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  • Displaying emails in a JTable (Java Swing)

    - by Paul
    Hi I'm new to all this. I have been trying to display fetched emails in a JTable using the JavaMail add-on. However when I ask the program to set the value it never does. I have been working in NetBeans if that is any help? the fetchMail class finds all may on a server. The gui class is used to display all emails in a table as well as creating mail. You will probably think that I have tried it like a bull in a china shop, I am new to Java and trying to give myself a challenge. Any help/advice would be greatly appreciated fetchMail: package mail; import java.util.; import java.io.; import java.text.DateFormat; import java.text.SimpleDateFormat; import javax.mail.; import javax.mail.internet.; import javax.mail.search.; import javax.activation.; public class fetchMail { public void fetch(String username, String pass, String search){ MessagesTableModel tableModel = new MessagesTableModel(); String complete; DateFormat df = new SimpleDateFormat("dd/MM/yyyy"); gui gui = new gui(); // SUBSTITUTE YOUR ISP's POP3 SERVER HERE!!! String host = "imap.gmail.com"; // SUBSTITUTE YOUR USERNAME AND PASSWORD TO ACCESS E-MAIL HERE!!! String user = username; String password = pass; // SUBSTITUTE YOUR SUBJECT SUBSTRING TO SEARCH HERE!!! String subjectSubstringToSearch = search; // Get a session. Use a blank Properties object. Session session = Session.getInstance(new Properties()); Properties props = System.getProperties(); props.setProperty("mail.store.protocol", "imaps"); props.setProperty("mail.imap.socketFactory.class", "javax.net.ssl.SSLSocketFactory"); props.setProperty("mail.imap.socketFactory.fallback", "false"); try { // Get a Store object Store store = session.getStore("imaps"); store.connect(host, user, password); // Get "INBOX" Folder fldr = store.getFolder("INBOX"); fldr.open(Folder.READ_WRITE); int count = fldr.getMessageCount(); System.out.println(count + " total messages"); // Message numebers start at 1 for(int i = 1; i <= count; i++) { // Get a message by its sequence number Message m = fldr.getMessage(i); // Get some headers Date date = m.getSentDate(); int pos = i - 1; String d = df.format(date); Address [] from = m.getFrom(); String subj = m.getSubject(); String mimeType = m.getContentType(); complete = date + "\t" + from[0] + "\t" + subj + "\t" + mimeType; //tableModel.setMessages(m); gui.setDate(d, pos); // System.out.println(d + " " + i); } // Search for e-mails by some subject substring String pattern = subjectSubstringToSearch; SubjectTerm st = new SubjectTerm(pattern); // Get some message references Message [] found = fldr.search(st); System.out.println(found.length + " messages matched Subject pattern \"" + pattern + "\""); for (int i = 0; i < found.length; i++) { Message m = found[i]; // Get some headers Date date = m.getSentDate(); Address [] from = m.getFrom(); String subj = m.getSubject(); String mimeType = m.getContentType(); //System.out.println(date + "\t" + from[0] + "\t" + // subj + "\t" + mimeType); Object o = m.getContent(); if (o instanceof String) { // System.out.println("**This is a String Message**"); // System.out.println((String)o); } else if (o instanceof Multipart) { // System.out.print("**This is a Multipart Message. "); Multipart mp = (Multipart)o; int count3 = mp.getCount(); // System.out.println("It has " + count3 + // " BodyParts in it**"); for (int j = 0; j < count3; j++) { // Part are numbered starting at 0 BodyPart b = mp.getBodyPart(j); String mimeType2 = b.getContentType(); // System.out.println( "BodyPart " + (j + 1) + // " is of MimeType " + mimeType); Object o2 = b.getContent(); if (o2 instanceof String) { // System.out.println("**This is a String BodyPart**"); // System.out.println((String)o2); } else if (o2 instanceof Multipart) { // System.out.print( // "**This BodyPart is a nested Multipart. "); Multipart mp2 = (Multipart)o2; int count2 = mp2.getCount(); // System.out.println("It has " + count2 + // "further BodyParts in it**"); } else if (o2 instanceof InputStream) { // System.out.println( // "**This is an InputStream BodyPart**"); } } //End of for } else if (o instanceof InputStream) { // System.out.println("**This is an InputStream message**"); InputStream is = (InputStream)o; // Assumes character content (not binary images) int c; while ((c = is.read()) != -1) { // System.out.write(c); } } // Uncomment to set "delete" flag on the message //m.setFlag(Flags.Flag.DELETED,true); } //End of for // "true" actually deletes flagged messages from folder fldr.close(true); store.close(); } catch (MessagingException mex) { // Prints all nested (chained) exceptions as well mex.printStackTrace(); } catch (IOException ioex) { ioex.printStackTrace(); } } } gui: /* * gui.java * * Created on 13-May-2010, 18:29:30 */ package mail; import java.text.DateFormat; import java.text.FieldPosition; import java.text.ParsePosition; import java.text.SimpleDateFormat; import java.util.Date; import java.util.Vector; import javax.mail.Address; import javax.swing.JScrollPane; import javax.swing.JTable; import javax.swing.ListSelectionModel; import javax.swing.event.ListSelectionEvent; import javax.swing.event.ListSelectionListener; import javax.swing.event.TableModelListener; import javax.swing.table.DefaultTableModel; import javax.swing.table.TableModel; public class gui extends javax.swing.JFrame { private MessagesTableModel tableModel; // Table listing messages. private JTable table; String date; /** Creates new form gui */ public gui() { initComponents(); } @SuppressWarnings("unchecked") private void initComponents() { recieve = new javax.swing.JButton(); jButton1 = new javax.swing.JButton(); jScrollPane1 = new javax.swing.JScrollPane(); inboxTable = new javax.swing.JTable(); setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE); recieve.setText("Receve"); recieve.addActionListener(new java.awt.event.ActionListener() { public void actionPerformed(java.awt.event.ActionEvent evt) { recieveActionPerformed(evt); } }); jButton1.setText("new"); jButton1.addActionListener(new java.awt.event.ActionListener() { public void actionPerformed(java.awt.event.ActionEvent evt) { jButton1ActionPerformed(evt); } }); inboxTable.setModel(new javax.swing.table.DefaultTableModel( new Object [][] { {null, null, null}, {null, null, null}, {null, null, null}, {null, null, null} }, new String [] { "Date", "subject", "sender" } ) { Class[] types = new Class [] { java.lang.String.class, java.lang.String.class, java.lang.String.class }; public Class getColumnClass(int columnIndex) { return types [columnIndex]; } }); jScrollPane1.setViewportView(inboxTable); inboxTable.getColumnModel().getColumn(0).setResizable(false); inboxTable.getColumnModel().getColumn(1).setResizable(false); inboxTable.getColumnModel().getColumn(2).setResizable(false); javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane()); getContentPane().setLayout(layout); layout.setHorizontalGroup( layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGroup(layout.createSequentialGroup() .addGap(39, 39, 39) .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 558, javax.swing.GroupLayout.PREFERRED_SIZE) .addGroup(layout.createSequentialGroup() .addComponent(recieve) .addGap(18, 18, 18) .addComponent(jButton1, javax.swing.GroupLayout.PREFERRED_SIZE, 75, javax.swing.GroupLayout.PREFERRED_SIZE))) .addGap(73, 73, 73)) ); layout.setVerticalGroup( layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGroup(layout.createSequentialGroup() .addGap(31, 31, 31) .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE) .addComponent(recieve) .addComponent(jButton1)) .addGap(18, 18, 18) .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 258, javax.swing.GroupLayout.PREFERRED_SIZE) .addContainerGap(179, Short.MAX_VALUE)) ); pack(); }// </editor-fold> private void recieveActionPerformed(java.awt.event.ActionEvent evt) { fetchMail fetch = new fetchMail(); fetch.fetch(email goes here, password goes here, search goes here); } private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) { createMail create = new createMail(); centerW center = new centerW(); //create.attVis(); center.center(create); create.setVisible(true); } public void setDate(String Date, int pos){ //pos = pos + 1; String [] s = new String [5]; s[pos] = Date; inboxTable.setValueAt(Date, pos, 0); } public String getDate(){ return date; } /** * @param args the command line arguments */ public static void main(String args[]) { java.awt.EventQueue.invokeLater(new Runnable() { public void run() { new gui().setVisible(true); } }); } // Variables declaration - do not modify private javax.swing.JTable inboxTable; private javax.swing.JButton jButton1; private javax.swing.JScrollPane jScrollPane1; private javax.swing.JButton recieve; // End of variables declaration }

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  • c++ queue template

    - by Dalton Conley
    ALright, pardon my messy code please. Below is my queue class. #include <iostream> using namespace std; #ifndef QUEUE #define QUEUE /*---------------------------------------------------------------------------- Student Class # Methods # Student() // default constructor Student(string, int) // constructor display() // out puts a student # Data Members # Name // string name Id // int id ----------------------------------------------------------------------------*/ class Student { public: Student() { } Student(string iname, int iid) { name = iname; id = iid; } void display(ostream &out) const { out << "Student Name: " << name << "\tStudent Id: " << id << "\tAddress: " << this << endl; } private: string name; int id; }; // define a typedef of a pointer to a student. typedef Student * StudentPointer; template <typename T> class Queue { public: /*------------------------------------------------------------------------ Queue Default Constructor Preconditions: none Postconditions: assigns default values for front and back to 0 description: constructs a default empty Queue. ------------------------------------------------------------------------*/ Queue() : myFront(0), myBack(0) {} /*------------------------------------------------------------------------ Copy Constructor Preconditions: requres a reference to a value for which you are copying Postconditions: assigns a copy to the parent Queue. description: Copys a queue and assigns it to the parent Queue. ------------------------------------------------------------------------*/ Queue(const T & q) { myFront = myBack = 0; if(!q.empty()) { // copy the first node myFront = myBack = new Node(q.front()); NodePointer qPtr = q.myFront->next; while(qPtr != NULL) { myBack->next = new Node(qPtr->data); myBack = myBack->next; qPtr = qPtr->next; } } } /*------------------------------------------------------------------------ Destructor Preconditions: none Postconditions: deallocates the dynamic memory for the Queue description: deletes the memory stored for a Queue. ------------------------------------------------------------------------*/ ~Queue() { NodePointer prev = myFront, ptr; while(prev != NULL) { ptr = prev->next; delete prev; prev = ptr; } } /*------------------------------------------------------------------------ Empty() Preconditions: none Postconditions: returns a boolean value. description: returns true/false based on if the queue is empty or full. ------------------------------------------------------------------------*/ bool empty() const { return (myFront == NULL); } /*------------------------------------------------------------------------ Enqueue Preconditions: requires a constant reference Postconditions: allocates memory and appends a value at the end of a queue description: ------------------------------------------------------------------------*/ void enqueue(const T & value) { NodePointer newNodePtr = new Node(value); if(empty()) { myFront = myBack = newNodePtr; newNodePtr->next = NULL; } else { myBack->next = newNodePtr; myBack = newNodePtr; newNodePtr->next = NULL; } } /*------------------------------------------------------------------------ Display Preconditions: requires a reference of type ostream Postconditions: returns the ostream value (for chaining) description: outputs the contents of a queue. ------------------------------------------------------------------------*/ void display(ostream & out) const { NodePointer ptr; ptr = myFront; while(ptr != NULL) { out << ptr->data << " "; ptr = ptr->next; } out << endl; } /*------------------------------------------------------------------------ Front Preconditions: none Postconditions: returns a value of type T description: returns the first value in the parent Queue. ------------------------------------------------------------------------*/ T front() const { if ( !empty() ) return (myFront->data); else { cerr << "*** Queue is empty -- returning garbage value ***\n"; T * temp = new(T); T garbage = * temp; delete temp; return garbage; } } /*------------------------------------------------------------------------ Dequeue Preconditions: none Postconditions: removes the first value in a queue ------------------------------------------------------------------------*/ void dequeue() { if ( !empty() ) { NodePointer ptr = myFront; myFront = myFront->next; delete ptr; if(myFront == NULL) myBack = NULL; } else { cerr << "*** Queue is empty -- " "can't remove a value ***\n"; exit(1); } } /*------------------------------------------------------------------------ pverloaded = operator Preconditions: requires a constant reference Postconditions: returns a const type T description: this allows assigning of queues to queues ------------------------------------------------------------------------*/ Queue<T> & operator=(const T &q) { // make sure we arent reassigning ourself // e.g. thisQueue = thisQueue. if(this != &q) { this->~Queue(); if(q.empty()) { myFront = myBack = NULL; } else { myFront = myBack = new Node(q.front()); NodePointer qPtr = q.myFront->next; while(qPtr != NULL) { myBack->next = new Node(qPtr->data); myBack = myBack->next; qPtr = qPtr->next; } } } return *this; } private: class Node { public: T data; Node * next; Node(T value, Node * first = 0) : data(value), next(first) {} }; typedef Node * NodePointer; NodePointer myFront, myBack, queueSize; }; /*------------------------------------------------------------------------ join Preconditions: requires 2 queue values Postconditions: appends queue2 to the end of queue1 description: this function joins 2 queues into 1. ------------------------------------------------------------------------*/ template <typename T> Queue<T> join(Queue<T> q1, Queue<T> q2) { Queue<T> q1Copy(q1), q2Copy(q2); Queue<T> jQueue; while(!q1Copy.empty()) { jQueue.enqueue(q1Copy.front()); q1Copy.dequeue(); } while(!q2Copy.empty()) { jQueue.enqueue(q2Copy.front()); q2Copy.dequeue(); } cout << jQueue << endl; return jQueue; } /*---------------------------------------------------------------------------- Overloaded << operator Preconditions: requires a constant reference and a Queue of type T Postconditions: returns the ostream (for chaining) description: this function is overloaded for outputing a queue with << ----------------------------------------------------------------------------*/ template <typename T> ostream & operator<<(ostream &out, Queue<T> &s) { s.display(out); return out; } /*---------------------------------------------------------------------------- Overloaded << operator Preconditions: requires a constant reference and a reference of type Student Postconditions: none description: this function is overloaded for outputing an object of type Student. ----------------------------------------------------------------------------*/ ostream & operator<<(ostream &out, Student &s) { s.display(out); } /*---------------------------------------------------------------------------- Overloaded << operator Preconditions: requires a constant reference and a reference of a pointer to a Student object. Postconditions: none description: this function is overloaded for outputing pointers to Students ----------------------------------------------------------------------------*/ ostream & operator<<(ostream &out, StudentPointer &s) { s->display(out); } #endif Now I'm having some issues with it. For one, when I add 0 to a queue and then I output the queue like so.. Queue<double> qdub; qdub.enqueue(0); cout << qdub << endl; That works, it will output 0. But for example, if I modify that queue in any way.. like.. assign it to a different queue.. Queue<double> qdub1; Queue<double> qdub2; qdub1.enqueue(0; qdub2 = qdub1; cout << qdub2 << endl; It will give me weird values for 0 like.. 7.86914e-316. Help on this would be much appreciated!

