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• Flow-Design Cheat Sheet &ndash; Part I, Notation

  - by Ralf Westphal

  You want to avoid the pitfalls of object oriented design? Then this is the right place to start. Use Flow-Oriented Analysis (FOA) and –Design (FOD or just FD for Flow-Design) to understand a problem domain and design a software solution. Flow-Orientation as described here is related to Flow-Based Programming, Event-Based Programming, Business Process Modelling, and even Event-Driven Architectures. But even though “thinking in flows” is not new, I found it helpful to deviate from those precursors for several reasons. Some aim at too big systems for the average programmer, some are concerned with only asynchronous processing, some are even not very much concerned with programming at all. What I was looking for was a design method to help in software projects of any size, be they large or tiny, involing synchronous or asynchronous processing, being local or distributed, running on the web or on the desktop or on a smartphone. That´s why I took ideas from all of the above sources and some additional and came up with Event-Based Components which later got repositioned and renamed to Flow-Design. In the meantime this has generated some discussion (in the German developer community) and several teams have started to work with Flow-Design. Also I´ve conducted quite some trainings using Flow-Orientation for design. The results are very promising. Developers find it much easier to design software using Flow-Orientation than OOAD-based object orientation. Since Flow-Orientation is moving fast and is not covered completely by a single source like a book, demand has increased for at least an overview of the current state of its notation. This page is trying to answer this demand by briefly introducing/describing every notational element as well as their translation into C# source code. Take this as a cheat sheet to put next to your whiteboard when designing software. However, please do not expect any explanation as to the reasons behind Flow-Design elements. Details on why Flow-Design at all and why in this specific way you´ll find in the literature covering the topic. Here´s a resource page on Flow-Design/Event-Based Components, if you´re able to read German. Notation Connected Functional Units The basic element of any FOD are functional units (FU): Think of FUs as some kind of software code block processing data. For the moment forget about classes, methods, “components”, assemblies or whatever. See a FU as an abstract piece of code. Software then consists of just collaborating FUs. I´m using circles/ellipses to draw FUs. But if you like, use rectangles. Whatever suites your whiteboard needs best.   The purpose of FUs is to process input and produce output. FUs are transformational. However, FUs are not called and do not call other FUs. There is no dependency between FUs. Data just flows into a FU (input) and out of it (output). From where and where to is of no concern to a FU.   This way FUs can be concatenated in arbitrary ways:   Each FU can accept input from many sources and produce output for many sinks:   Flows Connected FUs form a flow with a start and an end. Data is entering a flow at a source, and it´s leaving it through a sink. Think of sources and sinks as special FUs which conntect wires to the environment of a network of FUs.   Wiring Details Data is flowing into/out of FUs through wires. This is to allude to electrical engineering which since long has been working with composable parts. Wires are attached to FUs usings pins. They are the entry/exit points for the data flowing along the wires. Input-/output pins currently need not be drawn explicitly. This is to keep designing on a whiteboard simple and quick.   Data flowing is of some type, so wires have a type attached to them. And pins have names. If there is only one input pin and output pin on a FU, though, you don´t need to mention them. The default is Process for a single input pin, and Result for a single output pin. But you´re free to give even single pins different names.   There is a shortcut in use to address a certain pin on a destination FU:   The type of the wire is put in parantheses for two reasons. 1. This way a “no-type” wire can be easily denoted, 2. this is a natural way to describe tuples of data.   To describe how much data is flowing, a star can be put next to the wire type:   Nesting – Boards and Parts If more than 5 to 10 FUs need to be put in a flow a FD starts to become hard to understand. To keep diagrams clutter free they can be nested. You can turn any FU into a flow: This leads to Flow-Designs with different levels of abstraction. A in the above illustration is a high level functional unit, A.1 and A.2 are lower level functional units. One of the purposes of Flow-Design is to be able to describe systems on different levels of abstraction and thus make it easier to understand them. Humans use abstraction/decomposition to get a grip on complexity. Flow-Design strives to support this and make levels of abstraction first class citizens for programming. You can read the above illustration like this: Functional units A.1 and A.2 detail what A is supposed to do. The whole of A´s responsibility is decomposed into smaller responsibilities A.1 and A.2. FU A thus does not do anything itself anymore! All A is responsible for is actually accomplished by the collaboration between A.1 and A.2. Since A now is not doing anything anymore except containing A.1 and A.2 functional units are devided into two categories: boards and parts. Boards are just containing other functional units; their sole responsibility is to wire them up. A is a board. Boards thus depend on the functional units nested within them. This dependency is not of a functional nature, though. Boards are not dependent on services provided by nested functional units. They are just concerned with their interface to be able to plug them together. Parts are the workhorses of flows. They contain the real domain logic. They actually transform input into output. However, they do not depend on other functional units. Please note the usage of source and sink in boards. They correspond to input-pins and output-pins of the board.   Implicit Dependencies Nesting functional units leads to a dependency tree. Boards depend on nested functional units, they are the inner nodes of the tree. Parts are independent, they are the leafs: Even though dependencies are the bane of software development, Flow-Design does not usually draw these dependencies. They are implicitly created by visually nesting functional units. And they are harmless. Boards are so simple in their functionality, they are little affected by changes in functional units they are depending on. But functional units are implicitly dependent on more than nested functional units. They are also dependent on the data types of the wires attached to them: This is also natural and thus does not need to be made explicit. And it pertains mainly to parts being dependent. Since boards don´t do anything with regard to a problem domain, they don´t care much about data types. Their infrastructural purpose just needs types of input/output-pins to match.   Explicit Dependencies You could say, Flow-Orientation is about tackling complexity at its root cause: that´s dependencies. “Natural” dependencies are depicted naturally, i.e. implicitly. And whereever possible dependencies are not even created. Functional units don´t know their collaborators within a flow. This is core to Flow-Orientation. That makes for high composability of functional units. A part is as independent of other functional units as a motor is from the rest of the car. And a board is as dependend on nested functional units as a motor is on a spark plug or a crank shaft. With Flow-Design software development moves closer to how hardware is constructed. Implicit dependencies are not enough, though. Sometimes explicit dependencies make designs easier – as counterintuitive this might sound. So FD notation needs a ways to denote explicit dependencies: Data flows along wires. But data does not flow along dependency relations. Instead dependency relations represent service calls. Functional unit C is depending on/calling services on functional unit S. If you want to be more specific, name the services next to the dependency relation: Although you should try to stay clear of explicit dependencies, they are fundamentally ok. See them as a way to add another dimension to a flow. Usually the functionality of the independent FU (“Customer repository” above) is orthogonal to the domain of the flow it is referenced by. If you like emphasize this by using different shapes for dependent and independent FUs like above. Such dependencies can be used to link in resources like databases or shared in-memory state. FUs can not only produce output but also can have side effects. A common pattern for using such explizit dependencies is to hook a GUI into a flow as the source and/or the sink of data: Which can be shortened to: Treat FUs others depend on as boards (with a special non-FD API the dependent part is connected to), but do not embed them in a flow in the diagram they are depended upon.   Attributes of Functional Units Creation and usage of functional units can be modified with attributes. So far the following have shown to be helpful: Singleton: FUs are by default multitons. FUs in the same of different flows with the same name refer to the same functionality, but to different instances. Think of functional units as objects that get instanciated anew whereever they appear in a design. Sometimes though it´s helpful to reuse the same instance of a functional unit; this is always due to valuable state it holds. Signify this by annotating the FU with a “(S)”. Multiton: FUs on which others depend are singletons by default. This is, because they usually are introduced where shared state comes into play. If you want to change them to be a singletons mark them with a “(M)”. Configurable: Some parts need to be configured before the can do they work in a flow. Annotate them with a “(C)” to have them initialized before any data items to be processed by them arrive. Do not assume any order in which FUs are configured. How such configuration is happening is an implementation detail. Entry point: In each design there needs to be a single part where “it all starts”. That´s the entry point for all processing. It´s like Program.Main() in C# programs. Mark the entry point part with an “(E)”. Quite often this will be the GUI part. How the entry point is started is an implementation detail. Just consider it the first FU to start do its job.   Patterns / Standard Parts If more than a single wire is attached to an output-pin that´s called a split (or fork). The same data is flowing on all of the wires. Remember: Flow-Designs are synchronous by default. So a split does not mean data is processed in parallel afterwards. Processing still happens synchronously and thus one branch after another. Do not assume any specific order of the processing on the different branches after the split.   It is common to do a split and let only parts of the original data flow on through the branches. This effectively means a map is needed after a split. This map can be implicit or explicit.   Although FUs can have multiple input-pins it is preferrable in most cases to combine input data from different branches using an explicit join: The default output of a join is a tuple of its input values. The default behavior of a join is to output a value whenever a new input is received. However, to produce its first output a join needs an input for all its input-pins. Other join behaviors can be: reset all inputs after an output only produce output if data arrives on certain input-pins

