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  • Sprite.js surface background

    - by user1086671
    I'm making a tile-based game using Sprite.js. It is not easy to redraw every tile each frame, so I tried to make a scrolling surface background. There is an example here http://batiste.dosimple.ch/sprite.js/tests/test_scrolling.html The example works, but it seems like ScrollingSurface.update is buggy or there is something I'm missing. What I tried to do is to draw 5x5 tiles and after 5 seconds draw another 5x5 tiles near the first ones. But it draws only the first ones. And surface.update() only updates the position of surface. Here is my code https://github.com/Sektoid/sprite.js/blob/master/tests/test_scrolling.html (You need also to set this.divider = 1.0 in scrolling.js to avoid drawing the same tiles 4 times.) There aren't any sprite.js-forums like with the other sprite- and game-engines have, so I'm asking here.

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  • Windows Azure Service Bus Splitter and Aggregator

    - by Alan Smith
    This article will cover basic implementations of the Splitter and Aggregator patterns using the Windows Azure Service Bus. The content will be included in the next release of the “Windows Azure Service Bus Developer Guide”, along with some other patterns I am working on. I’ve taken the pattern descriptions from the book “Enterprise Integration Patterns” by Gregor Hohpe. I bought a copy of the book in 2004, and recently dusted it off when I started to look at implementing the patterns on the Windows Azure Service Bus. Gregor has also presented an session in 2011 “Enterprise Integration Patterns: Past, Present and Future” which is well worth a look. I’ll be covering more patterns in the coming weeks, I’m currently working on Wire-Tap and Scatter-Gather. There will no doubt be a section on implementing these patterns in my “SOA, Connectivity and Integration using the Windows Azure Service Bus” course. There are a number of scenarios where a message needs to be divided into a number of sub messages, and also where a number of sub messages need to be combined to form one message. The splitter and aggregator patterns provide a definition of how this can be achieved. This section will focus on the implementation of basic splitter and aggregator patens using the Windows Azure Service Bus direct programming model. In BizTalk Server receive pipelines are typically used to implement the splitter patterns, with sequential convoy orchestrations often used to aggregate messages. In the current release of the Service Bus, there is no functionality in the direct programming model that implements these patterns, so it is up to the developer to implement them in the applications that send and receive messages. Splitter A message splitter takes a message and spits the message into a number of sub messages. As there are different scenarios for how a message can be split into sub messages, message splitters are implemented using different algorithms. The Enterprise Integration Patterns book describes the splatter pattern as follows: How can we process a message if it contains multiple elements, each of which may have to be processed in a different way? Use a Splitter to break out the composite message into a series of individual messages, each containing data related to one item. The Enterprise Integration Patterns website provides a description of the Splitter pattern here. In some scenarios a batch message could be split into the sub messages that are contained in the batch. The splitting of a message could be based on the message type of sub-message, or the trading partner that the sub message is to be sent to. Aggregator An aggregator takes a stream or related messages and combines them together to form one message. The Enterprise Integration Patterns book describes the aggregator pattern as follows: How do we combine the results of individual, but related messages so that they can be processed as a whole? Use a stateful filter, an Aggregator, to collect and store individual messages until a complete set of related messages has been received. Then, the Aggregator publishes a single message distilled from the individual messages. The Enterprise Integration Patterns website provides a description of the Aggregator pattern here. A common example of the need for an aggregator is in scenarios where a stream of messages needs to be combined into a daily batch to be sent to a legacy line-of-business application. The BizTalk Server EDI functionality provides support for batching messages in this way using a sequential convoy orchestration. Scenario The scenario for this implementation of the splitter and aggregator patterns is the sending and receiving of large messages using a Service Bus queue. In the current release, the Windows Azure Service Bus currently supports a maximum message size of 256 KB, with a maximum header size of 64 KB. This leaves a safe maximum body size of 192 KB. The BrokeredMessage class will support messages larger than 256 KB; in fact the Size property is of type long, implying that very large messages may be supported at some point in the future. The 256 KB size restriction is set in the service bus components that are deployed in the Windows Azure data centers. One of the ways of working around this size restriction is to split large messages into a sequence of smaller sub messages in the sending application, send them via a queue, and then reassemble them