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  • Database Tutorial: The method open() is undefined for the type MainActivity.DBAdapter

    - by user2203633
    I am trying to do this database tutorial on SQLite Eclipse: https://www.youtube.com/watch?v=j-IV87qQ00M But I get a few errors at the end.. at db.ppen(); i get error: The method open() is undefined for the type MainActivity.DBAdapter and similar for insert record and close. MainActivity: package com.example.studentdatabase; import java.io.File; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import android.app.Activity; import android.app.ListActivity; import android.content.Intent; import android.database.Cursor; import android.os.Bundle; import android.util.Log; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.BaseAdapter; import android.widget.Button; import android.widget.Toast; public class MainActivity extends Activity { /** Called when the activity is first created. */ //DBAdapter db = new DBAdapter(this); @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); Button addBtn = (Button)findViewById(R.id.add); addBtn.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Intent i = new Intent(MainActivity.this, addassignment.class); startActivity(i); } }); try { String destPath = "/data/data/" + getPackageName() + "/databases/AssignmentDB"; File f = new File(destPath); if (!f.exists()) { CopyDB( getBaseContext().getAssets().open("mydb"), new FileOutputStream(destPath)); } } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } DBAdapter db = new DBAdapter(); //---add an assignment--- db.open(); long id = db.insertRecord("Hello World", "2/18/2012", "DPR 224", "First Android Project"); id = db.insertRecord("Workbook Exercises", "3/1/2012", "MAT 100", "Do odd numbers"); db.close(); //---get all Records--- /* db.open(); Cursor c = db.getAllRecords(); if (c.moveToFirst()) { do { DisplayRecord(c); } while (c.moveToNext()); } db.close(); */ /* //---get a Record--- db.open(); Cursor c = db.getRecord(2); if (c.moveToFirst()) DisplayRecord(c); else Toast.makeText(this, "No Assignments found", Toast.LENGTH_LONG).show(); db.close(); */ //---update Record--- /* db.open(); if (db.updateRecord(1, "Hello Android", "2/19/2012", "DPR 224", "First Android Project")) Toast.makeText(this, "Update successful.", Toast.LENGTH_LONG).show(); else Toast.makeText(this, "Update failed.", Toast.LENGTH_LONG).show(); db.close(); */ /* //---delete a Record--- db.open(); if (db.deleteRecord(1)) Toast.makeText(this, "Delete successful.", Toast.LENGTH_LONG).show(); else Toast.makeText(this, "Delete failed.", Toast.LENGTH_LONG).show(); db.close(); */ } private class DBAdapter extends BaseAdapter { private LayoutInflater mInflater; //private ArrayList<> @Override public int getCount() { return 0; } @Override public Object getItem(int arg0) { return null; } @Override public long getItemId(int arg0) { return 0; } @Override public View getView(int arg0, View arg1, ViewGroup arg2) { return null; } } public void CopyDB(InputStream inputStream, OutputStream outputStream) throws IOException { //---copy 1K bytes at a time--- byte[] buffer = new byte[1024]; int length; while ((length = inputStream.read(buffer)) > 0) { outputStream.write(buffer, 0, length); } inputStream.close(); outputStream.close(); } public void DisplayRecord(Cursor c) { Toast.makeText(this, "id: " + c.getString(0) + "\n" + "Title: " + c.getString(1) + "\n" + "Due Date: " + c.getString(2), Toast.LENGTH_SHORT).show(); } public void addAssignment(View view) { Intent i = new Intent("com.pinchtapzoom.addassignment"); startActivity(i); Log.d("TAG", "Clicked"); } } DBAdapter code: package com.example.studentdatabase; public class DBAdapter { public static final String KEY_ROWID = "id"; public static final String KEY_TITLE = "title"; public static final String KEY_DUEDATE = "duedate"; public static final String KEY_COURSE = "course"; public static final String KEY_NOTES = "notes"; private static final String TAG = "DBAdapter"; private static final String DATABASE_NAME = "AssignmentsDB"; private static final String DATABASE_TABLE = "assignments"; private static final int DATABASE_VERSION = 2; private static final String DATABASE_CREATE = "create table if not exists assignments (id integer primary key autoincrement, " + "title VARCHAR not null, duedate date, course VARCHAR, notes VARCHAR );"; private final Context context; private DatabaseHelper DBHelper; private SQLiteDatabase db; public DBAdapter(Context ctx) { this.context = ctx; DBHelper = new DatabaseHelper(context); } private static class DatabaseHelper extends SQLiteOpenHelper { DatabaseHelper(Context context) { super(context, DATABASE_NAME, null, DATABASE_VERSION); } @Override public void onCreate(SQLiteDatabase db) { try { db.execSQL(DATABASE_CREATE); } catch (SQLException e) { e.printStackTrace(); } } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { Log.w(TAG, "Upgrading database from version " + oldVersion + " to " + newVersion + ", which will destroy all old data"); db.execSQL("DROP TABLE IF EXISTS contacts"); onCreate(db); } } //---opens the database--- public DBAdapter open() throws SQLException { db = DBHelper.getWritableDatabase(); return this; } //---closes the database--- public void close() { DBHelper.close(); } //---insert a record into the database--- public long insertRecord(String title, String duedate, String course, String notes) { ContentValues initialValues = new ContentValues(); initialValues.put(KEY_TITLE, title); initialValues.put(KEY_DUEDATE, duedate); initialValues.put(KEY_COURSE, course); initialValues.put(KEY_NOTES, notes); return db.insert(DATABASE_TABLE, null, initialValues); } //---deletes a particular record--- public boolean deleteContact(long rowId) { return db.delete(DATABASE_TABLE, KEY_ROWID + "=" + rowId, null) > 0; } //---retrieves all the records--- public Cursor getAllRecords() { return db.query(DATABASE_TABLE, new String[] {KEY_ROWID, KEY_TITLE, KEY_DUEDATE, KEY_COURSE, KEY_NOTES}, null, null, null, null, null); } //---retrieves a particular record--- public Cursor getRecord(long rowId) throws SQLException { Cursor mCursor = db.query(true, DATABASE_TABLE, new String[] {KEY_ROWID, KEY_TITLE, KEY_DUEDATE, KEY_COURSE, KEY_NOTES}, KEY_ROWID + "=" + rowId, null, null, null, null, null); if (mCursor != null) { mCursor.moveToFirst(); } return mCursor; } //---updates a record--- public boolean updateRecord(long rowId, String title, String duedate, String course, String notes) { ContentValues args = new ContentValues(); args.put(KEY_TITLE, title); args.put(KEY_DUEDATE, duedate); args.put(KEY_COURSE, course); args.put(KEY_NOTES, notes); return db.update(DATABASE_TABLE, args, KEY_ROWID + "=" + rowId, null) > 0; } } addassignment code: package com.example.studentdatabase; public class addassignment extends Activity { DBAdapter db = new DBAdapter(this); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.add); } public void addAssignment(View v) { Log.d("test", "adding"); //get data from form EditText nameTxt = (EditText)findViewById(R.id.editTitle); EditText dateTxt = (EditText)findViewById(R.id.editDuedate); EditText courseTxt = (EditText)findViewById(R.id.editCourse); EditText notesTxt = (EditText)findViewById(R.id.editNotes); db.open(); long id = db.insertRecord(nameTxt.getText().toString(), dateTxt.getText().toString(), courseTxt.getText().toString(), notesTxt.getText().toString()); db.close(); nameTxt.setText(""); dateTxt.setText(""); courseTxt.setText(""); notesTxt.setText(""); Toast.makeText(addassignment.this,"Assignment Added", Toast.LENGTH_LONG).show(); } public void viewAssignments(View v) { Intent i = new Intent(this, MainActivity.class); startActivity(i); } } What is wrong here? Thanks in advance.

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  • add a from to backup routine

