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  • XNA 4.0 SpriteBatch.Draw Out Of Memory Exception Thrown

    - by RustyGearGames
    Well, first of all, my guess is that I'm calling the spritebatch.draw() method to many times, but I need to (Or, it's the only way I can figure out how to) Draw my in-game windows. I'll just go ahead and dump my code; using System; using System.Text; using System.Collections.Generic; using System.Linq; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Audio; using Microsoft.Xna.Framework.Content; using Microsoft.Xna.Framework.GamerServices; using Microsoft.Xna.Framework.Graphics; using Microsoft.Xna.Framework.Input; using Microsoft.Xna.Framework.Media; namespace System.Window { class Window { #region Variables public Texture2D importedTexture; public Texture2D WindowSkin; public RenderTarget2D currentWindow; public RenderTarget2D windowTexture; public Vector2 pos; public int prevWindowWidth; public int prevWindowHeight; public int windowWidth; public int windowHeight; public bool visible; public bool active; public bool drawNew; #region Rectangles public Rectangle clickRect; public Rectangle topLeftRect; public Rectangle topRightRect; public Rectangle buttonRect; public Rectangle botLeftRect; public Rectangle botRightRect; #endregion #endregion public Window() { } public void Initialize(GraphicsDevice g, Texture2D ws, Texture2D it, int w, int h, bool v, bool a) { WindowSkin = ws; importedTexture = it; windowWidth = w; prevWindowWidth = w; windowHeight = h; prevWindowHeight = h; windowTexture = new RenderTarget2D(g, windowWidth, windowHeight); currentWindow = windowTexture; visible = v; active = a; drawNew = true; topLeftRect = new Rectangle(0, 0, 32, 32); topRightRect = new Rectangle(32, 0, 32, 32); buttonRect = new Rectangle(64, 0, 32, 32); botLeftRect = new Rectangle(0, 64, 32, 32); botRightRect = new Rectangle(64, 64, 32, 32); } public void Update(GraphicsDevice g, Vector2 p, int width, int height) { prevWindowWidth = windowWidth; prevWindowHeight = windowHeight; pos = p; windowWidth = width; windowHeight = height; windowTexture = new RenderTarget2D(g, windowWidth+2, windowHeight+2); } public void Draw(SpriteBatch s, GraphicsDevice g) { s.Draw(currentWindow, pos, new Rectangle(0, 0, windowWidth, windowHeight), Color.White, 0, Vector2.Zero, 1.0f, SpriteEffects.None, 0); } public void DrawNewWindow(SpriteBatch s, GraphicsDevice g) { g.SetRenderTarget(windowTexture); g.Clear(Color.Transparent); s.Begin(); #region Draw Background for (int w = 3; w < (windowWidth); w += 32) { for (int h = 32; h < (windowHeight); h += 32) { s.Draw(WindowSkin, new Vector2(w, h), new Rectangle(32, 32, 32, 32), Color.White, 0, Vector2.Zero, 1.0f, SpriteEffects.None, 0); } } #endregion s.Draw(importedTexture, new Vector2(3, 32), new Rectangle(0, 0, importedTexture.Width, importedTexture.Height), Color.White, 0, Vector2.Zero, 1.0f, SpriteEffects.None, 0); #region Draw resizables for (int i = 32; i < (windowWidth - 64); i += 32) { s.Draw(WindowSkin, new Vector2(i, 0), new Rectangle(16, 0, 32, 32), Color.White, 0, Vector2.Zero, 1.0f, SpriteEffects.None, 0); } for (int i = 32; i < (windowWidth - 32); i += 32) { s.Draw(WindowSkin, new Vector2(i, windowHeight - 32), new Rectangle(32, 64, 32, 32), Color.White, 0, Vector2.Zero, 1.0f, SpriteEffects.None, 0); } for (int i = 64; i < (windowHeight - 32); i += 32) { s.Draw(WindowSkin, new Vector2(0, i), new Rectangle(0, 48, 32, 32), Color.White, 0, Vector2.Zero, 1.0f, SpriteEffects.None, 0); } for (int i = 64; i < (windowHeight - 32); i += 32) { s.Draw(WindowSkin, new Vector2(windowWidth - 32, i), new Rectangle(64, 48, 32, 32), Color.White, 0, Vector2.Zero, 1.0f, SpriteEffects.None, 0); } #endregion #region Draw Corners s.Draw(WindowSkin, new Vector2(0, 0), topLeftRect, Color.White, 0, Vector2.Zero, 1.0f, SpriteEffects.None, 0); s.Draw(WindowSkin, new Vector2(0, 32), new Rectangle(0, 32, 32, 32), Color.White, 0, Vector2.Zero, 1.0f, SpriteEffects.None, 0); s.Draw(WindowSkin, new Vector2(windowWidth - 64, 0), topRightRect, Color.White, 0, Vector2.Zero, 1.0f, SpriteEffects.None, 0); s.Draw(WindowSkin, new Vector2(windowWidth - 32, 32), new Rectangle(64, 32, 32, 32), Color.White, 0, Vector2.Zero, 1.0f, SpriteEffects.None, 0); s.Draw(WindowSkin, new Vector2(windowWidth - 32, 0), buttonRect, Color.White, 0, Vector2.Zero, 1.0f, SpriteEffects.None, 0); s.Draw(WindowSkin, new Vector2(0, windowHeight - 32), botLeftRect, Color.White, 0, Vector2.Zero, 1.0f, SpriteEffects.None, 0); s.Draw(WindowSkin, new Vector2(windowWidth - 32, windowHeight - 32), botRightRect, Color.White, 0, Vector2.Zero, 1.0f, SpriteEffects.None, 0); #endregion s.End(); currentWindow = windowTexture; } } } It's all nice and configured for my little windowskin texture, and such. the only problem is that it will get a little laggy, and then completely crash on me about a minute into running it. It throws an Out Of Memory Exception, but I don't know and can't find any other topic or post on this relating to spritebatch. Does anybody have any suggestions on how I can get this working and not take up much memory? I would think this as an easy, cost effective way of drawing a window. I'm just not sure how cut down on my draw calls, or get any of that memory back.

