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Creating an Server in Flow-Wing

· 3 min read
Kushagra Rathore
Kushagra Rathore
Software Engineer

Overview​

In this tutorial, we’ll explore how to create a basic HTTP server in Flow-Wing using the Vortex module. This server will handle GET and POST requests, serving HTML and JSON content to clients. Whether you're building a simple API or serving web pages, this guide provides the foundational steps to get your Flow-Wing server up and running.

Modules Required​

To create the HTTP server, you will need to bring in the following modules:

  • Vortex: For handling HTTP requests and responses.
  • File: For reading files from the filesystem.
  • Err: For error handling.
  • Json: For parsing JSON data.
  • Map: For storing key-value pairs.

Example Code​

Here is the complete example of a simple HTTP server that serves a home page and handles JSON requests:

bring Vortex
bring File
bring Err
bring Json
bring Map

fun handleHomePage(req: Vortex::HttpRequest, res: Vortex::HttpResponse) -> nthg {
var homePage: str, homePageLoadErr: Err::Result = File::read("homePage.html", "r")    
/; Handle GET request for the home page

if (homePageLoadErr != Nir) {
  print(homePageLoadErr.getMessage(), "\n")
  res.send({
    status: 500,
    content_type: "text/html",
    body: `
    <html>
      <body>
        <h1>Error Loading Home Page</h1>
      </body>
    </html>
    `
  })
  return :
}

var err: Err::Result = res.send({
  status: 200,
  content_type: "text/html",
  body: homePage
})

if err != Nir {
  print("Error sending response: ", err.getMessage(), "\n")
}
}

fun handleGet(req: Vortex::HttpRequest, res: Vortex::HttpResponse) -> nthg {
var err: Err::Result = res.send({
  status: 200,
  content_type: "application/json",
  body: `{
    "message": "Welcome to the Flow-Wing Programming Language!"
  }`
})

if err != Nir {
  print("Error sending response: ", err.getMessage(), "\n")
}
}

fun handlePost(req: Vortex::HttpRequest, res: Vortex::HttpResponse) -> nthg {
const body: Map::String = Json::parseObject(req.body)
var name: str = body.get("name")

var err: Err::Result = res.send({
  status: 200,
  content_type: "application/json",
  body: `
     {
       "message": "Welcome to the Flow-Wing Programming Language!",
       "body": ` + body.get("name") + `
     }
     `
})
}

const port: int = 8080
print("Flow-Wing server starting on port: ", port, "\n")
var server: Vortex::Server = new Vortex::Server(port)
server.setRoute("GET", "/", handleHomePage)
server.setRoute("GET", "/api/welcome", handleGet)
server.setRoute("POST", "/", handlePost)
server.start()

Starting the Server:​

FlowWing --F=main.fg -O=-O3 --server

Server Started

Do not forget to use the --server flag

Explanation of Functions​

handleHomePage​

  • This function handles GET requests to the home page (/).
  • It attempts to read homePage.html. If successful, it sends the content with a 200 status code; otherwise, it sends a 500 error response.

handleGet​

  • This function handles GET requests to the /api/welcome endpoint.
  • It responds with a JSON message welcoming users to the Flow-Wing programming language.

handlePost​

  • This function handles POST requests to the home page (/).
  • It parses the JSON body of the request to extract the name field and responds with a JSON message that includes the name.

Starting the Server​

  • The server is initialized on port 8080.
  • Routes are defined for handling specific paths and HTTP methods.
  • The server starts listening for incoming requests.

Conclusion​

This example demonstrates how to create a basic HTTP server in Flow-Wing using the Vortex module. You can expand upon this foundation to handle more complex routing and request processing as needed.