Java microservices – what are they? Examples, pros and cons - Edge1S

Java microservices – what are they? Examples, pros and cons

What are microservices? Understanding of the architecture 

Microservices are a modern approach to the architecture of building complex applications. It has grown significantly in the last decade. Until the end of the 21st century, applications were mainly built with the use of monolithic architecture in which the whole app was usually built as one coherent unit.

As the projects develop and get more complex, monolithic apps have started to face flexibility, scalability and management problems.

Growing business requirements, fast development of internet technologies, and increased expectations regarding the speed of software delivery, forced companies to look for more flexible and scalable solutions.

The development of cloud services such as Amazon Web Services (AWS), Microsoft Azure and Google Cloud Platform has enabled easier scaling and management of distributed applications, and the implementation of DevOps practices (a combination of Development and Operations) has prompted the search for more automated, continuous software delivery processes . 

These events contributed to the creation of a modern application development architecture, which is based on assumptions different from the classic monolith architecture.

The definition of microservices and their difference from monolithic architecture 

Microservices is an architectural pattern for designing information systems in which an application is broken down into smaller, autonomous units called microservices.

Each microservice represents a distinct business function and operates as an independent entity, communicating with other services using APIs. Microservices are modular, which makes it easier to manage, develop, test and maintain the system. A key feature is independence, both in terms of implementation and technology, which allows for flexibility and scalability of the system.

Microservices allow you to better control the level of technical debt, reduce the risk of stopping the entire system due to a small error in one area, enable faster and more frequent implementation of new versions, and also increase system stability. 


The biggest differences between monolithic architecture and microservices include:

Application size and structure 

  • Monolithic architecture – one, usually large application in which all functions are integrated and available in one place. 
  • Microservices – breaking down applications into smaller, independent units representing specific functions. 

The way components communicate

  • Monolithic architecture – all application components run in one process, sharing the same resources and data. 
  • Microservices – communication between services takes place via API interfaces, which enables communication in a distributed environment. 

Application scaling 

  • Monolithic architecture – scaling involves increasing the instances of the entire application, even if only some of it needs additional resources. 
  • Microservices – individual services can be scaled independently, which allows resources to be adjusted only for specific functions. 

Flexibility in updating 

  • Monolithic architecture – updates usually require stopping the entire application. 
  • Microservices – updates can be implemented independently for individual services, which minimizes the impact on the entire system. 

Project management method 

  • Monolithic architecture – one programming group responsible for the entire application. 
  • Microservices – different teams can be responsible for different microservices, making project management easier.

Malfunction tolerance 

  • Monolithic architecture – the failure of one part can affect the entire application. 
  • Microservices – isolation allows other services to work despite the failure of one of them. 

Advantages of using microservices in Java

Using microservices in Java can bring many benefits, both from a developer and business perspective.

Scalability and independence of components 

The use of microservices in Java allows for high scalability and the use of component independence. 

In microservices, individual services can be scaled independently. If a particular microservice requires additional resources due to workload, it can be scaled without affecting the others. Java, due to the JVM (Java Virtual Machine) platform, allows you to easily add new service instances on different machines in a flexible and efficient way. 

Microservices in Java can be scaled both horizontally (adding further instances of microservices) and vertically (increasing the resources available for a particular microservice). This approach provides flexibility in adapting the system to changing loads. 

Java works well with container technologies such as Docker, which facilitates container portability and management. Additionally, orchestration tools such as Kubernetes allow for coordinated management of multiple microservice instances. 

Java is a programming language that has long supported code modularization. Using mechanisms such as the Java Platform Module System (JPMS), you can easily create independent modules representing microservices. 

Examples of successful microservices implementations 

The largest companies in the e-commerce, banking, telecommunications and entertainment sectors use microservices architecture to build applications. The advantages of using microservices are best seen in large, complex applications that must maintain operational continuity and a high SLA level. What do microservices look like in action?

