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  • Installing mod_mono on Ubuntu: handler doesn't seem to get registered

    - by Trevor Johns
    I'm trying to install mod_mono on Apache 2 (Prefork MPM). I'm using Ubuntu Karmic, and just want an auto-hosting setup (so that any .aspx files are executed, similar to how PHP is normally setup). I did the following to install Mono: $ apt-get install libapache2-mod-mono mono-apache-server2 mono-devel $ a2dismod mod_mono $ a2enmod mod_mono_auto I've confirmed that mod_mono is getting loaded by Apache. However, any .aspx pages I try to load are returned unprocessed and still have an application/x-asp-net MIME type. It's as if the mod_mono handler never gets registered with Apache. Here's the contents of /etc/mod_mono_auto.load: LoadModule mono_module /usr/lib/apache2/modules/mod_mono.so And here's /etc/mod_mono_auto.conf: MonoAutoApplication enabled AddType application/x-asp-net .aspx AddType application/x-asp-net .asmx AddType application/x-asp-net .ashx AddType application/x-asp-net .asax AddType application/x-asp-net .ascx AddType application/x-asp-net .soap AddType application/x-asp-net .rem AddType application/x-asp-net .axd AddType application/x-asp-net .cs AddType application/x-asp-net .config AddType application/x-asp-net .dll DirectoryIndex index.aspx DirectoryIndex Default.aspx DirectoryIndex default.aspx I've even tried setting the handler explicitly: AddHandler mono .aspx .ascx .asax .ashx .config .cs .asmx .asp Nothing seems to help. Any ideas how to get this working?

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  • Adding Unobtrusive Validation To MVCContrib Fluent Html

