Blogs

calendar img
Rahul's Picture
Rahul SaharanSoftware Developerauthor linkedin

First Microservices using Scala

img

Introduction

Embarking on the Scala microservices journey is a thrilling endeavor that opens the door to a world of scalable, efficient, and maintainable software architecture. As a programming language, Scala stands as the perfect companion for this exploration, seamlessly blending the best of both object-oriented and functional paradigms. Let's dive into the introductory landscape, setting the stage for a beginner's guide to crafting your inaugural microservice using Scala.

1. Scala Unveiled: The Language of Elegance

  • Versatility in Paradigms: Scala is renowned for its unique fusion of object-oriented and functional programming concepts. This versatility allows developers to embrace both imperative and declarative styles, providing a comprehensive toolkit for building software solutions.

  • Interoperability with Java: Leveraging the Java Virtual Machine (JVM), Scala boasts seamless interoperability with Java. This means existing Java libraries and frameworks can be effortlessly integrated, making it an attractive choice for projects that require a bridge between these two languages.

  • Conciseness and Readability: Scala's expressive syntax allows developers to write concise and readable code. Features like type inference and pattern matching contribute to reducing boilerplate code, enhancing productivity without sacrificing clarity.

2. Setting the Stage: Preparing for the Journey Ahead

  • Installing the Java Development Kit (JDK): The first step involves ensuring your system is equipped with the necessary tools. Install the JDK, which is the prerequisite for running Scala applications.

  • Configuring Scala Build Tool (sbt): Scala's build tool, sbt, plays a crucial role in managing dependencies and building projects. We'll guide you through the process of configuring sbt to kickstart your Scala microservices project.

3. Crafting the Microservice: The Heart of the Expedition

  • Introduction to Akka HTTP: To build microservices in Scala, we turn to Akka HTTP, a powerful and flexible toolkit for creating web services. We'll explore how Akka HTTP simplifies the process of handling HTTP requests and responses, making microservices development intuitive.

  • Defining Routes: Routes serve as the navigational map for incoming requests. We'll delve into defining routes that guide requests to the appropriate handlers, ensuring a well-organized and scalable microservices architecture.

5. Running the Show: From Local Execution to Deployment

  • Executing Locally: Before deploying your microservice, it's crucial to run it locally. Learn the commands to execute your Scala application, allowing you to witness your creation in action within the development environment.

  • Deployment Considerations: As your microservice evolves, considerations for deploying it in various environments become pivotal. Gain insights into the considerations and potential challenges of deploying your Scala microservice to different platforms.

Why Scala For Microservices ?

Virtual Machine

Choosing a programming language for microservices development involves considering various factors such as expressiveness, scalability, maintainability, and ecosystem support. While the choice ultimately depends on specific project requirements and team expertise, Scala stands out for several reasons, making it an excellent choice for microservices development:

  1. Interoperability with Java:

    • JVM Compatibility: Scala runs on the Java Virtual Machine (JVM), ensuring seamless interoperability with Java. This feature is crucial when integrating with existing Java code, libraries, and frameworks, providing a smooth transition for teams with a Java background.

  2. Strong Type System:

    • Static Typing: Scala's static typing enhances code safety by catching errors at compile-time. This characteristic is advantageous in microservices architectures, where early detection of issues can prevent runtime failures, improving system reliability.

  3. Functional Programming Support:

    • Immutable Data Structures: Scala encourages functional programming practices, including the use of immutable data structures. This feature simplifies state management in microservices, promoting better resilience and ease of reasoning about code.

  4. Scalability and Performance:

    • Concurrency and Parallelism: Scala's support for concurrent and parallel programming, especially with Akka, makes it well-suited for building scalable microservices. The actor model enables efficient resource utilization and scalability.

While Scala excels in various aspects, it's essential to consider project-specific requirements, team expertise, and ecosystem fit when choosing a language for microservices development. Scala's unique combination of features, expressiveness, and ecosystem support makes it a compelling choice for building scalable and maintainable microservices architectures.


Setting the Stage on Linux

Welcome to the Linux edition of "Setting the Stage," where we'll meticulously guide you through the process of setting up your Linux environment for Scala microservices development. Follow these detailed steps to ensure a smooth initiation into the world of Scala.

1. Installing the Java Development Kit (JDK):

a. Open a Terminal:

  • On most Linux distributions, press Ctrl + Alt + T to open a terminal.

b. Update Package List:

  • Run the following commands to update the package list and install essential tools:

1sudo apt update 
2sudo apt install -y software-properties-common

c. Install OpenJDK:

  • Install OpenJDK, the open-source implementation of the Java Platform:

1sudo apt install -y openjdk-11-jdk

d. Verify Installation:

  • Ensure that Java is installed by checking the version:

1java -version
  • You should see information about the installed Java version.

