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  • Does anyone really understand how HFSC scheduling in Linux/BSD works?

    - by Mecki
    I read the original SIGCOMM '97 PostScript paper about HFSC, it is very technically, but I understand the basic concept. Instead of giving a linear service curve (as with pretty much every other scheduling algorithm), you can specify a convex or concave service curve and thus it is possible to decouple bandwidth and delay. However, even though this paper mentions to kind of scheduling algorithms being used (real-time and link-share), it always only mentions ONE curve per scheduling class (the decoupling is done by specifying this curve, only one curve is needed for that). Now HFSC has been implemented for BSD (OpenBSD, FreeBSD, etc.) using the ALTQ scheduling framework and it has been implemented Linux using the TC scheduling framework (part of iproute2). Both implementations added two additional service curves, that were NOT in the original paper! A real-time service curve and an upper-limit service curve. Again, please note that the original paper mentions two scheduling algorithms (real-time and link-share), but in that paper both work with one single service curve. There never have been two independent service curves for either one as you currently find in BSD and Linux. Even worse, some version of ALTQ seems to add an additional queue priority to HSFC (there is no such thing as priority in the original paper either). I found several BSD HowTo's mentioning this priority setting (even though the man page of the latest ALTQ release knows no such parameter for HSFC, so officially it does not even exist). This all makes the HFSC scheduling even more complex than the algorithm described in the original paper and there are tons of tutorials on the Internet that often contradict each other, one claiming the opposite of the other one. This is probably the main reason why nobody really seems to understand how HFSC scheduling really works. Before I can ask my questions, we need a sample setup of some kind. I'll use a very simple one as seen in the image below: Here are some questions I cannot answer because the tutorials contradict each other: What for do I need a real-time curve at all? Assuming A1, A2, B1, B2 are all 128 kbit/s link-share (no real-time curve for either one), then each of those will get 128 kbit/s if the root has 512 kbit/s to distribute (and A and B are both 256 kbit/s of course), right? Why would I additionally give A1 and B1 a real-time curve with 128 kbit/s? What would this be good for? To give those two a higher priority? According to original paper I can give them a higher priority by using a curve, that's what HFSC is all about after all. By giving both classes a curve of [256kbit/s 20ms 128kbit/s] both have twice the priority than A2 and B2 automatically (still only getting 128 kbit/s on average) Does the real-time bandwidth count towards the link-share bandwidth? E.g. if A1 and B1 both only have 64kbit/s real-time and 64kbit/s link-share bandwidth, does that mean once they are served 64kbit/s via real-time, their link-share requirement is satisfied as well (they might get excess bandwidth, but lets ignore that for a second) or does that mean they get another 64 kbit/s via link-share? So does each class has a bandwidth "requirement" of real-time plus link-share? Or does a class only have a higher requirement than the real-time curve if the link-share curve is higher than the real-time curve (current link-share requirement equals specified link-share requirement minus real-time bandwidth already provided to this class)? Is upper limit curve applied to real-time as well, only to link-share, or maybe to both? Some tutorials say one way, some say the other way. Some even claim upper-limit is the maximum for real-time bandwidth + link-share bandwidth? What is the truth? Assuming A2 and B2 are both 128 kbit/s, does it make any difference if A1 and B1 are 128 kbit/s link-share only, or 64 kbit/s real-time and 128 kbit/s link-share, and if so, what difference? If I use the seperate real-time curve to increase priorities of classes, why would I need "curves" at all? Why is not real-time a flat value and link-share also a flat value? Why are both curves? The need for curves is clear in the original paper, because there is only one attribute of that kind per class. But now, having three attributes (real-time, link-share, and upper-limit) what for do I still need curves on each one? Why would I want the curves shape (not average bandwidth, but their slopes) to be different for real-time and link-share traffic? According to the little documentation available, real-time curve values are totally ignored for inner classes (class A and B), they are only applied to leaf classes (A1, A2, B1, B2). If that is true, why does the ALTQ HFSC sample configuration (search for 3.3 Sample configuration) set real-time curves on inner classes and claims that those set the guaranteed rate of those inner classes? Isn't that completely pointless? (note: pshare sets the link-share curve in ALTQ and grate the real-time curve; you can see this in the paragraph above the sample configuration). Some tutorials say the sum of all real-time curves may not be higher than 80% of the line speed, others say it must not be higher than 70% of the line speed. Which one is right or are they maybe both wrong? One tutorial said you shall forget all the theory. No matter how things really work (schedulers and bandwidth distribution), imagine the three curves according to the following "simplified mind model": real-time is the guaranteed bandwidth that this class will always get. link-share is the bandwidth that this class wants to become fully satisfied, but satisfaction cannot be guaranteed. In case there is excess bandwidth, the class might even get offered more bandwidth than necessary to become satisfied, but it may never use more than upper-limit says. For all this to work, the sum of all real-time bandwidths may not be above xx% of the line speed (see question above, the percentage varies). Question: Is this more or less accurate or a total misunderstanding of HSFC? And if assumption above is really accurate, where is prioritization in that model? E.g. every class might have a real-time bandwidth (guaranteed), a link-share bandwidth (not guaranteed) and an maybe an upper-limit, but still some classes have higher priority needs than other classes. In that case I must still prioritize somehow, even among real-time traffic of those classes. Would I prioritize by the slope of the curves? And if so, which curve? The real-time curve? The link-share curve? The upper-limit curve? All of them? Would I give all of them the same slope or each a different one and how to find out the right slope? I still haven't lost hope that there exists at least a hand full of people in this world that really understood HFSC and are able to answer all these questions accurately. And doing so without contradicting each other in the answers would be really nice ;-)

