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• FireFox 6 Super Slow? Cache Settings Corruption

  - by Rick Strahl

  For those of you that follow me on Twitter, you've probably seen some of my tweets regarding major performance problems I've seen with the install of FireFox 6.0. FireFox 6.0 was released a couple of weeks ago and is treated as a 'force feed' update for FireFox 5.0. I'm not sure what the deal is with this braindead versioning that Mozilla is doing with major version releases coming out, what now every other month? Seriously that's retarded especially given the limited number of new features these releases bring, and the upgrade pain for plug-ins that the major version release causes. Anyway, after the FireFox updater bugged me long enough I finally gave in last week and updated to FireFox 6. Immediately after install I noticed terrible performance. Everything was running at a snail's pace with Web pages loading slowly and most content actually slowly 'painting' the page. A typical sign of content downloading slowly. However these are pages that should be mostly cached on my system and even repeated accesses ran just as slow. Just for a reality check I ran the same sites in Chrome (blazing fast) and IE (fast enough :-)) but FireFox - dog on a stick. Why so slow Boss? While complaining lots of people recommended to ditch FireFox - use Chrome, yada yada yada. Yeah, Chrome is fast and getting better but I have a number of plug-ins that I use in FF that I can't easily give up. So I suffered and started looking around more closely at what was happening. The first thing I noticed when accessing pages was that I continually saw accesses to the Google CDN downloading jQuery and jQuery UI. UI especially is pretty heavy in size and currently I'm in a location with a fairly slow IP connection where large files are a bit of an issue. However, seeing the CDN urls pop up repeatedly raised a flag with me. That stuff should be caching and it looked like each and every hit was reloading these scripts and various images over and over again. Fired up FireBug and sure enough I saw something like this on a repeated hit to my blog: Those two highlights are jquery and the main CSS file for the site and both are being loaded fully and taking a while to load. However, since this page had been loaded before, these items should be cached and show 304 requests instead of the full HTTP requests returning 200 result codes. In short it looked like FireFox was not caching ANY content at all and constantly reloading all page resources. No wonder things were running dog slow. Once I realized what the problem was I took a look in the about:config settings and lo and behold a bunch of the cache settings were set to not cache: In my case ALL the main cache flags were set to false for some reason that I can't figure out.  It appears that after the FireFox 6 update these flags somehow mysteriously changed and performance took a nose dive. Switching the .enable flags back to true and resetting all the cache settings tote default reverted performance back to the way it's supposed to be: reasonably fast and snappy as soon as content is cached and accessed again  from cache. I try not to muck with the about:config settings much (other than turning off the IPV6 option) but when there are problems access to these features can be really nice. However, I treat this as a last resort so it took me quite some time before I started looking through ALL the settings. This takes a while, not knowing what I was looking for exactly. If Web load performance is slow it's a good idea to check the cache settings. I have no idea what hosed these settings for me - I certainly didn't explicitly set them in about:config and while in FireFox's Options dialog I didn't see any option that would affect global caching like this, so this remains a mystery to me. Anyway, I hope that this is helpful to some, in case some of you end up running into a similar issue.© Rick Strahl, West Wind Technologies, 2005-2011Posted in FireFox   Tweet (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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• An MCM exam, Rob? Really?

  - by Rob Farley

  I took the SQL 2008 MCM Knowledge exam while in Seattle for the PASS Summit ten days ago. I wasn’t planning to do it, but I got persuaded to try. I was meaning to write this post to explain myself before the result came out, but it seems I didn’t get typing quickly enough. Those of you who know me will know I’m a big fan of certification, to a point. I’ve been involved with Microsoft Learning to help create exams. I’ve kept my certifications current since I first took an exam back in 1998, sitting many in beta, across quite a variety of topics. I’ve probably become quite good at them – I know I’ve definitely passed some that I really should’ve failed. I’ve also written that I don’t think exams are worth studying for. (That’s probably not entirely true, but it depends on your motivation. If you’re doing learning, I would encourage you to focus on what you need to know to do your job better. That will help you pass an exam – but the two skills are very different. I can coach someone on how to pass an exam, but that’s a different kind of teaching when compared to coaching someone about how to do a job. For example, the real world includes a lot of “it depends”, where you develop a feel for what the influencing factors might be. In an exam, its better to be able to know some of the “Don’t use this technology if XYZ is true” concepts better.) As for the Microsoft Certified Master certification… I’m not opposed to the idea of having the MCM (or in the future, MCSM) cert. But the barrier to entry feels quite high for me. When it was first introduced, the nearest testing centres to me were in Kuala Lumpur and Manila. Now there’s one in Perth, but that’s still a big effort. I know there are options in the US – such as one about an hour’s drive away from downtown Seattle, but it all just seems too hard. Plus, these exams are more expensive, and all up – I wasn’t sure I wanted to try them, particularly with the fact that I don’t like to study. I used to study for exams. It would drive my wife crazy. I’d have some exam scheduled for some time in the future (like the time I had two booked for two consecutive days at TechEd Australia 2005), and I’d make sure I was ready. Every waking moment would be spent pouring over exam material, and it wasn’t healthy. I got shaken out of that, though, when I ended up taking four exams in those two days in 2005 and passed them all. I also worked out that if I had a Second Shot available, then failing wasn’t a bad thing at all. Even without Second Shot, I’m much more okay about failing. But even just trying an MCM exam is a big effort. I wouldn’t want to fail one of them. Plus there’s the illusion to maintain. People have told me for a long time that I should just take the MCM exams – that I’d pass no problem. I’ve never been so sure. It was almost becoming a pride-point. Perhaps I should fail just to demonstrate that I can fail these things. Anyway – boB Taylor (@sqlboBT) persuaded me to try the SQL 2008 MCM Knowledge exam at the PASS Summit. They set up a testing centre in one of the room there, so it wasn’t out of my way at all. I had to squeeze it in between other commitments, and I certainly didn’t have time to even see what was on the syllabus, let alone study. In fact, I was so exhausted from the week that I fell asleep at least once (just for a moment though) during the actual exam. Perhaps the questions need more jokes, I’m not sure. I knew if I failed, then I might disappoint some people, but that I wouldn’t’ve spent a great deal of effort in trying to pass. On the other hand, if I did pass I’d then be under pressure to investigate the MCM Lab exam, which can be taken remotely (therefore, a much smaller amount of effort to make happen). In some ways, passing could end up just putting a bunch more pressure on me. Oh, and I did.

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• Is Information Technology really Engineering?

  - by RPK

  While travelling I met a mathematician who was sitting near me. In a discussion he said: "...there is nothing like engineering in IT or rather programming". A true engineering is what Architecture is, what Electrical and Mechanical is. It made me think and I was puzzled. A percent of my brain agreed also because in Indian Army, there is no subject like Computer Engineering in the Engineering Corps. They don't consider programming as engineering. This is what I heard few years back, I don't know what Indian Army thinks now. What are your views?