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  • ASP.NET MVC 2 Released

    - by Latest Microsoft Blogs
    I’m happy to announce that the final release of ASP.NET MVC 2 is now available for VS 2008/Visual Web Developer 2008 Express with ASP.NET 3.5.  You can download and install it from the following locations: Download ASP.NET MVC 2 using the Microsoft Read More......(read more)

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  • Now Customers Can Actually Locate Your Resources with URL Rewriter 2.0 RTW

    - by The Official Microsoft IIS Site
    Today, Microsoft announced the final release of IIS URL Rewriter 2.0 RTW . Now the first reason might be obvious why you would want to rewrite a URL – when you are at a cocktail party with loud music and tasty appetizers and a potential customer asks you where they can get more info on your snazzy new idea. And you proudly blurt out next to their ear over the roar of the bass, “Just go to h-t-t-p colon slash slash w-w-w dot my new idea dot com slash items dot a-s-p-x question mark cat ID equals new...(read more)

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  • Deeper Integration with phpBB

    - by The Official Microsoft IIS Site
    More good news on the Interoperability front: the new phpBB release is now available for installation from the Windows Web Application Gallery and Web Platform Installer (Web PI) for Windows, IIS and SQL Server. Version 3.0.7-PL1 of phpBB takes advantage of a number of features for PHP applications on the Microsoft Web Platform with Windows, IIS and SQL Server, including SQL Server Driver for PHP 1.1 , which provides key interoperability for PHP applications to use SQL Server or SQL Azure for data...(read more)

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  • IIS at TechEd Europe - Madrid - 26 June 2013

    - by The Official Microsoft IIS Site
    Don't miss the opportunity to hear Wade Hilmo, IIS' principal development lead, at Tech Ed Europe, 26 June 2013 in Madrid, Spain at the IFEMA – Feria de Madrid Convention Centre. Wade will be presenting the latest about IIS in Windows Server 2012 R2, bringing his special insight from his years leading the development team. The full details, including room & time are here: http://go.microsoft.com/fwlink/?LinkId=309913 Read More......(read more)

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  • IIS 7 Url Rewrite Rules for SEO and Security

    - by The Official Microsoft IIS Site
    Before IIS 7, if you wanted to do url rewriting with IIS 6 you had to use a 3rd party program such as ISAPI Rewrite by helicontech.com. This was a good program but it wasn’t native to IIS and there were limitations such as a site hosting more than 1 domain with different applications running. With IIS 7 url rewriting and redirecting has never been easier thanks to Microsoft’s Url Rewrite module. The rewriting is done by rules which are specified in the web.config under <system.webserver>...(read more)

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  • IIS SEO Toolkit Available in 10 Languages

    - by The Official Microsoft IIS Site
    A couple of months ago I blogged about the release of the v1.0.1 of the IIS Search Engine Optimization Toolkit . In March we released the localized versions of the SEO Toolkit so now it is available in 10 languages: English, Japanese, French, Russian, Korean, German, Spanish, Chinese Simplified, Italian and Chinese Traditional. Here are all the direct links to download it. Name Language Download URL IIS SEO Toolkit 32bit english http://download.microsoft.com/download/A/C/A/ACA8D740-A59D-4D25-A2D5...(read more)

