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• Windows Azure AppFabric: ServiceBus Queue WPF Sample

  - by xamlnotes

  The latest version of the AppFabric ServiceBus now has support for queues and topics. Today I will show you a bit about using queues and also talk about some of the best practices in using them. If you are just getting started, you can check out this site for more info on Windows Azure. One of the 1st things I thought if when Azure was announced back when was how we handle fault tolerance. Web sites hosted in Azure are no much of an issue unless they are using SQL Azure and then you must account for potential fault or latency issues. Today I want to talk a bit about ServiceBus and how to handle fault tolerance.  And theres stuff like connecting to the servicebus and so on you have to take care of. To demonstrate some of the things you can do, let me walk through this sample WPF app that I am posting for you to download. To start off, the application is going to need things like the servicenamespace, issuer details and so forth to make everything work.  To facilitate this I created settings in the wpf app for all of these items. Then I mapped a static class to them and set the values when the program loads like so: StaticElements.ServiceNamespace = Convert.ToString(Properties.Settings.Default["ServiceNamespace"]); StaticElements.IssuerName = Convert.ToString(Properties.Settings.Default["IssuerName"]); StaticElements.IssuerKey = Convert.ToString(Properties.Settings.Default["IssuerKey"]); StaticElements.QueueName = Convert.ToString(Properties.Settings.Default["QueueName"]);   Now I can get to each of these elements plus some other common values or instances directly from the StaticElements class. Now, lets look at the application.  The application looks like this when it starts:   The blue graphic represents the queue we are going to use.  The next figure shows the form after items were added and the queue stats were updated . You can see how the queue has grown: To add an item to the queue, click the Add Order button which displays the following dialog: After you fill in the form and press OK, the order is published to the ServiceBus queue and the form closes. The application also allows you to read the queued items by clicking the Process Orders button. As you can see below, the form shows the queued items in a list and the  queue has disappeared as its now empty. In real practice we normally would use a Windows Service or some other automated process to subscribe to the queue and pull items from it. I created a class named ServiceBusQueueHelper that has the core queue features we need. There are three public methods: * GetOrCreateQueue – Gets an instance of the queue description if the queue exists. if not, it creates the queue and returns a description instance. * SendMessageToQueue = This method takes an order instance and sends it to the queue. The call to the queue is wrapped in the ExecuteAction method from the Transient Fault Tolerance Framework and handles all the retry logic for the queue send process. * GetOrderFromQueue – Grabs an order from the queue and returns a typed order from the queue. It also marks the message complete so the queue can remove it.   Now lets turn to the WPF window code (MainWindow.xaml.cs). The constructor contains the 4 lines shown about to setup the static variables and to perform other initialization tasks. The next few lines setup certain features we need for the ServiceBus: TokenProvider credentials = TokenProvider.CreateSharedSecretTokenProvider(StaticElements.IssuerName, StaticElements.IssuerKey); Uri serviceUri = ServiceBusEnvironment.CreateServiceUri("sb", StaticElements.ServiceNamespace, string.Empty); StaticElements.CurrentNamespaceManager = new NamespaceManager(serviceUri, credentials); StaticElements.CurrentMessagingFactory = MessagingFactory.Create(serviceUri, credentials); The next two lines update the queue name label and also set the timer to 20 seconds.             QueueNameLabel.Content = StaticElements.QueueName;             _timer.Interval = TimeSpan.FromSeconds(20);             Next I call the UpdateQueueStats to initialize the UI for the queue:             UpdateQueueStats();             _timer.Tick += new EventHandler(delegate(object s, EventArgs a)                         {                      UpdateQueueStats();                  });             _timer.Start();         } The UpdateQueueStats method shown below. You can see that it uses the GetOrCreateQueue method mentioned earlier to grab the queue description, then it can get the MessageCount property.         private void UpdateQueueStats()         {             _queueDescription = _serviceBusQueueHelper.GetOrCreateQueue();             QueueCountLabel.Content = "(" + _queueDescription.MessageCount + ")";             long count = _queueDescription.MessageCount;             long queueWidth = count * 20;             QueueRectangle.Width = queueWidth;             QueueTickCount += 1;             TickCountlabel.Content = QueueTickCount.ToString();         }   The ReadQueueItemsButton_Click event handler calls the GetOrderFromQueue method and adds the order to the listbox. If you look at the SendQueueMessageController, you can see the SendMessage method that sends an order to the queue. Its pretty simple as it just creates a new CustomerOrderEntity instance,fills it and then passes it to the SendMessageToQueue. As you can see, all of our interaction with the queue is done through the helper class (ServiceBusQueueHelper). Now lets dig into the helper class. First, before you create anything like this, download the Transient Fault Handling Framework. Microsoft provides this free and they also provide the C# source. Theres a great article that shows how to use this framework with ServiceBus. I included the entire ServiceBusQueueHelper class in List 1. Notice the using statements for TransientFaultHandling: using Microsoft.AzureCAT.Samples.TransientFaultHandling; using Microsoft.AzureCAT.Samples.TransientFaultHandling.ServiceBus; The SendMessageToQueue in Listing 1 shows how to use the async send features of ServiceBus with them wrapped in the Transient Fault Handling Framework.  It is not much different than plain old ServiceBus calls but it sure makes it easy to have the fault tolerance added almost for free. The GetOrderFromQueue uses the standard synchronous methods to access the queue. The best practices article walks through using the async approach for a receive operation also.  Notice that this method makes a call to Receive to get the message then makes a call to GetBody to get a new strongly typed instance of CustomerOrderEntity to return. Listing 1 using System; using System.Collections.Generic; using System.Linq; using System.Text; using Microsoft.AzureCAT.Samples.TransientFaultHandling; using Microsoft.AzureCAT.Samples.TransientFaultHandling.ServiceBus; using Microsoft.ServiceBus; using Microsoft.ServiceBus.Messaging; using System.Xml.Serialization; using System.Diagnostics; namespace WPFServicebusPublishSubscribeSample {     class ServiceBusQueueHelper     {         RetryPolicy currentPolicy = new RetryPolicy<ServiceBusTransientErrorDetectionStrategy>(RetryPolicy.DefaultClientRetryCount);         QueueClient currentQueueClient;         public QueueDescription GetOrCreateQueue()         {                        QueueDescription queue = null;             bool createNew = false;             try             {                 // First, let's see if a queue with the specified name already exists.                 queue = currentPolicy.ExecuteAction<QueueDescription>(() => { return StaticElements.CurrentNamespaceManager.GetQueue(StaticElements.QueueName); });                 createNew = (queue == null);             }             catch (MessagingEntityNotFoundException)             {                 // Looks like the queue does not exist. We should create a new one.                 createNew = true;             }             // If a queue with the specified name doesn't exist, it will be auto-created.             if (createNew)             {                 try                 {                     var newqueue = new QueueDescription(StaticElements.QueueName);                     queue = currentPolicy.ExecuteAction<QueueDescription>(() => { return StaticElements.CurrentNamespaceManager.CreateQueue(newqueue); });                 }                 catch (MessagingEntityAlreadyExistsException)                 {                     // A queue under the same name was already created by someone else,                     // perhaps by another instance. Let's just use it.                     queue = currentPolicy.ExecuteAction<QueueDescription>(() => { return StaticElements.CurrentNamespaceManager.GetQueue(StaticElements.QueueName); });                 }             }             currentQueueClient = StaticElements.CurrentMessagingFactory.CreateQueueClient(StaticElements.QueueName);             return queue;         }         public void SendMessageToQueue(CustomerOrderEntity Order)         {             BrokeredMessage msg = null;             GetOrCreateQueue();             // Use a retry policy to execute the Send action in an asynchronous and reliable fashion.             currentPolicy.ExecuteAction             (                 (cb) =>                 {                     // A new BrokeredMessage instance must be created each time we send it. Reusing the original BrokeredMessage instance may not                     // work as the state of its BodyStream cannot be guaranteed to be readable from the beginning.                     msg = new BrokeredMessage(Order);                     // Send the event asynchronously.                     currentQueueClient.BeginSend(msg, cb, null);                 },                 (ar) =>                 {                     try                     {                         // Complete the asynchronous operation.                         // This may throw an exception that will be handled internally by the retry policy.                         currentQueueClient.EndSend(ar);                     }                     finally                     {                         // Ensure that any resources allocated by a BrokeredMessage instance are released.                         if (msg != null)                         {                             msg.Dispose();                             msg = null;                         }                     }                 },                 (ex) =>                 {                     // Always dispose the BrokeredMessage instance even if the send                     // operation has completed unsuccessfully.                     if (msg != null)                     {                         msg.Dispose();                         msg = null;                     }                     // Always log exceptions.                     Trace.TraceError(ex.Message);                 }             );         }                 public CustomerOrderEntity GetOrderFromQueue()         {             CustomerOrderEntity Order = new CustomerOrderEntity();             QueueClient myQueueClient = StaticElements.CurrentMessagingFactory.CreateQueueClient(StaticElements.QueueName, ReceiveMode.PeekLock);             BrokeredMessage message;             ServiceBusQueueHelper serviceBusQueueHelper = new ServiceBusQueueHelper();             QueueDescription queueDescription;             queueDescription = serviceBusQueueHelper.GetOrCreateQueue();             if (queueDescription.MessageCount > 0)             {                 message = myQueueClient.Receive(TimeSpan.FromSeconds(90));                 if (message != null)                 {                     try                     {                         Order = message.GetBody<CustomerOrderEntity>();                         message.Complete();                     }                     catch (Exception ex)                     {                         throw ex;                     }                 }                 else                 {                     throw new Exception("Did not receive the messages");                 }             }             return Order;         }     } } I will post a link to the download demo in a separate post soon.

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• Demystifying Silverlight Dependency Properties

  - by dwahlin

  I have the opportunity to teach a lot of people about Silverlight (amongst other technologies) and one of the topics that definitely confuses people initially is the concept of dependency properties. I confess that when I first heard about them my initial thought was “Why do we need a specialized type of property?” While you can certainly use standard CLR properties in Silverlight applications, Silverlight relies heavily on dependency properties for just about everything it does behind the scenes. In fact, dependency properties are an essential part of the data binding, template, style and animation functionality available in Silverlight. They simply back standard CLR properties. In this post I wanted to put together a (hopefully) simple explanation of dependency properties and why you should care about them if you’re currently working with Silverlight or looking to move to it.   What are Dependency Properties? XAML provides a great way to define layout controls, user input controls, shapes, colors and data binding expressions in a declarative manner. There’s a lot that goes on behind the scenes in order to make XAML work and an important part of that magic is the use of dependency properties. If you want to bind data to a property, style it, animate it or transform it in XAML then the property involved has to be a dependency property to work properly. If you’ve ever positioned a control in a Canvas using Canvas.Left or placed a control in a specific Grid row using Grid.Row then you’ve used an attached property which is a specialized type of dependency property. Dependency properties play a key role in XAML and the overall Silverlight framework. Any property that you bind, style, template, animate or transform must be a dependency property in Silverlight applications. You can programmatically bind values to controls and work with standard CLR properties, but if you want to use the built-in binding expressions available in XAML (one of my favorite features) or the Binding class available through code then dependency properties are a necessity. Dependency properties aren’t needed in every situation, but if you want to customize your application very much you’ll eventually end up needing them. For example, if you create a custom user control and want to expose a property that consumers can use to change the background color, you have to define it as a dependency property if you want bindings, styles and other features to be available for use. Now that the overall purpose of dependency properties has been discussed let’s take a look at how you can create them. Creating Dependency Properties When .NET first came out you had to write backing fields for each property that you defined as shown next: Brush _ScheduleBackground; public Brush ScheduleBackground { get { return _ScheduleBackground; } set { _ScheduleBackground = value; } } Although .NET 2.0 added auto-implemented properties (for example: public Brush ScheduleBackground { get; set; }) where the compiler would automatically generate the backing field used by get and set blocks, the concept is still the same as shown in the above code; a property acts as a wrapper around a field. Silverlight dependency properties replace the _ScheduleBackground field shown in the previous code and act as the backing store for a standard CLR property. The following code shows an example of defining a dependency property named ScheduleBackgroundProperty: public static readonly DependencyProperty ScheduleBackgroundProperty = DependencyProperty.Register("ScheduleBackground", typeof(Brush), typeof(Scheduler), null);   Looking through the code the first thing that may stand out is that the definition for ScheduleBackgroundProperty is marked as static and readonly and that the property appears to be of type DependencyProperty. This is a standard pattern that you’ll use when working with dependency properties. You’ll also notice that the property explicitly adds the word “Property” to the name which is another standard you’ll see followed. In addition to defining the property, the code also makes a call to the static DependencyProperty.Register method and passes the name of the property to register (ScheduleBackground in this case) as a string. The type of the property, the type of the class that owns the property and a null value (more on the null value later) are also passed. In this example a class named Scheduler acts as the owner. The code handles registering the property as a dependency property with the call to Register(), but there’s a little more work that has to be done to allow a value to be assigned to and retrieved from the dependency property. The following code shows the complete code that you’ll typically use when creating a dependency property. You can find code snippets that greatly simplify the process of creating dependency properties out on the web. The MVVM Light download available from http://mvvmlight.codeplex.com comes with built-in dependency properties snippets as well. public static readonly DependencyProperty ScheduleBackgroundProperty = DependencyProperty.Register("ScheduleBackground", typeof(Brush), typeof(Scheduler), null); public Brush ScheduleBackground { get { return (Brush)GetValue(ScheduleBackgroundProperty); } set { SetValue(ScheduleBackgroundProperty, value); } } The standard CLR property code shown above should look familiar since it simply wraps the dependency property. However, you’ll notice that the get and set blocks call GetValue and SetValue methods respectively to perform the appropriate operation on the dependency property. GetValue and SetValue are members of the DependencyObject class which is another key component of the Silverlight framework. Silverlight controls and classes (TextBox, UserControl, CompositeTransform, DataGrid, etc.) ultimately derive from DependencyObject in their inheritance hierarchy so that they can support dependency properties. Dependency properties defined in Silverlight controls and other classes tend to follow the pattern of registering the property by calling Register() and then wrapping the dependency property in a standard CLR property (as shown above). They have a standard property that wraps a registered dependency property and allows a value to be assigned and retrieved. If you need to expose a new property on a custom control that supports data binding expressions in XAML then you’ll follow this same pattern. Dependency properties are extremely useful once you understand why they’re needed and how they’re defined. Detecting Changes and Setting Defaults When working with dependency properties there will be times when you want to assign a default value or detect when a property changes so that you can keep the user interface in-sync with the property value. Silverlight’s DependencyProperty.Register() method provides a fourth parameter that accepts a PropertyMetadata object instance. PropertyMetadata can be used to hook a callback method to a dependency property. The callback method is called when the property value changes. PropertyMetadata can also be used to assign a default value to the dependency property. By assigning a value of null for the final parameter passed to Register() you’re telling the property that you don’t care about any changes and don’t have a default value to apply. Here are the different constructor overloads available on the PropertyMetadata class: PropertyMetadata Constructor Overload Description PropertyMetadata(Object) Used to assign a default value to a dependency property. PropertyMetadata(PropertyChangedCallback) Used to assign a property changed callback method. PropertyMetadata(Object, PropertyChangedCalback) Used to assign a default property value and a property changed callback.   There are many situations where you need to know when a dependency property changes or where you want to apply a default. Performing either task is easily accomplished by creating a new instance of the PropertyMetadata class and passing the appropriate values to its constructor. The following code shows an enhanced version of the initial dependency property code shown earlier that demonstrates these concepts: public Brush ScheduleBackground { get { return (Brush)GetValue(ScheduleBackgroundProperty); } set { SetValue(ScheduleBackgroundProperty, value); } } public static readonly DependencyProperty ScheduleBackgroundProperty = DependencyProperty.Register("ScheduleBackground", typeof(Brush), typeof(Scheduler), new PropertyMetadata(new SolidColorBrush(Colors.LightGray), ScheduleBackgroundChanged)); private static void ScheduleBackgroundChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { var scheduler = d as Scheduler; scheduler.Background = e.NewValue as Brush; } The code wires ScheduleBackgroundProperty to a property change callback method named ScheduleBackgroundChanged. What’s interesting is that this callback method is static (as is the dependency property) so it gets passed the instance of the object that owns the property that has changed (otherwise we wouldn’t be able to get to the object instance). In this example the dependency object is cast to a Scheduler object and its Background property is assigned to the new value of the dependency property. The code also handles assigning a default value of LightGray to the dependency property by creating a new instance of a SolidColorBrush. To Sum Up In this post you’ve seen the role of dependency properties and how they can be defined in code. They play a big role in XAML and the overall Silverlight framework. You can think of dependency properties as being replacements for fields that you’d normally use with standard CLR properties. In addition to a discussion on how dependency properties are created, you also saw how to use the PropertyMetadata class to define default dependency property values and hook a dependency property to a callback method. The most important thing to understand with dependency properties (especially if you’re new to Silverlight) is that they’re needed if you want a property to support data binding, animations, transformations and styles properly. Any time you create a property on a custom control or user control that has these types of requirements you’ll want to pick a dependency property over of a standard CLR property with a backing field. There’s more that can be covered with dependency properties including a related property called an attached property….more to come.

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• Routing to a Controller with no View in Angular