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• Implementing an Interceptor Using NHibernate’s Built In Dynamic Proxy Generator

  - by Ricardo Peres

  NHibernate 3.2 came with an included proxy generator, which means there is no longer the need – or the possibility, for that matter – to choose Castle DynamicProxy, LinFu or Spring. This is actually a good thing, because it means one less assembly to deploy. Apparently, this generator was based, at least partially, on LinFu. As there are not many tutorials out there demonstrating it’s usage, here’s one, for demonstrating one of the most requested features: implementing INotifyPropertyChanged. This interceptor, of course, will still feature all of NHibernate’s functionalities that you are used to, such as lazy loading, and such. We will start by implementing an NHibernate interceptor, by inheriting from the base class NHibernate.EmptyInterceptor. This class does not do anything by itself, but it allows us to plug in behavior by overriding some of its methods, in this case, Instantiate: 1: public class NotifyPropertyChangedInterceptor : EmptyInterceptor 2: { 3: private ISession session = null; 4:  5: private static readonly ProxyFactory factory = new ProxyFactory(); 6:  7: public override void SetSession(ISession session) 8: { 9: this.session = session; 10: base.SetSession(session); 11: } 12:  13: public override Object Instantiate(String clazz, EntityMode entityMode, Object id) 14: { 15: Type entityType = Type.GetType(clazz); 16: IProxy proxy = factory.CreateProxy(entityType, new _NotifyPropertyChangedInterceptor(), typeof(INotifyPropertyChanged)) as IProxy; 17: 18: _NotifyPropertyChangedInterceptor interceptor = proxy.Interceptor as _NotifyPropertyChangedInterceptor; 19: interceptor.Proxy = this.session.SessionFactory.GetClassMetadata(entityType).Instantiate(id, entityMode); 20:  21: this.session.SessionFactory.GetClassMetadata(entityType).SetIdentifier(proxy, id, entityMode); 22:  23: return (proxy); 24: } 25: } Then we need a class that implements the NHibernate dynamic proxy behavior, let’s place it inside our interceptor, because it will only need to be used there: 1: class _NotifyPropertyChangedInterceptor : NHibernate.Proxy.DynamicProxy.IInterceptor 2: { 3: private PropertyChangedEventHandler changed = delegate { }; 4:  5: public Object Proxy 6: { 7: get; 8: set;} 9:  10: #region IInterceptor Members 11:  12: public Object Intercept(InvocationInfo info) 13: { 14: Boolean isSetter = info.TargetMethod.Name.StartsWith("set_") == true; 15: Object result = null; 16:  17: if (info.TargetMethod.Name == "add_PropertyChanged") 18: { 19: PropertyChangedEventHandler propertyChangedEventHandler = info.Arguments[0] as PropertyChangedEventHandler; 20: this.changed += propertyChangedEventHandler; 21: } 22: else if (info.TargetMethod.Name == "remove_PropertyChanged") 23: { 24: PropertyChangedEventHandler propertyChangedEventHandler = info.Arguments[0] as PropertyChangedEventHandler; 25: this.changed -= propertyChangedEventHandler; 26: } 27: else 28: { 29: result = info.TargetMethod.Invoke(this.Proxy, info.Arguments); 30: } 31:  32: if (isSetter == true) 33: { 34: String propertyName = info.TargetMethod.Name.Substring("set_".Length); 35: this.changed(this.Proxy, new PropertyChangedEventArgs(propertyName)); 36: } 37:  38: return (result); 39: } 40:  41: #endregion 42: } What this does for every interceptable method (those who are either virtual or from the INotifyPropertyChanged) is: For methods that came from the INotifyPropertyChanged interface, add_PropertyChanged and remove_PropertyChanged (yes, events are methods ), we add an implementation that adds or removes the event handlers to the delegate which we declared as changed; For all the others, we direct them to the place where they are actually implemented, which is the Proxy field; If the call is setting a property, it fires afterwards the PropertyChanged event. In order to use this, we need to add the interceptor to the Configuration before building the ISessionFactory: 1: using (ISessionFactory factory = cfg.SetInterceptor(new NotifyPropertyChangedInterceptor()).BuildSessionFactory()) 2: { 3: using (ISession session = factory.OpenSession()) 4: using (ITransaction tx = session.BeginTransaction()) 5: { 6: Customer customer = session.Get<Customer>(100); //some id 7: INotifyPropertyChanged inpc = customer as INotifyPropertyChanged; 8: inpc.PropertyChanged += delegate(Object sender, PropertyChangedEventArgs e) 9: { 10: //fired when a property changes 11: }; 12: customer.Address = "some other address"; //will raise PropertyChanged 13: customer.RecentOrders.ToList(); //will trigger the lazy loading 14: } 15: } Any problems, questions, do drop me a line!

