4.x: Update streaming example so it starts and downloads last uploade…

…d file (#8515)

* Update streaming example so it starts correctly and downloads last uploaded file
* Add tests

examples/webserver/streaming/README.md

@@ -1,9 +1,14 @@
 # Streaming Example
 
-This application uses NIO and data buffers to show the implementation of a simple streaming service.
- Files can be uploaded and downloaded in a streaming fashion using `Subscriber<DataChunk>` and 
-`Producer<DataChunk>`. As a result, service runs in constant space instead of proportional
-to the size of the file being uploaded or downloaded.
+This application is an example of a very simple streaming service. It leverages the
+fact that Helidon uses virtual threads to perform simple input/output stream blocking
+operations in the endpoint handlers. As a result, this service runs in constant space instead
+of proportional to the size of the file being uploaded or downloaded.
+
+There are two endpoints:
+
+- `upload` : uploads a file to the service
+- `download` : downloads the previously uploaded file
 
 ## Build and run
 
@@ -14,6 +19,6 @@ java -jar target/helidon-examples-webserver-streaming.jar
 
 Upload a file and download it back with `curl`:
 ```shell
-curl --data-binary "@target/classes/large-file.bin" http://localhost:8080/upload
-curl http://localhost:8080/download
+curl --data-binary "@large-file.bin" http://localhost:8080/upload
+curl http://localhost:8080/download --output myfile.bin
 ```

examples/webserver/streaming/pom.xml

@@ -55,6 +55,16 @@
             <artifactId>junit-jupiter-api</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>io.helidon.webclient</groupId>
+            <artifactId>helidon-webclient</artifactId>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>org.hamcrest</groupId>
             <artifactId>hamcrest-all</artifactId>

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, 2023 Oracle and/or its affiliates.
+ * Copyright (c) 2018, 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.
@@ -25,8 +25,6 @@
  */
 public class Main {
 
-    static final String LARGE_FILE_RESOURCE = "/large-file.bin";
-
     private Main() {
     }
 

examples/webserver/streaming/src/main/java/io/helidon/examples/webserver/streaming/StreamingService.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, 2023 Oracle and/or its affiliates.
+ * Copyright (c) 2018, 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.
@@ -18,14 +18,12 @@
 
 import java.io.IOException;
 import java.io.UncheckedIOException;
-import java.net.URISyntaxException;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.nio.file.Paths;
 import java.nio.file.StandardCopyOption;
-import java.util.Objects;
 import java.util.logging.Logger;
 
+import io.helidon.http.Status;
 import io.helidon.webserver.http.HttpRules;
 import io.helidon.webserver.http.HttpService;
 import io.helidon.webserver.http.ServerRequest;
@@ -38,14 +36,11 @@
 public class StreamingService implements HttpService {
     private static final Logger LOGGER = Logger.getLogger(StreamingService.class.getName());
 
-    private final Path filePath;
+    // Last file uploaded (or default). Since we don't do any locking
+    // when operating on the file this example is not safe for concurrent requests.
+    private volatile Path filePath;
 
     StreamingService() {
-        try {
-            filePath = Paths.get(Objects.requireNonNull(getClass().getResource(Main.LARGE_FILE_RESOURCE)).toURI());
-        } catch (URISyntaxException e) {
-            throw new RuntimeException(e);
-        }
     }
 
     @Override
@@ -59,22 +54,28 @@ private void upload(ServerRequest request, ServerResponse response) {
         try {
             Path tempFilePath = Files.createTempFile("large-file", ".tmp");
             Files.copy(request.content().inputStream(), tempFilePath, StandardCopyOption.REPLACE_EXISTING);
+            filePath = tempFilePath;
             response.send("File was stored as " + tempFilePath);
         } catch (IOException e) {
             throw new UncheckedIOException(e);
         }
-        LOGGER.info("Exiting upload ...");
+        LOGGER.info("Exiting upload after uploading " + filePath.toFile().length() + " bytes...");
     }
 
     private void download(ServerRequest request, ServerResponse response) {
         LOGGER.info("Entering download ..." + Thread.currentThread());
+        if (filePath == null) {
+            response.status(Status.BAD_REQUEST_400).send("No file to download. Please upload file first.");
+            return;
+        }
         long length = filePath.toFile().length();
         response.headers().contentLength(length);
         try {
             Files.copy(filePath, response.outputStream());
         } catch (IOException e) {
             throw new UncheckedIOException(e);
         }
-        LOGGER.info("Exiting download ...");
+        LOGGER.info("Exiting download after serving " + length + " bytes...");
     }
 }
+

examples/webserver/streaming/src/test/java/io/helidon/examples/webserver/streaming/MainTest.java

@@ -0,0 +1,93 @@
+/*
+ * 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.streaming;
+
+import io.helidon.http.Status;
+import io.helidon.webclient.http1.Http1Client;
+import io.helidon.webclient.http1.Http1ClientResponse;
+import io.helidon.webserver.http.HttpRouting;
+import io.helidon.webserver.testing.junit5.ServerTest;
+import io.helidon.webserver.testing.junit5.SetUpRoute;
+
+import org.junit.jupiter.api.MethodOrderer;
+import org.junit.jupiter.api.Order;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.TestMethodOrder;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.MatcherAssert.assertThat;
+
+@ServerTest
+@TestMethodOrder(MethodOrderer.OrderAnnotation.class)
+class MainTest {
+
+    private final Http1Client client;
+
+    private final String TEST_DATA_1 = "Test Data 1";
+    private final String TEST_DATA_2 = "Test Data 2";
+
+    protected MainTest(Http1Client client) {
+        this.client = client;
+    }
+
+    @SetUpRoute
+    static void routing(HttpRouting.Builder builder) {
+        Main.routing(builder);
+    }
+
+    @Test
+    @Order(0)
+    void testBadRequest() {
+        try (Http1ClientResponse response = client.get("/download").request()) {
+            assertThat(response.status(), is(Status.BAD_REQUEST_400));
+        }
+    }
+
+    @Test
+    @Order(1)
+    void testUpload1() {
+        try (Http1ClientResponse response = client.post("/upload").submit(TEST_DATA_1)) {
+            assertThat(response.status(), is(Status.OK_200));
+        }
+    }
+
+    @Test
+    @Order(2)
+    void testDownload1() {
+        try (Http1ClientResponse response = client.get("/download").request()) {
+            assertThat(response.status(), is(Status.OK_200));
+            assertThat(response.as(String.class), is(TEST_DATA_1));
+        }
+    }
+
+    @Test
+    @Order(3)
+    void testUpload2() {
+        try (Http1ClientResponse response = client.post("/upload").submit(TEST_DATA_2)) {
+            assertThat(response.status(), is(Status.OK_200));
+        }
+    }
+
+    @Test
+    @Order(4)
+    void testDownload2() {
+        try (Http1ClientResponse response = client.get("/download").request()) {
+            assertThat(response.status(), is(Status.OK_200));
+            assertThat(response.as(String.class), is(TEST_DATA_2));
+        }
+    }
+}