Pragmatica Lite - Micro Web Framework for Pragmatic Functional Java Coding Style

Minimalistic functional style micro web framework for Java 21+.

Features

• Functional style - no NPE, no exceptions, type safety, etc.
• Option/Result/Promise monads with consistent and compatible APIs.
• Simple and convenient to use Promise-based asynchronous API.
• Minimalistic - no reflection, minimal external dependencies.
• Only 3 main fully asynchronous components: HttpServer, HttpClient and PostgreSQL DB driver.
• Built-in caching domain name resolver with proper TTL handling.

Example

Some examples can be found in the examples folder.

Minimal Hello World application

import org.pragmatica.http.server.routing.Route;

import static org.pragmatica.http.server.HttpServer.with;
import static org.pragmatica.http.server.HttpServerConfig.defaultConfiguration;

/**
 * Minimal version of "Hello world" example.
 */
public static void main(String[] args) {
    with(defaultConfiguration(),
         Route.get("/")
              .toText(() -> "Hello world!"));
}

More Realistic App Skeleton

This version loads configuration from the file and is ready for adding more routes.

public class HelloWorld {
    public static void main(String[] args) {
        appConfig("server", HttpServerConfig.template())
            .flatMap(configuration -> HttpServer.with(configuration,
                                                      Route.get("/")
                                                           .toText(() -> "Hello world!")));
    }
}

Various routing examples

    //Full description
    Route.get("/hello1")
         .withoutParameters()
         .to(request -> successful(STR."Hello world! at \{request.route().path()}"))
         .as(CommonContentTypes.TEXT_PLAIN),

    //Assume no parameters
    Route.get("/hello2")
         .to(request -> successful(STR."Hello world! at \{request.route().path()}"))
         .as(CommonContentTypes.TEXT_PLAIN),

    //Assume no parameters, short content type (text)
    Route.get("/hello2")
         .to(request -> successful(STR."Hello world! at \{request.route().path()}"))
         .asText(),

    //Assume no parameters, even shorter content type (json)
    Route.get("/hello2")
         .toText(request -> successful(STR."Hello world! at \{request.route().path()}")),

    //Assume no parameters, response does not depend on request
    Route.get("/hello2")
         .toText(() -> "Hello world!"),

    //Runtime exception handling example
    Route.get("/boom-legacy")
         .toText(_ -> {
             throw new RuntimeException("Some exception message");
         }),

    //Functional error handling
    Route.get("/boom-functional")
         .toText(_ -> failed(HttpError.httpError(HttpStatus.UNPROCESSABLE_ENTITY, "Test error"))),

    //Long-running process
    Route.<NanoId, Unit>get("/delay")
         .toText(_ -> delayedResponse()),

    //Nested routes
    Route.in("/v1")
         .serve(
             Route.in("/user")
                  .serve(
                      Route.get("/list")
                           .toJson(request -> successful(request.pathParams())),
                      Route.get("/query")
                           .toJson(request -> successful(request.queryParams())),
                      Route.get("/profile")
                           .toJson(_ -> successful(new UserProfile("John", "Doe", "john.doe@gmail.com")))
                  )
         )

PostgreSQL asynchronous CRUD Repository example

(actually, there is no Update implementation)

public interface ShortenedUrlRepository {
    default Promise<ShortenedUrl> create(ShortenedUrl shortenedUrl) {
        return QRY."INSERT INTO shortenedurl (\{template().fieldNames()}) VALUES (\{template().fieldValues(shortenedUrl)}) RETURNING *"
            .in(db())
            .asSingle(template());
    }

    default Promise<ShortenedUrl> read(String id) {
        return QRY."SELECT * FROM shortenedurl WHERE id = \{id}"
            .in(db())
            .asSingle(template());
    }

    default Promise<Unit> delete(String id) {
        return QRY."DELETE FROM shortenedurl WHERE id = \{id}"
            .in(db())
            .asUnit();
    }

    DbEnv db();
}