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• Killing Stuck Child JVM's

  - by ACShorten

  Note: This facility only applies to Oracle Utilities Application Framework products using COBOL. In some situations, the Child JVM's may spin. This causes multiple startup/shutdown Child JVM messages to be displayed and recursive child JVM's to be initiated and shunned. If the following: Unable to establish connection on port …. after waiting .. seconds.The issue can be caused intermittently by CPU spins in connection to the creation of new processes, specifically Child JVMs. Recursive (or double) invocation of the System.exit call in the remote JVM may be caused by a Process.destroy call that the parent JVM always issues when shunning a JVM. The issue may happen when the thread in the parent JVM that is responsible for the recycling gets stuck and it affects all child JVMs. If this issue occurs at your site then there are a number of options to address the issue: Configure an Operating System level kill command to force the Child JVM to be shunned when it becomes stuck. Configure a Process.destroy command to be used if the kill command is not configured or desired. Specify a time tolerance to detect stuck threads before issuing the Process.destroy or kill commands. Note: This facility is also used when the Parent JVM is also shutdown to ensure no zombie Child JVM's exit. The following additional settings must be added to the spl.properties for the Business Application Server to use this facility: spl.runtime.cobol.remote.kill.command – Specify the command to kill the Child JVM process. This can be a command or specify a script to execute to provide additional information. The kill.command property can accept two arguments, {pid} and {jvmNumber}, in the specified string. The arguments must be enclosed in curly braces as shown here. Note: The PID will be appended to the killcmd string, unless the {pid} and {jvmNumber} arguments are specified. The jvmNumber can be useful if passed to a script for logging purposes. Note: If a script is used it must be in the path and be executable by the OS user running the system. spl.runtime.cobol.remote.destroy.enabled – Specify whether to use the Process.destroy command instead of the kill command. Specify true or false. Default value is false. Note: Unless otherwise required, it is recommended to use the kill command option if shunning JVM's is an issue. There this value can remain its default value, false, unless otherwise required. spl.runtime.cobol.remote.kill.delaysecs – Specify the number of seconds to wait for the Child JVM to terminate naturally before issuing the Process.destroy or kill commands. Default is 10 seconds. For example: spl.runtime.cobol.remote.kill.command=kill -9 {pid} {jvmNumber}spl.runtime.cobol.remote.destroy.enabled=falsespl.runtime.cobol.remote.kill.delaysecs=10 When a Child JVM is to be recycled, these properties are inspected and the spl.runtime.cobol.remote.kill.command, executed if provided. This is done after waiting for spl.runtime.cobol.remote.kill.delaysecs seconds to give the JVM time to shut itself down. The spl.runtime.cobol.remote.destroy.enabled property must be set to true AND the spl.runtime.cobol.remote.kill.command omitted for the original Process.destroy command to be used on the process. Note: By default the spl.runtime.cobol.remote.destroy enabled is set to false and is therefore disabled. If neither spl.runtime.cobol.remote.kill.command nor spl.runtime.cobol.remote.destroy.enabled is specified, child JVMs will not beforcibly killed. They will be left to shut themselves down (which may lead to orphan JVMs). If both are specified, the spl.runtime.cobol.remote.kill.command is preferred and spl.runtime.cobol.remote.destroy.enabled defaulted to false.It is recommended to invoke a script to issue the direct kill command instead of directly using the kill -9 commands.For example, the following sample script ensures that the process Id is an active cobjrun process before issuing the kill command: forcequit.sh #!/bin/shTHETIME=`date +"%Y-%m-%d %H:%M:%S"`if [ "$1" = "" ]then  echo "$THETIME: Process Id is required" >>$SPLSYSTEMLOGS/forcequit.log  exit 1fijavaexec=cobjrunps e $1 | grep -c $javaexecif [ $? = 0 ]then  echo "$THETIME: Process $1 is an active $javaexec process -- issuing kill-9 $1" >>$SPLSYSTEMLOGS/forcequit.log  kill -9 $1exit 0else  echo "$THETIME: Process id $1 is not a $javaexec process or not active --  kill will not be issued" >>$SPLSYSTEMLOGS/forcequit.logexit 1fi This script's name would then be specified as the value for the spl.runtime.cobol.remote.kill.command property, for example: spl.runtime.cobol.remote.kill.command=forcequit.sh The forcequit script does not have any explicit parameters but pid is passed automatically. To use the jvmNumber parameter it must explicitly specified in the command. For example, to call script forcequit.sh and pass it the pid and the child JVM number, specify it as follows: spl.runtime.cobol.remote.kill.command=forcequit.sh {pid} {jvmNumber} The script can then use the JVM number for logging purposes or to further ensure that the correct pid is being killed.If the arguments are omitted, the pid is automatically appended to the spl.runtime.cobol.remote.kill.command string. To use this facility the following patches must be installed: Patch 13719584 for Oracle Utilities Application Framework V2.1, Patches 13684595 and 13634933 for Oracle Utilities Application Framework V2.2 Group Fix 4 (as Patch 13640668) for Oracle Utilities Application Framework V4.1.

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• Disabling depth write trashes the frame buffer on some GPUs

  - by EboMike

  I sometimes disable depth buffer writing via glDepthMask(GL_FALSE) during the alpha rendering of a frame. That works perfectly fine on some GPUs (like the Motorola Droid's PowerVR), but on the HTC EVO with the Adreno GPU for example, I end up with the frame buffer being complete garbage (I see traces of the meshes I rendered somewhere, but the entire screen is mostly trashed). If I force glDepthMask to be true the entire time, everything works fine. I need glDepthMask to be off during parts of the alpha rendering. What can cause the framebuffer to get destroyed by turning the depth writing off? I do clear the depth buffer initially, and the majority of the screen has pixels rendered with depth writing turned on first before I do additional drawing with it turned off.

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• Does programming knowledge have a half-life?

  - by Gary Rowe

  In answering this question, I asserted that programming knowledge has a half-life of about 18 months. In physics, we have radioactive decay which is the process by which a radioactive element transforms into something less energetic. The half-life is the measure of how long it takes for this process to result in only half of the material to remain. A parallel concept might be that over time our programming knowledge ceases to be the current idiom and eventually becomes irrelevant. Noting that a half-life is asymptotic (so some knowledge will always be relevant), what are your thoughts on this? Is 18 months a good estimate? Is it even the case? Does it apply to design patterns, but over a longer period? What are the inherent advantages/disadvantages of this half-life? Update Just found this question which covers the material fairly well: "Half of everything you know will be obsolete in 18-24 months" = ( True, or False? )

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• Does Ubuntu generally post timely security updates?

  - by Jo Liss

  Concrete issue: The Oneiric nginx package is at version 1.0.5-1, released in July 2011 according to the changelog. The recent memory-disclosure vulnerability (advisory page, CVE-2012-1180, DSA-2434-1) isn't fixed in 1.0.5-1. If I'm not misreading the Ubuntu CVE page, all Ubuntu versions seem to ship a vulnerable nginx. Is this true? If so: I though there was a security team at Canonical that's actively working on issues like this, so I expected to get a security update within a short timeframe (hours or days) through apt-get update. Is this expectation -- that keeping my packages up-to-date is enough to stop my server from having known vulnerabilities -- generally wrong? If so: What should I do to keep it secure? Reading the Ubuntu security notices wouldn't have helped in this case, as the nginx vulnerability was never posted there.

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• C# window application : How to validate mobile no.

  - by SAMIR BHOGAYTA

  //First : Simple Method private void textBox1_KeyPress(object sender, KeyPressEventArgs e) { if (char.IsDigit(e.KeyChar) == true) { if (textBox1.Text.Length 10) { MessageBox.Show("Invalid Indian Mobile Number !!"); txtPhone.Focus(); } } //With the help of JavaScript function phone_validate(phone) { var phoneReg = ^((\+)?(\d{2}[-]))?(\d{10}){1}?$; if(phoneReg.test(phone) == false) { alert("Phone number is not yet valid."); } else { alert("You have entered a valid phone number!"); } }

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• Making an Ubuntu installation disc UEFI bootable

  - by skytreader

  I'm trying to install Ubuntu 12.04 on a machine with UEFI (Windows 8). Following Rod Books, I managed to get my system to boot using rEFInd. However rEFInd does not offer me any options to boot from my Ubuntu installer disc. Another thing...after following Rod Books' instructions, my machine greeted me with something along the lines of "The bootloader is not trusted" (my usage of the term "bootloader" is possibly wrong; I'm not well-acquainted with these terms) I got to work around this by setting up some passwords in the BIOS and putting the renamed .efi of rEFInd to the trusted list. While in this screen, it showed me the drives with a possible .efi (among them, the drive S in Rod Books' guide) and one of the drives it showed was my optical drive with an Ubuntu installer. I tried browsing for an .efi in the Ubuntu installer but found none. True enough, at Windows, I searched the drive for an .efi but found none. So how do I make my Ubuntu installer UEFI bootable?

