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• Web services or shared database for (game) server communication?

  - by jaaronfarr

  We have 2 server clusters: the first is made up of typical web applications backed by SQL databases. The second are highly optimized multiplayer game servers which keep all data in memory. Both clusters communicate with clients via HTTP (Ajax with JSON). There are a few cases in which we need to share data between the two server types, for example, reporting back and storing the results of a game (should ultimately end up in the database). We're considering several approaches for inter-server communication: Just share the MySQL databases between clusters (introduce SQL to the game servers) Sharing data in a distributed key-value store like Memcache, Redis, etc. Use an RPC technology like Google ProtoBufs or Apache Thrift Using RESTful web services (the game server would POST back to the web servers, for example) At the moment, we're leaning towards web services or just sharing the database. Sharing the database seems easy, but we're concerned this adds extra memory and a new dependency into the game servers. Web services provide good separation of concerns and fit with the existing Ajax we use, but add complexity, overhead and many more ways for communication to fail. Are there any other good reasons not to use one or the other approach? Which would be easier to scale?

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• Fastest reliable way for Clojure (Java) and Ruby apps to communicate

  - by jkndrkn

  Hi There, We have cloud-hosted (RackSpace cloud) Ruby and Java apps that will interact as follows: Ruby app sends a request to Java app. Request consists of map structure containing strings, integers, other maps, and lists (analogous to JSON). Java app analyzes data and sends reply to Ruby App. We are interested in evaluating both messaging formats (JSON, Buffer Protocols, Thrift, etc.) as well as message transmission channels/techniques (sockets, message queues, RPC, REST, SOAP, etc.) Our criteria: Short round-trip time. Low round-trip-time standard deviation. (We understand that garbage collection pauses and network usage spikes can affect this value). High availability. Scalability (we may want to have multiple instances of Ruby and Java app exchanging point-to-point messages in the future). Ease of debugging and profiling. Good documentation and community support. Bonus points for Clojure support. What combination of message format and transmission method would you recommend? Why? I've gathered here some materials we have already collected for review: Comparison of various java serialization options Comparison of Thrift and Protocol Buffers (old) Comparison of various data interchange formats Comparison of Thrift and Protocol Buffers Fallacies of Protocol Buffers RPC features Discussion of RPC in the context of AMQP (Message-Queueing) Comparison of RPC and message-passing in distributed systems (pdf) Criticism of RPC from perspective of message-passing fan Overview of Avro from Ruby programmer perspective

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• In maven2, how do I assemble bits and pieces of different modules to create final distributions?

  - by Carcassi

  I have four maven project: client api jar web service war ui jar web interface war The service war will need to be packaged to include the client api jar, together with javadocs (so that each version is distributed with a matching client and documentation). The web interface war will need the ui jar and all the dependencies (webstart/applet deployment). So I need a 5th project that does all the packaging. How to do this with ant or a script is perfectly clear to me, but not in maven. I tried the following: having the javadocs included as part of the war packaging: this requires the execution of the javadocs goal in project 1 before execution of package in project 2. Haven't found a way to bind plugins/goals across different projects. Using the assembly plugin in project2 had the same problem. create a fifth project and use the assembly plugin. Still the same problems as before, with the problem that since I need different pieces from each sub-project I do not understand how this can be done using the assembly. Is this too hard to do in maven, and should I just give up? Or I am looking at it wrong, in which case, how should I be looking at it? Thanks! Upon further reflection, here is a partial answer: Each project should build all its artifacts. This is done by having the plugins configured to run as per the prepare-resources and package phases. So, in my case, I prepare all that needs to be generated (jar, javadocs, xsd documentation, ...) as different artifacts so that a single "package" goal execution creates all. So, it's not "how project 2 forces project 1 to run different goals", but it's "make project 1 create all of its artifact as part as the normal lifecycle). This seems to simplify things.

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• when to use Hibernate vs. Simple ResultSets for small application

  - by luke

  I just started working on upgrading a small component in a distributed java application. The main application is a rather complicated applet/servlet combo running on JBoss and it extensively uses Hibernate for its DataAccess. The component i am working on however is very a very straightforward data importing service. Basically the workflow is Listen for a network event Parse the data packet, extract a set of identifiers Map the identifier set to a primary key in our database Parse the rest of the packet and insert items in a related table using the foreign key found in step 3 Repeat in the previous version of this component it used a hibernate based DAL, that is no longer usable for a variety of reasons (in particular it is EOL), so I am in charge of replacing the Data Access layer for this component. So on the one hand I think i should use Hibernate because that's what the rest of the application does, but on the other i think i should just use regular java.sql.* classes because my requirements are really straightforward and aren't expected to change any time soon. So my question is (and i understand it is subjective) at what point do you think that the added complexity of using an ORM tool (in terms of configuration, dependencies...) is worth it? UPDATE due to the way the DataAccesLayer for the main application was written (weird dependencies) i cannot easily use it, i would have to implement it myself.

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• Behavior of Struts2 and convention-plugin when there is Index(extends ActionSupport)

  - by hanishi

  We have an Action class named 'Index' immediately under com.example.common.action and is annotated @ParentPackage('default') which is declared in package directive in struts.xml and has "/" for its namespace and extends "struts-default". It also declares @Result so that it responses with jsp files corresponding the string values returned by its execute() method. In our struts.xml, the following struts setting is configured along with other necessary configurations that are needed for convention-plugin. <constant name="struts.action.extension" value=","/> When accessing /my_context/none_existing_path, the request apparently hits this Index class and the contents of the jsp declared in the Index's @Result section gets returned. However, if we provide /my_context/, we receive the following error: HTTP Status 404-There is no Action mapped for namespace[/] and action name [] associated with context path [/my_context]. We want to know the reason why accessing /my_context/none_existing_path, where none_existing_path has no matching action, can fallback to Index class, but error is returned when when the URL requested is just /my_context/. Currently, our convention-plugin settings are declared as follows: <constant name="struts.convention.package.locators.basePackage" value="com.example"/> <constant name="struts.convention.package.locators" value="action"/> Strangely, if we changed the value of the struts.convention.package.locators.basePackage to om.example.common, in which the aforementioned Index file can be immediately found by narrowing the search scope, requesting /my_context/ displays the content of the jsps declared in @Result section of the Index class. However, as our action classes are distributed throughout the com.example.[a-z].action packages, where [a-z] represents the large volume of directories we have in our package structure, we cannot use this trick as a workaround. We have also tried placing index.jsp at the top level of the class path, and have the index.jsp redirect to /my_context/index, which worked but not what we want. Could this be a bug? We appreciate your responses. Thank you in advance. EDIT: JIRA registered, problem solved (from Struts 2.3.12 up)

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• Creating multiple instances of a generic database

  - by sagekilla

  Hi all, currently I'm trying to have a setup where a generic database is distributed to students. They would develop an application using this database (Say a shopping cart application), submit their project onto our server, and then it would be graded automatically. These databases are being run in Microsoft SQL Server 2005. We're using user instances to instantiate each database, and multiple requests could be serviced at once. But, the problem is when more than one student submitted a project to be graded, the first database to be instantiated would be the only one and would overwrite all other copies that were currently open. So if stu1 modified his database and stu2 and stu3 had their projects being graded concurrently, at the end of the grading stu1, stu2, and stu3 would have identical DB's at the end. Is there any way I can have multiple independent copies of a generic database, each of which I can load concurrently and modify without having any changes made to any one affecting the others? I did a little reading, and thought it might be possible to do something along the lines of: Student submits project Attach the database with unique db name (specified by student) Do all necessary operations Detach the database I'm unsure if this would fix our problem or be possible, so any help would be much appreciated!

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• Mysql - wondering about scaling a twitter-like application ?

  - by user246114

  Hi, I'm developing an app that is vaguely similar to twitter, in that it allows users to follow one another. I wanted to do this using google app engine, for its scalability promises, but it's proving kind of difficult to get running for a few different reasons. I'd basically like to have a _users table, and a _followers table. Users go into the users table, follower relationships go into _followers. The problem is that each row in the users table will probably have like 100 corresponding records in the _followers table as users start following one another. So the number of rows is going to explode quickly. Using app engine, the volume [shouldn't] be a problem. If I go with mysql, and I do actually start to get some traction, how do I scale this up? Am I going to just end up moving to a distributed database in the end anyway? Should I fight it out with google app engine? I read that Twitter was using mysql, and they've run into this problem, and are now switching to cassandra. Thanks

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• MATLAB: What is an appropriate Data Structure for a Matrix with Random Variable Entries?

  - by user568249

  I'm currently working in an area that is related to simulation and trying to design a data structure that can include random variables within matrices. To motivate this let me say I have the following matrix: [a b; c d] I want to find a data structure that will allow for a, b, c, d to either be real numbers or random variables. As an example, let's say that a = 1, b = -1, c = 2 but let d be a normally distributed random variable with mean 0 and SD 1. The data structure that I have in mind will give no value to d. However, I also want to be able to design a function that can take in the structure, simulate an uniform(0,1), obtain a value for d using an inverse CDF and then spit out an actual matrix. I have several ideas to do this (all related to the MATLAB icdf function) but would like to know how more experienced programmers would do this. In this application, it's important that the structure is as "lean" as possible since I will be working with very very large matrices and memory will be an issue.

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• Building applications with WPF, MVVM and Prism(aka CAG)

  - by skjagini

  In this article I am going to walk through an application using WPF and Prism (aka composite application guidance, CAG) which simulates engaging a taxi (cab).  The rules are simple, the app would have3 screens A login screen to authenticate the user An information screen. A screen to engage the cab and roam around and calculating the total fare Metered Rate of Fare The meter is required to be engaged when a cab is occupied by anyone $3.00 upon entry $0.35 for each additional unit The unit fare is: one-fifth of a mile, when the cab is traveling at 6 miles an hour or more; or 60 seconds when not in motion or traveling at less than 12 miles per hour. Night surcharge of $.50 after 8:00 PM & before 6:00 AM Peak hour Weekday Surcharge of $1.00 Monday - Friday after 4:00 PM & before 8:00 PM New York State Tax Surcharge of $.50 per ride. Example: Friday (2010-10-08) 5:30pm Start at Lexington Ave & E 57th St End at Irving Pl & E 15th St Start = $3.00 Travels 2 miles at less than 6 mph for 15 minutes = $3.50 Travels at more than 12 mph for 5 minutes = $1.75 Peak hour Weekday Surcharge = $1.00 (ride started at 5:30 pm) New York State Tax Surcharge = $0.50 Before we dive into the app, I would like to give brief description about the framework.  If you want to jump on to the source code, scroll all the way to the end of the post. MVVM MVVM pattern is in no way related to the usage of PRISM in your application and should be considered if you are using WPF irrespective of PRISM or not. Lets say you are not familiar with MVVM, your typical UI would involve adding some UI controls like text boxes, a button, double clicking on the button,  generating event handler, calling a method from business layer and updating the user interface, it works most of the time for developing small scale applications. The problem with this approach is that there is some amount of code specific to business logic wrapped in UI specific code which is hard to unit test it, mock it and MVVM helps to solve the exact problem. MVVM stands for Model(M) – View(V) – ViewModel(VM),  based on the interactions with in the three parties it should be called VVMM,  MVVM sounds more like MVC (Model-View-Controller) so the name. Why it should be called VVMM: View – View Model - Model WPF allows to create user interfaces using XAML and MVVM takes it to the next level by allowing complete separation of user interface and business logic. In WPF each view will have a property, DataContext when set to an instance of a class (which happens to be your view model) provides the data the view is interested in, i.e., view interacts with view model and at the same time view model interacts with view through DataContext. Sujith, if view and view model are interacting directly with each other how does MVVM is helping me separation of concerns? Well, the catch is DataContext is of type Object, since it is of type object view doesn’t know exact type of view model allowing views and views models to be loosely coupled. View models aggregate data from models (data access layer, services, etc) and make it available for views through properties, methods etc, i.e., View Models interact with Models. PRISM Prism is provided by Microsoft Patterns and Practices team and it can be downloaded from codeplex for source code,  samples and documentation on msdn.  The name composite implies, to compose user interface from different modules (views) without direct dependencies on each other, again allowing  loosely coupled development. Well Sujith, I can already do that with user controls, why shall I learn another framework?  That’s correct, you can decouple using user controls, but you still have to manage some amount of coupling, like how to do you communicate between the controls, how do you subscribe/unsubscribe, loading/unloading views dynamically. Prism is not a replacement for user controls, provides the following features which greatly help in designing the composite applications. Dependency Injection (DI)/ Inversion of Control (IoC) Modules Regions Event Aggregator  Commands Simply put, MVVM helps building a single view and Prism helps building an application using the views There are other open source alternatives to Prism, like MVVMLight, Cinch, take a look at them as well. Lets dig into the source code.  1. Solution The solution is made of the following projects Framework: Holds the common functionality in building applications using WPF and Prism TaxiClient: Start up project, boot strapping and app styling TaxiCommon: Helps with the business logic TaxiModules: Holds the meat of the application with views and view models TaxiTests: To test the application 2. DI / IoC Dependency Injection (DI) as the name implies refers to injecting dependencies and Inversion of Control (IoC) means the calling code has no direct control on the dependencies, opposite of normal way of programming where dependencies are passed by caller, i.e inversion; aside from some differences in terminology the concept is same in both the cases. The idea behind DI/IoC pattern is to reduce the amount of direct coupling between different components of the application, the higher the dependency the more tightly coupled the application resulting in code which is hard to modify, unit test and mock.  Initializing Dependency Injection through BootStrapper TaxiClient is the starting project of the solution and App (App.xaml)  is the starting class that gets called when you run the application. From the App’s OnStartup method we will invoke BootStrapper.   namespace TaxiClient { /// <summary> /// Interaction logic for App.xaml /// </summary> public partial class App : Application { protected override void OnStartup(StartupEventArgs e) { base.OnStartup(e);   (new BootStrapper()).Run(); } } } BootStrapper is your contact point for initializing the application including dependency injection, creating Shell and other frameworks. We are going to use Unity for DI and there are lot of open source DI frameworks like Spring.Net, StructureMap etc with different feature set  and you can choose a framework based on your preferences. Note that Prism comes with in built support for Unity, for example we are deriving from UnityBootStrapper in our case and for any other DI framework you have to extend the Prism appropriately   namespace TaxiClient { public class BootStrapper: UnityBootstrapper { protected override IModuleCatalog CreateModuleCatalog() { return new ConfigurationModuleCatalog(); } protected override DependencyObject CreateShell() { Framework.FrameworkBootStrapper.Run(Container, Application.Current.Dispatcher);   Shell shell = new Shell(); shell.ResizeMode = ResizeMode.NoResize; shell.Show();   return shell; } } } Lets take a look into  FrameworkBootStrapper to check out how to register with unity container. namespace Framework { public class FrameworkBootStrapper { public static void Run(IUnityContainer container, Dispatcher dispatcher) { UIDispatcher uiDispatcher = new UIDispatcher(dispatcher); container.RegisterInstance<IDispatcherService>(uiDispatcher);   container.RegisterType<IInjectSingleViewService, InjectSingleViewService>( new ContainerControlledLifetimeManager());   . . . } } } In the above code we are registering two components with unity container. You shall observe that we are following two different approaches, RegisterInstance and RegisterType.  With RegisterInstance we are registering an existing instance and the same instance will be returned for every request made for IDispatcherService   and with RegisterType we are requesting unity container to create an instance for us when required, i.e., when I request for an instance for IInjectSingleViewService, unity will create/return an instance of InjectSingleViewService class and with RegisterType we can configure the life time of the instance being created. With ContaienrControllerLifetimeManager, the unity container caches the instance and reuses for any subsequent requests, without recreating a new instance. Lets take a look into FareViewModel.cs and it’s constructor. The constructor takes one parameter IEventAggregator and if you try to find all references in your solution for IEventAggregator, you will not find a single location where an instance of EventAggregator is passed directly to the constructor. The compiler still finds an instance and works fine because Prism is already configured when used with Unity container to return an instance of EventAggregator when requested for IEventAggregator and in this particular case it is called constructor injection. public class FareViewModel:ObservableBase, IDataErrorInfo { ... private IEventAggregator _eventAggregator;   public FareViewModel(IEventAggregator eventAggregator) { _eventAggregator = eventAggregator; InitializePropertyNames(); InitializeModel(); PropertyChanged += OnPropertyChanged; } ... 3. Shell Shells are very similar in operation to Master Pages in asp.net or MDI in Windows Forms. And shells contain regions which display the views, you can have as many regions as you wish in a given view. You can also nest regions. i.e, one region can load a view which in itself may contain other regions. We have to create a shell at the start of the application and are doing it by overriding CreateShell method from BootStrapper From the following Shell.xaml you shall notice that we have two content controls with Region names as ‘MenuRegion’ and ‘MainRegion’.  The idea here is that you can inject any user controls into the regions dynamically, i.e., a Menu User Control for MenuRegion and based on the user action you can load appropriate view into MainRegion.    <Window x:Class="TaxiClient.Shell" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:Regions="clr-namespace:Microsoft.Practices.Prism.Regions;assembly=Microsoft.Practices.Prism" Title="Taxi" Height="370" Width="800"> <Grid Margin="2"> <ContentControl Regions:RegionManager.RegionName="MenuRegion" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" HorizontalContentAlignment="Stretch" VerticalContentAlignment="Stretch" />   <ContentControl Grid.Row="1" Regions:RegionManager.RegionName="MainRegion" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" HorizontalContentAlignment="Stretch" VerticalContentAlignment="Stretch" /> <!--<Border Grid.ColumnSpan="2" BorderThickness="2" CornerRadius="3" BorderBrush="LightBlue" />-->   </Grid> </Window> 4. Modules Prism provides the ability to build composite applications and modules play an important role in it. For example if you are building a Mortgage Loan Processor application with 3 components, i.e. customer’s credit history,  existing mortgages, new home/loan information; and consider that the customer’s credit history component involves gathering data about his/her address, background information, job details etc. The idea here using Prism modules is to separate the implementation of these 3 components into their own visual studio projects allowing to build components with no dependency on each other and independently. If we need to add another component to the application, the component can be developed by in house team or some other team in the organization by starting with a new Visual Studio project and adding to the solution at the run time with very little knowledge about the application. Prism modules are defined by implementing the IModule interface and each visual studio project to be considered as a module should implement the IModule interface.  From the BootStrapper.cs you shall observe that we are overriding the method by returning a ConfiguratingModuleCatalog which returns the modules that are registered for the application using the app.config file  and you can also add module using code. Lets take a look into configuration file.   <?xml version="1.0"?> <configuration> <configSections> <section name="modules" type="Microsoft.Practices.Prism.Modularity.ModulesConfigurationSection, Microsoft.Practices.Prism"/> </configSections> <modules> <module assemblyFile="TaxiModules.dll" moduleType="TaxiModules.ModuleInitializer, TaxiModules" moduleName="TaxiModules"/> </modules> </configuration> Here we are adding TaxiModules project to our solution and TaxiModules.ModuleInitializer implements IModule interface   5. Module Mapper With Prism modules you can dynamically add or remove modules from the regions, apart from that Prism also provides API to control adding/removing the views from a region within the same module. Taxi Information Screen: Engage the Taxi Screen: The sample application has two screens, ‘Taxi Information’ and ‘Engage the Taxi’ and they both reside in same module, TaxiModules. ‘Engage the Taxi’ is again made of two user controls, FareView on the left and TotalView on the right. We have created a Shell with two regions, MenuRegion and MainRegion with menu loaded into MenuRegion. We can create a wrapper user control called EngageTheTaxi made of FareView and TotalView and load either TaxiInfo or EngageTheTaxi into MainRegion based on the user action. Though it will work it tightly binds the user controls and for every combination of user controls, we need to create a dummy wrapper control to contain them. Instead we can apply the principles we learned so far from Shell/regions and introduce another template (LeftAndRightRegionView.xaml) made of two regions Region1 (left) and Region2 (right) and load  FareView and TotalView dynamically.  To help with loading of the views dynamically I have introduce an helper an interface, IInjectSingleViewService,  idea suggested by Mike Taulty, a must read blog for .Net developers. using System; using System.Collections.Generic; using System.ComponentModel;   namespace Framework.PresentationUtility.Navigation {   public interface IInjectSingleViewService : INotifyPropertyChanged { IEnumerable<CommandViewDefinition> Commands { get; } IEnumerable<ModuleViewDefinition> Modules { get; }   void RegisterViewForRegion(string commandName, string viewName, string regionName, Type viewType); void ClearViewFromRegion(string viewName, string regionName); void RegisterModule(string moduleName, IList<ModuleMapper> moduleMappers); } } The Interface declares three methods to work with views: RegisterViewForRegion: Registers a view with a particular region. You can register multiple views and their regions under one command.  When this particular command is invoked all the views registered under it will be loaded into their regions. ClearViewFromRegion: To unload a specific view from a region. RegisterModule: The idea is when a command is invoked you can load the UI with set of controls in their default position and based on the user interaction, you can load different contols in to different regions on the fly.  And it is supported ModuleViewDefinition and ModuleMappers as shown below. namespace Framework.PresentationUtility.Navigation { public class ModuleViewDefinition { public string ModuleName { get; set; } public IList<ModuleMapper> ModuleMappers; public ICommand Command { get; set; } }   public class ModuleMapper { public string ViewName { get; set; } public string RegionName { get; set; } public Type ViewType { get; set; } } } 6. Event Aggregator Prism event aggregator enables messaging between components as in Observable pattern, Notifier notifies the Observer which receives notification it is interested in. When it comes to Observable pattern, Observer has to unsubscribes for notifications when it no longer interested in notifications, which allows the Notifier to remove the Observer’s reference from it’s local cache. Though .Net has managed garbage collection it cannot remove inactive the instances referenced by an active instance resulting in memory leak, keeping the Observers in memory as long as Notifier stays in memory.  Developers have to be very careful to unsubscribe when necessary and it often gets overlooked, to overcome these problems Prism Event Aggregator uses weak references to cache the reference (Observer in this case)  and releases the reference (memory) once the instance goes out of scope. Using event aggregator is very simple, declare a generic type of CompositePresenationEvent by inheriting from it. using Microsoft.Practices.Prism.Events; using TaxiCommon.BAO;   namespace TaxiCommon.CompositeEvents { public class TaxiOnMoveEvent:CompositePresentationEvent<TaxiOnMove> { } }   TaxiOnMove.cs includes the properties which we want to exchange between the parties, FareView and TotalView. using System;   namespace TaxiCommon.BAO { public class TaxiOnMove { public TimeSpan MinutesAtTweleveMPH { get; set; } public double MilesAtSixMPH { get; set; } } }   Lets take a look into FareViewodel (Notifier) and how it raises the event.  Here we are raising the event by getting the event through GetEvent<..>() and publishing it with the payload private void OnAddMinutes(object obj) { TaxiOnMove payload = new TaxiOnMove(); if(MilesAtSixMPH != null) payload.MilesAtSixMPH = MilesAtSixMPH.Value; if(MinutesAtTweleveMPH != null) payload.MinutesAtTweleveMPH = new TimeSpan(0,0,MinutesAtTweleveMPH.Value,0);   _eventAggregator.GetEvent<TaxiOnMoveEvent>().Publish(payload); ResetMinutesAndMiles(); } And TotalViewModel(Observer) subscribes to notifications by getting the event through GetEvent<..>() namespace TaxiModules.ViewModels { public class TotalViewModel:ObservableBase { .... private IEventAggregator _eventAggregator;   public TotalViewModel(IEventAggregator eventAggregator) { _eventAggregator = eventAggregator; ... }   private void SubscribeToEvents() { _eventAggregator.GetEvent<TaxiStartedEvent>() .Subscribe(OnTaxiStarted, ThreadOption.UIThread,false,(filter) => true); _eventAggregator.GetEvent<TaxiOnMoveEvent>() .Subscribe(OnTaxiMove, ThreadOption.UIThread, false, (filter) => true); _eventAggregator.GetEvent<TaxiResetEvent>() .Subscribe(OnTaxiReset, ThreadOption.UIThread, false, (filter) => true); }   ... private void OnTaxiMove(TaxiOnMove taxiOnMove) { OnMoveFare fare = new OnMoveFare(taxiOnMove); Fares.Add(fare); SetTotalFare(new []{fare}); }   .... 7. MVVM through example In this section we are going to look into MVVM implementation through example.  I have all the modules declared in a single project, TaxiModules, again it is not necessary to have them into one project. Once the user logs into the application, will be greeted with the ‘Engage the Taxi’ screen which is made of two user controls, FareView.xaml and TotalView.Xaml. As you can see from the solution explorer, each of them have their own code behind files and  ViewModel classes, FareViewMode.cs, TotalViewModel.cs Lets take a look in to the FareView and how it interacts with FareViewModel using MVVM implementation. FareView.xaml acts as a view and FareViewMode.cs is it’s view model. The FareView code behind class   namespace TaxiModules.Views { /// <summary> /// Interaction logic for FareView.xaml /// </summary> public partial class FareView : UserControl { public FareView(FareViewModel viewModel) { InitializeComponent(); this.Loaded += (s, e) => { this.DataContext = viewModel; }; } } } The FareView is bound to FareViewModel through the data context  and you shall observe that DataContext is of type Object, i.e. the FareView doesn’t really know the type of ViewModel (FareViewModel). This helps separation of View and ViewModel as View and ViewModel are independent of each other, you can bind FareView to FareViewModel2 as well and the application compiles just fine. Lets take a look into FareView xaml file  <UserControl x:Class="TaxiModules.Views.FareView" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:Toolkit="clr-namespace:Microsoft.Windows.Controls;assembly=WPFToolkit" xmlns:Commands="clr-namespace:Microsoft.Practices.Prism.Commands;assembly=Microsoft.Practices.Prism"> <Grid Margin="10" > ....   <Border Style="{DynamicResource innerBorder}" Grid.Row="0" Grid.Column="0" Grid.RowSpan="11" Grid.ColumnSpan="2" Panel.ZIndex="1"/>   <Label Grid.Row="0" Content="Engage the Taxi" Style="{DynamicResource innerHeader}"/> <Label Grid.Row="1" Content="Select the State"/> <ComboBox Grid.Row="1" Grid.Column="1" ItemsSource="{Binding States}" Height="auto"> <ComboBox.ItemTemplate> <DataTemplate> <TextBlock Text="{Binding Name}"/> </DataTemplate> </ComboBox.ItemTemplate> <ComboBox.SelectedItem> <Binding Path="SelectedState" Mode="TwoWay"/> </ComboBox.SelectedItem> </ComboBox> <Label Grid.Row="2" Content="Select the Date of Entry"/> <Toolkit:DatePicker Grid.Row="2" Grid.Column="1" SelectedDate="{Binding DateOfEntry, ValidatesOnDataErrors=true}" /> <Label Grid.Row="3" Content="Enter time 24hr format"/> <TextBox Grid.Row="3" Grid.Column="1" Text="{Binding TimeOfEntry, TargetNullValue=''}"/> <Button Grid.Row="4" Grid.Column="1" Content="Start the Meter" Commands:Click.Command="{Binding StartMeterCommand}" />   <Label Grid.Row="5" Content="Run the Taxi" Style="{DynamicResource innerHeader}"/> <Label Grid.Row="6" Content="Number of Miles &lt;@6mph"/> <TextBox Grid.Row="6" Grid.Column="1" Text="{Binding MilesAtSixMPH, TargetNullValue='', ValidatesOnDataErrors=true}"/> <Label Grid.Row="7" Content="Number of Minutes @12mph"/> <TextBox Grid.Row="7" Grid.Column="1" Text="{Binding MinutesAtTweleveMPH, TargetNullValue=''}"/> <Button Grid.Row="8" Grid.Column="1" Content="Add Minutes and Miles " Commands:Click.Command="{Binding AddMinutesCommand}"/> <Label Grid.Row="9" Content="Other Operations" Style="{DynamicResource innerHeader}"/> <Button Grid.Row="10" Grid.Column="1" Content="Reset the Meter" Commands:Click.Command="{Binding ResetCommand}"/>   </Grid> </UserControl> The highlighted code from the above code shows data binding, for example ComboBox which displays list of states has it’s ItemsSource bound to States property, with DataTemplate bound to Name and SelectedItem  to SelectedState. You might be wondering what are all these properties and how it is able to bind to them.  The answer lies in data context, i.e., when you bound a control, WPF looks for data context on the root object (Grid in this case) and if it can’t find data context it will look into root’s root, i.e. FareView UserControl and it is bound to FareViewModel.  Each of those properties have be declared on the ViewModel for the View to bind correctly. To put simply, View is bound to ViewModel through data context of type object and every control that is bound on the View actually binds to the public property on the ViewModel. Lets look into the ViewModel code (the following code is not an exact copy of FareViewMode.cs, pasted relevant code for this section)   namespace TaxiModules.ViewModels { public class FareViewModel:ObservableBase, IDataErrorInfo { public List<USState> States { get { return USStates.StateList; } }   public USState SelectedState { get { return _selectedState; } set { _selectedState = value; RaisePropertyChanged(_selectedStatePropertyName); } }   public DateTime? DateOfEntry { get { return _dateOfEntry; } set { _dateOfEntry = value; RaisePropertyChanged(_dateOfEntryPropertyName); } }   public TimeSpan? TimeOfEntry { get { return _timeOfEntry; } set { _timeOfEntry = value; RaisePropertyChanged(_timeOfEntryPropertyName); } }   public double? MilesAtSixMPH { get { return _milesAtSixMPH; } set { _milesAtSixMPH = value; RaisePropertyChanged(_distanceAtSixMPHPropertyName); } }   public int? MinutesAtTweleveMPH { get { return _minutesAtTweleveMPH; } set { _minutesAtTweleveMPH = value; RaisePropertyChanged(_minutesAtTweleveMPHPropertyName); } }   public ICommand StartMeterCommand { get { if(_startMeterCommand == null) { _startMeterCommand = new DelegateCommand<object>(OnStartMeter, CanStartMeter); } return _startMeterCommand; } }   public ICommand AddMinutesCommand { get { if(_addMinutesCommand == null) { _addMinutesCommand = new DelegateCommand<object>(OnAddMinutes, CanAddMinutes); } return _addMinutesCommand; } }   public ICommand ResetCommand { get { if(_resetCommand == null) { _resetCommand = new DelegateCommand<object>(OnResetCommand); } return _resetCommand; } }   } private void OnStartMeter(object obj) { _eventAggregator.GetEvent<TaxiStartedEvent>().Publish( new TaxiStarted() { EngagedOn = DateOfEntry.Value.Date + TimeOfEntry.Value, EngagedState = SelectedState.Value });   _isMeterStarted = true; OnPropertyChanged(this,null); } And views communicate user actions like button clicks, tree view item selections, etc using commands. When user clicks on ‘Start the Meter’ button it invokes the method StartMeterCommand, which calls the method OnStartMeter which publishes the event to TotalViewModel using event aggregator  and TaxiStartedEvent. namespace TaxiModules.ViewModels { public class TotalViewModel:ObservableBase { ... private IEventAggregator _eventAggregator;   public TotalViewModel(IEventAggregator eventAggregator) { _eventAggregator = eventAggregator;   InitializePropertyNames(); InitializeModel(); SubscribeToEvents(); }   public decimal? TotalFare { get { return _totalFare; } set { _totalFare = value; RaisePropertyChanged(_totalFarePropertyName); } } .... private void SubscribeToEvents() { _eventAggregator.GetEvent<TaxiStartedEvent>().Subscribe(OnTaxiStarted, ThreadOption.UIThread,false,(filter) => true); _eventAggregator.GetEvent<TaxiOnMoveEvent>().Subscribe(OnTaxiMove, ThreadOption.UIThread, false, (filter) => true); _eventAggregator.GetEvent<TaxiResetEvent>().Subscribe(OnTaxiReset, ThreadOption.UIThread, false, (filter) => true); }   private void OnTaxiStarted(TaxiStarted taxiStarted) { Fares.Add(new EntryFare()); Fares.Add(new StateTaxFare(taxiStarted)); Fares.Add(new NightSurchargeFare(taxiStarted)); Fares.Add(new PeakHourWeekdayFare(taxiStarted));   SetTotalFare(Fares); }   private void SetTotalFare(IEnumerable<IFare> fares) { TotalFare = (_totalFare ?? 0) + TaxiFareHelper.GetTotalFare(fares); } ....   } }   TotalViewModel subscribes to events, TaxiStartedEvent and rest. When TaxiStartedEvent gets invoked it calls the OnTaxiStarted method which sets the total fare which includes entry fee, state tax, nightly surcharge, peak hour weekday fare.   Note that TotalViewModel derives from ObservableBase which implements the method RaisePropertyChanged which we are invoking in Set of TotalFare property, i.e, once we update the TotalFare property it raises an the event that  allows the TotalFare text box to fetch the new value through the data context. ViewModel is communicating with View through data context and it has no knowledge about View, helping in loose coupling of ViewModel and View.   I have attached the source code (.Net 4.0, Prism 4.0, VS 2010) , download and play with it and don’t forget to leave your comments.  