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  • Asp.Net 3.5 Routing to Webservice?

    - by Maushu
    I was looking for a way to route http://www.example.com/WebService.asmx to http://www.example.com/service/ using only the ASP.NET 3.5 Routing framework without needing to configure the IIS server. Until now I have done what most tutorials told me, added a reference to the routing assembly, configured stuff in the web.config, added this to the Global.asax: protected void Application_Start(object sender, EventArgs e) { RouteCollection routes = RouteTable.Routes; routes.Add( "WebService", new Route("service/{*Action}", new WebServiceRouteHandler()) ); } ...created this class: public class WebServiceRouteHandler : IRouteHandler { public IHttpHandler GetHttpHandler(RequestContext requestContext) { // What now? } } ...and the problem is right there, I don't know what to do. The tutorials and guides I've read use routing for pages, not webservices. Is this even possible? Ps: The route handler is working, I can visit /service/ and it throws the NotImplementedException I left in the GetHttpHandler method.

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  • communicating swf files.

    - by Addis Abebayehu
    I have two swf files I would like communicate. I have a videoplaylist.swf and a player.swf. I would like to select a video from videoplaylist.swf and have it played in the player.swf. How do I do that? How am I going to dispatch the click event with the video url to the player.swf? from the videoplaylist.swf. Please help.

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  • Getting keyboard size from user info in Swift

    - by user3746428
    I have been trying to add some code to move my view up when the keyboard appears, however I am having issues trying to translate the Objective C examples into Swift. I have made some progress but I am stuck on one particular line. These are the two tutorials/questions I have been following: How to move content of UIViewController upwards as Keypad appears using Swift http://www.ioscreator.com/tutorials/move-view-when-keyboard-appears Here is the code I currently have: override func viewWillAppear(animated: Bool) { NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillShow:", name: UIKeyboardWillShowNotification, object: nil) NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillHide:", name: UIKeyboardWillHideNotification, object: nil) } override func viewWillDisappear(animated: Bool) { NSNotificationCenter.defaultCenter().removeObserver(self) } func keyboardWillShow(notification: NSNotification) { var keyboardSize = notification.userInfo(valueForKey(UIKeyboardFrameBeginUserInfoKey)) UIEdgeInsets(top: 0, left: 0, bottom: keyboardSize.height, right: 0) let frame = self.budgetEntryView.frame frame.origin.y = frame.origin.y - keyboardSize self.budgetEntryView.frame = frame } func keyboardWillHide(notification: NSNotification) { // } At the moment I am getting an error on this line: var keyboardSize = notification.userInfo(valueForKey(UIKeyboardFrameBeginUserInfoKey)) If someone could let me know what this line of code should be, I should manage to figure out the rest myself.

