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  • LINQ: Single vs. First

    - by Paulo Morgado
    I’ve witnessed and been involved in several discussions around the correctness or usefulness of the Single method in the LINQ API. The most common argument is that you are querying for the first element on the result set and an exception will be thrown if there’s more than one element. The First method should be used instead, because it doesn’t throw if the result set has more than one item. Although the documentation for Single states that it returns a single, specific element of a sequence of values, it actually returns THE single, specific element of a sequence of ONE value. One you use the Single method in your code you are asserting that your query will result in a scalar result instead of a result set of arbitrary length. On the other hand, the documentation for First states that it returns the first element of a sequence of arbitrary length. Imagine you want to catch a taxi. You go the the taxi line and catch the FIRST one, no matter how many are there. On the other hand, if you go the the parking lot to get your car, you want the SINGLE one specific car that’s yours. If your “query” “returns” more than one car, it’s an exception. Either because it “returned” not only your car or you happen to have more than one car in that parking lot. In either case, you can only drive one car at once and you’ll need to refine your “query”.

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  • How to Switch Chrome’s Default Search to International Google

    - by Erez Zukerman
    Google Chrome’s default search engine is Google. This makes perfect sense; the only problem is that it uses localized Google – for example, Google France or Google Israel. This impacts the interface language, and sometimes even the text orientation. Here’s how you can fix this and get “international” Google results with an English interface. First, we need to figure out what search query we’re going to use. Go to Google.com and execute a simple query for a single word – say “cats”. If you get real-time results, hit Enter so that the address bar updates with the query URL. It should look something like this: http://www.google.com/#sclient=psy&hl=en&site=&source=hp&q=cats&aq=f&aqi=g1g-s1g3&aql=&oq=&pbx=1&bav=on.2,or.&fp=369c8973645261b8 If you wish to customize your search further, click Advanced Search. For example, I would like Google to annotate results with the reading level they require, so I can see what’s going to be difficult to read: Latest Features How-To Geek ETC Macs Don’t Make You Creative! So Why Do Artists Really Love Apple? MacX DVD Ripper Pro is Free for How-To Geek Readers (Time Limited!) HTG Explains: What’s a Solid State Drive and What Do I Need to Know? How to Get Amazing Color from Photos in Photoshop, GIMP, and Paint.NET Learn To Adjust Contrast Like a Pro in Photoshop, GIMP, and Paint.NET Have You Ever Wondered How Your Operating System Got Its Name? Lakeside Sunset in the Mountains [Wallpaper] Taskbar Meters Turn Your Taskbar into a System Resource Monitor Create Shortcuts for Your Favorite or Most Used Folders in Ubuntu Create Custom Sized Thumbnail Images with Simple Image Resizer [Cross-Platform] Etch a Circuit Board using a Simple Homemade Mixture Sync Blocker Stops iTunes from Automatically Syncing

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  • Is it bad to have an "Obsessive Refactoring Disorder"?

    - by Rachel
    I was reading this question and realized that could almost be me. I am fairly OCD about refactoring someone else's code when I see that I can improve it. For example, if the code contains duplicate methods to do the same thing with nothing more than a single parameter changing, I feel I have to remove all the copy/paste methods and replace it with one generic one. Is this bad? Should I try and stop? I try not to refactor unless I can actually make improvements to the code performance or readability, or if the person who did the code isn't following our standard naming conventions (I hate expecting a variable to be local because of the naming standard, only to discover it is a global variable which has been incorrectly named)

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  • ASP.NET MVC 3 Hosting :: ASP.NET MVC 3 First Look

    - by mbridge
    MVC 3 View Enhancements MVC 3 introduces two improvements to the MVC view engine: - Ability to select the view engine to use. MVC 3 allows you to select from any of your  installed view engines from Visual Studio by selecting Add > View (including the newly introduced ASP.NET “Razor” engine”): - Support for the next ASP.NET “Razor” syntax. The newly previewed Razor syntax is a concise lightweight syntax. MVC 3 Control Enhancements - Global Filters: ASP.NET MVC 3  allows you to specify that a filter which applies globally to all Controllers within an app by adding it to the GlobalFilters collection.  The RegisterGlobalFilters() method is now included in the default Global.asax class template and so provides a convenient place to do this since is will then be called by the Application_Start() method: void RegisterGlobalFilters(GlobalFilterCollection filters) { filters.Add(new HandleLoggingAttribute()); filters.Add(new HandleErrorAttribute()); } void Application_Start() { RegisterGlobalFilters (GlobalFilters.Filters); } - Dynamic ViewModel Property : MVC 3 augments the ViewData API with a new “ViewModel” property on Controller which is of type “dynamic” – and therefore enables you to use the new dynamic language support in C# and VB pass ViewData items using a cleaner syntax than the current dictionary API. Public ActionResult Index() { ViewModel.Message = "Hello World"; return View(); } - New ActionResult Types : MVC 3 includes three new ActionResult types and helper methods: 1. HttpNotFoundResult – indicates that a resource which was requested by the current URL was not found. HttpNotFoundResult will return a 404 HTTP status code to the calling client. 2. PermanentRedirects – The HttpRedirectResult class contains a new Boolean “Permanent” property which is used to indicate that a permanent redirect should be done. Permanent redirects use a HTTP 301 status code.  The Controller class  includes three new methods for performing these permanent redirects: RedirectPermanent(), RedirectToRoutePermanent(), andRedirectToActionPermanent(). All  of these methods will return an instance of the HttpRedirectResult object with the Permanent property set to true. 3. HttpStatusCodeResult – used for setting an explicit response status code and its associated description. MVC 3 AJAX and JavaScript Enhancements MVC 3 ships with built-in JSON binding support which enables action methods to receive JSON-encoded data and then model-bind it to action method parameters. For example a jQuery client-side JavaScript could define a “save” event handler which will be invoked when the save button is clicked on the client. The code in the event handler then constructs a client-side JavaScript “product” object with 3 fields with their values retrieved from HTML input elements. Finally, it uses jQuery’s .ajax() method to POST a JSON based request which contains the product to a /theStore/UpdateProduct URL on the server: $('#save').click(function () { var product = { ProdName: $('#Name').val() Price: $('#Price').val(), } $.ajax({ url: '/theStore/UpdateProduct', type: "POST"; data: JSON.stringify(widget), datatype: "json", contentType: "application/json; charset=utf-8", success: function () { $('#message').html('Saved').fadeIn(), }, error: function () { $('#message').html('Error').fadeIn(), } }); return false; }); MVC will allow you to implement the /theStore/UpdateProduct URL on the server by using an action method as below. The UpdateProduct() action method will accept a strongly-typed Product object for a parameter. MVC 3 can now automatically bind an incoming JSON post value to the .NET Product type on the server without having to write any custom binding. [HttpPost] public ActionResult UpdateProduct(Product product) { // save logic here return null } MVC 3 Model Validation Enhancements MVC 3 builds on the MVC 2 model validation improvements by adding   support for several of the new validation features within the System.ComponentModel.DataAnnotations namespace in .NET 4.0: - Support for the new DataAnnotations metadata attributes like DisplayAttribute. - Support for the improvements made to the ValidationAttribute class which now supports a new IsValid overload that provides more info on  the current validation context, like what object is being validated. - Support for the new IValidatableObject interface which enables you to perform model-level validation and also provide validation error messages which are specific to the state of the overall model. MVC 3 Dependency Injection Enhancements MVC 3 includes better support for applying Dependency Injection (DI) and also integrating with Dependency Injection/IOC containers. Currently MVC 3 Preview 1 has support for DI in the below places: - Controllers (registering & injecting controller factories and injecting controllers) - Views (registering & injecting view engines, also for injecting dependencies into view pages) - Action Filters (locating and  injecting filters) And this is another important blog about Microsoft .NET and technology: - Windows 2008 Blog - SharePoint 2010 Blog - .NET 4 Blog And you can visit here if you're looking for ASP.NET MVC 3 hosting

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  • XNA Screen Manager problem with transitions