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• Windows Azure Service Bus Scatter-Gather Implementation

  - by Alan Smith

  One of the more challenging enterprise integration patterns that developers may wish to implement is the Scatter-Gather pattern. In this article I will show the basic implementation of a scatter-gather pattern using the topic-subscription model of the windows azure service bus. I’ll be using the implementation in demos, and also as a lab in my training courses, and the pattern will also be included in the next release of my free e-book the “Windows Azure Service Bus Developer Guide”. The Scatter-Gather pattern answers the following scenario. How do you maintain the overall message flow when a message needs to be sent to multiple recipients, each of which may send a reply? Use a Scatter-Gather that broadcasts a message to multiple recipients and re-aggregates the responses back into a single message. The Enterprise Integration Patterns website provides a description of the Scatter-Gather pattern here.   The scatter-gather pattern uses a composite of the publish-subscribe channel pattern and the aggregator pattern. The publish-subscribe channel is used to broadcast messages to a number of receivers, and the aggregator is used to gather the response messages and aggregate them together to form a single message. Scatter-Gather Scenario The scenario for this scatter-gather implementation is an application that allows users to answer questions in a poll based voting scenario. A poll manager application will be used to broadcast questions to users, the users will use a voting application that will receive and display the questions and send the votes back to the poll manager. The poll manager application will receive the users’ votes and aggregate them together to display the results. The scenario should be able to scale to support a large number of users.   Scatter-Gather Implementation The diagram below shows the overall architecture for the scatter-gather implementation.       Messaging Entities Looking at the scatter-gather pattern diagram it can be seen that the topic-subscription architecture is well suited for broadcasting a message to a number of subscribers. The poll manager application can send the question messages to a topic, and each voting application can receive the question message on its own subscription. The static limit of 2,000 subscriptions per topic in the current release means that 2,000 voting applications can receive question messages and take part in voting. The vote messages can then be sent to the poll manager application using a queue. The voting applications will send their vote messages to the queue, and the poll manager will receive and process the vote messages. The questions topic and answer queue are created using the Windows Azure Developer Portal. Each instance of the voting application will create its own subscription in the questions topic when it starts, allowing the question messages to be broadcast to all subscribing voting applications. Data Contracts Two simple data contracts will be used to serialize the questions and votes as brokered messages. The code for these is shown below.   [DataContract] public class Question {     [DataMember]     public string QuestionText { get; set; } }     To keep the implementation of the voting functionality simple and focus on the pattern implementation, the users can only vote yes or no to the questions.   [DataContract] public class Vote {     [DataMember]     public string QuestionText { get; set; }       [DataMember]     public bool IsYes { get; set; } }     Poll Manager Application The poll manager application has been implemented as a simple WPF application; the user interface is shown below. A question can be entered in the text box, and sent to the topic by clicking the Add button. The topic and subscriptions used for broadcasting the messages are shown in a TreeView control. The questions that have been broadcast and the resulting votes are shown in a ListView control. When the application is started any existing subscriptions are cleared form the topic, clients are then created for the questions topic and votes queue, along with background workers for receiving and processing the vote messages, and updating the display of subscriptions.   public MainWindow() {     InitializeComponent();       // Create a new results list and data bind it.     Results = new ObservableCollection<Result>();     lsvResults.ItemsSource = Results;       // Create a token provider with the relevant credentials.     TokenProvider credentials =         TokenProvider.CreateSharedSecretTokenProvider         (AccountDetails.Name, AccountDetails.Key);       // Create a URI for the serivce bus.     Uri serviceBusUri = ServiceBusEnvironment.CreateServiceUri         ("sb", AccountDetails.Namespace, string.Empty);       // Clear out any old subscriptions.     NamespaceManager = new NamespaceManager(serviceBusUri, credentials);     IEnumerable<SubscriptionDescription> subs =         NamespaceManager.GetSubscriptions(AccountDetails.ScatterGatherTopic);     foreach (SubscriptionDescription sub in subs)     {         NamespaceManager.DeleteSubscription(sub.TopicPath, sub.Name);     }       // Create the MessagingFactory     MessagingFactory factory = MessagingFactory.Create(serviceBusUri, credentials);       // Create the topic and queue clients.     ScatterGatherTopicClient =         factory.CreateTopicClient(AccountDetails.ScatterGatherTopic);     ScatterGatherQueueClient =         factory.CreateQueueClient(AccountDetails.ScatterGatherQueue);       // Start the background worker threads.     VotesBackgroundWorker = new BackgroundWorker();     VotesBackgroundWorker.DoWork += new DoWorkEventHandler(ReceiveMessages);     VotesBackgroundWorker.RunWorkerAsync();       SubscriptionsBackgroundWorker = new BackgroundWorker();     SubscriptionsBackgroundWorker.DoWork += new DoWorkEventHandler(UpdateSubscriptions);     SubscriptionsBackgroundWorker.RunWorkerAsync(); }     When the poll manager user nters a question in the text box and clicks the Add button a question message is created and sent to the topic. This message will be broadcast to all the subscribing voting applications. An instance of the Result class is also created to keep track of the votes cast, this is then added to an observable collection named Results, which is data-bound to the ListView control.   private void btnAddQuestion_Click(object sender, RoutedEventArgs e) {     // Create a new result for recording votes.     Result result = new Result()     {         Question = txtQuestion.Text     };     Results.Add(result);       // Send the question to the topic     Question question = new Question()     {         QuestionText = result.Question     };     BrokeredMessage msg = new BrokeredMessage(question);     ScatterGatherTopicClient.Send(msg);       txtQuestion.Text = ""; }     The Results class is implemented as follows.   public class Result : INotifyPropertyChanged {     public string Question { get; set; }       private int m_YesVotes;     private int m_NoVotes;       public event PropertyChangedEventHandler PropertyChanged;       public int YesVotes     {         get { return m_YesVotes; }         set         {             m_YesVotes = value;             NotifyPropertyChanged("YesVotes");         }     }       public int NoVotes     {         get { return m_NoVotes; }         set         {             m_NoVotes = value;             NotifyPropertyChanged("NoVotes");         }     }       private void NotifyPropertyChanged(string prop)     {         if(PropertyChanged != null)         {             PropertyChanged(this, new PropertyChangedEventArgs(prop));         }     } }     The INotifyPropertyChanged interface is implemented so that changes to the number of yes and no votes will be updated in the ListView control. Receiving the vote messages from the voting applications is done asynchronously, using a background worker thread.   // This runs on a background worker. private void ReceiveMessages(object sender, DoWorkEventArgs e) {     while (true)     {         // Receive a vote message from the queue         BrokeredMessage msg = ScatterGatherQueueClient.Receive();         if (msg != null)         {             // Deserialize the message.             