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• [Windows 8] Application bar popup button

  - by Benjamin Roux

  Here is a small control to create an application bar button which will display a content in a popup when the button is clicked. Visually it gives this So how to create this? First you have to use the AppBarPopupButton control below.   namespace Indeed.Controls { public class AppBarPopupButton : Button { public FrameworkElement PopupContent { get { return (FrameworkElement)GetValue(PopupContentProperty); } set { SetValue(PopupContentProperty, value); } } public static readonly DependencyProperty PopupContentProperty = DependencyProperty.Register("PopupContent", typeof(FrameworkElement), typeof(AppBarPopupButton), new PropertyMetadata(null, (o, e) => (o as AppBarPopupButton).CreatePopup())); private Popup popup; private SerialDisposable sizeChanged = new SerialDisposable(); protected override void OnTapped(Windows.UI.Xaml.Input.TappedRoutedEventArgs e) { base.OnTapped(e); if (popup != null) { var transform = this.TransformToVisual(Window.Current.Content); var offset = transform.TransformPoint(default(Point)); sizeChanged.Disposable = PopupContent.ObserveSizeChanged().Do(_ => popup.VerticalOffset = offset.Y - (PopupContent.ActualHeight + 20)).Subscribe(); popup.HorizontalOffset = offset.X + 24; popup.DataContext = this.DataContext; popup.IsOpen = true; } } private void CreatePopup() { popup = new Popup { IsLightDismissEnabled = true }; popup.Closed += (o, e) => this.GetParentOfType<AppBar>().IsOpen = false; popup.ChildTransitions = new Windows.UI.Xaml.Media.Animation.TransitionCollection(); popup.ChildTransitions.Add(new Windows.UI.Xaml.Media.Animation.PopupThemeTransition()); var container = new Grid(); container.Children.Add(PopupContent); popup.Child = container; } } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The ObserveSizeChanged method is just an extension method which observe the SizeChanged event (using Reactive Extensions - Rx-Metro package in Nuget). If you’re not familiar with Rx, you can replace this line (and the SerialDisposable stuff) by a simple subscription to the SizeChanged event (using +=) but don’t forget to unsubscribe to it ! public static IObservable<Unit> ObserveSizeChanged(this FrameworkElement element) { return Observable.FromEventPattern<SizeChangedEventHandler, SizeChangedEventArgs>( o => element.SizeChanged += o, o => element.SizeChanged -= o) .Select(_ => Unit.Default); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The GetParentOfType extension method just retrieve the first parent of type (it’s a common extension method that every Windows 8 developer should have created !). You can of course tweak to control (for example if you want to center the content to the button or anything else) to fit your needs. How to use this control? It’s very simple, in an AppBar control just add it and define the PopupContent property. <ic:AppBarPopupButton Style="{StaticResource RefreshAppBarButtonStyle}" HorizontalAlignment="Left"> <ic:AppBarPopupButton.PopupContent> <Grid> [...] </Grid> </ic:AppBarPopupButton.PopupContent> </ic:AppBarPopupButton> .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } When the button is clicked the popup is displayed. When the popup is closed, the app bar is closed too. I hope this will help you !

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• GPL: does one line of GPLed code make program a "derived work"

  - by SigTerm

  I've recently run into some argument with a person that claims to be a lawyer (I have my suspicions about this not being completely true, though). As far as I know, copying even one line of code from GPLed program into proprietary body of code requires you to release the whole thing under GPL, if you ever decide to publish the software and make it available to the public. The person in question claims that it is "absurd" (I know it is, but AFAIK that's how GPL works), it is "redefining the copyright", "GPL has no power to do that", and claiming that "one line of GPLed code makes you release the whole thing under GPL" is absurd. That contradicts the GPL FAQ. Can somebody clarify the situation? Am I right in assumption that copying even smallest subroutine from GPL program into your code automatically makes your program a "derived work" which means you are obliged to release it under GPL license if you publish it?

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• Flood fill algorithm for Game of Go

  - by Jackson Borghi

  I'm having a hell of a time trying to figure out how to make captured stones disappear. I've read everywhere that I should use the flood fill algorithm, but I haven't had any luck with that so far. Any help would be amazing! Here is my code: package Go; import static java.lang.Math.*; import static stdlib.StdDraw.*; import java.awt.Color; public class Go2 { public static Color opposite(Color player) { if (player == WHITE) { return BLACK; } return WHITE; } public static void drawGame(Color[][] board) { Color[][][] unit = new Color[400][19][19]; for (int h = 0; h < 400; h++) { for (int x = 0; x < 19; x++) { for (int y = 0; y < 19; y++) { unit[h][x][y] = YELLOW; } } } setXscale(0, 19); setYscale(0, 19); clear(YELLOW); setPenColor(BLACK); line(0, 0, 0, 19); line(19, 19, 19, 0); line(0, 19, 19, 19); line(0, 0, 19, 0); for (double i = 0; i < 19; i++) { line(0.0, i, 19, i); line(i, 0.0, i, 19); } for (int x = 0; x < 19; x++) { for (int y = 0; y < 19; y++) { if (board[x][y] != YELLOW) { setPenColor(board[x][y]); filledCircle(x, y, 0.47); setPenColor(GRAY); circle(x, y, 0.47); } } } int h = 0; } public static void main(String[] args) { int px; int py; Color[][] temp = new Color[19][19]; Color[][] board = new Color[19][19]; Color player = WHITE; for (int i = 0; i < 19; i++) { for (int h = 0; h < 19; h++) { board[i][h] = YELLOW; temp[i][h] = YELLOW; } } while (true) { drawGame(board); while (!mousePressed()) { } px = (int) round(mouseX()); py = (int) round(mouseY()); board[px][py] = player; while (mousePressed()) { } floodFill(px, py, player, board, temp); System.out.print("XXXXX = "+ temp[px][py]); if (checkTemp(temp, board, px, py)) { for (int x = 0; x < 19; x++) { for (int y = 0; y < 19; y++) { if (temp[x][y] == GRAY) { board[x][y] = YELLOW; } } } } player = opposite(player); } } private static boolean checkTemp(Color[][] temp, Color[][] board, int x, int y) { if (x < 19 && x > -1 && y < 19 && y > -1) { if (temp[x + 1][y] == YELLOW || temp[x - 1][y] == YELLOW || temp[x][y - 1] == YELLOW || temp[x][y + 1] == YELLOW) { return false; } } if (x == 18) { if (temp[x - 1][y] == YELLOW || temp[x][y - 1] == YELLOW || temp[x][y + 1] == YELLOW) { return false; } } if (y == 18) { if (temp[x + 1][y] == YELLOW || temp[x - 1][y] == YELLOW || temp[x][y - 1] == YELLOW) { return false; } } if (y == 0) { if (temp[x + 1][y] == YELLOW || temp[x - 1][y] == YELLOW || temp[x][y + 1] == YELLOW) { return false; } } if (x == 0) { if (temp[x + 1][y] == YELLOW || temp[x][y - 1] == YELLOW || temp[x][y + 1] == YELLOW) { return false; } } else { if (x < 19) { if (temp[x + 1][y] == GRAY) { checkTemp(temp, board, x + 1, y); } } if (x >= 0) { if (temp[x - 1][y] == GRAY) { checkTemp(temp, board, x - 1, y); } } if (y < 19) { if (temp[x][y + 1] == GRAY) { checkTemp(temp, board, x, y + 1); } } if (y >= 0) { if (temp[x][y - 1] == GRAY) { checkTemp(temp, board, x, y - 1); } } } return true; } private static void floodFill(int x, int y, Color player, Color[][] board, Color[][] temp) { if (board[x][y] != player) { return; } else { temp[x][y] = GRAY; System.out.println("x = " + x + " y = " + y); if (x < 19) { floodFill(x + 1, y, player, board, temp); } if (x >= 0) { floodFill(x - 1, y, player, board, temp); } if (y < 19) { floodFill(x, y + 1, player, board, temp); } if (y >= 0) { floodFill(x, y - 1, player, board, temp); } } } }