    - by NexAddo
    I'm having issues using the game statemanagement example in the game I am developing. I have no issues with my first three screens transitioning between one another. I have a main menu screen, a splash screen and a high score screen that cycle: mainMenuScreen->splashScreen->highScoreScreen->mainMenuScreen The screens change every 15 seconds. Transition times public MainMenuScreen() { TransitionOnTime = TimeSpan.FromSeconds(0.5); TransitionOffTime = TimeSpan.FromSeconds(0.0); currentCreditAmount = Global.CurrentCredits; } public SplashScreen() { TransitionOnTime = TimeSpan.FromSeconds(0.5); TransitionOffTime = TimeSpan.FromSeconds(0.5); } public HighScoreScreen() { TransitionOnTime = TimeSpan.FromSeconds(0.5); TransitionOffTime = TimeSpan.FromSeconds(0.5); } public GamePlayScreen() { TransitionOnTime = TimeSpan.FromSeconds(0.5); TransitionOffTime = TimeSpan.FromSeconds(0.5); } When a user inserts credits they can play the game after pressing start mainMenuScreen->splashScreen->highScoreScreen->(loops forever) || || || ===========Credits In============= || Start || \/ LoadingScreen || Start || \/ GamePlayScreen During each of these transitions, between screens, the same code is used, which exits(removes) all current active screens and respects transitions, then adds the new screen to the screen manager: foreach (GameScreen screen in ScreenManager.GetScreens()) screen.ExitScreen(); //AddScreen takes a new screen to manage and the controlling player ScreenManager.AddScreen(new NameOfScreenHere(), null); Each screen is removed from the ScreenManager with ExitScreen() and using this function, each screen transition is respected. The problem I am having is with my gamePlayScreen. When the current game is finished and the transition is complete for the gamePlayScreen, it should be removed and the next screens should be added to the ScreenManager. GamePlayScreen Code Snippet private void FinishCurrentGame() { AudioManager.StopSounds(); this.UnloadContent(); if (Global.SaveDevice.IsReady) Stats.Save(); if (HighScoreScreen.IsInHighscores(timeLimit)) { foreach (GameScreen screen in ScreenManager.GetScreens()) screen.ExitScreen(); Global.TimeRemaining = timeLimit; ScreenManager.AddScreen(new BackgroundScreen(), null); ScreenManager.AddScreen(new MessageBoxScreen("Enter your Initials", true), null); } else { foreach (GameScreen screen in ScreenManager.GetScreens()) screen.ExitScreen(); ScreenManager.AddScreen(new BackgroundScreen(), null); ScreenManager.AddScreen(new MainMenuScreen(), null); } } The problem is that when isExiting is set to true by screen.ExitScreen() for the gamePlayScreen, the transition never completes the transition and removes the screen from the ScreenManager. Every other screen that I use the same technique to add and remove each screen fully transitions On/Off and is removed at the appropriate time from the ScreenManager, but noy my GamePlayScreen. Has anyone that has used the GameStateManagement example experienced this issue or can someone see the mistake I am making? EDIT This is what I tracked down. When the game is done, I call foreach (GameScreen screen in ScreenManager.GetScreens()) screen.ExitScreen(); to start the transition off process for the gameplay screen. At this point there is only 1 screen on the ScreenManager stack. The gamePlay screen gets isExiting set to true and starts to transition off. Right after the above call to ExitScreen() I add a background screen and menu screen to the screenManager: ScreenManager.AddScreen(new background(), null); ScreenManager.AddScreen(new Menu(), null); The count of the ScreenManager is now 3. What I noticed while stepping through the updates for GameScreen and ScreenManager, the gameplay screen never gets to the point where the transistion process finishes so the ScreenManager can remove it from the stack. This anomaly does not happen to any of my other screens when I switch between them. Screen Manager Code #region File Description //----------------------------------------------------------------------------- // ScreenManager.cs // // Microsoft XNA Community Game Platform // Copyright (C) Microsoft Corporation. All rights reserved. //----------------------------------------------------------------------------- #endregion #define DEMO #region Using Statements using System; using System.Diagnostics; using System.Collections.Generic; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Content; using Microsoft.Xna.Framework.Graphics; using PerformanceUtility.GameDebugTools; #endregion namespace GameStateManagement { /// <summary> /// The screen manager is a component which manages one or more GameScreen /// instances. It maintains a stack of screens, calls their Update and Draw /// methods at the appropriate times, and automatically routes input to the /// topmost active screen. /// </summary> public class ScreenManager : DrawableGameComponent { #region Fields List<GameScreen> screens = new List<GameScreen>(); List<GameScreen> screensToUpdate = new List<GameScreen>(); InputState input = new InputState(); SpriteBatch spriteBatch; SpriteFont font; Texture2D blankTexture; bool isInitialized; bool getOut; bool traceEnabled; #if DEBUG DebugSystem debugSystem; Stopwatch stopwatch = new Stopwatch(); bool debugTextEnabled; #endif #endregion #region Properties /// <summary> /// A default SpriteBatch shared by all the screens. This saves /// each screen having to bother creating their own local instance. /// </summary> public SpriteBatch SpriteBatch { get { return spriteBatch; } } /// <summary> /// A default font shared by all the screens. This saves /// each screen having to bother loading their own local copy. /// </summary> public SpriteFont Font { get { return font; } } public Rectangle ScreenRectangle { get { return new Rectangle(0, 0, GraphicsDevice.Viewport.Width, GraphicsDevice.Viewport.Height); } } /// <summary> /// If true, the manager prints out a list of all the screens /// each time it is updated. This can be useful for making sure /// everything is being added and removed at the right times. /// </summary> public bool TraceEnabled { get { return traceEnabled; } set { traceEnabled = value; } } #if DEBUG public bool DebugTextEnabled { get { return debugTextEnabled; } set { debugTextEnabled = value; } } public DebugSystem DebugSystem { get { return debugSystem; } } #endif #endregion #region Initialization /// <summary> /// Constructs a new screen manager component. /// </summary> public ScreenManager(Game game) : base(game) { // we must set EnabledGestures before we can query for them, but // we don't assume the game wants to read them. //TouchPanel.EnabledGestures = GestureType.None; } /// <summary> /// Initializes the screen manager component. /// </summary> public override void Initialize() { base.Initialize(); #if DEBUG debugSystem = DebugSystem.Initialize(Game, "Fonts/MenuFont"); #endif isInitialized = true; } /// <summary> /// Load your graphics content. /// </summary> protected override void LoadContent() { // Load content belonging to the screen manager. ContentManager content = Game.Content; spriteBatch = new SpriteBatch(GraphicsDevice); font = content.Load<SpriteFont>(@"Fonts\menufont"); blankTexture = content.Load<Texture2D>(@"Textures\Backgrounds\blank"); // Tell each of the screens to load their content. foreach (GameScreen screen in screens) { screen.LoadContent(); } } /// <summary> /// Unload your graphics content. /// </summary> protected override void UnloadContent() { // Tell each of the screens to unload their content. foreach (GameScreen screen in screens) { screen.UnloadContent(); } } #endregion #region Update and Draw /// <summary> /// Allows each screen to run logic. /// </summary> public override void Update(GameTime gameTime) { #if DEBUG debugSystem.TimeRuler.StartFrame(); debugSystem.TimeRuler.BeginMark("Update", Color.Blue); if (debugTextEnabled && getOut == false) { debugSystem.FpsCounter.Visible = true; debugSystem.TimeRuler.Visible = true; debugSystem.TimeRuler.ShowLog = true; getOut = true; } else if (debugTextEnabled == false) { getOut = false; debugSystem.FpsCounter.Visible = false; debugSystem.TimeRuler.Visible = false; debugSystem.TimeRuler.ShowLog = false; } #endif // Read the keyboard and gamepad. input.Update(); // Make a copy of the master screen list, to avoid confusion if // the process of updating one screen adds or removes others. screensToUpdate.Clear(); foreach (GameScreen screen in screens) screensToUpdate.Add(screen); bool otherScreenHasFocus = !Game.IsActive; bool coveredByOtherScreen = false; // Loop as long as there are screens waiting to be updated. while (screensToUpdate.Count > 0) { // Pop the topmost screen off the waiting list. GameScreen screen = screensToUpdate[screensToUpdate.Count - 1]; screensToUpdate.RemoveAt(screensToUpdate.Count - 1); // Update the screen. screen.Update(gameTime, otherScreenHasFocus, coveredByOtherScreen); if (screen.ScreenState == ScreenState.TransitionOn || screen.ScreenState == ScreenState.Active) { // If this is the first active screen we came across, // give it a chance to handle input. if (!otherScreenHasFocus) { screen.HandleInput(input); otherScreenHasFocus = true; } // If this is an active non-popup, inform any subsequent // screens that they are covered by it. if (!screen.IsPopup) coveredByOtherScreen = true; } } // Print debug trace? if (traceEnabled) TraceScreens(); #if DEBUG debugSystem.TimeRuler.EndMark("Update"); #endif } /// <summary> /// Prints a list of all the screens, for debugging. /// </summary> void TraceScreens() { List<string> screenNames = new List<string>(); foreach (GameScreen screen in screens) screenNames.Add(screen.GetType().Name); Debug.WriteLine(string.Join(", ", screenNames.ToArray())); } /// <summary> /// Tells each screen to draw itself. /// </summary> public override void Draw(GameTime gameTime) { #if DEBUG debugSystem.TimeRuler.StartFrame(); debugSystem.TimeRuler.BeginMark("Draw", Color.Yellow); #endif foreach (GameScreen screen in screens) { if (screen.ScreenState == ScreenState.Hidden) continue; screen.Draw(gameTime); } #if DEBUG debugSystem.TimeRuler.EndMark("Draw"); #endif #if DEMO SpriteBatch.Begin(); SpriteBatch.DrawString(font, "DEMO - NOT FOR RESALE", new Vector2(20, 80), Color.White); SpriteBatch.End(); #endif } #endregion #region Public Methods /// <summary> /// Adds a new screen to the screen manager. /// </summary> public void AddScreen(GameScreen screen, PlayerIndex? controllingPlayer) { screen.ControllingPlayer = controllingPlayer; screen.ScreenManager = this; screen.IsExiting = false; // If we have a graphics device, tell the screen to load content. if (isInitialized) { screen.LoadContent(); } screens.Add(screen); } /// <summary> /// Removes a screen from the screen manager. You should normally /// use GameScreen.ExitScreen instead of calling this directly, so /// the screen can gradually transition off rather than just being /// instantly removed. /// </summary> public void RemoveScreen(GameScreen screen) { // If we have a graphics device, tell the screen to unload content. if (isInitialized) { screen.UnloadContent(); } screens.Remove(screen); screensToUpdate.Remove(screen); } /// <summary> /// Expose an array holding all the screens. We return a copy rather /// than the real master list, because screens should only ever be added /// or removed using the AddScreen and RemoveScreen methods. /// </summary> public GameScreen[] GetScreens() { return screens.ToArray(); } /// <summary> /// Helper draws a translucent black fullscreen sprite, used for fading /// screens in and out, and for darkening the background behind popups. /// </summary> public void FadeBackBufferToBlack(float alpha) { Viewport viewport = GraphicsDevice.Viewport; spriteBatch.Begin(); spriteBatch.Draw(blankTexture, new Rectangle(0, 0, viewport.Width, viewport.Height), Color.Black * alpha); spriteBatch.End(); } #endregion } } Game Screen Parent of GamePlayScreen #region File Description //----------------------------------------------------------------------------- // GameScreen.cs // // Microsoft XNA Community Game Platform // Copyright (C) Microsoft Corporation. All rights reserved. //----------------------------------------------------------------------------- #endregion #region Using Statements using System; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Input; //using Microsoft.Xna.Framework.Input.Touch; using System.IO; #endregion namespace GameStateManagement { /// <summary> /// Enum describes the screen transition state. /// </summary> public enum ScreenState { TransitionOn, Active, TransitionOff, Hidden, } /// <summary> /// A screen is a single layer that has update and draw logic, and which /// can be combined with other layers to build up a complex menu system. /// For instance the main menu, the options menu, the "are you sure you /// want to quit" message box, and the main game itself are all implemented /// as screens. /// </summary> public abstract class GameScreen { #region Properties /// <summary> /// Normally when one screen is brought up over the top of another, /// the first screen will transition off to make room for the new /// one. This property indicates whether the screen is only a small /// popup, in which case screens underneath it do not need to bother /// transitioning off. /// </summary> public bool IsPopup { get { return isPopup; } protected set { isPopup = value; } } bool isPopup = false; /// <summary> /// Indicates how long the screen takes to /// transition on when it is activated. /// </summary> public TimeSpan TransitionOnTime { get { return transitionOnTime; } protected set { transitionOnTime = value; } } TimeSpan transitionOnTime = TimeSpan.Zero; /// <summary> /// Indicates how long the screen takes to /// transition off when it is deactivated. /// </summary> public TimeSpan TransitionOffTime { get { return transitionOffTime; } protected set { transitionOffTime = value; } } TimeSpan transitionOffTime = TimeSpan.Zero; /// <summary> /// Gets the current position of the screen transition, ranging /// from zero (fully active, no transition) to one (transitioned /// fully off to nothing). /// </summary> public float TransitionPosition { get { return transitionPosition; } protected set { transitionPosition = value; } } float transitionPosition = 1; /// <summary> /// Gets the current alpha of the screen transition, ranging /// from 1 (fully active, no transition) to 0 (transitioned /// fully off to nothing). /// </summary> public float TransitionAlpha { get { return 1f - TransitionPosition; } } /// <summary> /// Gets the current screen transition state. /// </summary> public ScreenState ScreenState { get { return screenState; } protected set { screenState = value; } } ScreenState screenState = ScreenState.TransitionOn; /// <summary> /// There are two possible reasons why a screen might be transitioning /// off. It could be temporarily going away to make room for another /// screen that is on top of it, or it could be going away for good. /// This property indicates whether the screen is exiting for real: /// if set, the screen will automatically remove itself as soon as the /// transition finishes. /// </summary> public bool IsExiting { get { return isExiting; } protected internal set { isExiting = value; } } bool isExiting = false; /// <summary> /// Checks whether this screen is active and can respond to user input. /// </summary> public bool IsActive { get { return !otherScreenHasFocus && (screenState == ScreenState.TransitionOn || screenState == ScreenState.Active); } } bool otherScreenHasFocus; /// <summary> /// Gets the manager that this screen belongs to. /// </summary> public ScreenManager ScreenManager { get { return screenManager; } internal set { screenManager = value; } } ScreenManager screenManager; public KeyboardState KeyboardState { get {return Keyboard.GetState();} } /// <summary> /// Gets the index of the player who is currently controlling this screen, /// or null if it is accepting input from any player. This is used to lock /// the game to a specific player profile. The main menu responds to input /// from any connected gamepad, but whichever player makes a selection from /// this menu is given control over all subsequent screens, so other gamepads /// are inactive until the controlling player returns to the main menu. /// </summary> public PlayerIndex? ControllingPlayer { get { return controllingPlayer; } internal set { controllingPlayer = value; } } PlayerIndex? controllingPlayer; /// <summary> /// Gets whether or not this screen is serializable. If this is true, /// the screen will be recorded into the screen manager's state and /// its Serialize and Deserialize methods will be called as appropriate. /// If this is false, the screen will be ignored during serialization. /// By default, all screens are assumed to be serializable. /// </summary> public bool IsSerializable { get { return isSerializable; } protected set { isSerializable = value; } } bool isSerializable = true; #endregion #region Initialization /// <summary> /// Load graphics content for the screen. /// </summary> public virtual void LoadContent() { } /// <summary> /// Unload content for the screen. /// </summary> public virtual void UnloadContent() { } #endregion #region Update and Draw /// <summary> /// Allows the screen to run logic, such as updating the transition position. /// Unlike HandleInput, this method is called regardless of whether the screen /// is active, hidden, or in the middle of a transition. /// </summary> public virtual void Update(GameTime gameTime, bool otherScreenHasFocus, bool coveredByOtherScreen) { this.otherScreenHasFocus = otherScreenHasFocus; if (isExiting) { // If the screen is going away to die, it should transition off. screenState = ScreenState.TransitionOff; if (!UpdateTransition(gameTime, transitionOffTime, 1)) { // When the transition finishes, remove the screen. ScreenManager.RemoveScreen(this); } } else if (coveredByOtherScreen) { // If the screen is covered by another, it should transition off. if (UpdateTransition(gameTime, transitionOffTime, 1)) { // Still busy transitioning. screenState = ScreenState.TransitionOff; } else { // Transition finished! screenState = ScreenState.Hidden; } } else { // Otherwise the screen should transition on and become active. if (UpdateTransition(gameTime, transitionOnTime, -1)) { // Still busy transitioning. screenState = ScreenState.TransitionOn; } else { // Transition finished! screenState = ScreenState.Active; } } } /// <summary> /// Helper for updating the screen transition position. /// </summary> bool UpdateTransition(GameTime gameTime, TimeSpan time, int direction) { // How much should we move by? float transitionDelta; if (time == TimeSpan.Zero) transitionDelta = 1; else transitionDelta = (float)(gameTime.ElapsedGameTime.TotalMilliseconds / time.TotalMilliseconds); // Update the transition position. transitionPosition += transitionDelta * direction; // Did we reach the end of the transition? if (((direction < 0) && (transitionPosition <= 0)) || ((direction > 0) && (transitionPosition >= 1))) { transitionPosition = MathHelper.Clamp(transitionPosition, 0, 1); return false; } // Otherwise we are still busy transitioning. return true; } /// <summary> /// Allows the screen to handle user input. Unlike Update, this method /// is only called when the screen is active, and not when some other /// screen has taken the focus. /// </summary> public virtual void HandleInput(InputState input) { } public KeyboardState currentKeyState; public KeyboardState lastKeyState; public bool IsKeyHit(Keys key) { if (currentKeyState.IsKeyDown(key) && lastKeyState.IsKeyUp(key)) return true; return false; } /// <summary> /// This is called when the screen should draw itself. /// </summary> public virtual void Draw(GameTime gameTime) { } #endregion #region Public Methods /// <summary> /// Tells the screen to serialize its state into the given stream. /// </summary> public virtual void Serialize(Stream stream) { } /// <summary> /// Tells the screen to deserialize its state from the given stream. /// </summary> public virtual void Deserialize(Stream stream) { } /// <summary> /// Tells the screen to go away. Unlike ScreenManager.RemoveScreen, which /// instantly kills the screen, this method respects the transition timings /// and will give the screen a chance to gradually transition off. /// </summary> public void ExitScreen() { if (TransitionOffTime == TimeSpan.Zero) { // If the screen has a zero transition time, remove it immediately. ScreenManager.RemoveScreen(this); } else { // Otherwise flag that it should transition off and then exit. isExiting = true; } } #endregion #region Helper Methods /// <summary> /// A helper method which loads assets using the screen manager's /// associated game content loader. /// </summary> /// <typeparam name="T">Type of asset.</typeparam> /// <param name="assetName">Asset name, relative to the loader root /// directory, and not including the .xnb extension.</param> /// <returns></returns> public T Load<T>(string assetName) { return ScreenManager.Game.Content.Load<T>(assetName); } #endregion } }