    - by srkirkland
    ASP.NET MVC 3 includes a new unobtrusive validation strategy that utilizes HTML5 data-* attributes to decorate form elements.  Using a combination of jQuery validation and an unobtrusive validation adapter script that comes with MVC 3, those attributes are then turned into client side validation rules. A Quick Introduction to Unobtrusive Validation To quickly show how this works in practice, assume you have the following Order.cs class (think Northwind) [If you are familiar with unobtrusive validation in MVC 3 you can skip to the next section]: public class Order : DomainObject { [DataType(DataType.Date)] public virtual DateTime OrderDate { get; set; }   [Required] [StringLength(12)] public virtual string ShipAddress { get; set; }   [Required] public virtual Customer OrderedBy { get; set; } } .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; } Note the System.ComponentModel.DataAnnotations attributes, which provide the validation and metadata information used by ASP.NET MVC 3 to determine how to render out these properties.  Now let’s assume we have a form which can edit this Order class, specifically let’s look at the ShipAddress property: @Html.LabelFor(x => x.Order.ShipAddress) @Html.EditorFor(x => x.Order.ShipAddress) @Html.ValidationMessageFor(x => x.Order.ShipAddress) .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; } Now the Html.EditorFor() method is smart enough to look at the ShipAddress attributes and write out the necessary unobtrusive validation html attributes.  Note we could have used Html.TextBoxFor() or even Html.TextBox() and still retained the same results. If we view source on the input box generated by the Html.EditorFor() call, we get the following: <input type="text" value="Rua do Paço, 67" name="Order.ShipAddress" id="Order_ShipAddress" data-val-required="The ShipAddress field is required." data-val-length-max="12" data-val-length="The field ShipAddress must be a string with a maximum length of 12." data-val="true" class="text-box single-line input-validation-error"> .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; } As you can see, we have data-val-* attributes for both required and length, along with the proper error messages and additional data as necessary (in this case, we have the length-max=”12”). And of course, if we try to submit the form with an invalid value, we get an error on the client: Working with MvcContrib’s Fluent Html The MvcContrib project offers a fluent interface for creating Html elements which I find very expressive and useful, especially when it comes to creating select lists.  Let’s look at a few quick examples: @this.TextBox(x => x.FirstName).Class("required").Label("First Name:") @this.MultiSelect(x => x.UserId).Options(ViewModel.Users) @this.CheckBox("enabled").LabelAfter("Enabled").Title("Click to enable.").Styles(vertical_align => "middle")   @(this.Select("Order.OrderedBy").Options(Model.Customers, x => x.Id, x => x.CompanyName) .Selected(Model.Order.OrderedBy != null ? Model.Order.OrderedBy.Id : "") .FirstOption(null, "--Select A Company--") .HideFirstOptionWhen(Model.Order.OrderedBy != null) .Label("Ordered By:")) .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; } These fluent html helpers create the normal html you would expect, and I think they make life a lot easier and more readable when dealing with complex markup or select list data models (look ma: no anonymous objects for creating class names!). Of course, the problem we have now is that MvcContrib’s fluent html helpers don’t know about ASP.NET MVC 3’s unobtrusive validation attributes and thus don’t take part in client validation on your page.  This is not ideal, so I wrote a quick helper method to extend fluent html with the knowledge of what unobtrusive validation attributes to include when they are rendered. Extending MvcContrib’s Fluent Html Before posting the code, there are just a few things you need to know.  The first is that all Fluent Html elements implement the IElement interface (MvcContrib.FluentHtml.Elements.IElement), and the second is that the base System.Web.Mvc.HtmlHelper has been extended with a method called GetUnobtrusiveValidationAttributes which we can use to determine the necessary attributes to include.  With this knowledge we can make quick work of extending fluent html: public static class FluentHtmlExtensions { public static T IncludeUnobtrusiveValidationAttributes<T>(this T element, HtmlHelper htmlHelper) where T : MvcContrib.FluentHtml.Elements.IElement { IDictionary<string, object> validationAttributes = htmlHelper .GetUnobtrusiveValidationAttributes(element.GetAttr("name"));   foreach (var validationAttribute in validationAttributes) { element.SetAttr(validationAttribute.Key, validationAttribute.Value); }   return element; } } .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 code is pretty straight forward – basically we use a passed HtmlHelper to get a list of validation attributes for the current element and then add each of the returned attributes to the element to be rendered. The Extension In Action Now let’s get back to the earlier ShipAddress example and see what we’ve accomplished.  First we will use a fluent html helper to render out the ship address text input (this is the ‘before’ case): @this.TextBox("Order.ShipAddress").Label("Ship Address:").Class("class-name") .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; } And the resulting HTML: <label id="Order_ShipAddress_Label" for="Order_ShipAddress">Ship Address:</label> <input type="text" value="Rua do Paço, 67" name="Order.ShipAddress" id="Order_ShipAddress" class="class-name"> Now let’s do the same thing except here we’ll use the newly written extension method: @this.TextBox("Order.ShipAddress").Label("Ship Address:") .Class("class-name").IncludeUnobtrusiveValidationAttributes(Html) .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; } And the resulting HTML: <label id="Order_ShipAddress_Label" for="Order_ShipAddress">Ship Address:</label> <input type="text" value="Rua do Paço, 67" name="Order.ShipAddress" id="Order_ShipAddress" data-val-required="The ShipAddress field is required." data-val-length-max="12" data-val-length="The field ShipAddress must be a string with a maximum length of 12." data-val="true" class="class-name"> .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; } Excellent!  Now we can continue to use unobtrusive validation and have the flexibility to use ASP.NET MVC’s Html helpers or MvcContrib’s fluent html helpers interchangeably, and every element will participate in client side validation. Wrap Up Overall I’m happy with this solution, although in the best case scenario MvcContrib would know about unobtrusive validation attributes and include them automatically (of course if it is enabled in the web.config file).  I know that MvcContrib allows you to author global behaviors, but that requires changing the base class of your views, which I am not willing to do. Enjoy!

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  • Asp.net tips and tricks

    - by ybbest
    Asp.net tips and tricks Here is a summary of articles I found very useful over the years while I am working on asp.net TRULY Understanding View state http://weblogs.asp.net/infinitiesloop/archive/2006/08/03/Truly-Understanding-Viewstate.aspx TRULY Understanding Dynamic Controls http://weblogs.asp.net/infinitiesloop/archive/2006/08/25/TRULY-Understanding-Dynamic-Controls-_2800_Part-1_2900_.aspx ASP.Net 2.0 – Master Pages: Tips, Tricks, and Traps http://odetocode.com/articles/450.aspx ASP.NET Tip – Use The Label Control Correctly http://haacked.com/archive/2007/02/15/asp.net_tip_-_use_the_label_control_correctly.aspx Asp.net httphandlers http://www.michaelflanakin.com/Articles/NET/NET1x/ImplementingHTTPHandlers/tabid/173/Default.aspx http://support.microsoft.com/default.aspx?scid=kb;EN-US;308001 http://msdn.microsoft.com/en-us/library/ms972974.aspx Asp.net ajax http://encosia.com/ ASP.NET 2.0 Tips, Tricks, Recipes and Gotchas http://weblogs.asp.net/scottgu/pages/ASP.NET-2.0-Tips_2C00_-Tricks_2C00_-Recipes-and-Gotchas.aspx Mastering Page-UserControl Communication http://www.codeproject.com/KB/user-controls/Page_UserControl.aspx Comparing Web Site Projects and Web Application Projects Web Deployment Projects .NET Radio Show http://www.dotnetrocks.com/ Herdingcode http://herdingcode.com/ Clean Code talk http://www.objectmentor.com/videos/video_index.html .NET Video Show http://www.dnrtv.com/ .Net User group http://chicagoalt.net/home http://exposureroom.com/members/RIAViewMirror.aspx/assets/ FAQ Why should you remove unnecessary C# using directives? http://stackoverflow.com/questions/136278/why-should-you-remove-unnecessary-c-using-directives http://stackoverflow.com/questions/2009471/what-is-the-benefit-of-removing-redundant-imports-in-vb-net-or-using-in-c-file http://codeclimber.net.nz/archive/2009/12/30/best-of-2009-the-5-most-popular-posts.aspx