    - by Gerard Flynn
    hi how do you put a process bar and button onto this code i have class and want to add a gui on to the code using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Text; using System.Windows.Forms; using System.Data.SqlClient; using System.IO; using System.Threading; using Tamir.SharpSsh; using System.Security.Cryptography; using ICSharpCode.SharpZipLib.Checksums; using ICSharpCode.SharpZipLib.Zip; using ICSharpCode.SharpZipLib.GZip; namespace backup { public partial class Form1 : Form { public Form1() { InitializeComponent(); } /// <summary> /// Summary description for Class1. /// </summary> public class Backup { private string dbName; private string dbUsername; private string dbPassword; private static string baseDir; private string backupName; private static bool isBackup; private string keyString; private string ivString; private string[] backupDirs = new string[0]; private string[] excludeDirs = new string[0]; private ZipOutputStream zipOutputStream; private string backupFile; private string zipFile; private string encryptedFile; static void Main() { Backup.Log("BackupUtility loaded"); try { new Backup(); if (!isBackup) MessageBox.Show("Restore complete"); } catch (Exception e) { Backup.Log(e.ToString()); if (!isBackup) MessageBox.Show("Error restoring!\r\n" + e.Message); } } private void LoadAppSettings() { this.backupName = System.Configuration.ConfigurationSettings.AppSettings["BackupName"].ToString(); this.dbName = System.Configuration.ConfigurationSettings.AppSettings["DBName"].ToString(); this.dbUsername = System.Configuration.ConfigurationSettings.AppSettings["DBUsername"].ToString(); this.dbPassword = System.Configuration.ConfigurationSettings.AppSettings["DBPassword"].ToString(); //default to using where we are executing this assembly from Backup.baseDir = System.Reflection.Assembly.GetExecutingAssembly().Location.Substring(0, System.Reflection.Assembly.GetExecutingAssembly().Location.LastIndexOf("\\")) + "\\"; Backup.isBackup = bool.Parse(System.Configuration.ConfigurationSettings.AppSettings["IsBackup"].ToString()); this.keyString = System.Configuration.ConfigurationSettings.AppSettings["KeyString"].ToString(); this.ivString = System.Configuration.ConfigurationSettings.AppSettings["IVString"].ToString(); this.backupDirs = GetSetting("BackupDirs", ','); this.excludeDirs = GetSetting("ExcludeDirs", ','); } private string[] GetSetting(string settingName, char delimiter) { if (System.Configuration.ConfigurationSettings.AppSettings[settingName] != null) { string settingVal = System.Configuration.ConfigurationSettings.AppSettings[settingName].ToString(); if (settingVal.Length > 0) return settingVal.Split(delimiter); } return new string[0]; } public Backup() { this.LoadAppSettings(); if (isBackup) this.DoBackup(); else this.DoRestore(); Log("Finished"); } private void DoRestore() { System.Windows.Forms.OpenFileDialog fileDialog = new System.Windows.Forms.OpenFileDialog(); fileDialog.Title = "Choose .encrypted file"; fileDialog.Filter = "Encrypted files (*.encrypted)|*.encrypted|All files (*.*)|*.*"; fileDialog.InitialDirectory = Backup.baseDir; if (fileDialog.ShowDialog() == System.Windows.Forms.DialogResult.OK) { //string encryptedFile = GetFileName("encrypted"); string encryptedFile = fileDialog.FileName; string decryptedFile = this.GetDecryptedFilename(encryptedFile); //string originalFile = GetFileName("original"); this.Decrypt(encryptedFile, decryptedFile); //this.UnzipFile(decryptedFile, originalFile); } } //use the same filename as the backup except replace ".encrypted" with ".decrypted.zip" private string GetDecryptedFilename(string encryptedFile) { string name = encryptedFile.Substring(0, encryptedFile.LastIndexOf(".")); name += ".decrypted.zip"; return name; } private void DoBackup() { this.backupFile = GetFileName("bak"); this.zipFile = GetFileName("zip"); this.encryptedFile = GetFileName("encrypted"); this.DeleteFiles(); this.zipOutputStream = new ZipOutputStream(File.Create(zipFile)); try { //backup database first if (this.dbName.Length > 0) { this.BackupDB(backupFile); this.ZipFile(backupFile, this.GetName(backupFile)); } //zip any directories specified in config file this.ZipUserSpecifiedFilesAndDirectories(this.backupDirs); } finally { this.zipOutputStream.Finish(); this.zipOutputStream.Close(); } this.Encrypt(zipFile, encryptedFile); this.SCPFile(encryptedFile); this.DeleteFiles(); } /// <summary> /// Deletes any files created by the backup process, namely the DB backup file, /// the zip of all files backuped up, and the encrypred zip file /// </summary> private void DeleteFiles() { File.Delete(this.backupFile); File.Delete(this.zipFile); ///File.Delete(this.encryptedFile); } private void ZipUserSpecifiedFilesAndDirectories(string[] fileNames) { foreach (string fileName in fileNames) { string name = fileName.Trim(); if (name.Length > 0) { Log("Zipping " + name); this.ZipFile(name, this.GetNameFromDir(name)); } } } private void SCPFile(string inputPath) { string sshServer = System.Configuration.ConfigurationSettings.AppSettings["SSHServer"].ToString(); string sshUsername = System.Configuration.ConfigurationSettings.AppSettings["SSHUsername"].ToString(); string sshPassword = System.Configuration.ConfigurationSettings.AppSettings["SSHPassword"].ToString(); if (sshServer.Length > 0 && sshUsername.Length > 0 && sshPassword.Length > 0) { Scp scp = new Scp(sshServer, sshUsername, sshPassword); //Copy a file from local machine to remote SSH server scp.Connect(); Log("Connected to " + sshServer); //scp.Put(inputPath, "/home/wal/temp.txt"); scp.Put(inputPath, GetName(inputPath)); scp.Close(); } else { Log("Not SCP as missing login details"); } } private string GetName(string inputPath) { FileInfo info = new FileInfo(inputPath); return info.Name; } private string GetNameFromDir(string inputPath) { DirectoryInfo info = new DirectoryInfo(inputPath); return info.Name; } private static void Log(string msg) { try { string toLog = DateTime.Now.ToString() + ": " + msg; System.Diagnostics.Debug.WriteLine(toLog); System.IO.FileStream fs = new System.IO.FileStream(baseDir + "app.log", System.IO.FileMode.OpenOrCreate, System.IO.FileAccess.ReadWrite); System.IO.StreamWriter m_streamWriter = new System.IO.StreamWriter(fs); m_streamWriter.BaseStream.Seek(0, System.IO.SeekOrigin.End); m_streamWriter.WriteLine(toLog); m_streamWriter.Flush(); m_streamWriter.Close(); fs.Close(); } catch (Exception e) { Console.WriteLine(e.ToString()); } } private byte[] GetFileBytes(string path) { FileStream stream = new FileStream(path, FileMode.Open); byte[] bytes = new byte[stream.Length]; stream.Read(bytes, 0, bytes.Length); stream.Close(); return bytes; } private void WriteFileBytes(byte[] bytes, string path) { FileStream stream = new FileStream(path, FileMode.Create); stream.Write(bytes, 0, bytes.Length); stream.Close(); } private void UnzipFile(string inputPath, string outputPath) { ZipInputStream zis = new ZipInputStream(File.OpenRead(inputPath)); ZipEntry theEntry = zis.GetNextEntry(); FileStream streamWriter = File.Create(outputPath); int size = 2048; byte[] data = new byte[2048]; while (true) { size = zis.Read(data, 0, data.Length); if (size > 0) { streamWriter.Write(data, 0, size); } else { break; } } streamWriter.Close(); zis.Close(); } private bool ExcludeDir(string dirName) { foreach (string excludeDir in this.excludeDirs) { if (dirName == excludeDir) return true; } return false; } private void ZipFile(string inputPath, string zipName) { FileAttributes fa = File.GetAttributes(inputPath); if ((fa & FileAttributes.Directory) != 0) { string dirName = zipName + "/"; ZipEntry entry1 = new ZipEntry(dirName); this.zipOutputStream.PutNextEntry(entry1); string[] subDirs = Directory.GetDirectories(inputPath); //create directories first foreach (string subDir in subDirs) { DirectoryInfo info = new DirectoryInfo(subDir); string name = info.Name; if (this.ExcludeDir(name)) Log("Excluding " + dirName + name); else this.ZipFile(subDir, dirName + name); } //then store files string[] fileNames = Directory.GetFiles(inputPath); foreach (string fileName in fileNames) { FileInfo info = new FileInfo(fileName); string name = info.Name; this.ZipFile(fileName, dirName + name); } } else { Crc32 crc = new Crc32(); this.zipOutputStream.SetLevel(6); // 0 - store only to 9 - means best compression FileStream fs = null; try { fs = File.OpenRead(inputPath); } catch (IOException ioEx) { Log("WARNING! " + ioEx.Message);//might be in use, skip file in this case } if (fs != null) { byte[] buffer = new byte[fs.Length]; fs.Read(buffer, 0, buffer.Length); ZipEntry entry = new ZipEntry(zipName); entry.DateTime = DateTime.Now; // set Size and the crc, because the information // about the size and crc should be stored in the header // if it is not set it is automatically written in the footer. // (in this case size == crc == -1 in the header) // Some ZIP programs have problems with zip files that don't store // the size and crc in the header. entry.Size = fs.Length; fs.Close(); crc.Reset(); crc.Update(buffer); entry.Crc = crc.Value; this.zipOutputStream.PutNextEntry(entry); this.zipOutputStream.Write(buffer, 0, buffer.Length); } } } private void Encrypt(string inputPath, string outputPath) { RijndaelManaged rijndaelManaged = new RijndaelManaged(); byte[] encrypted; byte[] toEncrypt; //Create a new key and initialization vector. //myRijndael.GenerateKey(); //myRijndael.GenerateIV(); /*des.GenerateKey(); des.GenerateIV(); string temp1 = Convert.ToBase64String(des.Key); string temp2 = Convert.ToBase64String(des.IV);*/ //Get the key and IV. byte[] key = Convert.FromBase64String(keyString); byte[] IV = Convert.FromBase64String(ivString); //Get an encryptor. ICryptoTransform encryptor = rijndaelManaged.CreateEncryptor(key, IV); //Encrypt the data. MemoryStream msEncrypt = new MemoryStream(); CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write); //Convert the data to a byte array. toEncrypt = this.GetFileBytes(inputPath); //Write all data to the crypto stream and flush it. csEncrypt.Write(toEncrypt, 0, toEncrypt.Length); csEncrypt.FlushFinalBlock(); //Get encrypted array of bytes. encrypted = msEncrypt.ToArray(); WriteFileBytes(encrypted, outputPath); } private void Decrypt(string inputPath, string outputPath) { RijndaelManaged myRijndael = new RijndaelManaged(); //DES des = new DESCryptoServiceProvider(); byte[] key = Convert.FromBase64String(keyString); byte[] IV = Convert.FromBase64String(ivString); byte[] encrypted = this.GetFileBytes(inputPath); byte[] fromEncrypt; //Get a decryptor that uses the same key and IV as the encryptor. ICryptoTransform decryptor = myRijndael.CreateDecryptor(key, IV); //Now decrypt the previously encrypted message using the decryptor // obtained in the above step. MemoryStream msDecrypt = new MemoryStream(encrypted); CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read); fromEncrypt = new byte[encrypted.Length]; //Read the data out of the crypto stream. int bytesRead = csDecrypt.Read(fromEncrypt, 0, fromEncrypt.Length); byte[] readBytes = new byte[bytesRead]; Array.Copy(fromEncrypt, 0, readBytes, 0, bytesRead); this.WriteFileBytes(readBytes, outputPath); } private string GetFileName(string extension) { return baseDir + backupName + "_" + DateTime.Now.ToString("yyyyMMdd") + "." + extension; } private void BackupDB(string backupPath) { string sql = @"DECLARE @Date VARCHAR(300), @Dir VARCHAR(4000) --Get today date SET @Date = CONVERT(VARCHAR, GETDATE(), 112) --Set the directory where the back up file is stored SET @Dir = '"; sql += backupPath; sql += @"' --create a 'device' to write to first EXEC sp_addumpdevice 'disk', 'temp_device', @Dir --now do the backup BACKUP DATABASE " + this.dbName; sql += @" TO temp_device WITH FORMAT --Drop the device EXEC sp_dropdevice 'temp_device' "; //Console.WriteLine("sql="+sql); Backup.Log("Starting backup of " + this.dbName); ExecuteSQL(sql); } /// <summary> /// Executes the specified SQL /// Returns true if no errors were encountered during execution /// </summary> /// <param name="procedureName"></param> private void ExecuteSQL(string sql) { SqlConnection conn = new SqlConnection(this.GetDBConnectString()); try { SqlCommand comm = new SqlCommand(sql, conn); conn.Open(); comm.ExecuteNonQuery(); } finally { conn.Close(); } } private string GetDBConnectString() { StringBuilder builder = new StringBuilder(); builder.Append("Data Source=127.0.0.1; User ID="); builder.Append(this.dbUsername); builder.Append("; Password="); builder.Append(this.dbPassword); builder.Append("; Initial Catalog="); builder.Append(this.dbName); builder.Append(";Connect Timeout=30"); return builder.ToString(); } } } }

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  • web.xml not reloading in tomcat even after stop/start