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• Capturing and Transforming ASP.NET Output with Response.Filter

  - by Rick Strahl

  During one of my Handlers and Modules session at DevConnections this week one of the attendees asked a question that I didn’t have an immediate answer for. Basically he wanted to capture response output completely and then apply some filtering to the output – effectively injecting some additional content into the page AFTER the page had completely rendered. Specifically the output should be captured from anywhere – not just a page and have this code injected into the page. Some time ago I posted some code that allows you to capture ASP.NET Page output by overriding the Render() method, capturing the HtmlTextWriter() and reading its content, modifying the rendered data as text then writing it back out. I’ve actually used this approach on a few occasions and it works fine for ASP.NET pages. But this obviously won’t work outside of the Page class environment and it’s not really generic – you have to create a custom page class in order to handle the output capture. [updated 11/16/2009 – updated ResponseFilterStream implementation and a few additional notes based on comments] Enter Response.Filter However, ASP.NET includes a Response.Filter which can be used – well to filter output. Basically Response.Filter is a stream through which the OutputStream is piped back to the Web Server (indirectly). As content is written into the Response object, the filter stream receives the appropriate Stream commands like Write, Flush and Close as well as read operations although for a Response.Filter that’s uncommon to be hit. The Response.Filter can be programmatically replaced at runtime which allows you to effectively intercept all output generation that runs through ASP.NET. A common Example: Dynamic GZip Encoding A rather common use of Response.Filter hooking up code based, dynamic  GZip compression for requests which is dead simple by applying a GZipStream (or DeflateStream) to Response.Filter. The following generic routines can be used very easily to detect GZip capability of the client and compress response output with a single line of code and a couple of library helper routines: WebUtils.GZipEncodePage(); which is handled with a few lines of reusable code and a couple of static helper methods: /// <summary> ///Sets up the current page or handler to use GZip through a Response.Filter ///IMPORTANT:  ///You have to call this method before any output is generated! /// </summary> public static void GZipEncodePage() {     HttpResponse Response = HttpContext.Current.Response;     if(IsGZipSupported())     {         stringAcceptEncoding = HttpContext.Current.Request.Headers["Accept-Encoding"];         if(AcceptEncoding.Contains("deflate"))         {             Response.Filter = newSystem.IO.Compression.DeflateStream(Response.Filter,                                        System.IO.Compression.CompressionMode.Compress);             Response.AppendHeader("Content-Encoding", "deflate");         }         else        {             Response.Filter = newSystem.IO.Compression.GZipStream(Response.Filter,                                       System.IO.Compression.CompressionMode.Compress);             Response.AppendHeader("Content-Encoding", "gzip");                            }     }     // Allow proxy servers to cache encoded and unencoded versions separately    Response.AppendHeader("Vary", "Content-Encoding"); } /// <summary> /// Determines if GZip is supported /// </summary> /// <returns></returns> public static bool IsGZipSupported() { string AcceptEncoding = HttpContext.Current.Request.Headers["Accept-Encoding"]; if (!string.IsNullOrEmpty(AcceptEncoding) && (AcceptEncoding.Contains("gzip") || AcceptEncoding.Contains("deflate"))) return true; return false; } GZipStream and DeflateStream are streams that are assigned to Response.Filter and by doing so apply the appropriate compression on the active Response. Response.Filter content is chunked So to implement a Response.Filter effectively requires only that you implement a custom stream and handle the Write() method to capture Response output as it’s written. At first blush this seems very simple – you capture the output in Write, transform it and write out the transformed content in one pass. And that indeed works for small amounts of content. But you see, the problem is that output is written in small buffer chunks (a little less than 16k it appears) rather than just a single Write() statement into the stream, which makes perfect sense for ASP.NET to stream data back to IIS in smaller chunks to minimize memory usage en route. Unfortunately this also makes it a more difficult to implement any filtering routines since you don’t directly get access to all of the response content which is problematic especially if those filtering routines require you to look at the ENTIRE response in order to transform or capture the output as is needed for the solution the gentleman in my session asked for. So in order to address this a slightly different approach is required that basically captures all the Write() buffers passed into a cached stream and then making the stream available only when it’s complete and ready to be flushed. As I was thinking about the implementation I also started thinking about the few instances when I’ve used Response.Filter implementations. Each time I had to create a new Stream subclass and create my custom functionality but in the end each implementation did the same thing – capturing output and transforming it. I thought there should be an easier way to do this by creating a re-usable Stream class that can handle stream transformations that are common to Response.Filter implementations. Creating a semi-generic Response Filter Stream Class What I ended up with is a ResponseFilterStream class that provides a handful of Events that allow you to capture and/or transform Response content. The class implements a subclass of Stream and then overrides Write() and Flush() to handle capturing and transformation operations. By exposing events it’s easy to hook up capture or transformation operations via single focused methods. ResponseFilterStream exposes the following events: CaptureStream, CaptureString Captures the output only and provides either a MemoryStream or String with the final page output. Capture is hooked to the Flush() operation of the stream. TransformStream, TransformString Allows you to transform the complete response output with events that receive a MemoryStream or String respectively and can you modify the output then return it back as a return value. The transformed output is then written back out in a single chunk to the response output stream. These events capture all output internally first then write the entire buffer into the response. TransformWrite, TransformWriteString Allows you to transform the Response data as it is written in its original chunk size in the Stream’s Write() method. Unlike TransformStream/TransformString which operate on the complete output, these events only see the current chunk of data written. This is more efficient as there’s no caching involved, but can cause problems due to searched content splitting over multiple chunks. Using this implementation, creating a custom Response.Filter transformation becomes as simple as the following code. To hook up the Response.Filter using the MemoryStream version event: ResponseFilterStream filter = new ResponseFilterStream(Response.Filter); filter.TransformStream += filter_TransformStream; Response.Filter = filter; and the event handler to do the transformation: MemoryStream filter_TransformStream(MemoryStream ms) { Encoding encoding = HttpContext.Current.Response.ContentEncoding; string output = encoding.GetString(ms.ToArray()); output = FixPaths(output); ms = new MemoryStream(output.Length); byte[] buffer = encoding.GetBytes(output); ms.Write(buffer,0,buffer.Length); return ms; } private string FixPaths(string output) { string path = HttpContext.Current.Request.ApplicationPath; // override root path wonkiness if (path == "/") path = ""; output = output.Replace("\"~/", "\"" + path + "/").Replace("'~/", "'" + path + "/"); return output; } The idea of the event handler is that you can do whatever you want to the stream and return back a stream – either the same one that’s been modified or a brand new one – which is then sent back to as the final response. The above code can be simplified even more by using the string version events which handle the stream to string conversions for you: ResponseFilterStream filter = new ResponseFilterStream(Response.Filter); filter.TransformString += filter_TransformString; Response.Filter = filter; and the event handler to do the transformation calling the same FixPaths method shown above: string filter_TransformString(string output) { return FixPaths(output); } The events for capturing output and capturing and transforming chunks work in a very similar way. By using events to handle the transformations ResponseFilterStream becomes a reusable component and we don’t have to create a new stream class or subclass an existing Stream based classed. By the way, the example used here is kind of a cool trick which transforms “~/” expressions inside of the final generated HTML output – even in plain HTML controls not HTML controls – and transforms them into the appropriate application relative path in the same way that ResolveUrl would do. So you can write plain old HTML like this: <a href=”~/default.aspx”>Home</a>  and have it turned into: <a href=”/myVirtual/default.aspx”>Home</a>  without having to use an ASP.NET control like Hyperlink or Image or having to constantly use: <img src=”<%= ResolveUrl(“~/images/home.gif”) %>” /> in MVC applications (which frankly is one of the most annoying things about MVC especially given the path hell that extension-less and endpoint-less URLs impose). I can’t take credit for this idea. While discussing the Response.Filter issues on Twitter a hint from Dylan Beattie who pointed me at one of his examples which does something similar. I thought the idea was cool enough to use an example for future demos of Response.Filter functionality in ASP.NET next I time I do the Modules and Handlers talk (which was great fun BTW). How practical this is is debatable however since there’s definitely some overhead to using a Response.Filter in general and especially on one that caches the output and the re-writes it later. Make sure to test for performance anytime you use Response.Filter hookup and make sure it' doesn’t end up killing perf on you. You’ve been warned :-}. How does ResponseFilterStream work? The big win of this implementation IMHO is that it’s a reusable  component – so for implementation there’s no new class, no subclassing – you simply attach to an event to implement an event handler method with a straight forward signature to retrieve the stream or string you’re interested in. The implementation is based on a subclass of Stream as is required in order to handle the Response.Filter requirements. What’s different than other implementations I’ve seen in various places is that it supports capturing output as a whole to allow retrieving the full response output for capture or modification. The exception are the TransformWrite and TransformWrite events which operate only active chunk of data written by the Response. For captured output, the Write() method captures output into an internal MemoryStream that is cached until writing is complete. So Write() is called when ASP.NET writes to the Response stream, but the filter doesn’t pass on the Write immediately to the filter’s internal stream. The data is cached and only when the Flush() method is called to finalize the Stream’s output do we actually send the cached stream off for transformation (if the events are hooked up) and THEN finally write out the returned content in one big chunk. Here’s the implementation of ResponseFilterStream: /// <summary> /// A semi-generic Stream implementation for Response.Filter with /// an event interface for handling Content transformations via /// Stream or String. /// <remarks> /// Use with care for large output as this implementation copies /// the output into a memory stream and so increases memory usage. /// </remarks> /// </summary> public class ResponseFilterStream : Stream { /// <summary> /// The original stream /// </summary> Stream _stream; /// <summary> /// Current position in the original stream /// </summary> long _position; /// <summary> /// Stream that original content is read into /// and then passed to TransformStream function /// </summary> MemoryStream _cacheStream = new MemoryStream(5000); /// <summary> /// Internal pointer that that keeps track of the size /// of the cacheStream /// </summary> int _cachePointer = 0; /// <summary> /// /// </summary> /// <param name="responseStream"></param> public ResponseFilterStream(Stream responseStream) { _stream = responseStream; } /// <summary> /// Determines whether the stream is captured /// </summary> private bool IsCaptured { get { if (CaptureStream != null || CaptureString != null || TransformStream != null || TransformString != null) return true; return false; } } /// <summary> /// Determines whether the Write method is outputting data immediately /// or delaying output until Flush() is fired. /// </summary> private bool IsOutputDelayed { get { if (TransformStream != null || TransformString != null) return true; return false; } } /// <summary> /// Event that captures Response output and makes it available /// as a MemoryStream instance. Output is captured but won't /// affect Response output. /// </summary> public event Action<MemoryStream> CaptureStream; /// <summary> /// Event that captures Response output and makes it available /// as a string. Output is captured but won't affect Response output. /// </summary> public event Action<string> CaptureString; /// <summary> /// Event that allows you transform the stream as each chunk of /// the output is written in the Write() operation of the stream. /// This means that that it's possible/likely that the input /// buffer will not contain the full response output but only /// one of potentially many chunks. /// /// This event is called as part of the filter stream's Write() /// operation. /// </summary> public event Func<byte[], byte[]> TransformWrite; /// <summary> /// Event that allows you to transform the response stream as /// each chunk of bytep[] output is written during the stream's write /// operation. This means it's possibly/likely that the string /// passed to the handler only contains a portion of the full /// output. Typical buffer chunks are around 16k a piece. /// /// This event is called as part of the stream's Write operation. /// </summary> public event Func<string, string> TransformWriteString; /// <summary> /// This event allows capturing and transformation of the entire /// output stream by caching all write operations and delaying final /// response output until Flush() is called on the stream. /// </summary> public event Func<MemoryStream, MemoryStream> TransformStream; /// <summary> /// Event that can be hooked up to handle Response.Filter /// Transformation. Passed a string that you can modify and /// return back as a return value. The modified content /// will become the final output. /// </summary> public event Func<string, string> TransformString; protected virtual void OnCaptureStream(MemoryStream ms) { if (CaptureStream != null) CaptureStream(ms); } private void OnCaptureStringInternal(MemoryStream ms) { if (CaptureString != null) { string content = HttpContext.Current.Response.ContentEncoding.GetString(ms.ToArray()); OnCaptureString(content); } } protected virtual void OnCaptureString(string output) { if (CaptureString != null) CaptureString(output); } protected virtual byte[] OnTransformWrite(byte[] buffer) { if (TransformWrite != null) return TransformWrite(buffer); return buffer; } private byte[] OnTransformWriteStringInternal(byte[] buffer) { Encoding encoding = HttpContext.Current.Response.ContentEncoding; string output = OnTransformWriteString(encoding.GetString(buffer)); return encoding.GetBytes(output); } private string OnTransformWriteString(string value) { if (TransformWriteString != null) return TransformWriteString(value); return value; } protected virtual MemoryStream OnTransformCompleteStream(MemoryStream ms) { if (TransformStream != null) return TransformStream(ms); return ms; } /// <summary> /// Allows transforming of strings /// /// Note this handler is internal and not meant to be overridden /// as the TransformString Event has to be hooked up in order /// for this handler to even fire to avoid the overhead of string /// conversion on every pass through. /// </summary> /// <param name="responseText"></param> /// <returns></returns> private string OnTransformCompleteString(string responseText) { if (TransformString != null) TransformString(responseText); return responseText; } /// <summary> /// Wrapper method form OnTransformString that handles /// stream to string and vice versa conversions /// </summary> /// <param name="ms"></param> /// <returns></returns> internal MemoryStream OnTransformCompleteStringInternal(MemoryStream ms) { if (TransformString == null) return ms; //string content = ms.GetAsString(); string content = HttpContext.Current.Response.ContentEncoding.GetString(ms.ToArray()); content = TransformString(content); byte[] buffer = HttpContext.Current.Response.ContentEncoding.GetBytes(content); ms = new MemoryStream(); ms.Write(buffer, 0, buffer.Length); //ms.WriteString(content); return ms; } /// <summary> /// /// </summary> public override bool CanRead { get { return true; } } public override bool CanSeek { get { return true; } } /// <summary> /// /// </summary> public override bool CanWrite { get { return true; } } /// <summary> /// /// </summary> public override long Length { get { return 0; } } /// <summary> /// /// </summary> public override long Position { get { return _position; } set { _position = value; } } /// <summary> /// /// </summary> /// <param name="offset"></param> /// <param name="direction"></param> /// <returns></returns> public override long Seek(long offset, System.IO.SeekOrigin direction) { return _stream.Seek(offset, direction); } /// <summary> /// /// </summary> /// <param name="length"></param> public override void SetLength(long length) { _stream.SetLength(length); } /// <summary> /// /// </summary> public override void Close() { _stream.Close(); } /// <summary> /// Override flush by writing out the cached stream data /// </summary> public override void Flush() { if (IsCaptured && _cacheStream.Length > 0) { // Check for transform implementations _cacheStream = OnTransformCompleteStream(_cacheStream); _cacheStream = OnTransformCompleteStringInternal(_cacheStream); OnCaptureStream(_cacheStream); OnCaptureStringInternal(_cacheStream); // write the stream back out if output was delayed if (IsOutputDelayed) _stream.Write(_cacheStream.ToArray(), 0, (int)_cacheStream.Length); // Clear the cache once we've written it out _cacheStream.SetLength(0); } // default flush behavior _stream.Flush(); } /// <summary> /// /// </summary> /// <param name="buffer"></param> /// <param name="offset"></param> /// <param name="count"></param> /// <returns></returns> public override int Read(byte[] buffer, int offset, int count) { return _stream.Read(buffer, offset, count); } /// <summary> /// Overriden to capture output written by ASP.NET and captured /// into a cached stream that is written out later when Flush() /// is called. /// </summary> /// <param name="buffer"></param> /// <param name="offset"></param> /// <param name="count"></param> public override void Write(byte[] buffer, int offset, int count) { if ( IsCaptured ) { // copy to holding buffer only - we'll write out later _cacheStream.Write(buffer, 0, count); _cachePointer += count; } // just transform this buffer if (TransformWrite != null) buffer = OnTransformWrite(buffer); if (TransformWriteString != null) buffer = OnTransformWriteStringInternal(buffer); if (!IsOutputDelayed) _stream.Write(buffer, offset, buffer.Length); } } The key features are the events and corresponding OnXXX methods that handle the event hookups, and the Write() and Flush() methods of the stream implementation. All the rest of the members tend to be plain jane passthrough stream implementation code without much consequence. I do love the way Action<t> and Func<T> make it so easy to create the event signatures for the various events – sweet. A few Things to consider Performance Response.Filter is not great for performance in general as it adds another layer of indirection to the ASP.NET output pipeline, and this implementation in particular adds a memory hit as it basically duplicates the response output into the cached memory stream which is necessary since you may have to look at the entire response. If you have large pages in particular this can cause potentially serious memory pressure in your server application. So be careful of wholesale adoption of this (or other) Response.Filters. Make sure to do some performance testing to ensure it’s not killing your app’s performance. Response.Filter works everywhere A few questions came up in comments and discussion as to capturing ALL output hitting the site and – yes you can definitely do that by assigning a Response.Filter inside of a module. If you do this however you’ll want to be very careful and decide which content you actually want to capture especially in IIS 7 which passes ALL content – including static images/CSS etc. through the ASP.NET pipeline. So it is important to filter only on what you’re looking for – like the page extension or maybe more effectively the Response.ContentType. Response.Filter Chaining Originally I thought that filter chaining doesn’t work at all due to a bug in the stream implementation code. But it’s quite possible to assign multiple filters to the Response.Filter property. So the following actually works to both compress the output and apply the transformed content: WebUtils.GZipEncodePage(); ResponseFilterStream filter = new ResponseFilterStream(Response.Filter); filter.TransformString += filter_TransformString; Response.Filter = filter; However the following does not work resulting in invalid content encoding errors: ResponseFilterStream filter = new ResponseFilterStream(Response.Filter); filter.TransformString += filter_TransformString; Response.Filter = filter; WebUtils.GZipEncodePage(); In other words multiple Response filters can work together but it depends entirely on the implementation whether they can be chained or in which order they can be chained. In this case running the GZip/Deflate stream filters apparently relies on the original content length of the output and chokes when the content is modified. But if attaching the compression first it works fine as unintuitive as that may seem. Resources Download example code Capture Output from ASP.NET Pages © Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET  

