chore: import upstream snapshot with attribution

03-GettingStarted/06-http-streaming/solution/java/README.md

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+# Calculator HTTP Streaming Demo
+
+This project demonstrates HTTP streaming using Server-Sent Events (SSE) with Spring Boot WebFlux. It consists of two applications:
+
+- **Calculator Server**: A reactive web service that performs calculations and streams results using SSE
+- **Calculator Client**: A client application that consumes the streaming endpoint
+
+## Prerequisites
+
+- Java 17 or higher
+- Maven 3.6 or higher
+
+## Project Structure
+
+```
+java/
+├── calculator-server/     # Spring Boot server with SSE endpoint
+│   ├── src/main/java/com/example/calculatorserver/
+│   │   ├── CalculatorServerApplication.java
+│   │   └── CalculatorController.java
+│   └── pom.xml
+├── calculator-client/     # Spring Boot client application
+│   ├── src/main/java/com/example/calculatorclient/
+│   │   └── CalculatorClientApplication.java
+│   └── pom.xml
+└── README.md
+```
+
+## How It Works
+
+1. The **Calculator Server** exposes a `/calculate` endpoint that:
+   - Accepts query parameters: `a` (number), `b` (number), `op` (operation)
+   - Supported operations: `add`, `sub`, `mul`, `div`
+   - Returns Server-Sent Events with calculation progress and result
+
+2. The **Calculator Client** connects to the server and:
+   - Makes a request to calculate `7 * 5`
+   - Consumes the streaming response
+   - Prints each event to the console
+
+## Running the Applications
+
+### Option 1: Using Maven (Recommended)
+
+#### 1. Start the Calculator Server
+
+Open a terminal and navigate to the server directory:
+
+```bash
+cd calculator-server
+mvn clean package
+mvn spring-boot:run
+```
+
+The server will start on `http://localhost:8080`
+
+You should see output like:
+```
+Started CalculatorServerApplication in X.XXX seconds
+Netty started on port 8080 (http)
+```
+
+#### 2. Run the Calculator Client
+
+Open a **new terminal** and navigate to the client directory:
+
+```bash
+cd calculator-client
+mvn clean package
+mvn spring-boot:run
+```
+
+The client will connect to the server, perform the calculation, and display the streaming results.
+
+### Option 2: Using Java directly
+
+#### 1. Compile and run the server:
+
+```bash
+cd calculator-server
+mvn clean package
+java -jar target/calculator-server-0.0.1-SNAPSHOT.jar
+```
+
+#### 2. Compile and run the client:
+
+```bash
+cd calculator-client
+mvn clean package
+java -jar target/calculator-client-0.0.1-SNAPSHOT.jar
+```
+
+## Testing the Server Manually
+
+You can also test the server using a web browser or curl:
+
+### Using a web browser:
+Visit: `http://localhost:8080/calculate?a=10&b=5&op=add`
+
+### Using curl:
+```bash
+curl "http://localhost:8080/calculate?a=10&b=5&op=add" -H "Accept: text/event-stream"
+```
+
+## Expected Output
+
+When running the client, you should see streaming output similar to:
+
+```
+event:info
+data:Calculating: 7.0 mul 5.0
+
+event:result
+data:35.0
+```
+
+## Supported Operations
+
+- `add` - Addition (a + b)
+- `sub` - Subtraction (a - b)
+- `mul` - Multiplication (a * b)
+- `div` - Division (a / b, returns NaN if b = 0)
+
+## API Reference
+
+### GET /calculate
+
+**Parameters:**
+- `a` (required): First number (double)
+- `b` (required): Second number (double)
+- `op` (required): Operation (`add`, `sub`, `mul`, `div`)
+
+**Response:**
+- Content-Type: `text/event-stream`
+- Returns Server-Sent Events with calculation progress and result
+
+**Example Request:**
+```
+GET /calculate?a=7&b=5&op=mul HTTP/1.1
+Host: localhost:8080
+Accept: text/event-stream
+```
+
+**Example Response:**
+```
+event: info
+data: Calculating: 7.0 mul 5.0
+
+event: result
+data: 35.0
+```
+
+## Troubleshooting
+
+### Common Issues
+
+1. **Port 8080 already in use**
+   - Stop any other applications using port 8080
+   - Or change the server port in `calculator-server/src/main/resources/application.yml`
+
+2. **Connection refused**
+   - Make sure the server is running before starting the client
+   - Check that the server started successfully on port 8080
+
+3. **Parameter name issues**
+   - This project includes Maven compiler configuration with `-parameters` flag
+   - If you encounter parameter binding issues, ensure the project is built with this configuration
+
+### Stopping the Applications
+
+- Press `Ctrl+C` in the terminal where each application is running
+- Or use `mvn spring-boot:stop` if running as a background process
+
+## Technology Stack
+
+- **Spring Boot 3.3.1** - Application framework
+- **Spring WebFlux** - Reactive web framework
+- **Project Reactor** - Reactive streams library
+- **Netty** - Non-blocking I/O server
+- **Maven** - Build tool
+- **Java 17+** - Programming language
+
+## Next Steps
+
+Try modifying the code to:
+- Add more mathematical operations
+- Include error handling for invalid operations
+- Add request/response logging
+- Implement authentication
+- Add unit tests