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  • Web Standards alternatives to Flex/Silverlight (I mean serious alternatives, not just JS framewoks)

    - by user252160
    Is there a set of open standards technologies that I can use to achieve the same way of development as in Flex and Sivlerlight? I am talking about componentization, separation of concerns, rich graphics, states and effects . Please point out some tutorials and other resources if possible. P.S. I KNOW that this is technically possible, so please do not respond by sending google search results or general JQuery tutorials. I've seen those already. I need to know how a Flex / Silverlight developer could design and implement an application in roughly the same way (imagine a rich HTML tag set, much like XAML/MXML, behind which stands JavaScript responsible for handling events and business logic. Think also about binding)

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  • Java Swing: how to add an image to a JPanel ?

    - by Leonel
    I have a JPanel to which I'd like to add JPEG and PNG images that I generate on the fly. All the examples I've seen so far in the Swing Tutorials, specially in the Swing examples use ImageIcons. I'm generating these images as byte arrays, and they are usually larger than the common icon they use in the examples, at 640x480. Is there any (performance or other) problem in using the ImageIcon class to display an image that size in a JPanel ? What's the usual way of doing it ? How to add an image to a JPanel without using the ImageIcon class ? Edit: A more careful examination of the tutorials and the API shows that you cannot add an ImageIcon directly to a JPanel. Instead, they achieve the same effect by setting the image as an icon of a JLabel. This just doesn't fill right...

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  • Easiest Way to Parse data from twitter with Coccoa

    - by happyCoding25
    Hello, Im followed the tutorial from here: Twitter Client Tutorial to make a little twitter app. Now I need to find out how to parse the XML twitter gives you when you make a request. I've looked at tons of tutorials on phrasing xml on the iPhone but none have made much sense because Im still new to cocoa. Twitter stores the text of the tweet in something like this <text> Some tweet here </text>. From reading the tutorials I think this would involve nsxmlparser but I'm not sure. If anyone could share some code that could parse the <text> Some tweet here </text> things into an array that would be really great. Thanks in advance

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  • How to acquire still webcam image

    - by Silv3rSurf
    I need some help deciding what to use to acquire an image from a webcam. I want to acquire a single image. I know you can typically acquire a still image at a higher resolution than a single video frame. Currently, I am using MATLAB's image acquisition toolbox.. which apparently only supports obtaining frames in video mode(so lower resolution). Which other libraries do you recommend? Has anyone else encountered this problem?

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  • Getting problem in Java OpenCV code.