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• Arithmetic Coding Questions

  - by Xophmeister

  I have been reading up on arithmetic coding and, while I understand how it works, all the guides and instructions I've read start with something like: Set up your intervals based upon the frequency of symbols in your data; i.e., more likely symbols get proportionally larger intervals. My main query is, once I have encoded my data, presumably I also need to include this statistical model with the encoding, otherwise the compressed data can't be decoded. Is that correct? I don't see this mentioned anywhere -- the most I've seen is that you need to include the number of iterations (i.e., encoded symbols) -- but unless I'm missing something, this also seems necessary to me. If this is true, that will obviously add an overhead to the final output. At what point does this outweigh the benefits of compression (e.g., say if I'm trying to compress just a few thousand bits)? Will the choice of symbol size also make a significant difference (e.g., if I'm looking at 2-bit words, rather than full octets/whatever)?

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• How to hire a web-programmer : for non-programmer

  - by 0Complex

  I am a non-programmer that has used the services of : freelancer, odesk, etc I've tried asking for what i need but, I can't find anyone who can show me any type of example similar to what I request in the specs for the web-programming. They have front ends and back ends, but they don't fulfill true "live" website requirements. "live" as to be ready to support traffic, keys in hand, can be updated constantly by me, ... How do I figure how to evaluate a programmer ? How do I bid the appropriate price for the services ?

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• Allowing Access to HttpContext in WCF REST Services

  - by Rick Strahl

  If you’re building WCF REST Services you may find that WCF’s OperationContext, which provides some amount of access to Http headers on inbound and outbound messages, is pretty limited in that it doesn’t provide access to everything and sometimes in a not so convenient manner. For example accessing query string parameters explicitly is pretty painful: [OperationContract] [WebGet] public string HelloWorld() { var properties = OperationContext.Current.IncomingMessageProperties; var property = properties[HttpRequestMessageProperty.Name] as HttpRequestMessageProperty; string queryString = property.QueryString; var name = StringUtils.GetUrlEncodedKey(queryString,"Name"); return "Hello World " + name; } And that doesn’t account for the logic in GetUrlEncodedKey to retrieve the querystring value. It’s a heck of a lot easier to just do this: [OperationContract] [WebGet] public string HelloWorld() { var name = HttpContext.Current.Request.QueryString["Name"] ?? string.Empty; return "Hello World " + name; } Ok, so if you follow the REST guidelines for WCF REST you shouldn’t have to rely on reading query string parameters manually but instead rely on routing logic, but you know what: WCF REST is a PITA anyway and anything to make things a little easier is welcome. To enable the second scenario there are a couple of steps that you have to take on your service implementation and the configuration file. Add aspNetCompatibiltyEnabled in web.config Fist you need to configure the hosting environment to support ASP.NET when running WCF Service requests. This ensures that the ASP.NET pipeline is fired up and configured for every incoming request. <system.serviceModel>     <serviceHostingEnvironment aspNetCompatibilityEnabled="true" multipleSiteBindingsEnabled="true" /> </system.serviceModel> Markup your Service Implementation with AspNetCompatibilityRequirements Attribute Next you have to mark up the Service Implementation – not the contract if you’re using a separate interface!!! – with the AspNetCompatibilityRequirements attribute: [ServiceContract(Namespace = "RateTestService")] [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)] public class RestRateTestProxyService Typically you’ll want to use Allowed as the preferred option. The other options are NotAllowed and Required. Allowed will let the service run if the web.config attribute is not set. Required has to have it set. All these settings determine whether an ASP.NET host AppDomain is used for requests. Once Allowed or Required has been set on the implemented class you can make use of the ASP.NET HttpContext object. When I allow for ASP.NET compatibility in my WCF services I typically add a property that exposes the Context and Request objects a little more conveniently: public HttpContext Context { get { return HttpContext.Current; } } public HttpRequest Request { get { return HttpContext.Current.Request; } } While you can also access the Response object and write raw data to it and manipulate headers THAT is probably not such a good idea as both your code and WCF will end up writing into the output stream. However it might be useful in some situations where you need to take over output generation completely and return something completely custom. Remember though that WCF REST DOES actually support that as well with Stream responses that essentially allow you to return any kind of data to the client so using Response should really never be necessary. Should you or shouldn’t you? WCF purists will tell you never to muck with the platform specific features or the underlying protocol, and if you can avoid it you definitely should avoid it. Querystring management in particular can be handled largely with Url Routing, but there are exceptions of course. Try to use what WCF natively provides – if possible as it makes the code more portable. For example, if you do enable ASP.NET Compatibility you won’t be able to self host a WCF REST service. At the same time realize that especially in WCF REST there are number of big holes or access to some features are a royal pain and so it’s not unreasonable to access the HttpContext directly especially if it’s only for read-only access. Since everything in REST works of URLS and the HTTP protocol more control and easier access to HTTP features is a key requirement to building flexible services. It looks like vNext of the WCF REST stuff will feature many improvements along these lines with much deeper native HTTP support that is often so useful in REST applications along with much more extensibility that allows for customization of the inputs and outputs as data goes through the request pipeline. I’m looking forward to this stuff as WCF REST as it exists today still is a royal pain (in fact I’m struggling with a mysterious version conflict/crashing error on my machine that I have not been able to resolve – grrrr…).© Rick Strahl, West Wind Technologies, 2005-2011Posted in ASP.NET  AJAX  WCF  

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• How do I enable WebGL sites with Firefox 4 Beta?

  - by Greg Grossmeier

  I am using Firefox 4.0b12 from the Mozilla Team's "Firefox Next" PPA. My about:config has webgl.enabled_for_all_sites set to true as most guides recommend that and also say that is all that is needed. It doesn't work for me. The main Mozilla Demos page ("Web O' Wonder") gives me: Unfortunately, while your browser supports WebGL, your video drivers may be too old. To view any of the demos tagged with WebGL, try updating your drivers at NVIDIA, AMD, and Intel. You can still watch screencasts of the WebGL demos or fully experience our other non-WebGL demos without updating. This Mozilla demo gives me "No WebGL context found."

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• Enabling "AllowDualLinkModes" in xorg.conf

  - by Gausie

  I'm using a GeForce GT 620 (which is dual-link compatable) and a DVI-I dual-link splitter to try to have a desktop extended onto two monitors. At the moment when I plug in the monitors, only the monitor on the female VGA marked "1" gets a signal, and the other screen gets nothing and only one screen is detected by nvidia-settings. After reading around, I have realised that my graphics card probably comes with dual-link disabled by default, and I can enable it by adding an "AllowDualLinkModes" option to my xorg.conf. This is the current state of my xorg.conf Section "Device" Identifier "Default Device" Option "NoLogo" "True" EndSection Where do I put the line about AllowDualLinkModes? Do I create a new Section? Have I misunderstood? Cheers Gausie

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• In retrospect, has it been a good idea to use three-valued logic for SQL NULL comparisons?