  - by Rick Strahl

  I've finally had some time to put Angular to use this week in a small project I'm working on for fun. Angular's routing is great and makes it real easy to map URL routes to controllers and model data into views. But what if you don't actually need a view, if you effectively need a headless controller that just runs code, but doesn't render a view?Preserve the ViewWhen Angular navigates a route and and presents a new view, it loads the controller and then renders the view from scratch. Views are not cached or stored, but displayed and then removed. So if you have routes configured like this:'use strict'; // Declare app level module which depends on filters, and services window.myApp = angular.module('myApp', ['myApp.filters', 'myApp.services', 'myApp.directives', 'myApp.controllers']). config(['$routeProvider', function($routeProvider) { $routeProvider.when('/map', { template: "partials/map.html ", controller: 'mapController', reloadOnSearch: false, animation: 'slide' }); … $routeProvider.otherwise({redirectTo: '/map'}); }]); Angular routes to the mapController and then re-renders the map.html template with the new data from the $scope filled in.But, but… I don't want a new View!Now in most cases this works just fine. If I'm rendering plain DOM content, or textboxes in a form interface that is all fine and dandy - it's perfectly fine to completely re-render the UI.But in some cases, the UI that's being managed has state and shouldn't be redrawn. In this case the main page in question has a Google Map on it. The map is  going to be manipulated throughout the lifetime of the application and the rest of the pages. In my application I have a toolbar on the bottom and the rest of the content is replaced/switched out by the Angular Views:The problem is that the map shouldn't be redrawn each time the Location view is activated. It should maintain its state, such as the current position selected (which can move), and shouldn't redraw due to the overhead of re-rendering the initial map.Originally I set up the map, exactly like all my other views - as a partial, that is rendered with a separate file, but that didn't work.The Workaround - Controller Only RoutesThe workaround for this goes decidedly against Angular's way of doing things:Setting up a Template-less RouteIn-lining the map view directly into the main pageHiding and showing the map view manuallyLet's see how this works.Controller Only RouteThe template-less route is basically a route that doesn't have any template to render. This is not directly supported by Angular, but thankfully easy to fake. The end goal here is that I want to simply have the Controller fire and then have the controller manage the display of the already active view by hiding and showing the map and any other view content, in effect bypassing Angular's view display management.In short - I want a controller action, but no view rendering.The controller-only or template-less route looks like this: $routeProvider.when('/map', { template: " ", // just fire controller controller: 'mapController', animation: 'slide' });Notice I'm using the template property rather than templateUrl (used in the first example above), which allows specifying a string template, and leaving it blank. The template property basically allows you to provide a templated string using Angular's HandleBar like binding syntax which can be useful at times. You can use plain strings or strings with template code in the template, or as I'm doing here a blank string to essentially fake 'just clear the view'. In-lined ViewSo if there's no view where does the HTML go? Because I don't want Angular to manage the view the map markup is in-lined directly into the page. So instead of rendering the map into the Angular view container, the content is simply set up as inline HTML to display as a sibling to the view container.<div id="MapContent" data-icon="LocationIcon" ng-controller="mapController" style="display:none"> <div class="headerbar"> <div class="right-header" style="float:right"> <a id="btnShowSaveLocationDialog" class="iconbutton btn btn-sm" href="#/saveLocation" style="margin-right: 2px;"> <i class="icon-ok icon-2x" style="color: lightgreen; "></i> Save Location </a> </div> <div class="left-header">GeoCrumbs</div> </div> <div class="clearfix"></div> <div id="Message"> <i id="MessageIcon"></i> <span id="MessageText"></span> </div> <div id="Map" class="content-area"> </div> </div> <div id="ViewPlaceholder" ng-view></div>Note that there's the #MapContent element and the #ViewPlaceHolder. The #MapContent is my static map view that is always 'live' and is initially hidden. It is initially hidden and doesn't get made visible until the MapController controller activates it which does the initial rendering of the map. After that the element is persisted with the map data already loaded and any future access only updates the map with new locations/pins etc.Note that default route is assigned to the mapController, which means that the mapController is fired right as the page loads, which is actually a good thing in this case, as the map is the cornerstone of this app that is manipulated by some of the other controllers/views.The Controller handles some UISince there's effectively no view activation with the template-less route, the controller unfortunately has to take over some UI interaction directly. Specifically it has to swap the hidden state between the map and any of the other views.Here's what the controller looks like:myApp.controller('mapController', ["$scope", "$routeParams", "locationData", function($scope, $routeParams, locationData) { $scope.locationData = locationData.location; $scope.locationHistory = locationData.locationHistory; if ($routeParams.mode == "currentLocation") { bc.getCurrentLocation(false); } bc.showMap(false,"#LocationIcon"); }]);bc.showMap is responsible for a couple of display tasks that hide/show the views/map and for activating/deactivating icons. The code looks like this:this.showMap = function (hide,selActiveIcon) { if (!hide) $("#MapContent").show(); else { $("#MapContent").hide(); } self.fitContent(); if (selActiveIcon) { $(".iconbutton").removeClass("active"); $(selActiveIcon).addClass("active"); } };Each of the other controllers in the app also call this function when they are activated to basically hide the map and make the View Content area visible. The map controller makes the map.This is UI code and calling this sort of thing from controllers is generally not recommended, but I couldn't figure out a way using directives to make this work any more easily than this. It'd be easy to hide and show the map and view container using a flag an ng-show, but it gets tricky because of scoping of the $scope. I would have to resort to storing this setting on the $rootscope which I try to avoid. The same issues exists with the icons.It sure would be nice if Angular had a way to explicitly specify that a View shouldn't be destroyed when another view is activated, so currently this workaround is required. Searching around, I saw a number of whacky hacks to get around this, but this solution I'm using here seems much easier than any of that I could dig up even if it doesn't quite fit the 'Angular way'.Angular nice, until it's notOverall I really like Angular and the way it works although it took me a bit of time to get my head around how all the pieces fit together. Once I got the idea how the app/routes, the controllers and views snap together, putting together Angular pages becomes fairly straightforward. You can get quite a bit done never going beyond those basics. For most common things Angular's default routing and view presentation works very well.But, when you do something a bit more complex, where there are multiple dependencies or as in this case where Angular doesn't appear to support a feature that's absolutely necessary, you're on your own. Finding information on more advanced topics is not trivial especially since versions are changing so rapidly and the low level behaviors are changing frequently so finding something that works is often an exercise in trial and error. Not that this is surprising. Angular is a complex piece of kit as are all the frameworks that try to hack JavaScript into submission to do something that it was really never designed to. After all everything about a framework like Angular is an elaborate hack. A lot of shit has to happen to make this all work together and at that Angular (and Ember, Durandel etc.) are pretty amazing pieces of JavaScript code. So no harm, no foul, but I just can't help feeling like working in toy sandbox at times :-)© Rick Strahl, West Wind Technologies, 2005-2013Posted in Angular  JavaScript   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• How to Avoid Your Next 12-Month Science Project

  - by constant

  While most customers immediately understand how the magic of Oracle's Hybrid Columnar Compression, intelligent storage servers and flash memory make Exadata uniquely powerful against home-grown database systems, some people think that Exalogic is nothing more than a bunch of x86 servers, a storage appliance and an InfiniBand (IB) network, built into a single rack. After all, isn't this exactly what the High Performance Computing (HPC) world has been doing for decades? On the surface, this may be true. And some people tried exactly that: They tried to put together their own version of Exalogic, but then they discover there's a lot more to building a system than buying hardware and assembling it together. IT is not Ikea. Why is that so? Could it be there's more going on behind the scenes than merely putting together a bunch of servers, a storage array and an InfiniBand network into a rack? Let's explore some of the special sauce that makes Exalogic unique and un-copyable, so you can save yourself from your next 6- to 12-month science project that distracts you from doing real work that adds value to your company. Engineering Systems is Hard Work! The backbone of Exalogic is its InfiniBand network: 4 times better bandwidth than even 10 Gigabit Ethernet, and only about a tenth of its latency. What a potential for increased scalability and throughput across the middleware and database layers! But InfiniBand is a beast that needs to be tamed: It is true that Exalogic uses a standard, open-source Open Fabrics Enterprise Distribution (OFED) InfiniBand driver stack. Unfortunately, this software has been developed by the HPC community with fastest speed in mind (which is good) but, despite the name, not many other enterprise-class requirements are included (which is less good). Here are some of the improvements that Oracle's InfiniBand development team had to add to the OFED stack to make it enterprise-ready, simply because typical HPC users didn't have the need to implement them: More than 100 bug fixes in the pieces that were not related to the Message Passing Interface Protocol (MPI), which is the protocol that HPC users use most of the time, but which is less useful in the enterprise. Performance optimizations and tuning across the whole IB stack: From Switches, Host Channel Adapters (HCAs) and drivers to low-level protocols, middleware and applications. Yes, even the standard HPC IB stack could be improved in terms of performance. Ethernet over IB (EoIB): Exalogic uses InfiniBand internally to reach high performance, but it needs to play nicely with datacenters around it. That's why Oracle added Ethernet over InfiniBand technology to it that allows for creating many virtual 10GBE adapters inside Exalogic's nodes that are aggregated and connected to Exalogic's IB gateway switches. While this is an open standard, it's up to the vendor to implement it. In this case, Oracle integrated the EoIB stack with Oracle's own IB to 10GBE gateway switches, and made it fully virtualized from the beginning. This means that Exalogic customers can completely rewire their server infrastructure inside the rack without having to physically pull or plug a single cable - a must-have for every cloud deployment. Anybody who wants to match this level of integration would need to add an InfiniBand switch development team to their project. Or just buy Oracle's gateway switches, which are conveniently shipped with a whole server infrastructure attached! IPv6 support for InfiniBand's Sockets Direct Protocol (SDP), Reliable Datagram Sockets (RDS), TCP/IP over IB (IPoIB) and EoIB protocols. Because no IPv6 = not very enterprise-class. HA capability for SDP. High Availability is not a big requirement for HPC, but for enterprise-class application servers it is. Every node in Exalogic's InfiniBand network is connected twice for redundancy. If any cable or port or HCA fails, there's always a replacement link ready to take over. This requires extra magic at the protocol level to work. So in addition to Weblogic's failover capabilities, Oracle implemented IB automatic path migration at the SDP level to avoid unnecessary failover operations at the middleware level. Security, for example spoof-protection. Another feature that is less important for traditional users of InfiniBand, but very important for enterprise customers. InfiniBand Partitioning and Quality-of-Service (QoS): One of the first questions we get from customers about Exalogic is: “How can we implement multi-tenancy?” The answer is to partition your IB network, which effectively creates many networks that work independently and that are protected at the lowest networking layer possible. In addition to that, QoS allows administrators to prioritize traffic flow in multi-tenancy environments so they can keep their service levels where it matters most. Resilient IB Fabric Management: InfiniBand is a self-managing network, so a lot of the magic lies in coming up with the right topology and in teaching the subnet manager how to properly discover and manage the network. Oracle's Infiniband switches come with pre-integrated, highly available fabric management with seamless integration into Oracle Enterprise Manager Ops Center. In short: Oracle elevated the OFED InfiniBand stack into an enterprise-class networking infrastructure. Many years and multiple teams of manpower went into the above improvements - this is something you can only get from Oracle, because no other InfiniBand vendor can give you these features across the whole stack! Exabus: Because it's not About the Size of Your Network, it's How You Use it! So let's assume that you somehow were able to get your hands on an enterprise-class IB driver stack. Or maybe you don't care and are just happy with the standard OFED one? Anyway, the next step is to actually leverage that InfiniBand performance. Here are the choices: Use traditional TCP/IP on top of the InfiniBand stack, Develop your own integration between your middleware and the lower-level (but faster) InfiniBand protocols. While more bandwidth is always a good thing, it's actually the low latency that enables superior performance for your applications when running on any networking infrastructure: The lower the latency, the faster the response travels through the network and the more transactions you can close per second. The reason why InfiniBand is such a low latency technology is that it gets rid of most if not all of your traditional networking protocol stack: Data is literally beamed from one region of RAM in one server into another region of RAM in another server with no kernel/drivers/UDP/TCP or other networking stack overhead involved! Which makes option 1 a no-go: Adding TCP/IP on top of InfiniBand is like adding training wheels to your racing bike. It may be ok in the beginning and for development, but it's not quite the performance IB was meant to deliver. Which only leaves option 2: Integrating your middleware with fast, low-level InfiniBand protocols. And this is what Exalogic's "Exabus" technology is all about. Here are a few Exabus features that help applications leverage the performance of InfiniBand in Exalogic: RDMA and SDP integration at the JDBC driver level (SDP), for Oracle Weblogic (SDP), Oracle Coherence (RDMA), Oracle Tuxedo (RDMA) and the new Oracle Traffic Director (RDMA) on Exalogic. Using these protocols, middleware can communicate a lot faster with each other and the Oracle database than by using standard networking protocols, Seamless Integration of Ethernet over InfiniBand from Exalogic's Gateway switches into the OS, Oracle Weblogic optimizations for handling massive amounts of parallel transactions. Because if you have an 8-lane Autobahn, you also need to improve your ramps so you can feed it with many cars in parallel. Integration of Weblogic with Oracle Exadata for faster performance, optimized session management and failover. As you see, “Exabus” is Oracle's word for describing all the InfiniBand enhancements Oracle put into Exalogic: OFED stack enhancements, protocols for faster IB access, and InfiniBand support and optimizations at the virtualization and middleware level. All working together to deliver the full potential of InfiniBand performance. Who else has 100% control over their middleware so they can develop their own low-level protocol integration with InfiniBand? Even if you take an open source approach, you're looking at years of development work to create, test and support a whole new networking technology in your middleware! The Extras: Less Hassle, More Productivity, Faster Time to Market And then there are the other advantages of Engineered Systems that are true for Exalogic the same as they are for every other Engineered System: One simple purchasing process: No headaches due to endless RFPs and no “Will X work with Y?” uncertainties. Everything has been engineered together: All kinds of bugs and problems have been already fixed at the design level that would have only manifested themselves after you have built the system from scratch. Everything is built, tested and integrated at the factory level . Less integration pain for you, faster time to market. Every Exalogic machine world-wide is identical to Oracle's own machines in the lab: Instant replication of any problems you may encounter, faster time to resolution. Simplified patching, management and operations. One throat to choke: Imagine finger-pointing hell for systems that have been put together using several different vendors. Oracle's Engineered Systems have a single phone number that customers can call to get their problems solved. For more business-centric values, read The Business Value of Engineered Systems. Conclusion: Buy Exalogic, or get ready for a 6-12 Month Science Project And here's the reason why it's not easy to "build your own Exalogic": There's a lot of work required to make such a system fly. In fact, anybody who is starting to "just put together a bunch of servers and an InfiniBand network" is really looking at a 6-12 month science project. And the outcome is likely to not be very enterprise-class. And it won't have Exalogic's performance either. Because building an Engineered System is literally rocket science: It takes a lot of time, effort, resources and many iterations of design/test/analyze/fix to build such a system. That's why InfiniBand has been reserved for HPC scientists for such a long time. And only Oracle can bring the power of InfiniBand in an enterprise-class, ready-to use, pre-integrated version to customers, without the develop/integrate/support pain. For more details, check the new Exalogic overview white paper which was updated only recently. P.S.: Thanks to my colleagues Ola, Paul, Don and Andy for helping me put together this article! var flattr_uid = '26528'; var flattr_tle = 'How to Avoid Your Next 12-Month Science Project'; var flattr_dsc = 'While most customers immediately understand how the magic of Oracle's Hybrid Columnar Compression, intelligent storage servers and flash memory make Exadata uniquely powerful against home-grown database systems, some people think that Exalogic is nothing more than a bunch of x86 servers, a storage appliance and an InfiniBand (IB) network, built into a single rack.After all, isn't this exactly what the High Performance Computing (HPC) world has been doing for decades?On the surface, this may be true. And some people tried exactly that: They tried to put together their own version of Exalogic, but then they discover there's a lot more to building a system than buying hardware and assembling it together. IT is not Ikea.Why is that so? Could it be there's more going on behind the scenes than merely putting together a bunch of servers, a storage array and an InfiniBand network into a rack? Let's explore some of the special sauce that makes Exalogic unique and un-copyable, so you can save yourself from your next 6- to 12-month science project that distracts you from doing real work that adds value to your company.'; var flattr_tag = 'Engineered Systems,Engineered Systems,Infiniband,Integration,latency,Oracle,performance'; var flattr_cat = 'text'; var flattr_url = 'http://constantin.glez.de/blog/2012/04/how-avoid-your-next-12-month-science-project'; var flattr_lng = 'en_GB'

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• A Simple Approach For Presenting With Code Samples

  - by Jesse Taber

  Originally posted on: http://geekswithblogs.net/GruffCode/archive/2013/07/31/a-simple-approach-for-presenting-with-code-samples.aspxI’ve been getting ready for a presentation and have been struggling a bit with the best way to show and execute code samples. I don’t present often (hardly ever), but when I do I like the presentation to have a lot of succinct and executable code snippets to help illustrate the points that I’m making. Depending on what the presentation is about, I might just want to build an entire sample application that I would run during the presentation. In other cases, however, building a full-blown application might not really be the best way to present the code. The presentation I’m working on now is for an open source utility library for dealing with dates and times. I could have probably cooked up a sample app for accepting date and time input and then contrived ways in which it could put the library through its paces, but I had trouble coming up with one app that would illustrate all of the various features of the library that I wanted to highlight. I finally decided that what I really needed was an approach that met the following criteria: Simple: I didn’t want the user interface or overall architecture of a sample application to serve as a distraction from the demonstration of the syntax of the library that the presentation is about. I want to be able to present small bits of code that are focused on accomplishing a single task. Several of these examples will look similar, and that’s OK. I want each sample to “stand on its own” and not rely much on external classes or methods (other than the library that is being presented, of course). “Debuggable” (not really a word, I know): I want to be able to easily run the sample with the debugger attached in Visual Studio should I want to step through any bits of code and show what certain values might be at run time. As far as I know this rules out something like LinqPad, though using LinqPad to present code samples like this is actually a very interesting idea that I might explore another time. Flexible and Selectable: I’m going to have lots of code samples to show, and I want to be able to just package them all up into a single project or module and have an easy way to just run the sample that I want on-demand. Since I’m presenting on a .NET framework library, one of the simplest ways in which I could execute some code samples would be to just create a Console application and use Console.WriteLine to output the pertinent info at run time. This gives me a “no frills” harness from which to run my code samples, and I just hit ‘F5’ to run it with the debugger. This satisfies numbers 1 and 2 from my list of criteria above, but item 3 is a little harder. By default, just running a console application is going to execute the ‘main’ method, and then terminate the program after all code is executed. If I want to have several different code samples and run them one at a time, it would be cumbersome to keep swapping the code I want in and out of the ‘main’ method of the console application. What I really want is an easy way to keep the console app running throughout the whole presentation and just have it run the samples I want when I want. I could setup a simple Windows Forms or WPF desktop application with buttons for the different samples, but then I’m getting away from my first criteria of keeping things as simple as possible. Infinite Loops To The Rescue I found a way to have a simple console application satisfy all three of my requirements above, and it involves using an infinite loop and some Console.ReadLine calls that will give the user an opportunity to break out and exit the program. (All programs that need to run until they are closed explicitly (or crash!) likely use similar constructs behind the scenes. Create a new Windows Forms project, look in the ‘Program.cs’ that gets generated, and then check out the docs for the Application.Run method that it calls.). Here’s how the main method might look: 1: static void Main(string[] args) 2: { 3: do 4: { 5: Console.Write("Enter command or 'exit' to quit: > "); 6: var command = Console.ReadLine(); 7: if ((command ?? string.Empty).Equals("exit", StringComparison.OrdinalIgnoreCase)) 8: { 9: Console.WriteLine("Quitting."); 10: break; 11: } 12: 13: } while (true); 14: } The idea here is the app prompts me for the command I want to run, or I can type in ‘exit’ to break out of the loop and let the application close. The only trick now is to create a set of commands that map to each of the code samples that I’m going to want to run. Each sample is already encapsulated in a single public method in a separate class, so I could just write a big switch statement or create a hashtable/dictionary that maps command text to an Action that will invoke the proper method, but why re-invent the wheel? CLAP For Your Own Presentation I’ve blogged about the CLAP library before, and it turns out that it’s a great fit for satisfying criteria #3 from my list above. CLAP lets you decorate methods in a class with an attribute and then easily invoke those methods from within a console application. CLAP was designed to take the arguments passed into the console app from the command line and parse them to determine which method to run and what arguments to pass to that method, but there’s no reason you can’t re-purpose it to accept command input from within the infinite loop defined above and invoke the corresponding method. Here’s how you might define a couple of different methods to contain two different code samples that you want to run during your presentation: 1: public static class CodeSamples 2: { 3: [Verb(Aliases="one")] 4: public static void SampleOne() 5: { 6: Console.WriteLine("This is sample 1"); 7: } 8:   9: [Verb(Aliases="two")] 10: public static void SampleTwo() 11: { 12: Console.WriteLine("This is sample 2"); 13: } 14: } A couple of things to note about the sample above: I’m using static methods. You don’t actually need to use static methods with CLAP, but the syntax ends up being a bit simpler and static methods happen to lend themselves well to the “one self-contained method per code sample” approach that I want to use. The methods are decorated with a ‘Verb’ attribute. This tells CLAP that they are eligible targets for commands. The “Aliases” argument lets me give them short and easy-to-remember aliases that can be used to invoke them. By default, CLAP just uses the full method name as the command name, but with aliases you can simply the usage a bit. I’m not using any parameters. CLAP’s main feature is its ability to parse out arguments from a command line invocation of a console application and automatically pass them in as parameters to the target methods. My code samples don’t need parameters ,and honestly having them would complicate giving the presentation, so this is a good thing. You could use this same approach to invoke methods with parameters, but you’d have a couple of things to figure out. When you invoke a .NET application from the command line, Windows will parse the arguments and pass them in as a string array (called ‘args’ in the boilerplate console project Program.cs). The parsing that gets done here is smart enough to deal with things like treating strings in double quotes as one argument, and you’d have to re-create that within your infinite loop if you wanted to use parameters. I plan on either submitting a pull request to CLAP to add this capability or maybe just making a small utility class/extension method to do it and posting that here in the future. So I now have a simple class with static methods to contain my code samples, and an infinite loop in my ‘main’ method that can accept text commands. Wiring this all up together is pretty easy: 1: static void Main(string[] args) 2: { 3: do 4: { 5: try 6: { 7: Console.Write("Enter command or 'exit' to quit: > "); 8: var command = Console.ReadLine(); 9: if ((command ?? string.Empty).Equals("exit", StringComparison.OrdinalIgnoreCase)) 10: { 11: Console.WriteLine("Quitting."); 12: break; 13: } 14:   15: Parser.Run<CodeSamples>(new[] { command }); 16: Console.WriteLine("---------------------------------------------------------"); 17: } 18: catch (Exception ex) 19: { 20: Console.Error.WriteLine("Error: " + ex.Message); 21: } 22:   23: } while (true); 24: } Note that I’m now passing the ‘CodeSamples’ class into the CLAP ‘Parser.Run’ as a type argument. This tells CLAP to inspect that class for methods that might be able to handle the commands passed in. I’m also throwing in a little “----“ style line separator and some basic error handling (because I happen to know that some of the samples are going to throw exceptions for demonstration purposes) and I’m good to go. Now during my presentation I can just have the console application running the whole time with the debugger attached and just type in the alias of the code sample method that I want to run when I want to run it.