The most popular examples of successful microservices implementations include companies such as: 

  • Netflix – the popular streaming platform is built on the basis of many small and independent services, and most of them are written in Java, using the Spring Boot framework. 
  • Allegro – the largest e-commerce player in Poland, abandoned monolithic architecture in favor of microservices to better adapt to the growing number of users and increase development flexibility. 
  • – Booking – one of the largest booking platforms in the world – also uses microservices. 
  • Spotify – a popular music streaming platform also uses microservices. Their system is built of many autonomous services, and Java is one of the programming languages used to implement these services. 


Disadvantages of microservices – Potential traps and how to avoid them 

The use of microservices undoubtedly has a number of advantages that are desirable in today’s highly digitized and rapidly changing world. However, you should know that microservices also have their disadvantages. The advantages and disadvantages of microservices result directly from their architecture. These include, among others,: 

  • Complex testing 
  • The need to manage versions and maintain compatibility 
  • Coordination of a large number of small websites 

Comprehensiveness of management and integration 

One of the main disadvantages of microservices is the complexity of management and integration.

Microservices often require complex mechanisms for communicating with each other. The need to manage different protocols, data formats and synchronize operations can introduce additional complexity. 

Microservice integration often involves creating and maintaining appropriate APIs. Managing different interface versions, their compatibility and evolution becomes complicated, especially in the case of numerous websites. 

In a microservices environment, both consumer and server sides must be constantly updated to maintain interface compatibility. Managing this process and ensuring that both parties are always on the same page can be difficult. 

As microservices evolve, APIs change. Managing interface versions for backward compatibility requires precise planning and monitoring, which can be tedious. 

Each microservice may require different configuration settings. Managing configuration for multiple microservices can become difficult and time-consuming. 

In microservices, failures in communication between services can lead to problems with data availability and consistency. Communication reliability is becoming a key aspect of microservices management.

As the number of microservices increases, scaling the system becomes more complex. The need to balance loads, monitor performance, and coordinately manage multiple sites requires advanced tools and strategies. 

To avoid complex management and integration issues with microservices, it’s important to carefully plan, document, and monitor APIs, use configuration management automation tools, implement version control, and apply microservice management best practices. 


Basic components of microservices architecture 

A microservices architecture consists of many components, each of which plays its own role in a decentralized system. The basic components of microservices architecture include: 

  • Microservices 
  • APIs 
  • Configuration management 
  • Service register 
  • Load Balancers 
  • Database 
  • Monitoring and logging tools 
  • CI/CD tools 
  • Container management 
  • Version management 

These components interact with each other to create a flexible and scalable microservices system. Their effective management and integration require careful planning and the use of appropriate tools and practices.

How to prepare an application example in Java microservices? 

Preparing a sample application in Java microservices requires a preparation process. As part of it, you need to go through several steps that will allow you to efficiently create the application. These include:  

  • Determining the functionality of the application  
  • Selection of frameworkworks and tools  
  • Microservices implementation  
  • Configuration and environment management  
  • Managing communication between microservices  
  • Application testing process  
  • Application implementation 
  • Monitoring, diagnostics and ongoing application support 

Creating a microservice in Java Spring step by step 

After preparing to create a microservice in Java, you can proceed to the application development process, which consists of the following stages: 

  • Preparing the environment 
  •  Creating a microservice in a prepared environment 
  •  Starting the microservice 
  •  Adding dependencies to the database 
  •  Scaling the created microservice 
  •  Conducting tests 
  •  Deployment of the created microservice to production

The above steps are the basic tasks that need to be performed to build a microservice in Java Spring. Once done, remember that implementing microservices also requires proper configuration management, monitoring, and maintenance. 


Communication between microservices – protocols and patterns 

REST, gRPC and asynchronous communication 

REST, gRPC and asynchronous communication are different approaches to designing systems and communicating between services. 

REST (Representational State Transfer) is an architectural style that defines certain principles such as statelessness, resource as a state representation, uniform interface, and separation of client and server. 

  •  Communication protocol – HTTP 
  •  Data formats – JSON or XML 
  •  Communication – asynchronous 


gRPC (gRPC Remote Procedure Call) is a framework developed by Google, based on the HTTP/2 protocol. Enables remote procedure calling (RPC) between sites. 