    - by Chetan
    I had successfully compile my java code in Eclipse with name FaceDetection.java... I am getting an Exception in thread "main" java.lang.NoSuchMethodError: main.... Please help me to remove this Exception.. Here is the code import java.awt.; import java.awt.event.; import java.awt.image.MemoryImageSource; import hypermedia.video.OpenCV; @SuppressWarnings("serial") public class FaceDetection extends Frame implements Runnable { /** * Main method. * @param String[] a list of user's arguments passed from the console to this program */ public static void main( String[] args ) { System.out.println( "\nOpenCV face detection sample\n" ); new FaceDetection(); } // program execution frame rate (millisecond) final int FRAME_RATE = 1000/30; OpenCV cv = null; // OpenCV Object Thread t = null; // the sample thread // the input video stream image Image frame = null; // list of all face detected area Rectangle[] squares = new Rectangle[0]; /** * Setup Frame and Object(s). */ FaceDetection() { super( "Face Detection Sample" ); // OpenCV setup cv = new OpenCV(); cv.capture( 320, 240 ); cv.cascade( OpenCV.CASCADE_FRONTALFACE_ALT ); // frame setup this.setBounds( 100, 100, cv.width, cv.height ); this.setBackground( Color.BLACK ); this.setVisible( true ); this.addKeyListener( new KeyAdapter() { public void keyReleased( KeyEvent e ) { if ( e.getKeyCode()==KeyEvent.VK_ESCAPE ) { // ESC : release OpenCV resources cv.dispose(); System.exit(0); } } } ); // start running program t = new Thread( this ); t.start(); } /** * Draw video frame and each detected faces area. */ public void paint( Graphics g ) { // draw image g.drawImage( frame, 0, 0, null ); // draw squares g.setColor( Color.RED ); for( Rectangle rect : squares ) g.drawRect( rect.x, rect.y, rect.width, rect.height ); } /** * Execute this sample. */ @SuppressWarnings("static-access") public void run() { while( t!=null && cv!=null ) { try { t.sleep( FRAME_RATE ); // grab image from video stream cv.read(); // create a new image from cv pixels data MemoryImageSource mis = new MemoryImageSource( cv.width, cv.height, cv.pixels(), 0, cv.width ); frame = createImage( mis ); // detect faces squares = cv.detect( 1.2f, 2, OpenCV.HAAR_DO_CANNY_PRUNING, 20, 20 ); // of course, repaint repaint(); } catch( InterruptedException e ) {;} } } }

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  • Creating xaml 'template' for multiple pages

    - by superexsl
    Hey, I'm developing a Silverlight application for the first time. I've gone through some tutorials, but I can't seem to find anything that helps me with this particular problem. I would like a set of buttons to be present on all of my pages (like a template). When a button is pressed, I would like the ContentGrid to slide out and a new ContentGrid slide in (with the relevant .xaml file being loaded). Are there any tutorials showing the best way to do this? From samples I've seen, they only seem to transition between two pages, so copy-pasting the group of buttons on each xaml page isn't too much of a problem. However, with more pages, it would be inefficient to copy-paste the base layout each time. Thanks for any suggestions

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  • VisualAssert Testing in C++, Loading a test fixture.

    - by C_Bevan
    Good day, I am learning Testing in Visual Studio C++ and I have several tutorials which I have followed. I am trying to load a test fixture. I have tried to put the test .cpp file in many different places but it will still not pick up on it when I click on "Run Tests" or "Run Tests without debugging" In the tutorials I found, they seemed to load into the Test Explorer automatically, but in mine is an icon with a X + (PROJECTNAME).EXE and when I hoover over it I get the process exited without registering with the agent... this is due to the model not containing any test fixtures... How can I load my tests into the Test Explorer...or register them with my project... I've tried right click and "Add Fixture...".... but that just starts a new test file and I have the same problem. Anybody know how I solve this issue?

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  • Using Qtcreator (with Qwt), really basic stuff

    - by Dago
    I'm trying to make a Qt program using Qtcreator and Qwt for plotting. I've never used Qtcreator before. I've created a mainwindow and added a Qwtplot widget there (object name: qwtPlot). The widget shows up in the program when I compile and run it. But theres no mention of the qwtPlot object anywhere in the (autogenerated) code so I assume it is being added at compile time from the .ui xml file (or something). My question is that... how do I modify/change the qwtPlot object? Or where should I place the code. I'm having a hard time articulating my question but the question basically is "How do I do anything with the qwtPlot widget which is created (graphically) with Qtcreator?". I've checked some tutorials but in the tutorials they add the widgets manually in the code, but I'd like to use Qtcreator (because my UI will be fairly complicated). This whole Qtcreator is pretty confusing...

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  • ASP.NET MVC reminds me of old Classic ASP spaghetti code...

    - by EdenMachine
    I just went through some MVC tutorials after checking this site out for a while. Is it just me, or does MVC View pages brinig back HORRIBLE flashbacks of Classic ASP spaghetti code with all the jumping in and out of HTML and ASP.NET with yellow delimiters everywhere making it impossible to read? What ever happened to the importance of code/design separation?? I was really sold on the new technology until the tutorials hit the View page development section. Or am I missing something? (And don't say you can use the template to help because it's jsut moving the spaghetti to another location - sweeps it under the rug - it doesn't fix the problem)

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  • What is the best way to get my avi files into flv format?