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  • Tech Ed/BI Conference 2010: A Recovering Industry in a Recovering City

    - by andrewbrust
    I tried writing a post for this blog last night, while at the this year’s Microsoft Tech Ed and Business Intelligence conferences, in New Orleans. But I literally fell asleep while writing it.  That’s probably a sign that my readers might have done the same while reading it. Why the writer’s block? This was a very good show for me, but I think I was having trouble figuring out exactly why.  Now that I’m on the flight home, I’m starting to piece it together. One reason, for sure, was that I’ve spent years in both the developer and the BI worlds, and a show that combined the two was really enjoyable for me.  Typically, the subject matter, the attendees, the Microsoft execs and managers, and even the social circles have been separate.  This year’s Tech Ed facilitated a fusion of each of these previously segregated groups.  That was good for me as a speaker; for example, I facilitated a Birds of a Feather session on PowerPivot (Microsoft’s new self-service BI offering) which was well-attended, and by a large number of non-BI pros.  The fusion was good for me as an attendee too, as Microsoft BI, in the form of a new Pivot Viewer control, made it into the Day 1 keynote, demoed by Microsoft’s key BI champion, Amir Netz.  And it was good for me socially, as I was able to meet with peers in both camps, and at one location. Speaking of meeting with industry colleagues, I did a lot of that at this show.  Probably for the first time ever, I carefully scheduled and conducted a series of meetings with friends and business acquaintances in the developer tools, data visualization, utilities, publishing and training areas of the Microsoft ecosystem.  Beside the time efficiencies in conducting so many meetings, I discovered another benefit. I got a real handle on the tech industry’s economic health. The news here is good.  First of all, 2010 has been a great year for just about everyone I spoke to.  The mood is positive, energy is high, and people are working really hard.  This is, of course, refreshing to see, and it’s a huge relief.  Add to that the fact that this year’s Tech Ed was about 2.5 times larger in headcount than last year’s (based on numbers from unofficial, but reliable, sources), and the economic prognosis seems excellent.  But there’s more to it than that. Here’s the thing: everyone I talked to seems to be working, and succeeding, at changing their business models to adapt to changes in the industry.  Whether it’s the Internet’s impact on publishing and training, the increased importance of the developer audience in South Asia, the shift of affordable developer and business talent to unfamiliar locales abroad, or even lapses in Microsoft’s performance in the market, partner companies aren’t just rolling with the punches; they’re welcoming the changes and working them to their advantage.  No one seemed downtrodden, or even fatigued.  Even for businesses who have seen core revenue streams become commoditized, everyone seems to be changing their market strategy and winning.  Even Microsoft, of whom I have been critical recently, showed signs of successful hard work and playbook change, in the maturing of their cloud strategy, their commitment to it and their excitement around it.  And the embedded, managed, self-service BI strategy that Microsoft has been touting looks like it’s already being embraced by customers, even though PowerPivot, and other new Microsoft BI products, were released only recently. The collective optimism I have witnessed, and that I have felt, tells me good things about this industry and the economy.  The stock market had huge mood swings during my stay, and that may yet subdue the industry recovery I have seen this week.  Nonetheless, I am convinced that a strong foundation of hard work, innovative thinking and, if I may,  true renaissance is underlying this industry’s success. That kind of strength will generate a strong recovery, I am certain, whether now or once we’re past another round of choppy weather in the broader economy.  The fundamentals are good.

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  • Automate Log Parser to Find Your Data Faster

    - by The Official Microsoft IIS Site
    Microsoft’s Log Parser is a really powerful tool for searching log files. With just a few simple SQL commands you can pull more data than you ever imagined out of your logs. It can be used to read web site log files, csv files, and even Windows event logs. Log Parser isn’t intended to compete with stats products such as Webtrends Log Analyzer or SmarterStats by Smartertools.com which I feel is the best on the market. I primarily use Log Parser for troubleshooting problems with a site...(read more)

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  • SQL Server is now supported by phpBB!

    - by The Official Microsoft IIS Site
    Our team is really excited to announce the new release of phpBB 3.0.7-PL1 by the phpBB community that supports SQL Server, and one can download it from the Web Application Gallery for a very easy install!! But let’s step back for a moment and provide some background. Microsoft’s Interoperability team has been working with a few PHP projects to support SQL Server using our driver, phpBB was one of them. Although phpBB already had some support for SQL Server / Access, our 1.1 release driver offered...(read more)

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  • How to Schedule Backups with SQL Server Express