    - by ajay
    This is in relation to:- http://stackoverflow.com/questions/2576514/basic-tomcat-servlet-error I changed my web.xml file, did ant compile , all, /etc/init.d/tomcat stop , start Even then my web.xml file in tomcat deployment is still unchanged. This is build.properties file:- app.name=hello catalina.home=/usr/local/tomcat manager.username=admin manager.password=admin This is my build.xml file. Is there something wrong with this:- <!-- 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. --> <!-- General purpose build script for web applications and web services, including enhanced support for deploying directly to a Tomcat 6 based server. This build script assumes that the source code of your web application is organized into the following subdirectories underneath the source code directory from which you execute the build script: docs Static documentation files to be copied to the "docs" subdirectory of your distribution. src Java source code (and associated resource files) to be compiled to the "WEB-INF/classes" subdirectory of your web applicaiton. web Static HTML, JSP, and other content (such as image files), including the WEB-INF subdirectory and its configuration file contents. $Id: build.xml.txt 562814 2007-08-05 03:52:04Z markt $ --> <!-- A "project" describes a set of targets that may be requested when Ant is executed. The "default" attribute defines the target which is executed if no specific target is requested, and the "basedir" attribute defines the current working directory from which Ant executes the requested task. This is normally set to the current working directory. --> <project name="My Project" default="compile" basedir="."> <!-- ===================== Property Definitions =========================== --> <!-- Each of the following properties are used in the build script. Values for these properties are set by the first place they are defined, from the following list: * Definitions on the "ant" command line (ant -Dfoo=bar compile). * Definitions from a "build.properties" file in the top level source directory of this application. * Definitions from a "build.properties" file in the developer's home directory. * Default definitions in this build.xml file. You will note below that property values can be composed based on the contents of previously defined properties. This is a powerful technique that helps you minimize the number of changes required when your development environment is modified. Note that property composition is allowed within "build.properties" files as well as in the "build.xml" script. --> <property file="build.properties"/> <property file="${user.home}/build.properties"/> <!-- ==================== File and Directory Names ======================== --> <!-- These properties generally define file and directory names (or paths) that affect where the build process stores its outputs. app.name Base name of this application, used to construct filenames and directories. Defaults to "myapp". app.path Context path to which this application should be deployed (defaults to "/" plus the value of the "app.name" property). app.version Version number of this iteration of the application. build.home The directory into which the "prepare" and "compile" targets will generate their output. Defaults to "build". catalina.home The directory in which you have installed a binary distribution of Tomcat 6. This will be used by the "deploy" target. dist.home The name of the base directory in which distribution files are created. Defaults to "dist". manager.password The login password of a user that is assigned the "manager" role (so that he or she can execute commands via the "/manager" web application) manager.url The URL of the "/manager" web application on the Tomcat installation to which we will deploy web applications and web services. manager.username The login username of a user that is assigned the "manager" role (so that he or she can execute commands via the "/manager" web application) --> <property name="app.name" value="myapp"/> <property name="app.path" value="/${app.name}"/> <property name="app.version" value="0.1-dev"/> <property name="build.home" value="${basedir}/build"/> <property name="catalina.home" value="../../../.."/> <!-- UPDATE THIS! --> <property name="dist.home" value="${basedir}/dist"/> <property name="docs.home" value="${basedir}/docs"/> <property name="manager.url" value="http://localhost:8080/manager"/> <property name="src.home" value="${basedir}/src"/> <property name="web.home" value="${basedir}/web"/> <!-- ==================== External Dependencies =========================== --> <!-- Use property values to define the locations of external JAR files on which your application will depend. In general, these values will be used for two purposes: * Inclusion on the classpath that is passed to the Javac compiler * Being copied into the "/WEB-INF/lib" directory during execution of the "deploy" target. Because we will automatically include all of the Java classes that Tomcat 6 exposes to web applications, we will not need to explicitly list any of those dependencies. You only need to worry about external dependencies for JAR files that you are going to include inside your "/WEB-INF/lib" directory. --> <!-- Dummy external dependency --> <!-- <property name="foo.jar" value="/path/to/foo.jar"/> --> <!-- ==================== Compilation Classpath =========================== --> <!-- Rather than relying on the CLASSPATH environment variable, Ant includes features that makes it easy to dynamically construct the classpath you need for each compilation. The example below constructs the compile classpath to include the servlet.jar file, as well as the other components that Tomcat makes available to web applications automatically, plus anything that you explicitly added. --> <path id="compile.classpath"> <!-- Include all JAR files that will be included in /WEB-INF/lib --> <!-- *** CUSTOMIZE HERE AS REQUIRED BY YOUR APPLICATION *** --> <!-- <pathelement location="${foo.jar}"/> --> <!-- Include all elements that Tomcat exposes to applications --> <fileset dir="${catalina.home}/bin"> <include name="*.jar"/> </fileset> <pathelement location="${catalina.home}/lib"/> <fileset dir="${catalina.home}/lib"> <include name="*.jar"/> </fileset> </path> <!-- ================== Custom Ant Task Definitions ======================= --> <!-- These properties define custom tasks for the Ant build tool that interact with the "/manager" web application installed with Tomcat 6. Before they can be successfully utilized, you must perform the following steps: - Copy the file "lib/catalina-ant.jar" from your Tomcat 6 installation into the "lib" directory of your Ant installation. - Create a "build.properties" file in your application's top-level source directory (or your user login home directory) that defines appropriate values for the "manager.password", "manager.url", and "manager.username" properties described above. For more information about the Manager web application, and the functionality of these tasks, see <http://localhost:8080/tomcat-docs/manager-howto.html>. --> <taskdef resource="org/apache/catalina/ant/catalina.tasks" classpathref="compile.classpath"/> <!-- ==================== Compilation Control Options ==================== --> <!-- These properties control option settings on the Javac compiler when it is invoked using the <javac> task. compile.debug Should compilation include the debug option? compile.deprecation Should compilation include the deprecation option? compile.optimize Should compilation include the optimize option? --> <property name="compile.debug" value="true"/> <property name="compile.deprecation" value="false"/> <property name="compile.optimize" value="true"/> <!-- ==================== All Target ====================================== --> <!-- The "all" target is a shortcut for running the "clean" target followed by the "compile" target, to force a complete recompile. --> <target name="all" depends="clean,compile" description="Clean build and dist directories, then compile"/> <!-- ==================== Clean Target ==================================== --> <!-- The "clean" target deletes any previous "build" and "dist" directory, so that you can be ensured the application can be built from scratch. --> <target name="clean" description="Delete old build and dist directories"> <delete dir="${build.home}"/> <delete dir="${dist.home}"/> </target> <!-- ==================== Compile Target ================================== --> <!-- The "compile" target transforms source files (from your "src" directory) into object files in the appropriate location in the build directory. This example assumes that you will be including your classes in an unpacked directory hierarchy under "/WEB-INF/classes". --> <target name="compile" depends="prepare" description="Compile Java sources"> <!-- Compile Java classes as necessary --> <mkdir dir="${build.home}/WEB-INF/classes"/> <javac srcdir="${src.home}" destdir="${build.home}/WEB-INF/classes" debug="${compile.debug}" deprecation="${compile.deprecation}" optimize="${compile.optimize}"> <classpath refid="compile.classpath"/> </javac> <!-- Copy application resources --> <copy todir="${build.home}/WEB-INF/classes"> <fileset dir="${src.home}" excludes="**/*.java"/> </copy> </target> <!-- ==================== Dist Target ===================================== --> <!-- The "dist" target creates a binary distribution of your application in a directory structure ready to be archived in a tar.gz or zip file. Note that this target depends on two others: * "compile" so that the entire web application (including external dependencies) will have been assembled * "javadoc" so that the application Javadocs will have been created --> <target name="dist" depends="compile,javadoc" description="Create binary distribution"> <!-- Copy documentation subdirectories --> <mkdir dir="${dist.home}/docs"/> <copy todir="${dist.home}/docs"> <fileset dir="${docs.home}"/> </copy> <!-- Create application JAR file --> <jar jarfile="${dist.home}/${app.name}-${app.version}.war" basedir="${build.home}"/> <!-- Copy additional files to ${dist.home} as necessary --> </target> <!-- ==================== Install Target ================================== --> <!-- The "install" target tells the specified Tomcat 6 installation to dynamically install this web application and make it available for execution. It does *not* cause the existence of this web application to be remembered across Tomcat restarts; if you restart the server, you will need to re-install all this web application. If you have already installed this application, and simply want Tomcat to recognize that you have updated Java classes (or the web.xml file), use the "reload" target instead. NOTE: This target will only succeed if it is run from the same server that Tomcat is running on. NOTE: This is the logical opposite of the "remove" target. --> <target name="install" depends="compile" description="Install application to servlet container"> <deploy url="${manager.url}" username="${manager.username}" password="${manager.password}" path="${app.path}" localWar="file://${build.home}"/> </target> <!-- ==================== Javadoc Target ================================== --> <!-- The "javadoc" target creates Javadoc API documentation for the Java classes included in your application. Normally, this is only required when preparing a distribution release, but is available as a separate target in case the developer wants to create Javadocs independently. --> <target name="javadoc" depends="compile" description="Create Javadoc API documentation"> <mkdir dir="${dist.home}/docs/api"/> <javadoc sourcepath="${src.home}" destdir="${dist.home}/docs/api" packagenames="*"> <classpath refid="compile.classpath"/> </javadoc> </target> <!-- ====================== List Target =================================== --> <!-- The "list" target asks the specified Tomcat 6 installation to list the currently running web applications, either loaded at startup time or installed dynamically. It is useful to determine whether or not the application you are currently developing has been installed. --> <target name="list" description="List installed applications on servlet container"> <list url="${manager.url}" username="${manager.username}" password="${manager.password}"/> </target> <!-- ==================== Prepare Target ================================== --> <!-- The "prepare" target is used to create the "build" destination directory, and copy the static contents of your web application to it. If you need to copy static files from external dependencies, you can customize the contents of this task. Normally, this task is executed indirectly when needed. --> <target name="prepare"> <!-- Create build directories as needed --> <mkdir dir="${build.home}"/> <mkdir dir="${build.home}/WEB-INF"/> <mkdir dir="${build.home}/WEB-INF/classes"/> <!-- Copy static content of this web application --> <copy todir="${build.home}"> <fileset dir="${web.home}"/> </copy> <!-- Copy external dependencies as required --> <!-- *** CUSTOMIZE HERE AS REQUIRED BY YOUR APPLICATION *** --> <mkdir dir="${build.home}/WEB-INF/lib"/> <!-- <copy todir="${build.home}/WEB-INF/lib" file="${foo.jar}"/> --> <!-- Copy static files from external dependencies as needed --> <!-- *** CUSTOMIZE HERE AS REQUIRED BY YOUR APPLICATION *** --> </target> <!-- ==================== Reload Target =================================== --> <!-- The "reload" signals the specified application Tomcat 6 to shut itself down and reload. This can be useful when the web application context is not reloadable and you have updated classes or property files in the /WEB-INF/classes directory or when you have added or updated jar files in the /WEB-INF/lib directory. NOTE: The /WEB-INF/web.xml web application configuration file is not reread on a reload. If you have made changes to your web.xml file you must stop then start the web application. --> <target name="reload" depends="compile" description="Reload application on servlet container"> <reload url="${manager.url}" username="${manager.username}" password="${manager.password}" path="${app.path}"/> </target> <!-- ==================== Remove Target =================================== --> <!-- The "remove" target tells the specified Tomcat 6 installation to dynamically remove this web application from service. NOTE: This is the logical opposite of the "install" target. --> <target name="remove" description="Remove application on servlet container"> <undeploy url="${manager.url}" username="${manager.username}" password="${manager.password}" path="${app.path}"/> </target> </project>

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  • Conway's Game of Life - C++ and Qt