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• UndoRedo on Nodes

  - by Geertjan

  When a change is made to the property in the Properties Window, below, the undo/redo functionality becomes enabled: When undo/redo are invoked, e.g., via the buttons in the toolbar, the display name of the node changes accordingly. The only problem I have is that the buttons only become enabled when the Person Window is selected, not when the Properties Window is selected, which would be desirable. Here's the Person object: public class Person implements PropertyChangeListener {     private String name;     public static final String PROP_NAME = "name";     public Person(String name) {         this.name = name;     }     public String getName() {         return name;     }     public void setName(String name) {         String oldName = this.name;         this.name = name;         propertyChangeSupport.firePropertyChange(PROP_NAME, oldName, name);     }     private transient final PropertyChangeSupport propertyChangeSupport = new PropertyChangeSupport(this);     public void addPropertyChangeListener(PropertyChangeListener listener) {         propertyChangeSupport.addPropertyChangeListener(listener);     }     public void removePropertyChangeListener(PropertyChangeListener listener) {         propertyChangeSupport.removePropertyChangeListener(listener);     }     @Override     public void propertyChange(PropertyChangeEvent evt) {         propertyChangeSupport.firePropertyChange(evt);     } } And here's the Node with UndoRedo enablement: public class PersonNode extends AbstractNode implements UndoRedo.Provider, PropertyChangeListener {     private UndoRedo.Manager manager = new UndoRedo.Manager();     private boolean undoRedoEvent;     public PersonNode(Person person) {         super(Children.LEAF, Lookups.singleton(person));         person.addPropertyChangeListener(this);         setDisplayName(person.getName());     }     @Override     protected Sheet createSheet() {         Sheet sheet = Sheet.createDefault();         Sheet.Set set = Sheet.createPropertiesSet();         set.put(new NameProperty(getLookup().lookup(Person.class)));         sheet.put(set);         return sheet;     }     @Override     public void propertyChange(PropertyChangeEvent evt) {         if (evt.getPropertyName().equals(Person.PROP_NAME)) {             firePropertyChange(evt.getPropertyName(), evt.getOldValue(), evt.getNewValue());         }     }     public void fireUndoableEvent(String property, Person source, Object oldValue, Object newValue) {         manager.addEdit(new MyAbstractUndoableEdit(source, oldValue, newValue));     }     @Override     public UndoRedo getUndoRedo() {         return manager;     }     @Override     public String getDisplayName() {         Person p = getLookup().lookup(Person.class);         if (p != null) {             return p.getName();         }         return super.getDisplayName();     }     private class NameProperty extends PropertySupport.ReadWrite<String> {         private Person p;         public NameProperty(Person p) {             super("name", String.class, "Name", "Name of Person");             this.p = p;         }         @Override         public String getValue() throws IllegalAccessException, InvocationTargetException {             return p.getName();         }         @Override         public void setValue(String newValue) throws IllegalAccessException, IllegalArgumentException, InvocationTargetException {             String oldValue = p.getName();             p.setName(newValue);             if (!undoRedoEvent) {                 fireUndoableEvent("name", p, oldValue, newValue);                 fireDisplayNameChange(oldValue, newValue);             }         }     }     class MyAbstractUndoableEdit extends AbstractUndoableEdit {         private final String oldValue;         private final String newValue;         private final Person source;         private MyAbstractUndoableEdit(Person source, Object oldValue, Object newValue) {             this.oldValue = oldValue.toString();             this.newValue = newValue.toString();             this.source = source;         }         @Override         public boolean canRedo() {             return true;         }         @Override         public boolean canUndo() {             return true;         }         @Override         public void undo() throws CannotUndoException {             undoRedoEvent = true;             source.setName(oldValue.toString());             fireDisplayNameChange(oldValue, newValue);             undoRedoEvent = false;         }         @Override         public void redo() throws CannotUndoException {             undoRedoEvent = true;             source.setName(newValue.toString());             fireDisplayNameChange(oldValue, newValue);             undoRedoEvent = false;         }     } } Does anyone out there know how to have the Undo/Redo functionality enabled when the Properties Window is selected?

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• Custom Gesture in cocos2d

  - by Lewis

  I've found a little tutorial that would be useful for my game: http://blog.mellenthin.de/archives/2012/02/13/an-one-finger-rotation-gesture-recognizer/ But I can't work out how to convert that gesture to work with cocos2d, I have found examples of pre made gestures in cocos2d, but no custom ones, is it possible? EDIT STILL HAVING PROBLEMS WITH THIS: I've added the code from Sentinel below (from SO), the Gesture and RotateGesture have both been added to my solution and are compiling. Although In the rotation class now I only see selectors, how do I set those up? As the custom gesture found in that project above looks like: header file for custom gesture: #import <Foundation/Foundation.h> #import <UIKit/UIGestureRecognizerSubclass.h> @protocol OneFingerRotationGestureRecognizerDelegate <NSObject> @optional - (void) rotation: (CGFloat) angle; - (void) finalAngle: (CGFloat) angle; @end @interface OneFingerRotationGestureRecognizer : UIGestureRecognizer { CGPoint midPoint; CGFloat innerRadius; CGFloat outerRadius; CGFloat cumulatedAngle; id <OneFingerRotationGestureRecognizerDelegate> target; } - (id) initWithMidPoint: (CGPoint) midPoint innerRadius: (CGFloat) innerRadius outerRadius: (CGFloat) outerRadius target: (id) target; - (void)reset; - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event; - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event; - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event; - (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event; @end .m for custom gesture file: #include <math.h> #import "OneFingerRotationGestureRecognizer.h" @implementation OneFingerRotationGestureRecognizer // private helper functions CGFloat distanceBetweenPoints(CGPoint point1, CGPoint point2); CGFloat angleBetweenLinesInDegrees(CGPoint beginLineA, CGPoint endLineA, CGPoint beginLineB, CGPoint endLineB); - (id) initWithMidPoint: (CGPoint) _midPoint innerRadius: (CGFloat) _innerRadius outerRadius: (CGFloat) _outerRadius target: (id <OneFingerRotationGestureRecognizerDelegate>) _target { if ((self = [super initWithTarget: _target action: nil])) { midPoint = _midPoint; innerRadius = _innerRadius; outerRadius = _outerRadius; target = _target; } return self; } /** Calculates the distance between point1 and point 2. */ CGFloat distanceBetweenPoints(CGPoint point1, CGPoint point2) { CGFloat dx = point1.x - point2.x; CGFloat dy = point1.y - point2.y; return sqrt(dx*dx + dy*dy); } CGFloat angleBetweenLinesInDegrees(CGPoint beginLineA, CGPoint endLineA, CGPoint beginLineB, CGPoint endLineB) { CGFloat a = endLineA.x - beginLineA.x; CGFloat b = endLineA.y - beginLineA.y; CGFloat c = endLineB.x - beginLineB.x; CGFloat d = endLineB.y - beginLineB.y; CGFloat atanA = atan2(a, b); CGFloat atanB = atan2(c, d); // convert radiants to degrees return (atanA - atanB) * 180 / M_PI; } #pragma mark - UIGestureRecognizer implementation - (void)reset { [super reset]; cumulatedAngle = 0; } - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { [super touchesBegan:touches withEvent:event]; if ([touches count] != 1) { self.state = UIGestureRecognizerStateFailed; return; } } - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { [super touchesMoved:touches withEvent:event]; if (self.state == UIGestureRecognizerStateFailed) return; CGPoint nowPoint = [[touches anyObject] locationInView: self.view]; CGPoint prevPoint = [[touches anyObject] previousLocationInView: self.view]; // make sure the new point is within the area CGFloat distance = distanceBetweenPoints(midPoint, nowPoint); if ( innerRadius <= distance && distance <= outerRadius) { // calculate rotation angle between two points CGFloat angle = angleBetweenLinesInDegrees(midPoint, prevPoint, midPoint, nowPoint); // fix value, if the 12 o'clock position is between prevPoint and nowPoint if (angle > 180) { angle -= 360; } else if (angle < -180) { angle += 360; } // sum up single steps cumulatedAngle += angle; // call delegate if ([target respondsToSelector: @selector(rotation:)]) { [target rotation:angle]; } } else { // finger moved outside the area self.state = UIGestureRecognizerStateFailed; } } - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event { [super touchesEnded:touches withEvent:event]; if (self.state == UIGestureRecognizerStatePossible) { self.state = UIGestureRecognizerStateRecognized; if ([target respondsToSelector: @selector(finalAngle:)]) { [target finalAngle:cumulatedAngle]; } } else { self.state = UIGestureRecognizerStateFailed; } cumulatedAngle = 0; } - (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event { [super touchesCancelled:touches withEvent:event]; self.state = UIGestureRecognizerStateFailed; cumulatedAngle = 0; } @end Then its initialised like this: // calculate center and radius of the control CGPoint midPoint = CGPointMake(image.frame.origin.x + image.frame.size.width / 2, image.frame.origin.y + image.frame.size.height / 2); CGFloat outRadius = image.frame.size.width / 2; // outRadius / 3 is arbitrary, just choose something >> 0 to avoid strange // effects when touching the control near of it's center gestureRecognizer = [[OneFingerRotationGestureRecognizer alloc] initWithMidPoint: midPoint innerRadius: outRadius / 3 outerRadius: outRadius target: self]; [self.view addGestureRecognizer: gestureRecognizer]; The selector below is also in the same file where the initialisation of the gestureRecogonizer: - (void) rotation: (CGFloat) angle { // calculate rotation angle imageAngle += angle; if (imageAngle > 360) imageAngle -= 360; else if (imageAngle < -360) imageAngle += 360; // rotate image and update text field image.transform = CGAffineTransformMakeRotation(imageAngle * M_PI / 180); [self updateTextDisplay]; } I can't seem to get this working in the RotateGesture class can anyone help me please I've been stuck on this for days now. SECOND EDIT: Here is the users code from SO that was suggested to me: Here is projec on GitHub: SFGestureRecognizers It uses builded in iOS UIGestureRecognizer, and don't needs to be integrated into cocos2d sources. Using it, You can make any gestures, just like you could, if you whould work with UIGestureRecognizer. For example: I made a base class Gesture, and subclassed it for any new gesture: //Gesture.h @interface Gesture : NSObject <UIGestureRecognizerDelegate> { UIGestureRecognizer *gestureRecognizer; id delegate; SEL preSolveSelector; SEL possibleSelector; SEL beganSelector; SEL changedSelector; SEL endedSelector; SEL cancelledSelector; SEL failedSelector; BOOL preSolveAvailable; CCNode *owner; } - (id)init; - (void)addGestureRecognizerToNode:(CCNode*)node; - (void)removeGestureRecognizerFromNode:(CCNode*)node; -(void)recognizer:(UIGestureRecognizer*)recognizer; @end //Gesture.m #import "Gesture.h" @implementation Gesture - (id)init { if (!(self = [super init])) return self; preSolveAvailable = YES; return self; } - (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer { return YES; } - (BOOL)gestureRecognizer:(UIGestureRecognizer *)recognizer shouldReceiveTouch:(UITouch *)touch { //! For swipe gesture recognizer we want it to be executed only if it occurs on the main layer, not any of the subnodes ( main layer is higher in hierarchy than children so it will be receiving touch by default ) if ([recognizer class] == [UISwipeGestureRecognizer class]) { CGPoint pt = [touch locationInView:touch.view]; pt = [[CCDirector sharedDirector] convertToGL:pt]; for (CCNode *child in owner.children) { if ([child isNodeInTreeTouched:pt]) { return NO; } } } return YES; } - (void)addGestureRecognizerToNode:(CCNode*)node { [node addGestureRecognizer:gestureRecognizer]; owner = node; } - (void)removeGestureRecognizerFromNode:(CCNode*)node { [node removeGestureRecognizer:gestureRecognizer]; } #pragma mark - Private methods -(void)recognizer:(UIGestureRecognizer*)recognizer { CCNode *node = recognizer.node; if (preSolveSelector && preSolveAvailable) { preSolveAvailable = NO; [delegate performSelector:preSolveSelector withObject:recognizer withObject:node]; } UIGestureRecognizerState state = [recognizer state]; if (state == UIGestureRecognizerStatePossible && possibleSelector) { [delegate performSelector:possibleSelector withObject:recognizer withObject:node]; } else if (state == UIGestureRecognizerStateBegan && beganSelector) [delegate performSelector:beganSelector withObject:recognizer withObject:node]; else if (state == UIGestureRecognizerStateChanged && changedSelector) [delegate performSelector:changedSelector withObject:recognizer withObject:node]; else if (state == UIGestureRecognizerStateEnded && endedSelector) { preSolveAvailable = YES; [delegate performSelector:endedSelector withObject:recognizer withObject:node]; } else if (state == UIGestureRecognizerStateCancelled && cancelledSelector) { preSolveAvailable = YES; [delegate performSelector:cancelledSelector withObject:recognizer withObject:node]; } else if (state == UIGestureRecognizerStateFailed && failedSelector) { preSolveAvailable = YES; [delegate performSelector:failedSelector withObject:recognizer withObject:node]; } } @end Subclass example: //RotateGesture.h #import "Gesture.h" @interface RotateGesture : Gesture - (id)initWithTarget:(id)target preSolveSelector:(SEL)preSolve possibleSelector:(SEL)possible beganSelector:(SEL)began changedSelector:(SEL)changed endedSelector:(SEL)ended cancelledSelector:(SEL)cancelled failedSelector:(SEL)failed; @end //RotateGesture.m #import "RotateGesture.h" @implementation RotateGesture - (id)initWithTarget:(id)target preSolveSelector:(SEL)preSolve possibleSelector:(SEL)possible beganSelector:(SEL)began changedSelector:(SEL)changed endedSelector:(SEL)ended cancelledSelector:(SEL)cancelled failedSelector:(SEL)failed { if (!(self = [super init])) return self; preSolveSelector = preSolve; delegate = target; possibleSelector = possible; beganSelector = began; changedSelector = changed; endedSelector = ended; cancelledSelector = cancelled; failedSelector = failed; gestureRecognizer = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(recognizer:)]; gestureRecognizer.delegate = self; return self; } @end Use example: - (void)addRotateGesture { RotateGesture *rotateRecognizer = [[RotateGesture alloc] initWithTarget:self preSolveSelector:@selector(rotateGesturePreSolveWithRecognizer:node:) possibleSelector:nil beganSelector:@selector(rotateGestureStateBeganWithRecognizer:node:) changedSelector:@selector(rotateGestureStateChangedWithRecognizer:node:) endedSelector:@selector(rotateGestureStateEndedWithRecognizer:node:) cancelledSelector:@selector(rotateGestureStateCancelledWithRecognizer:node:) failedSelector:@selector(rotateGestureStateFailedWithRecognizer:node:)]; [rotateRecognizer addGestureRecognizerToNode:movableAreaSprite]; } I dont understand how to implement the custom gesture code at the start of this post into the rotateGesture class which is a subclass of the gesture class written by the SO user. Any ideas please? When I get 6 more rep I'll add a bounty to this.

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• Scrolling an HTML 5 page using JQuery

  - by nikolaosk

  In this post I will show you how to use JQuery to scroll through an HTML 5 page.I had to help a friend of mine to implement this functionality and I thought it would be a good idea to write a post.I will not use any JQuery scrollbar plugin,I will just use the very popular JQuery Library. Please download the library (minified version) from http://jquery.com/download.Please find here all my posts regarding JQuery.Also have a look at my posts regarding HTML 5.In order to be absolutely clear this is not (and could not be) a detailed tutorial on HTML 5. There are other great resources for that.Navigate to the excellent interactive tutorials of W3School.Another excellent resource is HTML 5 Doctor.Two very nice sites that show you what features and specifications are implemented by various browsers and their versions are http://caniuse.com/ and http://html5test.com/. At this times Chrome seems to support most of HTML 5 specifications.Another excellent way to find out if the browser supports HTML 5 and CSS 3 features is to use the Javascript lightweight library Modernizr.In this hands-on example I will be using Expression Web 4.0.This application is not a free application. You can use any HTML editor you like.You can use Visual Studio 2012 Express edition. You can download it here. Let me move on to the actual example.This is the sample HTML 5 page<!DOCTYPE html><html lang="en">  <head>    <title>Liverpool Legends</title>        <meta http-equiv="Content-Type" content="text/html;charset=utf-8" >        <link rel="stylesheet" type="text/css" href="style.css">        <script type="text/javascript" src="jquery-1.8.2.min.js"> </script>     <script type="text/javascript" src="scroll.js">     </script>       </head>  <body>    <header>        <h1>Liverpool Legends</h1>    </header>        <div id="main">        <table>        <caption>Liverpool Players</caption>        <thead>            <tr>                <th>Name</th>                <th>Photo</th>                <th>Position</th>                <th>Age</th>                <th>Scroll</th>            </tr>        </thead>        <tfoot class="footnote">            <tr>                <td colspan="4">We will add more photos soon</td>            </tr>        </tfoot>    <tbody>        <tr class="maintop">        <td>Alan Hansen</td>            <td>            <figure>            <img src="images\Alan-hansen-large.jpg" alt="Alan Hansen">            <figcaption>The best Liverpool Defender <a href="http://en.wikipedia.org/wiki/Alan_Hansen">Alan Hansen</a></figcaption>            </figure>            </td>            <td>Defender</td>            <td>57</td>            <td class="top">Middle</td>        </tr>        <tr>        <td>Graeme Souness</td>            <td>            <figure>            <img src="images\graeme-souness-large.jpg" alt="Graeme Souness">            <figcaption>Souness was the captain of the successful Liverpool team of the early 1980s <a href="http://en.wikipedia.org/wiki/Graeme_Souness">Graeme Souness</a></figcaption>            </figure>            </td>            <td>MidFielder</td>            <td>59</td>        </tr>        <tr>        <td>Ian Rush</td>            <td>            <figure>            <img src="images\ian-rush-large.jpg" alt="Ian Rush">            <figcaption>The deadliest Liverpool Striker <a href="http://it.wikipedia.org/wiki/Ian_Rush">Ian Rush</a></figcaption>            </figure>            </td>            <td>Striker</td>            <td>51</td>        </tr>        <tr class="mainmiddle">        <td>John Barnes</td>            <td>            <figure>            <img src="images\john-barnes-large.jpg" alt="John Barnes">            <figcaption>The best Liverpool Defender <a href="http://en.wikipedia.org/wiki/John_Barnes_(footballer)">John Barnes</a></figcaption>            </figure>            </td>            <td>MidFielder</td>            <td>49</td>            <td class="middle">Bottom</td>        </tr>                <tr>        <td>Kenny Dalglish</td>            <td>            <figure>            <img src="images\kenny-dalglish-large.jpg" alt="Kenny Dalglish">            <figcaption>King Kenny <a href="http://en.wikipedia.org/wiki/Kenny_Dalglish">Kenny Dalglish</a></figcaption>            </figure>            </td>            <td>Midfielder</td>            <td>61</td>        </tr>        <tr>            <td>Michael Owen</td>            <td>            <figure>            <img src="images\michael-owen-large.jpg" alt="Michael Owen">            <figcaption>Michael was Liverpool's top goal scorer from 1997–2004 <a href="http://www.michaelowen.com/">Michael Owen</a></figcaption>            </figure>            </td>            <td>Striker</td>            <td>33</td>        </tr>        <tr>            <td>Robbie Fowler</td>            <td>            <figure>            <img src="images\robbie-fowler-large.jpg" alt="Robbie Fowler">            <figcaption>Fowler scored 183 goals in total for Liverpool <a href="http://en.wikipedia.org/wiki/Robbie_Fowler">Robbie Fowler</a></figcaption>            </figure>            </td>            <td>Striker</td>            <td>38</td>        </tr>        <tr class="mainbottom">            <td>Steven Gerrard</td>            <td>            <figure>            <img src="images\steven-gerrard-large.jpg" alt="Steven Gerrard">            <figcaption>Liverpool's captain <a href="http://en.wikipedia.org/wiki/Steven_Gerrard">Steven Gerrard</a></figcaption>            </figure>            </td>            <td>Midfielder</td>            <td>32</td>            <td class="bottom">Top</td>        </tr>    </tbody></table>          </div>            <footer>        <p>All Rights Reserved</p>      </footer>     </body>  </html>  The markup is very easy to follow and understand. You do not have to type all the code,simply copy and paste it.For those that you are not familiar with HTML 5, please take a closer look at the new tags/elements introduced with HTML 5.When I view the HTML 5 page with Firefox I see the following result. I have also an external stylesheet (style.css). body{background-color:#efefef;}h1{font-size:2.3em;}table { border-collapse: collapse;font-family: Futura, Arial, sans-serif; }caption { font-size: 1.2em; margin: 1em auto; }th, td {padding: .65em; }th, thead { background: #000; color: #fff; border: 1px solid #000; }tr:nth-child(odd) { background: #ccc; }tr:nth-child(even) { background: #404040; }td { border-right: 1px solid #777; }table { border: 1px solid #777;  }.top, .middle, .bottom {    cursor: pointer;    font-size: 22px;    font-weight: bold;    text-align: center;}.footnote{text-align:center;font-family:Tahoma;color:#EB7515;}a{color:#22577a;text-decoration:none;}     a:hover {color:#125949; text-decoration:none;}  footer{background-color:#505050;width:1150px;}These are just simple CSS Rules that style the various HTML 5 tags,classes. The jQuery code that makes it all possible resides inside the scroll.js file.Make sure you type everything correctly.$(document).ready(function() {                 $('.top').click(function(){                     $('html, body').animate({                         scrollTop: $(".mainmiddle").offset().top                     },4000 );                  });                 $('.middle').click(function(){                     $('html, body').animate({                         scrollTop: $(".mainbottom").offset().top                     },4000);                  });                     $('.bottom').click(function(){                     $('html, body').animate({                         scrollTop: $(".maintop").offset().top                     },4000);                  }); });  Let me explain what I am doing here.When I click on the Middle word (  $('.top').click(function(){ ) this relates to the top class that is clicked.Then we declare the elements that we want to participate in the scrolling. In this case is html,body ( $('html, body').animate).These elements will be part of the vertical scrolling.In the next line of code we simply move (navigate) to the element (class mainmiddle that is attached to a tr element.)      scrollTop: $(".mainmiddle").offset().top  Make sure you type all the code correctly and try it for yourself. I have tested this solution will all 4-5 major browsers.Hope it helps!!!