    - by The Official Microsoft IIS Site
    Microsoft’s SQL Server Express is a fantastic product for anyone needing a relational database on a limited budget. By limited budget I’m talking free. Yes SQL Server Express is free but it comes with a few limitations such as only utilizing 1 GB of RAM, databases are limited to 10 GB, and it does not include SQL Profiler. For low volume sites that do not need enterprise level capabilities, this is a compelling solution. Here is a complete SQL Server feature comparison of all the SQL Server...(read more)

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  • Facebook C# SDK submitted to the Outercurve Foundation

    - by The Official Microsoft IIS Site
    I am pleased to announce another open source milestone as we continue to deliver on our commitment to Interoperability: today, the Facebook C# SDK was submitted to the Outercurve Foundation’s Data, Languages, and Systems Interoperability gallery. This project is a set of libraries that enables developers of all Microsoft platforms, as well as Mono, to build applications that integrate with Facebook. The project contains core libraries for authentication and calling Facebook APIs. Additionally...(read more)

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  • Installing WordPress with WebMatrix 2

    - by The Official Microsoft IIS Site
    If you’re getting started with Windows web development or you just need a lightweight web development tool then check out Microsoft’s WebMatrix 2 . Creating, deploying, and maintaining, web sites has never been easier and considering it’s free you can’t beat it. What I like about WebMatrix is that it allows you to install 3rd party products such as blogs or forums from the App Gallery. I needed to create a new WordPress blog so that I could test a few things without impacting my production...(read more)

