SDIS1819-T2G01

import java.rmi.registry.Registry;

import java.rmi.registry.LocateRegistry;

import java.rmi.RemoteException;

import java.rmi.server.UnicastRemoteObject;

import java.util.Map;

import java.util.concurrent.ConcurrentHashMap;

import java.util.concurrent.ScheduledThreadPoolExecutor;

import java.util.concurrent.TimeUnit;

import java.util.concurrent.atomic.AtomicBoolean;

import java.util.concurrent.Executors;

import java.util.concurrent.CopyOnWriteArrayList;;

import java.util.ArrayList;

import java.util.List;

import java.util.Comparator;

import java.util.HashSet;

import java.util.Collections;

import java.io.*;

import java.net.DatagramPacket;

import java.nio.file.*;

//Server class essentially a Peer

public class Server implements PeerInterface {

    // Unique peer id

    public String id;

    // Size controls

    public static final int DEFAULT_MAX_SIZE = 1000000000;

    public int limit;

    public int used;

    // Thread Pool

    public static ScheduledThreadPoolExecutor pool;

    // Sockets

    public static Socket MC;

    public static Socket MDB;

    public static Socket MDR;

    // State Backup

    public boolean doingBackUp;

    public String file;

    public int replications;

    // State Restore

    public boolean restoring;

    public AtomicBoolean waitRestoreReply = new AtomicBoolean(false);

    public ConcurrentHashMap<String, Chunk> recoveredChunks = new ConcurrentHashMap<String, Chunk>(); // ChunkNo ->

                                                                                                      // Chunk

    // Service Management Information

    public ConcurrentHashMap<String, Chunk> chunks = new ConcurrentHashMap<String, Chunk>(); // fileId-ChunkNo

                                                                                             // -> Chunk

    public ConcurrentHashMap<String, String> files = new ConcurrentHashMap<String, String>(); // fileId -> // file name

    // Empty Constructor

    public Server() {

    }

    // Simplified Constructor(Default values)

    public Server(String id) throws IOException {

        this.used = 0;

        this.id = id;

        this.limit = DEFAULT_MAX_SIZE;

        this.setupSockets();

        this.loadLocal();

        this.setupDirectory();

    }

    // Full constructor

    public Server(String id, int portMC, String addressMC, int portMDB, String addressMDB, int portMDR,

            String addressMDR) throws IOException {

        this.used = 0;

        this.id = id;

        this.limit = DEFAULT_MAX_SIZE;

        this.setupSockets(portMC, addressMC, portMDB, addressMDB, portMDR, addressMDR);

        this.loadLocal();

        this.setupDirectory();

    }

    // Backup Protocol

    public void backup(String path, int replications) throws RemoteException {

        // Start backup

        this.doingBackUp = true;

        // Extract file name

        int index = path.lastIndexOf("\\");

        String fileName = path.substring(index + 1);

        // Generate Hash from file name and date

        String fileId = FileManager.hash(fileName + Long.toString(new File(path).lastModified()));

        // Is file backed up already?

        if (this.files.get(fileId) != null) {

            System.out.println("File already backed up");

            return;

        }

        // Add to file list

        this.files.put(fileId, fileName);

        try {

            // Get file bytes

            byte[] bytes = FileManager.readFile(path);

            // Get file in chunks

            byte[][] chunks = FileManager.split(bytes);

            // Send each chunk

            for (int i = 0; i < chunks.length; i++) {

                // Base receive time of 1 second

                int receiveTime = 1000;

                // PUTCHUNK tries

                for (int j = 0; j < 5; j++) {

                    // Prepare message

                    Message msg = new Message(Message.MessageType.PUTCHUNK, id, fileId, i, replications, chunks[i]);

                    // Pack in datagram

                    DatagramPacket packet = msg.packit(MDB.address, MDB.port);

                    // Send message

                    MDB.socket.send(packet);

                    // Wait for replies and check Replication level

                    this.replications = 0;

                    this.file = fileId;

                    Thread.sleep(receiveTime);

                    if (this.replications >= replications) {

                        break;

                    }

                    // Double receive time

                    receiveTime *= 2;

                }

            }

        } catch (Exception e) {

            e.printStackTrace();

