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  • Is the "message" of an exception culturally independent?

    - by Ray Hayes
    In an application I'm developing, I have the need to handle a socket-timeout differently from a general socket exception. The problem is that many different issues result in a SocketException and I need to know what the cause was. There is no inner exception reported, so the only information I have to work with is the message: "A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond" This question has a general and specific part: is it acceptable to write conditional logic based upon the textual representation of an exception? Is there a way to avoid needing exception handling? Example code below... try { IPEndPoint endPoint = null; client.Client.ReceiveTimeout = 1000; bytes = client.Receive(ref endPoint); } catch( SocketException se ) { if ( se.Message.Contains("did not properly respond after a period of time") ) { // Handle timeout differently.. } }

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  • How to check the system is Windows 7 or Windows Server 2008 RC in Wix Installer?

    - by Ray
    Hi there, I am working on a windows installer project. And now I only want the software only can be installed on Windows 7 or Windows Server 2008 RC system, I tried to use this: <Condition Message='Windows Server 2008 R2 or Windows 7 is required'>(VersionNT = 600 AND ServicePackLevel = 1) OR VersionNT = 601 </Condition> but it can still be installed on Windows Vista. Please help! Thank you!

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  • Can't add or remove object from NSMutableSet

    - by Dan Ray
    Check it: - (IBAction)toggleFavorite { DataManager *data = [DataManager sharedDataManager]; NSMutableSet *favorites = data.favorites; if (thisEvent.isFavorite == YES) { NSLog(@"Toggling off"); thisEvent.isFavorite = NO; [favorites removeObject:thisEvent.guid]; [favoriteIcon setImage:[UIImage imageNamed:@"notFavorite.png"] forState:UIControlStateNormal]; } else { NSLog(@"Toggling on, adding %@", thisEvent.guid); thisEvent.isFavorite = YES; [favorites addObject:thisEvent.guid]; [favoriteIcon setImage:[UIImage imageNamed:@"isFavorite.png"] forState:UIControlStateNormal]; } NSLog(@"favorites array now contains %d members", [favorites count]); } This is fired from a custom UIButton. The UI part works great--toggles the image used for the button, and I can see from other stuff that the thisEvent.isFavorite BOOL is toggling happily. I can also see in the debugger that I'm getting my DataManager singleton. But here's my NSLog: 2010-05-13 08:24:32.946 MyApp[924:207] Toggling on, adding 05db685f65e2 2010-05-13 08:24:32.947 MyApp[924:207] favorites array now contains 0 members 2010-05-13 08:24:33.666 MyApp[924:207] Toggling off 2010-05-13 08:24:33.666 MyApp[924:207] favorites array now contains 0 members 2010-05-13 08:24:34.060 MyApp[924:207] Toggling on, adding 05db685f65e2 2010-05-13 08:24:34.061 MyApp[924:207] favorites array now contains 0 members 2010-05-13 08:24:34.296 MyApp[924:207] Toggling off 2010-05-13 08:24:34.297 MyApp[924:207] favorites array now contains 0 members Worst part is, this USED to work, and I don't know what I did to break it.

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  • Chaining Many-To-Many Dimensional Relationships in SSAS

    - by Ray Saltrelli
    I'm developing a cube in SSAS and attempting to model the following relationships: Many Facts to 1 Customer Many Customers to Many Sales Reps Many Sales Reps (Subordinates) to Sales Reps (Managers) Each M2M relationship is facilitated by a bridge table which also acts as a fact table in the cube I have most of this working. I can slice Facts by Customer and by Sales Rep (Subordinate), but when I add Sales Rep (Manager) to the query it appears to return every subordinate/manager combination regardless of whether or not that relationship exists in the bridge table. Any ideas as to what I might be doing wrong?

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  • How to do orientation rotation like built-in Calc app?

    - by Ray Wenderlich
    I'm trying to make an app that handles orientation/rotation similarly to the way the built-in Calc app does. If you check out that app, in portrait mode there's a normal calculator, and if you rotate to landscape mode there are additional buttons that appear to the left. I can't figure out how to do this by setting the autosize masks. The problem is the "normal" calculator view is 320px wide in portrait mode, but actually shrinks to around 240px in landscape mode to fit the additional controls. I've seen examples like the AlternateViews sample app that have two different view controllers (one for portrait and one for landscape), but they don't seem to animate the transitions between the views nicely like the Calc app does. I've also tried setting the frames for the views manually in willAnimateSecondHalfOfRotationFromInterfaceOrientation, but it doesn't seem to look "quite right" and also I'm not certain how that works with the autoresize mask. Any ideas how this is done? Thanks!