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• SQL Server 2012 - AlwaysOn

  - by Claus Jandausch

  Ich war nicht nur irritiert, ich war sogar regelrecht schockiert - und für einen kurzen Moment sprachlos (was nur selten der Fall ist). Gerade eben hatte mich jemand gefragt "Wann Oracle denn etwas Vergleichbares wie AlwaysOn bieten würde - und ob überhaupt?" War ich hier im falschen Film gelandet? Ich konnte nicht anders, als meinen Unmut kundzutun und zu erklären, dass die Fragestellung normalerweise anders herum läuft. Zugegeben - es mag vielleicht strittige Punkte geben im Vergleich zwischen Oracle und SQL Server - bei denen nicht unbedingt immer Oracle die Nase vorn haben muss - aber das Thema Clustering für Hochverfügbarkeit (HA), Disaster Recovery (DR) und Skalierbarkeit gehört mit Sicherheit nicht dazu. Dieses Erlebnis hakte ich am Nachgang als Einzelfall ab, der so nie wieder vorkommen würde. Bis ich kurz darauf eines Besseren belehrt wurde und genau die selbe Frage erneut zu hören bekam. Diesmal sogar im Exadata-Umfeld und einem Oracle Stretch Cluster. Einmal ist keinmal, doch zweimal ist einmal zu viel... Getreu diesem alten Motto war mir klar, dass man das so nicht länger stehen lassen konnte. Ich habe keine Ahnung, wie die Microsoft Marketing Abteilung es geschafft hat, unter dem AlwaysOn Brading eine innovative Technologie vermuten zu lassen - aber sie hat ihren Job scheinbar gut gemacht. Doch abgesehen von einem guten Marketing, stellt sich natürlich die Frage, was wirklich dahinter steckt und wie sich das Ganze mit Oracle vergleichen lässt - und ob überhaupt? Damit wären wir wieder bei der ursprünglichen Frage angelangt.  So viel zum Hintergrund dieses Blogbeitrags - von meiner Antwort handelt der restliche Blog. "Windows was the God ..." Um den wahren Unterschied zwischen Oracle und Microsoft verstehen zu können, muss man zunächst das bedeutendste Microsoft Dogma kennen. Es lässt sich schlicht und einfach auf den Punkt bringen: "Alles muss auf Windows basieren." Die Überschrift dieses Absatzes ist kein von mir erfundener Ausspruch, sondern ein Zitat. Konkret stammt es aus einem längeren Artikel von Kurt Eichenwald in der Vanity Fair aus dem August 2012. Er lautet Microsoft's Lost Decade und sei jedem ans Herz gelegt, der die "Microsoft-Maschinerie" unter Steve Ballmer und einige ihrer Kuriositäten besser verstehen möchte. "YOU TALKING TO ME?" Microsoft C.E.O. Steve Ballmer bei seiner Keynote auf der 2012 International Consumer Electronics Show in Las Vegas am 9. Januar   Manche Dinge in diesem Artikel mögen überspitzt dargestellt erscheinen - sind sie aber nicht. Vieles davon kannte ich bereits aus eigener Erfahrung und kann es nur bestätigen. Anderes hat sich mir erst so richtig erschlossen. Insbesondere die folgenden Passagen führten zum Aha-Erlebnis: “Windows was the god—everything had to work with Windows,” said Stone... “Every little thing you want to write has to build off of Windows (or other existing roducts),” one software engineer said. “It can be very confusing, …” Ich habe immer schon darauf hingewiesen, dass in einem SQL Server Failover Cluster die Microsoft Datenbank eigentlich nichts Nenneswertes zum Geschehen beiträgt, sondern sich voll und ganz auf das Windows Betriebssystem verlässt. Deshalb muss man auch die Windows Server Enterprise Edition installieren, soll ein Failover Cluster für den SQL Server eingerichtet werden. Denn hier werden die Cluster Services geliefert - nicht mit dem SQL Server. Er ist nur lediglich ein weiteres Server Produkt, für das Windows in Ausfallszenarien genutzt werden kann - so wie Microsoft Exchange beispielsweise, oder Microsoft SharePoint, oder irgendein anderes Server Produkt das auf Windows gehostet wird. Auch Oracle kann damit genutzt werden. Das Stichwort lautet hier: Oracle Failsafe. Nur - warum sollte man das tun, wenn gleichzeitig eine überlegene Technologie wie die Oracle Real Application Clusters (RAC) zur Verfügung steht, die dann auch keine Windows Enterprise Edition voraussetzen, da Oracle die eigene Clusterware liefert. Welche darüber hinaus für kürzere Failover-Zeiten sorgt, da diese Cluster-Technologie Datenbank-integriert ist und sich nicht auf "Dritte" verlässt. Wenn man sich also schon keine technischen Vorteile mit einem SQL Server Failover Cluster erkauft, sondern zusätzlich noch versteckte Lizenzkosten durch die Lizenzierung der Windows Server Enterprise Edition einhandelt, warum hat Microsoft dann in den vergangenen Jahren seit SQL Server 2000 nicht ebenfalls an einer neuen und innovativen Lösung gearbeitet, die mit Oracle RAC mithalten kann? Entwickler hat Microsoft genügend? Am Geld kann es auch nicht liegen? Lesen Sie einfach noch einmal die beiden obenstehenden Zitate und sie werden den Grund verstehen. Anders lässt es sich ja auch gar nicht mehr erklären, dass AlwaysOn aus zwei unterschiedlichen Technologien besteht, die beide jedoch wiederum auf dem Windows Server Failover Clustering (WSFC) basieren. Denn daraus ergeben sich klare Nachteile - aber dazu später mehr. Um AlwaysOn zu verstehen, sollte man sich zunächst kurz in Erinnerung rufen, was Microsoft bisher an HA/DR (High Availability/Desaster Recovery) Lösungen für SQL Server zur Verfügung gestellt hat. Replikation Basiert auf logischer Replikation und Pubisher/Subscriber Architektur Transactional Replication Merge Replication Snapshot Replication Microsoft's Replikation ist vergleichbar mit Oracle GoldenGate. Oracle GoldenGate stellt jedoch die umfassendere Technologie dar und bietet High Performance. Log Shipping Microsoft's Log Shipping stellt eine einfache Technologie dar, die vergleichbar ist mit Oracle Managed Recovery in Oracle Version 7. Das Log Shipping besitzt folgende Merkmale: Transaction Log Backups werden von Primary nach Secondary/ies geschickt Einarbeitung (z.B. Restore) auf jedem Secondary individuell Optionale dritte Server Instanz (Monitor Server) für Überwachung und Alarm Log Restore Unterbrechung möglich für Read-Only Modus (Secondary) Keine Unterstützung von Automatic Failover Database Mirroring Microsoft's Database Mirroring wurde verfügbar mit SQL Server 2005, sah aus wie Oracle Data Guard in Oracle 9i, war funktional jedoch nicht so umfassend. Für ein HA/DR Paar besteht eine 1:1 Beziehung, um die produktive Datenbank (Principle DB) abzusichern. Auf der Standby Datenbank (Mirrored DB) werden alle Insert-, Update- und Delete-Operationen nachgezogen. Modi Synchron (High-Safety Modus) Asynchron (High-Performance Modus) Automatic Failover Unterstützt im High-Safety Modus (synchron) Witness Server vorausgesetzt     Zur Frage der Kontinuität Es stellt sich die Frage, wie es um diesen Technologien nun im Zusammenhang mit SQL Server 2012 bestellt ist. Unter Fanfaren seinerzeit eingeführt, war Database Mirroring das erklärte Mittel der Wahl. Ich bin kein Produkt Manager bei Microsoft und kann hierzu nur meine Meinung äußern, aber zieht man den SQL AlwaysOn Team Blog heran, so sieht es nicht gut aus für das Database Mirroring - zumindest nicht langfristig. "Does AlwaysOn Availability Group replace Database Mirroring going forward?” “The short answer is we recommend that you migrate from the mirroring configuration or even mirroring and log shipping configuration to using Availability Group. Database Mirroring will still be available in the Denali release but will be phased out over subsequent releases. Log Shipping will continue to be available in future releases.” Damit wären wir endlich beim eigentlichen Thema angelangt. Was ist eine sogenannte Availability Group und was genau hat es mit der vielversprechend klingenden Bezeichnung AlwaysOn auf sich?   SQL Server 2012 - AlwaysOn Zwei HA-Features verstekcne sich hinter dem “AlwaysOn”-Branding. Einmal das AlwaysOn Failover Clustering aka SQL Server Failover Cluster Instances (FCI) - zum Anderen die AlwaysOn Availability Groups. Failover Cluster Instances (FCI) Entspricht ungefähr dem Stretch Cluster Konzept von Oracle Setzt auf Windows Server Failover Clustering (WSFC) auf Bietet HA auf Instanz-Ebene AlwaysOn Availability Groups (Verfügbarkeitsgruppen) Ähnlich der Idee von Consistency Groups, wie in Storage-Level Replikations-Software von z.B. EMC SRDF Abhängigkeiten zu Windows Server Failover Clustering (WSFC) Bietet HA auf Datenbank-Ebene   Hinweis: Verwechseln Sie nicht eine SQL Server Datenbank mit einer Oracle Datenbank. Und auch nicht eine Oracle Instanz mit einer SQL Server Instanz. Die gleichen Begriffe haben hier eine andere Bedeutung - nicht selten ein Grund, weshalb Oracle- und Microsoft DBAs schnell aneinander vorbei reden. Denken Sie bei einer SQL Server Datenbank eher an ein Oracle Schema, das kommt der Sache näher. So etwas wie die SQL Server Northwind Datenbank ist vergleichbar mit dem Oracle Scott Schema. Wenn Sie die genauen Unterschiede kennen möchten, finden Sie eine detaillierte Beschreibung in meinem Buch "Oracle10g Release 2 für Windows und .NET", erhältich bei Lehmanns, Amazon, etc.   Windows Server Failover Clustering (WSFC) Wie man sieht, basieren beide AlwaysOn Technologien wiederum auf dem Windows Server Failover Clustering (WSFC), um einerseits Hochverfügbarkeit auf Ebene der Instanz zu gewährleisten und andererseits auf der Datenbank-Ebene. Deshalb nun eine kurze Beschreibung der WSFC. Die WSFC sind ein mit dem Windows Betriebssystem geliefertes Infrastruktur-Feature, um HA für Server Anwendungen, wie Microsoft Exchange, SharePoint, SQL Server, etc. zu bieten. So wie jeder andere Cluster, besteht ein WSFC Cluster aus einer Gruppe unabhängiger Server, die zusammenarbeiten, um die Verfügbarkeit einer Applikation oder eines Service zu erhöhen. Falls ein Cluster-Knoten oder -Service ausfällt, kann der auf diesem Knoten bisher gehostete Service automatisch oder manuell auf einen anderen im Cluster verfügbaren Knoten transferriert werden - was allgemein als Failover bekannt ist. Unter SQL Server 2012 verwenden sowohl die AlwaysOn Avalability Groups, als auch die AlwaysOn Failover Cluster Instances die WSFC als Plattformtechnologie, um Komponenten als WSFC Cluster-Ressourcen zu registrieren. Verwandte Ressourcen werden in eine Ressource Group zusammengefasst, die in Abhängigkeit zu anderen WSFC Cluster-Ressourcen gebracht werden kann. Der WSFC Cluster Service kann jetzt die Notwendigkeit zum Neustart der SQL Server Instanz erfassen oder einen automatischen Failover zu einem anderen Server-Knoten im WSFC Cluster auslösen.   Failover Cluster Instances (FCI) Eine SQL Server Failover Cluster Instanz (FCI) ist eine einzelne SQL Server Instanz, die in einem Failover Cluster betrieben wird, der aus mehreren Windows Server Failover Clustering (WSFC) Knoten besteht und so HA (High Availability) auf Ebene der Instanz bietet. Unter Verwendung von Multi-Subnet FCI kann auch Remote DR (Disaster Recovery) unterstützt werden. Eine weitere Option für Remote DR besteht darin, eine unter FCI gehostete Datenbank in einer Availability Group zu betreiben. Hierzu später mehr. FCI und WSFC Basis FCI, das für lokale Hochverfügbarkeit der Instanzen genutzt wird, ähnelt der veralteten Architektur eines kalten Cluster (Aktiv-Passiv). Unter SQL Server 2008 wurde diese Technologie SQL Server 2008 Failover Clustering genannt. Sie nutzte den Windows Server Failover Cluster. In SQL Server 2012 hat Microsoft diese Basistechnologie unter der Bezeichnung AlwaysOn zusammengefasst. Es handelt sich aber nach wie vor um die klassische Aktiv-Passiv-Konfiguration. Der Ablauf im Failover-Fall ist wie folgt: Solange kein Hardware-oder System-Fehler auftritt, werden alle Dirty Pages im Buffer Cache auf Platte geschrieben Alle entsprechenden SQL Server Services (Dienste) in der Ressource Gruppe werden auf dem aktiven Knoten gestoppt Die Ownership der Ressource Gruppe wird auf einen anderen Knoten der FCI transferriert Der neue Owner (Besitzer) der Ressource Gruppe startet seine SQL Server Services (Dienste) Die Connection-Anforderungen einer Client-Applikation werden automatisch auf den neuen aktiven Knoten mit dem selben Virtuellen Network Namen (VNN) umgeleitet Abhängig vom Zeitpunkt des letzten Checkpoints, kann die Anzahl der Dirty Pages im Buffer Cache, die noch auf Platte geschrieben werden müssen, zu unvorhersehbar langen Failover-Zeiten führen. Um diese Anzahl zu drosseln, besitzt der SQL Server 2012 eine neue Fähigkeit, die Indirect Checkpoints genannt wird. Indirect Checkpoints ähnelt dem Fast-Start MTTR Target Feature der Oracle Datenbank, das bereits mit Oracle9i verfügbar war.   SQL Server Multi-Subnet Clustering Ein SQL Server Multi-Subnet Failover Cluster entspricht vom Konzept her einem Oracle RAC Stretch Cluster. Doch dies ist nur auf den ersten Blick der Fall. Im Gegensatz zu RAC ist in einem lokalen SQL Server Failover Cluster jeweils nur ein Knoten aktiv für eine Datenbank. Für die Datenreplikation zwischen geografisch entfernten Sites verlässt sich Microsoft auf 3rd Party Lösungen für das Storage Mirroring.     Die Verbesserung dieses Szenario mit einer SQL Server 2012 Implementierung besteht schlicht darin, dass eine VLAN-Konfiguration (Virtual Local Area Network) nun nicht mehr benötigt wird, so wie dies bisher der Fall war. Das folgende Diagramm stellt dar, wie der Ablauf mit SQL Server 2012 gehandhabt wird. In Site A und Site B wird HA jeweils durch einen lokalen Aktiv-Passiv-Cluster sichergestellt.     Besondere Aufmerksamkeit muss hier der Konfiguration und dem Tuning geschenkt werden, da ansonsten völlig inakzeptable Failover-Zeiten resultieren. Dies liegt darin begründet, weil die Downtime auf Client-Seite nun nicht mehr nur von der reinen Failover-Zeit abhängt, sondern zusätzlich von der Dauer der DNS Replikation zwischen den DNS Servern. (Rufen Sie sich in Erinnerung, dass wir gerade von Multi-Subnet Clustering sprechen). Außerdem ist zu berücksichtigen, wie schnell die Clients die aktualisierten DNS Informationen abfragen. Spezielle Konfigurationen für Node Heartbeat, HostRecordTTL (Host Record Time-to-Live) und Intersite Replication Frequeny für Active Directory Sites und Services werden notwendig. Default TTL für Windows Server 2008 R2: 20 Minuten Empfohlene Einstellung: 1 Minute DNS Update Replication Frequency in Windows Umgebung: 180 Minuten Empfohlene Einstellung: 15 Minuten (minimaler Wert)   Betrachtet man diese Werte, muss man feststellen, dass selbst eine optimale Konfiguration die rigiden SLAs (Service Level Agreements) heutiger geschäftskritischer Anwendungen für HA und DR nicht erfüllen kann. Denn dies impliziert eine auf der Client-Seite erlebte Failover-Zeit von insgesamt 16 Minuten. Hierzu ein Auszug aus der SQL Server 2012 Online Dokumentation: Cons: If a cross-subnet failover occurs, the client recovery time could be 15 minutes or longer, depending on your HostRecordTTL setting and the setting of your cross-site DNS/AD replication schedule.    Wir sind hier an einem Punkt unserer Überlegungen angelangt, an dem sich erklärt, weshalb ich zuvor das "Windows was the God ..." Zitat verwendet habe. Die unbedingte Abhängigkeit zu Windows wird zunehmend zum Problem, da sie die Komplexität einer Microsoft-basierenden Lösung erhöht, anstelle sie zu reduzieren. Und Komplexität ist das Letzte, was sich CIOs heutzutage wünschen.  Zur Ehrenrettung des SQL Server 2012 und AlwaysOn muss man sagen, dass derart lange Failover-Zeiten kein unbedingtes "Muss" darstellen, sondern ein "Kann". Doch auch ein "Kann" kann im unpassenden Moment unvorhersehbare und kostspielige Folgen haben. Die Unabsehbarkeit ist wiederum Ursache vieler an der Implementierung beteiligten Komponenten und deren Abhängigkeiten, wie beispielsweise drei Cluster-Lösungen (zwei von Microsoft, eine 3rd Party Lösung). Wie man die Sache auch dreht und wendet, kommt man an diesem Fakt also nicht vorbei - ganz unabhängig von der Dauer einer Downtime oder Failover-Zeiten. Im Gegensatz zu AlwaysOn und der hier vorgestellten Version eines Stretch-Clusters, vermeidet eine entsprechende Oracle Implementierung eine derartige Komplexität, hervorgerufen duch multiple Abhängigkeiten. Den Unterschied machen Datenbank-integrierte Mechanismen, wie Fast Application Notification (FAN) und Fast Connection Failover (FCF). Für Oracle MAA Konfigurationen (Maximum Availability Architecture) sind Inter-Site Failover-Zeiten im Bereich von Sekunden keine Seltenheit. Wenn Sie dem Link zur Oracle MAA folgen, finden Sie außerdem eine Reihe an Customer Case Studies. Auch dies ist ein wichtiges Unterscheidungsmerkmal zu AlwaysOn, denn die Oracle Technologie hat sich bereits zigfach in höchst kritischen Umgebungen bewährt.   Availability Groups (Verfügbarkeitsgruppen) Die sogenannten Availability Groups (Verfügbarkeitsgruppen) sind - neben FCI - der weitere Baustein von AlwaysOn.   Hinweis: Bevor wir uns näher damit beschäftigen, sollten Sie sich noch einmal ins Gedächtnis rufen, dass eine SQL Server Datenbank nicht die gleiche Bedeutung besitzt, wie eine Oracle Datenbank, sondern eher einem Oracle Schema entspricht. So etwas wie die SQL Server Northwind Datenbank ist vergleichbar mit dem Oracle Scott Schema.   Eine Verfügbarkeitsgruppe setzt sich zusammen aus einem Set mehrerer Benutzer-Datenbanken, die im Falle eines Failover gemeinsam als Gruppe behandelt werden. Eine Verfügbarkeitsgruppe unterstützt ein Set an primären Datenbanken (primäres Replikat) und einem bis vier Sets von entsprechenden sekundären Datenbanken (sekundäre Replikate).       