        }

        // Terminate backup

        this.doingBackUp = false;

    }

    // Restore Protocol

    public void restore(String path) throws RemoteException {

        this.restoring = true;

        // File name

        int index = path.lastIndexOf("\\");

        String fileName = path.substring(index + 1);

        // Generate Hash from file name and date

        String fileId = FileManager.hash(fileName + Long.toString(new File(path).lastModified()));

        // Find in list of backed up

        String name = this.files.get(fileId);

        // File not backed up yet, just return

        if (name == null) {

            System.out.println("File not backed up by this peer");

            return;

        }

        try {

            // Get byte count (probably better than actually fetching the bytes array)

            File file = new File(path);

            int bytes = (int) file.length();

            // How many chunks to expect

            int chunks = 1 + bytes / FileManager.chunkSize;

            // Reset list of Chunks recovered

            this.recoveredChunks.clear();

            // Request chunks

            for (int i = 0; i < chunks; i++) {

                // Prepare message

                Message msg = new Message(Message.MessageType.GETCHUNK, id, fileId, i, 0, new byte[0]);

                // Pack in datagram

                DatagramPacket packet = msg.packit(MC.address, MC.port);

                // Send message

                MC.socket.send(packet);

                // Wait for response

                this.waitRestoreReply.set(true);

                long time = System.nanoTime();

                while (this.waitRestoreReply.get()) {

                    // Restore timeout

                    if (TimeUnit.NANOSECONDS.toMillis(time) - TimeUnit.NANOSECONDS.toMillis(System.nanoTime()) > 1000) {

                        System.out.println("Restore timeout, missing chunks");

                        return;

                    }

                }

            }

            // Get simple list from recovered chunks

            List<Chunk> list = new ArrayList<Chunk>(this.recoveredChunks.values());

            // Sort chunks

            Collections.sort(list, new Comparator<Chunk>() {

                @Override

                public int compare(Chunk p1, Chunk p2) {

                    return p1.chunkN - p2.chunkN; // Ascending

                }

            });

            // Pack chunks

            byte[][] allBytes = new byte[list.size()][];

            for (int i = 0; i < list.size(); i++) {

                allBytes[i] = list.get(i).bytes;

            }

            // Merge chunks

            byte[] fileBytes = FileManager.merge(allBytes);

            // Save file

            Path current = Paths.get("");

            String place = current.toAbsolutePath().toString() + "\\peer" + id + "\\restored\\" + fileName;

            try (FileOutputStream stream = new FileOutputStream(place)) {

                stream.write(fileBytes);

                stream.close();

            }

        } catch (Exception e) {

            e.printStackTrace();

        }

        this.restoring = false;

    }

    // Delete chunks associated to this file

    public void delete(String path) throws RemoteException {

        // File name

        int index = path.lastIndexOf("\\");

        String fileName = path.substring(index + 1);

        // Generate Hash from file name and date

        String fileId = FileManager.hash(fileName + Long.toString(new File(path).lastModified()));

        // Remove from list of backed up

        String name = this.files.get(fileId);

        if (name != null) {

            this.files.remove(fileId);

        }

        try {

            // Prepare message

            Message msg = new Message(Message.MessageType.DELETE, id, fileId, 0, 0, new byte[0]);

            // Pack in datagram

            DatagramPacket packet = msg.packit(MC.address, MC.port);

            // Send message

            MC.socket.send(packet);

        } catch (Exception e) {

            e.printStackTrace();

        }

    }

    public void reclaim(int memory) throws RemoteException {

        // Memory can't be lower than 0

        if (memory < 0) {

            return;

        }

        // Assign new limit

        limit = memory;

        try {

            // Check need to delete chunks

            // Going to delete by order in the map

            while (used > limit) {

                // Pick an entry

                Map.Entry<String, Chunk> entry = chunks.entrySet().iterator().next();

                // Remove from used space

                used -= entry.getValue().bytes.length;

                // Prepare message

                Message msg = new Message(Message.MessageType.REMOVED, id, entry.getValue().fileId,

                        entry.getValue().chunkN, 0, new byte[0]);

                // Pack in datagram

                DatagramPacket packet = msg.packit(MC.address, MC.port);

