To create a local endpoint which receives parameters like that of command line, but runs the JVM only once

TabulaServer.java

package com.company;

import technology.tabula.*;

import org.apache.commons.cli.CommandLine;
import org.apache.commons.cli.CommandLineParser;
import org.apache.commons.cli.DefaultParser;
import org.apache.commons.cli.ParseException;

import com.sun.net.httpserver.HttpExchange;
import com.sun.net.httpserver.HttpHandler;
import com.sun.net.httpserver.HttpServer;

import java.io.*;
import java.net.InetSocketAddress;
import java.net.URLDecoder;
import java.util.*;
import java.net.URI;


public class Main {

  //TODO: make this via cmd line args
  public static String IDENTITY = "fJxjt3ceM6LUhVInkTww8mmq6uOLgIse";

  // https://github.com/tabulapdf/tabula-java/blob/master/src/test/java/technology/tabula/TestCommandLineApp.java
  private static String csvFromCommandLineArgs(String[] args) throws ParseException {
    System.out.println("params: " + Arrays.toString(args));
    CommandLineParser parser = new DefaultParser();
    CommandLine cmd = parser.parse(CommandLineApp.buildOptions(), args);

    StringBuilder stringBuilder = new StringBuilder();
    new CommandLineApp(stringBuilder, cmd).extractTables(cmd);
    return stringBuilder.toString();
  }

  public static Map<String, LinkedList<String>> splitQuery(URI url) throws UnsupportedEncodingException {
    Map<String, LinkedList<String>> queryPairs = new LinkedHashMap<String, LinkedList<String>>();
    String query = url.getQuery();
    String[] pairs = query.split("&");
    for (String pair : pairs) {
      int idx = pair.indexOf("=");
      String key = URLDecoder.decode(pair.substring(0, idx), "UTF-8");
      String value = URLDecoder.decode(pair.substring(idx + 1), "UTF-8");
      if( !queryPairs.containsKey(key) ) {
        queryPairs.put(key, new LinkedList<String>());
      }
      queryPairs.get(key).add( value );
    }
    return queryPairs;
  }

  static class CommandHandler implements HttpHandler {
    @Override
    public void handle(HttpExchange t) throws IOException {

      Map<String, LinkedList<String>> queryParts = splitQuery(t.getRequestURI());

      LinkedList<String> cmdParts = new LinkedList<String>();
      for (String key : queryParts.keySet()) {
        for( String value: queryParts.get(key) ) {
          if( !key.equals("blank") ) cmdParts.add(key);
          cmdParts.add(value);
        }
      }

      String[] cmd = new String[cmdParts.size()];
      cmdParts.toArray(cmd);

      String response = null;
      int responseCode = 200;

      try{
        response = csvFromCommandLineArgs( cmd );
      }catch(ParseException pe){
        response = "ParseError: " + pe.getMessage();
        responseCode = 400;
      }

      System.out.println("response: " + response);
      t.sendResponseHeaders(responseCode, response.length());
      OutputStream os = t.getResponseBody();
      os.write(response.getBytes());
      os.close();
    }
  }

  static class IdentityHandler implements HttpHandler {
    @Override
    public void handle(HttpExchange t) throws IOException {
      String response = IDENTITY;
      t.sendResponseHeaders(200, response.length());
      OutputStream os = t.getResponseBody();
      os.write(response.getBytes());
      os.close();
    }
  }

  public static void main(String[] args) {
    try{
      int port = 8000;
      HttpServer server = HttpServer.create(new InetSocketAddress(port), 0);
      server.createContext("/execute", new CommandHandler());
      server.createContext("/identity", new IdentityHandler());
      server.setExecutor(null); // creates a default executor
      System.out.println("Listening on http://127.0.0.1:"+port);
      server.start();
    }catch(IOException pe){
      System.out.println(pe);
    }
  }

}