wehub-resource-sync
191 lines
4.6 KiB
Markdown
191 lines
4.6 KiB
Markdown
# 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
|