New simple SSE test that shows how to use the API in Helidon SE

examples/webserver/pom.xml

@@ -53,5 +53,6 @@
         <module>tracing</module>
         <module>tutorial</module>
         <module>websocket</module>
+        <module>sse</module>
     </modules>
 </project>

examples/webserver/sse/README.md

@@ -0,0 +1,16 @@
+# Helidon SE SSE Example
+
+This example demonstrates how to use Server Sent Events (SSE) with both the WebServer and WebClient APIs.
+
+This project implements a couple of SSE endpoints that send either text or JSON messages.
+The unit test uses the WebClient API to test the endpoints.
+
+## Build, run and test
+
+Build and start the server:
+```shell
+mvn package
+java -jar target/helidon-examples-webserver-sse.jar
+```
+
+Then open http://localhost:8080 in your browser.

examples/webserver/sse/pom.xml

@@ -0,0 +1,96 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+    Copyright (c) 2024 Oracle and/or its affiliates.
+
+    Licensed under the Apache License, Version 2.0 (the "License");
+    you may not use this file except in compliance with the License.
+    You may obtain a copy of the License at
+
+        http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing, software
+    distributed under the License is distributed on an "AS IS" BASIS,
+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+    See the License for the specific language governing permissions and
+    limitations under the License.
+  -->
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+        xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <groupId>io.helidon.applications</groupId>
+        <artifactId>helidon-se</artifactId>
+        <version>4.2.0-SNAPSHOT</version>
+        <relativePath/>
+    </parent>
+    <groupId>io.helidon.examples.webserver</groupId>
+    <artifactId>helidon-examples-webserver-sse</artifactId>
+    <version>1.0.0-SNAPSHOT</version>
+    <name>Helidon Examples WebServer SSE</name>
+
+    <properties>
+        <mainClass>io.helidon.examples.webserver.sse.Main</mainClass>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>io.helidon.webserver</groupId>
+            <artifactId>helidon-webserver</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>io.helidon.webserver</groupId>
+            <artifactId>helidon-webserver-sse</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>io.helidon.webserver</groupId>
+            <artifactId>helidon-webserver-static-content</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>jakarta.json</groupId>
+            <artifactId>jakarta.json-api</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>io.helidon.http.media</groupId>
+            <artifactId>helidon-http-media-jsonp</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>io.helidon.logging</groupId>
+            <artifactId>helidon-logging-jul</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>io.helidon.webclient</groupId>
+            <artifactId>helidon-webclient-sse</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>io.helidon.webserver.testing.junit5</groupId>
+            <artifactId>helidon-webserver-testing-junit5</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.hamcrest</groupId>
+            <artifactId>hamcrest-all</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-dependency-plugin</artifactId>
+                <executions>
+                    <execution>
+                        <id>copy-libs</id>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+</project>

examples/webserver/sse/src/main/java/io/helidon/examples/webserver/sse/Main.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2024 Oracle and/or its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.helidon.examples.webserver.sse;
+
+import io.helidon.logging.common.LogConfig;
+import io.helidon.webserver.WebServer;
+import io.helidon.webserver.http.HttpRules;
+import io.helidon.webserver.staticcontent.StaticContentService;
+
+/**
+ * This application provides a simple service with a UI to exercise Server Sent Events (SSE).
+ */
+class Main {
+
+    private Main() {
+    }
+
+    /**
+     * Executes the example.
+     *
+     * @param args command line arguments, ignored
+     */
+    public static void main(String[] args) {
+        // load logging configuration
+        LogConfig.configureRuntime();
+
+        WebServer server = WebServer.builder()
+                .routing(Main::routing)
+                .port(8080)
+                .build()
+                .start();
+
+        System.out.println("WEB server is up! http://localhost:" + server.port());
+    }
+
+    /**
+     * Updates the routing rules.
+     *
+     * @param rules routing rules
+     */
+    static void routing(HttpRules rules) {
+        rules.register("/", StaticContentService.builder("WEB")
+                        .welcomeFileName("index.html")
+                        .build())
+                .register("/api", new SseService());
+    }
+}

examples/webserver/sse/src/main/java/io/helidon/examples/webserver/sse/SseService.java

@@ -0,0 +1,88 @@
+/*
+ * Copyright (c) 2024 Oracle and/or its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.helidon.examples.webserver.sse;
+
+import java.io.UncheckedIOException;
+import java.lang.System.Logger.Level;
+import java.time.Duration;
+
+import io.helidon.http.sse.SseEvent;
+import io.helidon.webserver.http.HttpRules;
+import io.helidon.webserver.http.HttpService;
+import io.helidon.webserver.http.ServerRequest;
+import io.helidon.webserver.http.ServerResponse;
+import io.helidon.webserver.sse.SseSink;
+
+import jakarta.json.spi.JsonProvider;
+
+/**
+ * SSE service.
+ */
+class SseService implements HttpService {
+
+    private static final System.Logger LOGGER = System.getLogger(SseService.class.getName());
+    private static final JsonProvider JSON_PROVIDER = JsonProvider.provider();
+
+    @Override
+    public void routing(HttpRules httpRules) {
+        httpRules.get("/sse_text", this::sseText)
+                .get("/sse_json", this::sseJson);
+    }
+
+    void sseText(ServerRequest req, ServerResponse res) throws InterruptedException {
+        int count = req.query().first("count").asInt().orElse(1);
+        int delay = req.query().first("delay").asInt().orElse(0);
+        try (SseSink sseSink = res.sink(SseSink.TYPE)) {
+            for (int i = 0; i < count; i++) {
+                try {
+                    sseSink.emit(SseEvent.builder()
+                                         .comment("comment#" + i)
+                                         .name("my-event")
+                                         .data("data#" + i)
+                                         .build());
+                } catch (UncheckedIOException e) {
+                    LOGGER.log(Level.DEBUG, e.getMessage());    // connection close?
+                    return;
+                }
+
+                if (delay > 0) {
+                    Thread.sleep(Duration.ofSeconds(delay));
+                }
+            }
+        }
+    }
+
+    void sseJson(ServerRequest req, ServerResponse res) throws InterruptedException {
+        int count = req.query().first("count").asInt().orElse(1);
+        int delay = req.query().first("delay").asInt().orElse(0);
+        try (SseSink sseSink = res.sink(SseSink.TYPE)) {
+            for (int i = 0; i < count; i++) {
+                try {
+                    sseSink.emit(SseEvent.create(JSON_PROVIDER.createObjectBuilder()
+                                                         .add("data", "data#" + i)
+                                                         .build()));
+                } catch (UncheckedIOException e) {
+                    LOGGER.log(Level.DEBUG, e.getMessage());    // connection close?
+                    return;
+                }
+
+                if (delay > 0) {
+                    Thread.sleep(Duration.ofSeconds(delay));
+                }
+            }
+        }
+    }
+}

examples/webserver/sse/src/main/java/io/helidon/examples/webserver/sse/package-info.java

@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) 2024 Oracle and/or its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Helidon Examples WebServer SSE.
+ */
+package io.helidon.examples.webserver.sse;