    - by Jeff Bridge
    I've done all of the layouts and have most of the code written even. But, I'm stuck in two places. 1) I'm not quite sure how to set up the timer. Am I using it correctly in the gridwindow class? And, am I used the timer functions/signals/slots correctly with the other gridwindow functions. 2) In GridWindow's timerFired() function, I'm having trouble checking/creating the vector-vectors. I wrote out in the comments in that function exactly what I am trying to do. Any help would be much appreciated. main.cpp // Main file for running the grid window application. #include <QApplication> #include "gridwindow.h" //#include "timerwindow.h" #include <stdexcept> #include <string> #include <fstream> #include <sstream> #include <iostream> void Welcome(); // Welcome Function - Prints upon running program; outputs program name, student name/id, class section. void Rules(); // Rules Function: Prints the rules for Conway's Game of Life. using namespace std; // A simple main method to create the window class and then pop it up on the screen. int main(int argc, char *argv[]) { Welcome(); // Calls Welcome function to print student/assignment info. Rules(); // Prints Conway's Game Rules. QApplication app(argc, argv); // Creates the overall windowed application. int rows = 25, cols = 35; //The number of rows & columns in the game grid. GridWindow widget(NULL,rows,cols); // Creates the actual window (for the grid). widget.show(); // Shows the window on the screen. return app.exec(); // Goes into visual loop; starts executing GUI. } // Welcome Function: Prints my name/id, my class number, the assignment, and the program name. void Welcome() { cout << endl; cout << "-------------------------------------------------------------------------------------------------" << endl; cout << "Name/ID - Gabe Audick #7681539807" << endl; cout << "Class/Assignment - CSCI-102 Disccusion 29915: Homework Assignment #4" << endl; cout << "-------------------------------------------------------------------------------------------------" << endl << endl; } // Rules Function: Prints the rules for Conway's Game of Life. void Rules() { cout << "Welcome to Conway's Game of Life." << endl; cout << "Game Rules:" << endl; cout << "\t 1) Any living cell with fewer than two living neighbours dies, as if caused by underpopulation." << endl; cout << "\t 2) Any live cell with more than three live neighbours dies, as if by overcrowding." << endl; cout << "\t 3) Any live cell with two or three live neighbours lives on to the next generation." << endl; cout << "\t 4) Any dead cell with exactly three live neighbours becomes a live cell." << endl << endl; cout << "Enjoy." << endl << endl; } gridcell.h // A header file for a class representing a single cell in a grid of cells. #ifndef GRIDCELL_H_ #define GRIDCELL_H_ #include <QPalette> #include <QColor> #include <QPushButton> #include <Qt> #include <QWidget> #include <QFrame> #include <QHBoxLayout> #include <iostream> // An enum representing the two different states a cell can have. enum CellType { DEAD, // DEAD = Dead Cell. --> Color = White. LIVE // LIVE = Living Cell. ---> Color = White. }; /* Class: GridCell. A class representing a single cell in a grid. Each cell is implemented as a QT QFrame that contains a single QPushButton. The button is sized so that it takes up the entire frame. Each cell also keeps track of what type of cell it is based on the CellType enum. */ class GridCell : public QFrame { Q_OBJECT // Macro allowing us to have signals & slots on this object. private: QPushButton* button; // The button inside the cell that gives its clickability. CellType type; // The type of cell (DEAD or LIVE.) public slots: void handleClick(); // Callback for handling a click on the current cell. void setType(CellType type); // Cell type mutator. Calls the "redrawCell" function. signals: void typeChanged(CellType type); // Signal to notify listeners when the cell type has changed. public: GridCell(QWidget *parent = NULL); // Constructor for creating a cell. Takes parent widget or default parent to NULL. virtual ~GridCell(); // Destructor. void redrawCell(); // Redraws cell: Sets new type/color. CellType getType() const; //Simple getter for the cell type. private: Qt::GlobalColor getColorForCellType(); // Helper method. Returns color that cell should be based from its value. }; #endif gridcell.cpp #include <iostream> #include "gridcell.h" #include "utility.h" using namespace std; // Constructor: Creates a grid cell. GridCell::GridCell(QWidget *parent) : QFrame(parent) { this->type = DEAD; // Default: Cell is DEAD (white). setFrameStyle(QFrame::Box); // Set the frame style. This is what gives each box its black border. this->button = new QPushButton(this); //Creates button that fills entirety of each grid cell. this->button->setSizePolicy(QSizePolicy::Expanding,QSizePolicy::Expanding); // Expands button to fill space. this->button->setMinimumSize(19,19); //width,height // Min height and width of button. QHBoxLayout *layout = new QHBoxLayout(); //Creates a simple layout to hold our button and add the button to it. layout->addWidget(this->button); setLayout(layout); layout->setStretchFactor(this->button,1); // Lets the buttons expand all the way to the edges of the current frame with no space leftover layout->setContentsMargins(0,0,0,0); layout->setSpacing(0); connect(this->button,SIGNAL(clicked()),this,SLOT(handleClick())); // Connects clicked signal with handleClick slot. redrawCell(); // Calls function to redraw (set new type for) the cell. } // Basic destructor. GridCell::~GridCell() { delete this->button; } // Accessor for the cell type. CellType GridCell::getType() const { return(this->type); } // Mutator for the cell type. Also has the side effect of causing the cell to be redrawn on the GUI. void GridCell::setType(CellType type) { this->type = type; redrawCell(); } // Handler slot for button clicks. This method is called whenever the user clicks on this cell in the grid. void GridCell::handleClick() { // When clicked on... if(this->type == DEAD) // If type is DEAD (white), change to LIVE (black). type = LIVE; else type = DEAD; // If type is LIVE (black), change to DEAD (white). setType(type); // Sets new type (color). setType Calls redrawCell() to recolor. } // Method to check cell type and return the color of that type. Qt::GlobalColor GridCell::getColorForCellType() { switch(this->type) { default: case DEAD: return Qt::white; case LIVE: return Qt::black; } } // Helper method. Forces current cell to be redrawn on the GUI. Called whenever the setType method is invoked. void GridCell::redrawCell() { Qt::GlobalColor gc = getColorForCellType(); //Find out what color this cell should be. this->button->setPalette(QPalette(gc,gc)); //Force the button in the cell to be the proper color. this->button->setAutoFillBackground(true); this->button->setFlat(true); //Force QT to NOT draw the borders on the button } gridwindow.h // A header file for a QT window that holds a grid of cells. #ifndef GRIDWINDOW_H_ #define GRIDWINDOW_H_ #include <vector> #include <QWidget> #include <QTimer> #include <QGridLayout> #include <QLabel> #include <QApplication> #include "gridcell.h" /* class GridWindow: This is the class representing the whole window that comes up when this program runs. It contains a header section with a title, a middle section of MxN cells and a bottom section with buttons. */ class GridWindow : public QWidget { Q_OBJECT // Macro to allow this object to have signals & slots. private: std::vector<std::vector<GridCell*> > cells; // A 2D vector containing pointers to all the cells in the grid. QLabel *title; // A pointer to the Title text on the window. QTimer *timer; // Creates timer object. public slots: void handleClear(); // Handler function for clicking the Clear button. void handleStart(); // Handler function for clicking the Start button. void handlePause(); // Handler function for clicking the Pause button. void timerFired(); // Method called whenever timer fires. public: GridWindow(QWidget *parent = NULL,int rows=3,int cols=3); // Constructor. virtual ~GridWindow(); // Destructor. std::vector<std::vector<GridCell*> >& getCells(); // Accessor for the array of grid cells. private: QHBoxLayout* setupHeader(); // Helper function to construct the GUI header. QGridLayout* setupGrid(int rows,int cols); // Helper function to constructor the GUI's grid. QHBoxLayout* setupButtonRow(); // Helper function to setup the row of buttons at the bottom. }; #endif gridwindow.cpp #include <iostream> #include "gridwindow.h" using namespace std; // Constructor for window. It constructs the three portions of the GUI and lays them out vertically. GridWindow::GridWindow(QWidget *parent,int rows,int cols) : QWidget(parent) { QHBoxLayout *header = setupHeader(); // Setup the title at the top. QGridLayout *grid = setupGrid(rows,cols); // Setup the grid of colored cells in the middle. QHBoxLayout *buttonRow = setupButtonRow(); // Setup the row of buttons across the bottom. QVBoxLayout *layout = new QVBoxLayout(); // Puts everything together. layout->addLayout(header); layout->addLayout(grid); layout->addLayout(buttonRow); setLayout(layout); } // Destructor. GridWindow::~GridWindow() { delete title; } // Builds header section of the GUI. QHBoxLayout* GridWindow::setupHeader() { QHBoxLayout *header = new QHBoxLayout(); // Creates horizontal box. header->setAlignment(Qt::AlignHCenter); this->title = new QLabel("CONWAY'S GAME OF LIFE",this); // Creates big, bold, centered label (title): "Conway's Game of Life." this->title->setAlignment(Qt::AlignHCenter); this->title->setFont(QFont("Arial", 32, QFont::Bold)); header->addWidget(this->title); // Adds widget to layout. return header; // Returns header to grid window. } // Builds the grid of cells. This method populates the grid's 2D array of GridCells with MxN cells. QGridLayout* GridWindow::setupGrid(int rows,int cols) { QGridLayout *grid = new QGridLayout(); // Creates grid layout. grid->setHorizontalSpacing(0); // No empty spaces. Cells should be contiguous. grid->setVerticalSpacing(0); grid->setSpacing(0); grid->setAlignment(Qt::AlignHCenter); for(int i=0; i < rows; i++) //Each row is a vector of grid cells. { std::vector<GridCell*> row; // Creates new vector for current row. cells.push_back(row); for(int j=0; j < cols; j++) { GridCell *cell = new GridCell(); // Creates and adds new cell to row. cells.at(i).push_back(cell); grid->addWidget(cell,i,j); // Adds to cell to grid layout. Column expands vertically. grid->setColumnStretch(j,1); } grid->setRowStretch(i,1); // Sets row expansion horizontally. } return grid; // Returns grid. } // Builds footer section of the GUI. QHBoxLayout* GridWindow::setupButtonRow() { QHBoxLayout *buttonRow = new QHBoxLayout(); // Creates horizontal box for buttons. buttonRow->setAlignment(Qt::AlignHCenter); // Clear Button - Clears cell; sets them all to DEAD/white. QPushButton *clearButton = new QPushButton("CLEAR"); clearButton->setFixedSize(100,25); connect(clearButton, SIGNAL(clicked()), this, SLOT(handleClear())); buttonRow->addWidget(clearButton); // Start Button - Starts game when user clicks. Or, resumes game after being paused. QPushButton *startButton = new QPushButton("START/RESUME"); startButton->setFixedSize(100,25); connect(startButton, SIGNAL(clicked()), this, SLOT(handleStart())); buttonRow->addWidget(startButton); // Pause Button - Pauses simulation of game. QPushButton *pauseButton = new QPushButton("PAUSE"); pauseButton->setFixedSize(100,25); connect(pauseButton, SIGNAL(clicked()), this, SLOT(handlePause())); buttonRow->addWidget(pauseButton); // Quit Button - Exits program. QPushButton *quitButton = new QPushButton("EXIT"); quitButton->setFixedSize(100,25); connect(quitButton, SIGNAL(clicked()), qApp, SLOT(quit())); buttonRow->addWidget(quitButton); return buttonRow; // Returns bottom of layout. } /* SLOT method for handling clicks on the "clear" button. Receives "clicked" signals on the "Clear" button and sets all cells to DEAD. */ void GridWindow::handleClear() { for(unsigned int row=0; row < cells.size(); row++) // Loops through current rows' cells. { for(unsigned int col=0; col < cells[row].size(); col++) { GridCell *cell = cells[row][col]; // Grab the current cell & set its value to dead. cell->setType(DEAD); } } } /* SLOT method for handling clicks on the "start" button. Receives "clicked" signals on the "start" button and begins game simulation. */ void GridWindow::handleStart() { this->timer = new QTimer(this); // Creates new timer. connect(this->timer, SIGNAL(timeout()), this, SLOT(timerFired())); // Connect "timerFired" method class to the "timeout" signal fired by the timer. this->timer->start(500); // Timer to fire every 500 milliseconds. } /* SLOT method for handling clicks on the "pause" button. Receives "clicked" signals on the "pause" button and stops the game simulation. */ void GridWindow::handlePause() { this->timer->stop(); // Stops the timer. delete this->timer; // Deletes timer. } // Accessor method - Gets the 2D vector of grid cells. std::vector<std::vector<GridCell*> >& GridWindow::getCells() { return this->cells; } void GridWindow::timerFired() { // I'm not sure how to write this code. // I want to take the original vector-vector, and also make a new, empty vector-vector of the same size. // I would then go through the code below with the original vector, and apply the rules to the new vector-vector. // Finally, I would make the new vector-vecotr the original vector-vector. (That would be one step in the simulation.) cout << cells[1][2]; /* for (unsigned int m = 0; m < original.size(); m++) { for (unsigned int n = 0; n < original.at(m).size(); n++) { unsigned int neighbors = 0; //Begin counting number of neighbors. if (original[m-1][n-1].getType() == LIVE) // If a cell next to [i][j] is LIVE, add one to the neighbor count. neighbors += 1; if (original[m-1][n].getType() == LIVE) neighbors += 1; if (original[m-1][n+1].getType() == LIVE) neighbors += 1; if (original[m][n-1].getType() == LIVE) neighbors += 1; if (original[m][n+1].getType() == LIVE) neighbors += 1; if (original[m+1][n-1].getType() == LIVE) neighbors += 1; if (original[m+1][n].getType() == LIVE) neighbors += 1; if (original[m+1][n+1].getType() == LIVE) neighbors += 1; if (original[m][n].getType() == LIVE && neighbors < 2) // Apply game rules to cells: Create new, updated grid with the roundtwo vector. roundtwo[m][n].setType(LIVE); else if (original[m][n].getType() == LIVE && neighbors > 3) roundtwo[m][n].setType(DEAD); else if (original[m][n].getType() == LIVE && (neighbors == 2 || neighbors == 3)) roundtwo[m][n].setType(LIVE); else if (original[m][n].getType() == DEAD && neighbors == 3) roundtwo[m][n].setType(LIVE); } }*/ }

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  • C++ - Conway's Game of Life & Stepping Backwards