Vote vote = msg.GetBody<Vote>();               // Update the results.             foreach (Result result in Results)             {                 if (result.Question.Equals(vote.QuestionText))                 {                     if (vote.IsYes)                     {                         result.YesVotes++;                     }                     else                     {                         result.NoVotes++;                     }                     break;                 }             }               // Mark the message as complete.             msg.Complete();         }       } }     When a vote message is received, the result that matches the vote question is updated with the vote from the user. The message is then marked as complete. A second background thread is used to update the display of subscriptions in the TreeView, with a dispatcher used to update the user interface. // This runs on a background worker. private void UpdateSubscriptions(object sender, DoWorkEventArgs e) {     while (true)     {         // Get a list of subscriptions.         IEnumerable<SubscriptionDescription> subscriptions =             NamespaceManager.GetSubscriptions(AccountDetails.ScatterGatherTopic);           // Update the user interface.         SimpleDelegate setQuestion = delegate()         {             trvSubscriptions.Items.Clear();             TreeViewItem topicItem = new TreeViewItem()             {                 Header = AccountDetails.ScatterGatherTopic             };               foreach (SubscriptionDescription subscription in subscriptions)             {                 TreeViewItem subscriptionItem = new TreeViewItem()                 {                     Header = subscription.Name                 };                 topicItem.Items.Add(subscriptionItem);             }             trvSubscriptions.Items.Add(topicItem);               topicItem.ExpandSubtree();         };         this.Dispatcher.BeginInvoke(DispatcherPriority.Send, setQuestion);           Thread.Sleep(3000);     } }       Voting Application The voting application is implemented as another WPF application. This one is more basic, and allows the user to vote “Yes” or “No” for the questions sent by the poll manager application. The user interface for that application is shown below. When an instance of the voting application is created it will create a subscription in the questions topic using a GUID as the subscription name. The application can then receive copies of every question message that is sent to the topic. Clients for the new subscription and the votes queue are created, along with a background worker to receive the question messages. The voting application is set to receiving mode, meaning it is ready to receive a question message from the subscription.   public MainWindow() {     InitializeComponent();       // Set the mode to receiving.     IsReceiving = true;       // Create a token provider with the relevant credentials.     TokenProvider credentials =         TokenProvider.CreateSharedSecretTokenProvider         (AccountDetails.Name, AccountDetails.Key);       // Create a URI for the serivce bus.     Uri serviceBusUri = ServiceBusEnvironment.CreateServiceUri         ("sb", AccountDetails.Namespace, string.Empty);       // Create the MessagingFactory     MessagingFactory factory = MessagingFactory.Create(serviceBusUri, credentials);       // Create a subcription for this instance     NamespaceManager mgr = new NamespaceManager(serviceBusUri, credentials);     string subscriptionName = Guid.NewGuid().ToString();     mgr.CreateSubscription(AccountDetails.ScatterGatherTopic, subscriptionName);       // Create the subscription and queue clients.     ScatterGatherSubscriptionClient = factory.CreateSubscriptionClient         (AccountDetails.ScatterGatherTopic, subscriptionName);     ScatterGatherQueueClient =         factory.CreateQueueClient(AccountDetails.ScatterGatherQueue);       // Start the background worker thread.     BackgroundWorker = new BackgroundWorker();     BackgroundWorker.DoWork += new DoWorkEventHandler(ReceiveMessages);     BackgroundWorker.RunWorkerAsync(); }     I took the inspiration for creating the subscriptions in the voting application from the chat application that uses topics and subscriptions blogged by Ovais Akhter here. The method that receives the question messages runs on a background thread. If the application is in receive mode, a question message will be received from the subscription, the question will be displayed in the user interface, the voting buttons enabled, and IsReceiving set to false to prevent more questing from being received before the current one is answered.   // This runs on a background worker. private void ReceiveMessages(object sender, DoWorkEventArgs e) {     while (true)     {         if (IsReceiving)         {             // Receive a question message from the topic.             BrokeredMessage msg = ScatterGatherSubscriptionClient.Receive();             if (msg != null)             {                 // Deserialize the message.                 Question question = msg.GetBody<Question>();                   // Update the user interface.                 SimpleDelegate setQuestion = delegate()                 {                     lblQuestion.Content = question.QuestionText;                     btnYes.IsEnabled = true;                     btnNo.IsEnabled = true;                 };                 this.Dispatcher.BeginInvoke(DispatcherPriority.Send, setQuestion);                 IsReceiving = false;                   // Mark the message as complete.                 msg.Complete();             }         }         else         {             Thread.Sleep(1000);         }     } }     When the user clicks on the Yes or No button, the btnVote_Click method is called. This will create a new Vote data contract with the appropriate question and answer and send the message to the poll manager application using the votes queue. The user voting buttons are then disabled, the question text cleared, and the IsReceiving flag set to true to allow a new message to be received.   private void btnVote_Click(object sender, RoutedEventArgs e) {     // Create a new vote.     Vote vote = new Vote()     {         QuestionText = (string)lblQuestion.Content,         IsYes = ((sender as Button).Content as string).Equals("Yes")     };       // Send the vote message.     BrokeredMessage msg = new BrokeredMessage(vote);     ScatterGatherQueueClient.Send(msg);       // Update the user interface.     lblQuestion.Content = "";     btnYes.IsEnabled = false;     btnNo.IsEnabled = false;     IsReceiving = true; }     Testing the Application In order to test the application, an instance of the poll manager application is started; the user interface is shown below. As no instances of the voting application have been created there are no subscriptions present in the topic. When an instance of the voting application is created the subscription will be displayed in the poll manager. Now that a voting application is subscribing, a questing can be sent from the poll manager application. When the message is sent to the topic, the voting application will receive the message and display the question. The voter can then answer the question by clicking on the appropriate button. The results of the vote are updated in the poll manager application. When two more instances of the voting application are created, the poll manager will display the new subscriptions. More questions can then be broadcast to the voting applications. As the question messages are queued up in the subscription for each voting application, the users can answer the questions in their own time. The vote messages will be received by the poll manager application and aggregated to display the results. The screenshots of the applications part way through voting are shown below. The messages for each voting application are queued up in sequence on the voting application subscriptions, allowing the questions to be answered at different speeds by the voters.