03-GettingStarted/06-http-streaming/solution/java/calculator-client/pom.xml

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+<project>
+  <modelVersion>4.0.0</modelVersion>
+  <groupId>com.example</groupId>
+  <artifactId>calculator-client</artifactId>
+  <version>0.0.1-SNAPSHOT</version>
+
+  <properties>
+    <java.version>17</java.version>
+    <spring.boot.version>3.3.1</spring.boot.version>
+  </properties>
+
+  <dependencyManagement>
+    <dependencies>
+      <dependency>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-dependencies</artifactId>
+        <version>${spring.boot.version}</version>
+        <type>pom</type>
+        <scope>import</scope>
+      </dependency>
+    </dependencies>
+  </dependencyManagement>
+
+  <dependencies>
+    <!-- Spring Boot WebFlux for WebClient -->
+    <dependency>
+      <groupId>org.springframework.boot</groupId>
+      <artifactId>spring-boot-starter-webflux</artifactId>
+    </dependency>
+  </dependencies>
+
+  <build>
+    <plugins>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-compiler-plugin</artifactId>
+        <version>3.11.0</version>
+        <configuration>
+          <source>${java.version}</source>
+          <target>${java.version}</target>
+          <parameters>true</parameters>
+        </configuration>
+      </plugin>
+      <plugin>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-maven-plugin</artifactId>
+      </plugin>
+    </plugins>
+  </build>
+</project>

03-GettingStarted/06-http-streaming/solution/java/calculator-client/src/main/java/com/example/calculatorclient/CalculatorClientApplication.java

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+package com.example.calculatorclient;
+
+import org.springframework.boot.CommandLineRunner;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.http.MediaType;
+import org.springframework.web.reactive.function.client.WebClient;
+
+@SpringBootApplication
+public class CalculatorClientApplication implements CommandLineRunner {
+
+    private final WebClient client = WebClient.builder()
+            .baseUrl("http://localhost:8080")
+            .build();
+
+    public static void main(String[] args) {
+        SpringApplication.run(CalculatorClientApplication.class, args);
+    }
+
+    @Override
+    public void run(String... args) {
+        client.get()
+                .uri(uriBuilder -> uriBuilder
+                        .path("/calculate")
+                        .queryParam("a", 7)
+                        .queryParam("b", 5)
+                        .queryParam("op", "mul")
+                        .build())
+                .accept(MediaType.TEXT_EVENT_STREAM)
+                .retrieve()
+                .bodyToFlux(String.class)
+                .doOnNext(System.out::println)
+                .blockLast();
+    }
+}

03-GettingStarted/06-http-streaming/solution/java/calculator-client/src/main/resources/application.yml

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+spring:
+  main:
+    web-application-type: none

03-GettingStarted/06-http-streaming/solution/java/calculator-server/pom.xml

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+<project>
+  <modelVersion>4.0.0</modelVersion>
+  <groupId>com.example</groupId>
+  <artifactId>calculator-server</artifactId>
+  <version>0.0.1-SNAPSHOT</version>
+
+  <properties>
+    <java.version>17</java.version>
+    <spring.boot.version>3.3.1</spring.boot.version>
+  </properties>
+
+  <dependencyManagement>
+    <dependencies>
+      <dependency>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-dependencies</artifactId>
+        <version>${spring.boot.version}</version>
+        <type>pom</type>
+        <scope>import</scope>
+      </dependency>
+    </dependencies>
+  </dependencyManagement>
+
+  <dependencies>
+    <!-- Spring Boot WebFlux for SSE -->
+    <dependency>
+      <groupId>org.springframework.boot</groupId>
+      <artifactId>spring-boot-starter-webflux</artifactId>
+    </dependency>
+  </dependencies>
+
+  <build>
+    <plugins>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-compiler-plugin</artifactId>
+        <version>3.11.0</version>
+        <configuration>
+          <source>${java.version}</source>
+          <target>${java.version}</target>
+          <parameters>true</parameters>
+        </configuration>
+      </plugin>
+      <plugin>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-maven-plugin</artifactId>
+      </plugin>
+    </plugins>
+  </build>
+</project>

03-GettingStarted/06-http-streaming/solution/java/calculator-server/src/main/java/com/example/calculatorserver/CalculatorController.java

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+package com.example.calculatorserver;
+
+import java.time.Duration;
+
+import org.springframework.http.MediaType;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.bind.annotation.RestController;
+
+import reactor.core.publisher.Flux;
+import org.springframework.http.codec.ServerSentEvent;
+
+@RestController
+public class CalculatorController {
+
+    @GetMapping(value = "/calculate", produces = MediaType.TEXT_EVENT_STREAM_VALUE)
+    public Flux<ServerSentEvent<String>> calculate(@RequestParam double a,
+                                                   @RequestParam double b,
+                                                   @RequestParam String op) {
+
+        double result;
+        switch (op) {
+            case "add":
+                result = a + b;
+                break;
+            case "sub":
+                result = a - b;
+                break;
+            case "mul":
+                result = a * b;
+                break;
+            case "div":
+                result = b != 0 ? a / b : Double.NaN;
+                break;
+            default:
+                result = Double.NaN;
+        }
+
+        return Flux.<ServerSentEvent<String>>just(
+                    ServerSentEvent.<String>builder()
+                        .event("info")
+                        .data("Calculating: " + a + " " + op + " " + b)
+                        .build(),
+                    ServerSentEvent.<String>builder()
+                        .event("result")
+                        .data(String.valueOf(result))
+                        .build()
+                )
+                .delayElements(Duration.ofSeconds(1));
+    }
+}

03-GettingStarted/06-http-streaming/solution/java/calculator-server/src/main/java/com/example/calculatorserver/CalculatorServerApplication.java

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+package com.example.calculatorserver;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class CalculatorServerApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(CalculatorServerApplication.class, args);
+    }
+}

03-GettingStarted/06-http-streaming/solution/java/calculator-server/src/main/resources/application.yml

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+server:
+  port: 8080