Es können jedoch nicht alle SQL Server Datenbanken einer AlwaysOn Verfügbarkeitsgruppe zugeordnet werden. Der SQL Server Spezialist Michael Otey zählt in seinem SQL Server Pro Artikel folgende Anforderungen auf: Verfügbarkeitsgruppen müssen mit Benutzer-Datenbanken erstellt werden. System-Datenbanken können nicht verwendet werden Die Datenbanken müssen sich im Read-Write Modus befinden. Read-Only Datenbanken werden nicht unterstützt Die Datenbanken in einer Verfügbarkeitsgruppe müssen Multiuser Datenbanken sein Sie dürfen nicht das AUTO_CLOSE Feature verwenden Sie müssen das Full Recovery Modell nutzen und es muss ein vollständiges Backup vorhanden sein Eine gegebene Datenbank kann sich nur in einer einzigen Verfügbarkeitsgruppe befinden und diese Datenbank düerfen nicht für Database Mirroring konfiguriert sein Microsoft empfiehl außerdem, dass der Verzeichnispfad einer Datenbank auf dem primären und sekundären Server identisch sein sollte Wie man sieht, eignen sich Verfügbarkeitsgruppen nicht, um HA und DR vollständig abzubilden. Die Unterscheidung zwischen der Instanzen-Ebene (FCI) und Datenbank-Ebene (Availability Groups) ist von hoher Bedeutung. Vor kurzem wurde mir gesagt, dass man mit den Verfügbarkeitsgruppen auf Shared Storage verzichten könne und dadurch Kosten spart. So weit so gut ... Man kann natürlich eine Installation rein mit Verfügbarkeitsgruppen und ohne FCI durchführen - aber man sollte sich dann darüber bewusst sein, was man dadurch alles nicht abgesichert hat - und dies wiederum für Desaster Recovery (DR) und SLAs (Service Level Agreements) bedeutet. Kurzum, um die Kombination aus beiden AlwaysOn Produkten und der damit verbundene Komplexität kommt man wohl in der Praxis nicht herum.    Availability Groups und WSFC AlwaysOn hängt von Windows Server Failover Clustering (WSFC) ab, um die aktuellen Rollen der Verfügbarkeitsreplikate einer Verfügbarkeitsgruppe zu überwachen und zu verwalten, und darüber zu entscheiden, wie ein Failover-Ereignis die Verfügbarkeitsreplikate betrifft. Das folgende Diagramm zeigt de Beziehung zwischen Verfügbarkeitsgruppen und WSFC:   Der Verfügbarkeitsmodus ist eine Eigenschaft jedes Verfügbarkeitsreplikats. Synychron und Asynchron können also gemischt werden: Availability Modus (Verfügbarkeitsmodus) Asynchroner Commit-Modus Primäres replikat schließt Transaktionen ohne Warten auf Sekundäres Synchroner Commit-Modus Primäres Replikat wartet auf Commit von sekundärem Replikat Failover Typen Automatic Manual Forced (mit möglichem Datenverlust) Synchroner Commit-Modus Geplanter, manueller Failover ohne Datenverlust Automatischer Failover ohne Datenverlust Asynchroner Commit-Modus Nur Forced, manueller Failover mit möglichem Datenverlust   Der SQL Server kennt keinen separaten Switchover Begriff wie in Oracle Data Guard. Für SQL Server werden alle Role Transitions als Failover bezeichnet. Tatsächlich unterstützt der SQL Server keinen Switchover für asynchrone Verbindungen. Es gibt nur die Form des Forced Failover mit möglichem Datenverlust. Eine ähnliche Fähigkeit wie der Switchover unter Oracle Data Guard ist so nicht gegeben.   SQL Sever FCI mit Availability Groups (Verfügbarkeitsgruppen) Neben den Verfügbarkeitsgruppen kann eine zweite Failover-Ebene eingerichtet werden, indem SQL Server FCI (auf Shared Storage) mit WSFC implementiert wird. Ein Verfügbarkeitesreplikat kann dann auf einer Standalone Instanz gehostet werden, oder einer FCI Instanz. Zum Verständnis: Die Verfügbarkeitsgruppen selbst benötigen kein Shared Storage. Diese Kombination kann verwendet werden für lokale HA auf Ebene der Instanz und DR auf Datenbank-Ebene durch Verfügbarkeitsgruppen. Das folgende Diagramm zeigt dieses Szenario:   Achtung! Hier handelt es sich nicht um ein Pendant zu Oracle RAC plus Data Guard, auch wenn das Bild diesen Eindruck vielleicht vermitteln mag - denn alle sekundären Knoten im FCI sind rein passiv. Es existiert außerdem eine weitere und ernsthafte Einschränkung: SQL Server Failover Cluster Instanzen (FCI) unterstützen nicht das automatische AlwaysOn Failover für Verfügbarkeitsgruppen. Jedes unter FCI gehostete Verfügbarkeitsreplikat kann nur für manuelles Failover konfiguriert werden.   Lesbare Sekundäre Replikate Ein oder mehrere Verfügbarkeitsreplikate in einer Verfügbarkeitsgruppe können für den lesenden Zugriff konfiguriert werden, wenn sie als sekundäres Replikat laufen. Dies ähnelt Oracle Active Data Guard, jedoch gibt es Einschränkungen. Alle Abfragen gegen die sekundäre Datenbank werden automatisch auf das Snapshot Isolation Level abgebildet. Es handelt sich dabei um eine Versionierung der Rows. Microsoft versuchte hiermit die Oracle MVRC (Multi Version Read Consistency) nachzustellen. Tatsächlich muss man die SQL Server Snapshot Isolation eher mit Oracle Flashback vergleichen. Bei der Implementierung des Snapshot Isolation Levels handelt sich um ein nachträglich aufgesetztes Feature und nicht um einen inhärenten Teil des Datenbank-Kernels, wie im Falle Oracle. (Ich werde hierzu in Kürze einen weiteren Blogbeitrag verfassen, wenn ich mich mit der neuen SQL Server 2012 Core Lizenzierung beschäftige.) Für die Praxis entstehen aus der Abbildung auf das Snapshot Isolation Level ernsthafte Restriktionen, derer man sich für den Betrieb in der Praxis bereits vorab bewusst sein sollte: Sollte auf der primären Datenbank eine aktive Transaktion zu dem Zeitpunkt existieren, wenn ein lesbares sekundäres Replikat in die Verfügbarkeitsgruppe aufgenommen wird, werden die Row-Versionen auf der korrespondierenden sekundären Datenbank nicht sofort vollständig verfügbar sein. Eine aktive Transaktion auf dem primären Replikat muss zuerst abgeschlossen (Commit oder Rollback) und dieser Transaktions-Record auf dem sekundären Replikat verarbeitet werden. Bis dahin ist das Isolation Level Mapping auf der sekundären Datenbank unvollständig und Abfragen sind temporär geblockt. Microsoft sagt dazu: "This is needed to guarantee that row versions are available on the secondary replica before executing the query under snapshot isolation as all isolation levels are implicitly mapped to snapshot isolation." (SQL Storage Engine Blog: AlwaysOn: I just enabled Readable Secondary but my query is blocked?)  Grundlegend bedeutet dies, dass ein aktives lesbares Replikat nicht in die Verfügbarkeitsgruppe aufgenommen werden kann, ohne das primäre Replikat vorübergehend stillzulegen. Da Leseoperationen auf das Snapshot Isolation Transaction Level abgebildet werden, kann die Bereinigung von Ghost Records auf dem primären Replikat durch Transaktionen auf einem oder mehreren sekundären Replikaten geblockt werden - z.B. durch eine lang laufende Abfrage auf dem sekundären Replikat. Diese Bereinigung wird auch blockiert, wenn die Verbindung zum sekundären Replikat abbricht oder der Datenaustausch unterbrochen wird. Auch die Log Truncation wird in diesem Zustant verhindert. Wenn dieser Zustand längere Zeit anhält, empfiehlt Microsoft das sekundäre Replikat aus der Verfügbarkeitsgruppe herauszunehmen - was ein ernsthaftes Downtime-Problem darstellt. Die Read-Only Workload auf den sekundären Replikaten kann eingehende DDL Änderungen blockieren. Obwohl die Leseoperationen aufgrund der Row-Versionierung keine Shared Locks halten, führen diese Operatioen zu Sch-S Locks (Schemastabilitätssperren). DDL-Änderungen durch Redo-Operationen können dadurch blockiert werden. Falls DDL aufgrund konkurrierender Lese-Workload blockiert wird und der Schwellenwert für 'Recovery Interval' (eine SQL Server Konfigurationsoption) überschritten wird, generiert der SQL Server das Ereignis sqlserver.lock_redo_blocked, welches Microsoft zum Kill der blockierenden Leser empfiehlt. Auf die Verfügbarkeit der Anwendung wird hierbei keinerlei Rücksicht genommen.   Keine dieser Einschränkungen existiert mit Oracle Active Data Guard.   Backups auf sekundären Replikaten  Über die sekundären Replikate können Backups (BACKUP DATABASE via Transact-SQL) nur als copy-only Backups einer vollständigen Datenbank, Dateien und Dateigruppen erstellt werden. Das Erstellen inkrementeller Backups ist nicht unterstützt, was ein ernsthafter Rückstand ist gegenüber der Backup-Unterstützung physikalischer Standbys unter Oracle Data Guard. Hinweis: Ein möglicher Workaround via Snapshots, bleibt ein Workaround. Eine weitere Einschränkung dieses Features gegenüber Oracle Data Guard besteht darin, dass das Backup eines sekundären Replikats nicht ausgeführt werden kann, wenn es nicht mit dem primären Replikat kommunizieren kann. Darüber hinaus muss das sekundäre Replikat synchronisiert sein oder sich in der Synchronisation befinden, um das Beackup auf dem sekundären Replikat erstellen zu können.   Vergleich von Microsoft AlwaysOn mit der Oracle MAA Ich komme wieder zurück auf die Eingangs erwähnte, mehrfach an mich gestellte Frage "Wann denn - und ob überhaupt - Oracle etwas Vergleichbares wie AlwaysOn bieten würde?" und meine damit verbundene (kurze) Irritation. Wenn Sie diesen Blogbeitrag bis hierher gelesen haben, dann kennen Sie jetzt meine darauf gegebene Antwort. Der eine oder andere Punkt traf dabei nicht immer auf Jeden zu, was auch nicht der tiefere Sinn und Zweck meiner Antwort war. Wenn beispielsweise kein Multi-Subnet mit im Spiel ist, sind alle diesbezüglichen Kritikpunkte zunächst obsolet. Was aber nicht bedeutet, dass sie nicht bereits morgen schon wieder zum Thema werden könnten (Sag niemals "Nie"). In manch anderes Fettnäpfchen tritt man wiederum nicht unbedingt in einer Testumgebung, sondern erst im laufenden Betrieb. Erst recht nicht dann, wenn man sich potenzieller Probleme nicht bewusst ist und keine dedizierten Tests startet. Und wer AlwaysOn erfolgreich positionieren möchte, wird auch gar kein Interesse daran haben, auf mögliche Schwachstellen und den besagten Teufel im Detail aufmerksam zu machen. Das ist keine Unterstellung - es ist nur menschlich. Außerdem ist es verständlich, dass man sich in erster Linie darauf konzentriert "was geht" und "was gut läuft", anstelle auf das "was zu Problemen führen kann" oder "nicht funktioniert". Wer will schon der Miesepeter sein? Für mich selbst gesprochen, kann ich nur sagen, dass ich lieber vorab von allen möglichen Einschränkungen wissen möchte, anstelle sie dann nach einer kurzen Zeit der heilen Welt schmerzhaft am eigenen Leib erfahren zu müssen. Ich bin davon überzeugt, dass es Ihnen nicht anders geht. Nachfolgend deshalb eine Zusammenfassung all jener Punkte, die ich im Vergleich zur Oracle MAA (Maximum Availability Architecture) als unbedingt Erwähnenswert betrachte, falls man eine Evaluierung von Microsoft AlwaysOn in Betracht zieht. 1. AlwaysOn ist eine komplexe Technologie Der SQL Server AlwaysOn Stack ist zusammengesetzt aus drei verschiedenen Technlogien: Windows Server Failover Clustering (WSFC) SQL Server Failover Cluster Instances (FCI) SQL Server Availability Groups (Verfügbarkeitsgruppen) Man kann eine derartige Lösung nicht als nahtlos bezeichnen, wofür auch die vielen von Microsoft dargestellten Einschränkungen sprechen. Während sich frühere SQL Server Versionen in Richtung eigener HA/DR Technologien entwickelten (wie Database Mirroring), empfiehlt Microsoft nun die Migration. Doch weshalb dieser Schwenk? Er führt nicht zu einem konsisten und robusten Angebot an HA/DR Technologie für geschäftskritische Umgebungen.  Liegt die Antwort in meiner These begründet, nach der "Windows was the God ..." noch immer gilt und man die Nachteile der allzu engen Kopplung mit Windows nicht sehen möchte? Entscheiden Sie selbst ... 2. Failover Cluster Instanzen - Kein RAC-Pendant Die SQL Server und Windows Server Clustering Technologie basiert noch immer auf dem veralteten Aktiv-Passiv Modell und führt zu einer Verschwendung von Systemressourcen. In einer Betrachtung von lediglich zwei Knoten erschließt sich auf Anhieb noch nicht der volle Mehrwert eines Aktiv-Aktiv Clusters (wie den Real Application Clusters), wie er von Oracle bereits vor zehn Jahren entwickelt wurde. Doch kennt man die Vorzüge der Skalierbarkeit durch einfaches Hinzufügen weiterer Cluster-Knoten, die dann alle gemeinsam als ein einziges logisches System zusammenarbeiten, versteht man was hinter dem Motto "Pay-as-you-Grow" steckt. In einem Aktiv-Aktiv Cluster geht es zwar auch um Hochverfügbarkeit - und ein Failover erfolgt zudem schneller, als in einem Aktiv-Passiv Modell - aber es geht eben nicht nur darum. An dieser Stelle sei darauf hingewiesen, dass die Oracle 11g Standard Edition bereits die Nutzung von Oracle RAC bis zu vier Sockets kostenfrei beinhaltet. Möchten Sie dazu Windows nutzen, benötigen Sie keine Windows Server Enterprise Edition, da Oracle 11g die eigene Clusterware liefert. Sie kommen in den Genuss von Hochverfügbarkeit und Skalierbarkeit und können dazu die günstigere Windows Server Standard Edition nutzen. 3. SQL Server Multi-Subnet Clustering - Abhängigkeit zu 3rd Party Storage Mirroring  Die SQL Server Multi-Subnet Clustering Architektur unterstützt den Aufbau eines Stretch Clusters, basiert dabei aber auf dem Aktiv-Passiv Modell. Das eigentlich Problematische ist jedoch, dass man sich zur Absicherung der Datenbank auf 3rd Party Storage Mirroring Technologie verlässt, ohne Integration zwischen dem Windows Server Failover Clustering (WSFC) und der darunterliegenden Mirroring Technologie. Wenn nun im Cluster ein Failover auf Instanzen-Ebene erfolgt, existiert keine Koordination mit einem möglichen Failover auf Ebene des Storage-Array. 4. Availability Groups (Verfügbarkeitsgruppen) - Vier, oder doch nur Zwei? Ein primäres Replikat erlaubt bis zu vier sekundäre Replikate innerhalb einer Verfügbarkeitsgruppe, jedoch nur zwei im Synchronen Commit Modus. Während dies zwar einen Vorteil gegenüber dem stringenten 1:1 Modell unter Database Mirroring darstellt, fällt der SQL Server 2012 damit immer noch weiter zurück hinter Oracle Data Guard mit bis zu 30 direkten Stanbdy Zielen - und vielen weiteren durch kaskadierende Ziele möglichen. Damit eignet sich Oracle Active Data Guard auch für die Bereitstellung einer Reader-Farm Skalierbarkeit für Internet-basierende Unternehmen. Mit AwaysOn Verfügbarkeitsgruppen ist dies nicht möglich. 5. Availability Groups (Verfügbarkeitsgruppen) - kein asynchrones Switchover  Die Technologie der Verfügbarkeitsgruppen wird auch als geeignetes Mittel für administrative Aufgaben positioniert - wie Upgrades oder Wartungsarbeiten. Man muss sich jedoch einem gravierendem Defizit bewusst sein: Im asynchronen Verfügbarkeitsmodus besteht die einzige Möglichkeit für Role Transition im Forced Failover mit Datenverlust! Um den Verlust von Daten durch geplante Wartungsarbeiten zu vermeiden, muss man den synchronen Verfügbarkeitsmodus konfigurieren, was jedoch ernstzunehmende Auswirkungen auf WAN Deployments nach sich zieht. Spinnt man diesen Gedanken zu Ende, kommt man zu dem Schluss, dass die Technologie der Verfügbarkeitsgruppen für geplante Wartungsarbeiten in einem derartigen Umfeld nicht effektiv genutzt werden kann. 6. Automatisches Failover - Nicht immer möglich Sowohl die SQL Server FCI, als auch Verfügbarkeitsgruppen unterstützen automatisches Failover. Möchte man diese jedoch kombinieren, wird das Ergebnis kein automatisches Failover sein. Denn ihr Zusammentreffen im Failover-Fall führt zu Race Conditions (Wettlaufsituationen), weshalb diese Konfiguration nicht länger das automatische Failover zu einem Replikat in einer Verfügbarkeitsgruppe erlaubt. Auch hier bestätigt sich wieder die tiefere Problematik von AlwaysOn, mit einer Zusammensetzung aus unterschiedlichen Technologien und der Abhängigkeit zu Windows. 7. Problematische RTO (Recovery Time Objective) Microsoft postioniert die SQL Server Multi-Subnet Clustering Architektur als brauchbare HA/DR Architektur. Bedenkt man jedoch die Problematik im Zusammenhang mit DNS Replikation und den möglichen langen Wartezeiten auf Client-Seite von bis zu 16 Minuten, sind strenge RTO Anforderungen (Recovery Time Objectives) nicht erfüllbar. Im Gegensatz zu Oracle besitzt der SQL Server keine Datenbank-integrierten Technologien, wie Oracle Fast Application Notification (FAN) oder Oracle Fast Connection Failover (FCF). 8. Problematische RPO (Recovery Point Objective) SQL Server ermöglicht Forced Failover (erzwungenes Failover), bietet jedoch keine Möglichkeit zur automatischen Übertragung der letzten Datenbits von einem alten zu einem neuen primären Replikat, wenn der Verfügbarkeitsmodus asynchron war. Oracle Data Guard hingegen bietet diese Unterstützung durch das Flush Redo Feature. Dies sichert "Zero Data Loss" und beste RPO auch in erzwungenen Failover-Situationen. 9. Lesbare Sekundäre Replikate mit Einschränkungen Aufgrund des Snapshot Isolation Transaction Level für lesbare sekundäre Replikate, besitzen diese Einschränkungen mit Auswirkung auf die primäre Datenbank. Die Bereinigung von Ghost Records auf der primären Datenbank, wird beeinflusst von lang laufenden Abfragen auf der lesabaren sekundären Datenbank. Die lesbare sekundäre Datenbank kann nicht in die Verfügbarkeitsgruppe aufgenommen werden, wenn es aktive Transaktionen auf der primären Datenbank gibt. Zusätzlich können DLL Änderungen auf der primären Datenbank durch Abfragen auf der sekundären blockiert werden. Und imkrementelle Backups werden hier nicht unterstützt.   Keine dieser Restriktionen existiert unter Oracle Data Guard.