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• Loosely coupled .NET Cache Provider using Dependency Injection

  - by Rhames

  I have recently been reading the excellent book “Dependency Injection in .NET”, written by Mark Seemann. I do not generally buy software development related books, as I never seem to have the time to read them, but I have found the time to read Mark’s book, and it was time well spent I think. Reading the ideas around Dependency Injection made me realise that the Cache Provider code I wrote about earlier (see http://geekswithblogs.net/Rhames/archive/2011/01/10/using-the-asp.net-cache-to-cache-data-in-a-model.aspx) could be refactored to use Dependency Injection, which should produce cleaner code. The goals are to: Separate the cache provider implementation (using the ASP.NET data cache) from the consumers (loose coupling). This will also mean that the dependency on System.Web for the cache provider does not ripple down into the layers where it is being consumed (such as the domain layer). Provide a decorator pattern to allow a consumer of the cache provider to be implemented separately from the base consumer (i.e. if we have a base repository, we can decorate this with a caching version). Although I used the term repository, in reality the cache consumer could be just about anything. Use constructor injection to provide the Dependency Injection, with a suitable DI container (I use Castle Windsor). The sample code for this post is available on github, https://github.com/RobinHames/CacheProvider.git ICacheProvider In the sample code, the key interface is ICacheProvider, which is in the domain layer. 1: using System; 2: using System.Collections.Generic; 3:   4: namespace CacheDiSample.Domain 5: { 6: public interface ICacheProvider<T> 7: { 8: T Fetch(string key, Func<T> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry); 9: IEnumerable<T> Fetch(string key, Func<IEnumerable<T>> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry); 10: } 11: }   This interface contains two methods to retrieve data from the cache, either as a single instance or as an IEnumerable. the second paramerter is of type Func<T>. This is the method used to retrieve data if nothing is found in the cache. The ASP.NET implementation of the ICacheProvider interface needs to live in a project that has a reference to system.web, typically this will be the root UI project, or it could be a separate project. The key thing is that the domain or data access layers do not need system.web references adding to them. In my sample MVC application, the CacheProvider is implemented in the UI project, in a folder called “CacheProviders”: 1: using System; 2: using System.Collections.Generic; 3: using System.Linq; 4: using System.Web; 5: using System.Web.Caching; 6: using CacheDiSample.Domain; 7:   8: namespace CacheDiSample.CacheProvider 9: { 10: public class CacheProvider<T> : ICacheProvider<T> 11: { 12: public T Fetch(string key, Func<T> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry) 13: { 14: return FetchAndCache<T>(key, retrieveData, absoluteExpiry, relativeExpiry); 15: } 16:   17: public IEnumerable<T> Fetch(string key, Func<IEnumerable<T>> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry) 18: { 19: return FetchAndCache<IEnumerable<T>>(key, retrieveData, absoluteExpiry, relativeExpiry); 20: } 21:   22: #region Helper Methods 23:   24: private U FetchAndCache<U>(string key, Func<U> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry) 25: { 26: U value; 27: if (!TryGetValue<U>(key, out value)) 28: { 29: value = retrieveData(); 30: if (!absoluteExpiry.HasValue) 31: absoluteExpiry = Cache.NoAbsoluteExpiration; 32:   33: if (!relativeExpiry.HasValue) 34: relativeExpiry = Cache.NoSlidingExpiration; 35:   36: HttpContext.Current.Cache.Insert(key, value, null, absoluteExpiry.Value, relativeExpiry.Value); 37: } 38: return value; 39: } 40:   41: private bool TryGetValue<U>(string key, out U value) 42: { 43: object cachedValue = HttpContext.Current.Cache.Get(key); 44: if (cachedValue == null) 45: { 46: value = default(U); 47: return false; 48: } 49: else 50: { 51: try 52: { 53: value = (U)cachedValue; 54: return true; 55: } 56: catch 57: { 58: value = default(U); 59: return false; 60: } 61: } 62: } 63:   64: #endregion 65:   66: } 67: }   The FetchAndCache helper method checks if the specified cache key exists, if it does not, the Func<U> retrieveData method is called, and the results are added to the cache. Using Castle Windsor to register the cache provider In the MVC UI project (my application root), Castle Windsor is used to register the CacheProvider implementation, using a Windsor Installer: 1: using Castle.MicroKernel.Registration; 2: using Castle.MicroKernel.SubSystems.Configuration; 3: using Castle.Windsor; 4:   5: using CacheDiSample.Domain; 6: using CacheDiSample.CacheProvider; 7:   8: namespace CacheDiSample.WindsorInstallers 9: { 10: public class CacheInstaller : IWindsorInstaller 11: { 12: public void Install(IWindsorContainer container, IConfigurationStore store) 13: { 14: container.Register( 15: Component.For(typeof(ICacheProvider<>)) 16: .ImplementedBy(typeof(CacheProvider<>)) 17: .LifestyleTransient()); 18: } 19: } 20: }   Note that the cache provider is registered as a open generic type. Consuming a Repository I have an existing couple of repository interfaces defined in my domain layer: IRepository.cs 1: using System; 2: using System.Collections.Generic; 3:   4: using CacheDiSample.Domain.Model; 5:   6: namespace CacheDiSample.Domain.Repositories 7: { 8: public interface IRepository<T> 9: where T : EntityBase 10: { 11: T GetById(int id); 12: IList<T> GetAll(); 13: } 14: }   IBlogRepository.cs 1: using System; 2: using CacheDiSample.Domain.Model; 3:   4: namespace CacheDiSample.Domain.Repositories 5: { 6: public interface IBlogRepository : IRepository<Blog> 7: { 8: Blog GetByName(string name); 9: } 10: }   These two repositories are implemented in the DataAccess layer, using Entity Framework to retrieve data (this is not important though). One important point is that in the BaseRepository implementation of IRepository, the methods are virtual. This will allow the decorator to override them. The BlogRepository is registered in a RepositoriesInstaller, again in the MVC UI project. 