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  • Using a Data Management Singleton

    - by Dan Ray
    Here's my singleton code (pretty much boilerplate): @interface DataManager : NSObject { NSMutableArray *eventList; } @property (nonatomic, retain) NSMutableArray *eventList; +(DataManager*)sharedDataManager; @end And then the .m: #import "DataManager.h" static DataManager *singletonDataManager = nil; @implementation DataManager @synthesize eventList; +(DataManager*)sharedDataManager { @synchronized(self) { if (!singletonDataManager) { singletonDataManager = [[DataManager alloc] init]; } } NSLog(@"Pulling a copy of shared manager."); return singletonDataManager; } So then in my AppDelegate, I load some stuff before launching my first view: NSMutableArray *eventList = [DataManager sharedDataManager].eventList; .... NSLog(@"Adding event %@ to eventList", event.title); [eventList addObject:event]; NSLog(@"eventList now has %d members", [eventList count]); [event release]; As you can see, I've peppered the code with NSLog love notes to myself. The output to the Log reads like: 2010-05-10 09:08:53.355 MyApp[2037:207] Adding event Woofstock Music Festival to eventList 2010-05-10 09:08:53.355 MyApp[2037:207] eventList now has 0 members 2010-05-10 09:08:53.411 MyApp[2037:207] Adding event Test Event for Staging to eventList 2010-05-10 09:08:53.411 MyApp[2037:207] eventList now has 0 members 2010-05-10 09:08:53.467 MyApp[2037:207] Adding event Montgomery Event to eventList 2010-05-10 09:08:53.467 MyApp[2037:207] eventList now has 0 members 2010-05-10 09:08:53.524 MyApp[2037:207] Adding event Alamance County Event For June to eventList 2010-05-10 09:08:53.524 MyApp[2037:207] eventList now has 0 members ... What gives? I have no errors getting to my eventList NSMutableArray. But I addObject: fails silently?

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  • How to check the system is Windows 7 or Windows Server 2008 R2 in Wix Installer?

    - by Ray
    Hi there, I am working on a windows installer project. And now I only want the software only can be installed on Windows 7 or Windows Server 2008 R2 system, I tried to use this: <Condition Message='Windows Server 2008 R2 or Windows 7 is required'>(VersionNT = 600 AND ServicePackLevel = 1) OR VersionNT = 601 </Condition> but it can still be installed on Windows Vista. Please help! Thank you!

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  • Including a List<SpecificType> in a model, and how to populate it

    - by Ray Sülzer
    I currently have two Model classes: class Leaders: List<Leaders> { public string LeaderName { get; set; } public string PrecintName { get; set; } } public class MarketReport { //A list of activists public Leaders leaderlist { get; set; } } Now, I have no idea if I am doing the above correctly, but I want to populate the list within the MarketReport foreach (var store in stores) { MarketReport.leaderlist.AddItem //I want to add an item of type Leader to the list //so that I can pass it to MVC view }

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  • Highlighting a custom UIButton

    - by Dan Ray
    The app I'm building has LOTS of custom UIButtons laying over top of fairly precisely laid out images. Buttonish, controllish images and labels and what have you, but with a clear custom-style UIButton sitting over top of it to handle the tap. My client yesterday says, "I want that to highlight when you tap it". Never mind that it immediately pushes on a new uinavigationcontroller view... it didn't blink, and so he's confused. Oy. Here's what I've done to address it. I don't like it, but it's what I've done: I subclassed UIButton (naming it FlashingUIButton). For some reason I couldn't just configure it with a background image on control mode highlighted. It never seemed to hit the state "highlighted". Don't know why that is. So instead I wrote: -(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { [self setBackgroundImage:[UIImage imageNamed:@"grey_screen"] forState:UIControlStateNormal]; [self performSelector:@selector(resetImage) withObject:nil afterDelay:0.2]; [super touchesBegan:touches withEvent:event]; } -(void)resetImage { [self setBackgroundImage:nil forState:UIControlStateNormal]; } This happily lays my grey_screen.png (a 30% opaque black box) over the button when it's tapped and replaces it with happy emptyness .2 of a second later. This is fine, but it means I have to go through all my many nibs and change all my buttons from UIButtons to FlashingUIButtons. Which isn't the end of the world, but I'd really hoped to address this as a UIButton category, and hit all birds with one stone. Any suggestions for a better approach than this one?

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  • How to know record has been updated successfully in php

    - by Lisa Ray
    $sql = "UPDATE...."; if(mysql_query($sql)) { $_SESSION['Trans']="COMMIT"; header("location:result.php"); exit; } else { $_SESSION['Trans']="FAIL"; $_SESSION['errors'] = "Error: Sorry! We are unable to update your Profile, Please contact to PNP HelpDesk."; header("location:result.php"); exit; }//end IF data is getting updated then why compiler is not coming inside IF condition.

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  • app engine's back referencing is too slow. How can I make it faster?