                // Send message

                MC.socket.send(packet);

                // Remove from map

                chunks.remove(entry.getKey());

                // Remove from file system

                Path current = Paths.get("");

                String place = current.toAbsolutePath().toString() + "\\peer" + id + "\\backup\\"

                        + entry.getValue().fileId + "\\chk" + entry.getValue().chunkN + ".chk";

                File toDelete = new File(place);

                toDelete.delete();

            }

        } catch (Exception e) {

            e.printStackTrace();

        }

    }

    public void state() throws RemoteException {

    }

    // Get information of previous peer life from file system

    public void loadLocal() {

        // Base path

        Path currentRelativePath = Paths.get("");

        String peerDir = currentRelativePath.toAbsolutePath().toString() + "\\peer" + id;

        // Backup path

        File file = new File(peerDir + "\\backup");

        // FileIds backed up

        File[] files = file.listFiles(File::isDirectory);

        // Peer didn't exist, just return

        if (files == null)

            return;

        // Each file directory

        for (int i = 0; i < files.length; i++) {

            // FileId

            String fileId = files[i].getName();

            // Get Chunks inside

            file = new File(peerDir + "\\backup" + "\\" + fileId);

            File[] chunks = file.listFiles();

            // No chunks, just return

            if (chunks == null)

                return;

            // Each chunk

            for (int j = 0; j < chunks.length; j++) {

                // Chunk name

                String chunkNo = chunks[j].getName();

                // Remove chk

                chunkNo = chunkNo.replaceAll("\\.", "");

                chunkNo = chunkNo.replaceAll("chk", "");

                try {

                    // Read bytes

                    byte[] bytes = Files.readAllBytes(chunks[j].toPath());

                    // Updated used bytes

                    used += bytes.length;

                    // Add to HashMap

                    this.chunks.put(fileId + "-" + chunkNo, new Chunk(fileId, Integer.parseInt(chunkNo), bytes, 0));

                } catch (Exception e) {

                    e.printStackTrace();

                }

            }

        }

    }

    // Setup directory

    public void setupDirectory() {

        // Base path

        Path currentRelativePath = Paths.get("");

        String peerDir = currentRelativePath.toAbsolutePath().toString() + "\\peer" + id;

        // Backup path

        File file = new File(peerDir + "\\backup");

        file.mkdirs();

        // Backup path

        file = new File(peerDir + "\\restored");

        file.mkdirs();

    }

    // Default Socket Setup

    public void setupSockets() throws IOException {

        pool = (ScheduledThreadPoolExecutor) Executors.newScheduledThreadPool(10000);

        MC = new Socket(this, Socket.Type.MC);

        pool.execute(MC);

        MDB = new Socket(this, Socket.Type.MDB);

        pool.execute(MDB);

        MDR = new Socket(this, Socket.Type.MDR);

        pool.execute(MDR);

    }

    // Specifc Socket Setup

    public void setupSockets(int portMC, String addressMC, int portMDB, String addressMDB, int portMDR,

            String addressMDR) throws IOException {

        pool = (ScheduledThreadPoolExecutor) Executors.newScheduledThreadPool(10000);

        MC = new Socket(this, Socket.Type.MC, portMC, addressMC);

        pool.execute(MC);

        MDB = new Socket(this, Socket.Type.MDB, portMDB, addressMDB);

        pool.execute(MDB);

        MDR = new Socket(this, Socket.Type.MDR, portMDR, addressMDR);

        pool.execute(MDR);

    }

    public static void main(String args[]) {

        try {

            // Server object

            Server obj;

            // Basic (version id)

            if (args.length == 2) {

                obj = new Server(args[1]);

            }

            // Full (version id access port mc port mdb port mdr)

            else if (args.length == 9) {

                obj = new Server(args[1], Integer.parseInt(args[3]), args[4], Integer.parseInt(args[5]), args[6],

                        Integer.parseInt(args[7]), args[8]);

            }

            // Invalid arguments

            else {

                System.out.println("java Server <version> <server id>");

                System.out.println(

                        "java Server <version> <server id> <access_point> <MC_port> <MC_IP_address> <MDB_port> <MDB_IP_address> <MDR_port> <MDR_IP_address>");

                return;