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• evaluating a code of a graph [migrated]

  - by mazen.r.f

  This is relatively a long code,if you have the tolerance and the will to find out how to make this code work then take a look please, i will appreciate your feed back. i have spent two days trying to come up with a code to represent a graph , then calculate the shortest path using dijkastra algorithm , but i am not able to get the right result , even the code runs without errors , but the result is not correct , always i am getting 0. briefly,i have three classes , Vertex, Edge, Graph , the Vertex class represents the nodes in the graph and it has id and carried ( which carry the weight of the links connected to it while using dijkastra algorithm ) and a vector of the ids belong to other nodes the path will go through before arriving to the node itself , this vector is named previous_nodes. the Edge class represents the edges in the graph it has two vertices ( one in each side ) and a wight ( the distance between the two vertices ). the Graph class represents the graph , it has two vectors one is the vertices included in this graph , and the other is the edges included in the graph. inside the class Graph there is a method its name shortest takes the sources node id and the destination and calculates the shortest path using dijkastra algorithm, and i think that it is the most important part of the code. my theory about the code is that i will create two vectors one for the vertices in the graph i will name it vertices and another vector its name is ver_out it will include the vertices out of calculation in the graph, also i will have two vectors of type Edge , one its name edges for all the edges in the graph and the other its name is track to contain temporarily the edges linked to the temporarily source node in every round , after the calculation of every round the vector track will be cleared. in main() i created five vertices and 10 edges to simulate a graph , the result of the shortest path supposedly to be 4 , but i am always getting 0 , that means i am having something wrong in my code , so if you are interesting in helping me find my mistake and how to make the code work , please take a look. the way shortest work is as follow at the beginning all the edges will be included in the vector edges , we select the edges related to the source and put them in the vector track , then we iterate through track and add the wight of every edge to the vertex (node ) related to it ( not the source vertex ) , then after we clear track and remove the source vertex from the vector vertices and select a new source , and start over again select the edges related to the new source , put them in track , iterate over edges in tack , adding the weights to the corresponding vertices then remove this vertex from the vector vertices, and clear track , and select a new source , and so on . here is the code. #include<iostream> #include<vector> #include <stdlib.h> // for rand() using namespace std; class Vertex { private: unsigned int id; // the name of the vertex unsigned int carried; // the weight a vertex may carry when calculating shortest path vector<unsigned int> previous_nodes; public: unsigned int get_id(){return id;}; unsigned int get_carried(){return carried;}; void set_id(unsigned int value) {id = value;}; void set_carried(unsigned int value) {carried = value;}; void previous_nodes_update(unsigned int val){previous_nodes.push_back(val);}; void previous_nodes_erase(unsigned int val){previous_nodes.erase(previous_nodes.begin() + val);}; Vertex(unsigned int init_val = 0, unsigned int init_carried = 0) :id (init_val), carried(init_carried) // constructor { } ~Vertex() {}; // destructor }; class Edge { private: Vertex first_vertex; // a vertex on one side of the edge Vertex second_vertex; // a vertex on the other side of the edge unsigned int weight; // the value of the edge ( or its weight ) public: unsigned int get_weight() {return weight;}; void set_weight(unsigned int value) {weight = value;}; Vertex get_ver_1(){return first_vertex;}; Vertex get_ver_2(){return second_vertex;}; void set_first_vertex(Vertex v1) {first_vertex = v1;}; void set_second_vertex(Vertex v2) {second_vertex = v2;}; Edge(const Vertex& vertex_1 = 0, const Vertex& vertex_2 = 0, unsigned int init_weight = 0) : first_vertex(vertex_1), second_vertex(vertex_2), weight(init_weight) { } ~Edge() {} ; // destructor }; class Graph { private: std::vector<Vertex> vertices; std::vector<Edge> edges; public: Graph(vector<Vertex> ver_vector, vector<Edge> edg_vector) : vertices(ver_vector), edges(edg_vector) { } ~Graph() {}; vector<Vertex> get_vertices(){return vertices;}; vector<Edge> get_edges(){return edges;}; void set_vertices(vector<Vertex> vector_value) {vertices = vector_value;}; void set_edges(vector<Edge> vector_ed_value) {edges = vector_ed_value;}; unsigned int shortest(unsigned int src, unsigned int dis) { vector<Vertex> ver_out; vector<Edge> track; for(unsigned int i = 0; i < edges.size(); ++i) { if((edges[i].get_ver_1().get_id() == vertices[src].get_id()) || (edges[i].get_ver_2().get_id() == vertices[src].get_id())) { track.push_back (edges[i]); edges.erase(edges.begin()+i); } }; for(unsigned int i = 0; i < track.size(); ++i) { if(track[i].get_ver_1().get_id() != vertices[src].get_id()) { track[i].get_ver_1().set_carried((track[i].get_weight()) + track[i].get_ver_2().get_carried()); track[i].get_ver_1().previous_nodes_update(vertices[src].get_id()); } else { track[i].get_ver_2().set_carried((track[i].get_weight()) + track[i].get_ver_1().get_carried()); track[i].get_ver_2().previous_nodes_update(vertices[src].get_id()); } } for(unsigned int i = 0; i < vertices.size(); ++i) if(vertices[i].get_id() == src) vertices.erase(vertices.begin() + i); // removing the sources vertex from the vertices vector ver_out.push_back (vertices[src]); track.clear(); if(vertices[0].get_id() != dis) {src = vertices[0].get_id();} else {src = vertices[1].get_id();} for(unsigned int i = 0; i < vertices.size(); ++i) if((vertices[i].get_carried() < vertices[src].get_carried()) && (vertices[i].get_id() != dis)) src = vertices[i].get_id(); //while(!edges.empty()) for(unsigned int round = 0; round < vertices.size(); ++round) { for(unsigned int k = 0; k < edges.size(); ++k) { if((edges[k].get_ver_1().get_id() == vertices[src].get_id()) || (edges[k].get_ver_2().get_id() == vertices[src].get_id())) { track.push_back (edges[k]); edges.erase(edges.begin()+k); } }; for(unsigned int n = 0; n < track.size(); ++n) if((track[n].get_ver_1().get_id() != vertices[src].get_id()) && (track[n].get_ver_1().get_carried() > (track[n].get_ver_2().get_carried() + track[n].get_weight()))) { track[n].get_ver_1().set_carried((track[n].get_weight()) + track[n].get_ver_2().get_carried()); track[n].get_ver_1().previous_nodes_update(vertices[src].get_id()); } else if(track[n].get_ver_2().get_carried() > (track[n].get_ver_1().get_carried() + track[n].get_weight())) { track[n].get_ver_2().set_carried((track[n].get_weight()) + track[n].get_ver_1().get_carried()); track[n].get_ver_2().previous_nodes_update(vertices[src].get_id()); } for(unsigned int t = 0; t < vertices.size(); ++t) if(vertices[t].get_id() == src) vertices.erase(vertices.begin() + t); track.clear(); if(vertices[0].get_id() != dis) {src = vertices[0].get_id();} else {src = vertices[1].get_id();} for(unsigned int tt = 0; tt < edges.size(); ++tt) { if(vertices[tt].get_carried() < vertices[src].get_carried()) { src = vertices[tt].get_id(); } } } return vertices[dis].get_carried(); } }; int main() { cout<< "Hello, This is a graph"<< endl; vector<Vertex> vers(5); vers[0].set_id(0); vers[1].set_id(1); vers[2].set_id(2); vers[3].set_id(3); vers[4].set_id(4); vector<Edge> eds(10); eds[0].set_first_vertex(vers[0]); eds[0].set_second_vertex(vers[1]); eds[0].set_weight(5); eds[1].set_first_vertex(vers[0]); eds[1].set_second_vertex(vers[2]); eds[1].set_weight(9); eds[2].set_first_vertex(vers[0]); eds[2].set_second_vertex(vers[3]); eds[2].set_weight(4); eds[3].set_first_vertex(vers[0]); eds[3].set_second_vertex(vers[4]); eds[3].set_weight(6); eds[4].set_first_vertex(vers[1]); eds[4].set_second_vertex(vers[2]); eds[4].set_weight(2); eds[5].set_first_vertex(vers[1]); eds[5].set_second_vertex(vers[3]); eds[5].set_weight(5); eds[6].set_first_vertex(vers[1]); eds[6].set_second_vertex(vers[4]); eds[6].set_weight(7); eds[7].set_first_vertex(vers[2]); eds[7].set_second_vertex(vers[3]); eds[7].set_weight(1); eds[8].set_first_vertex(vers[2]); eds[8].set_second_vertex(vers[4]); eds[8].set_weight(8); eds[9].set_first_vertex(vers[3]); eds[9].set_second_vertex(vers[4]); eds[9].set_weight(3); unsigned int path; Graph graf(vers, eds); path = graf.shortest(2, 4); cout<< path << endl; return 0; }

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• Evaluating code for a graph [migrated]

  - by mazen.r.f

  This is relatively long code. Please take a look at this code if you are still willing to do so. I will appreciate your feedback. I have spent two days trying to come up with code to represent a graph, calculating the shortest path using Dijkstra's algorithm. But I am not able to get the right result, even though the code runs without errors. The result is not correct and I am always getting 0. I have three classes: Vertex, Edge, and Graph. The Vertex class represents the nodes in the graph and it has id and carried (which carry the weight of the links connected to it while using Dijkstra's algorithm) and a vector of the ids belong to other nodes the path will go through before arriving to the node itself. This vector is named previous_nodes. The Edge class represents the edges in the graph and has two vertices (one in each side) and a width (the distance between the two vertices). The Graph class represents the graph. It has two vectors, where one is the vertices included in this graph, and the other is the edges included in the graph. Inside the class Graph, there is a method named shortest() that takes the sources node id and the destination and calculates the shortest path using Dijkstra's algorithm. I think that it is the most important part of the code. My theory about the code is that I will create two vectors, one for the vertices in the graph named vertices, and another vector named ver_out (it will include the vertices out of calculation in the graph). I will also have two vectors of type Edge, where one is named edges (for all the edges in the graph), and the other is named track (to temporarily contain the edges linked to the temporary source node in every round). After the calculation of every round, the vector track will be cleared. In main(), I've created five vertices and 10 edges to simulate a graph. The result of the shortest path supposedly is 4, but I am always getting 0. That means I have something wrong in my code. If you are interesting in helping me find my mistake and making the code work, please take a look. The way shortest work is as follow: at the beginning, all the edges will be included in the vector edges. We select the edges related to the source and put them in the vector track, then we iterate through track and add the width of every edge to the vertex (node) related to it (not the source vertex). After that, we clear track and remove the source vertex from the vector vertices and select a new source. Then we start over again and select the edges related to the new source, put them in track, iterate over edges in track, adding the weights to the corresponding vertices, then remove this vertex from the vector vertices. Then clear track, and select a new source, and so on. #include<iostream> #include<vector> #include <stdlib.h> // for rand() using namespace std; class Vertex { private: unsigned int id; // the name of the vertex unsigned int carried; // the weight a vertex may carry when calculating shortest path vector<unsigned int> previous_nodes; public: unsigned int get_id(){return id;}; unsigned int get_carried(){return carried;}; void set_id(unsigned int value) {id = value;}; void set_carried(unsigned int value) {carried = value;}; void previous_nodes_update(unsigned int val){previous_nodes.push_back(val);}; void previous_nodes_erase(unsigned int val){previous_nodes.erase(previous_nodes.begin() + val);}; Vertex(unsigned int init_val = 0, unsigned int init_carried = 0) :id (init_val), carried(init_carried) // constructor { } ~Vertex() {}; // destructor }; class Edge { private: Vertex first_vertex; // a vertex on one side of the edge Vertex second_vertex; // a vertex on the other side of the edge unsigned int weight; // the value of the edge ( or its weight ) public: unsigned int get_weight() {return weight;}; void set_weight(unsigned int value) {weight = value;}; Vertex get_ver_1(){return first_vertex;}; Vertex get_ver_2(){return second_vertex;}; void set_first_vertex(Vertex v1) {first_vertex = v1;}; void set_second_vertex(Vertex v2) {second_vertex = v2;}; Edge(const Vertex& vertex_1 = 0, const Vertex& vertex_2 = 0, unsigned int init_weight = 0) : first_vertex(vertex_1), second_vertex(vertex_2), weight(init_weight) { } ~Edge() {} ; // destructor }; class Graph { private: std::vector<Vertex> vertices; std::vector<Edge> edges; public: Graph(vector<Vertex> ver_vector, vector<Edge> edg_vector) : vertices(ver_vector), edges(edg_vector) { } ~Graph() {}; vector<Vertex> get_vertices(){return vertices;}; vector<Edge> get_edges(){return edges;}; void set_vertices(vector<Vertex> vector_value) {vertices = vector_value;}; void set_edges(vector<Edge> vector_ed_value) {edges = vector_ed_value;}; unsigned int shortest(unsigned int src, unsigned int dis) { vector<Vertex> ver_out; vector<Edge> track; for(unsigned int i = 0; i < edges.size(); ++i) { if((edges[i].get_ver_1().get_id() == vertices[src].get_id()) || (edges[i].get_ver_2().get_id() == vertices[src].get_id())) { track.push_back (edges[i]); edges.erase(edges.begin()+i); } }; for(unsigned int i = 0; i < track.size(); ++i) { if(track[i].get_ver_1().get_id() != vertices[src].get_id()) { track[i].get_ver_1().set_carried((track[i].get_weight()) + track[i].get_ver_2().get_carried()); track[i].get_ver_1().previous_nodes_update(vertices[src].get_id()); } else { track[i].get_ver_2().set_carried((track[i].get_weight()) + track[i].get_ver_1().get_carried()); track[i].get_ver_2().previous_nodes_update(vertices[src].get_id()); } } for(unsigned int i = 0; i < vertices.size(); ++i) if(vertices[i].get_id() == src) vertices.erase(vertices.begin() + i); // removing the sources vertex from the vertices vector ver_out.push_back (vertices[src]); track.clear(); if(vertices[0].get_id() != dis) {src = vertices[0].get_id();} else {src = vertices[1].get_id();} for(unsigned int i = 0; i < vertices.size(); ++i) if((vertices[i].get_carried() < vertices[src].get_carried()) && (vertices[i].get_id() != dis)) src = vertices[i].get_id(); //while(!edges.empty()) for(unsigned int round = 0; round < vertices.size(); ++round) { for(unsigned int k = 0; k < edges.size(); ++k) { if((edges[k].get_ver_1().get_id() == vertices[src].get_id()) || (edges[k].get_ver_2().get_id() == vertices[src].get_id())) { track.push_back (edges[k]); edges.erase(edges.begin()+k); } }; for(unsigned int n = 0; n < track.size(); ++n) if((track[n].get_ver_1().get_id() != vertices[src].get_id()) && (track[n].get_ver_1().get_carried() > (track[n].get_ver_2().get_carried() + track[n].get_weight()))) { track[n].get_ver_1().set_carried((track[n].get_weight()) + track[n].get_ver_2().get_carried()); track[n].get_ver_1().previous_nodes_update(vertices[src].get_id()); } else if(track[n].get_ver_2().get_carried() > (track[n].get_ver_1().get_carried() + track[n].get_weight())) { track[n].get_ver_2().set_carried((track[n].get_weight()) + track[n].get_ver_1().get_carried()); track[n].get_ver_2().previous_nodes_update(vertices[src].get_id()); } for(unsigned int t = 0; t < vertices.size(); ++t) if(vertices[t].get_id() == src) vertices.erase(vertices.begin() + t); track.clear(); if(vertices[0].get_id() != dis) {src = vertices[0].get_id();} else {src = vertices[1].get_id();} for(unsigned int tt = 0; tt < edges.size(); ++tt) { if(vertices[tt].get_carried() < vertices[src].get_carried()) { src = vertices[tt].get_id(); } } } return vertices[dis].get_carried(); } }; int main() { cout<< "Hello, This is a graph"<< endl; vector<Vertex> vers(5); vers[0].set_id(0); vers[1].set_id(1); vers[2].set_id(2); vers[3].set_id(3); vers[4].set_id(4); vector<Edge> eds(10); eds[0].set_first_vertex(vers[0]); eds[0].set_second_vertex(vers[1]); eds[0].set_weight(5); eds[1].set_first_vertex(vers[0]); eds[1].set_second_vertex(vers[2]); eds[1].set_weight(9); eds[2].set_first_vertex(vers[0]); eds[2].set_second_vertex(vers[3]); eds[2].set_weight(4); eds[3].set_first_vertex(vers[0]); eds[3].set_second_vertex(vers[4]); eds[3].set_weight(6); eds[4].set_first_vertex(vers[1]); eds[4].set_second_vertex(vers[2]); eds[4].set_weight(2); eds[5].set_first_vertex(vers[1]); eds[5].set_second_vertex(vers[3]); eds[5].set_weight(5); eds[6].set_first_vertex(vers[1]); eds[6].set_second_vertex(vers[4]); eds[6].set_weight(7); eds[7].set_first_vertex(vers[2]); eds[7].set_second_vertex(vers[3]); eds[7].set_weight(1); eds[8].set_first_vertex(vers[2]); eds[8].set_second_vertex(vers[4]); eds[8].set_weight(8); eds[9].set_first_vertex(vers[3]); eds[9].set_second_vertex(vers[4]); eds[9].set_weight(3); unsigned int path; Graph graf(vers, eds); path = graf.shortest(2, 4); cout<< path << endl; return 0; }

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• Code Behaviour via Unit Tests