    - by Gabe
    I was able to create a version Conway's Game of Life that either stepped forward each click, or just ran forward using a timer. (I'm doing this using Qt.) Now, I need to be able to save all previous game grids, so that I can step backwards by clicking a button. I'm trying to use a stack, and it seems like I'm pushing the old gridcells onto the stack correctly. But when I run it in QT, the grids don't change when I click BACK. I've tried different things for the last three hours, to no avail. Any ideas? gridwindow.cpp - My problem should be in here somewhere. Probably the handleBack() func. #include <iostream> #include "gridwindow.h" using namespace std; // Constructor for window. It constructs the three portions of the GUI and lays them out vertically. GridWindow::GridWindow(QWidget *parent,int rows,int cols) : QWidget(parent) { QHBoxLayout *header = setupHeader(); // Setup the title at the top. QGridLayout *grid = setupGrid(rows,cols); // Setup the grid of colored cells in the middle. QHBoxLayout *buttonRow = setupButtonRow(); // Setup the row of buttons across the bottom. QVBoxLayout *layout = new QVBoxLayout(); // Puts everything together. layout->addLayout(header); layout->addLayout(grid); layout->addLayout(buttonRow); setLayout(layout); } // Destructor. GridWindow::~GridWindow() { delete title; } // Builds header section of the GUI. QHBoxLayout* GridWindow::setupHeader() { QHBoxLayout *header = new QHBoxLayout(); // Creates horizontal box. header->setAlignment(Qt::AlignHCenter); this->title = new QLabel("CONWAY'S GAME OF LIFE",this); // Creates big, bold, centered label (title): "Conway's Game of Life." this->title->setAlignment(Qt::AlignHCenter); this->title->setFont(QFont("Arial", 32, QFont::Bold)); header->addWidget(this->title); // Adds widget to layout. return header; // Returns header to grid window. } // Builds the grid of cells. This method populates the grid's 2D array of GridCells with MxN cells. QGridLayout* GridWindow::setupGrid(int rows,int cols) { isRunning = false; QGridLayout *grid = new QGridLayout(); // Creates grid layout. grid->setHorizontalSpacing(0); // No empty spaces. Cells should be contiguous. grid->setVerticalSpacing(0); grid->setSpacing(0); grid->setAlignment(Qt::AlignHCenter); for(int i=0; i < rows; i++) //Each row is a vector of grid cells. { std::vector<GridCell*> row; // Creates new vector for current row. cells.push_back(row); for(int j=0; j < cols; j++) { GridCell *cell = new GridCell(); // Creates and adds new cell to row. cells.at(i).push_back(cell); grid->addWidget(cell,i,j); // Adds to cell to grid layout. Column expands vertically. grid->setColumnStretch(j,1); } grid->setRowStretch(i,1); // Sets row expansion horizontally. } return grid; // Returns grid. } // Builds footer section of the GUI. QHBoxLayout* GridWindow::setupButtonRow() { QHBoxLayout *buttonRow = new QHBoxLayout(); // Creates horizontal box for buttons. buttonRow->setAlignment(Qt::AlignHCenter); // Clear Button - Clears cell; sets them all to DEAD/white. QPushButton *clearButton = new QPushButton("CLEAR"); clearButton->setFixedSize(100,25); connect(clearButton, SIGNAL(clicked()), this, SLOT(handlePause())); // Pauses timer before clearing. connect(clearButton, SIGNAL(clicked()), this, SLOT(handleClear())); // Connects to clear function to make all cells DEAD/white. buttonRow->addWidget(clearButton); // Forward Button - Steps one step forward. QPushButton *forwardButton = new QPushButton("FORWARD"); forwardButton->setFixedSize(100,25); connect(forwardButton, SIGNAL(clicked()), this, SLOT(handleForward())); // Signals to handleForward function.. buttonRow->addWidget(forwardButton); // Back Button - Steps one step backward. QPushButton *backButton = new QPushButton("BACK"); backButton->setFixedSize(100,25); connect(backButton, SIGNAL(clicked()), this, SLOT(handleBack())); // Signals to handleBack funciton. buttonRow->addWidget(backButton); // Start Button - Starts game when user clicks. Or, resumes game after being paused. QPushButton *startButton = new QPushButton("START/RESUME"); startButton->setFixedSize(100,25); connect(startButton, SIGNAL(clicked()), this, SLOT(handlePause())); // Deletes current timer if there is one. Then restarts everything. connect(startButton, SIGNAL(clicked()), this, SLOT(handleStart())); // Signals to handleStart function. buttonRow->addWidget(startButton); // Pause Button - Pauses simulation of game. QPushButton *pauseButton = new QPushButton("PAUSE"); pauseButton->setFixedSize(100,25); connect(pauseButton, SIGNAL(clicked()), this, SLOT(handlePause())); // Signals to pause function which pauses timer. buttonRow->addWidget(pauseButton); // Quit Button - Exits program. QPushButton *quitButton = new QPushButton("EXIT"); quitButton->setFixedSize(100,25); connect(quitButton, SIGNAL(clicked()), qApp, SLOT(quit())); // Signals the quit slot which ends the program. buttonRow->addWidget(quitButton); return buttonRow; // Returns bottom of layout. } /* SLOT method for handling clicks on the "clear" button. Receives "clicked" signals on the "Clear" button and sets all cells to DEAD. */ void GridWindow::handleClear() { for(unsigned int row=0; row < cells.size(); row++) // Loops through current rows' cells. { for(unsigned int col=0; col < cells[row].size(); col++) // Loops through the rows'columns' cells. { GridCell *cell = cells[row][col]; // Grab the current cell & set its value to dead. cell->setType(DEAD); } } } /* SLOT method for handling clicks on the "start" button. Receives "clicked" signals on the "start" button and begins game simulation. */ void GridWindow::handleStart() { isRunning = true; // It is running. Sets isRunning to true. this->timer = new QTimer(this); // Creates new timer. connect(this->timer, SIGNAL(timeout()), this, SLOT(timerFired())); // Connect "timerFired" method class to the "timeout" signal fired by the timer. this->timer->start(500); // Timer to fire every 500 milliseconds. } /* SLOT method for handling clicks on the "pause" button. Receives "clicked" signals on the "pause" button and stops the game simulation. */ void GridWindow::handlePause() { if(isRunning) // If it is running... this->timer->stop(); // Stops the timer. isRunning = false; // Set to false. } void GridWindow::handleForward() { if(isRunning); // If it's running, do nothing. else timerFired(); // It not running, step forward one step. } void GridWindow::handleBack() { std::vector<std::vector<GridCell*> > cells2; if(isRunning); // If it's running, do nothing. else if(backStack.empty()) cout << "EMPTYYY" << endl; else { cells2 = backStack.peek(); for (unsigned int f = 0; f < cells.size(); f++) // Loop through cells' rows. { for (unsigned int g = 0; g < cells.at(f).size(); g++) // Loop through cells columns. { cells[f][g]->setType(cells2[f][g]->getType()); // Set cells[f][g]'s type to cells2[f][g]'s type. } } cout << "PRE=POP" << endl; backStack.pop(); cout << "OYYYY" << endl; } } // Accessor method - Gets the 2D vector of grid cells. std::vector<std::vector<GridCell*> >& GridWindow::getCells() { return this->cells; } /* TimerFired function: 1) 2D-Vector cells2 is declared. 2) cells2 is initliazed with loops/push_backs so that all its cells are DEAD. 3) We loop through cells, and count the number of LIVE neighbors next to a given cell. --> Depending on how many cells are living, we choose if the cell should be LIVE or DEAD in the next simulation, according to the rules. -----> We save the cell type in cell2 at the same indice (the same row and column cell in cells2). 4) After check all the cells (and save the next round values in cells 2), we set cells's gridcells equal to cells2 gridcells. --> This causes the cells to be redrawn with cells2 types (white or black). */ void GridWindow::timerFired() { backStack.push(cells); std::vector<std::vector<GridCell*> > cells2; // Holds new values for 2D vector. These are the next simulation round of cell types. for(unsigned int i = 0; i < cells.size(); i++) // Loop through the rows of cells2. (Same size as cells' rows.) { vector<GridCell*> row; // Creates Gridcell* vector to push_back into cells2. cells2.push_back(row); // Pushes back row vectors into cells2. for(unsigned int j = 0; j < cells[i].size(); j++) // Loop through the columns (the cells in each row). { GridCell *cell = new GridCell(); // Creates new GridCell. cell->setType(DEAD); // Sets cell type to DEAD/white. cells2.at(i).push_back(cell); // Pushes back the DEAD cell into cells2. } // This makes a gridwindow the same size as cells with all DEAD cells. } for (unsigned int m = 0; m < cells.size(); m++) // Loop through cells' rows. { for (unsigned int n = 0; n < cells.at(m).size(); n++) // Loop through cells' columns. { unsigned int neighbors = 0; // Counter for number of LIVE neighbors for a given cell. // We know check all different variations of cells[i][j] to count the number of living neighbors for each cell. // We check m > 0 and/or n > 0 to make sure we don't access negative indexes (ex: cells[-1][0].) // We check m < size to make sure we don't try to access rows out of the vector (ex: row 5, if only 4 rows). // We check n < row size to make sure we don't access column item out of the vector (ex: 10th item in a column of only 9 items). // If we find that the Type = 1 (it is LIVE), then we add 1 to the neighbor. // Else - we add nothing to the neighbor counter. // Neighbor is the number of LIVE cells next to the current cell. if(m > 0 && n > 0) { if (cells[m-1][n-1]->getType() == 1) neighbors += 1; } if(m > 0) { if (cells[m-1][n]->getType() == 1) neighbors += 1; if(n < (cells.at(m).size() - 1)) { if (cells[m-1][n+1]->getType() == 1) neighbors += 1; } } if(n > 0) { if (cells[m][n-1]->getType() == 1) neighbors += 1; if(m < (cells.size() - 1)) { if (cells[m+1][n-1]->getType() == 1) neighbors += 1; } } if(n < (cells.at(m).size() - 1)) { if (cells[m][n+1]->getType() == 1) neighbors += 1; } if(m < (cells.size() - 1)) { if (cells[m+1][n]->getType() == 1) neighbors += 1; } if(m < (cells.size() - 1) && n < (cells.at(m).size() - 1)) { if (cells[m+1][n+1]->getType() == 1) neighbors += 1; } // Done checking number of neighbors for cells[m][n] // Now we change cells2 if it should switch in the next simulation step. // cells2 holds the values of what cells should be on the next iteration of the game. // We can't change cells right now, or it would through off our other cell values. // Apply game rules to cells: Create new, updated grid with the roundtwo vector. // Note - LIVE is 1; DEAD is 0. if (cells[m][n]->getType() == 1 && neighbors < 2) // If cell is LIVE and has less than 2 LIVE neighbors -> Set to DEAD. cells2[m][n]->setType(DEAD); else if (cells[m][n]->getType() == 1 && neighbors > 3) // If cell is LIVE and has more than 3 LIVE neighbors -> Set to DEAD. cells2[m][n]->setType(DEAD); else if (cells[m][n]->getType() == 1 && (neighbors == 2 || neighbors == 3)) // If cell is LIVE and has 2 or 3 LIVE neighbors -> Set to LIVE. cells2[m][n]->setType(LIVE); else if (cells[m][n]->getType() == 0 && neighbors == 3) // If cell is DEAD and has 3 LIVE neighbors -> Set to LIVE. cells2[m][n]->setType(LIVE); } } // Now we've gone through all of cells, and saved the new values in cells2. // Now we loop through cells and set all the cells' types to those of cells2. for (unsigned int f = 0; f < cells.size(); f++) // Loop through cells' rows. { for (unsigned int g = 0; g < cells.at(f).size(); g++) // Loop through cells columns. { cells[f][g]->setType(cells2[f][g]->getType()); // Set cells[f][g]'s type to cells2[f][g]'s type. } } } stack.h - Here's my stack. #ifndef STACK_H_ #define STACK_H_ #include <iostream> #include "node.h" template <typename T> class Stack { private: Node<T>* top; int listSize; public: Stack(); int size() const; bool empty() const; void push(const T& value); void pop(); T& peek() const; }; template <typename T> Stack<T>::Stack() : top(NULL) { listSize = 0; } template <typename T> int Stack<T>::size() const { return listSize; } template <typename T> bool Stack<T>::empty() const { if(listSize == 0) return true; else return false; } template <typename T> void Stack<T>::push(const T& value) { Node<T>* newOne = new Node<T>(value); newOne->next = top; top = newOne; listSize++; } template <typename T> void Stack<T>::pop() { Node<T>* oldT = top; top = top->next; delete oldT; listSize--; } template <typename T> T& Stack<T>::peek() const { return top->data; // Returns data in top item. } #endif gridcell.cpp - Gridcell implementation #include <iostream> #include "gridcell.h" using namespace std; // Constructor: Creates a grid cell. GridCell::GridCell(QWidget *parent) : QFrame(parent) { this->type = DEAD; // Default: Cell is DEAD (white). setFrameStyle(QFrame::Box); // Set the frame style. This is what gives each box its black border. this->button = new QPushButton(this); //Creates button that fills entirety of each grid cell. this->button->setSizePolicy(QSizePolicy::Expanding,QSizePolicy::Expanding); // Expands button to fill space. this->button->setMinimumSize(19,19); //width,height // Min height and width of button. QHBoxLayout *layout = new QHBoxLayout(); //Creates a simple layout to hold our button and add the button to it. layout->addWidget(this->button); setLayout(layout); layout->setStretchFactor(this->button,1); // Lets the buttons expand all the way to the edges of the current frame with no space leftover layout->setContentsMargins(0,0,0,0); layout->setSpacing(0); connect(this->button,SIGNAL(clicked()),this,SLOT(handleClick())); // Connects clicked signal with handleClick slot. redrawCell(); // Calls function to redraw (set new type for) the cell. } // Basic destructor. GridCell::~GridCell() { delete this->button; } // Accessor for the cell type. CellType GridCell::getType() const { return(this->type); } // Mutator for the cell type. Also has the side effect of causing the cell to be redrawn on the GUI. void GridCell::setType(CellType type) { this->type = type; redrawCell(); // Sets type and redraws cell. } // Handler slot for button clicks. This method is called whenever the user clicks on this cell in the grid. void GridCell::handleClick() { // When clicked on... if(this->type == DEAD) // If type is DEAD (white), change to LIVE (black). type = LIVE; else type = DEAD; // If type is LIVE (black), change to DEAD (white). setType(type); // Sets new type (color). setType Calls redrawCell() to recolor. } // Method to check cell type and return the color of that type. Qt::GlobalColor GridCell::getColorForCellType() { switch(this->type) { default: case DEAD: return Qt::white; case LIVE: return Qt::black; } } // Helper method. Forces current cell to be redrawn on the GUI. Called whenever the setType method is invoked. void GridCell::redrawCell() { Qt::GlobalColor gc = getColorForCellType(); //Find out what color this cell should be. this->button->setPalette(QPalette(gc,gc)); //Force the button in the cell to be the proper color. this->button->setAutoFillBackground(true); this->button->setFlat(true); //Force QT to NOT draw the borders on the button } Thanks a lot. Let me know if you need anything else.