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• WMI Rights required to read root\MicrosoftIISv2 in IIS7 with IIS6 compatibility mode

  - by JoeBilly

  I need to manage my IIS7 (Windows Server 2008) remotely with a WMI IIS6 API. So I added the IIS6 WMI Compatibility and IIS6 Metabase Compatibility roles to access the root\MicrosoftIIsv2 namespace. I have a domain account which is not administrator on the remote machine ; with this right, everything is ok. I configured these rights for my domain account to access the root\MicrosoftIIsv2 WMI namespace remotely ; note that these rights work perfectly on a IIS6 and Windows Server 2003 : DCOM : Account in Distributed COM Users Remote & local access to DCOM WMI : Root\CIMV2 (I need access here too) Execute methods, Enable Account, Remote Enable Root\Default (I need access here too) Execute methods, Enable Account, Remote Enable Root\MicrosoftIISv2 Execute methods, Enable Account, Provider Write, Remote Enable IIS Metabase (Metabase Explorer) : LM Full Control (W3SVC inherits these permissions) I tried to give some access on C:\Windows\System32\inetsrv too ; don't know if needed. My issue is : I can't list the IIS WebSites (\root\MicrosoftIISv2:IIsWebServerSetting.Name="W3SVC/*"). I don't get an 'access denied' but nothing is returned. My API and powershell tests can connect and execute queries in the root\MicrosoftIISv2 namespace I can read the IIsComputer class ex: Get-WmiObject IIsComputer -namespace "ROOT\MicrosoftIISv2" -authentication PacketPrivacy | SELECT * I can't read the IIsWebServerSetting, IIsWebServer ... to list the WebSites : the query returns an empty collection ex: Get-WmiObject IIsWebServerSetting -namespace "ROOT\MicrosoftIISv2" -authentication PacketPrivacy | SELECT ServerComment All queries work perfectly if the account is administrator as already said I am using PacketPrivacy authentication FI: I got a Warning Event 5605 with the Administrator right or not, that does not seem to have an impact : The root\MicrosoftIISv2 namespace is marked with the RequiresEncryption flag. Access to this namespace might be denied if the script or application does not have the appropriate authentication level. Change the authentication level to Pkt_Privacy and run the script or application again Ok, I have some more informations, when I use IIS 6 Metabase Explorer with my administrator account I can see the rights are correctly inherited for my non-administrator account. But when I try to connect using my non-administrator account, I can list the LM node, but get an "access denied, failed to get a key's data" when I try to browse the child nodes. I'll check further. I tried to Trace the WMI Activity, and everything seems OK ; this tends to confirm that the problem lies in IIS Rights.

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• Windows Server 2012 Branchcache vs. DFS-R

  - by TheCleaner

  Warning, subjective question ahead! But hopefully a good one that won't get closed. SCENARIO: I have a branch office that currently has no on-premise server. They access everything including a DC across a 12Mbps WAN link (MPLS). The link isn't saturated, averaging around 20% utilization. The circuit is very stable and has a high SLA and excellent uptime. However, large file transfers (mainly reads, not writes) from the file server across the WAN can be slow. We don't currently utilize DFS. RESEARCH DONE: I'm aware of WAN acceleration, using either dedicated hardware (Riverbed) or a dedicated software VM (Silver Peak) for example. But the pricing is outside of our current budget and the need isn't quite there yet from our perspective (since the issue is mainly in a "pull" scenario not necessarily push/pull). I'm mainly looking at deploying a Windows server at this branch office and either utilizing DFS-R or BranchCache. Looking at a table comparison and assuming we are looking at a "hosted branchcache server" and not simply distributed: It would appear there are benefits to both, even if both are "hosted" on a server. QUESTIONS I ACTUALLY HAVE: In what scenarios do each of these techs shine and where do you choose one over the other? Looking at a hosted Branchcache server, can you set "pre-fetching" of certain folders/files on the central file server so that they are immediately accessible locally at the branch? Do you have to do this on a schedule (if it is possible)? Looking at DFS-R my concern (and apparently solved with 3rd party apps) is file locking and making sure the file gets updated properly during a write operation (ie, making sure if both copies are accessed and both are written to, which file takes precedence and what happens to the changes?). Ideal it would seem would be to lock any alternate replicas of the data, but is it really that big of an issue? Does Branchcache lock the central file for editing? Does branchcache only transmit the deltas back to the central file of what has changed? Would either technology be ill advised if the branch office server was going to be utilized as a domain controller as well?

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• Ruby on Rails: url_for :back leads to NoMethodError for back_url

  - by Platinum Azure

  Hi all, I'm trying to use url_for(:back) to create a redirect leading back to a previous page upon a user's logging in. I've had it working successfully for when the user just goes to the login page on his or her own. However, when the user is redirected to the login page due to accessing a page requiring that the user be authenticated, the redirect sends the user back to the page before the one s/he had tried to access with insufficient permissions. I'm trying to modify my login controller action to deal with the redirect properly. My plan is to have a query string parameter "redirect" that is used when a forced redirect occurs. In the controller, if that parameter exists that URL is used; otherwise, url_for(:back) is used, or if that doesn't work (due to lack of HTTP_REFERER), then the user is redirected to the site's home page. Here is the code snippet which is supposed to implement this logic: if params[:redirect] @url = params[:redirect] else @url = url_for :back @url ||= url_for :controller => "home", :action => "index" end The error I get is: NoMethodError in UsersController#login undefined method `back_url' for # RAILS_ROOT: [obscured] Application Trace | Framework Trace | Full Trace vendor/rails/actionpack/lib/action_controller/polymorphic_routes.rb:112:in `__send__' vendor/rails/actionpack/lib/action_controller/polymorphic_routes.rb:112:in `polymorphic_url' vendor/rails/actionpack/lib/action_controller/base.rb:628:in `url_for' app/controllers/users_controller.rb:16:in `login' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/rails.rb:76:in `process' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/rails.rb:74:in `synchronize' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/rails.rb:74:in `process' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:159:in `process_client' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:158:in `each' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:158:in `process_client' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:285:in `run' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:285:in `initialize' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:285:in `new' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:285:in `run' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:268:in `initialize' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:268:in `new' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:268:in `run' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/configurator.rb:282:in `run' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/configurator.rb:281:in `each' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/configurator.rb:281:in `run' /var/lib/gems/1.8/gems/mongrel-1.1.5/bin/mongrel_rails:128:in `run' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/command.rb:212:in `run' /var/lib/gems/1.8/gems/mongrel-1.1.5/bin/mongrel_rails:281 vendor/rails/actionpack/lib/action_controller/polymorphic_routes.rb:112:in `__send__' vendor/rails/actionpack/lib/action_controller/polymorphic_routes.rb:112:in `polymorphic_url' vendor/rails/actionpack/lib/action_controller/base.rb:628:in `url_for' vendor/rails/actionpack/lib/action_controller/base.rb:1256:in `send' vendor/rails/actionpack/lib/action_controller/base.rb:1256:in `perform_action_without_filters' vendor/rails/actionpack/lib/action_controller/filters.rb:617:in `call_filters' vendor/rails/actionpack/lib/action_controller/filters.rb:610:in `perform_action_without_benchmark' vendor/rails/actionpack/lib/action_controller/benchmarking.rb:68:in `perform_action_without_rescue' /usr/lib/ruby/1.8/benchmark.rb:293:in `measure' vendor/rails/actionpack/lib/action_controller/benchmarking.rb:68:in `perform_action_without_rescue' vendor/rails/actionpack/lib/action_controller/rescue.rb:136:in `perform_action_without_caching' vendor/rails/actionpack/lib/action_controller/caching/sql_cache.rb:13:in `perform_action' vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb:34:in `cache' vendor/rails/activerecord/lib/active_record/query_cache.rb:8:in `cache' vendor/rails/actionpack/lib/action_controller/caching/sql_cache.rb:12:in `perform_action' vendor/rails/actionpack/lib/action_controller/base.rb:524:in `send' vendor/rails/actionpack/lib/action_controller/base.rb:524:in `process_without_filters' vendor/rails/actionpack/lib/action_controller/filters.rb:606:in `process_without_session_management_support' vendor/rails/actionpack/lib/action_controller/session_management.rb:134:in `process' vendor/rails/actionpack/lib/action_controller/base.rb:392:in `process' vendor/rails/actionpack/lib/action_controller/dispatcher.rb:184:in `handle_request' vendor/rails/actionpack/lib/action_controller/dispatcher.rb:112:in `dispatch_unlocked' vendor/rails/actionpack/lib/action_controller/dispatcher.rb:125:in `dispatch' vendor/rails/actionpack/lib/action_controller/dispatcher.rb:124:in `synchronize' vendor/rails/actionpack/lib/action_controller/dispatcher.rb:124:in `dispatch' vendor/rails/actionpack/lib/action_controller/dispatcher.rb:134:in `dispatch_cgi' vendor/rails/actionpack/lib/action_controller/dispatcher.rb:41:in `dispatch' vendor/rails/activesupport/lib/active_support/dependencies.rb:142:in `load_without_new_constant_marking' vendor/rails/activesupport/lib/active_support/dependencies.rb:142:in `load' vendor/rails/activesupport/lib/active_support/dependencies.rb:521:in `new_constants_in' vendor/rails/activesupport/lib/active_support/dependencies.rb:142:in `load' vendor/rails/railties/lib/commands/servers/mongrel.rb:64 /usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require' /usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `require' vendor/rails/activesupport/lib/active_support/dependencies.rb:153:in `require' vendor/rails/activesupport/lib/active_support/dependencies.rb:521:in `new_constants_in' vendor/rails/activesupport/lib/active_support/dependencies.rb:153:in `require' vendor/rails/railties/lib/commands/server.rb:49 /usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require' /usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `require' script/server:3 vendor/rails/actionpack/lib/action_controller/polymorphic_routes.rb:112:in `__send__' vendor/rails/actionpack/lib/action_controller/polymorphic_routes.rb:112:in `polymorphic_url' vendor/rails/actionpack/lib/action_controller/base.rb:628:in `url_for' app/controllers/users_controller.rb:16:in `login' vendor/rails/actionpack/lib/action_controller/base.rb:1256:in `send' vendor/rails/actionpack/lib/action_controller/base.rb:1256:in `perform_action_without_filters' vendor/rails/actionpack/lib/action_controller/filters.rb:617:in `call_filters' vendor/rails/actionpack/lib/action_controller/filters.rb:610:in `perform_action_without_benchmark' vendor/rails/actionpack/lib/action_controller/benchmarking.rb:68:in `perform_action_without_rescue' /usr/lib/ruby/1.8/benchmark.rb:293:in `measure' vendor/rails/actionpack/lib/action_controller/benchmarking.rb:68:in `perform_action_without_rescue' vendor/rails/actionpack/lib/action_controller/rescue.rb:136:in `perform_action_without_caching' vendor/rails/actionpack/lib/action_controller/caching/sql_cache.rb:13:in `perform_action' vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb:34:in `cache' vendor/rails/activerecord/lib/active_record/query_cache.rb:8:in `cache' vendor/rails/actionpack/lib/action_controller/caching/sql_cache.rb:12:in `perform_action' vendor/rails/actionpack/lib/action_controller/base.rb:524:in `send' vendor/rails/actionpack/lib/action_controller/base.rb:524:in `process_without_filters' vendor/rails/actionpack/lib/action_controller/filters.rb:606:in `process_without_session_management_support' vendor/rails/actionpack/lib/action_controller/session_management.rb:134:in `process' vendor/rails/actionpack/lib/action_controller/base.rb:392:in `process' vendor/rails/actionpack/lib/action_controller/dispatcher.rb:184:in `handle_request' vendor/rails/actionpack/lib/action_controller/dispatcher.rb:112:in `dispatch_unlocked' vendor/rails/actionpack/lib/action_controller/dispatcher.rb:125:in `dispatch' vendor/rails/actionpack/lib/action_controller/dispatcher.rb:124:in `synchronize' vendor/rails/actionpack/lib/action_controller/dispatcher.rb:124:in `dispatch' vendor/rails/actionpack/lib/action_controller/dispatcher.rb:134:in `dispatch_cgi' vendor/rails/actionpack/lib/action_controller/dispatcher.rb:41:in `dispatch' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/rails.rb:76:in `process' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/rails.rb:74:in `synchronize' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/rails.rb:74:in `process' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:159:in `process_client' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:158:in `each' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:158:in `process_client' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:285:in `run' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:285:in `initialize' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:285:in `new' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:285:in `run' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:268:in `initialize' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:268:in `new' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:268:in `run' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/configurator.rb:282:in `run' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/configurator.rb:281:in `each' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/configurator.rb:281:in `run' /var/lib/gems/1.8/gems/mongrel-1.1.5/bin/mongrel_rails:128:in `run' /var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/command.rb:212:in `run' /var/lib/gems/1.8/gems/mongrel-1.1.5/bin/mongrel_rails:281 vendor/rails/activesupport/lib/active_support/dependencies.rb:142:in `load_without_new_constant_marking' vendor/rails/activesupport/lib/active_support/dependencies.rb:142:in `load' vendor/rails/activesupport/lib/active_support/dependencies.rb:521:in `new_constants_in' vendor/rails/activesupport/lib/active_support/dependencies.rb:142:in `load' vendor/rails/railties/lib/commands/servers/mongrel.rb:64 /usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require' /usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `require' vendor/rails/activesupport/lib/active_support/dependencies.rb:153:in `require' vendor/rails/activesupport/lib/active_support/dependencies.rb:521:in `new_constants_in' vendor/rails/activesupport/lib/active_support/dependencies.rb:153:in `require' vendor/rails/railties/lib/commands/server.rb:49 /usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require' /usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `require' script/server:3 Request Parameters: None Show session dump --- :user: :csrf_id: 2927cca61bbbe97218362b5bcdb74c0f flash: !map:ActionController::Flash::FlashHash {} Response Headers: {"Content-Type"="", "cookie"=[], "Cache-Control"="no-cache"} Bear in mind that I had it working earlier-- url_for(:back) knew how to operate properly before I added this logic. Thanks in advance for any ideas!