  - by Dewald Galjaard

  Normal 0 false false false EN-ZA X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Some four months ago my car started acting up. Symptoms included a sputtering as my car’s computer switched between gears intermittently. Imagine building up speed, then when you reach 80km/h the car magically and mysteriously decide to switch back to third or even second gear. Clearly it was confused! I managed to track down a technician, an expert in his field to help me out. As he fitted his handheld computer to some hidden port under the dash, he started to explain “These cars are quite intelligent, you know. When they sense something is wrong they run in a restrictive program which probably account for how you managed to drive here in the first place...”  I was surprised and thought this was certainly going to be an interesting test drive. The car ran smoothly down the first couple of stretches as the technician ran through routine checks. Then he said “Ok, all looking good. We need to start testing aspects of the gearbox. Inside the gearbox there are a couple of sensors. One of them is a speed sensor which talks to the computer, which in turn will decide which gear to switch to. The restrictive program avoid these sensors altogether and allow the computer to obtain its input from other [non-affected] sources”. Then, as soon as he forced the speed sensor to come back online the symptoms and ill behaviour re-emerged... What an incredible analogy for getting into a discussion on unit testing software? Besides I should probably put my ill fortune to some good use, right? This example provide a lot of insight into how and why we should conduct unit tests when writing code. More importantly, it captures what is easily and unfortunately often the most overlooked goal of writing unit tests by those new to the art and those who oppose it alike - The goal of writing unit tests is to test the behaviour of our code under predefined conditions. Although it is very possible to test the intrinsic workings of each and every component in your code, writing several tests for each method in practise will soon prove to be an exhausting and ultimately fruitless exercise given the certain and ever changing nature of business requirements. Consequently it is true and quite possible whilst conducting proper unit tests, to call any single method several times as you examine and contemplate different scenarios. Let’s write some code to demonstrate what I mean. In my example I make use of the Moq framework and NUnit to create my tests. Truly you can use whatever you’re comfortable with. First we’ll create an ISpeedSensor interface. This is to represent the speed sensor located in the gearbox.  Then we’ll create a Gearbox class which we’ll pass to a constructor when we instantiate an object of type Computer. All three are described below.   ISpeedSensor.cs namespace AutomaticVehicle {     public interface ISpeedSensor     {         int ReportCurrentSpeed();     } }   Gearbox.cs namespace AutomaticVehicle {      public class Gearbox     {         private ISpeedSensor _speedSensor;           public Gearbox( ISpeedSensor gearboxSpeedSensor )         {             _speedSensor = gearboxSpeedSensor;         }         /// <summary>         /// This method obtain it's reading from the speed sensor.         /// </summary>         /// <returns></returns>         public int ReportCurrentSpeed()         {             return _speedSensor.ReportCurrentSpeed();         }     } } Computer.cs namespace AutomaticVehicle {     public class Computer     {         private Gearbox _gearbox;         public Computer( Gearbox gearbox )         {                     }          public int GetCurrentSpeed()         {             return _gearbox.ReportCurrentSpeed( );         }     } } Since this post is about Unit testing, that is exactly what we’ll create next. Create a second project in your solution. I called mine AutomaticVehicleTests and I immediately referenced the respective nunit, moq and AutomaticVehicle dll’s. We’re going to write a test to examine what happens inside the Computer class. ComputerTests.cs namespace AutomaticVehicleTests {     [TestFixture]     public class ComputerTests     {         [Test]         public void Computer_Gearbox_SpeedSensor_DoesThrow()         {             // Mock ISpeedSensor in gearbox             Mock< ISpeedSensor > speedSensor = new Mock< ISpeedSensor >( );             speedSensor.Setup( n => n.ReportCurrentSpeed() ).Throws<Exception>();             Gearbox gearbox = new Gearbox( speedSensor.Object );               // Create Computer instance to test it's behaviour  towards an exception in gearbox             Computer carComputer = new Computer( gearbox );             // For simplicity let’s assume for now the car only travels at 60 km/h.             Assert.AreEqual( 60, carComputer.GetCurrentSpeed( ) );          }     } }   What is happening in this test? We have created a mocked object using the ISpeedsensor interface which we've passed to our Gearbox object. Notice that I created the mocked object using an interface, not the implementation. I’ll talk more about this in future posts but in short I do this to accentuate the fact that I'm not not really concerned with how SpeedSensor work internally at this particular point in time. Next I’ve gone ahead and created a scenario where I’ve declared the speed sensor in Gearbox to be faulty by forcing it to throw an exception should we ask Gearbox to report on its current speed. Sneaky, sneaky. This test is a simulation of how things may behave in the real world. Inevitability things break, whether it’s caused by mechanical failure, some logical error on your part or a fellow developer which didn’t consult the documentation (or the lack thereof ) - whether you’re calling a speed sensor, making a call to a database, calling a web service or just trying to write a file to disk. It’s a scenario I’ve created and this test is about how the code within the Computer instance will behave towards any such error as I’ve depicted. Now, if you’ve followed closely in my final assert method you would have noticed I did something quite unexpected. I might be getting ahead of myself now but I’m testing to see if the value returned is equal to what I expect it to be under perfect conditions – I’m not testing to see if an error has been thrown! Why is that? Well, in short this is TDD. Test Driven Development is about first writing your test to define the result we want, then to go back and change the implementation within your class to obtain the desired output (I need to make sure I can drive back to the repair shop. Remember? ) So let’s go ahead and run our test as is. It’s fails miserably... Good! Let’s go back to our Computer class and make a small change to the GetCurrentSpeed method.   Computer.cs public int GetCurrentSpeed() {   try   {     return _gearbox.ReportCurrentSpeed( );   }   catch   {     RunRestrictiveProgram( );   } }     This is a simple solution, I know, but it does provide a way to allow for different behaviour. You’re more than welcome to provide an implementation for RunRestrictiveProgram should you feel the need to. It's not within the scope of this post or related to the point I'm trying to make. What is important is to notice how the focus has shifted in our approach from how things can break - to how things behave when broken.   Happy coding!

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• Particle and Physics problem.

  - by Quincy

  This was originally a forum post so I hope you guys don't mind it being 2 questions in one. I am making a game and I got some basic physics implemented. I have 2 problems, 1 with particles being drawn in the wrong place and one with going through walls while jumping in corners. Skip over to about 15 sec video showing the 2 problems : http://youtube.com/watch?v=Tm9nfWsWfiM So the problem with the particles seems to be coming from the removal, as soon as I remove that piece of code it instantly works, but there shouldn't be a problem since they shouldn't even draw when their energy gets to 0 (and then they get removed) So my first question is, how are these particles getting warped all over the screen ? Relevant code : Particle class : class Particle { //Physics public Vector2 position = new Vector2(0,0); public float direction = 180; public float speed = 100; public float energy = 1; protected float startEnergy = 1; //Visual public Sprite sprite; public float rotation = 0; public float scale = 1; public byte alpha = 255; public BlendMode blendMode { get { return sprite.BlendMode; } set { sprite.BlendMode = value; } } public Particle() { } public virtual void Think(float frameTime) { if (energy - frameTime < 0) energy = 0; else energy -= frameTime; position += new Vector2((float)Math.Cos(MathHelper.DegToRad(direction)), (float)Math.Sin(MathHelper.DegToRad(direction))) * speed * frameTime; alpha = (byte)(255 * energy / startEnergy); sprite.Rotation = rotation; sprite.Position = position; sprite.Color = new Color(sprite.Color.R, sprite.Color.G, sprite.Color.B, alpha); } public virtual void Draw(float frameTime) { if (energy > 0) { World.camera.DrawSprite(sprite); } } // Basic particle implementation class BasicSprite : Particle { public BasicSprite(Sprite _sprite) { sprite = _sprite; } } Emitter : class Emitter { protected static Random rand = new Random(); protected List<Particle> particles = new List<Particle>(); public BaseEntity target = null; public Vector2 position = new Vector2(0, 0); public bool Active = true; public float timeAlive = 0; public int particleCount = 0; public int ParticlesPerSeccond { get { return (int)(1 / particleSpawnTime); } set { particleSpawnTime = 1 / (float)value; } } public float dieTime = float.MaxValue; float particleSpawnTime = 0.05f; float spawnTime = 0; public Emitter() { } public virtual void Think(float frametime) { spawnTime += frametime; if (dieTime != float.MaxValue) { timeAlive += frametime; if (timeAlive >= dieTime) Active = false; } if (Active) { if (target != null) position = target.Position; while (spawnTime > particleSpawnTime) { spawnTime -= particleSpawnTime; AddParticle(); particleCount++; } } for (int i = 0; i < particles.Count; i++) { particles[i].Think(frametime); if (particles[i].energy <= 0) { particles.Remove(particles[i]); // As soon as this is removed, it works particleCount--; } } } public virtual void AddParticle() { } public virtual void Draw(float frametime) { foreach (Particle particle in particles) { particle.Draw(frametime); } } } class BloodEmitter : Emitter { Image image; public BloodEmitter() { image = new Image(@"Content/Particles/TinyCircle.png"); image.CreateMaskFromColor(new Color(255, 0, 255, 255)); this.dieTime = 0.5f; this.ParticlesPerSeccond = 100; } public override void AddParticle() { Sprite sprite = new Sprite(image); sprite.Color = new Color((byte)(rand.NextDouble() * 255), (byte)(rand.NextDouble() * 255), (byte)(rand.NextDouble() * 255)); BasicSprite particle = new BasicSprite(sprite); particle.direction = (float)rand.NextDouble() * 360; particle.position = position; particle.blendMode = BlendMode.Alpha; particles.Add(particle); } } The seccond problem is the physics problem, for some reason I can get through the right bottom corner while jumping. I think this is coming from me switching animations but I thought I made it compensate for that. Relevant code : PhysicsEntity : class PhysicsEntity : BaseEntity { // Horizontal movement constants protected const float maxHorizontalSpeed = 1000; protected const float horizontalAcceleration = 15; protected const float horizontalDragAir = 0.95f; protected const float horizontalDragGround = 0.95f; // Vertical movement constants protected const float maxVerticalSpeed = 1000; protected const float verticalAcceleration = 20; // Everything needed for movement and correct animations protected float movement = 0; protected bool onGround = false; protected Vector2 Velocity = new Vector2(0, 0); protected float maxSpeed = 0; float lastThink = 0; float thinkTime = 1f/60f; public PhysicsEntity(Vector2 position, Sprite sprite) : base(position, sprite) { } public override void Draw(float frameTime) { base.Draw(frameTime); } public override void Think(float frameTime) { CalculateMovement(frameTime); base.Think(frameTime); } protected void CalculateMovement(float frameTime) { lastThink += frameTime; while (lastThink > thinkTime) { onGround = false; Velocity.X = MathHelper.Clamp(Velocity.X + horizontalAcceleration * movement, -maxHorizontalSpeed, maxHorizontalSpeed); if (onGround) Velocity.X *= horizontalDragGround; else Velocity.X *= horizontalDragAir; if (maxSpeed < Velocity.X) maxSpeed = Velocity.X; Velocity.Y = MathHelper.Clamp(Velocity.Y + verticalAcceleration, -maxVerticalSpeed, maxVerticalSpeed); lastThink -= thinkTime; DoCollisions(thinkTime); DoAnimations(thinkTime); } } public virtual void DoAnimations(float frameTime) { } public void DoCollisions(float frameTime) { Position.Y += Velocity.Y * frameTime; Vector2 tileCollision = GetTileCollision(); if (tileCollision.X != -1 || tileCollision.Y != -1) { Vector2 collisionDepth = CollisionRectangle.DepthIntersection( new Rectangle( tileCollision.X * World.tileEngine.TileWidth, tileCollision.Y * World.tileEngine.TileHeight, World.tileEngine.TileWidth, World.tileEngine.TileHeight ) ); Position.Y += collisionDepth.Y; if (collisionDepth.Y < 0) onGround = true; Velocity.Y = 0; } Position.X += Velocity.X * frameTime; tileCollision = GetTileCollision(); if (tileCollision.X != -1 || tileCollision.Y != -1) { Vector2 collisionDepth = CollisionRectangle.DepthIntersection( new Rectangle( tileCollision.X * World.tileEngine.TileWidth, tileCollision.Y * World.tileEngine.TileHeight, World.tileEngine.TileWidth, World.tileEngine.TileHeight ) ); Position.X += collisionDepth.X; Velocity.X = 0; } } public void DoCollisions(Vector2 difference) { CollisionRectangle.Y = Position.Y - difference.Y; CollisionRectangle.Height += difference.Y; Vector2 tileCollision = GetTileCollision(); if (tileCollision.X != -1 || tileCollision.Y != -1) { Vector2 collisionDepth = CollisionRectangle.DepthIntersection( new Rectangle( tileCollision.X * World.tileEngine.TileWidth, tileCollision.Y * World.tileEngine.TileHeight, World.tileEngine.TileWidth, World.tileEngine.TileHeight ) ); Position.Y += collisionDepth.Y; if (collisionDepth.Y < 0) onGround = true; Velocity.Y = 0; } CollisionRectangle.X = Position.X - difference.X; CollisionRectangle.Width += difference.X; tileCollision = GetTileCollision(); if (tileCollision.X != -1 || tileCollision.Y != -1) { Vector2 collisionDepth = CollisionRectangle.DepthIntersection( new Rectangle( tileCollision.X * World.tileEngine.TileWidth, tileCollision.Y * World.tileEngine.TileHeight, World.tileEngine.TileWidth, World.tileEngine.TileHeight ) ); Position.X += collisionDepth.X; Velocity.X = 0; } } Vector2 GetTileCollision() { int topLeftTileX = (int)(CollisionRectangle.TopLeft.X / World.tileEngine.TileWidth); int topLeftTileY = (int)(CollisionRectangle.TopLeft.Y / World.tileEngine.TileHeight); int BottomRightTileX = (int)(CollisionRectangle.DownRight.X / World.tileEngine.TileWidth); int BottomRightTileY = (int)(CollisionRectangle.DownRight.Y / World.tileEngine.TileHeight); if (CollisionRectangle.DownRight.Y % World.tileEngine.TileHeight == 0) // If your exactly against the tile don't count that as being inside the tile BottomRightTileY -= 1; if (CollisionRectangle.DownRight.X % World.tileEngine.TileWidth == 0) // If your exactly against the tile don't count that as being inside the tile BottomRightTileX -= 1; for (int i = topLeftTileX; i <= BottomRightTileX; i++) { for (int j = topLeftTileY; j <= BottomRightTileY; j++) { if (World.tileEngine.TileIsSolid(i, j)) { return new Vector2(i, j); } } } return new Vector2(-1, -1); } } Player : enum State { Standing, Running, Jumping, Falling, Sliding, WallSlide } class Player : PhysicsEntity { private State state { get { return currentState; } set { if (currentState != value) { currentState = value; animationChanged = true; } } } private State currentState = State.Standing; private BasicEmitter basicEmitter = new BasicEmitter(); public bool flipped; public bool animationChanged = false; protected const float jumpPower = 600; AnimationManager animationManager; Rectangle DrawRectangle; public override Rectangle CollisionRectangle { get { return new Rectangle( Position.X - DrawRectangle.Width / 2f, Position.Y - DrawRectangle.Height / 2f, DrawRectangle.Width, DrawRectangle.Height ); } } public Player(Vector2 position, Sprite sprite) : base(position, sprite) { // Only posted the relevant bit DrawRectangle = animationManager.currentAnimation.drawingRectangle; } public override void Draw(float frameTime) { World.camera.DrawSprite( Sprite, Position + new Vector2(DrawRectangle.X, DrawRectangle.Y), animationManager.currentAnimation.drawingRectangle ); } public override void Think(float frameTime) { //I only posted the relevant stuff if (animationChanged) { // if the animation has changed make sure we compensate for the change in with and height animationChanged = false; DoCollisions(animationManager.getSizeDifference()); } DoCustomMovement(); base.Think(frameTime); if (!onGround && Velocity.Y > 0) { state = State.Falling; } } void DoCustomMovement() { if (onGround) { if (World.renderWindow.Input.IsKeyDown(KeyCode.W)) { Velocity.Y = -jumpPower; state = State.Jumping; } } } public override void DoAnimations(float frameTime) { string stateName = Enum.GetName(typeof(State), state); if (!animationManager.currentAnimationIs(stateName)) { animationManager.PlayAnimation(stateName); } animationManager.Think(frameTime); DrawRectangle = animationManager.currentAnimation.drawingRectangle; Sprite.Center = new Vector2( DrawRectangle.X + DrawRectangle.Width / 2, DrawRectangle.Y + DrawRectangle.Height / 2 ); Sprite.FlipX(flipped); } So why am I warping through walls ? I have given this some thought but I just can't seem to find out why this is happening. Full source if needed : source : http://www.mediafire.com/?rc7ddo09gnr68zd (download link)

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• ASP.Net MVC Interview Questions and Answers

  - by Samir R. Bhogayta

  About ASP.Net MVC The ASP.Net MVC is the framework provided by Microsoft that lets you develop the applications that follows the principles of Model-View-Controller (MVC) design pattern. The .Net programmers new to MVC thinks that it is similar to WebForms Model (Normal ASP.Net), but it is far different from the WebForms programming.  This article will tell you how to quick learn the basics of MVC along with some frequently asked interview questions and answers on ASP.Net MVC 1. What is ASP.Net MVC The ASP.Net MVC is the framework provided by Microsoft to achieve     separation of concerns that leads to easy maintainability of the     application. Model is supposed to handle data related activity View deals with user interface related work Controller is meant for managing the application flow by communicating between Model and View. Normal 0 false false false EN-US X-NONE X-NONE 2. Why to use ASP.Net MVC The strength of MVC (i.e. ASP.Net MVC) listed below will answer this question MVC reduces the dependency between the components; this makes your code more testable. MVC does not recommend use of server controls, hence the processing time required to generate HTML response is drastically reduced. The integration of java script libraries like jQuery, Microsoft MVC becomes easy as compared to Webforms approach. 3. What do you mean by Razor The Razor is the new View engine introduced in MVC 3.0. The View engine is responsible for processing the view files [e.g. .aspx, .cshtml] in order to generate HTML response. The previous versions of MVC were dependent on ASPX view engine.  4. Can we use ASPX view engine in latest versions of MVC Yes. The Recommended way is to prefer Razor View 5. What are the benefits of Razor View?      The syntax for server side code is simplified      The length of code is drastically reduced      Razor syntax is easy to learn and reduces the complexity Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;} 6. What is the extension of Razor View file? .cshtml (for c#) and .vbhtml (for vb) 7. How to create a Controller in MVC Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;} Create a simple class and extend it from Controller class. The bare minimum requirement for a class to become a controller is to inherit it from ControllerBase is the class that is required to inherit to create the controller but Controller class inherits from ControllerBase. 8. How to create an Action method in MVC Add a simple method inside a controller class with ActionResult return type. 9. How to access a view on the server    The browser generates the request in which the information like Controller name, Action Name and Parameters are provided, when server receives this URL it resolves the Name of Controller and Action, after that it calls the specified action with provided parameters. Action normally does some processing and returns the ViewResult by specifying the view name (blank name searches according to naming conventions).   10. What is the default Form method (i.e. GET, POST) for an action method GET. To change this you can add an action level attribute e.g [HttpPost] Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;} 11. What is a Filter in MVC? When user (browser) sends a request to server an action method of a controller gets invoked; sometimes you may require executing a custom code before or after action method gets invoked, this custom code is called as Filter. 12. What are the different types of Filters in MVC? a. Authorization filter b. Action filter c. Result filter d. Exception filter [Do not forget the order mentioned above as filters gets executed as per above mentioned sequence] 13. Explain the use of Filter with an example? Suppose you are working on a MVC application where URL is sent in an encrypted format instead of a plain text, once encrypted URL is received by server it will ignore action parameters because of URL encryption. To solve this issue you can create global action filter by overriding OnActionExecuting method of controller class, in this you can extract the action parameters from the encrypted URL and these parameters can be set on filterContext to send plain text parameters to the actions.     14. What is a HTML helper? A HTML helper is a method that returns string; return string usually is the HTML tag. The standard HTML helpers (e.g. Html.BeginForm(),Html.TextBox()) available in MVC are lightweight as it does not rely on event model or view state as that of in ASP.Net server controls.

