Andreas Svanberg
a5f1b8b63e
It's a standard Spring Boot web application so far. Has automatic OpenTelemetry tracing to help debug and spot potential performance issues. Uses [Apimposter](https://gitea.dsv.su.se/DMC/apimposter) to mock out backend API dependencies. Reviewed-on: #1 Reviewed-by: Stefan Nenzén <nenzen@dsv.su.se>
31 lines
1.9 KiB
Markdown
31 lines
1.9 KiB
Markdown
# Studentportalen backend-for-frontend (BFF)
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## Development instructions
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### Prerequisites
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- [JDK 24](https://adoptium.net/temurin/releases/?version=24&package=jdk)
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- [Docker](https://docs.docker.com/desktop/)
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- [Docker Compose](https://docs.docker.com/compose/install/) (v2.24.0 or later)
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Start the application with `./mvnw spring-boot:run`. Spring will automatically run the required Docker containers.
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The application will be available at http://localhost:8080 and tracing telemetry can be viewed at http://localhost:16686.
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If running via some other means start the containers with `docker compose up`.
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Activate the Spring Boot profile "development".
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Make sure you're using the correct JVM arguments (`--enable-preview`).
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Optionally add `-javaagent:opentelemetry-javaagent.jar -Dotel.javaagent.configuration-file=opentelemetry-javaagent.properties`
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to enable OpenTelemetry tracing.
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### Preview features (`--enable-preview`)
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Due to wanting to make many concurrent calls to various backend APIs, preview features have been enabled to gain access
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to [Structured Concurrency (JEP 499)](http://openjdk.java.net/jeps/499).
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See `src/main/java/se/dsv/studentportalen/bff/TestController.java` for an example of how to use it.
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To see it in action browse to http://localhost:8080/test and check the tracing data, and you'll see that the overall
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duration is much lower than if the calls were made sequentially.
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An alternative would be to use [`CompletableFuture`](https://docs.oracle.com/en/java/javase/24/docs/api/java.base/java/util/concurrent/CompletableFuture.html)
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but that would require writing Java in a completely different style with a lot of callbacks instead of the
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imperative-looking code that Structured Concurrency offers.
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## Mocking backend APIs
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[Apimposter](https://gitea.dsv.su.se/DMC/apimposter) is used to mock the backend APIs.
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The mock data is defined in `src/mock-api`. See the linked documentation for details on how to define the mock data.
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