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  • The best way to learn how to extend Orchard

    - by Bertrand Le Roy
    We do have tutorials on the Orchard site, but we can't cover all topics, and recently I've found myself more and more responding to forum questions by pointing people to an existing module that was solving a similar problem to the one the question was about. I really like this way of learning by example and from the expertise of others. This is one of the reasons why we decided that modules would by default come in source code form that we compile dynamically. it makes them easy to understand and easier to modify for your own purposes. Hackability FTW! But how do you crack open a module and look at what's inside? You can do it in two different ways. First, you can just install the module from the gallery, directly from your Orchard instance's admin panel. Once you've done that, you can just look into your Modules directory under the web site. There is now a subfolder with the name of the new module that contains a csproj that you can open in Visual Studio or add to your Orchard solution. Second, you can simply download the package (it's NuGet) and rename it to a .zip extension. NuGet being based on Zip, this will open just fine in Windows Explorer: What you want to dig into is the Content/Modules/[NameOfTheModule] folder, which is where the actual code is. Thanks to Jason Gaylord for the idea for this post.

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  • Update Rule in Temporal difference

    - by Betamoo
    The update rule TD(0) Q-Learning: Q(t-1) = (1-alpha) * Q(t-1) + (alpha) * (Reward(t-1) + gamma* Max( Q(t) ) ) Then take either the current best action (to optimize) or a random action (to explorer) Where MaxNextQ is the maximum Q that can be got in the next state... But in TD(1) I think update rule will be: Q(t-2) = (1-alpha) * Q(t-2) + (alpha) * (Reward(t-2) + gamma * Reward(t-1) + gamma * gamma * Max( Q(t) ) ) My question: The term gamma * Reward(t-1) means that I will always take my best action at t-1 .. which I think will prevent exploring.. Can someone give me a hint? Thanks

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  • Displaying an image on a LED matrix with a Netduino