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• Extended URL php

  - by web.ask

  I have a problem with the extended url here in php. I'm not even sure if it's called extended url. I was wondering if someone can help me since i'm no good with PHP. I have a php page the careers.php it shows the career listing but when I click on Learn more link it goes to http(dot)localhost/houseofpatel/jobs/4/Career-4 but it outputs an "Object not found". Does xampplite have something to do with this? or is it just the codes? I also have the breadcrumb.php in here. Please see code below: session_start(); include("Breadcrumb.php"); $trail = new Breadcrumb(); $trail->add('Careers', $_SERVER['PHP_SELF'], 1); $trail -> output(); # REMOVE SPECIAL CHARACTERS $sPattern = array('/[^a-zA-Z0-9 -]/', '/[ -]+/', '/^-|-$/'); $sReplace = array('', '-', ''); mysql_query("SET CHARACTER_SET utf8"); //$query = "SELECT * FROM careers_mst WHERE status = 1 ORDER BY dateposted DESC LIMIT 0, 4"; if(!$_GET['jobs']){ $jobsPerPage = 4; }else{ $jobsPerPage = $_GET['jobs']; } if(!$_GET['page']){ $currPage = 1; $showMoreJobs = true; }else{ $currPage = $_GET['page']; $showMoreJobs = false; } $offset = ($currPage - 1 )* $jobsPerPage; $query = "SELECT * FROM careers_mst WHERE status = 1 ORDER BY dateposted"; $process = mysql_query($query); if(@mysql_num_rows($process) > 0){ $totalRows = @mysql_num_rows($process); $query2 = "SELECT * FROM careers_mst WHERE status = 1 ORDER BY dateposted DESC LIMIT $offset, $jobsPerPage"; $process2 = mysql_query($query2); if(@mysql_num_rows($process2) > 0){ $pagNav = pageNavigator($totalRows,$jobsPerPage,$currPage,''); while($row = @mysql_fetch_array($process2)){ $id = $row[0]; $title = stripslashes($row['title']); $title1 = preg_replace($sPattern, $sReplace, $title); $description = stripslashes($row['description']); $description1 = substr($description, 0, 200); $careers_list .= ' <div class="left" style="width:340px; padding-left:10px;"> <p><span class="blue"><strong>'.$title.'</strong></span></p> '.$description1.'... <p><a href="jobs/'.$id.'/'.$title1.'" title="Learn more">[ Learn More ]</a></p> </div>'; } /*$careers_list .= ' <div class="left" style="width: 100%; margin-top:15px;"> <p><a href="more-jobs" title="More Job Opennings">MORE JOB OPENNINGS >> </a></p> <div class="divider left"></div> </div>'; */ if($showMoreJobs){ if($totalRows > $jobsPerPage){ $currPage++; } $jobNav = "<a href=careers.php?page=$currPage title='More Job Opennings'>MORE JOB OPENNINGS >> </a>"; }else{ $jobNav = "$pagNav"; } $careers_list .= "<div class='left' style='width: 100%; margin-top:15px;'> <p>$jobNav</p> <div class='divider left'></div> </div>"; } }

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• Vim: Context sensitive code completion for PHP

  - by eddy147

  Vim gives me too much options when I use code completion. In a class, and type $class- it gives me about a zillion options, so not only from the class itself but also from php, all globals ever created, in short: a mess. I only want to have the options from the class itself (or the parent subtype class it extends from), so context or scope sensitive code completion, just like Netbeans for example. How can I do that? My current configuration is this: I am using ctags, and created 1 ctags file for our (big) application in the root. This is the .ctags file I used to create the ctags file: -R -h ".php" --exclude=.svn --languages=+PHP,-JavaScript --tag-relative=yes --regex-PHP=/abstract\s+class\s+([^ ]+)/\1/c/ --regex-PHP=/interface\s+([^ ]+)/\1/c/ --regex-PHP=/(public\s+|static\s+|protected\s+|private\s+)\$([^ \t=]+)/\2/p/ --regex-PHP=/const\s+([^ \t=]+)/\1/d/ --regex-PHP=/final\s+(public\s+|static\s+|abstract\s+|protected\s+|private\s+)function\s+\&?\s*([^ (]+)/\2/f/ --PHP-kinds=+cdf --fields=+iaS This is the .vimrc file: " autocomplete funcs and identifiers for languages autocmd FileType php set omnifunc=phpcomplete#CompletePHP autocmd FileType python set omnifunc=pythoncomplete#Complete autocmd FileType javascript set omnifunc=javascriptcomplete#CompleteJS autocmd FileType html set omnifunc=htmlcomplete#CompleteTags autocmd FileType css set omnifunc=csscomplete#CompleteCSS autocmd FileType xml set omnifunc=xmlcomplete#CompleteTags autocmd FileType php set omnifunc=phpcomplete#CompletePHP autocmd FileType c set omnifunc=ccomplete#Complete " exuberant ctags " the magic is the ';' at end. it will make vim tags file search go up from current directory until it finds one. set tags=projectrootdir/tags; map <F8> :!ctags " TagList " :tag getUser => Jump to getUser method " :tn (or tnext) => go to next search result " :tp (or tprev) => to to previous search result " :ts (or tselect) => List the current tags " => Go back to last tag location " +Left click => Go to definition of a method " More info: " http://vimdoc.sourceforge.net/htmldoc/tagsrch.html (official documentation) " http://www.vim.org/tips/tip.php?tip_id=94 (a vim tip) let Tlist_Ctags_Cmd = "~/bin/ctags" let Tlist_WinWidth = 50 map <F4> :TlistToggle<cr> "see http://vim.wikia.com/wiki/Make_Vim_completion_popup_menu_work_just_like_in_an_IDE " will change the 'completeopt' option so that Vim's popup menu doesn't select the first completion item, but rather just inserts the longest common text of all matches :set completeopt=longest,menuone " will change the behavior of the <Enter> key when the popup menu is visible. In that case the Enter key will simply select the highlighted menu item, just as <C-Y> does :inoremap <expr> <CR> pumvisible() ? "\<C-y>" : "\<C-g>u\<CR>" " inoremap <expr> <C-n> pumvisible() ? '<C-n>' : \ '<C-n><C-r>=pumvisible() ? "\<lt>Down>" : ""<CR>' inoremap <expr> <M-,> pumvisible() ? '<C-n>' : \ '<C-x><C-o><C-n><C-p><C-r>=pumvisible() ? "\<lt>Down>" : ""<CR>'

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• Rails 2.3.5 and oauth-plugin

  - by pgb

  I started a rails application from scratch, using Rails 2.3.5, and installed oauth-plugin. The installation was done by running script/plugin install git://github.com/pelle/oauth-plugin.git. Now, when I try to start the server, I get the following errors: => Rails 2.3.5 application starting on http://0.0.0.0:3000 /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/activesupport-2.3.5/lib/active_support/dependencies.rb:440:in `load_missing_constant': uninitialized constant Rails::Railtie (NameError) from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/activesupport-2.3.5/lib/active_support/dependencies.rb:80:in `const_missing' from /Users/Pablo/Projects/test.oauth/vendor/plugins/oauth-plugin/lib/oauth-plugin.rb:16 from /Library/Ruby/Site/1.8/rubygems/custom_require.rb:31:in `gem_original_require' from /Library/Ruby/Site/1.8/rubygems/custom_require.rb:31:in `require' from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/activesupport-2.3.5/lib/active_support/dependencies.rb:156:in `require' from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/activesupport-2.3.5/lib/active_support/dependencies.rb:521:in `new_constants_in' from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/activesupport-2.3.5/lib/active_support/dependencies.rb:156:in `require' from /Users/Pablo/Projects/test.oauth/vendor/plugins/oauth-plugin/rails/init.rb:1:in `evaluate_init_rb' from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/rails/plugin.rb:158:in `evaluate_init_rb' from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/activesupport-2.3.5/lib/active_support/core_ext/kernel/reporting.rb:11:in `silence_warnings' from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/rails/plugin.rb:154:in `evaluate_init_rb' from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/rails/plugin.rb:48:in `load' from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/rails/plugin/loader.rb:38:in `load_plugins' from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/rails/plugin/loader.rb:37:in `each' from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/rails/plugin/loader.rb:37:in `load_plugins' from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:369:in `load_plugins' from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:165:in `process' from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:113:in `send' from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:113:in `run' from /Users/Pablo/Projects/test.oauth/config/environment.rb:9 from /Library/Ruby/Site/1.8/rubygems/custom_require.rb:31:in `gem_original_require' from /Library/Ruby/Site/1.8/rubygems/custom_require.rb:31:in `require' from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/activesupport-2.3.5/lib/active_support/dependencies.rb:156:in `require' from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/activesupport-2.3.5/lib/active_support/dependencies.rb:521:in `new_constants_in' from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/activesupport-2.3.5/lib/active_support/dependencies.rb:156:in `require' from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/commands/server.rb:84 from /Library/Ruby/Site/1.8/rubygems/custom_require.rb:31:in `gem_original_require' from /Library/Ruby/Site/1.8/rubygems/custom_require.rb:31:in `require' from script/server:3 I can't figure out why this is failing. Am I missing a dependency? What other information I can provide to others help me figure this out?

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• rails gem permissions problem (tabs on rails)

  - by aguynamedloren

  I'm having trouble running a gem, tabs on rails -v=1.3.2, in my rails 2.3.8 app. The gem is installed locally (Ubuntu 10.10) and I have config.gem "tabs_on_rails", :version="1.3.2" in environment.rb. This is the output I get when I run script/server: loren@ubuntu:~/apps/medmentum$ script/server => Booting WEBrick => Rails 2.3.8 application starting on http://0.0.0.0:3000 no such file to load -- tabs_on_rails /usr/lib/ruby/1.8/rubygems/custom_require.rb:36:in `gem_original_require' /usr/lib/ruby/1.8/rubygems/custom_require.rb:36:in `require' /var/lib/gems/1.8/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:156:in `require' /var/lib/gems/1.8/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:521:in `new_constants_in' /var/lib/gems/1.8/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:156:in `require' /var/lib/gems/1.8/gems/rails-2.3.8/lib/rails/gem_dependency.rb:215:in `load' /var/lib/gems/1.8/gems/rails-2.3.8/lib/initializer.rb:307:in `load_gems' /var/lib/gems/1.8/gems/rails-2.3.8/lib/initializer.rb:307:in `each' /var/lib/gems/1.8/gems/rails-2.3.8/lib/initializer.rb:307:in `load_gems' /var/lib/gems/1.8/gems/rails-2.3.8/lib/initializer.rb:164:in `process' /var/lib/gems/1.8/gems/rails-2.3.8/lib/initializer.rb:113:in `send' /var/lib/gems/1.8/gems/rails-2.3.8/lib/initializer.rb:113:in `run' /home/loren/apps/medmentum/config/environment.rb:11 /usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require' /usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `require' /var/lib/gems/1.8/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:156:in `require' /var/lib/gems/1.8/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:521:in `new_constants_in' /var/lib/gems/1.8/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:156:in `require' /var/lib/gems/1.8/gems/rails-2.3.8/lib/commands/server.rb:84 /usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require' /usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `require' script/server:3 /var/lib/gems/1.8/gems/rails-2.3.8/lib/rails/plugin.rb:158:in `read': Permission denied - /var/lib/gems/1.8/gems/tabs_on_rails-1.3.2/rails/init.rb (Errno::EACCES) from /var/lib/gems/1.8/gems/rails-2.3.8/lib/rails/plugin.rb:158:in `evaluate_init_rb' from /var/lib/gems/1.8/gems/activesupport-2.3.8/lib/active_support/core_ext/kernel/reporting.rb:11:in `silence_warnings' from /var/lib/gems/1.8/gems/rails-2.3.8/lib/rails/plugin.rb:154:in `evaluate_init_rb' from /var/lib/gems/1.8/gems/rails-2.3.8/lib/rails/plugin.rb:48:in `load' from /var/lib/gems/1.8/gems/rails-2.3.8/lib/rails/plugin/loader.rb:38:in `load_plugins' from /var/lib/gems/1.8/gems/rails-2.3.8/lib/rails/plugin/loader.rb:37:in `each' from /var/lib/gems/1.8/gems/rails-2.3.8/lib/rails/plugin/loader.rb:37:in `load_plugins' from /var/lib/gems/1.8/gems/rails-2.3.8/lib/initializer.rb:369:in `load_plugins' from /var/lib/gems/1.8/gems/rails-2.3.8/lib/initializer.rb:165:in `process' from /var/lib/gems/1.8/gems/rails-2.3.8/lib/initializer.rb:113:in `send' from /var/lib/gems/1.8/gems/rails-2.3.8/lib/initializer.rb:113:in `run' from /home/loren/apps/medmentum/config/environment.rb:11 from /usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require' from /usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `require' from /var/lib/gems/1.8/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:156:in `require' from /var/lib/gems/1.8/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:521:in `new_constants_in' from /var/lib/gems/1.8/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:156:in `require' from /var/lib/gems/1.8/gems/rails-2.3.8/lib/commands/server.rb:84 from /usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require' from /usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `require' from script/server:3 When I run rake gems:install, I get this: Permission denied - /var/lib/gems/1.8/gems/tabs_on_rails-1.3.2/rails/init.rb I navigated to the tabs_on_rails gem folder in the filesystem and all of the files are locked. According to the files' properties, I am not the owner and cannot change the permissions. All of my other local gems are accessible without permissions problems, so this is odd. Any help is very much appreciated!

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• Django TemplateSyntaxError only on live server (templates exist)

  - by Tom

  I'm getting a strange error that only occurs on the live server. My Django templates directory is set up like so base.html two-column-base.html portfolio index.html extranet base.html index.html The portfolio pages work correctly locally on multiple machines. They inherit from either the root base.html or two-column-base.html. However, now that I've posted them to the live box (local machines are Windows, live is Linux), I get a TemplateSyntaxError: "Caught TemplateDoesNotExist while rendering: base.html" when I try to load any portfolio pages. It seems to be a case where the extends tag won't work in that root directory (???). Even if I do a direct_to_template on two-column-base.html (which extends base.html), I get that error. The extranet pages all work perfectly, but those templates all live inside the /extranet folder and inherit from /extranet/base.html. Possible issues I've checked: file permissions on the server are fine the template directory is correct on the live box (I'm using os.path.dirname(os.path.realpath(__file__)) to make things work across machines) files exist and the /templates directories exactly match my local copy removing the {% extends %} block from the top of any broken template causes the templates to render without a problem manually starting a shell session and calling get_template on any of the files works, but trying to render it blows up with the same exception on any of the extended templates. Doing the same with base.html, it renders perfectly (base.html also renders via direct_to_template) Django 1.2, Python 2.6 on Webfaction. Apologies in advance because this is my 3rd or 4th "I'm doing something stupid" question in a row. The only x-factor I can think of is this is my first time using Mercurial instead ofsvn. Not sure how I could have messed things up via that. EDIT: One possible source of problems: local machine is Python 2.5, live is 2.6. Here's a traceback of me trying to render 'two-column-base.html', which extends 'base.html'. Both files are in the same directory, so if it can find the first, it can find the second. c is just an empty Context object. >>> render_to_string('two-column-base.html', c) Traceback (most recent call last): File "<console>", line 1, in <module> File "/home/lightfin/webapps/django/lib/python2.6/django/template/loader.py", line 186, in render_to_string return t.render(context_instance) File "/home/lightfin/webapps/django/lib/python2.6/django/template/__init__.py", line 173, in render return self._render(context) File "/home/lightfin/webapps/django/lib/python2.6/django/template/__init__.py", line 167, in _render return self.nodelist.render(context) File "/home/lightfin/webapps/django/lib/python2.6/django/template/__init__.py", line 796, in render bits.append(self.render_node(node, context)) File "/home/lightfin/webapps/django/lib/python2.6/django/template/debug.py", line 72, in render_node result = node.render(context) File "/home/lightfin/webapps/django/lib/python2.6/django/template/loader_tags.py", line 103, in render compiled_parent = self.get_parent(context) File "/home/lightfin/webapps/django/lib/python2.6/django/template/loader_tags.py", line 100, in get_parent return get_template(parent) File "/home/lightfin/webapps/django/lib/python2.6/django/template/loader.py", line 157, in get_template template, origin = find_template(template_name) File "/home/lightfin/webapps/django/lib/python2.6/django/template/loader.py", line 138, in find_template raise TemplateDoesNotExist(name) TemplateSyntaxError: Caught TemplateDoesNotExist while rendering: base.html I'm wondering if this is somehow related to the template caching that was just added to Django. EDIT 2 (per lazerscience): template-related settings: import os PROJECT_ROOT = os.path.dirname(os.path.realpath(__file__)) TEMPLATE_DIRS = ( os.path.join(PROJECT_ROOT, 'templates'), ) sample view: def project_list(request, jobs, extra_context={}): context = { 'jobs': jobs, } print context context.update(extra_context) return render_to_response('portfolio/index.html', context, context_instance=RequestContext(request)) The templates in reverse-order are: http://thosecleverkids.com/junk/index.html http://thosecleverkids.com/junk/portfolio-base.html http://thosecleverkids.com/junk/two-column-base.html http://thosecleverkids.com/junk/base.html though in the real project the first two live in a directory called "portfolio".

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• How to sanely configure security policy in Tomcat 6

  - by Chas Emerick

  I'm using Tomcat 6.0.24, as packaged for Ubuntu Karmic. The default security policy of Ubuntu's Tomcat package is pretty stringent, but appears straightforward. In /var/lib/tomcat6/conf/policy.d, there are a variety of files that establish default policy. Worth noting at the start: I've not changed the stock tomcat install at all -- no new jars into its common lib directory(ies), no server.xml changes, etc. Putting the .war file in the webapps directory is the only deployment action. the web application I'm deploying fails with thousands of access denials under this default policy (as reported to the log thanks to the -Djava.security.debug="access,stack,failure" system property). turning off the security manager entirely results in no errors whatsoever, and proper app functionality What I'd like to do is add an application-specific security policy file to the policy.d directory, which seems to be the recommended practice. I added this to policy.d/100myapp.policy (as a starting point -- I would like to eventually trim back the granted permissions to only what the app actually needs): grant codeBase "file:${catalina.base}/webapps/ROOT.war" { permission java.security.AllPermission; }; grant codeBase "file:${catalina.base}/webapps/ROOT/-" { permission java.security.AllPermission; }; grant codeBase "file:${catalina.base}/webapps/ROOT/WEB-INF/-" { permission java.security.AllPermission; }; grant codeBase "file:${catalina.base}/webapps/ROOT/WEB-INF/lib/-" { permission java.security.AllPermission; }; grant codeBase "file:${catalina.base}/webapps/ROOT/WEB-INF/classes/-" { permission java.security.AllPermission; }; Note the thrashing around attempting to find the right codeBase declaration. I think that's likely my fundamental problem. Anyway, the above (really only the first two grants appear to have any effect) almost works: the thousands of access denials are gone, and I'm left with just one. Relevant stack trace: java.security.AccessControlException: access denied (java.io.FilePermission /var/lib/tomcat6/webapps/ROOT/WEB-INF/classes/com/foo/some-file-here.txt read) java.security.AccessControlContext.checkPermission(AccessControlContext.java:323) java.security.AccessController.checkPermission(AccessController.java:546) java.lang.SecurityManager.checkPermission(SecurityManager.java:532) java.lang.SecurityManager.checkRead(SecurityManager.java:871) java.io.File.exists(File.java:731) org.apache.naming.resources.FileDirContext.file(FileDirContext.java:785) org.apache.naming.resources.FileDirContext.lookup(FileDirContext.java:206) org.apache.naming.resources.ProxyDirContext.lookup(ProxyDirContext.java:299) org.apache.catalina.loader.WebappClassLoader.findResourceInternal(WebappClassLoader.java:1937) org.apache.catalina.loader.WebappClassLoader.findResource(WebappClassLoader.java:973) org.apache.catalina.loader.WebappClassLoader.getResource(WebappClassLoader.java:1108) java.lang.ClassLoader.getResource(ClassLoader.java:973) I'm pretty convinced that the actual file that's triggering the denial is irrelevant -- it's just some properties file that we check for optional configuration parameters. What's interesting is that: it doesn't exist in this context the fact that the file doesn't exist ends up throwing a security exception, rather than java.io.File.exists() simply returning false (although I suppose that's just a matter of the semantics of the read permission). Another workaround (besides just disabling the security manager in tomcat) is to add an open-ended permission to my policy file: grant { permission java.security.AllPermission; }; I presume this is functionally equivalent to turning off the security manager. I suppose I must be getting the codeBase declaration in my grants subtly wrong, but I'm not seeing it at the moment.