in the receiving application. This scenario will be used to demonstrate the pattern implementations. Implementation The splitter and aggregator will be used to provide functionality to send and receive large messages over the Windows Azure Service Bus. In order to make the implementations generic and reusable they will be implemented as a class library. The splitter will be implemented in the LargeMessageSender class and the aggregator in the LargeMessageReceiver class. A class diagram showing the two classes is shown below. Implementing the Splitter The splitter will take a large brokered message, and split the messages into a sequence of smaller sub-messages that can be transmitted over the service bus messaging entities. The LargeMessageSender class provides a Send method that takes a large brokered message as a parameter. The implementation of the class is shown below; console output has been added to provide details of the splitting operation. public class LargeMessageSender {     private static int SubMessageBodySize = 192 * 1024;     private QueueClient m_QueueClient;       public LargeMessageSender(QueueClient queueClient)     {         m_QueueClient = queueClient;     }       public void Send(BrokeredMessage message)     {         // Calculate the number of sub messages required.         long messageBodySize = message.Size;         int nrSubMessages = (int)(messageBodySize / SubMessageBodySize);         if (messageBodySize % SubMessageBodySize != 0)         {             nrSubMessages++;         }           // Create a unique session Id.         string sessionId = Guid.NewGuid().ToString();         Console.WriteLine("Message session Id: " + sessionId);         Console.Write("Sending {0} sub-messages", nrSubMessages);           Stream bodyStream = message.GetBody<Stream>();         for (int streamOffest = 0; streamOffest < messageBodySize;             streamOffest += SubMessageBodySize)         {                                     // Get the stream chunk from the large message             long arraySize = (messageBodySize - streamOffest) > SubMessageBodySize                 ? SubMessageBodySize : messageBodySize - streamOffest;             byte[] subMessageBytes = new byte[arraySize];             int result = bodyStream.Read(subMessageBytes, 0, (int)arraySize);             MemoryStream subMessageStream = new MemoryStream(subMessageBytes);               // Create a new message             BrokeredMessage subMessage = new BrokeredMessage(subMessageStream, true);             subMessage.SessionId = sessionId;               // Send the message             m_QueueClient.Send(subMessage);             Console.Write(".");         }         Console.WriteLine("Done!");     }} The LargeMessageSender class is initialized with a QueueClient that is created by the sending application. When the large message is sent, the number of sub messages is calculated based on the size of the body of the large message. A unique session Id is created to allow the sub messages to be sent as a message session, this session Id will be used for correlation in the aggregator. A for loop in then used to create the sequence of sub messages by creating chunks of data from the stream of the large message. The sub messages are then sent to the queue using the QueueClient. As sessions are used to correlate the messages, the queue used for message exchange must be created with the RequiresSession property set to true. Implementing the Aggregator The aggregator will receive the sub messages in the message session that was created by the splitter, and combine them to form a single, large message. The aggregator is implemented in the LargeMessageReceiver class, with a Receive method that returns a BrokeredMessage. The implementation of the class is shown below; console output has been added to provide details of the splitting operation.   public class LargeMessageReceiver {     private QueueClient m_QueueClient;       public LargeMessageReceiver(QueueClient queueClient)     {         m_QueueClient = queueClient;     }       public BrokeredMessage Receive()     {         // Create a memory stream to store the large message body.         MemoryStream largeMessageStream = new MemoryStream();           // Accept a message session from the queue.         MessageSession session = m_QueueClient.AcceptMessageSession();         Console.WriteLine("Message session Id: " + session.SessionId);         Console.Write("Receiving sub messages");           while (true)         {             // Receive a sub message             BrokeredMessage subMessage = session.Receive(TimeSpan.FromSeconds(5));               if (subMessage != null)             {                 // Copy the sub message body to the large message stream.                 Stream subMessageStream = subMessage.GetBody<Stream>();                 subMessageStream.CopyTo(largeMessageStream);                   // Mark the message as complete.                 subMessage.Complete();                 Console.Write(".");             }             else             {                 // The last message in the sequence is our completeness criteria.                 Console.WriteLine("Done!");                 break;             }         }                     // Create an aggregated message from the large message stream.         