Helidon Revealed: A Practical Guide to Oracle’s Microservices Framework

This book is your comprehensive introduction to Project Helidon, Oracle’s Java-based microservices framework for building cloud-native applications. The book introduces the two flavors of Helidon—Helidon SE and Helidon MP—and shows how to quickly build applications with each one. The book begins by placing the Helidon framework in context and explaining the MicroProfile and Jakarta EE specifications that underlie the building of microservices-based applications. From there, you will learn about the individual components of Helidon SE and Helidon MP, and you will see examples of building applications for both flavors, and for MicroProfile and Jakarta EE. Finally, the book shows how to convert Helidon applications from Java bytecode into native binaries for instant application startup and peak performance. What You Will Learn Choose correctly between Helidon SE and Helidon MP Create starter applications using the Helidon SE and Helidon MP quick starts Create server and client applications with Helidon SE components Create a microservices-based application with the MicroProfile specifications Create a database application with the Jakarta NoSQL specification Generate native code with GraalVM for faster application startup time Who This Book Is For Java developers who create microservices applications; those interested in building such applications using the Helidon framework; and developers of microservices applications who want functionality such as native-image support through GraalVM, compatibility with MicroProfile, easy connectivity to database engines, and support for reactive development patterns Contents About the Author About the Technical Reviewer Chapter 1: Introduction to Project Helidon Helidon SE Functional Style Helidon MP Declarative Style (Helidon MP) Helidon Architecture Helidon Landscape Getting Started Helidon Quickstarts Helidon CLI Helidon Project Starter Helidon and the Java Community Helidon and GraalVM Helidon and Jakarta Persistence Specification Helidon and Micronaut Data Helidon and Kotlin Helidon and MicroStream Helidon and Log4j2 Improved Helidon Support in IntelliJ IDEA Release History Helidon 0.10.0 Helidon 1.0.0 Helidon 2.0.0 Helidon 3.0.0 Helidon 4.0.0 Summary Chapter 2: The MicroProfile Specifications MicroProfile Joins the Eclipse Foundation Eclipse Working Groups MicroProfile Working Group Compatible Implementations MicroProfile Release History MicroProfile 7.0 Meet the MicroProfile Specifications Jakarta Contexts and Dependency Injection (CDI) Jakarta JSON Processing (JSON-P) Jakarta RESTful Web Services (JAX-RS) Config Fault Tolerance Metrics JWT Propagation Health Open Tracing Open API Rest Client Jakarta JSON Binding (JSON-B) Jakarta Annotations Reactive Messaging Reactive Streams Operators Context Propagation GraphQL Long-Running Actions (LRA) Telemetry MicroProfile Starter Summary Chapter 3: The Jakarta EE Specifications Evolution of Java EE/Jakarta EE Eclipse Working Groups Jakarta EE Working Group Compatible Implementations Jakarta EE Profiles Platform Web Profile Core Profile Jakarta EE Release History Jakarta EE 8 Jakarta EE 9 Jakarta EE 9.1 Jakarta EE 10 Jakarta EE 11 Meet the Updated Jakarta EE Specifications Jakarta Annotations Jakarta Authentication Jakarta Authorization Jakarta Concurrency Jakarta Contexts and Dependency Injection Jakarta Data Jakarta Expression Language Jakarta Faces Jakarta Interceptors Jakarta Pages Jakarta Persistence Jakarta RESTful Web Services Jakarta Security Jakarta Servlet Jakarta Validation Jakarta WebSocket Summary Chapter 4: Creating a Small Working Project with Helidon SE Prerequisites Quickstarts Generate the Application Build the Application Initiate the Application The Client URL and JSON Pretty Printer Utilities Exercise the Application via the Command Line Exercise the Application via the Browser Server Shutdown Command-Line Interface Installation Project Starter Summary Chapter 5: Helidon WebServer WebServer Component Signature Create Method Builder Pattern Configuration Direct Configuration External Configuration Routing and HttpRouting Signature Builder Pattern Putting It All Together Dependencies Build and Execute the Application Exercising the Application Summary Chapter 6: Helidon WebClient WebClient Component Signature Create Method Builder Pattern Configuration Direct Configuration External Configuration Putting It All Together Dependencies ServerApplication Class ClientApplication Class Build and Execute the Application Exercising the Application Summary Chapter 7: Helidon Config Config Component Signature Create Method Builder Pattern Configuration Sources Signatures Configuration Loading Eagerness of Loading Data Mutability of Data Configuration Mappers Signatures Configuration Parsers Signatures Configuration Filters Signatures Loading Configuration Putting It All Together Dependencies Application Class DirectorySources Class MergeSources Class MultipleConfigSources Class Build and Execute the Application Exercising the Application Summary Chapter 8: Helidon DB Client DB Client Component Signature Create Method Builder Pattern Supporting Classes and Interfaces DbClientService DbClientMetrics DbClientHealthCheck DbClientTracing Configuration JDBC Client MongoDB Client Putting It All Together Dependencies JDBC Client MongoDB Client Configuration PokemonService Class MongoDbApplication Class Build and Execute the Application Exercising the Application Summary Chapter 9: Helidon Security Security Component Signature Create Method Builder Pattern Configuration Putting It All Together Dependencies ConfigAuthenticationApplication Class Build and Execute the Application Exercising the Application Summary Chapter 10: Creating a Small Working Project with Helidon MP Prerequisites Quickstarts Generate the Application Build the Application Initiate the Application The Client URL and JSON Pretty Printer Utilities Exercise the Application via the Command Line Exercise the Application via the Browser Server Shutdown Command-Line Interface Installation Project Starter Summary Chapter 11: Helidon Metrics Instrumenting Your Application Helidon Metrics Scopes and Corresponding REST Endpoints Base Metrics Metric Registries and the MetricRegistry API Helidon Metrics Annotations @Counted Annotation @Gauge Annotation @Timed Annotation Annotation Parameters Putting It All Together Dependencies Using the @Counted and @Timed Annotations Histogram Metric Using a Gauge Prometheus Format Build and Execute the Application Exercising the Application Summary Chapter 12: Helidon Fault Tolerance Helidon Fault Tolerance Annotations @Retry @Timeout @CircuitBreaker @Bulkhead @Fallback @Asynchronous Putting It All Together Dependencies Fallback Retry Build and Execute the Application Exercising the Application Summary Chapter 13: Helidon Health Checks Helidon Health Checks Types and REST Endpoints HealthCheck Interface Putting It All Together Dependencies System Resources System Liveness System Readiness System Startup Build and Execute the Application Exercising the Application Summary Conclusion