  - by Heinzi

  In SQL, NULL means "unknown value". Thus, every comparison with NULL yields NULL (unknown) rather than TRUE or FALSE. From a conceptional point of view, this three-valued logic makes sense. From a practical point of view, every learner of SQL has, one time or another, made the classic WHERE myField = NULL mistake or learned the hard way that NOT IN does not do what one would expect when NULL values are present. It is my impression (please correct me if I am wrong) that the cases where this three-valued logic helps (e.g. WHERE myField IS NOT NULL AND myField <> 2 can be shortened to WHERE myField <> 2) are rare and, in those cases, people tend to use the longer version anyway for clarity, just like you would add a comment when using a clever, non-obvious hack. Is there some obvious advantage that I am missing? Or is there a general consensus among the development community that this has been a mistake?

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• Windows 7 doesn't boot after Ubuntu install

  - by Omu

  I had windows 7 installed on my pc, then I installed Ubuntu 10.10/ During the installation process I have chosen to manually set my partitions: I set a 10GB drive for ubuntu root 1GB drive for swap and for boot drive I've chosen the one used by windows 7 Now I can boot ubuntu, I have the windows 7 option in the boot list, but when I choose Windows 7, it shows me a black screen for a second and returns back to boot screen. Boot Info Script 0.55 dated February 15th, 2010 ============================= Boot Info Summary: ============================== = Windows is installed in the MBR of /dev/sda sda1: _________________________________________________________________________ File system: ntfs Boot sector type: Grub 2 Boot sector info: Grub 2 is installed in the boot sector of sda1 and looks at sector 304908237 of the same hard drive for core.img, but core.img can not be found at this location. No errors found in the Boot Parameter Block. Operating System: Windows 7 Boot files/dirs: /bootmgr /Boot/BCD /Windows/System32/winload.exe sda2: _________________________________________________________________________ File system: ntfs Boot sector type: Windows XP Boot sector info: No errors found in the Boot Parameter Block. Operating System: Boot files/dirs: sda3: _________________________________________________________________________ File system: Extended Partition Boot sector type: - Boot sector info: sda5: _________________________________________________________________________ File system: ext4 Boot sector type: - Boot sector info: Operating System: Ubuntu 10.10 Boot files/dirs: /boot/grub/grub.cfg /etc/fstab /boot/grub/core.img sda4: _________________________________________________________________________ File system: swap Boot sector type: - Boot sector info: =========================== Drive/Partition Info: ============================= Drive: sda ___________________ _____________________________________________________ Disk /dev/sda: 160.0 GB, 160041885696 bytes 255 heads, 63 sectors/track, 19457 cylinders, total 312581808 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes Partition Boot Start End Size Id System /dev/sda1 * 63 62,894,474 62,894,412 7 HPFS/NTFS /dev/sda2 62,894,478 291,579,749 228,685,272 7 HPFS/NTFS /dev/sda3 291,579,811 309,157,937 17,578,127 5 Extended /dev/sda5 291,579,813 309,157,937 17,578,125 83 Linux /dev/sda4 309,159,936 312,580,095 3,420,160 82 Linux swap / Solaris blkid -c /dev/null: ____________________________________________________________ Device UUID TYPE LABEL /dev/sda1 1266BB2766BB0A8D ntfs /dev/sda2 BEDBF1147C76F703 ntfs DATA /dev/sda3: PTTYPE="dos" /dev/sda4 dd38226d-c7c9-4ae5-a726-6d18d34a22e4 swap /dev/sda5 e1dafd1c-f855-406b-8f9a-f9d527c70255 ext4 /dev/sda: PTTYPE="dos" ============================ "mount | grep ^/dev output: =========================== Device Mount_Point Type Options /dev/sda5 / ext4 (rw,errors=remount-ro,commit=0) =========================== sda5/boot/grub/grub.cfg: =========================== # # DO NOT EDIT THIS FILE # # It is automatically generated by grub-mkconfig using templates # from /etc/grub.d and settings from /etc/default/grub # ### BEGIN /etc/grub.d/00_header ### if [ -s $prefix/grubenv ]; then set have_grubenv=true load_env fi set default="0" if [ "${prev_saved_entry}" ]; then set saved_entry="${prev_saved_entry}" save_env saved_entry set prev_saved_entry= save_env prev_saved_entry set boot_once=true fi function savedefault { if [ -z "${boot_once}" ]; then saved_entry="${chosen}" save_env saved_entry fi } function recordfail { set recordfail=1 if [ -n "${have_grubenv}" ]; then if [ -z "${boot_once}" ]; then save_env recordfail; fi; fi } function load_video { insmod vbe insmod vga } insmod part_msdos insmod ext2 set root='(hd0,msdos5)' search --no-floppy --fs-uuid --set e1dafd1c-f855-406b-8f9a-f9d527c70255 if loadfont /usr/share/grub/unicode.pf2 ; then set gfxmode=640x480 load_video insmod gfxterm fi terminal_output gfxterm insmod part_msdos insmod ext2 set root='(hd0,msdos5)' search --no-floppy --fs-uuid --set e1dafd1c-f855-406b-8f9a-f9d527c70255 set locale_dir=($root)/boot/grub/locale set lang=en insmod gettext if [ "${recordfail}" = 1 ]; then set timeout=-1 else set timeout=10 fi ### END /etc/grub.d/00_header ### ### BEGIN /etc/grub.d/05_debian_theme ### set menu_color_normal=white/black set menu_color_highlight=black/light-gray ### END /etc/grub.d/05_debian_theme ### ### BEGIN /etc/grub.d/10_linux ### menuentry 'Ubuntu, with Linux 2.6.35-22-generic' --class ubuntu --class gnu-linux --class gnu --class os { recordfail insmod part_msdos insmod ext2 set root='(hd0,msdos5)' search --no-floppy --fs-uuid --set e1dafd1c-f855-406b-8f9a-f9d527c70255 linux /boot/vmlinuz-2.6.35-22-generic root=UUID=e1dafd1c-f855-406b-8f9a-f9d527c70255 ro quiet splash initrd /boot/initrd.img-2.6.35-22-generic } menuentry 'Ubuntu, with Linux 2.6.35-22-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os { recordfail insmod part_msdos insmod ext2 set root='(hd0,msdos5)' search --no-floppy --fs-uuid --set e1dafd1c-f855-406b-8f9a-f9d527c70255 echo 'Loading Linux 2.6.35-22-generic ...' linux /boot/vmlinuz-2.6.35-22-generic root=UUID=e1dafd1c-f855-406b-8f9a-f9d527c70255 ro single echo 'Loading initial ramdisk ...' initrd /boot/initrd.img-2.6.35-22-generic } ### END /etc/grub.d/10_linux ### ### BEGIN /etc/grub.d/20_linux_xen ### ### END /etc/grub.d/20_linux_xen ### ### BEGIN /etc/grub.d/20_memtest86+ ### menuentry "Memory test (memtest86+)" { insmod part_msdos insmod ext2 set root='(hd0,msdos5)' search --no-floppy --fs-uuid --set e1dafd1c-f855-406b-8f9a-f9d527c70255 linux16 /boot/memtest86+.bin } menuentry "Memory test (memtest86+, serial console 115200)" { insmod part_msdos insmod ext2 set root='(hd0,msdos5)' search --no-floppy --fs-uuid --set e1dafd1c-f855-406b-8f9a-f9d527c70255 linux16 /boot/memtest86+.bin console=ttyS0,115200n8 } ### END /etc/grub.d/20_memtest86+ ### ### BEGIN /etc/grub.d/30_os-prober ### menuentry "Windows 7 (loader) (on /dev/sda1)" { insmod part_msdos insmod ntfs set root='(hd0,msdos1)' search --no-floppy --fs-uuid --set 1266bb2766bb0a8d chainloader +1 } ### END /etc/grub.d/30_os-prober ### ### BEGIN /etc/grub.d/40_custom ### # This file provides an easy way to add custom menu entries. Simply type the # menu entries you want to add after this comment. Be careful not to change # the 'exec tail' line above. ### END /etc/grub.d/40_custom ### ### BEGIN /etc/grub.d/41_custom ### if [ -f $prefix/custom.cfg ]; then source $prefix/custom.cfg; fi ### END /etc/grub.d/41_custom ### =============================== sda5/etc/fstab: =============================== # /etc/fstab: static file system information. # # Use 'blkid -o value -s UUID' to print the universally unique identifier # for a device; this may be used with UUID= as a more robust way to name # devices that works even if disks are added and removed. See fstab(5). # # proc /proc proc nodev,noexec,nosuid 0 0 /dev/sda5 / ext4 errors=remount-ro 0 1 # swap was on /dev/sda4 during installation UUID=dd38226d-c7c9-4ae5-a726-6d18d34a22e4 none swap sw 0 0 =================== sda5: Location of files loaded by Grub: =================== 156.1GB: boot/grub/core.img 156.3GB: boot/grub/grub.cfg 149.9GB: boot/initrd.img-2.6.35-22-generic 156.3GB: boot/vmlinuz-2.6.35-22-generic 149.9GB: initrd.img 156.3GB: vmlinuz