BrokeredMessage largeMessage = new BrokeredMessage(largeMessageStream, true);         return largeMessage;     } }   The LargeMessageReceiver initialized using a QueueClient that is created by the receiving application. The receive method creates a memory stream that will be used to aggregate the large message body. The AcceptMessageSession method on the QueueClient is then called, which will wait for the first message in a message session to become available on the queue. As the AcceptMessageSession can throw a timeout exception if no message is available on the queue after 60 seconds, a real-world implementation should handle this accordingly. Once the message session as accepted, the sub messages in the session are received, and their message body streams copied to the memory stream. Once all the messages have been received, the memory stream is used to create a large message, that is then returned to the receiving application. Testing the Implementation The splitter and aggregator are tested by creating a message sender and message receiver application. The payload for the large message will be one of the webcast video files from http://www.cloudcasts.net/, the file size is 9,697 KB, well over the 256 KB threshold imposed by the Service Bus. As the splitter and aggregator are implemented in a separate class library, the code used in the sender and receiver console is fairly basic. The implementation of the main method of the sending application is shown below.   static void Main(string[] args) {     // 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);       // Use the MessagingFactory to create a queue client     QueueClient queueClient = factory.CreateQueueClient(AccountDetails.QueueName);       // Open the input file.     FileStream fileStream = new FileStream(AccountDetails.TestFile, FileMode.Open);       // Create a BrokeredMessage for the file.     BrokeredMessage largeMessage = new BrokeredMessage(fileStream, true);       Console.WriteLine("Sending: " + AccountDetails.TestFile);     Console.WriteLine("Message body size: " + largeMessage.Size);     Console.WriteLine();         // Send the message with a LargeMessageSender     LargeMessageSender sender = new LargeMessageSender(queueClient);     sender.Send(largeMessage);       // Close the messaging facory.     factory.Close();  } The implementation of the main method of the receiving application is shown below. static void Main(string[] args) {       // 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);       // Use the MessagingFactory to create a queue client     QueueClient queueClient = factory.CreateQueueClient(AccountDetails.QueueName);       // Create a LargeMessageReceiver and receive the message.     LargeMessageReceiver receiver = new LargeMessageReceiver(queueClient);     BrokeredMessage largeMessage = receiver.Receive();       Console.WriteLine("Received message");     Console.WriteLine("Message body size: " + largeMessage.Size);       string testFile = AccountDetails.TestFile.Replace(@"\In\", @"\Out\");     Console.WriteLine("Saving file: " + testFile);       // Save the message body as a file.     Stream largeMessageStream = largeMessage.GetBody<Stream>();     largeMessageStream.Seek(0, SeekOrigin.Begin);     FileStream fileOut = new FileStream(testFile, FileMode.Create);     largeMessageStream.CopyTo(fileOut);     fileOut.Close();       Console.WriteLine("Done!"); } In order to test the application, the sending application is executed, which will use the LargeMessageSender class to split the message and place it on the queue. The output of the sender console is shown below. The console shows that the body size of the large message was 9,929,365 bytes, and the message was sent as a sequence of 51 sub messages. When the receiving application is executed the results are shown below. The console application shows that the aggregator has received the 51 messages from the message sequence that was creating in the sending application. The messages have been aggregated to form a massage with a body of 9,929,365 bytes, which is the same as the original large message. The message body is then saved as a file. Improvements to the Implementation The splitter and aggregator patterns in this implementation were created in order to show the usage of the patterns in a demo, which they do quite well. When implementing these patterns in a real-world scenario there are a number of improvements that could be made to the design. Copying Message Header Properties When sending a large message using these classes, it would be great if the message header properties in the message that was received were copied from the message that was sent. The sending application may well add information to the message context that will be required in the receiving application. When the sub messages are created in the splitter, the header properties in the first message could be set to the values in the original large message. The aggregator could then used the values from this first sub message to set the properties in the message header of the large message during the aggregation process. Using Asynchronous Methods The current implementation uses the synchronous send and receive methods of the QueueClient class. It would be much more performant to use the asynchronous methods, however doing so may well affect the sequence in which the sub messages are enqueued, which would require the implementation of a resequencer in the aggregator to restore the correct message sequence. Handling Exceptions In order to keep the code readable no exception handling was added to the implementations. In a real-world scenario exceptions should be handled accordingly.