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  • WatiN screenshot saver

    - by Brian Schroer
    In addition to my automated unit, system and integration tests for ASP.NET projects, I like to give my customers something pretty that they can look at and visually see that the web site is behaving properly. I use the Gallio test runner to produce a pretty HTML report, and WatiN (Web Application Testing In .NET) to test the UI and create screenshots. I have a couple of issues with WatiN’s “CaptureWebPageToFile” method, though: It blew up the first (and only) time I tried it, possibly because… It scrolls down to capture the entire web page (I tried it on a very long page), and I usually don’t need that Also, sometimes I don’t need a picture of the whole browser window - I just want a picture of the element that I'm testing (for example, proving that a button has the correct caption). I wrote a WatiN screenshot saver helper class with these methods: SaveBrowserWindowScreenshot(Watin.Core.IE ie)  / SaveBrowserWindowScreenshot(Watin.Core.Element element) saves a screenshot of the browser window SaveBrowserWindowScreenshotWithHighlight(Watin.Core.Element element) saves a screenshot of the browser window, with the specified element scrolled into view and highlighted SaveElementScreenshot(Watin.Core.Element element) saves a picture of only the specified element The element highlighting improves on the built-in WatiN method (which just gives the element a yellow background, and makes the element pretty much unreadable when you have a light foreground color) by adding the ability to specify a HighlightCssClassName that points to a style in your site’s stylesheet. This code is specifically for testing with Internet Explorer (‘cause that’s what I have to test with at work), but you’re welcome to take it and do with it what you want… using System; using System.Drawing; using System.Drawing.Imaging; using System.IO; using System.Reflection; using System.Runtime.InteropServices; using System.Text; using System.Threading; using SHDocVw; using WatiN.Core; using mshtml; namespace BrianSchroer.TestHelpers { public static class WatinScreenshotSaver { public static void SaveBrowserWindowScreenshotWithHighlight (Element element, string screenshotName) { HighlightElement(element, true); SaveBrowserWindowScreenshot(element, screenshotName); HighlightElement(element, false); } public static void SaveBrowserWindowScreenshotWithHighlight(Element element) { HighlightElement(element, true); SaveBrowserWindowScreenshot(element); HighlightElement(element, false); } public static void SaveBrowserWindowScreenshot(Element element, string screenshotName) { SaveScreenshot(GetIe(element), screenshotName, SaveBitmapForCallbackArgs); } public static void SaveBrowserWindowScreenshot(Element element) { SaveScreenshot(GetIe(element), null, SaveBitmapForCallbackArgs); } public static void SaveBrowserWindowScreenshot(IE ie, string screenshotName) { SaveScreenshot(ie, screenshotName, SaveBitmapForCallbackArgs); } public static void SaveBrowserWindowScreenshot(IE ie) { SaveScreenshot(ie, null, SaveBitmapForCallbackArgs); } public static void SaveElementScreenshot(Element element, string screenshotName) { // TODO: Figure out how to get browser window "chrome" size and not have to go to full screen: var iex = (InternetExplorerClass) GetIe(element).InternetExplorer; bool fullScreen = iex.FullScreen; if (!fullScreen) iex.FullScreen = true; ScrollIntoView(element); SaveScreenshot(GetIe(element), screenshotName, args => SaveElementBitmapForCallbackArgs(element, args)); iex.FullScreen = fullScreen; } public static void SaveElementScreenshot(Element element) { SaveElementScreenshot(element, null); } private static void SaveScreenshot(IE browser, string screenshotName, Action<ScreenshotCallbackArgs> screenshotCallback) { string fileName = string.Format("{0:000}{1}{2}.jpg", ++_screenshotCount, (string.IsNullOrEmpty(screenshotName)) ? "" : " ", screenshotName); string path = Path.Combine(ScreenshotDirectoryName, fileName); Console.WriteLine(); // Gallio HTML-encodes the following display, but I have a utility program to // remove the "HTML===" and "===HTML" and un-encode the rest to show images in the Gallio report: Console.WriteLine("HTML===<div><b>{0}:</br></b><img src=\"{1}\" /></div>===HTML", screenshotName, new Uri(path).AbsoluteUri); MakeBrowserWindowTopmost(browser); try { var args = new ScreenshotCallbackArgs { InternetExplorerClass = (InternetExplorerClass)browser.InternetExplorer, ScreenshotPath = path }; Thread.Sleep(100); screenshotCallback(args); } catch (Exception ex) { Console.WriteLine(ex.Message); } } public static void HighlightElement(Element element, bool doHighlight) { if (!element.Exists) return; if (string.IsNullOrEmpty(HighlightCssClassName)) { element.Highlight(doHighlight); return; } string jsRef = element.GetJavascriptElementReference(); if (string.IsNullOrEmpty(jsRef)) return; var sb = new StringBuilder("try { "); sb.AppendFormat(" {0}.scrollIntoView(false);", jsRef); string format = (doHighlight) ? "{0}.className += ' {1}'" : "{0}.className = {0}.className.replace(' {1}', '')"; sb.AppendFormat(" " + format + ";", jsRef, HighlightCssClassName); sb.Append("} catch(e) {}"); string script = sb.ToString(); GetIe(element).RunScript(script); } public static void ScrollIntoView(Element element) { string jsRef = element.GetJavascriptElementReference(); if (string.IsNullOrEmpty(jsRef)) return; var sb = new StringBuilder("try { "); sb.AppendFormat(" {0}.scrollIntoView(false);", jsRef); sb.Append("} catch(e) {}"); string script = sb.ToString(); GetIe(element).RunScript(script); } public static void MakeBrowserWindowTopmost(IE ie) { ie.BringToFront(); SetWindowPos(ie.hWnd, HWND_TOPMOST, 0, 0, 0, 0, TOPMOST_FLAGS); } public static string HighlightCssClassName { get; set; } private static int _screenshotCount; private static string _screenshotDirectoryName; public static string ScreenshotDirectoryName { get { if (_screenshotDirectoryName == null) { var asm = Assembly.GetAssembly(typeof(WatinScreenshotSaver)); var uri = new Uri(asm.CodeBase); var fileInfo = new FileInfo(uri.LocalPath); string directoryName = fileInfo.DirectoryName; _screenshotDirectoryName = Path.Combine( directoryName, string.Format("Screenshots_{0:yyyyMMddHHmm}", DateTime.Now)); Console.WriteLine("Screenshot folder: {0}", _screenshotDirectoryName); Directory.CreateDirectory(_screenshotDirectoryName); } return _screenshotDirectoryName; } set { _screenshotDirectoryName = value; _screenshotCount = 0; } } [DllImport("user32.dll")] [return: MarshalAs(UnmanagedType.Bool)] private static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, uint uFlags); private static readonly IntPtr HWND_TOPMOST = new IntPtr(-1); private const UInt32 SWP_NOSIZE = 0x0001; private const UInt32 SWP_NOMOVE = 0x0002; private const UInt32 TOPMOST_FLAGS = SWP_NOMOVE | SWP_NOSIZE; private static IE GetIe(Element element) { if (element == null) return null; var container = element.DomContainer; while (container as IE == null) container = container.DomContainer; return (IE)container; } private static void SaveBitmapForCallbackArgs(ScreenshotCallbackArgs args) { InternetExplorerClass iex = args.InternetExplorerClass; SaveBitmap(args.ScreenshotPath, iex.Left, iex.Top, iex.Width, iex.Height); } private static void SaveElementBitmapForCallbackArgs(Element element, ScreenshotCallbackArgs args) { InternetExplorerClass iex = args.InternetExplorerClass; Rectangle bounds = GetElementBounds(element); SaveBitmap(args.ScreenshotPath, iex.Left + bounds.Left, iex.Top + bounds.Top, bounds.Width, bounds.Height); } /// <summary> /// This method is used instead of element.NativeElement.GetElementBounds because that /// method has a bug (http://sourceforge.net/tracker/?func=detail&aid=2994660&group_id=167632&atid=843727). /// </summary> private static Rectangle GetElementBounds(Element element) { var ieElem = element.NativeElement as WatiN.Core.Native.InternetExplorer.IEElement; IHTMLElement elem = ieElem.AsHtmlElement; int left = elem.offsetLeft; int top = elem.offsetTop; for (IHTMLElement parent = elem.offsetParent; parent != null; parent = parent.offsetParent) { left += parent.offsetLeft; top += parent.offsetTop; } return new Rectangle(left, top, elem.offsetWidth, elem.offsetHeight); } private static void SaveBitmap(string path, int left, int top, int width, int height) { using (var bitmap = new Bitmap(width, height)) { using (Graphics g = Graphics.FromImage(bitmap)) { g.CopyFromScreen( new Point(left, top), Point.Empty, new Size(width, height) ); } bitmap.Save(path, ImageFormat.Jpeg); } } private class ScreenshotCallbackArgs { public InternetExplorerClass InternetExplorerClass { get; set; } public string ScreenshotPath { get; set; } } } }