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  • Connecting to SQL database using SQLCMD

    - by kaleidoscope
    As we all know, there are a number of ways you can connect to your SQL Azure Database. One of the quick options is to try to connect to SQL server is SQLCMD. To start the SQLCMD utility and connect to a named instance of SQL Server Open a Command Prompt window, and type sqlcmd -S myServer\instanceName. Replace myServer\instanceName with the name of the computer and the instance of SQL Server that you want to connect to. Press ENTER. The sqlcmd prompt (1>) indicates that you are connected to the specified instance of SQL Server. SQL Management Studio offers the facility to use SQLCMD from within SQL scripts by using SQLCMD Mode. How to: Enable SQLCMD mode in the Transact-SQL Editor (About how to start the editor, see How to: Start the Transact-SQL Editor.) To toggle SQLCMD mode from the Data menu 1. Open the query in the Transact-SQL editor. 2. On the Data menu, point to Transact-SQL Editor, and click SQLCMD Mode. To toggle SQLCMD mode from the toolbar 1. Open the query in the Transact-SQL editor. 2. On the Transact-SQL Editor toolbar, click SQLCMD Mode. To toggle SQLCMD mode from the shortcut menu 1. Open the query in the Transact-SQL editor. 2. Right-click anywhere in the editor window, and then click SQLCMD Mode. For more information follow below link http://msdn.microsoft.com/en-us/library/ms170207.aspx   Geeta, G

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  • Making Sense of ASP.NET Paths