1: using Castle.MicroKernel.Registration; 2: using Castle.MicroKernel.SubSystems.Configuration; 3: using Castle.Windsor; 4:   5: using CacheDiSample.Domain.CacheDecorators; 6: using CacheDiSample.Domain.Repositories; 7: using CacheDiSample.DataAccess; 8:   9: namespace CacheDiSample.WindsorInstallers 10: { 11: public class RepositoriesInstaller : IWindsorInstaller 12: { 13: public void Install(IWindsorContainer container, IConfigurationStore store) 14: { 15: container.Register(Component.For<IBlogRepository>() 16: .ImplementedBy<BlogRepository>() 17: .LifestyleTransient() 18: .DependsOn(new 19: { 20: nameOrConnectionString = "BloggingContext" 21: })); 22: } 23: } 24: }   Now I can inject a dependency on the IBlogRepository into a consumer, such as a controller in my sample code: 1: using System; 2: using System.Collections.Generic; 3: using System.Linq; 4: using System.Web; 5: using System.Web.Mvc; 6:   7: using CacheDiSample.Domain.Repositories; 8: using CacheDiSample.Domain.Model; 9:   10: namespace CacheDiSample.Controllers 11: { 12: public class HomeController : Controller 13: { 14: private readonly IBlogRepository blogRepository; 15:   16: public HomeController(IBlogRepository blogRepository) 17: { 18: if (blogRepository == null) 19: throw new ArgumentNullException("blogRepository"); 20:   21: this.blogRepository = blogRepository; 22: } 23:   24: public ActionResult Index() 25: { 26: ViewBag.Message = "Welcome to ASP.NET MVC!"; 27:   28: var blogs = blogRepository.GetAll(); 29:   30: return View(new Models.HomeModel { Blogs = blogs }); 31: } 32:   33: public ActionResult About() 34: { 35: return View(); 36: } 37: } 38: }   Consuming the Cache Provider via a Decorator I used a Decorator pattern to consume the cache provider, this means my repositories follow the open/closed principle, as they do not require any modifications to implement the caching. It also means that my controllers do not have any knowledge of the caching taking place, as the DI container will simply inject the decorator instead of the root implementation of the repository. The first step is to implement a BlogRepository decorator, with the caching logic in it. Note that this can reside in the domain layer, as it does not require any knowledge of the data access methods. BlogRepositoryWithCaching.cs 1: using System; 2: using System.Collections.Generic; 3: using System.Linq; 4: using System.Text; 5:   6: using CacheDiSample.Domain.Model; 7: using CacheDiSample.Domain; 8: using CacheDiSample.Domain.Repositories; 9:   10: namespace CacheDiSample.Domain.CacheDecorators 11: { 12: public class BlogRepositoryWithCaching : IBlogRepository 13: { 14: // The generic cache provider, injected by DI 15: private ICacheProvider<Blog> cacheProvider; 16: // The decorated blog repository, injected by DI 17: private IBlogRepository parentBlogRepository; 18:   19: public BlogRepositoryWithCaching(IBlogRepository parentBlogRepository, ICacheProvider<Blog> cacheProvider) 20: { 21: if (parentBlogRepository == null) 22: throw new ArgumentNullException("parentBlogRepository"); 23:   24: this.parentBlogRepository = parentBlogRepository; 25:   26: if (cacheProvider == null) 27: throw new ArgumentNullException("cacheProvider"); 28:   29: this.cacheProvider = cacheProvider; 30: } 31:   32: public Blog GetByName(string name) 33: { 34: string key = string.Format("CacheDiSample.DataAccess.GetByName.{0}", name); 35: // hard code 5 minute expiry! 36: TimeSpan relativeCacheExpiry = new TimeSpan(0, 5, 0); 37: return cacheProvider.Fetch(key, () => 38: { 39: return parentBlogRepository.GetByName(name); 40: }, 41: null, relativeCacheExpiry); 42: } 43:   44: public Blog GetById(int id) 45: { 46: string key = string.Format("CacheDiSample.DataAccess.GetById.{0}", id); 47:   48: // hard code 5 minute expiry! 49: TimeSpan relativeCacheExpiry = new TimeSpan(0, 5, 0); 50: return cacheProvider.Fetch(key, () => 51: { 52: return parentBlogRepository.GetById(id); 53: }, 54: null, relativeCacheExpiry); 55: } 56:   57: public IList<Blog> GetAll() 58: { 59: string key = string.Format("CacheDiSample.DataAccess.GetAll"); 60:   61: // hard code 5 minute expiry! 62: TimeSpan relativeCacheExpiry = new TimeSpan(0, 5, 0); 63: return cacheProvider.Fetch(key, () => 64: { 65: return parentBlogRepository.GetAll(); 66: }, 67: null, relativeCacheExpiry) 68: .ToList(); 69: } 70: } 71: }   The key things in this caching repository are: I inject into the repository the ICacheProvider<Blog> implementation, via the constructor. This will make the cache provider functionality available to the repository. I inject the parent IBlogRepository implementation (which has the actual data access code), via the constructor. This will allow the methods implemented in the parent to be called if nothing is found in the cache. I override each of the methods implemented in the repository, including those implemented in the generic BaseRepository. Each override of these methods follows the same pattern. It makes a call to the CacheProvider.Fetch method, and passes in the parentBlogRepository implementation of the method as the retrieval method, to be used if nothing is present in the cache. Configuring the Caching Repository in the DI Container The final piece of the jigsaw is to tell Castle Windsor to use the BlogRepositoryWithCaching implementation of IBlogRepository, but to inject the actual Data Access implementation into this decorator. This is easily achieved by modifying the RepositoriesInstaller to use Windsor’s implicit decorator wiring: 1: using Castle.MicroKernel.Registration; 2: using Castle.MicroKernel.SubSystems.Configuration; 3: using Castle.Windsor; 4:   5: using CacheDiSample.Domain.CacheDecorators; 6: using CacheDiSample.Domain.Repositories; 7: using CacheDiSample.DataAccess; 8:   9: namespace CacheDiSample.WindsorInstallers 10: { 11: public class RepositoriesInstaller : IWindsorInstaller 12: { 13: public void Install(IWindsorContainer container, IConfigurationStore store) 14: { 15:   16: // Use Castle Windsor implicit wiring for the block repository decorator 17: // Register the outermost decorator first 18: container.Register(Component.For<IBlogRepository>() 19: .ImplementedBy<BlogRepositoryWithCaching>() 20: .LifestyleTransient()); 21: // Next register the IBlogRepository inmplementation to inject into the outer decorator 22: container.Register(Component.For<IBlogRepository>() 23: .ImplementedBy<BlogRepository>() 24: .LifestyleTransient() 25: .DependsOn(new 26: { 27: nameOrConnectionString = "BloggingContext" 28: })); 29: } 30: } 31: }   This is all that is needed. Now if the consumer of the repository makes a call to the repositories method, it will be routed via the caching mechanism. You can test this by stepping through the code, and seeing that the DataAccess.BlogRepository code is only called if there is no data in the cache, or this has expired. The next step is to add the SQL Cache Dependency support into this pattern, this will be a future post.