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• Undocumented Gmail Search Operator Ferrets Out Large Email Attachments

  - by Jason Fitzpatrick

  If you’re looking for a way to quickly find large email attachments in your Gmail account, this undocumented search operator makes it simple to zero in on the hulking attachments hiding out in your inbox. To use the search operator simply plug in “size:” and some value to narrow your search to only emails that size or larger. In the screenshot above we searched for “size:20000000″ to search for files roughly 20MB or larger (if you want to be extremely precise, a true 20MB search would be “size:20971520″). If you’re looking to clean up your Gmail account this is a nearly zero-effort way to find the biggest space hogs–in our case, we found an email packed with massive PDF files from a 5 year old project that we were more than happy to purge. Finding Large Attachments in Google Mail/Gmail [via gHacks] 6 Ways Windows 8 Is More Secure Than Windows 7 HTG Explains: Why It’s Good That Your Computer’s RAM Is Full 10 Awesome Improvements For Desktop Users in Windows 8

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• Why I can't install new fonts in LibreOffice?

  - by uzumaki

  I have installed a lot of fonts before, but this time things are really different. I have downloaded some True Type Font (ttf) fonts. Then paste them in the directory usr/share/fonts after that I've restarted LibreOffice writer but don't find them in the font list. No better result with PC rebooting. Then again paste them in the directory usr/share/fonts/truetype and again restarted LibreOffice writer, but still they aren't on the font list. I've tried in another way. Opened the fonts with font viewer and click on the "install" but the result is same. No improvement at all. Latest I've just found that those specific fonts are installed on my system, they present on gedit font list,but not in the LibreOffice font list. So, may be the problem is with LibreOffice. Very surprising and irritating issue indeed.

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• Using TPL and PLINQ to raise performance of feed aggregator