            }

            // Bind the server as a registry

            PeerInterface stub = (PeerInterface) UnicastRemoteObject.exportObject(obj, 0);

            // Bind the remote object's stub in the registry

            Registry registry = LocateRegistry.getRegistry();

            registry.bind(obj.id, stub);

            System.err.println("Server ready");

        } catch (Exception e) {

            System.err.println("Server exception: " + e.toString());

            e.printStackTrace();

        }

    }

}

import java.util.Random;

import java.rmi.registry.Registry;

import java.rmi.registry.LocateRegistry;

import java.rmi.RemoteException;

import java.rmi.server.UnicastRemoteObject;

import java.util.Map;

import java.util.concurrent.ConcurrentHashMap;

import java.util.concurrent.ScheduledThreadPoolExecutor;

import java.util.concurrent.TimeUnit;

import java.util.concurrent.atomic.AtomicBoolean;

import java.util.concurrent.Executors;

import java.util.concurrent.CopyOnWriteArrayList;

import java.util.ArrayList;

import java.util.List;

import java.util.Comparator;

import java.util.HashSet;

import java.util.Collections;

import java.io.*;

import java.net.DatagramPacket;

import java.nio.file.*;

public class Interpreter implements Runnable {

    public Random rand = new Random();

    private static final byte CR = 0xD;

    private static final byte LF = 0xA;

    public Server peer;

    public String raw;

    public String header;

    public byte[] body;

    public String version;

    public String senderId;

    public String fileId;

    public String chunkNo;

    public String replication;

    public AtomicBoolean elseSentChunk = new AtomicBoolean(false);

    public AtomicBoolean elseSentChunkReclaim = new AtomicBoolean(true);

    public Message.MessageType type;

    public Interpreter() {

    }

    public Interpreter(Server peer, DatagramPacket packet) {

        // Set peer

        this.peer = peer;

        // Seperate header and body

        messageSplitHeaderBody(packet.getData(), packet.getLength());

        System.out.println(header);

        // Get parts

        String[] parts = header.split(" ");

        // Identify type and specific arguments

        switch (parts[0]) {

        case "PUTCHUNK":

            type = Message.MessageType.PUTCHUNK;

            chunkNo = parts[4];

            replication = parts[5];

            break;

        case "STORED":

            type = Message.MessageType.STORED;

            chunkNo = parts[4];

            break;

        case "GETCHUNK":

            type = Message.MessageType.GETCHUNK;

            chunkNo = parts[4];

            break;

        case "CHUNK":

            type = Message.MessageType.CHUNK;

            chunkNo = parts[4];

            break;

        case "DELETE":

            type = Message.MessageType.DELETE;

            break;

        case "REMOVED":

            type = Message.MessageType.REMOVED;

            chunkNo = parts[4];

            break;

        default:

            break;

        }

        // Version, SenderId and FileId are shared

        version = parts[1];

        senderId = parts[2];

        fileId = parts[3];

    }

    // Split message header and body

    public void messageSplitHeaderBody(byte[] message, int size) {

        // Find index of CRLF

        int i = 0;

        for (i = 0; i < size; i++) {

            if (i <= size - 5) {

                if (message[i] == CR && message[i + 1] == LF && message[i + 2] == CR && message[i + 3] == LF) {

                    break;

                }

            }

        }

        // Get header

        byte[] headerByte = new byte[i];

        System.arraycopy(message, 0, headerByte, 0, i);

        header = new String(headerByte);

        header = header.trim();

        // Get body

        if (size > i + 3) {

            body = new byte[size - i - 4];

            System.arraycopy(message, i + 4, body, 0, size - i - 4);

        } else {

            body = null;

        }

    }

    @Override

    public void run() {

        // Do whatever the message asks

        try {

            // Identify Type

            switch (type) {

            case PUTCHUNK:

                // Someone(NOT US!) sent a CHUNK, cancel it

                if (this.elseSentChunkReclaim.get() && senderId != this.peer.id)

                    this.elseSentChunkReclaim.set(true);

                // Dont backup self

                if (peer.doingBackUp)

                    return;