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• Corrupt mercurial repository - cannot update

  - by richzilla

  Hi all, i think ive managed to corrupt one of mercurial repositories, is there anyway to recover the damage? the message i get when attempting to update the repo to my default branch is: PS C:\wco\projects\ims\code> hg up -C default abort: data/Trunk/application/models/priority_model.php.i@83dbdfb60981: no match found! when i run hg verify, i get the following report: PS C:\wco\projects\ims\code> hg verify checking changesets checking manifests crosschecking files in changesets and manifests checking files data/.buildpath.i@0: missing revlog! 0: empty or missing .buildpath .buildpath@0: daf15acb5273 in manifests not found data/.project.i@0: missing revlog! 0: empty or missing .project .project@0: e8b25997d6d1 in manifests not found Rawlings IMS/index.html@3: empty or missing copy source revlog index.html:b8b2b36a6eea Rawlings IMS/index.php@3: empty or missing copy source revlog index.php:a5f76bf232e9 Rawlings IMS/index_backup.php@3: empty or missing copy source revlog index_backup.php:a5f76bf232e9 Rawlings IMS/index_this_hold.html@3: empty or missing copy source revlog index_this_hold.html:b8b2b36a6eea Rawlings IMS/testera.php@3: empty or missing copy source revlog testera.php:6e9e3666c1bc Trunk/application/models/priority_model.php@32: 83dbdfb60981 in manifests not found data/index.html.i@0: missing revlog! 0: empty or missing index.html index.html@0: b8b2b36a6eea in manifests not found data/index.php.i@0: missing revlog! 0: empty or missing index.php index.php@0: a5f76bf232e9 in manifests not found data/index_backup.php.i@0: missing revlog! 0: empty or missing index_backup.php index_backup.php@0: a5f76bf232e9 in manifests not found data/index_this_hold.html.i@0: missing revlog! 0: empty or missing index_this_hold.html index_this_hold.html@0: b8b2b36a6eea in manifests not found data/nbproject/project.properties.i@14: missing revlog! 14: empty or missing nbproject/project.properties nbproject/project.properties@14: 1efa3074378b in manifests not found data/nbproject/project.xml.i@14: missing revlog! 14: empty or missing nbproject/project.xml nbproject/project.xml@14: 52689bf2b35a in manifests not found data/rcrawley/.buildpath.i@9: missing revlog! 9: empty or missing rcrawley/.buildpath rcrawley/.buildpath@9: 2c6411d4fcff in manifests not found data/rcrawley/.project.i@9: missing revlog! 9: empty or missing rcrawley/.project rcrawley/.project@9: cb4b1495acab in manifests not found data/rcrawley/assets/images/ajax-loader.gif.i@9: missing revlog! 9: empty or missing rcrawley/assets/images/ajax-loader.gif rcrawley/assets/images/ajax-loader.gif@9: 8ef26516c7da in manifests not found data/rcrawley/index.html.i@9: missing revlog! 9: empty or missing rcrawley/index.html rcrawley/index.html@9: 545246299dee in manifests not found data/rcrawley/index.php.i@9: missing revlog! 9: empty or missing rcrawley/index.php rcrawley/index.php@9: 66eac798ed6d in manifests not found data/rcrawley/index_backup.php.i@9: missing revlog! 9: empty or missing rcrawley/index_backup.php rcrawley/index_backup.php@9: 93971228fbf5 in manifests not found data/rcrawley/system/index.html.i@9: missing revlog! 9: empty or missing rcrawley/system/index.html rcrawley/system/index.html@9: 17360d3b566e in manifests not found data/rcrawley/testera.php.i@9: missing revlog! 9: empty or missing rcrawley/testera.php rcrawley/testera.php@9: 7d9bd5196740 in manifests not found data/testera.php.i@0: missing revlog! 0: empty or missing testera.php testera.php@0: 6e9e3666c1bc in manifests not found 1646 files, 59 changesets, 1897 total revisions 57 integrity errors encountered! (first damaged changeset appears to be 0) since the first damaged changeset is 0, this would appear to be pretty terminal. Is there anyway around this? any help would be appreciated.

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• Why so Long time span in creating Session Factory?

  - by vijay.shad

  Hi My project is web application running in the tomcat container. This application is a spring framework based hibernate application. The problem with this is it takes a lot of time when creates session factory. here is the logs 2010-04-15 23:05:28,053 DEBUG [SessionFactoryImpl] Session factory constructed with filter configurations : {} 2010-04-15 23:05:28,053 DEBUG [SessionFactoryImpl] instantiating session factory with properties: {java.vendor=Sun Microsystems Inc., sun.java.launcher=SUN_STANDARD, catalina.base=/usr/local/InstalledPrograms/apache-tomcat-6.0.20, sun.management.compiler=HotSpot Tiered Compilers, catalina.useNaming=true, os.name=Linux, sun.boot.class.path=/usr/java/jdk1.6.0_17/jre/lib/resources.jar:/usr/java/jdk1.6.0_17/jre/lib/rt.jar:/usr/java/jdk1.6.0_17/jre/lib/sunrsasign.jar:/usr/java/jdk1.6.0_17/jre/lib/jsse.jar:/usr/java/jdk1.6.0_17/jre/lib/jce.jar:/usr/java/jdk1.6.0_17/jre/lib/charsets.jar:/usr/java/jdk1.6.0_17/jre/classes, java.util.logging.config.file=/usr/local/InstalledPrograms/apache-tomcat-6.0.20/conf/logging.properties, java.vm.specification.vendor=Sun Microsystems Inc., hibernate.generate_statistics=true, java.runtime.version=1.6.0_17-b04, hibernate.cache.provider_class=org.hibernate.cache.EhCacheProvider, user.name=root, shared.loader=, tomcat.util.buf.StringCache.byte.enabled=true, hibernate.connection.release_mode=auto, user.language=en, java.naming.factory.initial=org.apache.naming.java.javaURLContextFactory, sun.boot.library.path=/usr/java/jdk1.6.0_17/jre/lib/i386, java.version=1.6.0_17, java.util.logging.manager=org.apache.juli.ClassLoaderLogManager, user.timezone=Canada/Pacific, sun.arch.data.model=32, java.endorsed.dirs=/usr/local/InstalledPrograms/apache-tomcat-6.0.20/endorsed, sun.cpu.isalist=, sun.jnu.encoding=UTF-8, file.encoding.pkg=sun.io, package.access=sun.,org.apache.catalina.,org.apache.coyote.,org.apache.tomcat.,org.apache.jasper.,sun.beans., file.separator=/, java.specification.name=Java Platform API Specification, java.class.version=50.0, user.country=US, java.home=/usr/java/jdk1.6.0_17/jre, java.vm.info=mixed mode, os.version=2.6.18-128.el5, path.separator=:, java.vm.version=14.3-b01, hibernate.jdbc.batch_size=25, java.awt.printerjob=sun.print.PSPrinterJob, sun.io.unicode.encoding=UnicodeLittle, package.definition=sun.,java.,org.apache.catalina.,org.apache.coyote.,org.apache.tomcat.,org.apache.jasper., java.naming.factory.url.pkgs=org.apache.naming, sun.rmi.dgc.client.gcInterval=3600000, user.home=/root, java.specification.vendor=Sun Microsystems Inc., java.library.path=/usr/java/jdk1.6.0_17/jre/lib/i386/server:/usr/java/jdk1.6.0_17/jre/lib/i386:/usr/java/jdk1.6.0_17/jre/../lib/i386:/usr/java/packages/lib/i386:/lib:/usr/lib, java.vendor.url=http://java.sun.com/, java.vm.vendor=Sun Microsystems Inc., hibernate.dialect=org.hibernate.dialect.MySQL5InnoDBDialect, sun.rmi.dgc.server.gcInterval=3600000, common.loader=${catalina.home}/lib,${catalina.home}/lib/*.jar, java.runtime.name=Java(TM) SE Runtime Environment, java.class.path=:/usr/local/InstalledPrograms/apache-tomcat-6.0.20/bin/bootstrap.jar, hibernate.bytecode.use_reflection_optimizer=false, java.vm.specification.name=Java Virtual Machine Specification, java.vm.specification.version=1.0, catalina.home=/usr/local/InstalledPrograms/apache-tomcat-6.0.20, sun.cpu.endian=little, sun.os.patch.level=unknown, hibernate.cache.use_query_cache=true, hibernate.connection.provider_class=org.springframework.orm.hibernate3.LocalDataSourceConnectionProvider, java.io.tmpdir=/usr/local/InstalledPrograms/apache-tomcat-6.0.20/temp, java.vendor.url.bug=http://java.sun.com/cgi-bin/bugreport.cgi, server.loader=, os.arch=i386, java.awt.graphicsenv=sun.awt.X11GraphicsEnvironment, java.ext.dirs=/usr/java/jdk1.6.0_17/jre/lib/ext:/usr/java/packages/lib/ext, user.dir=/, line.separator=, java.vm.name=Java HotSpot(TM) Server VM, hibernate.cache.use_second_level_cache=true, file.encoding=UTF-8, java.specification.version=1.6, hibernate.show_sql=true} 2010-04-15 23:08:53,516 DEBUG [AbstractEntityPersister] Static SQL for entity: com.vsd.model.Order There you can see the time delay of more than 3 mins in executing these processes. My database is mysql and database server is running on the local machine only. The container environment is Centos Linux system. I am clueless about why it takes that much of time in executing these process, But when i do the same task from under eclipse it does not take that much of time. Development environment is Windows.

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• Authlogic OpenID integration

  - by Craig

  I'm having difficulty getting OpenId authentication working with Authlogic. It appears that the problem arose with changes to the open_id_authentication plugin. From what I've read so far, one needs to switch from using gems to using plugins. Here's what I done thus far to get Authlogic-OpenID integration working: Removed relevant gems: authlogic authlogic-oid rack-openid ruby-openid * Installed, configured, and started the authlogic sample application (http://github.com/binarylogic/authlogic_example)--works as expected. This required: installing the authlogic (2.1.3) gem ($ sudo gem install authlogic) adding a dependency (config.gem "authlogic") to the environment.rb file. added migration to add open-id support to User model; ran migration; columns added as expected made changes to the UsersController and UserSessionsController to use blocks to save each. made changes to new user-sessions view to support open id (f.text_field :openid_identifier) installed open_id_authentication plugin ($ script/plugin install git://github.com/rails/open_id_authentication.git) installed the authlogic-oid plugin ($ script/plugin install git://github.com/binarylogic/authlogic_openid.git) installed the plugin ($ script/plugin install git://github.com/glebm/ruby-openid.git) restarted mongrel (CTRL-C; $ script/server) Mogrel failed to start, returning the following error: /Library/Ruby/Site/1.8/rubygems/custom_require.rb:31:in `gem_original_require': no such file to load -- rack/openid (MissingSourceFile) from /Library/Ruby/Site/1.8/rubygems/custom_require.rb:31:in `require' from /Users/craibuc/NetBeansProjects/authlogic_example/vendor/rails/activesupport/lib/active_support/dependencies.rb:156:in `require' from /Users/craibuc/NetBeansProjects/authlogic_example/vendor/rails/activesupport/lib/active_support/dependencies.rb:521:in `new_constants_in' from /Users/craibuc/NetBeansProjects/authlogic_example/vendor/rails/activesupport/lib/active_support/dependencies.rb:156:in `require' from /Users/craibuc/NetBeansProjects/authlogic_example/vendor/plugins/open_id_authentication/lib/open_id_authentication.rb:3 from /Library/Ruby/Site/1.8/rubygems/custom_require.rb:31:in `gem_original_require' from /Library/Ruby/Site/1.8/rubygems/custom_require.rb:31:in `require' from /Users/craibuc/NetBeansProjects/authlogic_example/vendor/rails/activesupport/lib/active_support/dependencies.rb:156:in `require' from /Users/craibuc/NetBeansProjects/authlogic_example/vendor/rails/activesupport/lib/active_support/dependencies.rb:521:in `new_constants_in' from /Users/craibuc/NetBeansProjects/authlogic_example/vendor/rails/activesupport/lib/active_support/dependencies.rb:156:in `require' from /Users/craibuc/NetBeansProjects/authlogic_example/vendor/plugins/open_id_authentication/init.rb:5:in `evaluate_init_rb' from ./script/../config/../vendor/rails/railties/lib/rails/plugin.rb:146:in `evaluate_init_rb' from /Users/craibuc/NetBeansProjects/authlogic_example/vendor/rails/activesupport/lib/active_support/core_ext/kernel/reporting.rb:11:in `silence_warnings' from ./script/../config/../vendor/rails/railties/lib/rails/plugin.rb:142:in `evaluate_init_rb' from ./script/../config/../vendor/rails/railties/lib/rails/plugin.rb:48:in `load' from ./script/../config/../vendor/rails/railties/lib/rails/plugin/loader.rb:38:in `load_plugins' from ./script/../config/../vendor/rails/railties/lib/rails/plugin/loader.rb:37:in `each' from ./script/../config/../vendor/rails/railties/lib/rails/plugin/loader.rb:37:in `load_plugins' from ./script/../config/../vendor/rails/railties/lib/initializer.rb:348:in `load_plugins' from ./script/../config/../vendor/rails/railties/lib/initializer.rb:163:in `process' from ./script/../config/../vendor/rails/railties/lib/initializer.rb:113:in `send' from ./script/../config/../vendor/rails/railties/lib/initializer.rb:113:in `run' from /Users/craibuc/NetBeansProjects/authlogic_example/config/environment.rb:13 from /Library/Ruby/Site/1.8/rubygems/custom_require.rb:31:in `gem_original_require' from /Library/Ruby/Site/1.8/rubygems/custom_require.rb:31:in `require' from /Users/craibuc/NetBeansProjects/authlogic_example/vendor/rails/activesupport/lib/active_support/dependencies.rb:156:in `require' from /Users/craibuc/NetBeansProjects/authlogic_example/vendor/rails/activesupport/lib/active_support/dependencies.rb:521:in `new_constants_in' from /Users/craibuc/NetBeansProjects/authlogic_example/vendor/rails/activesupport/lib/active_support/dependencies.rb:156:in `require' from /Users/craibuc/NetBeansProjects/authlogic_example/vendor/rails/railties/lib/commands/server.rb:84 from /Library/Ruby/Site/1.8/rubygems/custom_require.rb:31:in `gem_original_require' from /Library/Ruby/Site/1.8/rubygems/custom_require.rb:31:in `require' from script/server:3 I suspect this is related the rack-openid gem, but as it was dependent upon the ruby-openid gem, it was removed when the ruby-openid gem was removed. Perhaps this can be installed as a plugin. Any assistance with this matter is greatly appreciated--I'm just about to give up on OpenId integration. * ruby-openid (2.1.2) is installed at /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8. I'm not certain if this is affecting anything. In any case, I'm not sure how to uninstall it or if I should. ** edit ** It appears that there are a number of gems in the /Library/Ruby/Gems/1.8/gems directory that may be causing an issue: authlogic-oid (1.0.4) rack-openid (1.0.3) ruby-openid (2.1.7) Questions: - why doesn't the gem list command list these gems? - Why doesn't the gem uninstall command remove these gems?

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• Rendering ASP.NET MVC Views to String