    - by Renso
    Making Sense of ASP.NET Paths ASP.Net includes quite a plethora of properties to retrieve path information about the current request, control and application. There's a ton of information available about paths on the Request object, some of it appearing to overlap and some of it buried several levels down, and it can be confusing to find just the right path that you are looking for. To keep things straight I thought it a good idea to summarize the path options along with descriptions and example paths. I wrote a post about this a long time ago in 2004 and I find myself frequently going back to that page to quickly figure out which path I’m looking for in processing the current URL. Apparently a lot of people must be doing the same, because the original post is the second most visited even to this date on this blog to the tune of nearly 500 hits per day. So, I decided to update and expand a bit on the original post with a little more information and clarification based on the original comments. Request Object Paths Available Here's a list of the Path related properties on the Request object (and the Page object). Assume a path like http://www.west-wind.com/webstore/admin/paths.aspx for the paths below where webstore is the name of the virtual. Request Property Description and Value ApplicationPath Returns the web root-relative logical path to the virtual root of this app. /webstore/ PhysicalApplicationPath Returns local file system path of the virtual root for this app. c:\inetpub\wwwroot\webstore PhysicalPath Returns the local file system path to the current script or path. c:\inetpub\wwwroot\webstore\admin\paths.aspx Path FilePath CurrentExecutionFilePath All of these return the full root relative logical path to the script page including path and scriptname. CurrentExcecutionFilePath will return the ‘current’ request path after a Transfer/Execute call while FilePath will always return the original request’s path. /webstore/admin/paths.aspx AppRelativeCurrentExecutionFilePath Returns an ASP.NET root relative virtual path to the script or path for the current request. If in  a Transfer/Execute call the transferred Path is returned. ~/admin/paths.aspx PathInfo Returns any extra path following the script name. If no extra path is provided returns the root-relative path (returns text in red below). string.Empty if no PathInfo is available. /webstore/admin/paths.aspx/ExtraPathInfo RawUrl Returns the full root relative URL including querystring and extra path as a string. /webstore/admin/paths.aspx?sku=wwhelp40 Url Returns a fully qualified URL including querystring and extra path. Note this is a Uri instance rather than string. http://www.west-wind.com/webstore/admin/paths.aspx?sku=wwhelp40 UrlReferrer The fully qualified URL of the page that sent the request. This is also a Uri instance and this value is null if the page was directly accessed by typing into the address bar or using an HttpClient based Referrer client Http header. http://www.west-wind.com/webstore/default.aspx?Info Control.TemplateSourceDirectory Returns the logical path to the folder of the page, master or user control on which it is called. This is useful if you need to know the path only to a Page or control from within the control. For non-file controls this returns the Page path. /webstore/admin/ As you can see there’s a ton of information available there for each of the three common path formats: Physical Path is an OS type path that points to a path or file on disk. Logical Path is a Web path that is relative to the Web server’s root. It includes the virtual plus the application relative path. ~/ (Root-relative) Path is an ASP.NET specific path that includes ~/ to indicate the virtual root Web path. ASP.NET can convert virtual paths into either logical paths using Control.ResolveUrl(), or physical paths using Server.MapPath(). Root relative paths are useful for specifying portable URLs that don’t rely on relative directory structures and very useful from within control or component code. You should be able to get any necessary format from ASP.NET from just about any path or script using these mechanisms. ~/ Root Relative Paths and ResolveUrl() and ResolveClientUrl() ASP.NET supports root-relative virtual path syntax in most of its URL properties in Web Forms. So you can easily specify a root relative path in a control rather than a location relative path: <asp:Image runat="server" ID="imgHelp" ImageUrl="~/images/help.gif" /> ASP.NET internally resolves this URL by using ResolveUrl("~/images/help.gif") to arrive at the root-relative URL of /webstore/images/help.gif which uses the Request.ApplicationPath as the basepath to replace the ~. By convention any custom Web controls also should use ResolveUrl() on URL properties to provide the same functionality. In your own code you can use Page.ResolveUrl() or Control.ResolveUrl() to accomplish the same thing: string imgPath = this.ResolveUrl("~/images/help.gif"); imgHelp.ImageUrl = imgPath; Unfortunately ResolveUrl() is limited to WebForm pages, so if you’re in an HttpHandler or Module it’s not available. ASP.NET Mvc also has it’s own more generic version of ResolveUrl in Url.Decode: <script src="<%= Url.Content("~/scripts/new.js") %>" type="text/javascript"></script> which is part of the UrlHelper class. In ASP.NET MVC the above sort of syntax is actually even more crucial than in WebForms due to the fact that views are not referencing specific pages but rather are often path based which can lead to various variations on how a particular view is referenced. In a Module or Handler code Control.ResolveUrl() unfortunately is not available which in retrospect seems like an odd design choice – URL resolution really should happen on a Request basis not as part of the Page framework. Luckily you can also rely on the static VirtualPathUtility class: string path = VirtualPathUtility.ToAbsolute("~/admin/paths.aspx"); VirtualPathUtility also many other quite useful methods for dealing with paths and converting between the various kinds of paths supported. One thing to watch out for is that ToAbsolute() will throw an exception if a query string is provided and doesn’t work on fully qualified URLs. I wrote about this topic with a custom solution that works fully qualified URLs and query strings here (check comments for some interesting discussions too). Similar to ResolveUrl() is ResolveClientUrl() which creates a fully qualified HTTP path that includes the protocol and domain name. It’s rare that this full resolution is needed but can be useful in some scenarios. Mapping Virtual Paths to Physical Paths with Server.MapPath() If you need to map root relative or current folder relative URLs to physical URLs or you can use HttpContext.Current.Server.MapPath(). Inside of a Page you can do the following: string physicalPath = Server.MapPath("~/scripts/ww.jquery.js")); MapPath is pretty flexible and it understands both ASP.NET style virtual paths as well as plain relative paths, so the following also works. string physicalPath = Server.MapPath("scripts/silverlight.js"); as well as dot relative syntax: string physicalPath = Server.MapPath("../scripts/jquery.js"); Once you have the physical path you can perform standard System.IO Path and File operations on the file. Remember with physical paths and IO or copy operations you need to make sure you have permissions to access files and folders based on the Web server user account that is active (NETWORK SERVICE, ASPNET typically). Note the Server.MapPath will not map up beyond the virtual root of the application for security reasons. Server and Host Information Between these settings you can get all the information you may need to figure out where you are at and to build new Url if necessary. If you need to build a URL completely from scratch you can get access to information about the server you are accessing: Server Variable Function and Example SERVER_NAME The of the domain or IP Address wwww.west-wind.com or 127.0.0.1 SERVER_PORT The port that the request runs under. 80 SERVER_PORT_SECURE Determines whether https: was used. 0 or 1 APPL_MD_PATH ADSI DirectoryServices path to the virtual root directory. Note that LM typically doesn’t work for ADSI access so you should replace that with LOCALHOST or the machine’s NetBios name. /LM/W3SVC/1/ROOT/webstore Request.Url and Uri Parsing If you still need more control over the current request URL or  you need to create new URLs from an existing one, the current Request.Url Uri property offers a lot of control. Using the Uri class and UriBuilder makes it easy to retrieve parts of a URL and create new URLs based on existing URL. The UriBuilder class is the preferred way to create URLs – much preferable over creating URIs via string concatenation. Uri Property Function Scheme The URL scheme or protocol prefix. http or https Port The port if specifically specified. DnsSafeHost The domain name or local host NetBios machine name www.west-wind.com or rasnote LocalPath The full path of the URL including script name and extra PathInfo. /webstore/admin/paths.aspx Query The query string if any ?id=1 The Uri class itself is great for retrieving Uri parts, but most of the properties are read only if you need to modify a URL in order to change it you can use the UriBuilder class to load up an existing URL and modify it to create a new one. Here are a few common operations I’ve needed to do to get specific URLs: Convert the Request URL to an SSL/HTTPS link For example to take the current request URL and converted  it to a secure URL can be done like this: UriBuilder build = new UriBuilder(Request.Url); build.Scheme = "https"; build.Port = -1; // don't inject portUri newUri = build.Uri; string newUrl = build.ToString(); Retrieve the fully qualified URL without a QueryString AFAIK, there’s no native routine to retrieve the current request URL without the query string. It’s easy to do with UriBuilder however: UriBuilder builder = newUriBuilder(Request.Url); builder.Query = ""; stringlogicalPathWithoutQuery = builder.ToString();

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  • Using Take and skip keyword to filter records in LINQ

    - by vik20000in
    In LINQ we can use the take keyword to filter out the number of records that we want to retrieve from the query. Let’s say we want to retrieve only the first 5 records for the list or array then we can use the following query     int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };     var first3Numbers = numbers.Take(3); The TAKE keyword can also be easily applied to list of object in the following way. var first3WAOrders = (         from cust in customers         from order in cust.Orders         select cust ) .Take(3); [Note in the query above we are using the order clause so that the data is first ordered based on the orders field and then the first 3 records are taken. In both the above example we have been able to filter out data based on the number of records we want to fetch. But in both the cases we were fetching the records from the very beginning. But there can be some requirements whereby we want to fetch the records after skipping some of the records like in paging. For this purpose LINQ has provided us with the skip method which skips the number of records passed as parameter in the result set. int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 }; var allButFirst4Numbers = numbers.Skip(4); The SKIP keyword can also be easily applied to list of object in the following way. var first3WAOrders = (         from cust in customers         from order in cust.Orders         select cust ).Skip(3);  Vikram

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  • O&rsquo;Reilly E-Book of the Day 15/Aug/2014 - Advanced Quantitative Finance with C++

    - by TATWORTH
    Originally posted on: http://geekswithblogs.net/TATWORTH/archive/2014/08/15/orsquoreilly-e-book-of-the-day-15aug2014---advanced-quantitative-finance.aspxToday’s half-price book of the Day offer from O’Reilly at http://shop.oreilly.com/product/9781782167228.do?code=MSDEAL is Advanced Quantitative Finance with C++. “This book will introduce you to the key mathematical models used to price financial derivatives, as well as the implementation of main numerical models used to solve them. In particular, equity, currency, interest rates, and credit derivatives are discussed. In the first part of the book, the main mathematical models used in the world of financial derivatives are discussed. Next, the numerical methods used to solve the mathematical models are presented. Finally, both the mathematical models and the numerical methods are used to solve some concrete problems in equity, forex, interest rate, and credit derivatives.”

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  • ASP.NET Web API and Simple Value Parameters from POSTed data

    - by Rick Strahl
    In testing out various features of Web API I've found a few oddities in the way that the serialization is handled. These are probably not super common but they may throw you for a loop. Here's what I found. Simple Parameters from Xml or JSON Content Web API makes it very easy to create action methods that accept parameters that are automatically parsed from XML or JSON request bodies. For example, you can send a JavaScript JSON object to the server and Web API happily deserializes it for you. This works just fine:public string ReturnAlbumInfo(Album album) { return album.AlbumName + " (" + album.YearReleased.ToString() + ")"; } However, if you have methods that accept simple parameter types like strings, dates, number etc., those methods don't receive their parameters from XML or JSON body by default and you may end up with failures. Take the following two very simple methods:public string ReturnString(string message) { return message; } public HttpResponseMessage ReturnDateTime(DateTime time) { return Request.CreateResponse<DateTime>(HttpStatusCode.OK, time); } The first one accepts a string and if called with a JSON string from the client like this:var client = new HttpClient(); var result = client.PostAsJsonAsync<string>(http://rasxps/AspNetWebApi/albums/rpc/ReturnString, "Hello World").Result; which results in a trace like this: POST http://rasxps/AspNetWebApi/albums/rpc/ReturnString HTTP/1.1Content-Type: application/json; charset=utf-8Host: rasxpsContent-Length: 13Expect: 100-continueConnection: Keep-Alive "Hello World" produces… wait for it: null. Sending a date in the same fashion:var client = new HttpClient(); var result = client.PostAsJsonAsync<DateTime>(http://rasxps/AspNetWebApi/albums/rpc/ReturnDateTime, new DateTime(2012, 1, 1)).Result; results in this trace: POST http://rasxps/AspNetWebApi/albums/rpc/ReturnDateTime HTTP/1.1Content-Type: application/json; charset=utf-8Host: rasxpsContent-Length: 30Expect: 100-continueConnection: Keep-Alive "\/Date(1325412000000-1000)\/" (yes still the ugly MS AJAX date, yuk! This will supposedly change by RTM with Json.net used for client serialization) produces an error response: The parameters dictionary contains a null entry for parameter 'time' of non-nullable type 'System.DateTime' for method 'System.Net.Http.HttpResponseMessage ReturnDateTime(System.DateTime)' in 'AspNetWebApi.Controllers.AlbumApiController'. An optional parameter must be a reference type, a nullable type, or be declared as an optional parameter. Basically any simple parameters are not parsed properly resulting in null being sent to the method. For the string the call doesn't fail, but for the non-nullable date it produces an error because the method can't handle a null value. This behavior is a bit unexpected to say the least, but there's a simple solution to make this work using an explicit [FromBody] attribute:public string ReturnString([FromBody] string message) andpublic HttpResponseMessage ReturnDateTime([FromBody] DateTime time) which explicitly instructs Web API to read the value from the body. UrlEncoded Form Variable Parsing Another similar issue I ran into is with POST Form Variable binding. Web API can retrieve parameters from the QueryString and Route Values but it doesn't explicitly map parameters from POST values either. Taking our same ReturnString function from earlier and posting a message POST variable like this:var formVars = new Dictionary<string,string>(); formVars.Add("message", "Some Value"); var content = new FormUrlEncodedContent(formVars); var client = new HttpClient(); var result = client.PostAsync(http://rasxps/AspNetWebApi/albums/rpc/ReturnString, content).Result; which produces this trace: POST http://rasxps/AspNetWebApi/albums/rpc/ReturnString HTTP/1.1Content-Type: application/x-www-form-urlencodedHost: rasxpsContent-Length: 18Expect: 100-continue message=Some+Value When calling ReturnString:public string ReturnString(string message) { return message; } unfortunately it does not map the message value to the message parameter. This sort of mapping unfortunately is not available in Web API. Web API does support binding to form variables but only as part of model binding, which binds object properties to the POST variables. Sending the same message as in the previous example you can use the following code to pick up POST variable data:public string ReturnMessageModel(MessageModel model) { return model.Message; } public class MessageModel { public string Message { get; set; }} Note that the model is bound and the message form variable is mapped to the Message property as would other variables to properties if there were more. This works but it's not very dynamic. There's no real easy way to retrieve form variables (or query string values for that matter) in Web API's Request object as far as I can discern. Well only if you consider this easy:public string ReturnString() { var formData = Request.Content.ReadAsAsync<FormDataCollection>().Result; return formData.Get("message"); } Oddly FormDataCollection does not allow for indexers to work so you have to use the .Get() method which is rather odd. If you're running under IIS/Cassini you can always resort to the old and trusty HttpContext access for request data:public string ReturnString() { return HttpContext.Current.Request.Form["message"]; } which works fine and is easier. It's kind of a bummer that HttpRequestMessage doesn't expose some sort of raw Request object that has access to dynamic data - given that it's meant to serve as a generic REST/HTTP API that seems like a crucial missing piece. I don't see any way to read query string values either. To me personally HttpContext works, since I don't see myself using self-hosted code much.© Rick Strahl, West Wind Technologies, 2005-2012Posted in Web Api   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • How-to filter table filter input to only allow numeric input

