Http Server in Modelica

Here’s the translation of the HTTP Server example from Go to Modelica, formatted in Markdown for Hugo:

model HTTPServer
  import Modelica.Utilities.Streams;
  import Modelica.Utilities.Files;

  function hello
    input String request;
    output String response;
  algorithm
    response := "hello\n";
  end hello;

  function headers
    input String request;
    output String response;
  protected
    String[,] headerArray;
    Integer nHeaders;
  algorithm
    // Assuming we have a function to parse headers from the request
    (headerArray, nHeaders) := parseHeaders(request);
    response := "";
    for i in 1:nHeaders loop
      response := response + headerArray[i,1] + ": " + headerArray[i,2] + "\n";
    end for;
  end headers;

  function handleRequest
    input String request;
    input String path;
    output String response;
  algorithm
    if path == "/hello" then
      response := hello(request);
    elseif path == "/headers" then
      response := headers(request);
    else
      response := "404 Not Found";
    end if;
  end handleRequest;

equation
  when initial() then
    Streams.print("Server starting on port 8090...");
    // Assuming we have a function to start a server
    startServer(8090, handleRequest);
  end when;
end HTTPServer;

In Modelica, we don’t have built-in HTTP server capabilities like in some other languages. However, we can demonstrate the concept of an HTTP server using Modelica’s modeling paradigm. This example shows how we might structure an HTTP server in Modelica, focusing on the key concepts.

The HTTPServer model represents our server. It includes two functions, hello and headers, which correspond to the handlers in the original example. The handleRequest function acts as a router, directing requests to the appropriate handler based on the path.

In Modelica, we don’t have the concept of running a server in the background. Instead, we use an initial() event to start the server when the model is initialized. The startServer function is hypothetical and would need to be implemented separately, possibly using external C functions to actually create a network socket and handle HTTP requests.

To use this model:

1. Save the code in a file named HTTPServer.mo.
2. Compile and run the model using a Modelica simulation environment.

$ modelica HTTPServer.mo
Server starting on port 8090...

This example demonstrates how we might structure an HTTP server in Modelica, but it’s important to note that Modelica is primarily used for modeling physical systems and doesn’t have built-in networking capabilities. In a real-world scenario, you would typically use a language more suited for network programming to implement an HTTP server.