                // Check peer has enough size available

                if (peer.used + body.length > peer.limit)

                    return;

                // Get path to peer

                Path currentRelativePath = Paths.get("");

                String peerDir = currentRelativePath.toAbsolutePath().toString() + "\\peer" + peer.id;

                peerDir += "\\backup";

                peerDir += "\\" + fileId;

                File file = new File(peerDir);

                // Create path

                file.mkdirs();

                // Store chunk in file system

                peerDir += "\\chk" + chunkNo + ".chk";

                File chunk = new File(peerDir);

                FileOutputStream out = new FileOutputStream(chunk);

                out.write(body);

                out.close();

                // Store chunk in Peer cache(hashmap)

                peer.chunks.put(fileId + "-" + chunkNo,

                        new Chunk(fileId, Integer.parseInt(chunkNo), body, Integer.parseInt(replication)));

                // Add to used memory

                peer.used += body.length;

                // Random delay

                Thread.sleep(rand.nextInt(400));

                // Send STORED to MC

                Message msg = new Message(Message.MessageType.STORED, peer.id, fileId, Integer.parseInt(chunkNo), 0,

                        new byte[0]);

                DatagramPacket packet = msg.packit(Server.MC.address, Server.MC.port);

                Server.MC.socket.send(packet);

                break;

            case STORED:

                // If doing backup then add to replications

                if (peer.doingBackUp && peer.file.equals(fileId)) {

                    peer.replications++;

                }

                // Chunk that was stored

                String keyStored = fileId + "-" + chunkNo;

                // If we have the chunk

                if (this.peer.chunks.get(keyStored) != null) {

                    this.peer.chunks.get(keyStored).cReps++;

                }

                break;

            case GETCHUNK:

                // Find chunk in store

                Chunk requestedChunk = peer.chunks.get(fileId + "-" + chunkNo);

                // Chunk not found, just return

                if (requestedChunk == null)

                    return;

                // Set flag to lookout for CHUNK

                this.elseSentChunk.set(false);

                // Wait random delay

                Thread.sleep(rand.nextInt(400));

                // Someone else sent the CHUNK, just return

                if (this.elseSentChunk.get())

                    return;

                // Send CHUNK to MDR

                Message msgGetChunk = new Message(Message.MessageType.CHUNK, peer.id, fileId, Integer.parseInt(chunkNo),

                        0, requestedChunk.bytes);

                DatagramPacket packetGetChunk = msgGetChunk.packit(Server.MDR.address, Server.MDR.port);

                Server.MDR.socket.send(packetGetChunk);

                break;

            case CHUNK:

                // Find chunk in store

                Chunk receivedChunk = peer.chunks.get(fileId + "-" + chunkNo);

                // Someone(NOT US!) sent a CHUNK we were going to send, cancel it

                if (receivedChunk != null && senderId != this.peer.id) {

                    this.elseSentChunk.set(true);

                }

                // Add to recovered if not there yet

                if (this.peer.restoring) {

                    if (!this.peer.recoveredChunks.containsKey(chunkNo)) {

                        this.peer.recoveredChunks.put(chunkNo, new Chunk(fileId, Integer.parseInt(chunkNo), body, 0));

                        // Chunk received, continue asking for rest

                        if (peer.waitRestoreReply.get())

                            peer.waitRestoreReply.set(false);

                    }

                }

                break;

            case DELETE:

                boolean found1 = false;

                // Delete cache chunks

                for (String keyDelete : this.peer.chunks.keySet()) {

                    if (keyDelete.contains(this.fileId)) {

                        found1 = true;

                        this.peer.chunks.remove(keyDelete);

                    }

                }

                // Delete filesystem chunks

                // If at least one in cache was found then surely it exists in file system and

                // we should delete

                if (found1) {

                    Path current = Paths.get("");

                    String fileDir = current.toAbsolutePath().toString() + "\\peer" + peer.id;

                    fileDir += "\\backup";

                    fileDir += "\\" + fileId;

                    File fileDirFile = new File(fileDir);

                    FileManager.deleteDir(fileDirFile);

                }

                break;

            case REMOVED:

                // Chunk requested

                String key = fileId + "-" + chunkNo;