    - by Andrew G. Johnson
    I need to embed videos on a client's website and they have given the following guidelines: must be viewable as flash (FLV format) if hosted by outside company (e.g. Youtube) the video can not link back to the outside company's website if hosted by outside company (e.g. Youtube) the video can not have any advertisements of the outside company I guess what I'm looking for is an AVI-to-FLV converter?

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  • postmessage for directinput

    - by kevin
    can someone PLEASE point me in the right direction all i want to do is simulate a mouse click in a video game that is minimized the video game i am doing this for allows macroing like this, so its all good however, the game uses directinput so using postmessage and sendmessage is not working

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  • PCAP Web Service Usage Logging for Dummies

    - by nick
    I've been assigned the task (for work) of working with PCAP for the first time in my life. I've read through the tutorials and have hacked together a real simple capture program which, it turns out, isn't that hard. However, making use of the data is more difficult. My goal is to log incomming and outgoing web service requests. Are there libraries (C or C++) that stitch together the packets from PCAP that would make reporting on this simple? Baring that is there something short of reading all of the RFC's from soup to nuts that will allow me to have an "ah-ha!" moment (all of the tutorials seem to stop at the raw packet level which isn't useful for me)? It looks like PERL has a library that may do this and I may eventually attempt a reverse engineer from PERL. NOTE BENE: Web Server logs aren't acceptable here as I will be intercepting on a routing device. If I had access to those I'd be done and happy...I don't.

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  • newb to assembly programming

    - by ida
    i am on a mac (10.6.3) with snow leopard. i hear that the assembly language i work with has to be valid with the chipset that you use. i am completly new to this i have a basic background in C and Objective-C programming and an almost strong background in php. Ive always wanted to see what assembly is all about. the tutorial ill be looking at is by VTC via (http://www.vtc.com/products/Assembly-Language-Programming-Tutorials.htm). what i want to know is are the tutorials that im about to do compatible with the version of mac that i have? sorry i am completly new to this language although i do recall studying some of it way way back in the day. i do have xcode and what i'm wondering is what kind of document would i open in xcode to work with assembly and does the mac have a built in hex editor (when it comes time to needing it)? thanks

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  • Entity Framework Polymorphism

    - by Chubbs
    Hey guys, I wanted some help with trying to implement a simple polymorphic relationship using Entity Framework. An example of a relationship I would like to implement: Comment table ItemType ('Video', 'User') ItemID Body Video has many Comments User has many Comments No idea the best way to do this, I come from a Ruby on Rails way of thinking.

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  • How to still webcam image

    - by Silv3rSurf
    I need some help deciding what to use to acquire an image from a webcam. I want to acquire a single image. I know you can typically acquire a still image at a higher resolution than a single video frame. Currently, I am using MATLAB's image acquisition toolbox.. which apparently only supports obtaining frames in video mode(so lower resolution). Which other libraries do you recommend? Has anyone else encountered this problem?

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  • For what to use VI?

    - by Zikko
    I recently started picking up VI, going through some tutorials and trying to get used to it. But I still have some questions about it. It seems to be nice for small one file changes, but as soon as I start to try doing bigger things it seems to be lacking. For example I'm used to have code formatting, import organizing, simple overview over all packages and other things that an IDE gives me. I saw some tutorials on how to use VI as an IDE, but it felt awkward at best. Now I'm just wondering, what are the typical use cases for VI? Is it typically used to edit small files, or can it be used for larger projects? And if you use it in larger projects, how do you make it work? Or would it be a lot easier to use an IDE with VI keybindings?

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  • Code hot swapping in Erlang

    - by Roger Alsing
    I recently saw a video about Erlang on InfoQ, In that video one of the creators presented how to replace the behavior of a message loop. He was simply sending a message containing a lambda of the new version of the message loop code, which then was invoked instead of calling the old loop again. Is that code hot swapping in Erlang reffers to? Or is that some other more native feature?

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