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• WPF FlowDocument - Absolute Character Position

  - by Alan Spark

  I have a WPF RichTextBox that I am typing some text into and then parsing the whole of the text to do processing on. During this parse, I have the absolute character positions of the start and end of each word. I would like to use these character positions to apply formatting to certain words. However, I have discovered that the FlowDocument uses TextPointer instances to mark positions in the document. I have found that I can create a TextRange by constructing it with start and end pointers. Once I have the TextRange I can easily apply formatting to the text within it. I have been using GetPositionAtOffset to get a TextPointer for my character offset but suspect that its offset is different from mine because the selected text is in a slightly different position from what I expect. My question is, how can I accurately convert an absolute character position to a TextPointer?

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• Workspace.PendEdit not checking out files

  - by MasterMax1313

  I'm using the TFS 2010 SDK to programmatically check in edits to files into TFS 2010. The documentation on the TFS 2010 SDK is sparse at best. When I call the method workspace.pendedit() passing in an array of files I want to mark as having a pending edit, nothing is actually checked out. So when I call workspace.checkin() passing in workspace.getpendingchanges and some comments I get an exception that there must be at least one thing that has a pending change (which should be what I passed into pendedit). Any thoughts on why the app isn't marking the files as having a pending edit in the workspace?

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• ASP.NET NVC - Add XHTML into validation error messages

  - by Neil

  Hi, Just starting with ASP.Net MVC and have hit a bit of a snag regarding validation messages. I've a custom validation attribute assigned to my class validate several properties on my model. When this validation fails, we'd like the error message to contain XHTML mark-up, including a link to help page, (this was done in the original WebForms project as a ASP:Panel). At the moment the XHTML tags such as "< a ", in the ErrorMessage are being rendered to the screen. Is there any way to get the ValidationSummary to render the XHTML markup correctly? Or is there a better way to handle this kind of validation? Thanks

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• ASP.NET MVC Areas Application Using Multiple Projects

  - by harrisonmeister

  Hi I have been following this tutorial: http://msdn.microsoft.com/en-us/library/ee307987(VS.100).aspx#registering_routes_in_account_and_store_areas and have an application (a bit more complex) like this set up. All the areas are working fine, however I have noticed that if I change the project name of the Accounts project to say Areas.Accounts, that it wont find any of my views within the accounts project due to the Area name not being the same as the project name e.g. the accounts routes.cs file still has this: public override string AreaName { get { return "Accounts"; } } Does anyone know why I would have to change it to this: public override string AreaName { // Needs to match the project name? get { return "Areas.Accounts"; } } for my views in the accounts project to work? I would really like the AreaName to still be Accounts, but for ASP.net MVC to look in the "Views\Areas\Areas.Accounts\" folder when its all munged into one project, rather than trying to find it within "View\Areas\Accounts\" Thanks Mark

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• asp.net MVC RC1 RenderPartial ViewDataDictionary

  - by Mark79

  I'm trying to pass a ViewData object from a master page to a view user control using the ViewDataDictionary. The problem is the ViewDataDictionary is not returning any values in the view user control whichever way i try it. The sample code below is using an anonymous object just for demonstration although neither this method or passing a ViewData object works. Following is the RenderPartial helper method i'm trying to use: <% Html.RenderPartial("/Views/Project/Projects.ascx", ViewData.Eval("Projects"), new ViewDataDictionary(new { Test = "Mark" })); %> and in my view user control i do the following: <%= Html.Encode(ViewData["Test"]) %> Why does this not return anything? Thanks for your help. EDIT: I'm able to pass and access the stronlgy typed model without any problems. it's the ViewDataDictionary which i'm trying to use to pass say just a single value outside of the model..

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• Removing offline/defunct files in SQL server 2008

  - by philox

  How to remove traces of files marked as OFFLINE or DEFUNCT in Microsoft SQL server 2008? I have been playing around with a setup where I create a database with 3 file-groups which are: Primary, FileGroupData and FileGroupIndex. The clustered index is using FileGroupData and a non-clustered index is set to use FileGroupIndex. To simulate a disk failure I've shut down SQL server and manually deleted the files in index file-group. To start the database I'll mark the files 'OFFLINE', but after that I can't delete the index files, which are now offline. I don't have backup of the files as they are merely indices, but that has the implication that I can't restore the files and have their status as "ONLINE". How would you recommend removing the files and the file-group as they still show up in management studio under files/file-groups. Management studio is not able to delete them. As far as I can tell this is different from the question posted in : http://stackoverflow.com/questions/462637/how-do-i-remove-offline-files-from-a-sql-server-2005-database /Philip

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• Problem making system calls with PHP scripts

  - by mazin k.

  I have the following PHP script: <?php $fortune = `fortune`; echo $fortune; ?> but the output is simply blank (no visible errors thrown). However, if I run php -a, it works: php > echo `fortune`; Be careful of reading health books, you might die of a misprint. -- Mark Twain php > Am I missing a config directive or something that would cause this? Edit: So, I tried running my script using $ php-cgi fortunetest.php and it worked as expected. Maybe the issue is with Apache2?

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• BIRT vs Jasper Reports

  - by Sandeep Jindal

  Hi, I goggled for 2 hours to find what shall I use. I found that both are good and have good community. BIRT is supported by IBM, IBM integrated Tivoli reports with it. This proves it is good and will keep growing. Jasper Reports has fairly bid community and (probably) a better report designed (iReport). My requirement is simple: I want to use quick, good reporting tool. My reporting requirements may keep on increasing, thus would like a tool which remains upto-the-mark with market. Please suggest.

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• Good book for THINKING in terms of algorithms?