                // If we have the chunk

                if (this.peer.chunks.get(key) != null) {

                    // Remove replication

                    this.peer.chunks.get(key).cReps--;

                    System.out.println(this.peer.chunks.get(key).cReps);

                    System.out.println(this.peer.chunks.get(key).reps);

                    // If bellow replication degree

                    if (this.peer.chunks.get(key).cReps < this.peer.chunks.get(key).reps) {

                        // Wait random delay

                        this.elseSentChunkReclaim.set(false);

                        Thread.sleep(rand.nextInt(400));

                        // Someone already started backup of this chunk

                        if (this.elseSentChunkReclaim.get())

                            return;

                        // Prepare message

                        Message msgRemovedChunk = new Message(Message.MessageType.PUTCHUNK, this.peer.id, fileId,

                                this.peer.chunks.get(key).chunkN, this.peer.chunks.get(key).reps,

                                this.peer.chunks.get(key).bytes);

                        // Pack in datagram

                        DatagramPacket packetRemovedChunk = msgRemovedChunk.packit(this.peer.MDB.address,

                                this.peer.MDB.port);

                        // Send message

                        this.peer.MDB.socket.send(packetRemovedChunk);

                    }

                }

                break;

            default:

                break;

            }

        } catch (Exception e) {

            e.printStackTrace();

        }

    }

}

import java.io.*;

import java.nio.file.*;

import java.security.*;

import java.nio.charset.*;

public class FileManager {

    public static int chunkSize = 64000;

    // Save byte array chunk to path

    public static void saveChunk(byte[] bytes, String path, int chunkN) throws FileNotFoundException, IOException {

        String fileName = path + Integer.toString(chunkN);

        try (FileOutputStream stream = new FileOutputStream(fileName)) {

            stream.write(bytes);

        }

    }

    // Hash a string with SHA256

    public static String hash(String input) {

        try {

            byte[] bytes = digestHashing(input);

            return bytesToHex(bytes);

        } catch (Exception e) {

            e.printStackTrace();

        }

        return null;

    }

    // Use MessageDigest to hash in bytes

    private static byte[] digestHashing(String input) throws NoSuchAlgorithmException {

        MessageDigest digest = MessageDigest.getInstance("SHA-256");

        return digest.digest(input.getBytes(StandardCharsets.UTF_8));

    }

    // Use bytes from MessageDigest to a String

    private static String bytesToHex(byte[] hash) {

        StringBuffer hexString = new StringBuffer();

        for (int i = 0; i < hash.length; i++) {

            String hex = Integer.toHexString(0xff & hash[i]);

            if (hex.length() == 1)

                hexString.append('0');

            hexString.append(hex);

        }

        return hexString.toString();

    }

    // Delete directory and files

    public static void deleteDir(File file) {

        File[] contents = file.listFiles();

        if (contents != null) {

            for (File f : contents) {

                if (!Files.isSymbolicLink(f.toPath())) {

                    deleteDir(f);

                }

            }

        }

        file.delete();

    }

    // Read all bytes of file(generic use)

    public static byte[] readFile(String path) {

        Path filePath = Paths.get(path);

        byte[] bytes = null;

        try {

            bytes = Files.readAllBytes(filePath);

        } catch (Exception e) {

            e.printStackTrace();

        }

        return bytes;

    }

    // Split file in chunks

    public static byte[][] split(byte[] fileBytes) {

        // Number of chunks needed is always integer division plus 1 which may be

        // partially used or empty

        int nChunks = 1 + fileBytes.length / chunkSize;

        // Total bytes

        int bytes = fileBytes.length;

        int rBytes = 0;

        // Chunks seperated

        byte[][] chunks = new byte[nChunks][];

        for (int i = 0; i < nChunks; i++) {

            // Calculate proper size

            int sizeToCopy = chunkSize;

            if (bytes < sizeToCopy)

                sizeToCopy = bytes;

            // Chunk with proper size

            chunks[i] = new byte[sizeToCopy];

            // Copy to chunk

            System.arraycopy(fileBytes, rBytes, chunks[i], 0, sizeToCopy);

            // Remove form total bytes

            bytes -= sizeToCopy;

            rBytes += sizeToCopy;