  • Communication protocol – HTTP/2 
  • Data formats – binary data format, e.g. JSON 
  • Communication – synchronous and asynchronous 


Asynchronous communication involves sending messages between services without waiting for an immediate response. This approach is particularly useful for operations that may take a long time or when services do not have to wait for a response. 

In practice, the choice between REST, gRPC and asynchronous communication depends on the requirements of the project, and often microservice systems use a combination of these approaches depending on the specifics of a given use case. 

Java microservices in practice – tools and frameworks

Microservices architecture uses various tools and frameworks to facilitate  the implementation, management, monitoring, and testing of microservices. 

Spring Boot, Micronaut andQuarkus 

Spring Boot, Micronaut and Quarkus are three popular frameworks used in the context of building microservices in Java. Each of these frameworks has its own unique features and advantages. Below we present their brief characteristics.  

Spring Boot is one of the most popular tools for creating microservices in Java. It is part of the Spring ecosystem, which provides extensive tools for building various types of applications. 

Spring Boot advantages:  

  • Rich support for dependency injection (DI). 
  • A large number of modules to facilitate application development, such as Spring Security, Spring Data, Spring Cloud, etc. 
  • Active community and great documentation support. 
  • Relatively simple to learn, especially for developers with experience in the Spring ecosystem. 

Spring Boot usage examples: 

  • Extensive corporate systems 
  • Web applications 


Micronaut is a framework designed to build light, fast and effective microservices in Java. It is compatible with Java microservices, Kotlin and Groovy. 

Micronaut advantages: 

  • Low memory usage and fast startup time.  
  • Dependency injection and code generation occur at compile time, which contributes to operational efficiency.  
  • Support for many Java libraries and standards. 

Micronaut application examples: 

  • Serverless applications 
  • Real-time applications 


Quarkus is a dedicated Java framework designed to build optimized applications, especially in containers and the cloud. 

Quarkus advantages: 

  • Very short startup time and low memory consumption. 
  • Optimized for container environments, which makes it ideal for microservices. 
  • Support for multiple Java standards and integration with the Quarkus Extensions ecosystem. 

Quarkus application examples:  

  • Features of serverless applications 
  • Cloud applications 

Microservices security – authentication and authorization 

Microservice security is a key aspect in the design and implementation of systems based on microservice architecture. Authentication and authorization are the two main elements that protect microservices against access by unauthorized users.

Authentication is the process of confirming the identity of a user, application or system. In the context of microservices, authentication is necessary to ensure that the person or component attempting to access system resources is who they claim to be. 

Authorization determines what activities or resources a given identity is allowed to perform or access. In microservices, it is important to precisely manage permissions to avoid unauthorized access to resources.

It is worth noting that effective authentication and authorization management in microservices requires a holistic approach, taking into account both authentication mechanisms and appropriate access policies. 

Security strategies and implementation of OAuth 2.0 

Implementing OAuth 2.0 in microservices covers several key aspects: 

  • Secure token transfer 
  • Granting limited permissions 
  • Secure token storage 
  • Identification and authentication 
  • Protection of customer data 
  • Protection against CSRF attacks 
  • Implementation of access control mechanisms 

Carrying out an effective implementation of Oauth 2.0 in microservices requires: 

  • Registration of the client application 
  • Implementation of the authentication process 
  • Token generation and verification 
  • Security against attacks 
  • Integration with access control mechanisms 
  • Monitoring and logging 
  • Regular updates and audits 


The implementation of OAuth 2.0 in microservices requires strict compliance with security standards and taking into account the specificity of microservice architecture. Taking care of each of the above-mentioned aspects will allow you to effectively protect the system against potential threats. 


Microservices testing – how to ensure code reliability? 

Microservices testing is a key element of the software development process and its goal is to ensure the reliability, performance and correctness of microservices functions. 

Unit, integration and contract tests  

The most popular strategies and practices for ensuring the reliability of microservices code include unit testing, integration testing, and contract testing. 

Unit tests verify that individual components or code functions work correctly. They are performed at the lowest level of abstraction, at the level of individual classes, functions or methods. They are characterized by speed of execution and easy automation. They are good for testing the correct operation of an isolated unit of code. 