2. Configuring the Scala Build Tool (sbt):

a. Download and Install sbt:

1echo "deb https://repo.scala-sbt.org/scalasbt/debian all main" | sudo tee /etc/apt/sources.list.d/sbt.listecho "deb https://repo.scala-sbt.org/scalasbt/debian /" | sudo tee /etc/apt/sources.list.d/sbt_old.listcurl -sL "https://keyserver.ubuntu.com/pks/lookup?op=get&search=0x2EE0EA64E40A89B84B2DF73499E82A75642AC823" | sudo apt-key add 
2sudo apt-get update
3sudo apt-get install sbt

b. Create Your First sbt Project:

  • Navigate to the directory where you want to create your project and run:

1sbt new scala/scala-seed.g8
  • Follow the prompts to initialize your project.

c. Dependency Management:

  • In your build.sbt file, declare dependencies. For example:

1libraryDependencies += "org.scalatestplus.play" %% "scalatestplus-play" % "5.0.0" % Test

3. Version Control Setup (Optional):

a. Install Git:

  • If Git is not already installed, use the package manager to install it:

1sudo apt install -y git

b. Initialize a Git Repository:

  • Navigate to your project directory and run:

1git init

c. Connect to a Remote Repository (Optional):

  • If you have a remote repository (e.g., on GitHub), follow these optional steps:

1# Add a remote repository 
2git remote add origin <repository_url>
3# Push your initial code to the remote repository
4git push -u origin master

Congratulations! Your Linux environment is now set up for Scala microservices development. You've installed the JDK, configured sbt, and optionally set up version control. In the upcoming chapters, we'll delve into Scala's features and guide you through crafting your first microservice. Get ready for an engaging and hands-on journey into Scala microservices development!

Writing Your First Microservice In Scala

Akka Logo

Now that your development environment is set up, let's jump into creating your first Scala microservice using Akka HTTP.

1. Introduction to Akka HTTP for Web Services:

a. Understanding Akka HTTP:

Akka HTTP is a powerful tool for making web services in Scala. It makes handling HTTP requests and responses easy and efficient.

b. The Power of Routes:

Think of routes as a map for incoming requests. They help direct requests to the right handlers, ensuring your microservices architecture is organized and scalable.

2. Code Walkthrough: Building the Scala Tapestry:

a. Decoding Routing Logic:

Let's explore the code and understand how routing logic works. Routes are like signposts, guiding incoming requests to the right parts of your code.

b. Handling Concurrent Requests with Akka's Actor Model:

We'll delve into Akka's actor model, a way to manage multiple requests at once. Think of actors as efficient workers handling different tasks simultaneously, making your microservice responsive.

3. Putting It All Together: Your First Microservice

a. Project Structure:

Create a new project folder and organize it like this:

1my-scala-microservice 
2|-- src
3| |-- main
4| |-- scala
5| |-- com
6| |-- mycompany
7| |-- Main.scala

b. Dependencies:

In your project settings, include the necessary tools for Akka HTTP:

1name := "my-scala-microservice"
2
3version := "1.0"
4
5scalaVersion := "2.13.6"
6
7libraryDependencies ++= Seq(
8 "com.typesafe.akka" %% "akka-http" % "10.2.6",
9 "com.typesafe.akka" %% "akka-http-spray-json" % "10.2.6"
10)

Run sbt compile to get these tools.

c. Main.scala (Main Application):

Create a file called Main.scala with the following code:

1package com.mycompany  
2import akka.actor.ActorSystem
3import akka.http.scaladsl.Http
4import akka.http.scaladsl.server.Directives._
5import akka.stream.ActorMaterializer
6import scala.concurrent.ExecutionContextExecutor
7
8
9object Main extends App {
10 implicit val system: ActorSystem = ActorSystem("my-scala-microservice")
11 implicit val materializer: ActorMaterializer = ActorMaterializer()
12 implicit val executionContext: ExecutionContextExecutor = system.dispatcher
13
14 // Controller
15
16 val simpleController = new SimpleController
17
18 // Route
19
20 val route =
21 path("hello") {
22 get {
23 complete(simpleController.sayHello())
24 }
25 }
26
27 // Start the server
28
29 Http().bindAndHandle(route, "localhost", 8080)
30 println(s"Server online at http://localhost:8080/") }

d. SimpleController.scala (Controller):

Create another file called SimpleController.scala with:

1package com.mycompany  
2
3class SimpleController {
4 def sayHello(): String = "Hello, this is your first microservice with Akka HTTP!"
5}

e. Running the Microservice:

Run your microservice using sbt run. The server will start at http://localhost:8080/.

f. Testing the Route:

Open your browser or use a tool like curl to test the route:

1curl http://localhost:8080/hello 

You should see:

1Hello, this is your first microservice with Akka HTTP!

