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/*
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* Copyright (C) 2007 ETH Zurich
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*
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* This file is part of Fosstrak (www.fosstrak.org).
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*
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* Fosstrak is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License version 2.1, as published by the Free Software Foundation.
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*
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* Fosstrak is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Fosstrak; if not, write to the Free
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* Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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* Boston, MA 02110-1301 USA
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*/
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package org.fosstrak.epcis.utils;
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import java.io.BufferedReader;
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import java.io.IOException;
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import java.io.InputStream;
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import java.io.InputStreamReader;
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import java.io.PrintWriter;
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import java.net.ServerSocket;
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import java.net.Socket;
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import java.net.SocketException;
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import java.nio.ByteBuffer;
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import java.nio.CharBuffer;
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import java.nio.charset.Charset;
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import java.nio.charset.CharsetDecoder;
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/**
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* This class implements a simple web server listening for responses from the
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* EPCIS Query Callback interface. The server is not multi-threaded, so it will
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* only accept one request at a time. It will only allow one instance
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* (singleton) and will be bound to a predefined port on localhost.
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*
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* @author Marco Steybe
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*/
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public final class QueryCallbackListener extends Thread {
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private static final int PORT = 8899;
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private static QueryCallbackListener instance = null;
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private ServerSocket server = null;
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private boolean isRunning = false;
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private String response = null;
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/**
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* Instantiates a new SubscriptionResponseListener listening on the given
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* port.
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*
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* @throws IOException
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* If an error setting up the communication socket occurred.
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*/
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private QueryCallbackListener() throws IOException {
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System.out.println("listening for query callbacks on port " + PORT + " ...");
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server = new ServerSocket(PORT);
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}
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/**
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* @return The only instance of this class (singleton).
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* @throws IOException
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* If an error setting up the communication socket occurred.
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*/
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public static QueryCallbackListener getInstance() throws IOException {
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if (instance == null) {
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instance = new QueryCallbackListener();
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}
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return instance;
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}
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/**
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* Keeps this listener running until {@link #stopRunning()} is called.
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*
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* @see java.lang.Thread#run()
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*/
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public void run() {
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isRunning = true;
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while (isRunning) {
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Socket client = null;
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try {
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client = server.accept();
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handleConnection(client);
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} catch (SocketException e) {
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// server socket closed (stopRunning was called)
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} catch (IOException e) {
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e.printStackTrace();
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} finally {
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if (client != null) {
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try {
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client.close();
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} catch (IOException e) {
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e.printStackTrace();
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}
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}
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}
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}
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}
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/**
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* Handles an incoming HTTP connection, reading the contents, and parsing it
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* as XML.
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*
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* @param client
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* The client Socket.
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* @throws IOException
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* If an I/O error occurred.
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*/
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private void handleConnection(final Socket client) throws IOException {
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PrintWriter out = new PrintWriter(client.getOutputStream(), true);
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InputStream is = client.getInputStream();
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BufferedReader in = new BufferedReader(new InputStreamReader(is));
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// read content length
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String prefix = "content-length: ";
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String inputLine = in.readLine().toLowerCase();
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while (!inputLine.startsWith(prefix)) {
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// continue reading ...
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inputLine = in.readLine().toLowerCase();
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}
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// parse content length
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String length = inputLine.substring(prefix.length());
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int len = Integer.parseInt(length);
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inputLine = in.readLine();
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while (!inputLine.equals("")) {
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// continue reading ...
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inputLine = in.readLine();
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}
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// read, decode, and parse xml content (UTF-8 encoded!)
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byte[] xml = new byte[len];
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is.read(xml);
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ByteBuffer buf = ByteBuffer.wrap(xml);
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Charset charset = Charset.forName("UTF-8");
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CharsetDecoder decoder = charset.newDecoder();
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CharBuffer charBuffer = decoder.decode(buf);
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parseResponse(charBuffer.toString().trim());
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// write response
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out.write("HTTP/1.0 200 OK\n\n");
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out.flush();
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// notify everyone waiting on us
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synchronized (this) {
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this.notifyAll();
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}
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out.close();
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in.close();
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}
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/**
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* Extracts the XML contents from the given String.
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*
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* @param resp
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* The response from which the XML contents should be extracted.
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*/
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private void parseResponse(final String resp) {
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if (resp.startsWith("<?xml")) {
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// remove xml declaration
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int index = resp.indexOf("?>") + 2;
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if (index >= 0) {
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response = resp.substring(index).trim();
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}
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}
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}
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/**
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* @return The received XML response.
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*/
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public String fetchResponse() {
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String resp = this.response;
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this.response = null; // reset
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return resp;
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}
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/**
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* @return Wheter this thread is running.
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*/
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public boolean isRunning() {
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return isRunning;
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}
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/**
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* Stops this thread from running.
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*/
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public void stopRunning() {
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isRunning = false;
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instance = null;
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try {
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server.close();
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} catch (IOException e) {
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e.printStackTrace();
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}
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}
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}
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