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  • C#: Optional Parameters - Pros and Pitfalls

    - by James Michael Hare
    When Microsoft rolled out Visual Studio 2010 with C# 4, I was very excited to learn how I could apply all the new features and enhancements to help make me and my team more productive developers. Default parameters have been around forever in C++, and were intentionally omitted in Java in favor of using overloading to satisfy that need as it was though that having too many default parameters could introduce code safety issues.  To some extent I can understand that move, as I’ve been bitten by default parameter pitfalls before, but at the same time I feel like Java threw out the baby with the bathwater in that move and I’m glad to see C# now has them. This post briefly discusses the pros and pitfalls of using default parameters.  I’m avoiding saying cons, because I really don’t believe using default parameters is a negative thing, I just think there are things you must watch for and guard against to avoid abuses that can cause code safety issues. Pro: Default Parameters Can Simplify Code Let’s start out with positives.  Consider how much cleaner it is to reduce all the overloads in methods or constructors that simply exist to give the semblance of optional parameters.  For example, we could have a Message class defined which allows for all possible initializations of a Message: 1: public class Message 2: { 3: // can either cascade these like this or duplicate the defaults (which can introduce risk) 4: public Message() 5: : this(string.Empty) 6: { 7: } 8:  9: public Message(string text) 10: : this(text, null) 11: { 12: } 13:  14: public Message(string text, IDictionary<string, string> properties) 15: : this(text, properties, -1) 16: { 17: } 18:  19: public Message(string text, IDictionary<string, string> properties, long timeToLive) 20: { 21: // ... 22: } 23: }   Now consider the same code with default parameters: 1: public class Message 2: { 3: // can either cascade these like this or duplicate the defaults (which can introduce risk) 4: public Message(string text = "", IDictionary<string, string> properties = null, long timeToLive = -1) 5: { 6: // ... 7: } 8: }   Much more clean and concise and no repetitive coding!  In addition, in the past if you wanted to be able to cleanly supply timeToLive and accept the default on text and properties above, you would need to either create another overload, or pass in the defaults explicitly.  With named parameters, though, we can do this easily: 1: var msg = new Message(timeToLive: 100);   Pro: Named Parameters can Improve Readability I must say one of my favorite things with the default parameters addition in C# is the named parameters.  It lets code be a lot easier to understand visually with no comments.  Think how many times you’ve run across a TimeSpan declaration with 4 arguments and wondered if they were passing in days/hours/minutes/seconds or hours/minutes/seconds/milliseconds.  A novice running through your code may wonder what it is.  Named arguments can help resolve the visual ambiguity: 1: // is this days/hours/minutes/seconds (no) or hours/minutes/seconds/milliseconds (yes) 2: var ts = new TimeSpan(1, 2, 3, 4); 3:  4: // this however is visually very explicit 5: var ts = new TimeSpan(days: 1, hours: 2, minutes: 3, seconds: 4);   Or think of the times you’ve run across something passing a Boolean literal and wondered what it was: 1: // what is false here? 2: var sub = CreateSubscriber(hostname, port, false); 3:  4: // aha! Much more visibly clear 5: var sub = CreateSubscriber(hostname, port, isBuffered: false);   Pitfall: Don't Insert new Default Parameters In Between Existing Defaults Now let’s consider a two potential pitfalls.  The first is really an abuse.  It’s not really a fault of the default parameters themselves, but a fault in the use of them.  Let’s consider that Message constructor again with defaults.  Let’s say you want to add a messagePriority to the message and you think this is more important than a timeToLive value, so you decide to put messagePriority before it in the default, this gives you: 1: public class Message 2: { 3: public Message(string text = "", IDictionary<string, string> properties = null, int priority = 5, long timeToLive = -1) 4: { 5: // ... 6: } 7: }   Oh boy have we set ourselves up for failure!  Why?  Think of all the code out there that could already be using the library that already specified the timeToLive, such as this possible call: 1: var msg = new Message(“An error occurred”, myProperties, 1000);   Before this specified a message with a TTL of 1000, now it specifies a message with a priority of 1000 and a time to live of -1 (infinite).  All of this with NO compiler errors or warnings. So the rule to take away is if you are adding new default parameters to a method that’s currently in use, make sure you add them to the end of the list or create a brand new method or overload. Pitfall: Beware of Default Parameters in Inheritance and Interface Implementation Now, the second potential pitfalls has to do with inheritance and interface implementation.  I’ll illustrate with a puzzle: 1: public interface ITag 2: { 3: void WriteTag(string tagName = "ITag"); 4: } 5:  6: public class BaseTag : ITag 7: { 8: public virtual void WriteTag(string tagName = "BaseTag") { Console.WriteLine(tagName); } 9: } 10:  11: public class SubTag : BaseTag 12: { 13: public override void WriteTag(string tagName = "SubTag") { Console.WriteLine(tagName); } 14: } 15:  16: public static class Program 17: { 18: public static void Main() 19: { 20: SubTag subTag = new SubTag(); 21: BaseTag subByBaseTag = subTag; 22: ITag subByInterfaceTag = subTag; 23:  24: // what happens here? 25: subTag.WriteTag(); 26: subByBaseTag.WriteTag(); 27: subByInterfaceTag.WriteTag(); 28: } 29: }   What happens?  Well, even though the object in each case is SubTag whose tag is “SubTag”, you will get: 1: SubTag 2: BaseTag 3: ITag   Why?  Because default parameter are resolved at compile time, not runtime!  This means that the default does not belong to the object being called, but by the reference type it’s being called through.  Since the SubTag instance is being called through an ITag reference, it will use the default specified in ITag. So the moral of the story here is to be very careful how you specify defaults in interfaces or inheritance hierarchies.  I would suggest avoiding repeating them, and instead concentrating on the layer of classes or interfaces you must likely expect your caller to be calling from. For example, if you have a messaging factory that returns an IMessage which can be either an MsmqMessage or JmsMessage, it only makes since to put the defaults at the IMessage level since chances are your user will be using the interface only. So let’s sum up.  In general, I really love default and named parameters in C# 4.0.  I think they’re a great tool to help make your code easier to read and maintain when used correctly. On the plus side, default parameters: Reduce redundant overloading for the sake of providing optional calling structures. Improve readability by being able to name an ambiguous argument. But remember to make sure you: Do not insert new default parameters in the middle of an existing set of default parameters, this may cause unpredictable behavior that may not necessarily throw a syntax error – add to end of list or create new method. Be extremely careful how you use default parameters in inheritance hierarchies and interfaces – choose the most appropriate level to add the defaults based on expected usage. Technorati Tags: C#,.NET,Software,Default Parameters