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• Glassfish 3 Cant update JDK no way

  - by Parhs

  Hello.. I was using 1.6.0_19 jdk and installed 1.6.0_20 jdk.. Glassfish doesnt like that... Here are my windows environment variables.. ALLUSERSPROFILE=C:\ProgramData ANT_HOME=C:\apache-ant-1.8.1\ APPDATA=C:\Users\Parhs\AppData\Roaming CommonProgramFiles=C:\Program Files\Common Files COMPUTERNAME=PARHS-PC ComSpec=C:\Windows\system32\cmd.exe FP_NO_HOST_CHECK=NO HOMEDRIVE=C: HOMEPATH=\Users\Parhs JAVA_HOME=C:\Program Files\Java\jdk1.6.0_20\ LOCALAPPDATA=C:\Users\Parhs\AppData\Local LOGONSERVER=\\PARHS-PC NUMBER_OF_PROCESSORS=2 OS=Windows_NT Path=C:\Program Files\PHP\;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wb em;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Program Files\Toshiba\Bluetoot h Toshiba Stack\sys\;C:\Program Files\Microsoft SQL Server\90\Tools\binn\;C:\apa che-ant-1.8.1\bin PATHEXT=.COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.MSC PHPRC=C:\Program Files\PHP\php.ini PROCESSOR_ARCHITECTURE=x86 PROCESSOR_IDENTIFIER=x86 Family 6 Model 14 Stepping 8, GenuineIntel PROCESSOR_LEVEL=6 PROCESSOR_REVISION=0e08 ProgramData=C:\ProgramData ProgramFiles=C:\Program Files PROMPT=$P$G PSModulePath=C:\Windows\system32\WindowsPowerShell\v1.0\Modules\ PUBLIC=C:\Users\Public SESSIONNAME=Console SystemDrive=C: SystemRoot=C:\Windows TEMP=C:\Users\Parhs\AppData\Local\Temp TMP=C:\Users\Parhs\AppData\Local\Temp USERDOMAIN=Parhs-PC USERNAME=Parhs USERPROFILE=C:\Users\Parhs VS90COMNTOOLS=C:\Program Files\Microsoft Visual Studio 9.0\Common7\Tools\ windir=C:\Windows Also here is my asenv.bat REM DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER. REM REM Copyright 2004-2009 Sun Microsystems, Inc. All rights reserved. REM REM Use is subject to License Terms REM set AS_IMQ_LIB=....\mq\lib set AS_IMQ_BIN=....\mq\bin set AS_CONFIG=..\config set AS_INSTALL=.. set AS_DEF_DOMAINS_PATH=..\domains set AS_DERBY_INSTALL=....\javadb set AS_JAVA="C:\Program Files\Java\jdk1.6.0_20" And although restarting system and server i am getting this report Operating System Information: Name of the Operating System: Windows 7 Binary Architecture name of the Operating System: x86, Version: 6.1 Number of processors available on the Operating System: 2 System load on the available processors for the last minute: -1.0. (Sum of running and queued runnable entities per minute) General Java Runtime Environment Information for the VM: 6152@Parhs-PC JRE BootClassPath: C:\glassfishv3\glassfish/modules/endorsed\javax.annotation.jar;C:\glassfishv3\glassfish/modules/endorsed\jaxb-api-osgi.jar;C:\glassfishv3\glassfish/modules/endorsed\webservices-api-osgi.jar;C:\Program Files\Java\jdk1.6.0_19\jre\lib\resources.jar;C:\Program Files\Java\jdk1.6.0_19\jre\lib\rt.jar;C:\Program Files\Java\jdk1.6.0_19\jre\lib\sunrsasign.jar;C:\Program Files\Java\jdk1.6.0_19\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.6.0_19\jre\lib\jce.jar;C:\Program Files\Java\jdk1.6.0_19\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.6.0_19\jre\classes;C:\glassfishv3\glassfish\lib\monitor\btrace-boot.jar JRE ClassPath: C:\glassfishv3\glassfish\modules\glassfish.jar;C:\glassfishv3\glassfish\lib\monitor\btrace-agent.jar JRE Native Library Path: C:\Program Files\Java\jdk1.6.0_19\bin;.;C:\Windows\Sun\Java\bin;C:\Windows\system32;C:\Windows;C:\Program Files\PHP\;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Program Files\Toshiba\Bluetooth Toshiba Stack\sys\;C:\Program Files\Microsoft SQL Server\90\Tools\binn\;C:\apache-ant-1.8.1\bin JRE name: Java HotSpot(TM) Client VM Vendor: Sun Microsystems Inc. Version: 16.2-b04 List of System Properties for the Java Virtual Machine: ANTLR_USE_DIRECT_CLASS_LOADING = true AS_CONFIG = C:\glassfishv3\glassfish\config\..\config AS_DEF_DOMAINS_PATH = C:\glassfishv3\glassfish\config\..\domains AS_DERBY_INSTALL = C:\glassfishv3\glassfish\config\..\..\javadb AS_IMQ_BIN = C:\glassfishv3\glassfish\config\..\..\mq\bin AS_IMQ_LIB = C:\glassfishv3\glassfish\config\..\..\mq\lib AS_INSTALL = C:\glassfishv3\glassfish\config\.. AS_JAVA = C:\Program Files\Java\jdk1.6.0_20\jre GlassFish_Platform = Felix awt.toolkit = sun.awt.windows.WToolkit catalina.base = C:\glassfishv3\glassfish\domains\domain1 catalina.home = C:\glassfishv3\glassfish\domains\domain1 catalina.useNaming = false com.sun.aas.configRoot = C:\glassfishv3\glassfish\config com.sun.aas.derbyRoot = C:\glassfishv3\javadb com.sun.aas.domainsRoot = C:\glassfishv3\glassfish\domains com.sun.aas.hostName = Parhs-PC com.sun.aas.imqBin = C:\glassfishv3\mq\bin com.sun.aas.imqLib = C:\glassfishv3\mq\lib com.sun.aas.installRoot = C:\glassfishv3\glassfish com.sun.aas.installRootURI = file:/C:/glassfishv3/glassfish/ com.sun.aas.instanceName = server com.sun.aas.instanceRoot = C:\glassfishv3\glassfish\domains\domain1 com.sun.aas.instanceRootURI = file:/C:/glassfishv3/glassfish/domains/domain1/ com.sun.aas.javaRoot = C:\Program Files\Java\jdk1.6.0_19\jre com.sun.enterprise.config.config_environment_factory_class = com.sun.enterprise.config.serverbeans.AppserverConfigEnvironmentFactory com.sun.enterprise.hk2.cacheDir = C:\glassfishv3\glassfish\domains\domain1\osgi-cache\felix com.sun.enterprise.jaccprovider.property.repository = C:\glassfishv3\glassfish\domains\domain1/generated/policy com.sun.enterprise.security.httpsOutboundKeyAlias = s1as common.loader = ${catalina.home}/common/classes,${catalina.home}/common/endorsed/*.jar,${catalina.home}/common/lib/*.jar eclipselink.security.usedoprivileged = true ejb.home = C:\glassfishv3\glassfish\modules\ejb felix.config.properties = file:/C:/glassfishv3/glassfish/osgi/felix/conf/config.properties felix.fileinstall.bundles.new.start = true felix.fileinstall.debug = 1 felix.fileinstall.dir = C:\glassfishv3\glassfish/modules/autostart/ felix.fileinstall.poll = 5000 felix.system.properties = file:/C:/glassfishv3/glassfish/osgi/felix/conf/system.properties file.encoding = Cp1253 file.encoding.pkg = sun.io file.separator = \ glassfish.version = GlassFish v3 (build 74.2) hk2.startup.context.args = #Mon Jun 07 20:27:37 EEST 2010 -startup-classpath=C\:\\glassfishv3\\glassfish\\modules\\glassfish.jar;C\:\\glassfishv3\\glassfish\\lib\\monitor\\btrace-agent.jar __time_zero=1275931657334 hk2.startup.context.mainModule=org.glassfish.core.kernel -startup-args=--domain,,,domain1,,,--domaindir,,,C\:\\glassfishv3\\glassfish\\domains\\domain1 --domain=domain1 -startup-classname=com.sun.enterprise.glassfish.bootstrap.ASMain --domaindir=C\:\\glassfishv3\\glassfish\\domains\\domain1 hk2.startup.context.root = C:\glassfishv3\glassfish\modules http.nonProxyHosts = localhost|127.0.0.1|Parhs-PC java.awt.graphicsenv = sun.awt.Win32GraphicsEnvironment java.awt.printerjob = sun.awt.windows.WPrinterJob java.class.path = C:\glassfishv3\glassfish\modules\glassfish.jar;C:\glassfishv3\glassfish\lib\monitor\btrace-agent.jar java.class.version = 50.0 java.endorsed.dirs = C:\glassfishv3\glassfish/modules/endorsed;C:\glassfishv3\glassfish/lib/endorsed java.ext.dirs = C:\Program Files\Java\jdk1.6.0_19\jre/lib/ext;C:\Program Files\Java\jdk1.6.0_19\jre/jre/lib/ext;C:\glassfishv3\glassfish\domains\domain1/lib/ext java.home = C:\Program Files\Java\jdk1.6.0_19\jre java.io.tmpdir = C:\Users\Parhs\AppData\Local\Temp\ java.library.path = C:\Program Files\Java\jdk1.6.0_19\bin;.;C:\Windows\Sun\Java\bin;C:\Windows\system32;C:\Windows;C:\Program Files\PHP\;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Program Files\Toshiba\Bluetooth Toshiba Stack\sys\;C:\Program Files\Microsoft SQL Server\90\Tools\binn\;C:\apache-ant-1.8.1\bin java.net.useSystemProxies = true java.rmi.server.randomIDs = true java.runtime.name = Java(TM) SE Runtime Environment java.runtime.version = 1.6.0_19-b04 java.security.auth.login.config = C:\glassfishv3\glassfish\domains\domain1/config/login.conf java.security.policy = C:\glassfishv3\glassfish\domains\domain1/config/server.policy java.specification.name = Java Platform API Specification java.specification.vendor = Sun Microsystems Inc. java.specification.version = 1.6 java.util.logging.config.file = C:\glassfishv3\glassfish\domains\domain1\config\logging.properties java.vendor = Sun Microsystems Inc. java.vendor.url = http://java.sun.com/ java.vendor.url.bug = http://java.sun.com/cgi-bin/bugreport.cgi java.version = 1.6.0_19 java.vm.info = mixed mode java.vm.name = Java HotSpot(TM) Client VM java.vm.specification.name = Java Virtual Machine Specification java.vm.specification.vendor = Sun Microsystems Inc. java.vm.specification.version = 1.0 java.vm.vendor = Sun Microsystems Inc. java.vm.version = 16.2-b04 javax.net.ssl.keyStore = C:\glassfishv3\glassfish\domains\domain1/config/keystore.jks javax.net.ssl.keyStorePassword = changeit javax.net.ssl.trustStore = C:\glassfishv3\glassfish\domains\domain1/config/cacerts.jks javax.net.ssl.trustStorePassword = changeit javax.rmi.CORBA.PortableRemoteObjectClass = com.sun.corba.ee.impl.javax.rmi.PortableRemoteObject javax.rmi.CORBA.StubClass = com.sun.corba.ee.impl.javax.rmi.CORBA.StubDelegateImpl javax.rmi.CORBA.UtilClass = com.sun.corba.ee.impl.javax.rmi.CORBA.Util javax.security.jacc.PolicyConfigurationFactory.provider = com.sun.enterprise.security.provider.PolicyConfigurationFactoryImpl jdbc.drivers = org.apache.derby.jdbc.ClientDriver jpa.home = C:\glassfishv3\glassfish\modules\jpa line.separator = org.glassfish.web.rfc2109_cookie_names_enforced = false org.jvnet.hk2.osgimain.autostartBundles = osgi-adapter.jar, org.apache.felix.shell.jar, org.apache.felix.shell.remote.jar, org.apache.felix.configadmin.jar, org.apache.felix.fileinstall.jar org.jvnet.hk2.osgimain.bundlesDir = C:\glassfishv3\glassfish\modules org.jvnet.hk2.osgimain.excludedSubDirs = autostart/ org.omg.CORBA.ORBClass = com.sun.corba.ee.impl.orb.ORBImpl org.omg.CORBA.ORBSingletonClass = com.sun.corba.ee.impl.orb.ORBSingleton org.osgi.framework.storage = C:\glassfishv3\glassfish\domains\domain1\osgi-cache\felix os.arch = x86 os.name = Windows 7 os.version = 6.1 osgi.shell.telnet.ip = 127.0.0.1 osgi.shell.telnet.maxconn = 1 osgi.shell.telnet.port = 6666 package.access = package.definition = path.separator = ; security.home = C:\glassfishv3\glassfish\modules\security server.loader = ${catalina.home}/server/classes,${catalina.home}/server/lib/*.jar shared.loader = ${catalina.home}/shared/classes,${catalina.home}/shared/lib/*.jar sun.arch.data.model = 32 sun.boot.class.path = C:\glassfishv3\glassfish/modules/endorsed\javax.annotation.jar;C:\glassfishv3\glassfish/modules/endorsed\jaxb-api-osgi.jar;C:\glassfishv3\glassfish/modules/endorsed\webservices-api-osgi.jar;C:\Program Files\Java\jdk1.6.0_19\jre\lib\resources.jar;C:\Program Files\Java\jdk1.6.0_19\jre\lib\rt.jar;C:\Program Files\Java\jdk1.6.0_19\jre\lib\sunrsasign.jar;C:\Program Files\Java\jdk1.6.0_19\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.6.0_19\jre\lib\jce.jar;C:\Program Files\Java\jdk1.6.0_19\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.6.0_19\jre\classes;C:\glassfishv3\glassfish\lib\monitor\btrace-boot.jar sun.boot.library.path = C:\Program Files\Java\jdk1.6.0_19\jre\bin sun.cpu.endian = little sun.cpu.isalist = pentium_pro+mmx pentium_pro pentium+mmx pentium i486 i386 i86 sun.desktop = windows sun.io.unicode.encoding = UnicodeLittle sun.java.launcher = SUN_STANDARD sun.jnu.encoding = Cp1253 sun.management.compiler = HotSpot Client Compiler sun.os.patch.level = user.country = GR user.dir = C:\glassfishv3\glassfish\domains\domain1 user.home = C:\Users\Parhs user.language = el user.name = Parhs user.timezone = Europe/Athens user.variant = web.home = C:\glassfishv3\glassfish\modules\web weld.home = C:\glassfishv3\glassfish\modules\weld Why it is so damn hard??? What am i missing?

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• Memory leak involving jQuery Ajax requests

  - by Eli Courtwright

  I have a webpage that's leaking memory in both IE8 and Firefox; the memory usage displayed in the Windows Process Explorer just keeps growing over time. The following page requests the "unplanned.json" url, which is a static file that never changes (though I do set my Cache-control HTTP header to no-cache to make sure that the Ajax request always goes through). When it gets the results, it clears out an HTML table, loops over the json array it got back from the server, and dynamically adds a row to an HTML table for each entry in the array. Then it waits 2 seconds and repeats this process. Here's the entire webpage: <html> <head> <title>Test Page</title> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.3/jquery.min.js"></script> </head> <body> <script type="text/javascript"> function kickoff() { $.getJSON("unplanned.json", resetTable); } function resetTable(rows) { $("#content tbody").empty(); for(var i=0; i<rows.length; i++) { $("<tr>" + "<td>" + rows[i].mpe_name + "</td>" + "<td>" + rows[i].bin + "</td>" + "<td>" + rows[i].request_time + "</td>" + "<td>" + rows[i].filtered_delta + "</td>" + "<td>" + rows[i].failed_delta + "</td>" + "</tr>").appendTo("#content tbody"); } setTimeout(kickoff, 2000); } $(kickoff); </script> <table id="content" border="1" style="width:100% ; text-align:center"> <thead><tr> <th>MPE</th> <th>Bin</th> <th>When</th> <th>Filtered</th> <th>Failed</th> </tr></thead> <tbody></tbody> </table> </body> </html> If it helps, here's an example of the json I'm sending back (it's this exact array wuith thousands of entries instead of just one): [ { mpe_name: "DBOSS-995", request_time: "09/18/2009 11:51:06", bin: 4, filtered_delta: 1, failed_delta: 1 } ] EDIT: I've accepted Toran's extremely helpful answer, but I feel I should post some additional code, since his removefromdom jQuery plugin has some limitations: It only removes individual elements. So you can't give it a query like `$("#content tbody tr")` and expect it to remove all of the elements you've specified. Any element that you remove with it must have an `id` attribute. So if I want to remove my `tbody`, then I must assign an `id` to my `tbody` tag or else it will give an error. It removes the element itself and all of its descendants, so if you simply want to empty that element then you'll have to re-create it afterwards (or modify the plugin to empty instead of remove). So here's my page above modified to use Toran's plugin. For the sake of simplicity I didn't apply any of the general performance advice offered by Peter. Here's the page which now no longer memory leaks: <html> <head> <title>Test Page</title> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.3/jquery.min.js"></script> </head> <body> <script type="text/javascript"> <!-- $.fn.removefromdom = function(s) { if (!this) return; var el = document.getElementById(this.attr("id")); if (!el) return; var bin = document.getElementById("IELeakGarbageBin"); //before deleting el, recursively delete all of its children. while (el.childNodes.length > 0) { if (!bin) { bin = document.createElement("DIV"); bin.id = "IELeakGarbageBin"; document.body.appendChild(bin); } bin.appendChild(el.childNodes[el.childNodes.length - 1]); bin.innerHTML = ""; } el.parentNode.removeChild(el); if (!bin) { bin = document.createElement("DIV"); bin.id = "IELeakGarbageBin"; document.body.appendChild(bin); } bin.appendChild(el); bin.innerHTML = ""; }; var resets = 0; function kickoff() { $.getJSON("unplanned.json", resetTable); } function resetTable(rows) { $("#content tbody").removefromdom(); $("#content").append('<tbody id="id_field_required"></tbody>'); for(var i=0; i<rows.length; i++) { $("#content tbody").append("<tr><td>" + rows[i].mpe_name + "</td>" + "<td>" + rows[i].bin + "</td>" + "<td>" + rows[i].request_time + "</td>" + "<td>" + rows[i].filtered_delta + "</td>" + "<td>" + rows[i].failed_delta + "</td></tr>"); } resets++; $("#message").html("Content set this many times: " + resets); setTimeout(kickoff, 2000); } $(kickoff); // --> </script> <div id="message" style="color:red"></div> <table id="content" border="1" style="width:100% ; text-align:center"> <thead><tr> <th>MPE</th> <th>Bin</th> <th>When</th> <th>Filtered</th> <th>Failed</th> </tr></thead> <tbody id="id_field_required"></tbody> </table> </body> </html> FURTHER EDIT: I'll leave my question unchanged, though it's worth noting that this memory leak has nothing to do with Ajax. In fact, the following code would memory leak just the same and be just as easily solved with Toran's removefromdom jQuery plugin: function resetTable() { $("#content tbody").empty(); for(var i=0; i<1000; i++) { $("#content tbody").append("<tr><td>" + "DBOSS-095" + "</td>" + "<td>" + 4 + "</td>" + "<td>" + "09/18/2009 11:51:06" + "</td>" + "<td>" + 1 + "</td>" + "<td>" + 1 + "</td></tr>"); } setTimeout(resetTable, 2000); } $(resetTable);

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• Bogus InvalidOperationException (in a DataServiceRequestException)

