How do I create an asynchronous REST endpoint in Microserver?

Return a reactive-streams Publisher from your endpoint method, such as a Future from cyclops-react, and Microserver automatically handles async execution. For example, the README shows returning 'Future ' to make the endpoint non-blocking.

Microserver vs Spring Boot for Java microservices?

Microserver offers zero configuration and a plugin-based approach, ideal for teams wanting lightweight control without Spring Boot's opinionated defaults. However, Spring Boot has a larger ecosystem and more built-in features, making it better for rapid development with less custom setup.

How to embed multiple microservices in one JVM with Microserver?

Use the EmbeddedModule class when starting MicroserverApp, specifying different REST resource classes and contexts for each service. The README example shows colocating 'test-app' and 'alternative-app' by passing multiple EmbeddedModule instances.

What plugins are available for Microserver?

Core plugins include integrations for Spring, Jersey, Tomcat, Grizzly, Hibernate, Swagger, and reactive programming. You can add them via Maven or Gradle dependencies, and the plugin list is extensible for custom needs.

How to configure application properties in Microserver?

Microserver auto-discovers 'application.properties' from the classpath or file system, with support for environment-specific files via system properties. You can also override properties programmatically using the Module interface or custom plugins.

Does Microserver support WebSockets or only REST?

The README focuses on REST endpoints with async NIO support, but WebSocket compatibility isn't explicitly mentioned. For real-time features, you might need to check plugin availability or implement custom solutions, as it's primarily designed for REST microservices.

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Microserver

Apache-2.0Javav1.2.6

A zero-configuration Java 8 library for building and running REST microservices with a plugin-based architecture.

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What is Microserver?

Microserver is a Java 8 native library for building and running REST microservices with zero configuration and a plugin-based architecture. It provides a standards-based, battle-hardened engine that supports both pure microservices and micro-monolith styles, allowing teams to adopt microservices without operational risk. The library simplifies service development by eliminating XML configuration and imposing no directory structure.

Target Audience

Java developers and teams building REST microservices who want a lightweight, modular alternative to heavier frameworks like Spring Boot, especially those transitioning from monoliths to microservices.

Value Proposition

Developers choose Microserver for its zero-configuration setup, plugin-driven modularity, and support for micro-monolith deployments, which offer the productivity of microservices without the operational overhead. Its battle-tested production use since 2014 and seamless integration with popular Java ecosystems like Spring and Jersey make it a reliable choice.

Overview

Microserver is a Java 8 native, zero configuration, standards based, battle hardened library to run Java Rest Microservices via a standard Java main class. Supporting pure Microservice or Micro-monolith styles.

Use Cases

Best For

Building zero-configuration REST microservices in Java
Transitioning from monolithic applications to microservices without full operational risk
Developing micro-monoliths where multiple services are packaged into a single deployment
Integrating with Spring, Jersey, Tomcat, or Grizzly via plugins
Creating asynchronous REST endpoints using reactive-streams Publishers
Embedding and colocating multiple microservices within a single JVM

Not Ideal For

Teams deeply embedded in Spring Boot's ecosystem who prefer its convention-over-configuration defaults and extensive starter packs
Projects requiring out-of-the-box support for serverless or cloud-native platforms like Kubernetes, as Microserver focuses on traditional JVM deployments
Applications needing polyglot microservices or integration with non-Java technologies, since Microserver is Java-specific

Pros & Cons

Pros

Zero Configuration Simplicity

Requires no XML or imposed directory structure; you can start a REST service with just a Java main class, as shown in the quick start example where 'new MicroserverApp(() -> "test-app").run()' deploys a server.

Flexible Plugin Ecosystem

Seamlessly integrates with Spring, Jersey, Tomcat, and more via modular plugins, allowing teams to add features like Swagger or Hibernate by simply adding dependencies to the build file.

Micro-Monolith Deployment Support

Enables packaging multiple services into a single deployment for developer productivity, helping teams transition from monoliths to microservices without full operational risk, as detailed in the embedded microservices example.

Built-in Async REST

Automatically executes endpoints asynchronously by returning reactive-streams Publishers, simplifying async programming without manual AsyncResponse handling, demonstrated with Future from cyclops-react.

Cons

Plugin Dependency Management

The plugin architecture requires careful management of dependencies and service aggregation in fat Jars, as noted in the README's warning to configure tools like Gradle Shadow Jar with 'mergeServiceFiles()'.

Embedded Service Complexity

Colocating multiple microservices in one JVM demands caution to avoid conflicts in the shared Spring context, increasing setup complexity compared to isolated deployments.

Limited Ecosystem Compared to Spring Boot

While plugins cover popular tools, the ecosystem is smaller than Spring Boot's, potentially missing integrations for newer or niche technologies, forcing custom plugin development.

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