Microservices 1 - Introdcution to Microservices

Introduction to Microservices

Microservices is an architectural style that structures an application as a collection of small, independent, and loosely coupled services. Each of these services is designed to do one thing well. This is in contrast to a monolithic architecture, where an application is built as a single, unified block.

The Monolithic Approach

• Imagine a traditional e-commerce application built using a monolithic architecture.

• It might have the following features:

  • User Management: Registering users, logging in, managing profiles.
  • Product Catalog: Listing products, searching for them.
  • Order Management: Handling the process of placing orders.
  • Payment Processing: Managing payment methods and processing payments.
  • Inventory Management: Keeping track of stock levels.
  • Shipping: Managing shipping options and tracking deliveries.

• In a monolithic architecture, all these features would be part of one big application, which means:

  • All features are interdependent.
  • The whole application is developed, deployed, and scaled as a single unit.
  • If one part of the system needs an update (like adding a new payment method), the entire application must be redeployed.

• This can lead to challenges:

  • Complexity: As the application grows, it becomes harder to manage and understand.
  • Scaling: You can’t scale just one part of the application; you have to scale the whole thing, which might be inefficient.
  • Deployment: A small change in one area (e.g., user management) requires redeploying the entire application, increasing the risk of introducing bugs elsewhere.
  • Flexibility: Different parts of the application may have different requirements or be written in different programming languages, which is difficult to accommodate in a monolithic structure.

The Microservices Approach

• Now, let’s imagine that same e-commerce application built using a microservices architecture.
• Instead of one large application, the system is divided into multiple small services, each handling a specific function:

1. User Service: Manages user accounts, authentication, and profiles.
2. Product Service: Handles product listings, search, and details.
3. Order Service: Manages the process of placing and tracking orders.
4. Payment Service: Handles all aspects of payment processing.
5. Inventory Service: Keeps track of stock levels and availability.
6. Shipping Service: Manages shipping options, tracking, and delivery.

• These services communicate with each other over a network, typically using APIs (Application Programming Interfaces).

Benefits of Microservices:

• Independence: Each service can be developed, deployed, and scaled independently. If you need to update the Payment Service, you can do so without touching the other services.
• Scalability: If you have a spike in traffic on the Product Service, you can scale just that service without affecting others.
• Flexibility: Different services can use different programming languages or technologies that best suit their specific needs.
• Resilience: If one service fails (e.g., the Shipping Service), it doesn’t necessarily bring down the entire system. Other services can continue functioning.

Example in Action:

• Imagine you’re visiting an e-commerce website to buy a new phone.

• Here’s how the microservices would work together:

  1. User Service: You log in to the website. The User Service handles your authentication.
  2. Product Service: You search for phones, and the Product Service returns a list of available phones.
  3. Order Service: You add a phone to your cart and proceed to checkout. The Order Service manages your cart and finalizes your order.
  4. Payment Service: You enter your payment details, and the Payment Service processes your payment securely.
  5. Inventory Service: Before confirming the order, the Inventory Service checks if the phone is in stock.
  6. Shipping Service: After payment, the Shipping Service arranges the delivery of your phone.

If the Shipping Service goes down while you’re browsing, you might not be able to see shipping options, but you can still browse products, place items in your cart, or even pay for your order. The rest of the application remains functional.

Challenges of Microservices

While microservices offer many advantages, they also come with their own set of challenges:

• Complexity in Management: Managing multiple services can be complex, especially as the number of services grows.
• Inter-service Communication: Ensuring reliable communication between services can be difficult and may introduce latency.
• Data Consistency: Since each service manages its own data, maintaining data consistency across services can be tricky.
• Deployment and Monitoring: Each service needs to be deployed and monitored separately, which requires a strong DevOps culture and sophisticated tools.

What is a microservices architecture?

• In a microservices architecture, a large application is split up into a set of smaller services.
• Each service runs in its own process and communicates with other processes by using protocols like HTTP/HTTPS, WebSocket, or Advanced Message Queuing Protocol (AMQP).
• Each microservice implements a specific, end-to-end domain or business capability within a certain context boundary.
• Each microservice must be developed autonomously and must be independently deployable.
• Finally, each microservice should own its related domain data model and domain logic.
• Microservices can be based on different data storage technologies (SQL, NoSQL) and different programming languages.

Characteristics of Microservices

• Here are some key characteristics of microservices:
  • They’re small, independent, and loosely coupled. Each microservice has a separate code base that a small development team can manage.
  • They’re deployed independently. A team can update an existing microservice without rebuilding and redeploying the entire application.
  • They persist their data or the external state in their respective databases. Unlike in a monolithic architecture, microservices don’t share databases.
  • They communicate with each other by using well-defined APIs. Internal implementation details of each service are hidden from other services.
  • They support polyglot programming. For example, the microservices that make up a web application don’t need to share the same technology stack, libraries, or frameworks.

What role do containers play?

• Containerization Overview:

  • Involves packaging an application, its dependencies, and configuration into a container image.
  • The container image can be tested as a unit and deployed on the host OS as an instance.

• Analogy to Shipping Containers:

  • Just as shipping containers transport various goods, software containers provide a standard unit for deploying software with different code and dependencies.
  • Enables easy deployment across environments with minimal modification.

• Fit with Microservices Architecture:

  • Containerization is well-suited for implementing microservices architecture.
  • The benefits of containers closely align with the advantages of a microservices approach.

Orchestrators and Microservices

Orchestrators and Microservices

• Orchestrators Overview:

  • Tools that automate the deployment, scaling, and management of containerized applications.
  • Examples include Kubernetes, Docker Swarm, and Apache Mesos.
• A cluster is one type of orchestrator.
• The following diagram illustrates using a cluster to orchestrate the deployment of an application that’s composed of multiple microservices.