    - by Ray Yun
    Google app engine has smart feature named back references and I usually iterate them where the traditional SQL's computed column need to be used. Just imagine that need to accumulate specific force's total hp. class Force(db.Model): hp = db.IntegerProperty() class UnitGroup(db.Model): force = db.ReferenceProperty(reference_class=Force,collection_name="groups") hp = db.IntegerProperty() class Unit(db.Model): group = db.ReferenceProperty(reference_class=UnitGroup,collection_name="units") hp = db.IntegerProperty() When I code like following, it was horribly slow (almost 3s) with 20 forces with single group - single unit. (I guess back-referencing force reload sub entities. Am I right?) def get_hp(self): hp = 0 for group in self.groups: group_hp = 0 for unit in group.units: group_hp += unit.hp hp += group_hp return hp How can I optimize this code? Please consider that there are more properties should be computed for each force/unit-groups and I don't want to save these collective properties to each entities. :)

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  • How do I run my application while a UAC dialog window is showing?

    - by Ray
    I have an application that I wrote in .NET. It needs to remain running and have access the desktop that the UAC dialog windows open on and interact with that desktop using keyboard and mouse events. It's sort of like a VNC program. Imagine you are running a VNC program and a UAC window pops up, you want your VNC program to still be able to control the desktop with the UAC window in it so that the user can move the mouse and click the OK button on the UAC dialog. Can anyone tell me how I would go about doing that? Thanks

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  • javascript "window.history.forward(1);" not working.

    - by Ray L.
    Hi, I'm trying to prevent the back button from working on one of my asp.net mvc pages. I've read a couple of places that if i put "window.history.forward(1);" in my page it will prevent the back button from working on a given page. This is what I did in my page: <script type="text/javascript"> $(document).ready(function () { window.history.forward(1); }); </script> It doesn't seem to be working. Am I using this incorrectly or is this approach wrong? thanks.

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  • Mvc4 webapi file download with jquery

    - by Ray
    I want to download file on client side from api apicontroller: public HttpResponseMessage PostOfficeSupplies() { string csv = string.Format ("D:\\Others\\Images/file.png"); HttpResponseMessage result = new HttpResponseMessage(HttpStatusCode.OK); result.Content = new StringContent(csv); result.Content.Headers.ContentType = new MediaTypeHeaderValue ("application/octet-stream"); result.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment"); result.Content.Headers.ContentDisposition.FileName = "file.png"; return result; } 1.How can I popup a download with jquery(octet-stream) from api controller? my client side code: $(document).ready(function () { $.ajax( { url: 'api/MyAPI' , type: "post" , contentType: "application/octet-stream" , data: '' , success: function (retData) { $("body").append("<iframe src='" + retData + "' style='display: none;' ></iframe>"); } }); }); but it was not work!!!Thanks!!

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  • 3D coordinate of 2D point given camera and view plane

    - by Myx
    I wish to generate rays from the camera through the viewing plane. In order to do this, I need my camera position ("eye"), the up, right, and towards vectors (where towards is the vector from the camera in the direction of the object that the camera is looking at) and P, the point on the viewing plane. Once I have these, the ray that's generated is: ray = camera_eye + t*(P-camera_eye); where t is the distance along the ray (assume t = 1 for now). My question is, how do I obtain the 3D coordinates of point P given that it is located at position (i,j) on the viewing plane? Assume that the upper left and lower right corners of the viewing plane are given. NOTE: The viewing plane is not actually a plane in the sense that it doesn't extend infinitely in all directions. Rather, one may think of this plane as a widthxheight image. In the x direction, the range is 0--width and in the y direction the range is 0--height. I wish to find the 3D coordinate of the (i,j)th element, 0

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  • Using IF LARGE when there is text in column

    - by Ray
    I have an excel column of numbers and texts. I tried to use "IF LARGE" to find top 3 numbers of the column (A1 to A7), and return "Yes" to the cells right next to the top 3 (in column B). But unfortunately, the cells next to the texts also returned "Yes". This is the data: 0.2 0.3 Yes 0.5 Yes 0.1 0.8 Yes asdf Yes jklm Yes This is the code for cell B7: =IF(A7>=LARGE($A$1:$A$7,3),"Yes","") Any suggestions to fix this? thanks in advance

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  • Ten - oh, wait, eleven - Eleven things you should know about the ASP.NET Fall 2012 Update