    - by Bertrand Le Roy
    In the previous post, we’ve been flipping bits manually on three ports of the Netduino to simulate the data, clock and latch pins that a shift register expected. We did all that in order to control one line of a LED matrix and create a simple Knight Rider effect. It was rightly pointed out in the comments that the Netduino has built-in knowledge of the sort of serial protocol that this shift register understands through a feature called SPI. That will of course make our code a whole lot simpler, but it will also make it a whole lot faster: writing to the Netduino ports is actually not that fast, whereas SPI is very, very fast. Unfortunately, the Netduino documentation for SPI is severely lacking. Instead, we’ve been reliably using the documentation for the Fez, another .NET microcontroller. To send data through SPI, we’ll just need  to move a few wires around and update the code. SPI uses pin D11 for writing, pin D12 for reading (which we won’t do) and pin D13 for the clock. The latch pin is a parameter that can be set by the user. This is very close to the wiring we had before (data on D11, clock on D12 and latch on D13). We just have to move the latch from D13 to D10, and the clock from D12 to D13. The code that controls the shift register has slimmed down considerably with that change. Here is the new version, which I invite you to compare with what we had before: public class ShiftRegister74HC595 { protected SPI Spi; public ShiftRegister74HC595(Cpu.Pin latchPin) : this(latchPin, SPI.SPI_module.SPI1) { } public ShiftRegister74HC595(Cpu.Pin latchPin, SPI.SPI_module spiModule) { var spiConfig = new SPI.Configuration( SPI_mod: spiModule, ChipSelect_Port: latchPin, ChipSelect_ActiveState: false, ChipSelect_SetupTime: 0, ChipSelect_HoldTime: 0, Clock_IdleState: false, Clock_Edge: true, Clock_RateKHz: 1000 ); Spi = new SPI(spiConfig); } public void Write(byte buffer) { Spi.Write(new[] {buffer}); } } All we have to do here is configure SPI. The write method couldn’t be any simpler. Everything is now handled in hardware by the Netduino. We set the frequency to 1MHz, which is largely sufficient for what we’ll be doing, but it could potentially go much higher. The shift register addresses the columns of the matrix. The rows are directly wired to ports D0 to D7 of the Netduino. The code writes to only one of those eight lines at a time, which will make it fast enough. The way an image is displayed is that we light the lines one after the other so fast that persistence of vision will give the illusion of a stable image: foreach (var bitmap in matrix.MatrixBitmap) { matrix.OnRow(row, bitmap, true); matrix.OnRow(row, bitmap, false); row++; } Now there is a twist here: we need to run this code as fast as possible in order to display the image with as little flicker as possible, but we’ll eventually have other things to do. In other words, we need the code driving the display to run in the background, except when we want to change what’s being displayed. Fortunately, the .NET Micro Framework supports multithreading. In our implementation, we’ve added an Initialize method that spins a new thread that is tied to the specific instance of the matrix it’s being called on. public LedMatrix Initialize() { DisplayThread = new Thread(() => DoDisplay(this)); DisplayThread.Start(); return this; } I quite like this way to spin a thread. As you may know, there is another, built-in way to contextualize a thread by passing an object into the Start method. For the method to work, the thread must have been constructed with a ParameterizedThreadStart delegate, which takes one parameter of type object. I like to use object as little as possible, so instead I’m constructing a closure with a Lambda, currying it with the current instance. This way, everything remains strongly-typed and there’s no casting to do. Note that this method would extend perfectly to several parameters. Of note as well is the return value of Initialize, a common technique to add some fluency to the API and enabling the matrix to be instantiated and initialized in a single line: using (var matrix = new LedMS88SR74HC595().Initialize()) The “using” in the previous line is because we have implemented IDisposable so that the matrix kills the thread and clears the display when the user code is done with it: public void Dispose() { Clear(); DisplayThread.Abort(); } Thanks to the multi-threaded version of the matrix driver class, we can treat the display as a simple bitmap with a very synchronous programming model: matrix.Set(someimage); while (button.Read()) { Thread.Sleep(10); } Here, the call into Set returns immediately and from the moment the bitmap is set, the background display thread will constantly continue refreshing no matter what happens in the main thread. That enables us to wait or read a button’s port on the main thread knowing that the current image will continue displaying unperturbed and without requiring manual refreshing. We’ve effectively hidden the implementation of the display behind a convenient, synchronous-looking API. Pretty neat, eh? Before I wrap up this post, I want to talk about one small caveat of using SPI rather than driving the shift register directly: when we got to the point where we could actually display images, we noticed that they were a mirror image of what we were sending in. Oh noes! Well, the reason for it is that SPI is sending the bits in a big-endian fashion, in other words backwards. Now sure you could fix that in software by writing some bit-level code to reverse the bits we’re sending in, but there is a far more efficient solution than that. We are doing hardware here, so we can simply reverse the order in which the outputs of the shift register are connected to the columns of the matrix. That’s switching 8 wires around once, as compared to doing bit operations every time we send a line to display. All right, so bringing it all together, here is the code we need to write to display two images in succession, separated by a press on the board’s button: var button = new InputPort(Pins.ONBOARD_SW1, false, Port.ResistorMode.Disabled); using (var matrix = new LedMS88SR74HC595().Initialize()) { // Oh, prototype is so sad! var sad = new byte[] { 0x66, 0x24, 0x00, 0x18, 0x00, 0x3C, 0x42, 0x81 }; DisplayAndWait(sad, matrix, button); // Let's make it smile! var smile = new byte[] { 0x42, 0x18, 0x18, 0x81, 0x7E, 0x3C, 0x18, 0x00 }; DisplayAndWait(smile, matrix, button); } And here is a video of the prototype running: The prototype in action I’ve added an artificial delay between the display of each row of the matrix to clearly show what’s otherwise happening very fast. This way, you can clearly see each of the two images being displayed line by line. Next time, we’ll do no hardware changes, focusing instead on building a nice programming model for the matrix, with sprites, text and hardware scrolling. Fun stuff. By the way, can any of my reader guess where we’re going with all that? The code for this prototype can be downloaded here: http://weblogs.asp.net/blogs/bleroy/Samples/NetduinoLedMatrixDriver.zip