        }

        return chunks;

    }

    // Merge chunks into single byte array

    public static byte[] merge(byte[][] chunks) throws IOException {

        // Total bytes

        int tBytes = 0;

        for (int i = 0; i < chunks.length; i++) {

            tBytes += chunks[i].length;

        }

        byte[] mergedFile = new byte[tBytes];

        // Written bytes count

        int nBytes = 0;

        // Write bytes

        for (int i = 0; i < chunks.length; i++) {

            System.arraycopy(chunks[i], 0, mergedFile, nBytes, chunks[i].length);

            nBytes += chunks[i].length;

        }

        return mergedFile;

    }

    // Test main for split and merge file

    public static void main(String[] args) {

        String fileName = args[0];

        Path filePath = Paths.get(fileName);

        byte[] fileBytes = null;

        try {

            fileBytes = Files.readAllBytes(filePath);

        } catch (Exception e) {

            e.printStackTrace();

        }

        byte[][] chunks = split(fileBytes);

        try {

            fileBytes = merge(chunks);

        } catch (Exception e) {

            e.printStackTrace();

        }

    }

}

import java.rmi.registry.LocateRegistry;

import java.rmi.registry.Registry;

public class Client {

    public static void main(String[] args) {

        // Command parameters

        String[] opnd = { "operand", "opnd1", "opnd2" };

        // Process Arguments

        // 2 arguments can only be STATE check

        if (args.length == 2) {

            opnd[0] = "STATE";

        }

        // 3 arguments can only be RECLAIM/DELETE/RESTORE

        else if (args.length == 3) {

            switch (args[1]) {

            case "RESTORE":

                opnd[0] = "RESTORE";

                // File

                opnd[1] = args[2];

                break;

            case "DELETE":

                opnd[0] = "DELETE";

                // File

                opnd[1] = args[2];

                break;

            case "RECLAIM":

                opnd[0] = "RECLAIM";

                // Reclaim size

                opnd[1] = args[2];

                break;

            default:

                System.out.println("Error: Invalid operation name");

                return;

            }

        }

        // 4 arguments can only be BACKUP

        else if (args.length == 4) {

            opnd[0] = "BACKUP";

            // File

            opnd[1] = args[2];

            // Replication level

            opnd[2] = args[3];

        }

        // Any more arguments are invalid too

        else {

            System.out.println("java Client <peer_ap> <protocol> <opnd_1> <opnd_2");

            return;

        }

        // Host id

        String[] host = new String(args[0]).split("/");

        try {

            PeerInterface stub;

            // Lookup for RMI

            if(host.length > 2){

                Registry registry = LocateRegistry.getRegistry(host[2]);

                stub = (PeerInterface) registry.lookup(host[3]);

            }else{

                Registry registry = LocateRegistry.getRegistry();

                stub = (PeerInterface) registry.lookup(args[0]);

            }                     

            // Identify action

            switch (opnd[0]) {

            case "BACKUP":

                stub.backup(opnd[1], Integer.parseInt(opnd[2]));

                break;

            case "RESTORE":

                stub.restore(opnd[1]);

                break;

            case "DELETE":

                stub.delete(opnd[1]);

                break;

            case "RECLAIM":

                stub.reclaim(Integer.parseInt(opnd[1]));

                break;

            default:

                break;

            }

        } catch (Exception e) {

            System.err.println("Client exception: " + e.toString());

            e.printStackTrace();

        }

    }

}

public class Chunk {

    public String fileId;

    public int chunkN;

    public byte[] bytes;

    public int reps;

    public int cReps = 0;

    public Chunk(String fileId, int chunkN, byte[] bytes, int reps) {

        this.fileId = fileId;

        this.chunkN = chunkN;

        this.bytes = bytes;

        this.reps = reps;

    }

}

import java.io.IOException;

import java.net.DatagramPacket;

import java.net.InetAddress;

import java.net.MulticastSocket;

import java.util.AbstractMap.SimpleEntry;

public class Socket implements Runnable {

    public MulticastSocket socket;

    public int port;

    public InetAddress address;

    public enum Type {

        MC, MDB, MDR

    }

    public Type type;

    public Server peer;