    - by Jon Galloway
    Today, just a little over two months after the big ASP.NET 4.5 / ASP.NET MVC 4 / ASP.NET Web API / Visual Studio 2012 / Web Matrix 2 release, the first preview of the ASP.NET Fall 2012 Update is out. Here's what you need to know: There are no new framework bits in this release - there's no change or update to ASP.NET Core, ASP.NET MVC or Web Forms features. This means that you can start using it without any updates to your server, upgrade concerns, etc. This update is really an update to the project templates and Visual Studio tooling, conceptually similar to the ASP.NET MVC 3 Tools Update. It's a relatively lightweight install. It's a 41MB download. I've installed it many times and usually takes 5-7 minutes; it's never required a reboot. It adds some new project templates to ASP.NET MVC: Facebook Application and Single Page Application templates. It adds a lot of cool enhancements to ASP.NET Web API. It adds some tooling that makes it easy to take advantage of features like SignalR, Friendly URLs, and Windows Azure Authentication. Most of the new features are installed via NuGet packages. Since ASP.NET is open source, nightly NuGet packages are available, and the roadmap is published, most of this has really been publicly available for a while. The official name of this drop is the ASP.NET Fall 2012 Update BUILD Prerelease. Please do not attempt to say that ten times fast. While the EULA doesn't prohibit it, it WILL legally change your first name to Scott. As with all new releases, you can find out everything you need to know about the Fall Update at http://asp.net/vnext (especially the release notes!) I'm going to be showing all of this off, assisted by special guest code monkey Scott Hanselman, this Friday at BUILD: Bleeding edge ASP.NET: See what is next for MVC, Web API, SignalR and more… (and I've heard it will be livestreamed). Let's look at some of those things in more detail. No new bits ASP.NET 4.5, MVC 4 and Web API have a lot of great core features. I see the goal of this update release as making it easier to put those features to use to solve some useful scenarios by taking advantage of NuGet packages and template code. If you create a new ASP.NET MVC application using one of the new templates, you'll see that it's using the ASP.NET MVC 4 RTM NuGet package (4.0.20710.0): This means you can install and use the Fall Update without any impact on your existing projects and no worries about upgrading or compatibility. New Facebook Application Template ASP.NET MVC 4 (and ASP.NET 4.5 Web Forms) included the ability to authenticate your users via OAuth and OpenID, so you could let users log in to your site using a Facebook account. One of the new changes in the Fall Update is a new template that makes it really easy to create full Facebook applications. You could create Facebook application in ASP.NET already, you'd just need to go through a few steps: Search around to find a good Facebook NuGet package, like the Facebook C# SDK (written by my friend Nathan Totten and some other Facebook SDK brainiacs). Read the Facebook developer documentation to figure out how to authenticate and integrate with them. Write some code, debug it and repeat until you got something working. Get started with the application you'd originally wanted to write. What this template does for you: eliminate steps 1-3. Erik Porter, Nathan and some other experts built out the Facebook Application template so it automatically pulls in and configures the Facebook NuGet package and makes it really easy to take advantage of it in an ASP.NET MVC application. One great example is the the way you access a Facebook user's information. Take a look at the following code in a File / New / MVC / Facebook Application site. First, the Home Controller Index action: [FacebookAuthorize(Permissions = "email")] public ActionResult Index(MyAppUser user, FacebookObjectList<MyAppUserFriend> userFriends) { ViewBag.Message = "Modify this template to jump-start your Facebook application using ASP.NET MVC."; ViewBag.User = user; ViewBag.Friends = userFriends.Take(5); return View(); } First, notice that there's a FacebookAuthorize attribute which requires the user is authenticated via Facebook and requires permissions to access their e-mail address. It binds to two things: a custom MyAppUser object and a list of friends. Let's look at the MyAppUser code: using Microsoft.AspNet.Mvc.Facebook.Attributes; using Microsoft.AspNet.Mvc.Facebook.Models; // Add any fields you want to be saved for each user and specify the field name in the JSON coming back from Facebook // https://developers.facebook.com/docs/reference/api/user/ namespace MvcApplication3.Models { public class MyAppUser : FacebookUser { public string Name { get; set; } [FacebookField(FieldName = "picture", JsonField = "picture.data.url")] public string PictureUrl { get; set; } public string Email { get; set; } } } You can add in other custom fields if you want, but you can also just bind to a FacebookUser and it will automatically pull in the available fields. You can even just bind directly to a FacebookUser and check for what's available in debug mode, which makes it really easy to explore. For more information and some walkthroughs on creating Facebook applications, see: Deploying your first Facebook App on Azure using ASP.NET MVC Facebook Template (Yao Huang Lin) Facebook Application Template Tutorial (Erik Porter) Single Page Application template Early releases of ASP.NET MVC 4 included a Single Page Application template, but it was removed for the official release. There was a lot of interest in it, but it was kind of complex, as it handled features for things like data management. The new Single Page Application template that ships with the Fall Update is more lightweight. It uses Knockout.js on the client and ASP.NET Web API on the server, and it includes a sample application that shows how they all work together. I think the real benefit of this application is that it shows a good pattern for using ASP.NET Web API and Knockout.js. For instance, it's easy to end up with a mess of JavaScript when you're building out a client-side application. This template uses three separate JavaScript files (delivered via a Bundle, of course): todoList.js - this is where the main client-side logic lives todoList.dataAccess.js - this defines how the client-side application interacts with the back-end services todoList.bindings.js - this is where you set up events and overrides for the Knockout bindings - for instance, hooking up jQuery validation and defining some client-side events This is a