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  • Tulsa SharePoint Interest Group – Meeting Reminder

    - by dmccollough
    Just a quick reminder that the Tulsa SharePoint Interest Group is having it’s monthly meeting this coming Monday April 12th @6:00 PM.   Please come see Corey Roth’s presentation on SharePoint 2010 Business Connectivity Services   We are going to be giving away some GREAT prizes XBox 360 – Halo 3 ODST Telerik Premium Collection ($1,300.00 value) ReSharper ($199.00 value) SQL Sets ($149.00 value) 64 Bit Windows 7 Infragistics NetAdvantage for .NET Platform ($1,195.00 value) You can click here for more information. You can click here to RSVP for the meeting.

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  • Speaking at Microsoft's Duth DevDays

    - by gsusx
    Last week I had the pleasure of presenting two sessions at Microsoft's Dutch DevDays at Den Hague. On Tuesday I presented a sessions about how to implement real world RESTFul services patterns using WCF, WCF Data Services and ASP.NET MVC2. During that session I showed a total of 15 small demos that highlighted how to implement key aspects of RESTful solutions such as Security, LowREST clients, URI modeling, Validation, Error Handling, etc. As part of those demos I used the OAuth implementation created...(read more)

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  • Using delegates in C# (Part 2)

    - by rajbk
    Part 1 of this post can be read here. We are now about to see the different syntaxes for invoking a delegate and some c# syntactic sugar which allows you to code faster. We have the following console application. 1: public delegate double Operation(double x, double y); 2:  3: public class Program 4: { 5: [STAThread] 6: static void Main(string[] args) 7: { 8: Operation op1 = new Operation(Division); 9: double result = op1.Invoke(10, 5); 10: 11: Console.WriteLine(result); 12: Console.ReadLine(); 13: } 14: 15: static double Division(double x, double y) { 16: return x / y; 17: } 18: } Line 1 defines a delegate type called Operation with input parameters (double x, double y) and a return type of double. On Line 8, we create an instance of this delegate and set the target to be a static method called Division (Line 15) On Line 9, we invoke the delegate (one entry in the invocation list). The program outputs 5 when run. The language provides shortcuts for creating a delegate and invoking it (see line 9 and 11). Line 9 is a syntactical shortcut for creating an instance of the Delegate. The C# compiler will infer on its own what the delegate type is and produces intermediate language that creates a new instance of that delegate. Line 11 uses a a syntactical shortcut for invoking the delegate by removing the Invoke method. The compiler sees the line and generates intermediate language which invokes the delegate. When this code is compiled, the generated IL will look exactly like the IL of the compiled code above. 1: public delegate double Operation(double x, double y); 2:  3: public class Program 4: { 5: [STAThread] 6: static void Main(string[] args) 7: { 8: //shortcut constructor syntax 9: Operation op1 = Division; 10: //shortcut invoke syntax 11: double result = op1(10, 2); 12: 13: Console.WriteLine(result); 14: Console.ReadLine(); 15: } 16: 17: static double Division(double x, double y) { 18: return x / y; 19: } 20: } C# 2.0 introduced Anonymous Methods. Anonymous methods avoid the need to create a separate method that contains the same signature as the delegate type. Instead you write the method body in-line. There is an interesting fact about Anonymous methods and closures which won’t be covered here. Use your favorite search engine ;-)We rewrite our code to use anonymous methods (see line 9): 1: public delegate double Operation(double x, double y); 2:  3: public class Program 4: { 5: [STAThread] 6: static void Main(string[] args) 7: { 8: //Anonymous method 9: Operation op1 = delegate(double x, double y) { 10: return x / y; 11: }; 12: double result = op1(10, 2); 13: 14: Console.WriteLine(result); 15: Console.ReadLine(); 16: } 17: 18: static double Division(double x, double y) { 19: return x / y; 20: } 21: } We could rewrite our delegate to be of a generic type like so (see line 2 and line 9). You will see why soon. 1: //Generic delegate 2: public delegate T Operation<T>(T x, T y); 3:  4: public class Program 5: { 6: [STAThread] 7: static void Main(string[] args) 8: { 9: Operation<double> op1 = delegate(double x, double y) { 10: return x / y; 11: }; 12: double result = op1(10, 2); 13: 14: Console.WriteLine(result); 15: Console.ReadLine(); 16: } 17: 18: static double Division(double x, double y) { 19: return x / y; 20: } 21: } The .NET 3.5 framework introduced a whole set of predefined delegates for us including public delegate TResult Func<T1, T2, TResult>(T1 arg1, T2 arg2); Our code can be modified to use this delegate instead of the one we declared. Our delegate declaration has been removed and line 7 has been changed to use the Func delegate type. 1: public class Program 2: { 3: [STAThread] 4: static void Main(string[] args) 5: { 6: //Func is a delegate defined in the .NET 3.5 framework 7: Func<double, double, double> op1 = delegate (double x, double y) { 8: return x / y; 9: }; 10: double result = op1(10, 2); 11: 12: Console.WriteLine(result); 13: Console.ReadLine(); 14: } 15: 16: static double Division(double x, double y) { 17: return x / y; 18: } 19: } .NET 3.5 also introduced lambda expressions. A lambda expression is an anonymous function that can contain expressions and statements, and can be used to create delegates or expression tree types. We change our code to use lambda expressions. 1: public class Program 2: { 3: [STAThread] 4: static void Main(string[] args) 5: { 6: //lambda expression 7: Func<double, double, double> op1 = (x, y) => x / y; 8: double result = op1(10, 2); 9: 10: Console.WriteLine(result); 11: Console.ReadLine(); 12: } 13: 14: static double Division(double x, double y) { 15: return x / y; 16: } 17: } C# 3.0 introduced the keyword var (implicitly typed local variable) where the type of the variable is inferred based on the type of the associated initializer expression. We can rewrite our code to use var as shown below (line 7).  The implicitly typed local variable op1 is inferred to be a delegate of type Func<double, double, double> at compile time. 1: public class Program 2: { 3: [STAThread] 4: static void Main(string[] args) 5: { 6: //implicitly typed local variable 7: var op1 = (x, y) => x / y; 8: double result = op1(10, 2); 9: 10: Console.WriteLine(result); 11: Console.ReadLine(); 12: } 13: 14: static double Division(double x, double y) { 15: return x / y; 16: } 17: } You have seen how we can write code in fewer lines by using a combination of the Func delegate type, implicitly typed local variables and lambda expressions.