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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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  • WCF Windows Service - Long operations/Callback to calling module

    - by A9S6
    I have a Windows Service that takes the name of a bunch of files and do operations on them (zip/unzip, updating db etc). The operations can take time depending on size and number of files sent to the service. (1) The module that is sending a request to this service waits until the files are processed. I want to know if there is a way to provide a callback in the service that will notify the calling module when it is finished processing the files. Please note that multiple modules can call the service at a time to process files so the service will need to provide some kind of a TaskId I guess. (2) If a service method is called and is running and another call is made to the same service, then how will that call be processed(I think there is only one thread asociated with the service). I have seen that when the service is taking time in processing a method, the threads associated with the service begin to increase.

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  • C# WCF - Failed to invoke the service.

    - by Keith Barrows
    I am getting the following error when trying to use the WCF Test Client to hit my new web service. What is weird is every once in awhile it will execute once then start popping this error. Failed to invoke the service. Possible causes: The service is offline or inaccessible; the client-side configuration does not match the proxy; the existing proxy is invalid. Refer to the stack trace for more detail. You can try to recover by starting a new proxy, restoring to default configuration, or refreshing the service. My code (interface): [ServiceContract(Namespace = "http://rivworks.com/Services/2010/04/19")] public interface ISync { [OperationContract] bool Execute(long ClientID); } My code (class): public class Sync : ISync { #region ISync Members bool ISync.Execute(long ClientID) { return model.Product(ClientID); } #endregion } My config (EDIT - posted entire serviceModel section): <system.serviceModel> <diagnostics performanceCounters="Default"> <messageLogging logMalformedMessages="true" logMessagesAtServiceLevel="true" logMessagesAtTransportLevel="true" /> </diagnostics> <serviceHostingEnvironment aspNetCompatibilityEnabled="false" /> <behaviors> <endpointBehaviors> <behavior name="JsonpServiceBehavior"> <webHttp /> </behavior> </endpointBehaviors> <serviceBehaviors> <behavior name="SimpleServiceBehavior"> <serviceMetadata httpGetEnabled="True" policyVersion="Policy15"/> </behavior> <behavior name="RivWorks.Web.Service.ServiceBehavior"> <!-- To avoid disclosing metadata information, set the value below to false and remove the metadata endpoint above before deployment --> <serviceMetadata httpGetEnabled="true"/> <!-- To receive exception details in faults for debugging purposes, set the value below to true. Set to false before deployment to avoid disclosing exception information --> <serviceDebug includeExceptionDetailInFaults="true"/> </behavior> </serviceBehaviors> </behaviors> <services> <service name="RivWorks.Web.Service.NegotiateService" behaviorConfiguration="SimpleServiceBehavior"> <endpoint address="" binding="customBinding" bindingConfiguration="jsonpBinding" behaviorConfiguration="JsonpServiceBehavior" contract="RivWorks.Web.Service.NegotiateService" /> <!--<host> <baseAddresses> <add baseAddress="http://kab.rivworks.com/services"/> </baseAddresses> </host> <endpoint address="" binding="wsHttpBinding" contract="RivWorks.Web.Service.NegotiateService" />--> <endpoint address="mex" binding="mexHttpBinding" contract="RivWorks.Web.Service.NegotiateService" /> </service> <service name="RivWorks.Web.Service.Sync" behaviorConfiguration="RivWorks.Web.Service.ServiceBehavior"> <endpoint address="" binding="wsHttpBinding" contract="RivWorks.Web.Service.ISync" /> <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" /> </service> </services> <extensions> <bindingElementExtensions> <add name="jsonpMessageEncoding" type="RivWorks.Web.Service.JSONPBindingExtension, RivWorks.Web.Service, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" /> </bindingElementExtensions> </extensions> <bindings> <customBinding> <binding name="jsonpBinding" > <jsonpMessageEncoding /> <httpTransport manualAddressing="true"/> </binding> </customBinding> </bindings> </system.serviceModel> 2 questions: What am I missing that causes this error? How can I increase the time out for the service? TIA!