    - by frank.nimphius
    In a previous ADF Code Corner post, I explained how to change the table filter behavior by intercepting the query condition in a query filter. See sample #30 at http://www.oracle.com/technetwork/developer-tools/adf/learnmore/index-101235.html In this OTN Harvest post I explain how to prevent users from providing invalid character entries as table filter criteria to avoid problems upon re-querying the table. In the example shown next, only numeric values are allowed for a table column filter. To create a table that allows data filtering, drag a View Object – or a data collection of a Web Service or JPA business service – from the DataControls panel and drop it as a table. Choose the Enable Filtering option in the Edit Table Columns dialog so the table renders with the column filter boxes displayed. The table filter fields are created using implicit af:inputText components that need to be customized for you to apply a custom filter input component, or to change the input behavior. To change the input filter, so only a defined set of input keys is allowed, you need to change the default filter field with your own af:inputText field to which you apply an af:clientListener tag that filters user keyboard entries. For this, in the Oracle JDeveloper visual editor, select the column which filter you want to change and expand the column node in the Oracle JDeveloper Structure Window. Part of the column definition is the Column facet node. Expand the facets so you see the filter facet entry. The filter facet is grayed out as there is no custom facet defined. In a next step, open theComponent Palette (ctrl+shift+P) and drag an Input Text component onto the facet. This demarks the first part in the filter customization. To make the custom filter component work, you need to map the af:inputText component value property to the ADF filter criteria that is exposed in the Expression Builder. Open the Expression Builder for the filter input component value property by clicking the arrow icon to its right. In the Expression Builder expand the JSP Objects | vs | filterCriteria node to select the attribute name represented by the table column. The vs entry is the name of a variable that is defined on the table and that grants you access to the table attributes. Now that the filter works as before – though using a custom filter input component – you can add the af:clientListener tag to your custom filter component – af:inputText – to call out to JavaScript when users type in the column filter field Point the client filter method property to a JavaScript function that you reference or add through using the af:resource tag and set the type property value to keyDown. <af:document id="d1">     <af:resource type="javascript" source="/js/filterHandler.js"/> … The filter definition looks as shown below <af:inputText label="Label 1" id="it1"                         value="#{vs.filterCriteria.Employe        <af:clientListener method="suppressCharacterInput"                                     type="keyDown"/> </af:inputText> The JavaScript code that you can use to either filter character inputs or numeric inputs is shown below. Just store this code in an external JavaScript (.js) file and reference it from the af:resource tag. //Allow numbers, cursor control keys and delete keys function suppressCharacterInput(evt) {     var _keyCode = evt.getKeyCode();     var _filterField = evt.getCurrentTarget();     var _oldValue = _filterField.getValue();     if (!((_keyCode < 57) ||(_keyCode > 96 && _keyCode < 105))) {         _filterField.setValue(_oldValue);         evt.cancel();     } } //Allow characters, cursor control keys and delete keys function suppressNumericInput(evt) {  var _keyCode = evt.getKeyCode();  var _filterField = evt.getCurrentTarget();  var _oldValue = _filterField.getValue();  //check for numbers  if ((_keyCode < 57 && _keyCode > 47) ||      (_keyCode > 96 && _keyCode < 105)){     _filterField.setValue(_oldValue);     evt.cancel();   } } But what if browsers don't allow JavaScript ? Don't worry about this. If browsers would not support JavaScript then ADF Faces as a whole would not work and you had a different problem.

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  • Street-Fighting Mathematics

    Sanjoy Mahajan's new book lays out practical tools for educated guessing and down-and-dirty problem-solving Problem solving - Math - Recreations - Competitions - Methods and Theories

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  • UPK 3.6.1 New Feature - Publish Presentation

    - by peter.maravelias
    UPK includes numerous options for deploying the content you have created. Most UPK users are familiar with the UPK Player and the various document outputs that have been available as publishing formats for some time now. In addition UPK provides the content developer the ability to publish content for use in specific environments, LMS, Test Director are two examples. UPK 3.6.1 adds the Presentation publishing type. The Presentation publishing type produces a slideshow presentation of screenshots and text of each topic as a separate Microsoft PowerPoint file. To publish to the presentation option just select the type under the documents category in the publishing wizard. Give this new publishing type a try and let us know what you think by posting a comment. The Presentation publishing type feature came from a customer request and given the ever growing methods and channels for communication we'd like to know what other output types or methods of using existing outputs you would like to see in a future release of UPK.

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  • Multicast delegates in c#

    - by Jalpesh P. Vadgama
    In yesterday’s post We learn about Delegates and how we can use delegates in C#. In today’s blog post we are going to learn about Multicast delegates. What is Multicast Delegates? As we all know we can assign methods as object to delegate and later on we can call that method with the help delegates. We can also assign more then methods to delegates that is called Multicast delegates. It’s provide functionality to execute more then method at a time. It’s maintain delegates as invocation list (linked list). Let’s understands that via a example. We are going to use yesterday’s example and then we will extend that code multicast delegates. Following code I have written to demonstrate the multicast delegates. using System; namespace Delegates { class Program { public delegate void CalculateNumber(int a, int b); static void Main(string[] args) { int a = 5; int b = 5; CalculateNumber addNumber = new CalculateNumber(AddNumber); CalculateNumber multiplyNumber = new CalculateNumber(MultiplyNumber); CalculateNumber multiCast = (CalculateNumber)Delegate.Combine (addNumber, multiplyNumber); multiCast.Invoke(a,b); Console.ReadLine(); } public static void AddNumber(int a, int b) { Console.WriteLine("Adding Number"); Console.WriteLine(5 + 6); } public static void MultiplyNumber(int a, int b) { Console.WriteLine("Multiply Number"); Console.WriteLine(5 + 6); } } } As you can see in the above code I have created two method one for adding two numbers and another for multiply two number. After that I have created two same CalculateNumber delegates addNumber and multiplyNumber then I have create a multicast delegates multiCast with combining two delegates. Now I want to call this both method so I have used Invoke method to call this delegates. As now our code is let’s run the application. Following is a output as expected. As you can we can execute multiple methods with multicast delegates the only thing you need to take care is that we need to type for both delegates. That’s it. Hope you like it. Stay tuned for more.. Till then happy programming.

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  • Lync Server 2010

    - by ManojDhobale
    Microsoft Lync Server 2010 communications software and its client software, such as Microsoft Lync 2010, enable your users to connect in new ways and to stay connected, regardless of their physical location. Lync 2010 and Lync Server 2010 bring together the different ways that people communicate in a single client interface, are deployed as a unified platform, and are administered through a single management infrastructure. Workload Description IM and presence Instant messaging (IM) and presence help your users find and communicate with one another efficiently and effectively. IM provides an instant messaging platform with conversation history, and supports public IM connectivity with users of public IM networks such as MSN/Windows Live, Yahoo!, and AOL. Presence establishes and displays a user’s personal availability and willingness to communicate through the use of common states such as Available or Busy. This rich presence information enables other users to immediately make effective communication choices. Conferencing Lync Server includes support for IM conferencing, audio conferencing, web conferencing, video conferencing, and application sharing, for both scheduled and impromptu meetings. All these meeting types are supported with a single client. Lync Server also supports dial-in conferencing so that users of public switched telephone network (PSTN) phones can participate in the audio portion of conferences. Conferences can seamlessly change and grow in real time. For example, a single conference can start as just instant messages between a few users, and escalate to an audio conference with desktop sharing and a larger audience instantly, easily, and without interrupting the conversation flow. Enterprise Voice Enterprise Voice is the Voice over Internet Protocol (VoIP) offering in Lync Server 2010. It delivers a voice option to enhance or replace traditional private branch exchange (PBX) systems. In addition to the complete telephony capabilities of an IP PBX, Enterprise Voice is integrated with rich presence, IM, collaboration, and meetings. Features such as call answer, hold, resume, transfer, forward and divert are supported directly, while personalized speed dialing keys are replaced by Contacts lists, and automatic intercom is replaced with IM. Enterprise Voice supports high availability through call admission control (CAC), branch office survivability, and extended options for data resiliency. Support for remote users You can provide full Lync Server functionality for users who are currently outside your organization’s firewalls by deploying servers called Edge Servers to provide a connection for these remote users. These remote users can connect to conferences by using a personal computer with Lync 2010 installed, the phone, or a web interface. Deploying Edge Servers also enables you to federate with partner or vendor organizations. A federated relationship enables your users to put federated users on their Contacts lists, exchange presence information and instant messages with these users, and invite them to audio calls, video calls, and conferences. Integration with other products Lync Server integrates with several other products to provide additional benefits to your users and administrators. Meeting tools are integrated into Outlook 2010 to enable organizers to schedule a meeting or start an impromptu conference with a single click and make it just as easy for attendees to join. Presence information is integrated into Outlook 2010 and SharePoint 2010. Exchange Unified Messaging (UM) provides several integration features. Users can see if they have new voice mail within Lync 2010. They can click a play button in the Outlook message to hear the audio voice mail, or view a transcription of the voice mail in the notification message. Simple deployment To help you plan and deploy your servers and clients, Lync Server provides the Microsoft Lync Server 2010, Planning Tool and the Topology Builder. Lync Server 2010, Planning Tool is a wizard that interactively asks you a series of questions about your organization, the Lync Server features you want to enable, and your capacity planning needs. Then, it creates a recommended deployment topology based on your answers, and produces several forms of output to aid your planning and installation. Topology Builder is an installation component of Lync Server 2010. You use Topology Builder to create, adjust and publish your planned topology. It also validates your topology before you begin server installations. When you install Lync Server on individual servers, the installation program deploys the server as directed in the topology. Simple management After you deploy Lync Server, it offers the following powerful and streamlined management tools: Active Directory for its user information, which eliminates the need for separate user and policy databases. Microsoft Lync Server 2010 Control Panel, a new web-based graphical user interface for administrators. With this web-based UI, Lync Server administrators can manage their systems from anywhere on the corporate network, without needing specialized management software installed on their computers. Lync Server Management Shell command-line management tool, which is based on the Windows PowerShell command-line interface. It provides a rich command set for administration of all aspects of the product, and enables Lync Server administrators to automate repetitive tasks using a familiar tool. While the IM and presence features are automatically installed in every Lync Server deployment, you can choose whether to deploy conferencing, Enterprise Voice, and remote user access, to tailor your deployment to your organization’s needs.