  - by chrisgoyal

  Before you mark this is a duplicate, let me explain why this is different. Most of the books on algorithms are more of a reference. You basically have a list of algorithms at your disposal. But what happens when you need to create a new algorithm for something? These books don't teach how to think in terms of algorithms. So I'm looking for books that will teach me the thinking-process of creating algorithms. Any good suggestions?

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• Changing how a telerik radgrid marks a row as "modified"

  - by Scott Vercuski

  I am working with the Telerik Winforms Radgrid version 2009.2.9.701 in visual studio 2008 (C#) and I've come across and issue I can't seem to find a solution for. When the radgrid is populated and the user changes a cell within a row, the row is not flagged as "modified" until the user actually clicks onto another location on the datagrid. If the user modifies any values in a row and immediately clicks the "Save" button on my winform, the row is not flagged as having been modified and is not showing up in my list of modified rows. I am using the following code to gather the modified rows ... DataTable modifiedRows = dataTable.GetChanges(DataRowState.Modified); My question is as follows: Is there a way to mark a row as "Modified" when the user changes a value in ANY cell in the row, without the user having to click off of the row before clicking the save button. I can't seem to find the flag that marks a data row as "Modified". Thank you for your help, it is much appreciated.

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• XML/XSD intellisense not working in Visual Studio 2010

  - by Jason

  I am working on xml and xsd files in VS 2010 but intellisense isn't working. Intellisense is working for the same files in VS 2008, however. When I type '<xs:' options like "attribute", "complexType", "simpleType", or "element" do not appear. Is there some difference between the VS 2008 and VS 2010 that I'm missing? I add an xsd file to my solution. All the proper namespaces are generated automatically as such: <?xml version="1.0" encoding="utf-8"?> <xs:schema id="XMLSchema2" targetNamespace="http://tempuri.org/XMLSchema2.xsd" elementFormDefault="qualified" xmlns="http://tempuri.org/XMLSchema2.xsd" xmlns:mstns="http://tempuri.org/XMLSchema2.xsd" xmlns:xs="http://www.w3.org/2001/XMLSchema"> </xs:schema> The "xsdschema.xsd" is in the "C:\Program Files\Microsoft Visual Studio 10.0\xml\Schemas" directory. There is a check mark in the "Use" column in the XML Schemas dialog box.

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• PHP preg_replace oddity with £ pound sign and ã

  - by Barry Ramsay

  Hello I am applying the following function <?php function replaceChar($string){ $new_string = preg_replace("/[^a-zA-Z0-9\sçéèêëñòóôõöàáâäåìíîïùúûüýÿ]/", "", $string); return $new_string; } $string = "This is some text and numbers 12345 and symbols !£%^#&$ and foreign letters éèêëñòóôõöàáâäåìíîïùúûüýÿ"; echo replaceChar($string); ?> which works fine but if I add ã to the preg_replace like $new_string = preg_replace("/[^a-zA-Z0-9\sçéèêëñòóôõöàáâãäåìíîïùúûüýÿ]/", "", $string); $string = "This is some text and numbers 12345 and symbols !£%^#&$ and foreign letters éèêëñòóôõöàáâäåìíîïùúûüýÿã"; It conflicts with the pound sign £ and replaces the pound sign with the unidentified question mark in black square. This is not critical but does anyone know why this is? Thank you, Barry

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• Rails, searchlogic choose categories with checkboxes

  - by atmorell

  Hello, I am useing searchlogic to search some paintings. Each painting belong to a single category. What I would like to do is add multiple checkboxes to my search form, so that users can mark multiple categories. (joined with or) Is this possible with searchlogic? The query I am looking for is something like this: SELECT * FROM paintings WHERE category LIKE "white" OR category LIKE "red"... f.check_box :category (white) f.check_box :category (black) f.check_box :category (red) f.check_box :category (green) etc.

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• Open Financial Exchange (OFX) Banking API

  - by Gabriel Susai

  Hi, First of all I apologize if this question is asked before. I am planning to develop a small application which displays my bank account details(like Mint.com) where I can customize the display of my own. I want to know how and where to start. Where these OFX API's are available? Are they free or we need to pay and get access to those API? What is data format ( xml, xml/atom, json) ? Any article or document to understand this requirement and start developing? Any open source software where I can download the code and customize it? FYI : I am working on C#.Net. Any help would be appreciated. Edit : Mark : Thanks for you info. If I want to develop a application like Mint.com what are the other companies provide API's other than Yoodlee? Also any idea on the pricing? Thanks Gabriel Susai

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• Ajaxing a link in a table

  - by Colin Desmond

  I have a table of results in an ASP.Net MVC page where the last column is an View Details link. I want to have the user click the View Details link and an AJAX method be called to open the results in floating dialog. What I am struggling with is how to link the AJAX call to the link in the results table. I was using a link which embedded the ~/ControllerName/ViewDetails/InstanceId link directly in it. Clicking it took the user to a new page and it is this behaviour I want to replace with an AJAX call and a dialog window. Now I want to attach a jQuery handler to the link to trigger the AJAX call and I can't see how to do this other than write an jQuery handler for each row in the results table. There must be a way to mark the link as an ViewDetails link (using a class?) and attach the jQuery click handler to all instances of type class ViewDetails.

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• PHP Filter, how to filter input array

  - by esryl

  I am using PHP filter to perfom basic sanitization and validation of form data. The principle problem I am having is that I mark my form up so that all the data is in one array for the POST input. e.g. form fields, page[name], page[slug], page[body], page[status], etc. Using the following: filter_input(INPUT_POST, 'page[name]', FILTER_SANITIZE_STRING); OR filter_input(INPUT_POST, "page['name']", FILTER_SANITIZE_STRING); I am unable to access the variable. Can someone please tell me the correct name to use to access array data using filter_input()

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• SOLVED mwfeedparser integrating in my app gives EXC_BAD_ACCESS (code=1, address=0xa0040008)