  - by Andrei Rinea

  I am having a hard time with ADO.NET Data Services (formerly code-named Astoria) as it gives me a bogus exception when I try to insert a new entity from the silverlight client and trying in a clean project (the same code) doesn't. In both cases, however, data is correctly inserted into the database. Using Fiddler (an HTTP debugger I could see that there is no problem in the HTTP communication as I will show later in this question. The code : var ctx = new MyProject123Entities(new Uri("http://andreiri/MyProject.Data/Data.svc")); var i = new Zone() { Data = DateTime.Now, IdElement = 1 }; ctx.AddToZone(i); i.StareZone = new StareZone() { IdStareZone = 1 }; ctx.AttachTo("StareZone", i.StareZone); ctx.SetLink(i, "StareZone", i.StareZone); i.TipZone = new TipZone() { IdTipZone = 1 }; ctx.AttachTo("TipZone", i.TipZone); ctx.SetLink(i, "TipZone", i.TipZone); i.User = new User() { IdUser = 2 }; ctx.AttachTo("User", i.User); ctx.SetLink(i, "User", i.User); ctx.BeginSaveChanges(r =] ctx.EndSaveChanges(r), null); when run the last line (ctx.EndSaveChanges(r)) will throw the following exception : System.Data.Services.Client.DataServiceRequestException was unhandled by user code Message="An error occurred while processing this request." StackTrace: at System.Data.Services.Client.DataServiceContext.SaveAsyncResult.HandleBatchResponse() at System.Data.Services.Client.DataServiceContext.SaveAsyncResult.EndRequest() at System.Data.Services.Client.DataServiceContext.EndSaveChanges(IAsyncResult asyncResult) at MyProject.MainPage.[]c__DisplayClassd6.[]c__DisplayClassd8.[dashboard_PostZoneCurent]b__d5(IAsyncResult r) at System.Data.Services.Client.BaseAsyncResult.HandleCompleted() at System.Data.Services.Client.DataServiceContext.SaveAsyncResult.HandleCompleted(PerRequest pereq) at System.Data.Services.Client.DataServiceContext.SaveAsyncResult.AsyncEndRead(IAsyncResult asyncResult) at System.IO.Stream.BeginRead(Byte[] buffer, Int32 offset, Int32 count, AsyncCallback callback, Object state) at System.Data.Services.Client.DataServiceContext.SaveAsyncResult.AsyncEndGetResponse(IAsyncResult asyncResult) InnerException: System.InvalidOperationException Message="The context is already tracking a different entity with the same resource Uri." StackTrace: at System.Data.Services.Client.DataServiceContext.AttachTo(Uri identity, Uri editLink, String etag, Object entity, Boolean fail) at System.Data.Services.Client.MaterializeAtom.MoveNext() at System.Data.Services.Client.DataServiceContext.HandleResponsePost(ResourceBox entry, MaterializeAtom materializer, Uri editLink, String etag) at System.Data.Services.Client.DataServiceContext.SaveAsyncResult.[HandleBatchResponse]d__1d.MoveNext() InnerException: (there is no further information regarding the exception although the ADo.NET Data Service is configured to return detailed informations) However the row is inserted correctly and completely in the database. Using fiddler I can see that the request : <?xml version="1.0" encoding="utf-8" standalone="yes"?> <entry xmlns:d="http://schemas.microsoft.com/ado/2007/08/dataservices" xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata" xmlns="http://www.w3.org/2005/Atom"> <category scheme="http://schemas.microsoft.com/ado/2007/08/dataservices/scheme" term="MyProject123Model.Zone" /> <title /> <updated>2009-09-11T13:36:46.917157Z</updated> <author> <name /> </author> <id /> <link href="http://andreiri/MyProject.Data/Data.svc/StareZone(1)" rel="http://schemas.microsoft.com/ado/2007/08/dataservices/related/StareZone" type="application/atom+xml;type=entry" /> <link href="http://andreiri/MyProject.Data/Data.svc/TipZone(4)" rel="http://schemas.microsoft.com/ado/2007/08/dataservices/related/TipZone" type="application/atom+xml;type=entry" /> <link href="http://andreiri/MyProject.Data/Data.svc/User(4)" rel="http://schemas.microsoft.com/ado/2007/08/dataservices/related/User" type="application/atom+xml;type=entry" /> <content type="application/xml"> <m:properties> <d:Data m:type="Edm.DateTime">2009-09-11T16:36:40.588951+03:00</d:Data> <d:Detalii>aslkdfjasldkfj</d:Detalii> <d:IdElement m:type="Edm.Int32">1</d:IdElement> <d:IdZone m:type="Edm.Int32">0</d:IdZone> <d:X_Post m:type="Edm.Decimal">587647.4705</d:X_Post> <d:X_Repost m:type="Edm.Decimal" m:null="true" /> <d:Y_Post m:type="Edm.Decimal">325783.077599999</d:Y_Post> <d:Y_Repost m:type="Edm.Decimal" m:null="true" /> </m:properties> </content> </entry> is well accepted and a successful response is returned : HTTP/1.1 201 Created Date: Fri, 11 Sep 2009 13:36:47 GMT Server: Microsoft-IIS/6.0 X-Powered-By: ASP.NET X-AspNet-Version: 2.0.50727 DataServiceVersion: 1.0; Location: http://andreiri/MyProject.Data/Data.svc/Zone(75) Cache-Control: no-cache Content-Type: application/atom+xml;charset=utf-8 Content-Length: 2213 <?xml version="1.0" encoding="utf-8" standalone="yes"?> <entry xml:base="http://andreiri/MyProject.Data/Data.svc/" xmlns:d="http://schemas.microsoft.com/ado/2007/08/dataservices" xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata" xmlns="http://www.w3.org/2005/Atom"> <id>http://andreiri/MyProject.Data/Data.svc/Zone(75)</id> <title type="text"></title> <updated>2009-09-11T13:36:47Z</updated> <author> <name /> </author> <link rel="edit" title="Zone" href="Zone(75)" /> <link rel="http://schemas.microsoft.com/ado/2007/08/dataservices/related/CenterZone" type="application/atom+xml;type=feed" title="CenterZone" href="Zone(75)/CenterZone" /> <link rel="http://schemas.microsoft.com/ado/2007/08/dataservices/related/ZoneMobil" type="application/atom+xml;type=feed" title="ZoneMobil" href="Zone(75)/ZoneMobil" /> <link rel="http://schemas.microsoft.com/ado/2007/08/dataservices/related/StareZone" type="application/atom+xml;type=entry" title="StareZone" href="Zone(75)/StareZone" /> <link rel="http://schemas.microsoft.com/ado/2007/08/dataservices/related/TipZone" type="application/atom+xml;type=entry" title="TipZone" href="Zone(75)/TipZone" /> <link rel="http://schemas.microsoft.com/ado/2007/08/dataservices/related/User" type="application/atom+xml;type=entry" title="User" href="Zone(75)/User" /> <category term="MyProject123Model.Zone" scheme="http://schemas.microsoft.com ado/2007/08/dataservices/scheme" /> <content type="application/xml"> <m:properties> <d:IdZone m:type="Edm.Int32">75</d:IdZone> <d:X_Post m:type="Edm.Decimal">587647.4705</d:X_Post> <d:Y_Post m:type="Edm.Decimal">325783.077599999</d:Y_Post> <d:X_Repost m:type="Edm.Decimal" m:null="true" /> <d:Y_Repost m:type="Edm.Decimal" m:null="true" /> <d:Data m:type="Edm.DateTime">2009-09-11T16:36:40.588951+03:00</d:Data> <d:Detalii>aslkdfjasldkfj</d:Detalii> <d:IdElement m:type="Edm.Int32">1</d:IdElement> </m:properties> </content> </entry> Why do I get an exception? And, using this in a clean project does not throw the exception..

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• What is the difference between Anycast and GeoDNS / GeoIP wrt HA?

  - by Riyad

  Based on the Wikipedia description of Anycast, it includes both the distribution of a domain-name-to-many-IP-mapping across many DNS servers as well as replying to clients with the most geographically close (or fastest) server. In the context of a globally distributed, highly available site like google.com (or any CDN service with many global edge locations) this sounds like the two key features one would need. DNS services like Amazon's Route53, EasyDNS and DNSMadeEasy all advertise themselves as Anycast-enabled networks. Therefore my assumption is that each of these DNS services transparently offer me those two killer features: multi-IP-to-domain mapping AND routing clients to the closest node. However, each of these services seem to separate out these two functionalities, referring to the 2nd one (routing clients to closest node) as "GeoDNS", "GeoIP" or "Global Traffic Director" and charge extra for the service. If a core tenant of an Anycast-capable system is to already do this, why is this functionality being earmarked as this extra feature? What is this "GeoDNS" feature doing that a standard Anycast DNS service won't do (according to the definition of Anycast from Wikipedia -- I understand what is being advertised, just not why it isn't implied already). I get extra-confused when a DNS service like Route53 that doesn't support this nebulous "GeoDNS" feature lists functionality like: Fast – Using a global anycast network of DNS servers around the world, Route 53 is designed to automatically route your users to the optimal location depending on network conditions. As a result, the service offers low query latency for your end users, as well as low update latency for your DNS record management needs. ... which sounds exactly like what GeoDNS is intended to do, but geographically directing clients is something they explicitly don't support it yet. Ultimately I am looking for the two following features from a DNS provider: Map multiple IP addresses to a single domain name (like google.com, amazon.com, etc. does) Utilize a DNS service that will respond to client requests for that domain with the IP address of the nearest server to the requestee. As mentioned, it seems like this is all part of an "Anycast" DNS service (all of which these services are), but the features and marketing I see from them suggest otherwise, making me think I need to learn a bit more about how DNS works before making a deployment choice. Thanks in advance for any clarifications.

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• Project Euler #15

  - by Aistina

  Hey everyone, Last night I was trying to solve challenge #15 from Project Euler: Starting in the top left corner of a 2×2 grid, there are 6 routes (without backtracking) to the bottom right corner. How many routes are there through a 20×20 grid? I figured this shouldn't be so hard, so I wrote a basic recursive function: const int gridSize = 20; // call with progress(0, 0) static int progress(int x, int y) { int i = 0; if (x < gridSize) i += progress(x + 1, y); if (y < gridSize) i += progress(x, y + 1); if (x == gridSize && y == gridSize) return 1; return i; } I verified that it worked for a smaller grids such as 2×2 or 3×3, and then set it to run for a 20×20 grid. Imagine my surprise when, 5 hours later, the program was still happily crunching the numbers, and only about 80% done (based on examining its current position/route in the grid). Clearly I'm going about this the wrong way. How would you solve this problem? I'm thinking it should be solved using an equation rather than a method like mine, but that's unfortunately not a strong side of mine. Update: I now have a working version. Basically it caches results obtained before when a n×m block still remains to be traversed. Here is the code along with some comments: // the size of our grid static int gridSize = 20; // the amount of paths available for a "NxM" block, e.g. "2x2" => 4 static Dictionary<string, long> pathsByBlock = new Dictionary<string, long>(); // calculate the surface of the block to the finish line static long calcsurface(long x, long y) { return (gridSize - x) * (gridSize - y); } // call using progress (0, 0) static long progress(long x, long y) { // first calculate the surface of the block remaining long surface = calcsurface(x, y); long i = 0; // zero surface means only 1 path remains // (we either go only right, or only down) if (surface == 0) return 1; // create a textual representation of the remaining // block, for use in the dictionary string block = (gridSize - x) + "x" + (gridSize - y); // if a same block has not been processed before if (!pathsByBlock.ContainsKey(block)) { // calculate it in the right direction if (x < gridSize) i += progress(x + 1, y); // and in the down direction if (y < gridSize) i += progress(x, y + 1); // and cache the result! pathsByBlock[block] = i; } // self-explanatory :) return pathsByBlock[block]; } Calling it 20 times, for grids with size 1×1 through 20×20 produces the following output: There are 2 paths in a 1 sized grid 0,0110006 seconds There are 6 paths in a 2 sized grid 0,0030002 seconds There are 20 paths in a 3 sized grid 0 seconds There are 70 paths in a 4 sized grid 0 seconds There are 252 paths in a 5 sized grid 0 seconds There are 924 paths in a 6 sized grid 0 seconds There are 3432 paths in a 7 sized grid 0 seconds There are 12870 paths in a 8 sized grid 0,001 seconds There are 48620 paths in a 9 sized grid 0,0010001 seconds There are 184756 paths in a 10 sized grid 0,001 seconds There are 705432 paths in a 11 sized grid 0 seconds There are 2704156 paths in a 12 sized grid 0 seconds There are 10400600 paths in a 13 sized grid 0,001 seconds There are 40116600 paths in a 14 sized grid 0 seconds There are 155117520 paths in a 15 sized grid 0 seconds There are 601080390 paths in a 16 sized grid 0,0010001 seconds There are 2333606220 paths in a 17 sized grid 0,001 seconds There are 9075135300 paths in a 18 sized grid 0,001 seconds There are 35345263800 paths in a 19 sized grid 0,001 seconds There are 137846528820 paths in a 20 sized grid 0,0010001 seconds 0,0390022 seconds in total I'm accepting danben's answer, because his helped me find this solution the most. But upvotes also to Tim Goodman and Agos :) Bonus update: After reading Eric Lippert's answer, I took another look and rewrote it somewhat. The basic idea is still the same but the caching part has been taken out and put in a separate function, like in Eric's example. The result is some much more elegant looking code. // the size of our grid const int gridSize = 20; // magic. static Func<A1, A2, R> Memoize<A1, A2, R>(this Func<A1, A2, R> f) { // Return a function which is f with caching. var dictionary = new Dictionary<string, R>(); return (A1 a1, A2 a2) => { R r; string key = a1 + "x" + a2; if (!dictionary.TryGetValue(key, out r)) { // not in cache yet r = f(a1, a2); dictionary.Add(key, r); } return r; }; } // calculate the surface of the block to the finish line static long calcsurface(long x, long y) { return (gridSize - x) * (gridSize - y); } // call using progress (0, 0) static Func<long, long, long> progress = ((Func<long, long, long>)((long x, long y) => { // first calculate the surface of the block remaining long surface = calcsurface(x, y); long i = 0; // zero surface means only 1 path remains // (we either go only right, or only down) if (surface == 0) return 1; // calculate it in the right direction if (x < gridSize) i += progress(x + 1, y); // and in the down direction if (y < gridSize) i += progress(x, y + 1); // self-explanatory :) return i; })).Memoize(); By the way, I couldn't think of a better way to use the two arguments as a key for the dictionary. I googled around a bit, and it seems this is a common solution. Oh well.

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• Subversion vision and roadmap

  - by gbjbaanb

  Recently C Michael Pilato of the core subversion team posted a mail to the subversion dev mailing list suggesting a vision and roadmap for the future of Subversion. Naturally, he wanted as much feedback and response as possible which is why I'm posting this here - to elicit some suggestions and contributions from you, the administrators of Subversion. Any comments are welcome, and I shall feedback a synopsis with a link to this question to the dev mailing list. Similarly, I've created a post on StackOverflow to get feedback from the programmer/user side of things too. So, without further ado: Vision The first thing on his "vision statement" is: Subversion has no future as a DVCS tool. Let's just get that out there. At least two very successful such tools exist already, and to squeeze another horse into that race would be a poor investment of energy and talent. There's no need to suggest distributed features for subversion. If you want a DVCS, there should be no ill-feeling if you migrate to Git, Mercurial or Bazaar. As he says, its pointless trying to make SVN like them when they already exist, especially when there are different usage patterns that SVN should be targetting. The vision for Subversion is: Subversion exists to be universally recognized and adopted as an open-source, centralized version control system characterized by its reliability as a safe haven for valuable data; the simplicity of its model and usage; and its ability to support the needs of a wide variety of users and projects, from individuals to large-scale enterprise operations. Roadmap Several ideas were suggested as being "very nice to have" and are offered as the starting point of a future roadmap. These are: Obliterate Shelve/Checkpoint Repository-dictated Configuration Rename Tracking Improved Merging Improved Tree Conflict Handling Enterprise Authentication Mechanisms Forward History Searching Log Message Templates Repository-dictated Configuration If anyone has suggestions to add, or comments on these, the subversion community would welcome all of them. Community And lastly, there was a call for more people to become involved with Subversion development. As with most OSS projects it can be daunting to join, but there is now a push for more to be done to help. If you feel like you can contribute, please do so.

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• Spring @Transactional not creating required transaction

  - by Steve

  Ok, so I've finally bowed to peer pressure and started using Spring in my web app :-)... So I'm trying to get the transaction handling stuff to work, and I just can't seem to get it. My Spring configuration looks like this: <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p" xmlns:tx="http://www.springframework.org/schema/tx" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd"> <bean id="groupDao" class="mil.navy.ndms.conops.common.dao.impl.jpa.GroupDao" lazy-init="true"> <property name="entityManagerFactory" ><ref bean="entityManagerFactory"/></property> </bean> <!-- enables interpretation of the @Required annotation to ensure that dependency injection actually occures --> <bean class="org.springframework.beans.factory.annotation.RequiredAnnotationBeanPostProcessor"/> <!-- enables interpretation of the @PersistenceUnit/@PersistenceContext annotations providing convenient access to EntityManagerFactory/EntityManager --> <bean class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor"/> <!-- uses the persistence unit defined in the META-INF/persistence.xml JPA configuration file --> <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalEntityManagerFactoryBean"> <property name="persistenceUnitName" value="CONOPS_PU" /> </bean> <!-- transaction manager for use with a single JPA EntityManagerFactory for transactional data access to a single datasource --> <bean id="jpaTransactionManager" class="org.springframework.orm.jpa.JpaTransactionManager"> <property name="entityManagerFactory" ref="entityManagerFactory"/> </bean> <!-- enables interpretation of the @Transactional annotation for declerative transaction managment using the specified JpaTransactionManager --> <tx:annotation-driven transaction-manager="jpaTransactionManager" proxy-target-class="true"/> </beans> persistence.xml: <?xml version="1.0" encoding="UTF-8"?> <persistence version="1.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"> <persistence-unit name="CONOPS_PU" transaction-type="RESOURCE_LOCAL"> <provider>org.hibernate.ejb.HibernatePersistence</provider> ... Class mappings removed for brevity... <properties> <property name="hibernate.dialect" value="org.hibernate.dialect.Oracle10gDialect"/> <property name="hibernate.connection.autocommit" value="false"/> <property name="hibernate.connection.username" value="****"/> <property name="hibernate.connection.password" value="*****"/> <property name="hibernate.connection.driver_class" value="oracle.jdbc.OracleDriver"/> <property name="hibernate.connection.url" value="jdbc:oracle:thin:@*****:1521:*****"/> <property name="hibernate.cache.provider_class" value="org.hibernate.cache.NoCacheProvider"/> <property name="hibernate.hbm2ddl.auto" value="create"/> <property name="hibernate.show_sql" value="true"/> <property name="hibernate.format_sql" value="true"/> </properties> </persistence-unit> </persistence> The DAO method to save my domain object looks like this: @Transactional(propagation=Propagation.REQUIRES_NEW) protected final T saveOrUpdate (T model) { EntityManager em = emf.createEntityManager ( ); EntityTransaction trans = em.getTransaction ( ); System.err.println ("Transaction isActive () == " + trans.isActive ( )); if (em != null) { try { if (model.getId ( ) != null) { em.persist (model); em.flush (); } else { em.merge (model); em.flush (); } } finally { em.close (); } } return (model); } So I try to save a copy of my Group object using the following code in my test case: context = new ClassPathXmlApplicationContext(configs); dao = (GroupDao)context.getBean("groupDao"); dao.saveOrUpdate (new Group ()); This bombs with the following exception: javax.persistence.TransactionRequiredException: no transaction is in progress at org.hibernate.ejb.AbstractEntityManagerImpl.flush(AbstractEntityManagerImpl.java:301) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:48) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:37) at java.lang.reflect.Method.invoke(Method.java:600) at org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:341) at $Proxy26.flush(Unknown Source) at mil.navy.ndms.conops.common.dao.impl.jpa.GenericJPADao.saveOrUpdate(GenericJPADao.java:646) at mil.navy.ndms.conops.common.dao.impl.jpa.GroupDao.save(GroupDao.java:641) at mil.navy.ndms.conops.common.dao.impl.jpa.GroupDao$$FastClassByCGLIB$$50343b9b.invoke() at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:149) at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:622) at mil.navy.ndms.conops.common.dao.impl.jpa.GroupDao$$EnhancerByCGLIB$$7359ba58.save() at mil.navy.ndms.conops.common.dao.impl.jpa.GroupDaoTest.testGroupDaoSave(GroupDaoTest.java:91) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:48) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:37) at java.lang.reflect.Method.invoke(Method.java:600) at junit.framework.TestCase.runTest(TestCase.java:164) at junit.framework.TestCase.runBare(TestCase.java:130) at junit.framework.TestResult$1.protect(TestResult.java:106) at junit.framework.TestResult.runProtected(TestResult.java:124) at junit.framework.TestResult.run(TestResult.java:109) at junit.framework.TestCase.run(TestCase.java:120) at junit.framework.TestSuite.runTest(TestSuite.java:230) at junit.framework.TestSuite.run(TestSuite.java:225) at org.eclipse.jdt.internal.junit.runner.junit3.JUnit3TestReference.run(JUnit3TestReference.java:130) at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:460) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:673) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:386) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:196) In addition, I get the following warnings when Spring first starts. Since these reference the entityManagerFactory and the transactionManager, they probably have some bearing on the problem, but I've no been able to decipher them enough to know what: Mar 11, 2010 12:19:27 PM org.springframework.context.support.AbstractApplicationContext$BeanPostProcessorChecker postProcessAfterInitialization INFO: Bean 'entityManagerFactory' is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying) Mar 11, 2010 12:19:27 PM org.springframework.context.support.AbstractApplicationContext$BeanPostProcessorChecker postProcessAfterInitialization INFO: Bean 'entityManagerFactory' is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying) Mar 11, 2010 12:19:27 PM org.springframework.context.support.AbstractApplicationContext$BeanPostProcessorChecker postProcessAfterInitialization INFO: Bean 'jpaTransactionManager' is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying) Mar 11, 2010 12:19:27 PM org.springframework.context.support.AbstractApplicationContext$BeanPostProcessorChecker postProcessAfterInitialization INFO: Bean '(inner bean)' is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying) Mar 11, 2010 12:19:27 PM org.springframework.context.support.AbstractApplicationContext$BeanPostProcessorChecker postProcessAfterInitialization INFO: Bean '(inner bean)' is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying) Mar 11, 2010 12:19:27 PM org.springframework.context.support.AbstractApplicationContext$BeanPostProcessorChecker postProcessAfterInitialization INFO: Bean 'org.springframework.transaction.interceptor.TransactionAttributeSourceAdvisor' is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying) Mar 11, 2010 12:19:27 PM org.springframework.context.support.AbstractApplicationContext$BeanPostProcessorChecker postProcessAfterInitialization INFO: Bean 'org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor' is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying) Mar 11, 2010 12:19:27 PM org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons INFO: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@37003700: defining beans [groupDao,org.springframework.beans.factory.annotation.RequiredAnnotationBeanPostProcessor,org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor,entityManagerFactory,jpaTransactionManager,org.springframework.aop.config.internalAutoProxyCreator,org.springframework.transaction.interceptor.TransactionAttributeSourceAdvisor]; root of factory hierarchy Does anyone have any idea what I'm missing? I'm totally stumped... Thanks

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• Please help to clean up my RoR development environment