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  • Logparser and Powershell

    - by Michel Klomp
    Logparser in powershell One of the few examples how to use logparser in powershell is from the Microsoft.com Operations blog. This script is a good base to create more advanced logparser scripts: $myQuery = new-object -com MSUtil.LogQuery $szQuery = “Select top 10 * from r:\ex07011210.log”; $recordSet = $myQuery.Execute($szQuery) for(; !$recordSet.atEnd(); $recordSet.moveNext()) {             $record=$recordSet.getRecord();             write-host ($record.GetValue(0) + “,”+ $record.GetValue(1)); } $recordSet.Close(); Logparser input formats The previous example uses the default logparser object, you can extent this with the logparser input formats. with this formats get information from the event-log, different types of logfiles, the Active Directory, the registry and XML files. Here are the different ProgId’s you can use. Input Format ProgId ADS MSUtil.LogQuery.ADSInputFormat BIN MSUtil.LogQuery.IISBINInputFormat CSV MSUtil.LogQuery.CSVInputFormat ETW MSUtil.LogQuery.ETWInputFormat EVT MSUtil.LogQuery.EventLogInputFormat FS MSUtil.LogQuery.FileSystemInputFormat HTTPERR MSUtil.LogQuery.HttpErrorInputFormat IIS MSUtil.LogQuery.IISIISInputFormat IISODBC MSUtil.LogQuery.IISODBCInputFormat IISW3C MSUtil.LogQuery.IISW3CInputFormat NCSA MSUtil.LogQuery.IISNCSAInputFormat NETMON MSUtil.LogQuery.NetMonInputFormat REG MSUtil.LogQuery.RegistryInputFormat TEXTLINE MSUtil.LogQuery.TextLineInputFormat TEXTWORD MSUtil.LogQuery.TextWordInputFormat TSV MSUtil.LogQuery.TSVInputFormat URLSCAN MSUtil.LogQuery.URLScanLogInputFormat W3C MSUtil.LogQuery.W3CInputFormat XML MSUtil.LogQuery.XMLInputFormat Using logparser to parse IIS logs if you use the IISW3CinputFormat you can use the field names instead of de row number to get the information from an IIS logfile, it also skips the comment rows in the logfile. $ObjLogparser = new-object -com MSUtil.LogQuery $objInputFormat = new-object -com MSUtil.LogQuery.IISW3CInputFormat $Query = “Select top 10 * from c:\temp\hb\ex071002.log”; $recordSet = $ObjLogparser.Execute($Query, $objInputFormat) for(; !$recordSet.atEnd(); $recordSet.moveNext()) {     $record=$recordSet.getRecord();     write-host ($record.GetValue(“s-ip”) + “,”+ $record.GetValue(“cs-uri-query”)); } $recordSet.Close();

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  • CLR via C# 3rd Edition is out

    - by Abhijeet Patel
    Time for some book news update. CLR via C#, 3rd Edition seems to have been out for a little while now. The book was released in early Feb this year, and needless to say my copy is on it’s way. I can barely wait to dig in and chew on the goodies that one of the best technical authors and software professionals I respect has in store. The 2nd edition of the book was an absolute treat and this edition promises to be no less. Here is a brief description of what’s new and updated from the 2nd edition. Part I – CLR Basics Chapter 1-The CLR’s Execution Model Added about discussion about C#’s /optimize and /debug switches and how they relate to each other. Chapter 2-Building, Packaging, Deploying, and Administering Applications and Types Improved discussion about Win32 manifest information and version resource information. Chapter 3-Shared Assemblies and Strongly Named Assemblies Added discussion of TypeForwardedToAttribute and TypeForwardedFromAttribute. Part II – Designing Types Chapter 4-Type Fundamentals No new topics. Chapter 5-Primitive, Reference, and Value Types Enhanced discussion of checked and unchecked code and added discussion of new BigInteger type. Also added discussion of C# 4.0’s dynamic primitive type. Chapter 6-Type and Member Basics No new topics. Chapter 7-Constants and Fields No new topics. Chapter 8-Methods Added discussion of extension methods and partial methods. Chapter 9-Parameters Added discussion of optional/named parameters and implicitly-typed local variables. Chapter 10-Properties Added discussion of automatically-implemented properties, properties and the Visual Studio debugger, object and collection initializers, anonymous types, the System.Tuple type and the ExpandoObject type. Chapter 11-Events Added discussion of events and thread-safety as well as showing a cool extension method to simplify the raising of an event. Chapter 12-Generics Added discussion of delegate and interface generic type argument variance. Chapter 13-Interfaces No new topics. Part III – Essential Types Chapter 14-Chars, Strings, and Working with Text No new topics. Chapter 15-Enums Added coverage of new Enum and Type methods to access enumerated type instances. Chapter 16-Arrays Added new section on initializing array elements. Chapter 17-Delegates Added discussion of using generic delegates to avoid defining new delegate types. Also added discussion of lambda expressions. Chapter 18-Attributes No new topics. Chapter 19-Nullable Value Types Added discussion on performance. Part IV – CLR Facilities Chapter 20-Exception Handling and State Management This chapter has been completely rewritten. It is now about exception handling and state management. It includes discussions of code contracts and constrained execution regions (CERs). It also includes a new section on trade-offs between writing productive code and reliable code. Chapter 21-Automatic Memory Management Added discussion of C#’s fixed state and how it works to pin objects in the heap. Rewrote the code for weak delegates so you can use them with any class that exposes an event (the class doesn’t have to support weak delegates itself). Added discussion on the new ConditionalWeakTable class, GC Collection modes, Full GC notifications, garbage collection modes and latency modes. I also include a new sample showing how your application can receive notifications whenever Generation 0 or 2 collections occur. Chapter 22-CLR Hosting and AppDomains Added discussion of side-by-side support allowing multiple CLRs to be loaded in a single process. Added section on the performance of using MarshalByRefObject-derived types. Substantially rewrote the section on cross-AppDomain communication. Added section on AppDomain Monitoring and first chance exception notifications. Updated the section on the AppDomainManager class. Chapter 23-Assembly Loading and Reflection Added section on how to deploy a single file with dependent assemblies embedded inside it. Added section comparing reflection invoke vs bind/invoke vs bind/create delegate/invoke vs C#’s dynamic type. Chapter 24-Runtime Serialization This is a whole new chapter that was not in the 2nd Edition. Part V – Threading Chapter 25-Threading Basics Whole new chapter motivating why Windows supports threads, thread overhead, CPU trends, NUMA Architectures, the relationship between CLR threads and Windows threads, the Thread class, reasons to use threads, thread scheduling and priorities, foreground thread vs background threads. Chapter 26-Performing Compute-Bound Asynchronous Operations Whole new chapter explaining the CLR’s thread pool. This chapter covers all the new .NET 4.0 constructs including cooperative cancelation, Tasks, the aralle class, parallel language integrated query, timers, how the thread pool manages its threads, cache lines and false sharing. Chapter 27-Performing I/O-Bound Asynchronous Operations Whole new chapter explaining how Windows performs synchronous and asynchronous I/O operations. Then, I go into the CLR’s Asynchronous Programming Model, my AsyncEnumerator class, the APM and exceptions, Applications and their threading models, implementing a service asynchronously, the APM and Compute-bound operations, APM considerations, I/O request priorities, converting the APM to a Task, the event-based Asynchronous Pattern, programming model soup. Chapter 28-Primitive Thread Synchronization Constructs Whole new chapter discusses class libraries and thread safety, primitive user-mode, kernel-mode constructs, and data alignment. Chapter 29-Hybrid Thread Synchronization Constructs Whole new chapter discussion various hybrid constructs such as ManualResetEventSlim, SemaphoreSlim, CountdownEvent, Barrier, ReaderWriterLock(Slim), OneManyResourceLock, Monitor, 3 ways to solve the double-check locking technique, .NET 4.0’s Lazy and LazyInitializer classes, the condition variable pattern, .NET 4.0’s concurrent collection classes, the ReaderWriterGate and SyncGate classes.