Integration tests verify the correct cooperation between various components or microservices. They focus on the interaction between components. They check whether the integration of various code units is as expected and help detect potential problems related to communication between microservices. 

Contract tests are used to verify the compliance of agreements (contracts) between microservices. They focus on verifying communication interfaces between microservices. They verify that microservices adhere to established communication agreements and enable the identification of potential conflicts between the interface producer and consumer. 

In complex microservice systems, focusing on these three types of testing while ensuring automation and continuous integration helps maintain the reliability and correctness of the functions of each microservice and secure the integrity of the interactions between them. 


Microservices deployment – from containers to orchestration 

The microservice deployment process includes implementing and running a microservice application in a production environment. In a microservices environment, popular deployment approaches include the use of containers and container orchestration. 

Docker, Kubernetes and their role in microservices 

Docker and Kubernetes are popular tools in the containerization and orchestration ecosystem that play a key role in the implementation of microservices. Docker is used for containerization and Kubernetes for container orchestration. 

Docker enables application containerization, which means that each microservice is wrapped in a lightweight, portable container. Containers contain the application, dependencies, and configuration, isolating them from the environment in which they run. With Docker, you can ensure a uniform environment, which eliminates the problems associated with differences between development, test and production environments. Developers working on different microservices can use the same containers. Docker makes it easy to deploy microservices across different environments, which speeds up the application lifecycle from development to production. Docker containers provide isolation, which means that each microservice runs independently without affecting other microservices. This enables scalability and increases system reliability. 

Kubernetes is an advanced container orchestration tool. Manages the lifecycle of containers, their replication, scaling, monitoring and disaster recovery. Kubernetes allows you to easily scale microservices depending on your workload. Automatic addition or removal of containers ensures flexibility and resource efficiency. Kubernetes ensures high application availability through automatic replication and load balancing. In the event of a failure, new instances of microservices are automatically launched. The configuration of microservices in Kubernetes is saved in a declarative form, which makes it easy to manage and update the configuration without interrupting the operation of the system. Kubernetes offers built-in monitoring and logging mechanisms, making it easy to track performance and identify possible issues with your microservices. Kubernetes allows you to distribute traffic between different versions of microservices, which allows for smooth deployments and updates without interrupting application performance. 

Docker and Kubernetes together create powerful tools for building, deploying, and managing microservices. Docker provides a unified container environment, while Kubernetes offers advanced orchestration features, allowing you to effectively manage and scale microservices in a dynamic and demanding production environment. The cooperation of these two tools contributes to the effective implementation and maintenance of microservice architecture. 

Monitoring and logging in Java microservices

Java microservices monitoring and logging are important to maintaining the ability to track, diagnose, and optimize system performance and stability.

By monitoring and logging in microservices, it is possible to identify and solve problems and optimize performance. The combination of effective metrics, monitoring, and logging is an important part of keeping your microservices healthy. 

Tracking and diagnostic tools 

Dedicated applications are used to track and diagnose microservices. There are many tools to help with these tasks. Below are some popular tracking and diagnostic tools in the context of microservices. 

Tracking tools: 

  • Zipkin  
  • Jaeger  
  • OpenTelemetry  

Diagnostic tools: 

  • Spring Boot Actuator 
  • Micrometer 
  • Prometheus 
  • New Relic 
  • Dynatrace  


The future of microservices – trends and directions of development

The IT environment is incredibly dynamic, and the trends and development directions of microservices are evolving rapidly. Currently, the most popular development trends that will be used in the future are microservers in the cloud and the use of the serverless approach. 

Cloud and severless microservices 

Cloud microservices is an approach in which microservices-based applications are hosted and managed in a cloud environment. Using the cloud to implement microservices introduces a number of benefits related to flexibility, scalability, availability and services offered by cloud providers. 

Serverless Computing is an approach to building and deploying applications in which the infrastructure is managed automatically by the cloud provider. Microservices can use serverless to focus on the code and not worry about infrastructure. In this model, resources are dynamically allocated and the basic unit is a function (serverless function). The main features of serverless are the lack of the need to maintain servers, automatic scaling and payment only for the actual use of resources. Serverless is especially attractive for projects that require flexibility, scalability and quick implementation times. 

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