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  • EF 4’s PluralizationService Class: A Singularly Impossible Plurality

    - by Ken Cox [MVP]
    Entity Framework’s new 4.0 designer does its best to generate correct plural and singular forms of object names. This magic is done through the PluralizationService Class found in the System.Data.Entity.Design.PluralizationServices namespace and in the System.Data.Entity.Design.dll assembly. [Before you ask… Yes, I’ll post my example page, the service, and the project source code as soon as my ISP makes ASP.NET 4 RTM available. Stay tuned.] Anyone who speaks English is brutally aware of the ridiculous...(read more)

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  • Using MAC Authentication for simple Web API’s consumption

    - by cibrax
    For simple scenarios of Web API consumption where identity delegation is not required, traditional http authentication schemas such as basic, certificates or digest are the most used nowadays. All these schemas rely on sending the caller credentials or some representation of it in every request message as part of the Authorization header, so they are prone to suffer phishing attacks if they are not correctly secured at transport level with https. In addition, most client applications typically authenticate two different things, the caller application and the user consuming the API on behalf of that application. For most cases, the schema is simplified by using a single set of username and password for authenticating both, making necessary to store those credentials temporally somewhere in memory. The true is that you can use two different identities, one for the user running the application, which you might authenticate just once during the first call when the application is initialized, and another identity for the application itself that you use on every call. Some cloud vendors like Windows Azure or Amazon Web Services have adopted an schema to authenticate the caller application based on a Message Authentication Code (MAC) generated with a symmetric algorithm using a key known by the two parties, the caller and the Web API. The caller must include a MAC as part of the Authorization header created from different pieces of information in the request message such as the address, the host, and some other headers. The Web API can authenticate the caller by using the key associated to it and validating the attached MAC in the request message. In that way, no credentials are sent as part of the request message, so there is no way an attacker to intercept the message and get access to those credentials. Anyways, this schema also suffers from some deficiencies that can generate attacks. For example, brute force can be still used to infer the key used for generating the MAC, and impersonate the original caller. This can be mitigated by renewing keys in a relative short period of time. This schema as any other can be complemented with transport security. Eran Rammer, one of the brains behind OAuth, has recently published an specification of a protocol based on MAC for Http authentication called Hawk. The initial version of the spec is available here. A curious fact is that the specification per se does not exist, and the specification itself is the code that Eran initially wrote using node.js. In that implementation, you can associate a key to an user, so once the MAC has been verified on the Web API, the user can be inferred from that key. Also a timestamp is used to avoid replay attacks. As a pet project, I decided to port that code to .NET using ASP.NET Web API, which is available also in github under https://github.com/pcibraro/hawknet Enjoy!.

