source: trunk/EventBenchConsole/src/de/ugoe/cs/eventbench/web/WeblogParser.java @ 176

package de.ugoe.cs.eventbench.web;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

import de.ugoe.cs.eventbench.web.data.WebEvent;
import de.ugoe.cs.util.FileTools;
import de.ugoe.cs.util.console.Console;

/**
 * <p>
 * Provides functionality to parse log files with web request.
 * </p>
 * 
 * @author Steffen Herbold
 * @version 1.0
 */
public class WeblogParser {

        /**
         * <p>
         * Timeout between two sessions in milliseconds.
         * </p>
         */
        private long timeout;

        /**
         * <p>
         * Minimal length of a session. All shorter sessions will be pruned.
         * Default: 2
         * </p>
         */
        private int minLength = 2;

        /**
         * <p>
         * Collection of generated sequences.
         * </p>
         */
        private List<List<WebEvent>> sequences;

        /**
         * <p>
         * Name and path of the robot filter.
         * </p>
         */
        private static final String ROBOTFILTERFILE = "misc/robotfilter.txt";

        /**
         * <p>
         * Field that contains a regular expression that matches all robots
         * contained in {@link #ROBOTFILTERFILE}.
         * </p>
         */
        private String robotRegex = null;

        /**
         * <p>
         * Constructor. Creates a new WeblogParser with a default timeout of
         * 3,600,000 milliseconds (1 hour).
         * </p>
         */
        public WeblogParser() {
                this(3600000);
        }

        /**
         * <p>
         * Constructor. Creates a new WeblogParser.
         * </p>
         * 
         * @param timeout
         *            session timeout
         */
        public WeblogParser(long timeout) {
                this.timeout = timeout;
        }

        /**
         * <p>
         * Returns the generated event sequences.
         * </p>
         * 
         * @return generated event sequences
         */
        public List<List<WebEvent>> getSequences() {
                return sequences;
        }

        /**
         * <p>
         * Sets the session timeout.
         * </p>
         * 
         * @param timeout
         *            new session timeout
         */
        public void setTimeout(long timeout) {
                this.timeout = timeout;
        }

        /**
         * <p>
         * Sets the minimal length of a session. All sessions that contain less
         * events will be pruned.
         * </p>
         * 
         * @param minLength
         *            new minimal length
         */
        public void setMinLength(int minLength) {
                this.minLength = minLength;
        }

        /**
         * <p>
         * Parses a web log file.
         * </p>
         * 
         * @param filename
         *            name and path of the log file
         * @throws IOException
         *             thrown if there is a problem with reading the log file
         * @throws FileNotFoundException
         *             thrown if the log file is not found
         * @throws ParseException
         *             thrown the date format is invalid
         * @throws URISyntaxException
         *             thrown if the URI is invalid
         */
        public void parseFile(String filename) throws IOException,
                        FileNotFoundException, ParseException, URISyntaxException {
                String[] lines = FileTools.getLinesFromFile(filename);

                Map<String, List<Integer>> cookieSessionMap = new HashMap<String, List<Integer>>();
                int lastId = -1;

                SimpleDateFormat dateFormat = new SimpleDateFormat(
                                "yyyy-MM-dd HH:mm:ss");
                loadRobotRegex();

                sequences = new ArrayList<List<WebEvent>>();

                for (String line : lines) {
                        String[] values = line.substring(1, line.length() - 1).split(
                                        "\" \"");

                        // use cookie as session identifier
                        int cookieStart = values[0].lastIndexOf('.');
                        String cookie = values[0].substring(cookieStart + 1);
                        String dateString = values[1];
                        long timestamp = dateFormat.parse(dateString).getTime();
                        String uriString = values[2];
                        // String ref = values[3]; // referer is not yet used!
                        String agent;
                        if (values.length > 4) {
                                agent = values[4];
                        } else {
                                agent = "noagent";
                        }

