net.dbyrne.natenberg.Server.java Source code

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Here is the source code for net.dbyrne.natenberg.Server.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package net.dbyrne.natenberg;

import static java.lang.System.out;
import static javax.servlet.http.HttpServletResponse.SC_INTERNAL_SERVER_ERROR;
import static org.json.simple.JSONValue.parse;
import static org.mortbay.jetty.servlet.Context.SESSIONS;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.json.simple.JSONObject;
import org.mortbay.jetty.handler.ResourceHandler;
import org.mortbay.jetty.servlet.Context;
import org.mortbay.jetty.servlet.DefaultServlet;
import org.mortbay.jetty.servlet.ServletHolder;

import com.ericsson.otp.erlang.OtpErlangAtom;
import com.ericsson.otp.erlang.OtpErlangList;
import com.ericsson.otp.erlang.OtpErlangObject;
import com.ericsson.otp.erlang.OtpErlangPid;
import com.ericsson.otp.erlang.OtpErlangTuple;
import com.ericsson.otp.erlang.OtpMbox;
import com.ericsson.otp.erlang.OtpNode;

/**
 * Uses jinterface to relay AJAX requests/responses to an Erlang process.
 * @author Dennis Byrne
 */
public class Server {
    private OtpNode node = null;
    private final String PEER_NAME = "server@127.0.0.1";

    public static void main(String[] args) throws Exception {
        new Server().start();
    }

    private void start() throws Exception {
        node = new OtpNode("web@127.0.0.1");
        out.println(node.node() + " started w/ " + node.cookie());
        if (node.ping(PEER_NAME, 3000l)) {
            out.println(PEER_NAME + " is responsive ...");
        } else {
            node.close();
            throw new RuntimeException("Could not ping " + PEER_NAME);
        }
        org.mortbay.jetty.Server server = new org.mortbay.jetty.Server(8080);
        Context statik = new Context(server, "/", SESSIONS);
        statik.setHandler(new ResourceHandler());
        statik.setResourceBase("./src/web");
        Context root = new Context(server, "/", SESSIONS);
        root.addServlet(new ServletHolder(new JsonServelet()), "*.json");
        server.start();
        server.join();
    }

    @SuppressWarnings("serial")
    public class JsonServelet extends DefaultServlet {
        @Override
        protected void doGet(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
            OtpMbox mailbox = node.createMbox();
            String function = request.getParameter("function");
            OtpErlangTuple msg = newMsg(mailbox.self(), function);
            mailbox.send("rex", PEER_NAME, msg);
            JSONObject responseBody = null;
            try {
                OtpErlangTuple tuple = (OtpErlangTuple) mailbox.receive(3000l);
                if (tuple == null)
                    throw new NullPointerException(OtpErlangTuple.class.toString());
                String json = tuple.elementAt(1).toString();
                responseBody = (JSONObject) parse(json.substring(1, json.length() - 1));
            } catch (Exception e) {
                e.printStackTrace();
                response.setStatus(SC_INTERNAL_SERVER_ERROR);
                responseBody = newErrorMsg(e);
            }
            mailbox.close();
            response.setContentType("application/json");
            response.getWriter().print(responseBody.toJSONString());
        }
    }

    private OtpErlangTuple newMsg(OtpErlangPid returnAddress, String function) {
        return new OtpErlangTuple(
                new OtpErlangObject[] { returnAddress,
                        new OtpErlangTuple(new OtpErlangObject[] { new OtpErlangAtom("call"),
                                new OtpErlangAtom("gen_server"), new OtpErlangAtom("call"),
                                new OtpErlangList(new OtpErlangObject[] { /* args */
                                        new OtpErlangAtom("natenberg"), new OtpErlangAtom(function) }),
                                new OtpErlangAtom("user") }) });
    }

    @SuppressWarnings("unchecked")
    private JSONObject newErrorMsg(Exception e) {
        JSONObject error = new JSONObject();
        error.put("error", e.getClass() + ":" + e.getMessage());
        return error;
    }
}