  - by Pranoy C

  SOLVED- Got it! The problem was that since I am creating the DoParsingStuff *parseThisUrl object in the viewDidLoad method, it's scope was only within that method. So after the method finished, the object got deallocated. I changed it to an instance variable instead and now it works. It gives a different error but that it an entirely different issue. Issue was: I have been struggling with trying to integrate the mwfeedparser library in my app for parsing RSS and ATOM feeds. It throws a gives EXC_BAD_ACCESS error which I can't seem to troubleshoot. //My Class looks like - My interface looks like: #import <Foundation/Foundation.h> #import "MWFeedParser.h" #import "NSString+HTML.h" @protocol ParseCompleted <NSObject> -(void)parsedArray:(NSMutableArray *)parsedArray; @end @interface DoParsingStuff : NSObject<MWFeedParserDelegate> @property (nonatomic,strong) NSMutableArray *parsedItems; @property (nonatomic, strong) NSArray *itemsToDisplay; @property (nonatomic,strong) MWFeedParser *feedParser; @property (nonatomic,strong) NSURL *feedurl; @property (nonatomic,strong) id <ParseCompleted> delegate; -(id)initWithFeedURL:(NSURL *)url; @end //And Implementaion: #import "DoParsingStuff.h" @implementation DoParsingStuff @synthesize parsedItems = _parsedItems; @synthesize itemsToDisplay = _itemsToDisplay; @synthesize feedParser = _feedParser; @synthesize feedurl=_feedurl; @synthesize delegate = _delegate; -(id)initWithFeedURL:(NSURL *)url{ if(self = [super init]){ _feedurl=url; _feedParser = [[MWFeedParser alloc] initWithFeedURL:_feedurl]; _feedParser.delegate=self; _feedParser.feedParseType=ParseTypeFull; _feedParser.connectionType=ConnectionTypeAsynchronously; } return self; } -(void)doParsing{ BOOL y = [_feedParser parse]; } # pragma mark - # pragma mark MWFeedParserDelegate - (void)feedParserDidStart:(MWFeedParser *)parser { //Just tells what url is being parsed e.g. http://www.wired.com/reviews/feeds/latestProductsRss NSLog(@"Started Parsing: %@", parser.url); } - (void)feedParser:(MWFeedParser *)parser didParseFeedInfo:(MWFeedInfo *)info { //What is the Feed about e.g. "Product Reviews" NSLog(@"Parsed Feed Info: “%@”", info.title); //self.title = info.title; } - (void)feedParser:(MWFeedParser *)parser didParseFeedItem:(MWFeedItem *)item { //Prints current element's title e.g. “An Arthropod for Your iDevices” NSLog(@"Parsed Feed Item: “%@”", item.title); if (item) [_parsedItems addObject:item]; } - (void)feedParserDidFinish:(MWFeedParser *)parser {//This is where you can do your own stuff with the parsed items NSLog(@"Finished Parsing%@", (parser.stopped ? @" (Stopped)" : @"")); [_delegate parsedArray:_parsedItems]; //[self updateTableWithParsedItems]; } - (void)feedParser:(MWFeedParser *)parser didFailWithError:(NSError *)error { NSLog(@"Finished Parsing With Error: %@", error); if (_parsedItems.count == 0) { //self.title = @"Failed"; // Show failed message in title } else { // Failed but some items parsed, so show and inform of error UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Parsing Incomplete" message:@"There was an error during the parsing of this feed. Not all of the feed items could parsed." delegate:nil cancelButtonTitle:@"Dismiss" otherButtonTitles:nil]; [alert show]; } //[self updateTableWithParsedItems]; } @end //I am calling this from my main viewcontroller as such: #import "DoParsingStuff.h" @interface ViewController : UIViewController <ParseCompleted> .... //And I have the following methods in my implementation: DoParsingStuff *parseThisUrl = [[DoParsingStuff alloc] initWithFeedURL:[NSURL URLWithString:@"http://www.theverge.com/rss/index.xml"]]; parseThisUrl.delegate=self; [parseThisUrl doParsing]; I have the method defined here as- -(void)parsedArray:(NSMutableArray *)parsedArray{ NSLog(@"%@",parsedArray); } //I stepped through breakpoints- When I try to go through the breakpoints, I see that everything goes fine till the very last [parseThisUrl doParsing]; in my delegate class. After that it starts showing me memory registers where I get lost. I think it could be due to arc as I have disabled arc on the mwfeedparser files but am using arc in the above classes. If you need the entire project for this, let me know. I tried it with NSZombies enabled and got a bit more info out of it: -[DoParsingStuff respondsToSelector:]: message sent to deallocated instance 0x6a52480 I am not using release/autorelease/retain etc. in this class...but it is being used in the mwfeedparser library.

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• jquery opacity with another image

  - by user1828505

  i am trying to attatin the opacity of my image with book mark and cross image on it how to attain it i am providing my screenshot below docs.google.com/file/d/0B3IBJKENGE7RS1lwZzhYbTNRbkk/edit?pli=1 here is my js code jsfiddle.net/mwPeb/18 $(document).ready(function(){ $(".specialHoverOne").hover(function(){ // alert("i am here"); $(".ctaSpecialOne").css("visibility","visible"); }, function(){ $(".ctaSpecialOne").css("visibility","hidden"); } ); $(".ctaSpecialOne").click(function(e){ e.preventDefault(); $(this).parent().prev().prev().css({'opacity':.5}); $(this).remove(); }); });

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• Flex: Dynamically create a preview image for a video....

  - by onekidney

  I'm using the VideoDisplay to play flv's, mov's, and mp4's and everything is working great. They are all being loaded via progressive download and are not being streamed. What I'd like to do is to grab a single specified frame (like whatever is being shown at the 10 second mark), convert it to a bitmap and use that bitmap as the preview image for the video. I'd like to do this at runtime so I don't have to create a preview image for every video that would be shown. Any idea's on how to do this? I'd rather not fake it by playing it - seeking for that specific frame and then pausing it but I may have no other choice?

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• International keyboard and UITextField secure option

  - by Chonch

  Hey, I have a UITextField in a .xib file with the secure option marked as YES. I have several international keyboards on my device. When the secure option is set to NO, I have no problem using all of the international keyboards on my device, but when it is set to YES, I am only able to use the English keyboard. Is there a way to an option I can use to enable this feature, or would I have to do this manually (don't mark the secure option and replace the text the user enters with *'s)? Thanks,

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• pchart pie chart legend and graph not correlating

  - by madphp

  Hi, I have ten values in the dataset, numbers 1 - 10 and corresponding values. Some of the values are coming back as zero, so they are not added to the chart, BUT, the legend is still listing 1 - 10. Because theres values missing in the chart, the colour coding is knocked off. ie Item 1, has a value of zero, its passed over in the chart, the colour in the legend is red, Item 2, has a value of 4, the percentage is calculated, and the chart gives it the colour red which is the colour for item 1 in the legend. Hope that makes sense. How can I print the legend just for the values that are displayed in the chart? --Mark

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• RegEx match open tags except XHTML self-contained tags

  - by Jeff

  I need to match all of these opening tags: <p> <a href="foo"> But not these: <br /> <hr class="foo" /> I came up with this and wanted to make sure I've got it right. I am only capturing the a-z. <([a-z]+) *[^/]*?> I believe it says: Find a less-than, then Find (and capture) a-z one or more times, then Find zero or more spaces, then Find any character zero or more times, greedy, except /, then Find a greater-than Do I have that right? And more importantly, what do you think? =) EDIT: Hmm, which answer to mark as correct? For the record, ALL the answers are appreciated. Many thanks!

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