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  • Background not showing behind floating divs

    - by lolalola
    Hi, what's wrong with this code? The background disappears behind the divs when I add float: left to #text and #text2. But when I remove the float: left, everything looks good. <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <style type="text/css"> #first{ width: 200px; background-color: #345752; } #left_b{ background:transparent url('img/left.png'); background-position: left top; background-repeat: repeat-y; min-height: 30px; } #right_b{ background:transparent url('img/right.png'); background-position: right top; background-repeat: repeat-y; } #text{ float: left; width: 50px; height: 30px; } #text2{ float: left; width: 70px; height: 30px; } </style> </head> <body> <div id = "first"> <div id = "left_b"> <div id = "right_b"> <div id = "text">text 1</div> <div id = "text2">text 2</div> </div> </div> </div> </body> </html>

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  • Restarting service from a client computer without rights

    - by Jason
    I have already created the program to restart a SQL database but it only works if the client has the rights. This is going to be done on a local network from a client computer when they can't get a person that has the password on the phone. Any thoughts I'm currently using the servicecontroller to start and stop database. When I don't have the rights I get a access denied error, or This operation might require other privileges. Not sure if impersonation would work since I don't have the userid and password.

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  • When is onBind or onCreate called in an android service browser plugin?

    - by anselm
    I have adapted the example plugin of the android source and the browser recognises the plugin without any problem. Here is an extract of AndroidManifest.xml: <application android:icon="@drawable/icon" android:label="@string/app_name" android:debuggable="true"> <service android:name="com.domain.plugin.PluginService"> <intent-filter> <action android:name="android.webkit.PLUGIN" /> </intent-filter> </service> </application> <uses-sdk android:minSdkVersion="7" /> <uses-permission android:name="android.webkit.permission.PLUGIN"></uses-permission> The actual Service class looks like so: public class PluginService extends Service { @Override public IBinder onBind(Intent arg0) { Log.d("PluginService", "onBind"); return null; } @Override public void onCreate() { Log.d("PluginService", "onCreate"); // TODO Auto-generated method stub super.onCreate(); AssetInstaller.getInstance(this).installAssets("/data/data/com.domain.plugin"); } } The AssetInstaller code is supposed to extract some files required by the actual plugin into the /data/data/com.domain.plugin directory, however wether onBind nor onCreate are called. But I get lot's of debug trace of the actual libnpplugin.so file I'm using. So the puzzle is when and under what circumstance is the Service bound or created in case of a browser plugin. As things look the service seems to be a dummy service. Having said that, is there another intent that can be executed at installation time probably? The only solution I see right now is installing the needed files from the native plugin code instead. Any ideas? I know this is quite a tricky question ;)

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  • grails question (sample 1 of Grails To Action book) problem with Controller and Service

    - by fegloff
    Hi, I'm doing Grails To Action sample for chapter one. Every was just fine until I started to work with Services. When I run the app I have the following error: groovy.lang.MissingPropertyException: No such property: quoteService for class: qotd.QuoteController at qotd.QuoteController$_closure3.doCall(QuoteController.groovy:14) at qotd.QuoteController$_closure3.doCall(QuoteController.groovy) at java.lang.Thread.run(Thread.java:619) Here is my groovie QuoteService class, which has an error within the definition of GetStaticQuote (ERROR: Groovy:unable to resolve class Quote) package qotd class QuoteService { boolean transactional = false def getRandomQuote() { def allQuotes = Quote.list() def randomQuote = null if (allQuotes.size() > 0) { def randomIdx = new Random().nextInt(allQuotes.size()) randomQuote = allQuotes[randomIdx] } else { randomQuote = getStaticQuote() } return randomQuote } def getStaticQuote() { return new Quote(author: "Anonymous",content: "Real Programmers Don't eat quiche") } } Controller groovie class package qotd class QuoteController { def index = { redirect(action: random) } def home = { render "<h1>Real Programmers do not each quiche!</h1>" } def random = { def randomQuote = quoteService.getRandomQuote() [ quote : randomQuote ] } def ajaxRandom = { def randomQuote = quoteService.getRandomQuote() render "<q>${randomQuote.content}</q>" + "<p>${randomQuote.author}</p>" } } Quote Class: package qotd class Quote { String content String author Date created = new Date() static constraints = { author(blank:false) content(maxSize:1000, blank:false) } } I'm doing the samples using Eclipse with grails addin. Any advice? Regards, Francisco