  - by PeterWong

  I started RoR development a few months ago, and being new to Mac... Time flies and now I have a lot different ruby versions, rails versions and gems versions located everywhere......And currently I installed rvm and things got even worst, all things messed! And so I started want to clean all things and use rvm again! I want to uninstall all gems, all rails, and all ruby versions, except the system's default one (the very old one born with the mac). Or any other better solutions or suggestions!? Please help! there is some info that I think will be useful: which -a ruby /opt/local/bin/ruby /opt/local/bin/ruby /usr/local/bin/ruby /usr/bin/ruby /usr/local/bin/ruby which -a rails /usr/local/bin/rails /usr/bin/rails /usr/local/bin/rails which -a compass # simliar for rspec and many other gems /usr/local/bin/compass /usr/local/bin/compass gem list *** LOCAL GEMS *** abstract (1.0.0) actionmailer (3.0.3, 3.0.1, 3.0.0, 3.0.0.rc2, 2.3.9, 2.3.5, 2.3.4) actionpack (3.0.3, 3.0.1, 3.0.0, 3.0.0.rc2, 2.3.9, 2.3.5, 2.3.4) activemodel (3.0.3, 3.0.1, 3.0.0, 3.0.0.rc2) activerecord (3.0.3, 3.0.1, 3.0.0, 3.0.0.rc2, 2.3.9, 2.3.5, 2.3.4) activeresource (3.0.3, 3.0.1, 3.0.0, 3.0.0.rc2, 2.3.9, 2.3.5, 2.3.4) activesupport (3.0.3, 3.0.1, 3.0.0, 3.0.0.rc2, 2.3.9, 2.3.5, 2.3.4) addressable (2.2.2) arel (2.0.6, 1.0.1, 1.0.0.rc1) authlogic (2.1.6, 2.1.3) aws-s3 (0.6.2) base32 (0.1.2) block_helpers (0.3.3) bluecloth (2.0.9) bowline (0.9.4) bowline-bundler (0.0.4) bson (1.1.2) builder (2.1.2) bundler (1.0.2, 1.0.0) compass (0.10.6) crack (0.1.7) devise (1.1.3) diff-lcs (1.1.2) differ (0.1.1) dynamic_form (1.1.3) engineyard (1.3.1) engineyard-serverside-adapter (1.3.3) erubis (2.6.6) escape (0.0.4) extlib (0.9.15) facebooker (1.0.75) faker (0.3.1) faraday (0.5.3, 0.5.2) fast_gettext (0.5.10, 0.4.17) fastercsv (1.5.3) fastthread (1.0.7) ffi (0.6.3) formatize (1.0.1) formtastic (1.1.0, 1.0.1) gemcutter (0.5.0) gettext (2.1.0) git (1.2.5) gosu (0.7.25 universal-darwin) haml (3.0.24, 3.0.23, 3.0.22, 3.0.21, 3.0.18) haml-rails (0.3.4) heroku (1.10.13, 1.9.13) highline (1.5.2) hirb (0.3.4, 0.3.3) hpricot (0.8.2) i18n (0.5.0, 0.4.2, 0.4.1, 0.3.7) jeweler (1.4.0) json (1.4.6) json_pure (1.4.3) linkedin (0.1.8) locale (2.0.5) mail (2.2.12, 2.2.11, 2.2.10, 2.2.9, 2.2.7, 2.2.6.1) memcache-client (1.8.5) meta_search (0.9.8, 0.9.7.2, 0.9.7.1, 0.9.6, 0.9.4) mime-types (1.16) mongo (1.1.2) mongoid (2.0.0.beta.20) multi_json (0.0.5) multipart-post (1.0.1) mysql (2.8.1) mysql2 (0.2.6, 0.2.4, 0.2.3) net-ldap (0.1.1) nice-ffi (0.4) nokogiri (1.4.4, 1.4.2) oa-basic (0.1.6) oa-core (0.1.6) oa-enterprise (0.1.6) oa-oauth (0.1.6) oa-openid (0.1.6) oauth (0.4.4, 0.4.3, 0.4.1) oauth-plugin (0.4.0.pre1) oauth2 (0.1.0) omniauth (0.1.6) paperclip (2.3.6, 2.3.4, 2.3.1.1) passenger (2.2.12) polyglot (0.3.1) pyu-ruby-sasl (0.0.3.2) querybuilder (0.9.2, 0.5.9) rack (1.2.1, 1.1.0, 1.0.1) rack-cache (0.5.3) rack-cache-purge (0.0.2, 0.0.1) rack-mount (0.6.13) rack-openid (1.2.0) rack-test (0.5.6, 0.5.4) railroady (0.11.2) rails (3.0.3, 3.0.1, 3.0.0, 3.0.0.rc2, 2.3.9, 2.3.5, 2.3.4) railties (3.0.3, 3.0.1, 3.0.0, 3.0.0.rc2) rake (0.8.7) RedCloth (3.0.4) rest-client (1.6.1) roxml (3.1.5) rscribd (1.2.0) rspec (2.3.0, 2.2.0, 2.1.0, 2.0.1) rspec-core (2.3.0, 2.2.1, 2.1.0, 2.0.1) rspec-expectations (2.3.0, 2.2.0, 2.1.0, 2.0.1) rspec-mocks (2.3.0, 2.2.0, 2.1.0, 2.0.1) rspec-rails (2.3.0, 2.2.0, 2.1.0, 2.0.1) ruby-hmac (0.4.0) ruby-mysql (2.9.3) ruby-ole (1.2.10.1) ruby-openid (2.1.8) ruby-openid-apps-discovery (1.2.0) ruby-recaptcha (1.0.2, 1.0.0) ruby-sdl-ffi (0.3) ruby-termios (0.9.6) ruby_parser (2.0.5) rubyforge (2.0.4) rubygame (2.6.4) rubygems-update (1.3.7) rubyless (0.7.0, 0.6.0, 0.3.5) rubyntlm (0.1.1) rubyzip2 (2.0.1) scribd_fu (2.0.6) searchlogic (2.4.27, 2.4.23) sequel (3.16.0, 3.15.0, 3.13.0) sexp_processor (3.0.5) shoulda (2.11.3) sinatra (1.0) slim (0.8.0) slim-rails (0.1.2) spreadsheet (0.6.4.1) sqlite3-ruby (1.3.2, 1.3.1) ssl_requirement (0.1.0) subdomain-fu (1.0.0.beta2, 0.5.4) supermodel (0.1.4) syntax (1.0.0) taps (0.3.13, 0.3.11) templater (1.0.0) temple (0.1.6) text-format (1.0.0) text-hyphen (1.0.0) thor (0.14.6, 0.14.4, 0.14.3, 0.14.1, 0.14.0) tilt (1.1) treetop (1.4.9, 1.4.8) tzinfo (0.3.23) uuidtools (2.1.1, 2.0.0) validates_timeliness (3.0.0.beta.4, 2.3.1) warden (0.10.7) will_paginate (3.0.pre2, 2.3.15, 2.3.14) xml-simple (1.0.12) ya2yaml (0.30) yajl-ruby (0.7.8, 0.7.7) yamltest (0.7.0) zena (0.16.9, 0.16.8) ====== I have ran sudo rvm implode and sudo rm -rf ~/.rvm, so no rvm now. gem env RubyGems Environment: - RUBYGEMS VERSION: 1.3.7 - RUBY VERSION: 1.8.7 (2009-06-12 patchlevel 174) [i686-darwin10.2.0] - INSTALLATION DIRECTORY: /usr/local/lib/ruby/gems/1.8 - RUBY EXECUTABLE: /usr/local/bin/ruby - EXECUTABLE DIRECTORY: /usr/local/bin - RUBYGEMS PLATFORMS: - ruby - x86-darwin-10 - GEM PATHS: - /usr/local/lib/ruby/gems/1.8 - /Users/peter/.gem/ruby/1.8 - GEM CONFIGURATION: - :update_sources => true - :verbose => true - :benchmark => false - :backtrace => false - :bulk_threshold => 1000 - :sources => ["http://rubygems.org/", "http://gems.github.com"] - REMOTE SOURCES: - http://rubygems.org/ - http://gems.github.com === ls -al /usr/local/lib/ total 5704 drwxr-xr-x 7 root wheel 238 Jun 1 2010 . drwxr-xr-x 9 root wheel 306 Dec 15 16:20 .. -rw-r--r-- 1 root wheel 1717208 Jun 1 2010 libruby-static.a -rwxr-xr-x 1 root wheel 1191880 Jun 1 2010 libruby.1.8.7.dylib lrwxrwxrwx 1 root wheel 19 Jun 1 2010 libruby.1.8.dylib -> libruby.1.8.7.dylib lrwxrwxrwx 1 root wheel 19 Jun 1 2010 libruby.dylib -> libruby.1.8.7.dylib drwxr-xr-x 6 root wheel 204 Jun 1 2010 ruby

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• Link aggregation with freebsd8 and a cicso 3550, what am i doing wrong?

  - by Flamewires

  Hey, I am trying to setup Link Aggrigation with LACP (well, anything that provides increased bandwidth and failover using my setup will work). I'm running FreeBSD 8.0 on 3 machines. M1 is running 2 10/100 ethernetcards setup for link aggrigation using lagg. for reference: ifconfig em0 up ifconfig tx0 up ifconfig create lagg0 ifconfig lagg0 laggproto lacp laggport tx0 laggport em0 192.168.1.16 netmask 255.255.255.0 I plugged them into ports 1 and 2 of a Cicso 3550. then ran: configure terminal interface range Fa0/1 - 2 switchport mode access switchport access vlan 1 channel-group 1 mode active (everythings in vlan 1) Now Im able to connect the other computers to other ports on the switch and failover works great, i can unplug cables in the middle of a transfer and the traffic gets rerouted. However, im not noticing any speed increase. My test setup: load balancing: i tried dst and src on the switch, neither seemed to give me a speed increase. I am SCPing 2 500 meg files from the lagg computer to other computers (one each) which are also running 10/100 full duplex cards. I get transfer speeds of about 11.2-11.4 Mbps to a single host, and about half that (5.9-6.2) Mbps when transferring to both at the same time. From what I understood with destination load balancing the router was suppose to balance traffic headed for 1 computer over 1 port and traffic headed for another over a diff(in this case) the other port. With destination-MAC address forwarding, when packets are forwarded to an EtherChannel, the packets are distributed across the ports in the channel based on the destination host MAC address of the incoming packet. Therefore, packets to the same destination are forwarded over the same port, and packets to a different destination are sent on a different port in the channel. For the 3550 series switch, when source-MAC address forwarding is used, load distribution based on the source and destination IP address is also enabled for routed IP traffic. All routed IP traffic chooses a port based on the source and destination IP address. Packets between two IP hosts always use the same port in the channel, and traffic between any other pair of hosts can use a different port in the channel. (Link) What am i doing wrong/what would i need to do to see a speed increase beyond what i could do with just a single card?

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• Is Steam for Mac effectively running as superuser?

  - by godDLL

  When you download the client it does not weigh too much, and seems to do very little. Inside the app bundle there is a script that—upon inspecting the environment and deciding you're not running Linux—launches the client, which downloads the full support environment and resources. For this to happen (all of this is saved inside the bundle, the app bundle gets updated in this process) Steam wants Universal Access for Assistive Devices, and your password. Cacheable resources, preferences (like keyboard shortcuts), support files (like game hardware requirement lookup tables) live inside the bundle, not in ~/Library/{Application Support|Preferences|Cache}; games' data get dumped into ~/Documents/Steam Content. I'd describe myself as a bit OCD (which really says a lot), and I wouldn't care that much still. I'd go comb this hairy mess and find out where stuff is, when and if I need to, even if it's in an unfamiliar place; that does not actually tick me off. Well, a little bit. What makes me concerned is the way Steam needs both Access for Assistive Devices, and my password to run. The former gives it the ability to talk very intimately with running apps and the underlying system; while the latter (admin account) could very well give it and it's publishers unrestricted access to all my software, hardware and data. With publishers like Rockstar using scene NOCD cracks to publish their games on Steam, I'm not so sure I'm OK with this. I'd like more games made available for the MacOS X and all the pretty machines that run it, but this arrangement does not seem very Mac-like to me. It looks like Valve is going around system security measures and best practices, foregoing sandboxing, code signing, relatively sane structured organization; all the things that would appeal to someone who's no fun at parties at all, and will die alone, in his long dead mother's basement… wait. Right. Anyway. Can we get some input on Steam for Mac security at the end-user machine, from someone who understands how Accessibility API works, whether games distributed on Steam can read and write outside the user homefolder, collect data from other running apps, or similar?

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• JSF 2.0 Problem

  - by Sarang

  I am doing a project where I am using JSF 2.0 & Primefaces UI Components. There is a tab view component with tabs, "Day","Week" & "Month". In all tab, I have to display Bar Charts in each. For the same, I am fetching three list using the following three method. In the following code, UpdateCountHelper is fetching the data from database. So, UpdateCountHelper is taking some time for fetching data. This is code for fetching lists : public List<UpdateCount> getDayUpdateCounts() { if (projectFlag == true) { if (displayFlag == 1) { dayUpdateCounts = UpdateCountHelper.getProjectUpdates(1); } else { dayUpdateCounts = UpdateCountHelper.getProjectUpdates(name, 1); } } else { dayUpdateCounts = UpdateCountHelper.getResourceUpdates(userName, 1); } return dayUpdateCounts; } public List<UpdateCount> getMonthUpdateCounts() { if (projectFlag == true) { if (displayFlag == 1) { monthUpdateCounts = UpdateCountHelper.getProjectUpdates(30); } else { monthUpdateCounts = UpdateCountHelper.getProjectUpdates(name, 30); } } else { monthUpdateCounts = UpdateCountHelper.getResourceUpdates(userName, 30); } return monthUpdateCounts; } public List<UpdateCount> getWeekUpdateCounts() { if (projectFlag == true) { if (displayFlag == 1) { weekUpdateCounts = UpdateCountHelper.getProjectUpdates(7); } else { weekUpdateCounts = UpdateCountHelper.getProjectUpdates(name, 7); } } else { weekUpdateCounts = UpdateCountHelper.getResourceUpdates(userName, 7); } return weekUpdateCounts; } This is code for UI of Bar Chart : <p:panel id="Chart"> <p:tabView dynamic="false" cache="false"> <p:tab title="Day"> <p:panel id="chartDayPanel"> <center> <h:outputText id="projectWiseDayText" rendered="#{systemUtilizationServiceBean.projectFlag}" value="Project Wise Day Update"/> <p:columnChart id="projectWiseDayUpdateChart" rendered="#{systemUtilizationServiceBean.projectFlag}" value="#{systemUtilizationServiceBean.dayUpdateCounts}" var="dayWiseUpdate" xfield="#{dayWiseUpdate.name}" height="200px" width="640px"> <p:chartSeries label="Project Wise Current Day Update" value="#{dayWiseUpdate.noUpdates}"/> </p:columnChart> <h:outputText id="resourceWiseDayText" rendered="#{systemUtilizationServiceBean.resourceFlag}" value="Resource Wise Day Update"/> <p:columnChart id="resourceWiseDayUpdateChart" rendered="#{systemUtilizationServiceBean.resourceFlag}" value="#{systemUtilizationServiceBean.dayUpdateCounts}" var="dayWiseResourceUpdate" xfield="#{dayWiseResourceUpdate.name}" height="200px" width="640px"> <p:chartSeries label="Resource Wise Current Day Update" value="#{dayWiseResourceUpdate.noUpdates}"/> </p:columnChart> </center> </p:panel> </p:tab> <p:tab title="Week"> <p:panel id="chartWeekPanel"> <center> <h:outputText id="projectWiseWeekText" rendered="#{systemUtilizationServiceBean.projectFlag}" value="Project Wise Week Update"/> <p:columnChart id="projectWiseWeekUpdateChart" rendered="#{systemUtilizationServiceBean.projectFlag}" value="#{systemUtilizationServiceBean.weekUpdateCounts}" var="weekWiseUpdate" xfield="#{weekWiseUpdate.name}" height="200px" width="640px"> <p:chartSeries label="Project Wise Current Week Update" value="#{weekWiseUpdate.noUpdates}"/> </p:columnChart> <h:outputText id="resourceWiseWeekText" rendered="#{systemUtilizationServiceBean.resourceFlag}" value="Resource Wise Week Update"/> <p:columnChart id="resourceWiseWeekUpdateChart" rendered="#{systemUtilizationServiceBean.resourceFlag}" value="#{systemUtilizationServiceBean.weekUpdateCounts}" var="weekWiseResourceUpdate" xfield="#{weekWiseResourceUpdate.name}" height="200px" width="640px"> <p:chartSeries label="Resource Wise Current Week Update" value="#{weekWiseResourceUpdate.noUpdates}"/> </p:columnChart> </center> </p:panel> </p:tab> <p:tab title="Month"> <p:panel id="chartMonthPanel"> <center> <h:outputText id="projectWiseMonthText" rendered="#{systemUtilizationServiceBean.projectFlag}" value="Project Wise Month Update"/> <p:columnChart id="projectWiseMonthUpdateChart" rendered="#{systemUtilizationServiceBean.projectFlag}" value="#{systemUtilizationServiceBean.monthUpdateCounts}" var="monthWiseUpdate" xfield="#{monthWiseUpdate.name}" height="200px" width="640px"> <p:chartSeries label="Project Wise Current Month Update" value="#{monthWiseUpdate.noUpdates}"/> </p:columnChart> <h:outputText id="resourceWiseMonthText" rendered="#{systemUtilizationServiceBean.resourceFlag}" value="Resource Wise Month Update"/> <p:columnChart id="resourceWiseMonthUpdateChart" rendered="#{systemUtilizationServiceBean.resourceFlag}" value="#{systemUtilizationServiceBean.monthUpdateCounts}" var="monthWiseResourceUpdate" xfield="#{monthWiseResourceUpdate.name}" height="200px" width="640px"> <p:chartSeries label="Resource Wise Current Month Update" value="#{monthWiseResourceUpdate.noUpdates}"/> </p:columnChart> </center> </p:panel> </p:tab> </p:tabView> </p:panel> Now, I have to display same data in other tabview with same tabs as mentioned above & only thing is now I have to display in Pie Chart. Now in pie chart, I am using the same lists. So, it will again fetch the data from database & waste time. To solve that problem I have created other three lists & have given only reference of those previous lists. So, now no database fetching occur. The Code for applying the reference is : public List<UpdateCount> getPieDayUpdateCounts() { pieDayUpdateCounts = dayUpdateCounts; return pieDayUpdateCounts; } public List<UpdateCount> getPieMonthUpdateCounts() { pieMonthUpdateCounts = monthUpdateCounts; return pieMonthUpdateCounts; } public List<UpdateCount> getPieWeekUpdateCounts() { pieWeekUpdateCounts = weekUpdateCounts; return pieWeekUpdateCounts; } But, over here the problem occurring is that only chart of which the tab is enable is displayed but the other remaining 2 tabs are not showing any chart. The code for UI is : <p:tabView dynamic="false" cache="false"> <p:tab title="Day"> <center> <p:panel id="pieChartDayPanel"> <h:outputText id="projectWiseDayPieChartText" rendered="#{systemUtilizationServiceBean.projectFlag}" value="Project Wise Day Update"/> <p:pieChart id="projectWiseDayUpdatePieChart" rendered="#{systemUtilizationServiceBean.projectFlag}" value="#{systemUtilizationServiceBean.dayUpdateCounts}" var="dayWisePieUpdate" categoryField="#{dayWisePieUpdate.name}" dataField="#{dayWisePieUpdate.noUpdates}" height="200" width="200"/> <h:outputText id="resourceWiseDayPieChartText" rendered="#{systemUtilizationServiceBean.resourceFlag}" value="Resource Wise Day Update"/> <p:pieChart id="resourceWiseDayUpdatePieChart" rendered="#{systemUtilizationServiceBean.resourceFlag}" value="#{systemUtilizationServiceBean.dayUpdateCounts}" var="dayWiseResourcePieUpdate" categoryField="#{dayWiseResourcePieUpdate.name}" dataField="#{dayWiseResourcePieUpdate.noUpdates}" height="200" width="200"/> </p:panel> </center> </p:tab> <p:tab title="Week"> <center> <p:panel id="pieChartWeekPanel"> <h:outputText id="projectWiseWeekPieChartText" rendered="#{systemUtilizationServiceBean.projectFlag}" value="Project Wise Week Update"/> <p:pieChart id="projectWiseWeekUpdatePieChart" rendered="#{systemUtilizationServiceBean.projectFlag}" value="#{systemUtilizationServiceBean.weekUpdateCounts}" var="weekWisePieUpdate" categoryField="#{weekWisePieUpdate.name}" dataField="#{weekWisePieUpdate.noUpdates}" height="200" width="200"/> <h:outputText id="resourceWiseWeekPieChartText" rendered="#{systemUtilizationServiceBean.resourceFlag}" value="Resource Wise Week Update"/> <p:pieChart id="resourceWiseWeekUpdatePieChart" rendered="#{systemUtilizationServiceBean.resourceFlag}" value="#{systemUtilizationServiceBean.weekUpdateCounts}" var="weekWiseResourcePieUpdate" categoryField="#{weekWiseResourcePieUpdate.name}" dataField="#{weekWiseResourcePieUpdate.noUpdates}" height="200" width="200"/> </p:panel> </center> </p:tab> <p:tab title="Month"> <center> <p:panel id="pieChartMonthPanel"> <h:outputText id="projectWiseMonthPieChartText" rendered="#{systemUtilizationServiceBean.projectFlag}" value="Project Wise Month Update"/> <p:pieChart id="projectWiseMonthUpdatePieChart" rendered="#{systemUtilizationServiceBean.projectFlag}" value="#{systemUtilizationServiceBean.monthUpdateCounts}" var="monthWisePieUpdate" categoryField="#{monthWisePieUpdate.name}" dataField="#{monthWisePieUpdate.noUpdates}" height="200" width="200"/> <h:outputText id="resourceWiseMonthPieChartText" rendered="#{systemUtilizationServiceBean.resourceFlag}" value="Resource Wise Month Update"/> <p:pieChart id="resourceWiseMonthUpdatePieChart" rendered="#{systemUtilizationServiceBean.resourceFlag}" value="#{systemUtilizationServiceBean.monthUpdateCounts}" var="monthWiseResourcePieUpdate" categoryField="#{monthWiseResourcePieUpdate.name}" dataField="#{monthWiseResourcePieUpdate.noUpdates}" height="200" width="200"/> </p:panel> </center> </p:tab> </p:tabView> What should be the reason behind this ?

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