This project is an implementation of the SCGI protocol.

It uses Java ServerSocket to handle incoming requests and the java CachedThreadPool executor to handle them. The main entry point is the JSCGIServer class. It requires an integer as the listen port and a SCGIRequestHandler interface, which should be able to handle all expected SCGI requests.

The SCGIRequestHandler is a functional interface. It accepts an SCGIMessage instance and an OutputStream, into which the created response should be written.

The SCGIMessage is used to pass requests around. It is responsible for parsing the SCGI message from an InputStream, but it is also capable of serializing the object to an OutputStream. It holds the implementation for the SCGI protocol.

There is also an SCGIClient available which should be used to send requests to the SCGIServer. It offers several variants, how to handle the response data. It accepts either an OutputStream or can return a byte array or an SCGIMessage instance. Returning the SCGIMessage instance isn't in line with the SCGI protocol, which should return the HTTP response directly. However, using the SCGIMessage for bidirectional communication it offers a better application logic separation thus be available for custom protocol implementations as well.

The server can be created by passing the listen port and an SCGIRequestHandler implementation, where the request is an SCGIMessage instance and the response is an OutputStream.

new SCGIServer(port, (req, res) -> {
  if (req.isBodyAvailable()) {
    String name = new String(req.getBody());
    try {
      res.write(("Hello, " + name).getBytes());
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
});

The client is as simple as creating an SCGIClient instance and sending the SCGIMessage parameter to it.

SCGIClient client = new SCGIClient("localhost", port);
String response = new String(client.sendAndReceiveAsByteArray(new SCGIMessage(new HashMap<>(), "World!".getBytes()))); // Should return "Hello, World!"