be dynamically scaled or deployed on different servers, service discovery mechanisms (like Consul or Kubernetes’ service discovery) can help services find each other’s endpoints.

Remember, the choice of communication style (synchronous vs. asynchronous) and tools (API Gateway, message brokers, etc.) depends on factors like system complexity, latency requirements, and scalability needs. In a real-world scenario, microservices architecture can greatly enhance the flexibility, maintainability, and scalability of an e-commerce platform. Still, it also introduces challenges regarding proper communication, data consistency, and fault tolerance.

Difference Between Monolith Architecture and Microservice

Monolith architecture and microservices architecture are distinct approaches to designing and building software applications. They differ in terms of structure, scalability, modularity, and how components are organized and interact. Here’s a comparison of the key differences between monolith architecture and microservices architecture:

Monolith Architecture

• Structure: The entire application is built as a single, tightly integrated unit in a monolith architecture. All components, modules, and functionalities are part of the same codebase.
• Modularity: Monoliths typically lack clear boundaries between different modules and functionalities. This can lead to challenges in maintenance and scalability as the application grows.
• Deployment: The entire monolithic application is deployed as a single unit. Updates and releases require deploying the entire application, which can lead to downtime and impact users.
• Scalability: Monoliths can be challenging to scale horizontally because scaling requires duplicating the entire application stack, even if only specific parts need additional resources.
• Technology Stack: Monoliths tend to have a consistent technology stack throughout the application since all components are tightly integrated.
• Team Structure: Teams working on a monolith might need to collaborate closely since changes in one part of the application can affect other parts.
• Complexity: As monoliths grow, they can become complex and harder to understand, leading to maintenance and troubleshooting challenges.
• Innovation: Implementing new technologies or experimenting with new features can be more challenging in a monolith due to its tightly integrated nature.

Microservices Architecture:

• Structure: In a microservices architecture, an application comprises small, independently deployable services, each responsible for a specific business functionality.
• Modularity: Microservices emphasize modularity and clear boundaries between services. Each service is a separate unit with its own codebase and functionality.
• Deployment: Microservices can be deployed independently. This enables continuous deployment and releases without impacting the entire application.
• Scalability: Microservices allow for fine-grained scalability. Only the specific services experiencing high demand need to be scaled, avoiding over-provisioning resources.
• Technology Stack: Different microservices can use different technologies and languages, allowing each service to use the best tool for the job.
• Team Structure: Microservices promote team autonomy, allowing teams to work independently on different services.
• Complexity: Microservices can help manage complexity by breaking down the application into smaller, manageable components. However, managing the interactions between services can introduce its own complexities.
• Innovation: Microservices make experimenting with new technologies or features easier since changes can be made to individual services without affecting the entire application.

So, the main difference between monolith architecture and microservices architecture lies in how the application is structured, deployed, and maintained. Monoliths are single, integrated units, while microservices divide the application into smaller, independently deployable services. The choice between these architectures depends on the specific needs of the application, the development team’s capabilities, and the desired balance between modularity and complexity.

When to Use Microservices?

In this, we will talk about when we should use Microservices and when we should not use Microservices. But before this, let’s compare the Microservices with monolithic applications. Now, let’s talk about the deployment of the monolithic application. You have to publish or redeploy the whole application.

But in the case of Microservices, you can deploy only the highlighted part, and then you can also deploy the other microservices.

Consider the following factors.

• Scalability: It’s much easier to scale the microservices.
• Platform Dependent: In monolithic, we have to create all the services (vehicles, customers, reservations) in the same programming language and with the same database. In microservices, we can create vehicle services in .NET Core, customers in Python, and reservations services in NodeJS. You can also use different databases like MSSQL, MYSQL, MongoDB, etc.
• Development Speed: In enterprise-level microservices, each developer is associated with some particular service, making fewer errors possible. One developer has to write the whole application code in a monolithic system.

When Should We Use Microservices?

Microservices architecture is applied in various real-time use cases across different industries to address specific challenges and leverage its benefits. Here are some real-time use cases of microservices:

E-Commerce Platforms:

• Order Management: Each step of the order process, from browsing to payment and fulfillment, can be managed by separate microservices to ensure flexibility, scalability, and faster response times.
• Product Catalog: Services for product information, availability, and pricing can be decoupled to manage high-traffic loads during sales and events.

Ride-Sharing Apps:

• Location Tracking: Services for real-time location tracking and ride allocation can be built as separate microservices to ensure accurate tracking and efficient ride assignment.
• Payment Processing: Independent services can handle payment transactions, ensuring quick and reliable payment processing.

Online Gaming:

• Matchmaking: Microservices can handle player matchmaking, balancing teams, and ensuring a seamless gaming experience.
• User Authentication: Separate services can manage user profiles, authentication, and authorization for secure and efficient access to game resources.

Financial Services:

• Payment Processing: Microservices can process transactions, verify fraud, and update account balances in real-time.
• Trading Platforms: Independent services can handle order execution, trade settlement, and real-time market data updates.

IoT (Internet of Things):

• Sensor Data Processing: Microservices can process incoming sensor data from devices, trigger alerts, and manage device communication.
• Analytics: Services can process and analyze real-time data streams from IoT devices to provide insights and actionable information.

Media Streaming:

• Video Streaming: Microservices can manage video encoding, storage, streaming, and delivery to ensure smooth and high-quality streaming experiences.
• User Recommendations: Separate services can analyze user preferences and viewing history to deliver personalized content recommendations.

Healthcare Applications:

• Electronic Health Records: Microservices can handle patient records, appointments, and medical history while ensuring data security and compliance.
• Telemedicine: Independent services can support real-time video consultations, appointment scheduling, and remote diagnostics.

Logistics and Supply Chain:

• Route Optimization: Microservices can calculate the optimal delivery routes, considering real-time traffic data and delivery constraints.
• Inventory Management: Services can monitor inventory levels in real time, trigger restocking, and manage order fulfillment.

Social Networking Platforms:

• User Activity Feeds: Microservices can manage real-time updates of user activity feeds, notifications, and interactions.
• User Authentication: Separate services can handle user sign-up, login, and account management.

Travel and Hospitality:

• Booking and Reservation: Microservices can handle real-time booking, availability checks, and reservation management for hotels, flights, and other services.
• Reviews and Ratings: Independent services can manage user reviews, ratings, and feedback for better customer engagement.

These are just a few examples of how microservices architecture can be applied in real-time scenarios to provide scalability, flexibility, and responsiveness to rapidly changing demands. The suitability of microservices for a specific use case depends on factors like the application’s complexity, scalability requirements, and the organization’s technical expertise.

In the net article, I am going to explain the Project Setup for Microservices in ASP.NET Core Web API. In this article, I try to give an overview of Microservices Architecture. I hope you enjoy this Getting Started with Microservices Architecture.