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  • Enabling Service Availability in WCF Services

    - by cibrax
    It is very important for the enterprise to know which services are operational at any given point. There are many factors that can affect the availability of the services, some of them are external like a database not responding or any dependant service not working. However, in some cases, you only want to know whether a service is up or down, so a simple heart-beat mechanism with “Ping” messages would do the trick. Unfortunately, WCF does not provide a built-in mechanism to support this functionality, and you probably don’t to implement a “Ping” operation in any service that you have out there. For solving this in a generic way, there is a WCF extensibility point that comes to help us, the “Operation Invokers”. In a nutshell, an operation invoker is the class responsible invoking the service method with a set of parameters and generate the output parameters with the return value. What I am going to do here is to implement a custom operation invoker that intercepts any call to the service, and detects whether a “Ping” header was attached to the message. If the “Ping” header is detected, the operation invoker returns a new header to tell the client that the service is alive, and the real operation execution is omitted. In that way, we have a simple heart beat mechanism based on the messages that include a "Ping” header, so the client application can determine at any point whether the service is up or down. My operation invoker wraps the default implementation attached by default to any operation by WCF. internal class PingOperationInvoker : IOperationInvoker { IOperationInvoker innerInvoker; object[] outputs = null; object returnValue = null; public const string PingHeaderName = "Ping"; public const string PingHeaderNamespace = "http://tellago.serviceModel"; public PingOperationInvoker(IOperationInvoker innerInvoker, OperationDescription description) { this.innerInvoker = innerInvoker; outputs = description.SyncMethod.GetParameters() .Where(p => p.IsOut) .Select(p => DefaultForType(p.ParameterType)).ToArray(); var returnValue = DefaultForType(description.SyncMethod.ReturnType); } private static object DefaultForType(Type targetType) { return targetType.IsValueType ? Activator.CreateInstance(targetType) : null; } public object Invoke(object instance, object[] inputs, out object[] outputs) { object returnValue; if (Invoke(out returnValue, out outputs)) { return returnValue; } else { return this.innerInvoker.Invoke(instance, inputs, out outputs); } } private bool Invoke(out object returnValue, out object[] outputs) { object untypedProperty = null; if (OperationContext.Current .IncomingMessageProperties.TryGetValue(HttpRequestMessageProperty.Name, out untypedProperty)) { var httpRequestProperty = untypedProperty as HttpRequestMessageProperty; if (httpRequestProperty != null) { if (httpRequestProperty.Headers[PingHeaderName] != null) { outputs = this.outputs; if (OperationContext.Current .IncomingMessageProperties.TryGetValue(HttpRequestMessageProperty.Name, out untypedProperty)) { var httpResponseProperty = untypedProperty as HttpResponseMessageProperty; httpResponseProperty.Headers.Add(PingHeaderName, "Ok"); } returnValue = this.returnValue; return true; } } } var headers = OperationContext.Current.IncomingMessageHeaders; if (headers.FindHeader(PingHeaderName, PingHeaderNamespace) > -1) { outputs = this.outputs; MessageHeader<string> header = new MessageHeader<string>("Ok"); var untyped = header.GetUntypedHeader(PingHeaderName, PingHeaderNamespace); OperationContext.Current.OutgoingMessageHeaders.Add(untyped); returnValue = this.returnValue; return true; } returnValue = null; outputs = null; return false; } } The implementation above looks for the “Ping” header either in the Http Request or the Soap message. The next step is to implement a behavior for attaching this operation invoker to the services we want to monitor. [AttributeUsage(AttributeTargets.Method | AttributeTargets.Class, AllowMultiple = false, Inherited = true)] public class PingBehavior : Attribute, IServiceBehavior, IOperationBehavior { public void AddBindingParameters(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase, Collection<ServiceEndpoint> endpoints, BindingParameterCollection bindingParameters) { } public void ApplyDispatchBehavior(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase) { } public void Validate(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase) { foreach (var endpoint in serviceDescription.Endpoints) { foreach (var operation in endpoint.Contract.Operations) { if (operation.Behaviors.Find<PingBehavior>() == null) operation.Behaviors.Add(this); } } } public void AddBindingParameters(OperationDescription operationDescription, BindingParameterCollection bindingParameters) { } public void ApplyClientBehavior(OperationDescription operationDescription, ClientOperation clientOperation) { } public void ApplyDispatchBehavior(OperationDescription operationDescription, DispatchOperation dispatchOperation) { dispatchOperation.Invoker = new PingOperationInvoker(dispatchOperation.Invoker, operationDescription); } public void Validate(OperationDescription operationDescription) { } } As an operation invoker can only be added in an “operation behavior”, a trick I learned in the past is that you can implement a service behavior as well and use the “Validate” method to inject it in all the operations, so the final configuration is much easier and cleaner. You only need to decorate the service with a simple attribute to enable the “Ping” functionality. [PingBehavior] public class HelloWorldService : IHelloWorld { public string Hello(string name) { return "Hello " + name; } } On the other hand, the client application needs to send a dummy message with a “Ping” header to detect whether the service is available or not. In order to simplify this task, I created a extension method in the WCF client channel to do this work. public static class ClientChannelExtensions { const string PingNamespace = "http://tellago.serviceModel"; const string PingName = "Ping"; public static bool IsAvailable<TChannel>(this IClientChannel channel, Action<TChannel> operation) { try { using (OperationContextScope scope = new OperationContextScope(channel)) { MessageHeader<string> header = new MessageHeader<string>(PingName); var untyped = header.GetUntypedHeader(PingName, PingNamespace); OperationContext.Current.OutgoingMessageHeaders.Add(untyped); try { operation((TChannel)channel); var headers = OperationContext.Current.IncomingMessageHeaders; if (headers.Any(h => h.Name == PingName && h.Namespace == PingNamespace)) { return true; } else { return false; } } catch (CommunicationException) { return false; } } } catch (Exception) { return false; } } } This extension method basically adds a “Ping” header to the request message, executes the operation passed as argument (Action<TChannel> operation), and looks for the corresponding “Ping” header in the response to see the results. The client application can use this extension with a single line of code, var client = new ServiceReference.HelloWorldClient(); var isAvailable = client.InnerChannel.IsAvailable<IHelloWorld>((c) => c.Hello(null)); The “isAvailable” variable will tell the client application whether the service is available or not. You can download the complete implementation from this location.    

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