fun one to play with, because you can just create a new Single Page Application and hit F5. Quick, easy install (with one gotcha) One of the cool engineering changes for this release is a big update to the installer to make it more lightweight and efficient. I've been running nightly builds of this for a few weeks to prep for my BUILD demos, and the install has been really quick and easy to use. The install takes about 5 minutes, has never required a reboot for me, and the uninstall is just as simple. There's one gotcha, though. In this preview release, you may hit an issue that will require you to uninstall and re-install the NuGet VSIX package. The problem comes up when you create a new MVC application and see this dialog: The solution, as explained in the release notes, is to uninstall and re-install the NuGet VSIX package: Start Visual Studio 2012 as an Administrator Go to Tools->Extensions and Updates and uninstall NuGet. Close Visual Studio Navigate to the ASP.NET Fall 2012 Update installation folder: For Visual Studio 2012: Program Files\Microsoft ASP.NET\ASP.NET Web Stack\Visual Studio 2012 For Visual Studio 2012 Express for Web: Program Files\Microsoft ASP.NET\ASP.NET Web Stack\Visual Studio Express 2012 for Web Double click on the NuGet.Tools.vsix to reinstall NuGet This took me under a minute to do, and I was up and running. ASP.NET Web API Update Extravaganza! Uh, the Web API team is out of hand. They added a ton of new stuff: OData support, Tracing, and API Help Page generation. OData support Some people like OData. Some people start twitching when you mention it. If you're in the first group, this is for you. You can add a [Queryable] attribute to an API that returns an IQueryable<Whatever> and you get OData query support from your clients. Then, without any extra changes to your client or server code, your clients can send filters like this: /Suppliers?$filter=Name eq ‘Microsoft’ For more information about OData support in ASP.NET Web API, see Alex James' mega-post about it: OData support in ASP.NET Web API ASP.NET Web API Tracing Tracing makes it really easy to leverage the .NET Tracing system from within your ASP.NET Web API's. If you look at the \App_Start\WebApiConfig.cs file in new ASP.NET Web API project, you'll see a call to TraceConfig.Register(config). That calls into some code in the new \App_Start\TraceConfig.cs file: public static void Register(HttpConfiguration configuration) { if (configuration == null) { throw new ArgumentNullException("configuration"); } SystemDiagnosticsTraceWriter traceWriter = new SystemDiagnosticsTraceWriter() { MinimumLevel = TraceLevel.Info, IsVerbose = false }; configuration.Services.Replace(typeof(ITraceWriter), traceWriter); } As you can see, this is using the standard trace system, so you can extend it to any other trace listeners you'd like. To see how it works with the built in diagnostics trace writer, just run the application call some API's, and look at the Visual Studio Output window: iisexpress.exe Information: 0 : Request, Method=GET, Url=http://localhost:11147/api/Values, Message='http://localhost:11147/api/Values' iisexpress.exe Information: 0 : Message='Values', Operation=DefaultHttpControllerSelector.SelectController iisexpress.exe Information: 0 : Message='WebAPI.Controllers.ValuesController', Operation=DefaultHttpControllerActivator.Create iisexpress.exe Information: 0 : Message='WebAPI.Controllers.ValuesController', Operation=HttpControllerDescriptor.CreateController iisexpress.exe Information: 0 : Message='Selected action 'Get()'', Operation=ApiControllerActionSelector.SelectAction iisexpress.exe Information: 0 : Operation=HttpActionBinding.ExecuteBindingAsync iisexpress.exe Information: 0 : Operation=QueryableAttribute.ActionExecuting iisexpress.exe Information: 0 : Message='Action returned 'System.String[]'', Operation=ReflectedHttpActionDescriptor.ExecuteAsync iisexpress.exe Information: 0 : Message='Will use same 'JsonMediaTypeFormatter' formatter', Operation=JsonMediaTypeFormatter.GetPerRequestFormatterInstance iisexpress.exe Information: 0 : Message='Selected formatter='JsonMediaTypeFormatter', content-type='application/json; charset=utf-8'', Operation=DefaultContentNegotiator.Negotiate iisexpress.exe Information: 0 : Operation=ApiControllerActionInvoker.InvokeActionAsync, Status=200 (OK) iisexpress.exe Information: 0 : Operation=QueryableAttribute.ActionExecuted, Status=200 (OK) iisexpress.exe Information: 0 : Operation=ValuesController.ExecuteAsync, Status=200 (OK) iisexpress.exe Information: 0 : Response, Status=200 (OK), Method=GET, Url=http://localhost:11147/api/Values, Message='Content-type='application/json; charset=utf-8', content-length=unknown' iisexpress.exe Information: 0 : Operation=JsonMediaTypeFormatter.WriteToStreamAsync iisexpress.exe Information: 0 : Operation=ValuesController.Dispose API Help Page When you create a new ASP.NET Web API project, you'll see an API link in the header: Clicking the API link shows generated help documentation for your ASP.NET Web API controllers: And clicking on any of those APIs shows specific information: What's great is that this information is dynamically generated, so if you add your own new APIs it will automatically show useful and up to date help. This system is also completely extensible, so you can generate documentation in other formats or customize the HTML help as much as you'd like. The Help generation code is all included in an ASP.NET MVC Area: SignalR SignalR is a really slick open source project that was started by some ASP.NET team members in their spare time to add real-time communications capabilities to ASP.NET - and .NET applications in general. It allows you to handle long running communications channels between your server and multiple connected clients using the best communications channel they can both support - websockets if available, falling back all the way to old technologies like long polling if necessary for old browsers. SignalR remains an open source project, but now it's being included in ASP.NET (also open source, hooray!). That means there's real, official ASP.NET engineering work being put into SignalR, and it's even easier to use in an ASP.NET application. Now in any ASP.NET project type, you can right-click / Add / New Item... SignalR Hub or Persistent Connection. And much more... There's quite a bit more. You can find more info at http://asp.net/vnext, and we'll be adding more content as fast as we can. Watch my BUILD talk to see as I demonstrate these and other features in the ASP.NET Fall 2012 Update, as well as some other even futurey-er stuff!