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  • What are good design practices when working with Entity Framework

    - by AD
    This will apply mostly for an asp.net application where the data is not accessed via soa. Meaning that you get access to the objects loaded from the framework, not Transfer Objects, although some recommendation still apply. This is a community post, so please add to it as you see fit. Applies to: Entity Framework 1.0 shipped with Visual Studio 2008 sp1. Why pick EF in the first place? Considering it is a young technology with plenty of problems (see below), it may be a hard sell to get on the EF bandwagon for your project. However, it is the technology Microsoft is pushing (at the expense of Linq2Sql, which is a subset of EF). In addition, you may not be satisfied with NHibernate or other solutions out there. Whatever the reasons, there are people out there (including me) working with EF and life is not bad.make you think. EF and inheritance The first big subject is inheritance. EF does support mapping for inherited classes that are persisted in 2 ways: table per class and table the hierarchy. The modeling is easy and there are no programming issues with that part. (The following applies to table per class model as I don't have experience with table per hierarchy, which is, anyway, limited.) The real problem comes when you are trying to run queries that include one or many objects that are part of an inheritance tree: the generated sql is incredibly awful, takes a long time to get parsed by the EF and takes a long time to execute as well. This is a real show stopper. Enough that EF should probably not be used with inheritance or as little as possible. Here is an example of how bad it was. My EF model had ~30 classes, ~10 of which were part of an inheritance tree. On running a query to get one item from the Base class, something as simple as Base.Get(id), the generated SQL was over 50,000 characters. Then when you are trying to return some Associations, it degenerates even more, going as far as throwing SQL exceptions about not being able to query more than 256 tables at once. Ok, this is bad, EF concept is to allow you to create your object structure without (or with as little as possible) consideration on the actual database implementation of your table. It completely fails at this. So, recommendations? Avoid inheritance if you can, the performance will be so much better. Use it sparingly where you have to. In my opinion, this makes EF a glorified sql-generation tool for querying, but there are still advantages to using it. And ways to implement mechanism that are similar to inheritance. Bypassing inheritance with Interfaces First thing to know with trying to get some kind of inheritance going with EF is that you cannot assign a non-EF-modeled class a base class. Don't even try it, it will get overwritten by the modeler. So what to do? You can use interfaces to enforce that classes implement some functionality. For example here is a IEntity interface that allow you to define Associations between EF entities where you don't know at design time what the type of the entity would be. public enum EntityTypes{ Unknown = -1, Dog = 0, Cat } public interface IEntity { int EntityID { get; } string Name { get; } Type EntityType { get; } } public partial class Dog : IEntity { // implement EntityID and Name which could actually be fields // from your EF model Type EntityType{ get{ return EntityTypes.Dog; } } } Using this IEntity, you can then work with undefined associations in other classes // lets take a class that you defined in your model. // that class has a mapping to the columns: PetID, PetType public partial class Person { public IEntity GetPet() { return IEntityController.Get(PetID,PetType); } } which makes use of some extension functions: public class IEntityController { static public IEntity Get(int id, EntityTypes type) { switch (type) { case EntityTypes.Dog: return Dog.Get(id); case EntityTypes.Cat: return Cat.Get(id); default: throw new Exception("Invalid EntityType"); } } } Not as neat as having plain inheritance, particularly considering you have to store the PetType in an extra database field, but considering the performance gains, I would not look back. It also cannot model one-to-many, many-to-many relationship, but with creative uses of 'Union' it could be made to work. Finally, it creates the side effet of loading data in a property/function of the object, which you need to be careful about. Using a clear naming convention like GetXYZ() helps in that regards. Compiled Queries Entity Framework performance is not as good as direct database access with ADO (obviously) or Linq2SQL. There are ways to improve it however, one of which is compiling your queries. The performance of a compiled query is similar to Linq2Sql. What is a compiled query? It is simply a query for which you tell the framework to keep the parsed tree in memory so it doesn't need to be regenerated the next time you run it. So the next run, you will save the time it takes to parse the tree. Do not discount that as it is a very costly operation that gets even worse with more complex queries. There are 2 ways to compile a query: creating an ObjectQuery with EntitySQL and using CompiledQuery.Compile() function. (Note that by using an EntityDataSource in your page, you will in fact be using ObjectQuery with EntitySQL, so that gets compiled and cached). An aside here in case you don't know what EntitySQL is. It is a string-based way of writing queries against the EF. Here is an example: "select value dog from Entities.DogSet as dog where dog.ID = @ID". The syntax is pretty similar to SQL syntax. You can also do pretty complex object manipulation, which is well explained [here][1]. Ok, so here is how to do it using ObjectQuery< string query = "select value dog " + "from Entities.DogSet as dog " + "where dog.ID = @ID"; ObjectQuery<Dog> oQuery = new ObjectQuery<Dog>(query, EntityContext.Instance)); oQuery.Parameters.Add(new ObjectParameter("ID", id)); oQuery.EnablePlanCaching = true; return oQuery.FirstOrDefault(); The first time you run this query, the framework will generate the expression tree and keep it in memory. So the next time it gets executed, you will save on that costly step. In that example EnablePlanCaching = true, which is unnecessary since that is the default option. The other way to compile a query for later use is the CompiledQuery.Compile method. This uses a delegate: static readonly Func<Entities, int, Dog> query_GetDog = CompiledQuery.Compile<Entities, int, Dog>((ctx, id) => ctx.DogSet.FirstOrDefault(it => it.ID == id)); or using linq static readonly Func<Entities, int, Dog> query_GetDog = CompiledQuery.Compile<Entities, int, Dog>((ctx, id) => (from dog in ctx.DogSet where dog.ID == id select dog).FirstOrDefault()); to call the query: query_GetDog.Invoke( YourContext, id ); The advantage of CompiledQuery is that the syntax of your query is checked at compile time, where as EntitySQL is not. However, there are other consideration... Includes Lets say you want to have the data for the dog owner to be returned by the query to avoid making 2 calls to the database. Easy to do, right? EntitySQL string query = "select value dog " + "from Entities.DogSet as dog " + "where dog.ID = @ID"; ObjectQuery<Dog> oQuery = new ObjectQuery<Dog>(query, EntityContext.Instance)).Include("Owner"); oQuery.Parameters.Add(new ObjectParameter("ID", id)); oQuery.EnablePlanCaching = true; return oQuery.FirstOrDefault(); CompiledQuery static readonly Func<Entities, int, Dog> query_GetDog = CompiledQuery.Compile<Entities, int, Dog>((ctx, id) => (from dog in ctx.DogSet.Include("Owner") where dog.ID == id select dog).FirstOrDefault()); Now, what if you want to have the Include parametrized? What I mean is that you want to have a single Get() function that is called from different pages that care about different relationships for the dog. One cares about the Owner, another about his FavoriteFood, another about his FavotireToy and so on. Basicly, you want to tell the query which associations to load. It is easy to do with EntitySQL public Dog Get(int id, string include) { string query = "select value dog " + "from Entities.DogSet as dog " + "where dog.ID = @ID"; ObjectQuery<Dog> oQuery = new ObjectQuery<Dog>(query, EntityContext.Instance)) .IncludeMany(include); oQuery.Parameters.Add(new ObjectParameter("ID", id)); oQuery.EnablePlanCaching = true; return oQuery.FirstOrDefault(); } The include simply uses the passed string. Easy enough. Note that it is possible to improve on the Include(string) function (that accepts only a single path) with an IncludeMany(string) that will let you pass a string of comma-separated associations to load. Look further in the extension section for this function. If we try to do it with CompiledQuery however, we run into numerous problems: The obvious static readonly Func<Entities, int, string, Dog> query_GetDog = CompiledQuery.Compile<Entities, int, string, Dog>((ctx, id, include) => (from dog in ctx.DogSet.Include(include) where dog.ID == id select dog).FirstOrDefault()); will choke when called with: query_GetDog.Invoke( YourContext, id, "Owner,FavoriteFood" ); Because, as mentionned above, Include() only wants to see a single path in the string and here we are giving it 2: "Owner" and "FavoriteFood" (which is not to be confused with "Owner.FavoriteFood"!). Then, let's use IncludeMany(), which is an extension function static readonly Func<Entities, int, string, Dog> query_GetDog = CompiledQuery.Compile<Entities, int, string, Dog>((ctx, id, include) => (from dog in ctx.DogSet.IncludeMany(include) where dog.ID == id select dog).FirstOrDefault()); Wrong again, this time it is because the EF cannot parse IncludeMany because it is not part of the functions that is recognizes: it is an extension. Ok, so you want to pass an arbitrary number of paths to your function and Includes() only takes a single one. What to do? You could decide that you will never ever need more than, say 20 Includes, and pass each separated strings in a struct to CompiledQuery. But now the query looks like this: from dog in ctx.DogSet.Include(include1).Include(include2).Include(include3) .Include(include4).Include(include5).Include(include6) .[...].Include(include19).Include(include20) where dog.ID == id select dog which is awful as well. Ok, then, but wait a minute. Can't we return an ObjectQuery< with CompiledQuery? Then set the includes on that? Well, that what I would have thought so as well: static readonly Func<Entities, int, ObjectQuery<Dog>> query_GetDog = CompiledQuery.Compile<Entities, int, string, ObjectQuery<Dog>>((ctx, id) => (ObjectQuery<Dog>)(from dog in ctx.DogSet where dog.ID == id select dog)); public Dog GetDog( int id, string include ) { ObjectQuery<Dog> oQuery = query_GetDog(id); oQuery = oQuery.IncludeMany(include); return oQuery.FirstOrDefault; } That should have worked, except that when you call IncludeMany (or Include, Where, OrderBy...) you invalidate the cached compiled query because it is an entirely new one now! So, the expression tree needs to be reparsed and you get that performance hit again. So what is the solution? You simply cannot use CompiledQueries with parametrized Includes. Use EntitySQL instead. This doesn't mean that there aren't uses for CompiledQueries. It is great for localized queries that will always be called in the same context. Ideally CompiledQuery should always be used because the syntax is checked at compile time, but due to limitation, that's not possible. An example of use would be: you may want to have a page that queries which two dogs have the same favorite food, which is a bit narrow for a BusinessLayer function, so you put it in your page and know exactly what type of includes are required. Passing more than 3 parameters to a CompiledQuery Func is limited to 5 parameters, of which the last one is the return type and the first one is your Entities object from the model. So that leaves you with 3 parameters. A pitance, but it can be improved on very easily. public struct MyParams { public string param1; public int param2; public DateTime param3; } static readonly Func<Entities, MyParams, IEnumerable<Dog>> query_GetDog = CompiledQuery.Compile<Entities, MyParams, IEnumerable<Dog>>((ctx, myParams) => from dog in ctx.DogSet where dog.Age == myParams.param2 && dog.Name == myParams.param1 and dog.BirthDate > myParams.param3 select dog); public List<Dog> GetSomeDogs( int age, string Name, DateTime birthDate ) { MyParams myParams = new MyParams(); myParams.param1 = name; myParams.param2 = age; myParams.param3 = birthDate; return query_GetDog(YourContext,myParams).ToList(); } Return Types (this does not apply to EntitySQL queries as they aren't compiled at the same time during execution as the CompiledQuery method) Working with Linq, you usually don't force the execution of the query until the very last moment, in case some other functions downstream wants to change the query in some way: static readonly Func<Entities, int, string, IEnumerable<Dog>> query_GetDog = CompiledQuery.Compile<Entities, int, string, IEnumerable<Dog>>((ctx, age, name) => from dog in ctx.DogSet where dog.Age == age && dog.Name == name select dog); public IEnumerable<Dog> GetSomeDogs( int age, string name ) { return query_GetDog(YourContext,age,name); } public void DataBindStuff() { IEnumerable<Dog> dogs = GetSomeDogs(4,"Bud"); // but I want the dogs ordered by BirthDate gridView.DataSource = dogs.OrderBy( it => it.BirthDate ); } What is going to happen here? By still playing with the original ObjectQuery (that is the actual return type of the Linq statement, which implements IEnumerable), it