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  • My View on ASP.NET Web Forms versus MVC

    - by Ricardo Peres
    Introduction A lot has been said on Web Forms and MVC, but since I was recently asked about my opinion on the subject, here it is. First, I have to say that I really like both technologies and I don’t think any is going away – just remember SharePoint, which is built on top of Web Forms. I see them as complementary, targeting different needs and leveraging different skills. Let’s go through some of their differences. Rapid Application Development Rapid Application Development (RAD) is the development process by which you have an Integrated Development Environment (IDE), a visual design surface and a toolbox, and you drag components from the toolbox to the design surface and set their properties through a property inspector. It was introduced with some of the earliest Windows graphical IDEs such as Visual Basic and Delphi. With Web Forms you have RAD out of the box. Visual Studio offers a generally good (and extensible) designer for the layout of pages and web user controls. Designing a page may simply be about dragging controls from the toolbox, setting their properties and wiring up some events to event handlers, which are implemented in code behind .NET classes. Most people will be familiar with this kind of development and enjoy it. You can see what you are doing from the beginning. MVC also has designable pages – called views in MVC terminology – the problem is that they can be built using different technologies, some of which, at the moment (MVC 4) do not support RAD – Razor, for example. I believe it is just a matter of time for that to be implemented in Visual Studio, but it will mostly consist on HTML editing, and until that day comes, you have to live with source editing. Development Model Web Forms features the same development model that you are used to from Windows Forms and other similar technologies: events fired by controls and automatic persistence of their properties between postbacks. For that, it uses concepts such as view state, which some may love and others may hate, because it may be misused quite easily, but otherwise does its job well. Another fundamental concept is data binding, by which a collection of data can be fed to a control and have it render that data somehow – just thing of the GridView control. The focus is on the page, that’s where it all starts, and you can place everything in the same code behind class: data access, business logic, layout, etc. The controls take care of generating a great part of the HTML and JavaScript for you. With MVC there is no free lunch when it comes to data persistence between requests, you have to implement it yourself. As for event handling, that is at the core of MVC, in the form of controllers and action methods, you just don’t think of them as event handlers. In MVC you need to think more in HTTP terms, so action methods such as POST and GET are relevant to you, and may write actions to handle one or the other. Also of crucial importance is model binding: the way by which MVC converts your posted data into a .NET class. This is something that ASP.NET 4.5 Web Forms has introduced as well, but it is a cornerstone in MVC. MVC also has built-in validation of these .NET classes, which out of the box uses the Data Annotations API. You have full control of the generated HTML - except for that coming from the helper methods, usually small fragments - which requires a greater familiarity with the specifications. You normally rely much more on JavaScript APIs, they are even included in the Visual Studio template, that is because much less is done for you. Reuse It is difficult to accept a professional company/project that does not employ reuse. It can save a lot of time thus cutting costs significantly. Code reused in several projects matures as time goes by and helps developers learn from past experiences. ASP.NET Web Forms was built with reuse in mind, in the form of controls. Controls encapsulate functionality and are generally portable from project to project (with the notable exception of web user controls, those with an associated .ASCX markup file). ASP.NET has dozens of controls and it is very easy to develop new ones, so I believe this is a great advantage. A control can inject JavaScript code and external references as well as generate HTML an CSS. MVC on the other hand does not use controls – it is possible to use them, with some view engines like ASPX, but it is just not advisable because it breaks the flow – where do Init, Load, PreRender, etc, fit? The most similar to controls is extension methods, or helpers. They serve the same purpose – generating HTML, CSS or JavaScript – and can be reused between different projects. What differentiates them from controls is that there is no inheritance and no context – an extension method is just a static method which doesn’t know where it is being called. You also have partial views, which you can reuse in the same project, but there is no inheritance as well. This, in my view, is a weakness of MVC. Architecture Both technologies are highly extensible. I have writtenstarted writing a series of posts on ASP.NET Web Forms extensibility and will probably write another series on MVC extensibility as well. A number of scenarios are covered in any of these models, and some extensibility points apply to both, because, of course both stand upon ASP.NET. With Web Forms, if you’re like me, you start by defining you master pages, pages and controls, with some helper classes to glue everything. You may as well throw in some JavaScript, but probably you’re main work will be with plain old .NET code. The controls you define have the chance to inject JavaScript code and references, through either the ScriptManager or the page’s ClientScript object, as well as generating HTML and CSS code. The master page and page model with code behind classes offer a number of “hooks” by which you can change the normal way of things, for example, in a page you can access any control on the master page, add script or stylesheet references to its head and even change the page’s title. Also, with Web Forms, you typically have URLs in the form “/SomePath/SomePage.aspx?SomeParameter=SomeValue”, which isn’t really SEO friendly, no to mention the HTML that some controls produce, far from standards, optimization and best practices. In MVC, you also normally start by defining the master page (or layout) and views, which are the visible parts, and then define controllers on separate files. These controllers do not know anything about the views, except the names and types of the parameters that will be passed to and from them. The controller will be responsible for the data access and business logic, eventually relying on additional classes for this purpose. On a controller you only receive parameters and return a result, which may be a request for the rendering of a view, a redirection to another URL or a JSON object, to name just a few. The controller class does not know anything about the web, so you can effectively reuse it in a non-web project. This separation and the lack of programmatic access to the UI elements, makes it very difficult to implement, for example, something like SharePoint with MVC. OK, I know about Orchard, but it isn’t really a general purpose development framework, but instead, a CMS that happens to use MVC. Not having controls render HTML for you gives you in turn much more control over it – it is your responsibility to create it, which you can either consider a blessing or a curse, in the later case, you probably shouldn’t be using MVC at all. Also MVC URLs tend to be much more SEO-oriented, if you design your controllers and actions properly. Testing In a well defined architecture, you should separate business logic, data access logic and presentation logic, because these are all different things and it might even be the need to switch one implementation for another: for example, you might design a system which includes a data access layer, a business logic layer and two presentation layers, one on top of ASP.NET and the other with WPF; and the data access layer might be implemented first using NHibernate and later on switched for Entity Framework Code First. These changes are not that rare, so care should be taken in designing the system to make them possible. Web Forms are difficult to test, because it relies on event handlers which are only fired in web contexts, when a form is submitted or a page is requested. You can call them with reflection, but you have to set up a number of mocking objects first, HttpContext.Current first coming to my mind. MVC, on the other hand, makes testing controllers a breeze, so much that it even includes a template option for generating boilerplate unit test classes up from start. A well designed – from the unit test point of view - controller will receive everything it needs to work as parameters to its action methods, so you can pass whatever values you need very easily. That doesn’t mean, of course, that everything can be tested: views, for instance, are difficult to test without actually accessing the site, but MVC offers the possibility to compile views at build time, so that, at least, you know you don’t have syntax errors beforehand. Myths Some popular but unfounded myths around MVC include: You cannot use controls in MVC: not true, actually, you can, at least with the Web Forms (ASPX) view engine; the declaration and usage is exactly the same as with Web Forms; You cannot specify a base class for a view: with the ASPX view engine you can use the Inherits Page directive, with this and all the others you can use the pageBaseType and userControlBaseType attributes of the <page> element; MVC shields you from doing “bad things” on your views: well, you can place any code on a code block, at least with the ASPX view engine (you may be starting to see a pattern here), even data access code; The model is the entity model, tied to an O/RM: the model is actually any class that you use to pass values to a view, including (but generally not recommended) an entity model; Unit tests come with no cost: unit tests generally don’t cover the UI, although there are frameworks just for that (see WatiN, for example); also, for some tests, you will have to mock or replace either the HttpContext.Current property or the HttpContextBase class yourself; Everything is testable: views aren’t, without accessing the site; MVC relies on HTML5/some_cool_new_javascript_framework: there is no relation whatsoever, MVC renders whatever you want it to render and does not require any framework to be present. The thing is, the subsequent releases of MVC happened in a time when Microsoft has become much more involved in standards, so the files and technologies included in the Visual Studio templates reflect this, and it just happens to work well with jQuery, for example. Conclusion Well, this is how I see it. Some folks may think that I am being too rude on MVC, probably because I don’t like it, but that’s not true: like I said, I do like MVC and I am starting my new projects with it. I just don’t want to go along with that those that say that MVC is much superior to Web Forms, in fact, some things you can do much more easily with Web Forms than with MVC. I will be more than happy to hear what you think on this!

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  • Liskov Substitution Principle and the Oft Forgot Third Wheel

    - by Stacy Vicknair
    Liskov Substitution Principle (LSP) is a principle of object oriented programming that many might be familiar with from the SOLID principles mnemonic from Uncle Bob Martin. The principle highlights the relationship between a type and its subtypes, and, according to Wikipedia, is defined by Barbara Liskov and Jeanette Wing as the following principle:   Let be a property provable about objects of type . Then should be provable for objects of type where is a subtype of .   Rectangles gonna rectangulate The iconic example of this principle is illustrated with the relationship between a rectangle and a square. Let’s say we have a class named Rectangle that had a property to set width and a property to set its height. 1: Public Class Rectangle 2: Overridable Property Width As Integer 3: Overridable Property Height As Integer 4: End Class   We all at some point here that inheritance mocks an “IS A” relationship, and by gosh we all know square IS A rectangle. So let’s make a square class that inherits from rectangle. However, squares do maintain the same length on every side, so let’s override and add that behavior. 1: Public Class Square 2: Inherits Rectangle 3:  4: Private _sideLength As Integer 5:  6: Public Overrides Property Width As Integer 7: Get 8: Return _sideLength 9: End Get 10: Set(value As Integer) 11: _sideLength = value 12: End Set 13: End Property 14:  15: Public Overrides Property Height As Integer 16: Get 17: Return _sideLength 18: End Get 19: Set(value As Integer) 20: _sideLength = value 21: End Set 22: End Property 23: End Class   Now, say we had the following test: 1: Public Sub SetHeight_DoesNotAffectWidth(rectangle As Rectangle) 2: 'arrange 3: Dim expectedWidth = 4 4: rectangle.Width = 4 5:  6: 'act 7: rectangle.Height = 7 8:  9: 'assert 10: Assert.AreEqual(expectedWidth, rectangle.Width) 11: End Sub   If we pass in a rectangle, this test passes just fine. What if we pass in a square?   This is where we see the violation of Liskov’s Principle! A square might "IS A” to a rectangle, but we have differing expectations on how a rectangle should function than how a square should! Great expectations Here’s where we pat ourselves on the back and take a victory lap around the office and tell everyone about how we understand LSP like a boss. And all is good… until we start trying to apply it to our work. If I can’t even change functionality on a simple setter without breaking the expectations on a parent class, what can I do with subtyping? Did Liskov just tell me to never touch subtyping again? The short answer: NO, SHE DIDN’T. When I first learned LSP, and from those I’ve talked with as well, I overlooked a very important but not appropriately stressed quality of the principle: our expectations. Our inclination is to want a logical catch-all, where we can easily apply this principle and wipe our hands, drop the mic and exit stage left. That’s not the case because in every different programming scenario, our expectations of the parent class or type will be different. We have to set reasonable expectations on the behaviors that we expect out of the parent, then make sure that those expectations are met by the child. Any expectations not explicitly expected of the parent aren’t expected of the child either, and don’t register as a violation of LSP that prevents implementation. You can see the flexibility mentioned in the Wikipedia article itself: A typical example that violates LSP is a Square class that derives from a Rectangle class, assuming getter and setter methods exist for both width and height. The Square class always assumes that the width is equal with the height. If a Square object is used in a context where a Rectangle is expected, unexpected behavior may occur because the dimensions of a Square cannot (or rather should not) be modified independently. This problem cannot be easily fixed: if we can modify the setter methods in the Square class so that they preserve the Square invariant (i.e., keep the dimensions equal), then these methods will weaken (violate) the postconditions for the Rectangle setters, which state that dimensions can be modified independently. Violations of LSP, like this one, may or may not be a problem in practice, depending on the postconditions or invariants that are actually expected by the code that uses classes violating LSP. Mutability is a key issue here. If Square and Rectangle had only getter methods (i.e., they were immutable objects), then no violation of LSP could occur. What this means is that the above situation with a rectangle and a square can be acceptable if we do not have the expectation for width to leave height unaffected, or vice-versa, in our application. Conclusion – the oft forgot third wheel Liskov Substitution Principle is meant to act as a guidance and warn us against unexpected behaviors. Objects can be stateful and as a result we can end up with unexpected situations if we don’t code carefully. Specifically when subclassing, make sure that the subclass meets the expectations held to its parent. Don’t let LSP think you cannot deviate from the behaviors of the parent, but understand that LSP is meant to highlight the importance of not only the parent and the child class, but also of the expectations WE set for the parent class and the necessity of meeting those expectations in order to help prevent sticky situations.   Code examples, in both VB and C# Technorati Tags: LSV,Liskov Substitution Principle,Uncle Bob,Robert Martin,Barbara Liskov,Liskov