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  • Performance Optimization &ndash; It Is Faster When You Can Measure It

    - by Alois Kraus
    Performance optimization in bigger systems is hard because the measured numbers can vary greatly depending on the measurement method of your choice. To measure execution timing of specific methods in your application you usually use Time Measurement Method Potential Pitfalls Stopwatch Most accurate method on recent processors. Internally it uses the RDTSC instruction. Since the counter is processor specific you can get greatly different values when your thread is scheduled to another core or the core goes into a power saving mode. But things do change luckily: Intel's Designer's vol3b, section 16.11.1 "16.11.1 Invariant TSC The time stamp counter in newer processors may support an enhancement, referred to as invariant TSC. Processor's support for invariant TSC is indicated by CPUID.80000007H:EDX[8]. The invariant TSC will run at a constant rate in all ACPI P-, C-. and T-states. This is the architectural behavior moving forward. On processors with invariant TSC support, the OS may use the TSC for wall clock timer services (instead of ACPI or HPET timers). TSC reads are much more efficient and do not incur the overhead associated with a ring transition or access to a platform resource." DateTime.Now Good but it has only a resolution of 16ms which can be not enough if you want more accuracy.   Reporting Method Potential Pitfalls Console.WriteLine Ok if not called too often. Debug.Print Are you really measuring performance with Debug Builds? Shame on you. Trace.WriteLine Better but you need to plug in some good output listener like a trace file. But be aware that the first time you call this method it will read your app.config and deserialize your system.diagnostics section which does also take time.   In general it is a good idea to use some tracing library which does measure the timing for you and you only need to decorate some methods with tracing so you can later verify if something has changed for the better or worse. In my previous article I did compare measuring performance with quantum mechanics. This analogy does work surprising well. When you measure a quantum system there is a lower limit how accurately you can measure something. The Heisenberg uncertainty relation does tell us that you cannot measure of a quantum system the impulse and location of a particle at the same time with infinite accuracy. For programmers the two variables are execution time and memory allocations. If you try to measure the timings of all methods in your application you will need to store them somewhere. The fastest storage space besides the CPU cache is the memory. But if your timing values do consume all available memory there is no memory left for the actual application to run. On the other hand if you try to record all memory allocations of your application you will also need to store the data somewhere. This will cost you memory and execution time. These constraints are always there and regardless how good the marketing of tool vendors for performance and memory profilers are: Any measurement will disturb the system in a non predictable way. Commercial tool vendors will tell you they do calculate this overhead and subtract it from the measured values to give you the most accurate values but in reality it is not entirely true. After falling into the trap to trust the profiler timings several times I have got into the habit to Measure with a profiler to get an idea where potential bottlenecks are. Measure again with tracing only the specific methods to check if this method is really worth optimizing. Optimize it Measure again. Be surprised that your optimization has made things worse. Think harder Implement something that really works. Measure again Finished! - Or look for the next bottleneck. Recently I have looked into issues with serialization performance. For serialization DataContractSerializer was used and I was not sure if XML is really the most optimal wire format. After looking around I have found protobuf-net which uses Googles Protocol Buffer format which is a compact binary serialization format. What is good for Google should be good for us. A small sample app to check out performance was a matter of minutes: using ProtoBuf; using System; using System.Diagnostics; using System.IO; using System.Reflection; using System.Runtime.Serialization; [DataContract, Serializable] class Data { [DataMember(Order=1)] public int IntValue { get; set; } [DataMember(Order = 2)] public string StringValue { get; set; } [DataMember(Order = 3)] public bool IsActivated { get; set; } [DataMember(Order = 4)] public BindingFlags Flags { get; set; } } class Program { static MemoryStream _Stream = new MemoryStream(); static MemoryStream Stream { get { _Stream.Position = 0; _Stream.SetLength(0); return _Stream; } } static void Main(string[] args) { DataContractSerializer ser = new DataContractSerializer(typeof(Data)); Data data = new Data { IntValue = 100, IsActivated = true, StringValue = "Hi this is a small string value to check if serialization does work as expected" }; var sw = Stopwatch.StartNew(); int Runs = 1000 * 1000; for (int i = 0; i < Runs; i++) { //ser.WriteObject(Stream, data); Serializer.Serialize<Data>(Stream, data); } sw.Stop(); Console.WriteLine("Did take {0:N0}ms for {1:N0} objects", sw.Elapsed.TotalMilliseconds, Runs); Console.ReadLine(); } } The results are indeed promising: Serializer Time in ms N objects protobuf-net   807 1000000 DataContract 4402 1000000 Nearly a factor 5 faster and a much more compact wire format. Lets use it! After switching over to protbuf-net the transfered wire data has dropped by a factor two (good) and the performance has worsened by nearly a factor two. How is that possible? We have measured it? Protobuf-net is much faster! As it turns out protobuf-net is faster but it has a cost: For the first time a type is de/serialized it does use some very smart code-gen which does not come for free. Lets try to measure this one by setting of our performance test app the Runs value not to one million but to 1. Serializer Time in ms N objects protobuf-net 85 1 DataContract 24 1 The code-gen overhead is significant and can take up to 200ms for more complex types. The break even point where the code-gen cost is amortized by its faster serialization performance is (assuming small objects) somewhere between 20.000-40.000 serialized objects. As it turned out my specific scenario involved about 100 types and 1000 serializations in total. That explains why the good old DataContractSerializer is not so easy to take out of business. The final approach I ended up was to reduce the number of types and to serialize primitive types via BinaryWriter directly which turned out to be a pretty good alternative. It sounded good until I measured again and found that my optimizations so far do not help much. After looking more deeper at the profiling data I did found that one of the 1000 calls did take 50% of the time. So how do I find out which call it was? Normal profilers do fail short at this discipline. A (totally undeserved) relatively unknown profiler is SpeedTrace which does unlike normal profilers create traces of your applications by instrumenting your IL code at runtime. This way you can look at the full call stack of the one slow serializer call to find out if this stack was something special. Unfortunately the call stack showed nothing special. But luckily I have my own tracing as well and I could see that the slow serializer call did happen during the serialization of a bool value. When you encounter after much analysis something unreasonable you cannot explain it then the chances are good that your thread was suspended by the garbage collector. If there is a problem with excessive GCs remains to be investigated but so far the serialization performance seems to be mostly ok.  When you do profile a complex system with many interconnected processes you can never be sure that the timings you just did measure are accurate at all. Some process might be hitting the disc slowing things down for all other processes for some seconds as well. There is a big difference between warm and cold startup. If you restart all processes you can basically forget the first run because of the OS disc cache, JIT and GCs make the measured timings very flexible. When you are in need of a random number generator you should measure cold startup times of a sufficiently complex system. After the first run you can try again getting different and much lower numbers. Now try again at least two times to get some feeling how stable the numbers are. Oh and try to do the same thing the next day. It might be that the bottleneck you found yesterday is gone today. Thanks to GC and other random stuff it can become pretty hard to find stuff worth optimizing if no big bottlenecks except bloatloads of code are left anymore. When I have found a spot worth optimizing I do make the code changes and do measure again to check if something has changed. If it has got slower and I am certain that my change should have made it faster I can blame the GC again. The thing is that if you optimize stuff and you allocate less objects the GC times will shift to some other location. If you are unlucky it will make your faster working code slower because you see now GCs at times where none were before. This is where the stuff does get really tricky. A safe escape hatch is to create a repro of the slow code in an isolated application so you can change things fast in a reliable manner. Then the normal profilers do also start working again. As Vance Morrison does point out it is much more complex to profile a system against the wall clock compared to optimize for CPU time. The reason is that for wall clock time analysis you need to understand how your system does work and which threads (if you have not one but perhaps 20) are causing a visible delay to the end user and which threads can wait a long time without affecting the user experience at all. Next time: Commercial profiler shootout.

