For any profession, the tools are very important, and that applies to coding as well. Before writing a line of code, we need to get the right equipment to start.

An integrated development environment (IDE) is more than a code editor; it includes the tools for autocompletion, syntax, formatting, and other miscellaneous features, such as search and replace. IDEs have advanced features such as refactoring, building, testing, and running the programs with the help of runtime containers.

The popular IDEs are Eclipse, IntelliJ IDEA, and NetBeans. Of the three, Eclipse is the most popular and open source IDE available for Java. It has a big community and is frequently updated...

Professional software writing goes through various stages. In the following sections, we will talk about all the various stages we will follow while developing the application.

It is important to know the problem statement being solved before starting any coding or design. Agile development methodology recommends breaking the overall project into modules and services, and then implementing a few features at a time as user stories. The idea is to get a minimally viable product (MVP) and then keep adding features.

The problem we have taken to solve is an area of e-commerce. Due to online shopping, most of us are familiar with e-commerce as consumers. It is time...

Having looked at the basics, let's write our product service. After IDE setup, the next step is to select a framework to write the service. The microservice architecture puts forward a few interesting design considerations that will help us select the frameworks:

• Lightweight runtime: The service should be small in size and fast to deploy
• High resiliency: It should have support for patterns such as circuit breaker and timeout
• Measurable and monitorable: It should capture metrics and expose hooks for monitoring agents to tap into
• Efficient: It should avoid blocking resources and enable high scalability and elasticity in the presence of increased load

A good comparison can be found at: https://cdelmas.github.io/2015/11/01/A-comparison-of-Microservices-Frameworks.html. Three frameworks are gaining popularity in the Java space that meet the preceding...

For the sake of simplicity, our product service has two functions:

• List<int> getProducts(int categoryId)
• Product getProduct(int prodId)

The intent of the two methods is quite clear. The first returns a list of product IDs given a category ID, and the second returns product details (as an object) given a product ID.

Open your IDE (Eclipse Neon or other) and then create a new Maven project as follows:

1. Right-click on Package Explorer and select New and Project..., as shown in the following screenshot:

2. Select Maven Project:

3. In the next window of the wizard, choose Create a simple project.

4. The next dialog will ask for many parameters. Of these...

We have just developed a basic service with two APIs that respond to requests. Let's add a few capabilities that will enable to it to be a good cloud citizen. We will discuss the following:

• Externalizing configuration
• Instrumentation—health and metrics
• Service registration and discovery

Configuration can be any property that is likely to differ between environments or production deployments. Typical examples are queue and topic names, ports, URLs, connection and pool properties, and so on.

A deployable should not have configuration in it. A configuration should be injected from outside. This makes the deployable unit immutable as it goes through the...

Let's review the key concepts of the cloud applications that we have discussed so far. We made our application lightweight by making it run on a servlet engine and start in less than 15 seconds. Our application is self-contained, as the fat JAR has all libraries to run our service. We just need a JVM to run this JAR file. It has externalized configuration (to some extent) by injecting environment from the command line and properties from application.yml and bootstrap.yml. We take a deeper look at the next stages of externalization in Chapter 7, Cloud-Native Application Runtime. The Spring actuator helped capturing all metrics and made their URL available for consumption, thus enabling instrumentation. The location abstraction was implemented by Eureka.

In the next chapters, we will enhance this service by adding to it a data tier and resiliency...