will invalidate the compiled query and be force to re-parse. So, the rule of thumb is to return a List< of objects instead. static readonly Func<Entities, int, string, IEnumerable<Dog>> query_GetDog = CompiledQuery.Compile<Entities, int, string, IEnumerable<Dog>>((ctx, age, name) => from dog in ctx.DogSet where dog.Age == age && dog.Name == name select dog); public List<Dog> GetSomeDogs( int age, string name ) { return query_GetDog(YourContext,age,name).ToList(); //<== change here } public void DataBindStuff() { List<Dog> dogs = GetSomeDogs(4,"Bud"); // but I want the dogs ordered by BirthDate gridView.DataSource = dogs.OrderBy( it => it.BirthDate ); } When you call ToList(), the query gets executed as per the compiled query and then, later, the OrderBy is executed against the objects in memory. It may be a little bit slower, but I'm not even sure. One sure thing is that you have no worries about mis-handling the ObjectQuery and invalidating the compiled query plan. Once again, that is not a blanket statement. ToList() is a defensive programming trick, but if you have a valid reason not to use ToList(), go ahead. There are many cases in which you would want to refine the query before executing it. Performance What is the performance impact of compiling a query? It can actually be fairly large. A rule of thumb is that compiling and caching the query for reuse takes at least double the time of simply executing it without caching. For complex queries (read inherirante), I have seen upwards to 10 seconds. So, the first time a pre-compiled query gets called, you get a performance hit. After that first hit, performance is noticeably better than the same non-pre-compiled query. Practically the same as Linq2Sql When you load a page with pre-compiled queries the first time you will get a hit. It will load in maybe 5-15 seconds (obviously more than one pre-compiled queries will end up being called), while subsequent loads will take less than 300ms. Dramatic difference, and it is up to you to decide if it is ok for your first user to take a hit or you want a script to call your pages to force a compilation of the queries. Can this query be cached? { Dog dog = from dog in YourContext.DogSet where dog.ID == id select dog; } No, ad-hoc Linq queries are not cached and you will incur the cost of generating the tree every single time you call it. Parametrized Queries Most search capabilities involve heavily parametrized queries. There are even libraries available that will let you build a parametrized query out of lamba expressions. The problem is that you cannot use pre-compiled queries with those. One way around that is to map out all the possible criteria in the query and flag which one you want to use: public struct MyParams { public string name; public bool checkName; public int age; public bool checkAge; } static readonly Func<Entities, MyParams, IEnumerable<Dog>> query_GetDog = CompiledQuery.Compile<Entities, MyParams, IEnumerable<Dog>>((ctx, myParams) => from dog in ctx.DogSet where (myParams.checkAge == true && dog.Age == myParams.age) && (myParams.checkName == true && dog.Name == myParams.name ) select dog); protected List<Dog> GetSomeDogs() { MyParams myParams = new MyParams(); myParams.name = "Bud"; myParams.checkName = true; myParams.age = 0; myParams.checkAge = false; return query_GetDog(YourContext,myParams).ToList(); } The advantage here is that you get all the benifits of a pre-compiled quert. The disadvantages are that you most likely will end up with a where clause that is pretty difficult to maintain, that you will incur a bigger penalty for pre-compiling the query and that each query you run is not as efficient as it could be (particularly with joins thrown in). Another way is to build an EntitySQL query piece by piece, like we all did with SQL. protected List<Dod> GetSomeDogs( string name, int age) { string query = "select value dog from Entities.DogSet where 1 = 1 "; if( !String.IsNullOrEmpty(name) ) query = query + " and dog.Name == @Name "; if( age > 0 ) query = query + " and dog.Age == @Age "; ObjectQuery<Dog> oQuery = new ObjectQuery<Dog>( query, YourContext ); if( !String.IsNullOrEmpty(name) ) oQuery.Parameters.Add( new ObjectParameter( "Name", name ) ); if( age > 0 ) oQuery.Parameters.Add( new ObjectParameter( "Age", age ) ); return oQuery.ToList(); } Here the problems are: - there is no syntax checking during compilation - each different combination of parameters generate a different query which will need to be pre-compiled when it is first run. In this case, there are only 4 different possible queries (no params, age-only, name-only and both params), but you can see that there can be way more with a normal world search. - Noone likes to concatenate strings! Another option is to query a large subset of the data and then narrow it down in memory. This is particularly useful if you are working with a definite subset of the data, like all the dogs in a city. You know there are a lot but you also know there aren't that many... so your CityDog search page can load all the dogs for the city in memory, which is a single pre-compiled query and then refine the results protected List<Dod> GetSomeDogs( string name, int age, string city) { string query = "select value dog from Entities.DogSet where dog.Owner.Address.City == @City "; ObjectQuery<Dog> oQuery = new ObjectQuery<Dog>( query, YourContext ); oQuery.Parameters.Add( new ObjectParameter( "City", city ) ); List<Dog> dogs = oQuery.ToList(); if( !String.IsNullOrEmpty(name) ) dogs = dogs.Where( it => it.Name == name ); if( age > 0 ) dogs = dogs.Where( it => it.Age == age ); return dogs; } It is particularly useful when you start displaying all the data then allow for filtering. Problems: - Could lead to serious data transfer if you are not careful about your subset. - You can only filter on the data that you returned. It means that if you don't return the Dog.Owner association, you will not be able to filter on the Dog.Owner.Name So what is the best solution? There isn't any. You need to pick the solution that works best for you and your problem: - Use lambda-based query building when you don't care about pre-compiling your queries. - Use fully-defined pre-compiled Linq query when your object structure is not too complex. - Use EntitySQL/string concatenation when the structure could be complex and when the possible number of different resulting queries are small (which means fewer pre-compilation hits). - Use in-memory filtering when you are working with a smallish subset of the data or when you had to fetch all of the data on the data at first anyway (if the performance is fine with all the data, then filtering in memory will not cause any time to be spent in the db). Singleton access The best way to deal with your context and entities accross all your pages is to use the singleton pattern: public sealed class YourContext { private const string instanceKey = "On3GoModelKey"; YourContext(){} public static YourEntities Instance { get { HttpContext context = HttpContext.Current; if( context == null ) return Nested.instance; if (context.Items[instanceKey] == null) { On3GoEntities entity = new On3GoEntities(); context.Items[instanceKey] = entity; } return (YourEntities)context.Items[instanceKey]; } } class Nested { // Explicit static constructor to tell C# compiler // not to mark type as beforefieldinit static Nested() { } internal static readonly YourEntities instance = new YourEntities(); } } NoTracking, is it worth it? When executing a query, you can tell the framework to track the objects it will return or not. What does it mean? With tracking enabled (the default option), the framework will track what is going on with the object (has it been modified? Created? Deleted?) and will also link objects together, when further queries are made from the database, which is what is of interest here. For example, lets assume that Dog with ID == 2 has an owner which ID == 10. Dog dog = (from dog in YourContext.DogSet where dog.ID == 2 select dog).FirstOrDefault(); //dog.OwnerReference.IsLoaded == false; Person owner = (from o in YourContext.PersonSet where o.ID == 10 select dog).FirstOrDefault(); //dog.OwnerReference.IsLoaded == true; If we were to do the same with no tracking, the result would be different. ObjectQuery<Dog> oDogQuery = (ObjectQuery<Dog>) (from dog in YourContext.DogSet where dog.ID == 2 select dog); oDogQuery.MergeOption = MergeOption.NoTracking; Dog dog = oDogQuery.FirstOrDefault(); //dog.OwnerReference.IsLoaded == false; ObjectQuery<Person> oPersonQuery = (ObjectQuery<Person>) (from o in YourContext.PersonSet where o.ID == 10 select o); oPersonQuery.MergeOption = MergeOption.NoTracking; Owner owner = oPersonQuery.FirstOrDefault(); //dog.OwnerReference.IsLoaded == false; Tracking is very useful and in a perfect world without performance issue, it would always be on. But in this world, there is a price for it, in terms of performance. So, should you use NoTracking to speed things up? It depends on what you are planning to use the data for. Is there any chance that the data your query with NoTracking can be used to make update/insert/delete in the database? If so, don't use NoTracking because associations are not tracked and will causes exceptions to be thrown. In a page where there are absolutly no updates to the database, you can use NoTracking. Mixing tracking and NoTracking is possible, but it requires you to be extra careful with updates/inserts/deletes. The problem is that if you mix then you risk having the framework trying to Attach() a NoTracking object to the context where another copy of the same object exist with tracking on. Basicly, what I am saying is that Dog dog1 = (from dog in YourContext.DogSet where dog.ID == 2).FirstOrDefault(); ObjectQuery<Dog> oDogQuery = (ObjectQuery<Dog>) (from dog in YourContext.DogSet where dog.ID == 2 select dog); oDogQuery.MergeOption = MergeOption.NoTracking; Dog dog2 = oDogQuery.FirstOrDefault(); dog1 and dog2 are 2 different objects, one tracked and one not. Using the detached object in an update/insert will force an Attach() that will say "Wait a minute, I do already have an object here with the same database key. Fail". And when you Attach() one object, all of its hierarchy gets attached as well, causing problems everywhere. Be extra careful. How much faster is it with NoTracking It depends on the queries. Some are much more succeptible to tracking than other. I don't have a fast an easy rule for it, but it helps. So I should use NoTracking everywhere then? Not exactly. There are some advantages to tracking object. The first one is that the object is cached, so subsequent call for that object will not hit the database. That cache is only valid for the lifetime of the YourEntities object, which, if you use the singleton code above, is the same as the page lifetime. One page request == one YourEntity object. So for multiple calls for the same object, it will load only once per page request. (Other caching mechanism could extend that). What happens when you are using NoTracking and try to load the same object multiple times? The database will be queried each time, so there is an impact there. How often do/should you call for the same object during a single page request? As little as possible of course, but it does happens. Also remember the piece above about having the associations connected automatically for your? You don't have that with NoTracking, so if you load your data in multiple batches, you will not have a link to between them: ObjectQuery<Dog> oDogQuery = (ObjectQuery<Dog>)(from dog in YourContext.DogSet select dog); oDogQuery.MergeOption = MergeOption.NoTracking; List<Dog> dogs = oDogQuery.ToList(); ObjectQuery<Person> oPersonQuery = (ObjectQuery<Person>)(from o in YourContext.PersonSet select o); oPersonQuery.MergeOption = MergeOption.NoTracking; List<Person> owners = oPersonQuery.ToList(); In this case, no dog will have its .Owner property set. Some things to keep in mind when you are trying to optimize the performance. No lazy loading, what am I to do? This can be seen as a blessing in disguise. Of course it is annoying to load everything manually. However, it decreases the number of calls to the db and forces you to think about when you should load data. The more you can load in one database call the better. That was always true, but it is enforced now with this 'feature' of EF. Of course, you can call if( !ObjectReference.IsLoaded ) ObjectReference.Load(); if you want to, but a better practice is to force the framework to load the objects you know you will need in one shot. This is where the discussion about parametrized Includes begins to make sense. Lets say you have you Dog object public class Dog { public Dog Get(int id) { return YourContext.DogSet.FirstOrDefault(it => it.ID == id ); } } This is the type of function you work with all the time. It gets called from all over the place and once you have that Dog object, you will do very different things to it in different functions. First, it should be pre-compiled, because you will call that very often. Second, each different pages will want to have access to a different subset of the Dog data. Some will want the Owner, some the FavoriteToy, etc. Of course, you could call Load() for each reference you need anytime you need one. But that will generate a call to the database each time. Bad idea. So instead, each page will ask for the data it wants to see when it first request for the Dog object: static public Dog Get(int id) { return GetDog(entity,"");} static public Dog Get(int id, string includePath) { string query = "select value o " + " from YourEntities.DogSet as o " +

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