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  • Using ethernet cables?

    - by Farhad Yusufali
    I have an HDTV which supports internet connectivity through an ethernet port or wirelessly (but this requires an additional wireless USB adapter, which I don't have). I also have a blue ray player than supports internet connectivity through an ethernet port or wirelessly (natively - no other devices are needed). I want to connect my TV to the internet but my router is too far away. My blueray player however is already connected wirelessly. If I connected my TV to my Blueray player via ethernet, would my TV be able to connect to the internet? To clarify: Wireless Signal - Blue Ray Player - Ethernet Cable - TV Would this work?

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  • I/O Error with PHP5-FPM, ptrace(PEEKDATA) failed

    - by MultiformeIngegno
    I got a lot of these: [NOTICE] child 19214 stopped for tracing [NOTICE] about to trace 19214 [ERROR] ptrace(PEEKDATA) failed: Input/output error (5) [NOTICE] finished trace of 19214 [WARNING] [pool www] child 19208, script 'blahblah.php' executing too slow (30.041419 sec), logging [NOTICE] child 19208 stopped for tracing [NOTICE] about to trace 19208 [ERROR] ptrace(PEEKDATA) failed: Input/output error (5) [NOTICE] finished trace of 19208 [WARNING] [pool www] child 19218, script 'blahblah.php' executing too slow (30.035029 sec), logging And when php reaches max children (at least I presume that's the case) it stops "working"... now I know I can increase max_children (currently set to 9) but there's a way to stop php from "dying"? I'm on a VPS with 1 core and 512 MB of RAM (PHP5-FPM 5.4.4 + APC 3.1.10).

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  • Screen space to world space

    - by user13414
    I am writing a 2D game where my game world has x axis running left to right, y axis running top to bottom, and z axis out of the screen: Whilst my game world is top-down, the game is rendered on a slight tilt: I'm working on projecting from world space to screen space, and vice-versa. I have the former working as follows: var viewport = new Viewport(0, 0, this.ScreenWidth, this.ScreenHeight); var screenPoint = viewport.Project(worldPoint.NegateY(), this.ProjectionMatrix, this.ViewMatrix, this.WorldMatrix); The NegateY() extension method does exactly what it sounds like, since XNA's y axis runs bottom to top instead of top to bottom. The screenshot above shows this all working. Basically, I have a bunch of points in 3D space that I then render in screen space. I can modify camera properties in real time and see it animate to the new position. Obviously my actual game will use sprites rather than points and the camera position will be fixed, but I'm just trying to get all the math in place before getting to that. Now, I am trying to convert back the other way. That is, given an x and y point in screen space above, determine the corresponding point in world space. So if I point the cursor at, say, the bottom-left of the green trapezoid, I want to get a world space reading of (0, 480). The z coordinate is irrelevant. Or, rather, the z coordinate will always be zero when mapping back to world space. Essentially, I want to implement this method signature: public Vector2 ScreenPointToWorld(Vector2 point) I've tried several things to get this working but am just having no luck. My latest thinking is that I need to call Viewport.Unproject twice with differing near/far z values, calculate the resultant Ray, normalize it, then calculate the intersection of the Ray with a Plane that basically represents ground-level of my world. However, I got stuck on the last step and wasn't sure whether I was over-complicating things. Can anyone point me in the right direction on how to achieve this?

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  • How do I get VDPAU working with Ubuntu 9.1?

    - by Brad Robertson
    What do I need to do to get MKV HD videos playing with VDPAU and also Blu-ray discs? Lots of people say you need to compile the latest MPlayer (which I haven't had luck doing) for VDPAU. I found an mplayer ppa that says it has VDPAU compiled into it so I'd like to use that. What packages do I need for playing MKV files and Blu-ray with the video decoding offloaded to my GPU? So far I haven't had any luck with any of the tutorials I've found. I'm just looking for a quick synopsis that will tell me what I'm looking for as I'm kind of shooting in the dark. (I didn't know what VDPAU was until a few days ago.)

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  • Java ME SDK 3.0.5 is released!

    - by SungmoonCho
      Java ME SDK 3.0.5 went live! For many months, we have been working hard to fix bugs from previous version, and add a lot of new features demanded by Java ME community. You can download the new version from this link. Please see below for more information. NetBeans Integration All Java ME tools are implemented as NetBeans plugins. Device Manager Java ME SDK now supports multiple device managers. You can switch between different versions of device managers. LWUIT 1.5 Support The Resource Editor is available from the Java ME menu to help you design and organize resources for LWUIT applications. For a description of LWUIT 1.5 features, visit the LWUIT download page Network Monitor Integrated with NetBeans profiling tools, the Network Monitor now supports WMA, SIP, Bluetooth and OBEX, SATSA APDU and JCRMI, and server sockets. CPU Profiler Now uses standard NetBeans profiling facilities to view snapshots. Profiling of VM classes can also be toggled on or off. WURFL Device Database The database has been updated with more than 1000 new devices. Tracing - New tracing functionality now includes CLDC VM events, and monitors events such as exceptions, class loading, garbage collection, and methods invocation. New or updated JSR support - Includes support for JSR 234 (Advanced Multimedia Supplements), JSR 253 (Mobile Telephony API), JSR 257 (Contactless Communication API), JSR 258 (Mobile User Interface Customization API), and JSR 293 (XML API for Java ME).

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