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  • Bonjour/DNS Service Discovery queries

    - by senloe
    I'm trying to implement dns service discovery in my application (no, I'm not asking for a programmatic answer). What I believe is one of my big pain points is generating the query. I know I need to send out a multicast broadcast on port 5353 and want to look for devices of type _ipp._tcp and _print._tcp, but I don't know what the question section needs to look like. For example, in SSDP I sent out a query that looks like the following: "M-SEARCH * HTTP/1.1\r\n" "HOST: 239.255.255.250:1900\r\n" + "MAN: \"ssdp:discover\"\r\n" "ST: urn:schemas-upnp-org:device:Printer:1\r\n" "MX: 5000\r\n\r\n" From what I know about a DNS query I need to send something like: "_ipp.tcp,all,all" but I know there needs to be more. Any pointers to documentation, etc would be greatly appreciated! update rfc1035 appears to contain promising information re the message structure.

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  • Dig returns "status: REFUSED" for external queries?

    - by Mikey
    I can't seem to work out why my DNS isn't working properly, if I run dig from the nameserver it functions correctly: # dig ungl.org ; <<>> DiG 9.5.1-P2.1 <<>> ungl.org ;; global options: printcmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 24585 ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 1 ;; QUESTION SECTION: ;ungl.org. IN A ;; ANSWER SECTION: ungl.org. 38400 IN A 188.165.34.72 ;; AUTHORITY SECTION: ungl.org. 38400 IN NS ns.kimsufi.com. ungl.org. 38400 IN NS r29901.ovh.net. ;; ADDITIONAL SECTION: ns.kimsufi.com. 85529 IN A 213.186.33.199 ;; Query time: 1 msec ;; SERVER: 127.0.0.1#53(127.0.0.1) ;; WHEN: Sat Mar 13 01:04:06 2010 ;; MSG SIZE rcvd: 114 but when I run it from another server in the same datacenter I receive: # dig @87.98.167.208 ungl.org ; <<>> DiG 9.5.1-P2.1 <<>> @87.98.167.208 ungl.org ; (1 server found) ;; global options: printcmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: REFUSED, id: 18787 ;; flags: qr rd; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0 ;; WARNING: recursion requested but not available ;; QUESTION SECTION: ;ungl.org. IN A ;; Query time: 1 msec ;; SERVER: 87.98.167.208#53(87.98.167.208) ;; WHEN: Sat Mar 13 01:01:35 2010 ;; MSG SIZE rcvd: 26 my zone file for this domain is $ttl 38400 ungl.org. IN SOA r29901.ovh.net. mikey.aol.com. ( 201003121 10800 3600 604800 38400 ) ungl.org. IN NS r29901.ovh.net. ungl.org. IN NS ns.kimsufi.com. ungl.org. IN A 188.165.34.72 localhost. IN A 127.0.0.1 www IN A 188.165.34.72 and the named.conf.options is default: options { directory "/var/cache/bind"; // If there is a firewall between you and nameservers you want // to talk to, you may need to fix the firewall to allow multiple // ports to talk. See http://www.kb.cert.org/vuls/id/800113 // If your ISP provided one or more IP addresses for stable // nameservers, you probably want to use them as forwarders. // Uncomment the following block, and insert the addresses replacing // the all-0's placeholder. // forwarders { // 0.0.0.0; // }; auth-nxdomain no; # conform to RFC1035 listen-on-v6 { ::1; }; listen-on { 127.0.0.1; }; allow-recursion { 127.0.0.1; }; }; named.conf.local: // // Do any local configuration here // // Consider adding the 1918 zones here, if they are not used in your // organization // include "/etc/bind/zones.rfc1918"; zone "eugl.eu" { type master; file "/etc/bind/eugl.eu"; notify no; }; zone "ungl.org" { type master; file "/etc/bind/ungl.org"; notify no; }; The server is running Ubuntu 9.10 and Bind 9, if anyone can shed some light on this for me it'd make me very happy! thanks

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  • Fluid VS Responsive Website Development Questions

    - by Aditya P
    As I understand these form the basis for targeting a wide array of devices based on the browser size, given it would be a time consuming to generate different layouts targeting different/specific devices and their resolutions. Questions: Firstly right to the jargon, is there any actual difference between the two or do they mean the same? Is it safe to classify the current development mainly a html5/css3 based one? What popular frameworks are available to easily implement this? What testing methods used in this regard? What are the most common compatibility issues in terms of different browser types? I understand there are methods like this http://css-tricks.com/resolution-specific-stylesheets/ which does this come under?. Are there any external browser detection methods besides the API calls specific to the browser that are employed in this regard? Points of interest [Prior Research before asking these questions] Why shouldn't "responsive" web design be a consideration? Responsive Web Design Tips, Best Practices and Dynamic Image Scaling Techniques A recent list of tutorials 30 Responsive Web Design and Development Tutorials by Eric Shafer on May 14, 2012 Update Ive been reading that the basic point of designing content for different layouts to facilitate a responsive web design is to present the most relevant information. now obviously between the smallest screen width and the highest we are missing out on design elements. I gather from here http://flashsolver.com/2012/03/24/5-top-commercial-responsive-web-designs/ The top of the line design layouts (widths) are desktop layout (980px) tablet layout (768px) smartphone layout – landscape (480px) smartphone layout – portrait (320px) Also we have a popular responsive website testing site http://resizemybrowser.com/ which lists different screen resolutions. I've also come across this while trying to find out the optimal highest layout size to account for http://stackoverflow.com/questions/10538599/default-web-page-width-1024px-or-980px which brings to light seemingly that 1366x768 is a popular web resolution. Is it safe to assume that just accounting for proper scaling from width 980px onwards to the maximum size would be sufficient to accommodate this? given we aren't presenting any new information for the new size. Does it make sense to have additional information ( which conflicts with purpose of responsive web design) to utilize the top size and beyond?

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  • Explain Model View Controller

    - by Channel72
    My experience with developing dynamic websites is limited mostly to Java servlets. I've used Tomcat to develop various Java servlets, and I wouldn't hesitate to say that I'm reasonably proficient with this technology, as well as with client-side HTML/CSS/Javascript for the front-end. When I think "dynamic website", I think: user requests a URL with a query string, server receives the query, and then proceeds to output HTML dynamically in order to respond to the query. This often involves communication with a database in order to fetch requested data for display. This is basically the idea behind the doGet method of a Java HttpServlet. But these days, I'm hearing more and more about newer frameworks such as Django and Ruby on Rails, all of which take advantage of the "Model View Controller" architecture. I've read various articles which explain MVC, but I'm having trouble really understanding the benefits. I understand that the general idea is to separate business logic from UI logic, but I fail to see how this is anything really different from normal web programming. Web programming, by it's very nature, forces you to separate business logic (back-end server-side programming) from UI programming (client-side HTML or Javascript), because the two exist in entirely different spheres of programming. Question: What does MVC offer over something like a Java servlet, and more importantly, what exactly is MVC and how is it different from what you would normally do to develop a dynamic website using a more traditional approach such as a Java servlet (or even something older like CGI). If possible, when explaining MVC, please provide an example which illustrates how MVC is applied to the web development process, and how it is beneficial.

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  • Using Squid on Debian, Cannot Connect Error

    - by Zed Said
    I am trying to set up Squid on Debian and am getting a connection refused error: squidclient http://www.apple.com/ > test client: ERROR: Cannot connect to 127.0.0.1:3128: Connection refused Here is my config: visible_hostname none cache_effective_user proxy cache_effective_group proxy cache_dir ufs /var/spool/squid 2048 16 256 cache_mem 512 MB cache_access_log /var/log/squid/access.log emulate_httpd_log on strip_query_terms off read_ahead_gap 128 Kb collapsed_forwarding on refresh_stale_hit 30 seconds retry_on_error on maximum_object_size_in_memory 1 MB acl all src 0.0.0.0/0.0.0.0 acl purgehosts src 127.0.0.1/255.255.255.255 # Caching static objects in __data is important. # Without that, apache processes sit around spooling static objects. acl QUERY urlpath_regex /cgi-bin/ /_edit /_admin /_login /_nocache /_recache /__lib /__fudge acl PURGE method PURGE acl POST method POST cache deny QUERY cache deny POST http_access allow PURGE purgehosts http_access deny PURGE http_access allow all http_port 127.0.0.1:80 http_port 50.56.206.139:80 cache_peer 127.0.0.1 parent 80 0 originserver no-query no-digest default redirect_rewrites_host_header off read_ahead_gap 128 Kb shutdown_lifetime 5 seconds Any ideas why this is happening? What have I missed?

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  • storing map template in database

    - by Timigen
    I am working on an application that displays choropleth maps. These maps are of all different types, some display state by county, country by state/province, or world by country. How should I handle storing the map information in the database? My Thoughts: I won't need to do queries to find POI inside a region, so I don't think there is a need to use spatial datatypes. I am considering storing a map as a geoJSON object (I am using JS mapping library that accepts geoJSON). The only issue is what if I want a map of the US northeast. Then I would have geoJSON for the US and a separate one for the US northeast, which would be redundant. Would it make sense to have a shape database where I had each state then when I needed a map of the US I could query for each state, and when I needed a map of the US Northeast I could again query for what I need? Note: I am not concerned with storing the data for each region, just the region itself. I will query for the data on the fly for the specific region.

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