  - by DigiMortal

  In this posting I will show you how to use Task Parallel Library (TPL) and PLINQ features to boost performance of simple RSS-feed aggregator. I will use here only very basic .NET classes that almost every developer starts from when learning parallel programming. Of course, we will also measure how every optimization affects performance of feed aggregator. Feed aggregator Our feed aggregator works as follows: Load list of blogs Download RSS-feed Parse feed XML Add new posts to database Our feed aggregator is run by task scheduler after every 15 minutes by example. We will start our journey with serial implementation of feed aggregator. Second step is to use task parallelism and parallelize feeds downloading and parsing. And our last step is to use data parallelism to parallelize database operations. We will use Stopwatch class to measure how much time it takes for aggregator to download and insert all posts from all registered blogs. After every run we empty posts table in database. Serial aggregation Before doing parallel stuff let’s take a look at serial implementation of feed aggregator. All tasks happen one after other. internal class FeedClient {     private readonly INewsService _newsService;     private const int FeedItemContentMaxLength = 255;       public FeedClient()     {          ObjectFactory.Initialize(container =>          {              container.PullConfigurationFromAppConfig = true;          });           _newsService = ObjectFactory.GetInstance<INewsService>();     }       public void Execute()     {         var blogs = _newsService.ListPublishedBlogs();           for (var index = 0; index <blogs.Count; index++)         {              ImportFeed(blogs[index]);         }     }       private void ImportFeed(BlogDto blog)     {         if(blog == null)             return;         if (string.IsNullOrEmpty(blog.RssUrl))             return;           var uri = new Uri(blog.RssUrl);         SyndicationContentFormat feedFormat;           feedFormat = SyndicationDiscoveryUtility.SyndicationContentFormatGet(uri);           if (feedFormat == SyndicationContentFormat.Rss)             ImportRssFeed(blog);         if (feedFormat == SyndicationContentFormat.Atom)             ImportAtomFeed(blog);                 }       private void ImportRssFeed(BlogDto blog)     {         var uri = new Uri(blog.RssUrl);         var feed = RssFeed.Create(uri);           foreach (var item in feed.Channel.Items)         {             SaveRssFeedItem(item, blog.Id, blog.CreatedById);         }     }       private void ImportAtomFeed(BlogDto blog)     {         var uri = new Uri(blog.RssUrl);         var feed = AtomFeed.Create(uri);           foreach (var item in feed.Entries)         {             SaveAtomFeedEntry(item, blog.Id, blog.CreatedById);         }     } } Serial implementation of feed aggregator downloads and inserts all posts with 25.46 seconds. Task parallelism Task parallelism means that separate tasks are run in parallel. You can find out more about task parallelism from MSDN page Task Parallelism (Task Parallel Library) and Wikipedia page Task parallelism. Although finding parts of code that can run safely in parallel without synchronization issues is not easy task we are lucky this time. Feeds import and parsing is perfect candidate for parallel tasks. We can safely parallelize feeds import because importing tasks doesn’t share any resources and therefore they don’t also need any synchronization. After getting the list of blogs we iterate through the collection and start new TPL task for each blog feed aggregation. internal class FeedClient {     private readonly INewsService _newsService;     private const int FeedItemContentMaxLength = 255;       public FeedClient()     {          ObjectFactory.Initialize(container =>          {              container.PullConfigurationFromAppConfig = true;          });           _newsService = ObjectFactory.GetInstance<INewsService>();     }       public void Execute()     {         var blogs = _newsService.ListPublishedBlogs();                var tasks = new Task[blogs.Count];           for (var index = 0; index <blogs.Count; index++)         {             tasks[index] = new Task(ImportFeed, blogs[index]);             tasks[index].Start();         }           Task.WaitAll(tasks);     }       private void ImportFeed(object blogObject)     {         if(blogObject == null)             return;         var blog = (BlogDto)blogObject;         if (string.IsNullOrEmpty(blog.RssUrl))             return;           var uri = new Uri(blog.RssUrl);         SyndicationContentFormat feedFormat;           feedFormat = SyndicationDiscoveryUtility.SyndicationContentFormatGet(uri);           if (feedFormat == SyndicationContentFormat.Rss)             ImportRssFeed(blog);         if (feedFormat == SyndicationContentFormat.Atom)             ImportAtomFeed(blog);                }       private void ImportRssFeed(BlogDto blog)     {          var uri = new Uri(blog.RssUrl);          var feed = RssFeed.Create(uri);           foreach (var item in feed.Channel.Items)          {              SaveRssFeedItem(item, blog.Id, blog.CreatedById);          }     }     private void ImportAtomFeed(BlogDto blog)     {         var uri = new Uri(blog.RssUrl);         var feed = AtomFeed.Create(uri);           foreach (var item in feed.Entries)         {             SaveAtomFeedEntry(item, blog.Id, blog.CreatedById);         }     } } You should notice first signs of the power of TPL. We made only minor changes to our code to parallelize blog feeds aggregating. On my machine this modification gives some performance boost – time is now 17.57 seconds. Data parallelism There is one more way how to parallelize activities. Previous section introduced task or operation based parallelism, this section introduces data based parallelism. By MSDN page Data Parallelism (Task Parallel Library) data parallelism refers to scenario in which the same operation is performed concurrently on elements in a source collection or array. In our code we have independent collections we can process in parallel – imported feed entries. As checking for feed entry existence and inserting it if it is missing from database doesn’t affect other entries the imported feed entries collection is ideal candidate for parallelization. internal class FeedClient {     private readonly INewsService _newsService;     private const int FeedItemContentMaxLength = 255;       public FeedClient()     {          ObjectFactory.Initialize(container =>          {              container.PullConfigurationFromAppConfig = true;          });           _newsService = ObjectFactory.GetInstance<INewsService>();     }       public void Execute()     {         var blogs = _newsService.ListPublishedBlogs();                var tasks = new Task[blogs.Count];           for (var index = 0; index <blogs.Count; index++)         {             tasks[index] = new Task(ImportFeed, blogs[index]);             tasks[index].Start();         }           Task.WaitAll(tasks);     }       private void ImportFeed(object blogObject)     {         if(blogObject == null)             return;         var blog = (BlogDto)blogObject;         if (string.IsNullOrEmpty(blog.RssUrl))             return;           var uri = new Uri(blog.RssUrl);         SyndicationContentFormat feedFormat;           feedFormat = SyndicationDiscoveryUtility.SyndicationContentFormatGet(uri);           if (feedFormat == SyndicationContentFormat.Rss)             ImportRssFeed(blog);         if (feedFormat == SyndicationContentFormat.Atom)             ImportAtomFeed(blog);                }       private void ImportRssFeed(BlogDto blog)     {         var uri = new Uri(blog.RssUrl);         var feed = RssFeed.Create(uri);           feed.Channel.Items.AsParallel().ForAll(a =>         {             SaveRssFeedItem(a, blog.Id, blog.CreatedById);         });      }        private void ImportAtomFeed(BlogDto blog)      {         var uri = new Uri(blog.RssUrl);         var feed = AtomFeed.Create(uri);           feed.Entries.AsParallel().ForAll(a =>         {              SaveAtomFeedEntry(a, blog.Id, blog.CreatedById);         });      } } We did small change again and as the result we parallelized checking and saving of feed items. This change was data centric as we applied same operation to all elements in collection. On my machine I got better performance again. Time is now 11.22 seconds. Results Let’s visualize our measurement results (numbers are given in seconds). As we can see then with task parallelism feed aggregation takes about 25% less time than in original case. When adding data parallelism to task parallelism our aggregation takes about 2.3 times less time than in original case. More about TPL and PLINQ Adding parallelism to your application can be very challenging task. You have to carefully find out parts of your code where you can safely go to parallel processing and even then you have to measure the effects of parallel processing to find out if parallel code performs better. If you are not careful then troubles you will face later are worse than ones you have seen before (imagine error that occurs by average only once per 10000 code runs). Parallel programming is something that is hard to ignore. Effective programs are able to use multiple cores of processors. Using TPL you can also set degree of parallelism so your application doesn’t use all computing cores and leaves one or more of them free for host system and other processes. And there are many more things in TPL that make it easier for you to start and go on with parallel programming. In next major version all .NET languages will have built-in support for parallel programming. There will be also new language constructs that support parallel programming. Currently you can download Visual Studio Async to get some idea about what is coming. Conclusion Parallel programming is very challenging but good tools offered by Visual Studio and .NET Framework make it way easier for us. In this posting we started with feed aggregator that imports feed items on serial mode. With two steps we parallelized feed importing and entries inserting gaining 2.3 times raise in performance. Although this number is specific to my test environment it shows clearly that parallel programming may raise the performance of your application significantly.

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• Why aren't we all doing model driven development yet ?

  - by KeesDijk

  I am a true believer in Model Driven Development, I think it has the possibility to increase productivity, quality and predictability. When looking at MetaEdit the results are amazing. Mendix in the Netherlands is growing very very fast and has great results. I also know there are a lot of problems versioning of generators, templates and framework projects that just aren't right for model driven development (not enough repetition) higher risks (when the first project fails, you have less results than you would have with more traditional development) etc But still these problems seem solvable and the benefits should outweigh the effort needed. Question: What do you see as the biggest problems that make you not even consider model driven development ? I want to use these answers not just for my own understanding but also as a possible source for a series of internal articles I plan to write.

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• Striving to be boring - or at least have boring systems

  - by merrillaldrich

  A developer I work with, whom I respect a great deal, reminded me of this truism today. I'm not sure who came up with the original, but they deserve credit wherever they are: “A good system administrator is a bored system administrator.” As a DBA, this really rings true for me. Being a DBA should not be a thrilling job. Within reason, there should not be myriad surprises, nor a roller coaster ride, wondering what will break each day. There should not be numerous 2 AM calls or frantic fixes. If there...(read more)

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