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  • VS 2010 Debugger Improvements (BreakPoints, DataTips, Import/Export)

    - by ScottGu
    This is the twenty-first in a series of blog posts I’m doing on the VS 2010 and .NET 4 release.  Today’s blog post covers a few of the nice usability improvements coming with the VS 2010 debugger.  The VS 2010 debugger has a ton of great new capabilities.  Features like Intellitrace (aka historical debugging), the new parallel/multithreaded debugging capabilities, and dump debuging support typically get a ton of (well deserved) buzz and attention when people talk about the debugging improvements with this release.  I’ll be doing blog posts in the future that demonstrate how to take advantage of them as well.  With today’s post, though, I thought I’d start off by covering a few small, but nice, debugger usability improvements that were also included with the VS 2010 release, and which I think you’ll find useful. Breakpoint Labels VS 2010 includes new support for better managing debugger breakpoints.  One particularly useful feature is called “Breakpoint Labels” – it enables much better grouping and filtering of breakpoints within a project or across a solution.  With previous releases of Visual Studio you had to manage each debugger breakpoint as a separate item. Managing each breakpoint separately can be a pain with large projects and for cases when you want to maintain “logical groups” of breakpoints that you turn on/off depending on what you are debugging.  Using the new VS 2010 “breakpoint labeling” feature you can now name these “groups” of breakpoints and manage them as a unit. Grouping Multiple Breakpoints Together using a Label Below is a screen-shot of the breakpoints window within Visual Studio 2010.  This lists all of the breakpoints defined within my solution (which in this case is the ASP.NET MVC 2 code base): The first and last breakpoint in the list above breaks into the debugger when a Controller instance is created or released by the ASP.NET MVC Framework. Using VS 2010, I can now select these two breakpoints, right-click, and then select the new “Edit labels…” menu command to give them a common label/name (making them easier to find and manage): Below is the dialog that appears when I select the “Edit labels” command.  We can use it to create a new string label for our breakpoints or select an existing one we have already defined.  In this case we’ll create a new label called “Lifetime Management” to describe what these two breakpoints cover: When we press the OK button our two selected breakpoints will be grouped under the newly created “Lifetime Management” label: Filtering/Sorting Breakpoints by Label We can use the “Search” combobox to quickly filter/sort breakpoints by label.  Below we are only showing those breakpoints with the “Lifetime Management” label: Toggling Breakpoints On/Off by Label We can also toggle sets of breakpoints on/off by label group.  We can simply filter by the label group, do a Ctrl-A to select all the breakpoints, and then enable/disable all of them with a single click: Importing/Exporting Breakpoints VS 2010 now supports importing/exporting breakpoints to XML files – which you can then pass off to another developer, attach to a bug report, or simply re-load later.  To export only a subset of breakpoints, you can filter by a particular label and then click the “Export breakpoint” button in the Breakpoints window: Above I’ve filtered my breakpoint list to only export two particular breakpoints (specific to a bug that I’m chasing down).  I can export these breakpoints to an XML file and then attach it to a bug report or email – which will enable another developer to easily setup the debugger in the correct state to investigate it on a separate machine.  Pinned DataTips Visual Studio 2010 also includes some nice new “DataTip pinning” features that enable you to better see and track variable and expression values when in the debugger.  Simply hover over a variable or expression within the debugger to expose its DataTip (which is a tooltip that displays its value)  – and then click the new “pin” button on it to make the DataTip always visible: You can “pin” any number of DataTips you want onto the screen.  In addition to pinning top-level variables, you can also drill into the sub-properties on variables and pin them as well.  Below I’ve “pinned” three variables: “category”, “Request.RawUrl” and “Request.LogonUserIdentity.Name”.  Note that these last two variable are sub-properties of the “Request” object.   Associating Comments with Pinned DataTips Hovering over a pinned DataTip exposes some additional UI within the debugger: Clicking the comment button at the bottom of this UI expands the DataTip - and allows you to optionally add a comment with it: This makes it really easy to attach and track debugging notes: Pinned DataTips are usable across both Debug Sessions and Visual Studio Sessions Pinned DataTips can be used across multiple debugger sessions.  This means that if you stop the debugger, make a code change, and then recompile and start a new debug session - any pinned DataTips will still be there, along with any comments you associate with them.  Pinned DataTips can also be used across multiple Visual Studio sessions.  This means that if you close your project, shutdown Visual Studio, and then later open the project up again – any pinned DataTips will still be there, along with any comments you associate with them. See the Value from Last Debug Session (Great Code Editor Feature) How many times have you ever stopped the debugger only to go back to your code and say: $#@! – what was the value of that variable again??? One of the nice things about pinned DataTips is that they keep track of their “last value from debug session” – and you can look these values up within the VB/C# code editor even when the debugger is no longer running.  DataTips are by default hidden when you are in the code editor and the debugger isn’t running.  On the left-hand margin of the code editor, though, you’ll find a push-pin for each pinned DataTip that you’ve previously setup: Hovering your mouse over a pinned DataTip will cause it to display on the screen.  Below you can see what happens when I hover over the first pin in the editor - it displays our debug session’s last values for the “Request” object DataTip along with the comment we associated with them: This makes it much easier to keep track of state and conditions as you toggle between code editing mode and debugging mode on your projects. Importing/Exporting Pinned DataTips As I mentioned earlier in this post, pinned DataTips are by default saved across Visual Studio sessions (you don’t need to do anything to enable this). VS 2010 also now supports importing/exporting pinned DataTips to XML files – which you can then pass off to other developers, attach to a bug report, or simply re-load later. Combined with the new support for importing/exporting breakpoints, this makes it much easier for multiple developers to share debugger configurations and collaborate across debug sessions. Summary Visual Studio 2010 includes a bunch of great new debugger features – both big and small.  Today’s post shared some of the nice debugger usability improvements. All of the features above are supported with the Visual Studio 2010 Professional edition (the Pinned DataTip features are also supported in the free Visual Studio 2010 Express Editions)  I’ll be covering some of the “big big” new debugging features like Intellitrace, parallel/multithreaded debugging, and dump file analysis in future blog posts.  Hope this helps, Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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  • Access .accdb format’s