Congratulations! You've built your first Scala microservice. In the next chapters, we'll explore advanced features, testing, and deployment strategies to help you become a master in Scala microservices development. Get ready for an exciting journey!

Local Execution to Deployment

In this chapter, we'll guide you through the process of executing your Scala microservice locally using defined commands and discuss considerations for deploying it in various environments. Let's dive in!

1. Executing Microservice Locally:

Before deploying your microservice, let's make sure it runs smoothly on your local machine. Here are the steps for Linux:

a. Navigate to Your Project:

Open a terminal and navigate to your microservice project directory:

1cd path/to/your/my-scala-microservice

b. Run the Microservice:

Execute the following command to run your microservice locally:

1sbt run

This will start your microservice, and you should see output indicating that the server is online at http://localhost:8080/.

c. Test the Local Endpoint:

Open your browser or use a tool like curl to test the hello endpoint locally:

1curl http://localhost:8080/hello

You should receive the response:

1Hello, this is your first microservice with Akka HTTP!

Your microservice is now successfully running on your local machine.

2. Considerations for Deployment:

Now, let's discuss considerations for deploying your Scala microservice in various environments.

a. Packaging Your Application:

Before deploying, you need to package your application. In the root of your project, run the following command:

1sbt universal:packageZipTarball

This command creates a distribution package that you can deploy to different environments.

b. Environment-Specific Configurations:

Consider any environment-specific configurations your microservice may need. Configuration files often differ between development, testing, and production environments. Ensure your microservice is configured appropriately for the target environment.

c. Choosing a Deployment Environment:

Select the environment where you want to deploy your microservice. Common choices include:

  • Local Server: For testing and development.
  • Cloud Platforms (AWS, GCP, Azure): Scalable solutions for production.
  • Container Orchestration (Docker, Kubernetes): Efficient deployment and scaling.

d. Deploying to a Local Server:

If deploying to a local server, copy the packaged distribution to your server and extract it:

1cp target/universal/my-scala-microservice-1.0.tgz /path/to/your/server tar -xvzf my-scala-microservice-1.0.tgz

Navigate to the extracted directory and run your microservice:

1./my-scala-microservice-1.0/bin/my-scala-microservice

e. Deploying to a Cloud Platform:

For cloud deployment, you may need to upload your packaged distribution to a storage service (like Amazon S3) and deploy it on a virtual machine or containerized environment.

f. Deploying with Docker:

If using Docker, create a Dockerfile in your project root:

1FROM openjdk:11-jre-slim  
2WORKDIR /app
3COPY target/universal/my-scala-microservice-1.0.tgz .
4RUN tar -xvzf my-scala-microservice-1.0.tgz
5CMD ["./my-scala-microservice-1.0/bin/my-scala-microservice"]

Build and run the Docker image:

1docker build -t my-scala-microservice . 
2docker run -p 8080:8080 my-scala-microservice

Congratulations! You've successfully executed your Scala microservice locally and explored considerations for deploying it in different environments. Whether on a local server, a cloud platform, or within a Docker container, understanding the deployment process is crucial for bringing your microservice to a wider audience. In the next chapters, we'll explore advanced features, testing strategies, and optimization techniques to enhance your Scala microservices development skills. Get ready for the next stage of your journey!

Scala Microservices Unleashed

  • In wrapping up our exploration, you've embarked on the Scala microservices journey—from setting up your development haven to orchestrating your inaugural microservice using Akka HTTP. With routes as your guide and Akka's actor model as your co-pilot, your microservice now stands ready for the world.
  • This chapter marked your solo performance, executing your microservice locally with finesse, and contemplating the grandeur of deployment, whether on local stages, cloud platforms, or within the ballet of Docker containers.
  • As the curtain falls on this act, anticipate the encore where we delve into advanced features, finesse testing strategies, and scale the peaks of optimization. Your Scala microservices odyssey is more than a journey—it's a captivating tale of innovation and skill refinement.
  • Get ready for the next chapter, where we dive deeper into the realms of Scala microservices, revealing the secrets that elevate developers into maestros of the craft. Until then, take a bow for your first microservice creation—the stage is set for a grand encore. Bravo!