  - by Rick Strahl

  It's not uncommon in my applications that I require longish text output that does not have to be rendered into the HTTP output stream. The most common scenario I have for 'template driven' non-Web text is for emails of all sorts. Logon confirmations and verifications, email confirmations for things like orders, status updates or scheduler notifications - all of which require merged text output both within and sometimes outside of Web applications. On other occasions I also need to capture the output from certain views for logging purposes. Rather than creating text output in code, it's much nicer to use the rendering mechanism that ASP.NET MVC already provides by way of it's ViewEngines - using Razor or WebForms views - to render output to a string. This is nice because it uses the same familiar rendering mechanism that I already use for my HTTP output and it also solves the problem of where to store the templates for rendering this content in nothing more than perhaps a separate view folder. The good news is that ASP.NET MVC's rendering engine is much more modular than the full ASP.NET runtime engine which was a real pain in the butt to coerce into rendering output to string. With MVC the rendering engine has been separated out from core ASP.NET runtime, so it's actually a lot easier to get View output into a string. Getting View Output from within an MVC Application If you need to generate string output from an MVC and pass some model data to it, the process to capture this output is fairly straight forward and involves only a handful of lines of code. The catch is that this particular approach requires that you have an active ControllerContext that can be passed to the view. This means that the following approach is limited to access from within Controller methods. Here's a class that wraps the process and provides both instance and static methods to handle the rendering:/// <summary> /// Class that renders MVC views to a string using the /// standard MVC View Engine to render the view. /// /// Note: This class can only be used within MVC /// applications that have an active ControllerContext. /// </summary> public class ViewRenderer { /// <summary> /// Required Controller Context /// </summary> protected ControllerContext Context { get; set; } public ViewRenderer(ControllerContext controllerContext) { Context = controllerContext; } /// <summary> /// Renders a full MVC view to a string. Will render with the full MVC /// View engine including running _ViewStart and merging into _Layout /// </summary> /// <param name="viewPath"> /// The path to the view to render. Either in same controller, shared by /// name or as fully qualified ~/ path including extension /// </param> /// <param name="model">The model to render the view with</param> /// <returns>String of the rendered view or null on error</returns> public string RenderView(string viewPath, object model) { return RenderViewToStringInternal(viewPath, model, false); } /// <summary> /// Renders a partial MVC view to string. Use this method to render /// a partial view that doesn't merge with _Layout and doesn't fire /// _ViewStart. /// </summary> /// <param name="viewPath"> /// The path to the view to render. Either in same controller, shared by /// name or as fully qualified ~/ path including extension /// </param> /// <param name="model">The model to pass to the viewRenderer</param> /// <returns>String of the rendered view or null on error</returns> public string RenderPartialView(string viewPath, object model) { return RenderViewToStringInternal(viewPath, model, true); } public static string RenderView(string viewPath, object model, ControllerContext controllerContext) { ViewRenderer renderer = new ViewRenderer(controllerContext); return renderer.RenderView(viewPath, model); } public static string RenderPartialView(string viewPath, object model, ControllerContext controllerContext) { ViewRenderer renderer = new ViewRenderer(controllerContext); return renderer.RenderPartialView(viewPath, model); } protected string RenderViewToStringInternal(string viewPath, object model, bool partial = false) { // first find the ViewEngine for this view ViewEngineResult viewEngineResult = null; if (partial) viewEngineResult = ViewEngines.Engines.FindPartialView(Context, viewPath); else viewEngineResult = ViewEngines.Engines.FindView(Context, viewPath, null); if (viewEngineResult == null) throw new FileNotFoundException(Properties.Resources.ViewCouldNotBeFound); // get the view and attach the model to view data var view = viewEngineResult.View; Context.Controller.ViewData.Model = model; string result = null; using (var sw = new StringWriter()) { var ctx = new ViewContext(Context, view, Context.Controller.ViewData, Context.Controller.TempData, sw); view.Render(ctx, sw); result = sw.ToString(); } return result; } } The key is the RenderViewToStringInternal method. The method first tries to find the view to render based on its path which can either be in the current controller's view path or the shared view path using its simple name (PasswordRecovery) or alternately by its full virtual path (~/Views/Templates/PasswordRecovery.cshtml). This code should work both for Razor and WebForms views although I've only tried it with Razor Views. Note that WebForms Views might actually be better for plain text as Razor adds all sorts of white space into its output when there are code blocks in the template. The Web Forms engine provides more accurate rendering for raw text scenarios. Once a view engine is found the view to render can be retrieved. Views in MVC render based on data that comes off the controller like the ViewData which contains the model along with the actual ViewData and ViewBag. From the View and some of the Context data a ViewContext is created which is then used to render the view with. The View picks up the Model and other data from the ViewContext internally and processes the View the same it would be processed if it were to send its output into the HTTP output stream. The difference is that we can override the ViewContext's output stream which we provide and capture into a StringWriter(). After rendering completes the result holds the output string. If an error occurs the error behavior is similar what you see with regular MVC errors - you get a full yellow screen of death including the view error information with the line of error highlighted. It's your responsibility to handle the error - or let it bubble up to your regular Controller Error filter if you have one. To use the simple class you only need a single line of code if you call the static methods. Here's an example of some Controller code that is used to send a user notification to a customer via email in one of my applications:[HttpPost] public ActionResult ContactSeller(ContactSellerViewModel model) { InitializeViewModel(model); var entryBus = new busEntry(); var entry = entryBus.LoadByDisplayId(model.EntryId); if ( string.IsNullOrEmpty(model.Email) ) entryBus.ValidationErrors.Add("Email address can't be empty.","Email"); if ( string.IsNullOrEmpty(model.Message)) entryBus.ValidationErrors.Add("Message can't be empty.","Message"); model.EntryId = entry.DisplayId; model.EntryTitle = entry.Title; if (entryBus.ValidationErrors.Count > 0) { ErrorDisplay.AddMessages(entryBus.ValidationErrors); ErrorDisplay.ShowError("Please correct the following:"); } else { string message = ViewRenderer.RenderView("~/views/template/ContactSellerEmail.cshtml",model, ControllerContext); string title = entry.Title + " (" + entry.DisplayId + ") - " + App.Configuration.ApplicationName; AppUtils.SendEmail(title, message, model.Email, entry.User.Email, false, false)) } return View(model); } Simple! The view in this case is just a plain MVC view and in this case it's a very simple plain text email message (edited for brevity here) that is created and sent off:@model ContactSellerViewModel @{ Layout = null; }re: @Model.EntryTitle @Model.ListingUrl @Model.Message ** SECURITY ADVISORY - AVOID SCAMS ** Avoid: wiring money, cross-border deals, work-at-home ** Beware: cashier checks, money orders, escrow, shipping ** More Info: @(App.Configuration.ApplicationBaseUrl)scams.html Obviously this is a very simple view (I edited out more from this page to keep it brief) -  but other template views are much more complex HTML documents or long messages that are occasionally updated and they are a perfect fit for Razor rendering. It even works with nested partial views and _layout pages. Partial Rendering Notice that I'm rendering a full View here. In the view I explicitly set the Layout=null to avoid pulling in _layout.cshtml for this view. This can also be controlled externally by calling the RenderPartial method instead: string message = ViewRenderer.RenderPartialView("~/views/template/ContactSellerEmail.cshtml",model, ControllerContext); with this line of code no layout page (or _viewstart) will be loaded, so the output generated is just what's in the view. I find myself using Partials most of the time when rendering templates, since the target of templates usually tend to be emails or other HTML fragment like output, so the RenderPartialView() method is definitely useful to me. Rendering without a ControllerContext The preceding class is great when you're need template rendering from within MVC controller actions or anywhere where you have access to the request Controller. But if you don't have a controller context handy - maybe inside a utility function that is static, a non-Web application, or an operation that runs asynchronously in ASP.NET - which makes using the above code impossible. I haven't found a way to manually create a Controller context to provide the ViewContext() what it needs from outside of the MVC infrastructure. However, there are ways to accomplish this,  but they are a bit more complex. It's possible to host the RazorEngine on your own, which side steps all of the MVC framework and HTTP and just deals with the raw rendering engine. I wrote about this process in Hosting the Razor Engine in Non-Web Applications a long while back. It's quite a process to create a custom Razor engine and runtime, but it allows for all sorts of flexibility. There's also a RazorEngine CodePlex project that does something similar. I've been meaning to check out the latter but haven't gotten around to it since I have my own code to do this. The trick to hosting the RazorEngine to have it behave properly inside of an ASP.NET application and properly cache content so templates aren't constantly rebuild and reparsed. Anyway, in the same app as above I have one scenario where no ControllerContext is available: I have a background scheduler running inside of the app that fires on timed intervals. This process could be external but because it's lightweight we decided to fire it right inside of the ASP.NET app on a separate thread. In my app the code that renders these templates does something like this:var model = new SearchNotificationViewModel() { Entries = entries, Notification = notification, User = user }; // TODO: Need logging for errors sending string razorError = null; var result = AppUtils.RenderRazorTemplate("~/views/template/SearchNotificationTemplate.cshtml", model, razorError); which references a couple of helper functions that set up my RazorFolderHostContainer class:public static string RenderRazorTemplate(string virtualPath, object model,string errorMessage = null) { var razor = AppUtils.CreateRazorHost(); var path = virtualPath.Replace("~/", "").Replace("~", "").Replace("/", "\\"); var merged = razor.RenderTemplateToString(path, model); if (merged == null) errorMessage = razor.ErrorMessage; return merged; } /// <summary> /// Creates a RazorStringHostContainer and starts it /// Call .Stop() when you're done with it. /// /// This is a static instance /// </summary> /// <param name="virtualPath"></param> /// <param name="binBasePath"></param> /// <param name="forceLoad"></param> /// <returns></returns> public static RazorFolderHostContainer CreateRazorHost(string binBasePath = null, bool forceLoad = false) { if (binBasePath == null) { if (HttpContext.Current != null) binBasePath = HttpContext.Current.Server.MapPath("~/"); else binBasePath = AppDomain.CurrentDomain.BaseDirectory; } if (_RazorHost == null || forceLoad) { if (!binBasePath.EndsWith("\\")) binBasePath += "\\"; //var razor = new RazorStringHostContainer(); var razor = new RazorFolderHostContainer(); razor.TemplatePath = binBasePath; binBasePath += "bin\\"; razor.BaseBinaryFolder = binBasePath; razor.UseAppDomain = false; razor.ReferencedAssemblies.Add(binBasePath + "ClassifiedsBusiness.dll"); razor.ReferencedAssemblies.Add(binBasePath + "ClassifiedsWeb.dll"); razor.ReferencedAssemblies.Add(binBasePath + "Westwind.Utilities.dll"); razor.ReferencedAssemblies.Add(binBasePath + "Westwind.Web.dll"); razor.ReferencedAssemblies.Add(binBasePath + "Westwind.Web.Mvc.dll"); razor.ReferencedAssemblies.Add("System.Web.dll"); razor.ReferencedNamespaces.Add("System.Web"); razor.ReferencedNamespaces.Add("ClassifiedsBusiness"); razor.ReferencedNamespaces.Add("ClassifiedsWeb"); razor.ReferencedNamespaces.Add("Westwind.Web"); razor.ReferencedNamespaces.Add("Westwind.Utilities"); _RazorHost = razor; _RazorHost.Start(); //_RazorHost.Engine.Configuration.CompileToMemory = false; } return _RazorHost; } The RazorFolderHostContainer essentially is a full runtime that mimics a folder structure like a typical Web app does including caching semantics and compiling code only if code changes on disk. It maps a folder hierarchy to views using the ~/ path syntax. The host is then configured to add assemblies and namespaces. Unfortunately the engine is not exactly like MVC's Razor - the expression expansion and code execution are the same, but some of the support methods like sections, helpers etc. are not all there so templates have to be a bit simpler. There are other folder hosts provided as well to directly execute templates from strings (using RazorStringHostContainer). The following is an example of an HTML email template @inherits RazorHosting.RazorTemplateFolderHost <ClassifiedsWeb.SearchNotificationViewModel> <html> <head> <title>Search Notifications</title> <style> body { margin: 5px;font-family: Verdana, Arial; font-size: 10pt;} h3 { color: SteelBlue; } .entry-item { border-bottom: 1px solid grey; padding: 8px; margin-bottom: 5px; } </style> </head> <body> Hello @Model.User.Name,<br /> <p>Below are your Search Results for the search phrase:</p> <h3>@Model.Notification.SearchPhrase</h3> <small>since @TimeUtils.ShortDateString(Model.Notification.LastSearch)</small> <hr /> You can see that the syntax is a little different. Instead of the familiar @model header the raw Razor  @inherits tag is used to specify the template base class (which you can extend). I took a quick look through the feature set of RazorEngine on CodePlex (now Github I guess) and the template implementation they use is closer to MVC's razor but there are other differences. In the end don't expect exact behavior like MVC templates if you use an external Razor rendering engine. This is not what I would consider an ideal solution, but it works well enough for this project. My biggest concern is the overhead of hosting a second razor engine in a Web app and the fact that here the differences in template rendering between 'real' MVC Razor views and another RazorEngine really are noticeable. You win some, you lose some It's extremely nice to see that if you have a ControllerContext handy (which probably addresses 99% of Web app scenarios) rendering a view to string using the native MVC Razor engine is pretty simple. Kudos on making that happen - as it solves a problem I see in just about every Web application I work on. But it is a bummer that a ControllerContext is required to make this simple code work. It'd be really sweet if there was a way to render views without being so closely coupled to the ASP.NET or MVC infrastructure that requires a ControllerContext. Alternately it'd be nice to have a way for an MVC based application to create a minimal ControllerContext from scratch - maybe somebody's been down that path. I tried for a few hours to come up with a way to make that work but gave up in the soup of nested contexts (MVC/Controller/View/Http). I suspect going down this path would be similar to hosting the ASP.NET runtime requiring a WorkerRequest. Brrr…. The sad part is that it seems to me that a View should really not require much 'context' of any kind to render output to string. Yes there are a few things that clearly are required like paths to the virtual and possibly the disk paths to the root of the app, but beyond that view rendering should not require much. But, no such luck. For now custom RazorHosting seems to be the only way to make Razor rendering go outside of the MVC context… Resources Full ViewRenderer.cs source code from Westwind.Web.Mvc library Hosting the Razor Engine for Non-Web Applications RazorEngine on GitHub© Rick Strahl, West Wind Technologies, 2005-2012Posted in ASP.NET   ASP.NET  MVC   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• Using jQuery and OData to Insert a Database Record

  - by Stephen Walther

  In my previous blog entry, I explored two ways of inserting a database record using jQuery. We added a new Movie to the Movie database table by using a generic handler and by using a WCF service. In this blog entry, I want to take a brief look at how you can insert a database record using OData. Introduction to OData The Open Data Protocol (OData) was developed by Microsoft to be an open standard for communicating data across the Internet. Because the protocol is compatible with standards such as REST and JSON, the protocol is particularly well suited for Ajax. OData has undergone several name changes. It was previously referred to as Astoria and ADO.NET Data Services. OData is used by Sharepoint Server 2010, Azure Storage Services, Excel 2010, SQL Server 2008, and project code name “Dallas.” Because OData is being adopted as the public interface of so many important Microsoft technologies, it is a good protocol to learn. You can learn more about OData by visiting the following websites: http://www.odata.org http://msdn.microsoft.com/en-us/data/bb931106.aspx When using the .NET framework, you can easily expose database data through the OData protocol by creating a WCF Data Service. In this blog entry, I will create a WCF Data Service that exposes the Movie database table. Create the Database and Data Model The MoviesDB database is a simple database that contains the following Movies table: You need to create a data model to represent the MoviesDB database. In this blog entry, I use the ADO.NET Entity Framework to create my data model. However, WCF Data Services and OData are not tied to any particular OR/M framework such as the ADO.NET Entity Framework. For details on creating the Entity Framework data model for the MoviesDB database, see the previous blog entry. Create a WCF Data Service You create a new WCF Service by selecting the menu option Project, Add New Item and selecting the WCF Data Service item template (see Figure 1). Name the new WCF Data Service MovieService.svc. Figure 1 – Adding a WCF Data Service Listing 1 contains the default code that you get when you create a new WCF Data Service. There are two things that you need to modify. Listing 1 – New WCF Data Service File using System; using System.Collections.Generic; using System.Data.Services; using System.Data.Services.Common; using System.Linq; using System.ServiceModel.Web; using System.Web; namespace WebApplication1 { public class MovieService : DataService< /* TODO: put your data source class name here */ > { // This method is called only once to initialize service-wide policies. public static void InitializeService(DataServiceConfiguration config) { // TODO: set rules to indicate which entity sets and service operations are visible, updatable, etc. // Examples: // config.SetEntitySetAccessRule("MyEntityset", EntitySetRights.AllRead); // config.SetServiceOperationAccessRule("MyServiceOperation", ServiceOperationRights.All); config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2; } } } First, you need to replace the comment /* TODO: put your data source class name here */ with a class that represents the data that you want to expose from the service. In our case, we need to replace the comment with a reference to the MoviesDBEntities class generated by the Entity Framework. Next, you need to configure the security for the WCF Data Service. By default, you cannot query or modify the movie data. We need to update the Entity Set Access Rule to enable us to insert a new database record. The updated MovieService.svc is contained in Listing 2: Listing 2 – MovieService.svc using System.Data.Services; using System.Data.Services.Common; namespace WebApplication1 { public class MovieService : DataService<MoviesDBEntities> { public static void InitializeService(DataServiceConfiguration config) { config.SetEntitySetAccessRule("Movies", EntitySetRights.AllWrite); config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2; } } } That’s all we have to do. We can now insert a new Movie into the Movies database table by posting a new Movie to the following URL: /MovieService.svc/Movies The request must be a POST request. The Movie must be represented as JSON. Using jQuery with OData The HTML page in Listing 3 illustrates how you can use jQuery to insert a new Movie into the Movies database table using the OData protocol. Listing 3 – Default.htm <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>jQuery OData Insert</title> <script src="http://ajax.microsoft.com/ajax/jquery/jquery-1.4.2.js" type="text/javascript"></script> <script src="Scripts/json2.js" type="text/javascript"></script> </head> <body> <form> <label>Title:</label> <input id="title" /> <br /> <label>Director:</label> <input id="director" /> </form> <button id="btnAdd">Add Movie</button> <script type="text/javascript"> $("#btnAdd").click(function () { // Convert the form into an object var data = { Title: $("#title").val(), Director: $("#director").val() }; // JSONify the data var data = JSON.stringify(data); // Post it $.ajax({ type: "POST", contentType: "application/json; charset=utf-8", url: "MovieService.svc/Movies", data: data, dataType: "json", success: insertCallback }); }); function insertCallback(result) { // unwrap result var newMovie = result["d"]; // Show primary key alert("Movie added with primary key " + newMovie.Id); } </script> </body> </html> jQuery does not include a JSON serializer. Therefore, we need to include the JSON2 library to serialize the new Movie that we wish to create. The Movie is serialized by calling the JSON.stringify() method: var data = JSON.stringify(data); You can download the JSON2 library from the following website: http://www.json.org/js.html The jQuery ajax() method is called to insert the new Movie. Notice that both the contentType and dataType are set to use JSON. The jQuery ajax() method is used to perform a POST operation against the URL MovieService.svc/Movies. Because the POST payload contains a JSON representation of a new Movie, a new Movie is added to the database table of Movies. When the POST completes successfully, the insertCallback() method is called. The new Movie is passed to this method. The method simply displays the primary key of the new Movie: Summary The OData protocol (and its enabling technology named WCF Data Services) works very nicely with Ajax. By creating a WCF Data Service, you can quickly expose your database data to an Ajax application by taking advantage of open standards such as REST, JSON, and OData. In the next blog entry, I want to take a closer look at how the OData protocol supports different methods of querying data.

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• Dynamic Types and DynamicObject References in C#

  - by Rick Strahl

  I've been working a bit with C# custom dynamic types for several customers recently and I've seen some confusion in understanding how dynamic types are referenced. This discussion specifically centers around types that implement IDynamicMetaObjectProvider or subclass from DynamicObject as opposed to arbitrary type casts of standard .NET types. IDynamicMetaObjectProvider types  are treated special when they are cast to the dynamic type. Assume for a second that I've created my own implementation of a custom dynamic type called DynamicFoo which is about as simple of a dynamic class that I can think of:public class DynamicFoo : DynamicObject { Dictionary<string, object> properties = new Dictionary<string, object>(); public string Bar { get; set; } public DateTime Entered { get; set; } public override bool TryGetMember(GetMemberBinder binder, out object result) { result = null; if (!properties.ContainsKey(binder.Name)) return false; result = properties[binder.Name]; return true; } public override bool TrySetMember(SetMemberBinder binder, object value) { properties[binder.Name] = value; return true; } } This class has an internal dictionary member and I'm exposing this dictionary member through a dynamic by implementing DynamicObject. This implementation exposes the properties dictionary so the dictionary keys can be referenced like properties (foo.NewProperty = "Cool!"). I override TryGetMember() and TrySetMember() which are fired at runtime every time you access a 'property' on a dynamic instance of this DynamicFoo type. Strong Typing and Dynamic Casting I now can instantiate and use DynamicFoo in a couple of different ways: Strong TypingDynamicFoo fooExplicit = new DynamicFoo(); var fooVar = new DynamicFoo(); These two commands are essentially identical and use strong typing. The compiler generates identical code for both of them. The var statement is merely a compiler directive to infer the type of fooVar at compile time and so the type of fooExplicit is DynamicFoo, just like fooExplicit. This is very static - nothing dynamic about it - and it completely ignores the IDynamicMetaObjectProvider implementation of my class above as it's never used. Using either of these I can access the native properties:DynamicFoo fooExplicit = new DynamicFoo();// static typing assignmentsfooVar.Bar = "Barred!"; fooExplicit.Entered = DateTime.Now; // echo back static values Console.WriteLine(fooVar.Bar); Console.WriteLine(fooExplicit.Entered); but I have no access whatsoever to the properties dictionary. Basically this creates a strongly typed instance of the type with access only to the strongly typed interface. You get no dynamic behavior at all. The IDynamicMetaObjectProvider features don't kick in until you cast the type to dynamic. If I try to access a non-existing property on fooExplicit I get a compilation error that tells me that the property doesn't exist. Again, it's clearly and utterly non-dynamic. Dynamicdynamic fooDynamic = new DynamicFoo(); fooDynamic on the other hand is created as a dynamic type and it's a completely different beast. I can also create a dynamic by simply casting any type to dynamic like this:DynamicFoo fooExplicit = new DynamicFoo(); dynamic fooDynamic = fooExplicit; Note that dynamic typically doesn't require an explicit cast as the compiler automatically performs the cast so there's no need to use as dynamic. Dynamic functionality works at runtime and allows for the dynamic wrapper to look up and call members dynamically. A dynamic type will look for members to access or call in two places: Using the strongly typed members of the object Using theIDynamicMetaObjectProvider Interface methods to access members So rather than statically linking and calling a method or retrieving a property, the dynamic type looks up - at runtime  - where the value actually comes from. It's essentially late-binding which allows runtime determination what action to take when a member is accessed at runtime *if* the member you are accessing does not exist on the object. Class members are checked first before IDynamicMetaObjectProvider interface methods are kick in. All of the following works with the dynamic type:dynamic fooDynamic = new DynamicFoo(); // dynamic typing assignments fooDynamic.NewProperty = "Something new!"; fooDynamic.LastAccess = DateTime.Now; // dynamic assigning static properties fooDynamic.Bar = "dynamic barred"; fooDynamic.Entered = DateTime.Now; // echo back dynamic values Console.WriteLine(fooDynamic.NewProperty); Console.WriteLine(fooDynamic.LastAccess); Console.WriteLine(fooDynamic.Bar); Console.WriteLine(fooDynamic.Entered); The dynamic type can access the native class properties (Bar and Entered) and create and read new ones (NewProperty,LastAccess) all using a single type instance which is pretty cool. As you can see it's pretty easy to create an extensible type this way that can dynamically add members at runtime dynamically. The Alter Ego of IDynamicObject The key point here is that all three statements - explicit, var and dynamic - declare a new DynamicFoo(), but the dynamic declaration results in completely different behavior than the first two simply because the type has been cast to dynamic. Dynamic binding means that the type loses its typical strong typing, compile time features. You can see this easily in the Visual Studio code editor. As soon as you assign a value to a dynamic you lose Intellisense and you see which means there's no Intellisense and no compiler type checking on any members you apply to this instance. If you're new to the dynamic type it might seem really confusing that a single type can behave differently depending on how it is cast, but that's exactly what happens when you use a type that implements IDynamicMetaObjectProvider. Declare the type as its strong type name and you only get to access the native instance members of the type. Declare or cast it to dynamic and you get dynamic behavior which accesses native members plus it uses IDynamicMetaObjectProvider implementation to handle any missing member definitions by running custom code. You can easily cast objects back and forth between dynamic and the original type:dynamic fooDynamic = new DynamicFoo(); fooDynamic.NewProperty = "New Property Value"; DynamicFoo foo = fooDynamic; foo.Bar = "Barred"; Here the code starts out with a dynamic cast and a dynamic assignment. The code then casts back the value to the DynamicFoo. Notice that when casting from dynamic to DynamicFoo and back we typically do not have to specify the cast explicitly - the compiler can induce the type so I don't need to specify as dynamic or as DynamicFoo. Moral of the Story This easy interchange between dynamic and the underlying type is actually super useful, because it allows you to create extensible objects that can expose non-member data stores and expose them as an object interface. You can create an object that hosts a number of strongly typed properties and then cast the object to dynamic and add additional dynamic properties to the same type at runtime. You can easily switch back and forth between the strongly typed instance to access the well-known strongly typed properties and to dynamic for the dynamic properties added at runtime. Keep in mind that dynamic object access has quite a bit of overhead and is definitely slower than strongly typed binding, so if you're accessing the strongly typed parts of your objects you definitely want to use a strongly typed reference. Reserve dynamic for the dynamic members to optimize your code. The real beauty of dynamic is that with very little effort you can build expandable objects or objects that expose different data stores to an object interface. I'll have more on this in my next post when I create a customized and extensible Expando object based on DynamicObject.© Rick Strahl, West Wind Technologies, 2005-2012Posted in CSharp  .NET   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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