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  • Should Service Depend on Many Repositories, or Break Them Up?

    - by Josh Pollard
    I'm using a repository pattern for my data access. So I basically have a repository per table/class. My UI currently uses service classes to actually get things done, and these service classes wrap, and therefore depend on repositories. In many cases my services are only dependent upon one or two repositories, so things aren't too crazy. Unfortunately, one of my forms in the UI expects the user to enter data that will span five different tables. For this form I made a single service class that depends upon five repositories. Then the methods within the service for saving and loading the data call the appropriate methods on all of the corresponding repositories. As you can imagine, the save and load methods in this service are really big. Also, unit testing this service is getting really difficult because I have to setup so many fake repositories. Would it have been a better choice to break this single service apart into a few smaller services? It would put more code at the UI layer, but would make the services smaller and more testable.

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  • Android - How to decide wether to run a Service in a separate Process?

    - by pableu
    I am working on an Android application that collects sensor data over the course of multiple hours. For that, we have a Service that collects the Sensor Data (e.g. Acceleration, GPS, ..), does some processing and stores them remotely on a server. Currently, this Service runs in a separate process (using android:service=":background" in the manifest). This complicates the communication between the Activities and the Service, but my predecessors created the Application this way because they thought that separating the Service from the Activities would make it more stable. I would like some more factual reasons for the effort of running a separate process. What are the advantages? Does it really run more stable? Is the Service less likely to be killed by the OS (to free up resources) if it's in a separate process? Our Application uses startForeground() and friends to minimize the chance of getting killed by the OS. The Android docs are not very specific about this, the mostly state that it depends on the Application's purpose ;-) TL;DR What are objective reasons to put a long-running Service in a separate process (in Android)?

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  • VMWare server host agent service won't start

    - by Bimo Arioseno
    I'm using VMWare Server 2.0 on Windows Server 2003 R2. Sometimes after restarting the host machine, the VMWare host agent service won't start due to an error. This is the error messages from Event Viewer: [Service control manager] Timeout (30000 milliseconds) waiting for the VMware Host Agent service to connect. [Service control manager] The VMware Host Agent service failed to start due to the following error: The service did not respond to the start or control request in a timely fashion. I've set the service to automatically restart after subsequent failure using services.msc (using a 10 min. delay), but it still won't start. Only starting the service manually seems to work. Has anyone experienced this before? What workarounds or fixes are there?

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  • SMF restarting service whenever there's output?

    - by Phillip Oldham
    I'm trying to add a custom service to SMF's configuration, which seems successful in that the service starts and there is a log file, but therein lies the problem; the service, on start-up, prints some logging messages to the stderr. It seems that SMF is seeing those messages and, believing them to be errors, restarts the service, giving up after a number of tries and leaving the service off. What would be the best way to manage this service with SMF? The logging is needed for diagnosing problems, and would be problematic to disable. Is it possible to configure this service to only restart if the service exists?

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  • Can't change Firefox menu background color using userChrome.css on Windows 7

    - by soupagain
    I can't change Firefox's menu background color using userChrome.css on Windows 7. menubar, menubutton, menulist, menu, menuitem { color: red !important; background-color: orange !important; } This seems to work as the menubar changes to red and orange. But the background-color on the actual drop down menu stays the same (that Windows 7 menu look), although the text color does change to red. Any ideas??