    - by wisecarver
    Were you aware there are two versions of the Access .accdb file format? The 2007 “ACE” version and the 2010 “ACE” version both use different drivers. If you’ve tried to use the Access Database .accdb format on DiscountASP.NET servers and it failed you must have been using a Data file created with the 2010 version of Access. OK, you’re shouting at me right now for even suggesting Access Databases for Shared hosting, right? I agree, SQL Server is the way to go and I personally help a lot of developers...(read more)

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  • Visual Studio 2012 RC and Windows 8 Release Review is available for download

    - by Fredrik N
    Today Visual Studio 2012 RC is available for download at:http://www.microsoft.com/visualstudio/11/en-us/downloads#express-win8EF 5, MVC 4, WebApi and much more in the RC release. Widows 8 Release Review!http://blogs.msdn.com/b/b8/archive/2012/05/31/delivering-the-windows-8-release-preview.aspxASP.NET MVC 4 RC for Visual Studio 2010 SP1http://www.microsoft.com/en-us/download/details.aspx?id=29935 Happy coding!!

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  • EF 4 Pluralization Update

    - by Ken Cox [MVP]
    I previously wrote about playing with EF 4’s PluralizationService class . Now that OrcsWeb is running ASP.NET 4, you can play with my little pluralization page and its WCF service online. The source code (such as it is!) can be downloaded from the MSDN Code Gallery here: http://code.msdn.microsoft.com/PluralizationService BTW, one annoyance is that the WDSL still includes the default namespace:  namespace="http://tempuri.org/" I swatted a couple of these instances, but if you know...(read more)

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  • Transposition - the success story of VB6 migration

    - by Visual WebGui
    Since all of you VB developers in the present or past would probably find it hard to believe that the old VB code can be migrated and modernized into the latest .NET based HTML5 without having to rewrite the application I am feeling I need to write another post on our migration solution. Hopefully, after reading this and the previous post you will be able to understand the different approach of our solution which already helps organizations around the world move away from the constraints of VB6 and...(read more)

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  • Interesting links week #10

    - by erwin21
    Below a list of interesting links that I found this week: Interaction: The Ultimate 20 Usability Tips for Your Website Frontend: Adobe Releases Flash-to-HTML5 Converter, Codenamed Wallaby Development: 10 Tips for Decreasing Web Page Load Times Ten Things Every WordPress Plugin Developer Should Know Progressive enhancement tutorial with ASP.NET MVC 3 and jQuery Marketing: 5 Tips for SEO & User-Friendly Copy Other: Interested in more interesting links follow me at twitter http://twitter.com/erwingriekspoor

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