                        List<String> postedVars = new ArrayList<String>();
                        if (values.length == 6) { // post vars found
                                for (String postVar : values[5].trim().split(" ")) {
                                        postedVars.add(postVar);
                                }
                        }
                        if (!isRobot(agent)) {
                                URI uri = new URI(uriString);

                                String path = uri.getPath();
                                List<String> getVars = extractGetVarsFromUri(uri);

                                WebEvent event = new WebEvent(path, timestamp, postedVars,
                                                getVars);

                                // find session and add event
                                List<Integer> sessionIds = cookieSessionMap.get(cookie);
                                if (sessionIds == null) {
                                        sessionIds = new ArrayList<Integer>();
                                        // start new session
                                        sessionIds.add(++lastId);
                                        cookieSessionMap.put(cookie, sessionIds);
                                        sequences.add(new LinkedList<WebEvent>());
                                }
                                Integer lastSessionIndex = sessionIds
                                                .get(sessionIds.size() - 1);
                                List<WebEvent> lastSession = sequences.get(lastSessionIndex);
                                long lastEventTime = timestamp;
                                if (!lastSession.isEmpty()) {
                                        lastEventTime = lastSession.get(lastSession.size() - 1)
                                                        .getTimestamp();
                                }
                                if (timestamp - lastEventTime > timeout) {
                                        sessionIds.add(++lastId);
                                        List<WebEvent> newSession = new LinkedList<WebEvent>();
                                        newSession.add(event);
                                        sequences.add(newSession);
                                } else {
                                        lastSession.add(event);
                                }
                        }
                }
                pruneShortSequences();
        }

        /**
         * <p>
         * Prunes sequences shorter than {@link #minLength}.
         * </p>
         */
        private void pruneShortSequences() {
                Console.traceln("" + sequences.size() + " user sequences found");
                // prune sequences shorter than min-length
                int i = 0;
                while (i < sequences.size()) {
                        if (sequences.get(i).size() < minLength) {
                                sequences.remove(i);
                        } else {
                                i++;
                        }
                }
                Console.traceln("" + sequences.size()
                                + " remaining after pruning of sequences shorter than "
                                + minLength);
        }

        /**
         * <p>
         * Reads {@link #ROBOTFILTERFILE} and creates a regular expression that
         * matches all the robots defined in the file. The regular expression is
         * stored in the field {@link #robotRegex}.
         * </p>
         * 
         * @throws IOException
         *             thrown if there is a problem reading the robot filter
         * @throws FileNotFoundException
         *             thrown if the robot filter is not found
         */
        private void loadRobotRegex() throws IOException, FileNotFoundException {
                String[] lines = FileTools.getLinesFromFile(ROBOTFILTERFILE);
                StringBuilder regex = new StringBuilder();
                for (int i = 0; i < lines.length; i++) {
                        regex.append("(.*" + lines[i] + ".*)");
                        if (i != lines.length - 1) {
                                regex.append('|');
                        }
                }
                robotRegex = regex.toString();
        }

        /**
         * <p>
         * Checks whether an agent is a robot.
         * </p>
         * 
         * @param agent
         *            agent that is checked
         * @return true, if the agent is a robot; false otherwise
         */
        private boolean isRobot(String agent) {
                return agent.matches(robotRegex);
        }

        /**
         * <p>
         * Parses the URI and extracts the GET variables that have been passed.
         * </p>
         * 
         * @param uri
         *            URI that is parsed
         * @return a list with all GET variables
         */
        private List<String> extractGetVarsFromUri(URI uri) {
                List<String> getVars = new ArrayList<String>();
                String query = uri.getQuery();
                if (query != null) {
                        String[] paramPairs = query.split("&");
                        for (String paramPair : paramPairs) {
                                String[] paramSplit = paramPair.split("=");
                                getVars.add(paramSplit[0]);
                        }
                }
                return getVars;
        }
}