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  • Is there any automatic tool to remove edges from an image that has been anti-aliased onto a white ba

    - by Macha
    I have a few images that have been anti-aliased onto a white background that I want to put on a transparent background. Just selecting it with the -wand tool/fuzzy select tool/select your terminology of choice- and deleting the background tends to leave a ring of off-white pixels around the image, or eat into the image depending on the tolerance setting. Is there some better way to do this, preferably an automatic tool? (I'm on Linux)

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  • tomcat start service NoClassDefFoundError?

    - by mobibob
    I am trying to redeploy my server on a new server with a different DNS and IP address. Therefore, I think my problem is in the configuration to find JAR files. Is there a way to get more detail as to which class is being requested so I can narrow down my problem. Does anyone have any suggested troubleshooting guidance for such problem? BTW - the configuration was working on the original server, and I tried to find all the locations in the files: conf/, worker.properties, server.xml, catalina.policy, web.xml. The jarkarta.log repeats the starting... error initializing ... forever. Very boring, therefore, the problem has to be fundamental. Apparently, the error message is recorded in the log across more than one line and would be this: Error occurred during initialization of VM java/lang/NoClassDefFoundError : java/lang/Object [2012-05-21 18:20:33] [info] Procrun (2.0.4.0) started [2012-05-21 18:20:33] [info] Running Service... [2012-05-21 18:20:33] [info] Starting service... [2012-05-21 18:20:33] [info] Error occurred during initialization of VM [2012-05-21 18:20:33] [info] java/lang/NoClassDefFoundError [2012-05-21 18:20:33] [info] : java/lang/Object [2012-05-21 18:21:59] [info] Procrun (2.0.4.0) started [2012-05-21 18:21:59] [info] Running Service... [2012-05-21 18:21:59] [info] Starting service... [2012-05-21 18:21:59] [info] Error occurred during initialization of VM [2012-05-21 18:21:59] [info] java/lang/NoClassDefFoundError [2012-05-21 18:21:59] [info] : java/lang/Object [2012-05-21 18:35:16] [info] Procrun (2.0.4.0) started [2012-05-21 18:35:16] [info] Running Service... [2012-05-21 18:35:16] [info] Starting service... [2012-05-21 18:35:16] [info] Error occurred during initialization of VM [2012-05-21 18:35:16] [info] java/lang/NoClassDefFoundError [2012-05-21 18:35:16] [info] : java/lang/Object [2012-05-21 18:45:25] [info] Procrun (2.0.4.0) started [2012-05-21 18:45:25] [info] Running Service... [2012-05-21 18:45:25] [info] Starting service... [2012-05-21 18:45:25] [info] Error occurred during initialization of VM [2012-05-21 18:45:25] [info] java/lang/NoClassDefFoundError [2012-05-21 18:45:25] [info] : java/lang/Object [2012-05-21 18:46:29] [info] Procrun (2.0.4.0) started [2012-05-21 18:46:29] [info] Running Service... [2012-05-21 18:46:29] [info] Starting service... [2012-05-21 18:46:29] [info] Error occurred during initialization of VM [2012-05-21 18:46:29] [info] java/lang/NoClassDefFoundError

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  • Save a single web page (with background images) with Wget

    - by mikael
    I want to use Wget to save single web pages (not recursively, not whole sites) for reference. Much like Firefox's "Web Page, complete". My first problem is: I can't get Wget to save background images specified in the CSS. Even if it did save the background image files I don't think --convert-links would convert the background-image URLs in the CSS file to point to the locally saved background images. Firefox has the same problem. My second problem is: If there are images on the page I want to save that are hosted on another server (like ads) these wont be included. --span-hosts doesn't seem to solve that problem with the line below. I'm using: wget --no-parent --timestamping --convert-links --page-requisites --no-directories --no-host-directories -erobots=off http://domain.tld/webpage.html

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  • Can't change Firefox menu background color using userChrome.css on Windows 7

    - by soupagain
    I can't change Firefox's menu background color using userChrome.css on Windows 7. menubar, menubutton, menulist, menu, menuitem { color: red !important; background-color: orange !important; } This seems to work as the menubar changes to red and orange. But the background-color on the actual drop down menu stays the same (that Windows 7 menu look), although the text color does change to red. Any ideas??

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