    // Message size(safe size)

    public static final int MESSAGE_SIZE = 65500;

    // Default constructor

    public Socket(Server peer, Type type) throws IOException {

        this.peer = peer;

        switch (type) {

        case MC:

            this.port = 8000;

            this.address = InetAddress.getByName("224.0.0.1");

            break;

        case MDB:

            this.port = 8001;

            this.address = InetAddress.getByName("224.0.0.2");

            break;

        case MDR:

            this.port = 8002;

            this.address = InetAddress.getByName("224.0.0.3");

            break;

        default:

            return;

        }

        this.type = type;

        this.socket = new MulticastSocket(this.port);

        this.socket.joinGroup(address);

    }

    // Specific constructor

    public Socket(Server peer, Type type, int port, String address) throws IOException {

        this.peer = peer;

        this.type = type;

        this.port = port;

        this.address = InetAddress.getByName(address);

        this.socket = new MulticastSocket(this.port);

        this.socket.joinGroup(this.address);

    }

    @Override

    public void run() {

        while (true) {

            byte[] buf = new byte[MESSAGE_SIZE];

            DatagramPacket packet = new DatagramPacket(buf, buf.length);

            try {

                this.socket.receive(packet);

                System.out.println("Packet received, launching interpreter");

                Server.pool.execute(new Interpreter(peer, packet));

            } catch (IOException e) {

                e.printStackTrace();

            }

        }

    }

}

import java.rmi.Remote;

import java.rmi.RemoteException;

public interface PeerInterface extends Remote {

    void backup(String path, int replications) throws RemoteException;

    void restore(String path) throws RemoteException;

    void state() throws RemoteException;

    void reclaim(int memory) throws RemoteException;

    void delete(String path) throws RemoteException;

}

import java.net.DatagramPacket;

import java.net.InetAddress;

public class Message {

    private static final String CRLF = "\r\n";

    public String header;

    public byte[] body;

    public enum MessageType {

        PUTCHUNK, STORED, GETCHUNK, CHUNK, DELETE, REMOVED

    };

    public MessageType type;

    public Message() {

    }

    // Build a message

    public Message(MessageType type, String senderId, String fileId, int chunkN, int replicationDeg, byte[] bytes) {

        // Reset body

        body = new byte[0];

        // Add chunk

        body = bytes;

        // Assign type

        this.type = type;

        // Prepare type

        switch (type) {

        case PUTCHUNK:

            header = "PUTCHUNK";

            break;

        case STORED:

            header = "STORED";

            break;

        case GETCHUNK:

            header = "GETCHUNK";

            break;

        case CHUNK:

            header = "CHUNK";

            break;

        case DELETE:

            header = "DELETE";

            break;

        case REMOVED:

            header = "REMOVED";

            break;

        default:

            break;

        }

        // Version, SenderId and FileId are shared

        // TODO hardcoded version 1.0

        header += " 1.0";

        header += " " + senderId;

        header += " " + fileId;

        // Remaining message header

        // Technically it would be more efficient to add chunkN to all types and remove

        // in DELETE but eh

        switch (type) {

        case PUTCHUNK:

            header += " " + Integer.toString(chunkN);

            header += " " + Integer.toString(replicationDeg);

            break;

        case STORED:

            header += " " + Integer.toString(chunkN);

            break;

        case GETCHUNK:

            header += " " + Integer.toString(chunkN);

            break;

        case CHUNK:

            header += " " + Integer.toString(chunkN);

            break;

        case DELETE:

            // Nothing to add

            break;

        case REMOVED:

            header += " " + Integer.toString(chunkN);

            break;

        default:

            break;

        }

        // Finalize with double CRLF

        header += CRLF + CRLF;

    }

    // Pack a datagram from message

    public DatagramPacket packit(InetAddress address, int port) {

        byte[] headerBytes = header.getBytes();

        byte[] full = new byte[headerBytes.length + body.length];

        System.arraycopy(headerBytes, 0, full, 0, headerBytes.length);

        System.arraycopy(body, 0, full, headerBytes.length, body.length);

        DatagramPacket packet = new DatagramPacket(full, full.length, address, port);

        return packet;

    }

}