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• UIButton performance in UITableViewCell vs UIView

  - by marcel salathe

  I'd like to add a UIButton to a custom UITableViewCell (programmatically). This is easy to do, but I'm finding that the "performance" of the button in the cell is slow - that is, when I touch the button, there is quite a bit of delay until the button visually goes into the highlighted state. The same type of button on a regular UIView is very responsive in comparison. In order to isolate the problem, I've created two views - one is a simple UIView, the other is a UITableView with only one UITableViewCell. I've added buttons to both views (the UIView and the UITableViewCell), and the performance difference is quite striking. I've searched the web and read the Apple docs but haven't really found the cause of the problem. My guess is that it somehow has to do with the responder chain, but I can't quite put my finger on it. I must be doing something wrong, and I'd appreciate any help. Thanks. Demo code: ViewController.h #import <UIKit/UIKit.h> @interface ViewController : UIViewController <UITableViewDelegate, UITableViewDataSource> @property UITableView* myTableView; @property UIView* myView; ViewController.m #import "ViewController.h" #import "CustomCell.h" @implementation ViewController @synthesize myTableView, myView; - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil { self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]; if (self) { [self initMyView]; [self initMyTableView]; } return self; } - (void) initMyView { UIView* newView = [[UIView alloc] initWithFrame:CGRectMake(0,0,[[UIScreen mainScreen] bounds].size.width,100)]; self.myView = newView; // button on regularView UIButton* myButton = [UIButton buttonWithType:UIButtonTypeRoundedRect]; [myButton addTarget:self action:@selector(pressedMyButton) forControlEvents:UIControlEventTouchUpInside]; [myButton setTitle:@"I'm fast" forState:UIControlStateNormal]; [myButton setFrame:CGRectMake(20.0, 10.0, 160.0, 30.0)]; [[self myView] addSubview:myButton]; } - (void) initMyTableView { UITableView *newTableView = [[UITableView alloc] initWithFrame:CGRectMake(0,100,[[UIScreen mainScreen] bounds].size.width,[[UIScreen mainScreen] bounds].size.height-100) style:UITableViewStyleGrouped]; self.myTableView = newTableView; self.myTableView.delegate = self; self.myTableView.dataSource = self; } -(void) pressedMyButton { NSLog(@"pressedMyButton"); } - (void)viewDidLoad { [super viewDidLoad]; [[self view] addSubview:self.myView]; [[self view] addSubview:self.myTableView]; } - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView { return 1; } - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { return 1; } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { CustomCell *customCell = [tableView dequeueReusableCellWithIdentifier:@"CustomCell"]; if (customCell == nil) { customCell = [[CustomCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:@"CustomCell"]; } return customCell; } @end CustomCell.h #import <UIKit/UIKit.h> @interface CustomCell : UITableViewCell @property (retain, nonatomic) UIButton* cellButton; @end CustomCell.m #import "CustomCell.h" @implementation CustomCell @synthesize cellButton; - (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier { self = [super initWithStyle:style reuseIdentifier:reuseIdentifier]; if (self) { // button within cell cellButton = [UIButton buttonWithType:UIButtonTypeRoundedRect]; [cellButton addTarget:self action:@selector(pressedCellButton) forControlEvents:UIControlEventTouchUpInside]; [cellButton setTitle:@"I'm sluggish" forState:UIControlStateNormal]; [cellButton setFrame:CGRectMake(20.0, 10.0, 160.0, 30.0)]; [self addSubview:cellButton]; } return self; } - (void) pressedCellButton { NSLog(@"pressedCellButton"); } @end

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• My application had a WindowsIdentity crisis

  - by Brian Donahue

  The project I have been working on this week to test computer environments needs to do various actions as a user other than the one running the application. For instance, it looks up an installed Windows Service, finds out who the startup user is, and tries to connect to a database as that Windows user. Later on, it will need to access a file in the context of the currently logged-in user. With ASP .NET, this is super-easy: just go into Web.Config and set up the "identity impersonate" node, which can either impersonate a named user or the one who had logged into the website if authentication was enabled. With Windows applications, this is not so straightforward. There may be something I am overlooking, but the limitation seems to be that you can only change the security context on the current thread: any threads spawned by the impersonated thread also inherit the impersonated credentials. Impersonation is easy enough to do, once you figure out how. Here is my code for impersonating a user on the current thread:         using System;         using System.ComponentModel;         using System.Runtime.InteropServices;         using System.Security.Principal;         public class ImpersonateUser         {                 IntPtr userHandle;   [DllImport("advapi32.dll", SetLastError = true)]                 static extern bool LogonUser(                         string lpszUsername,                         string lpszDomain,                         string lpszPassword,                         LogonType dwLogonType,                         LogonProvider dwLogonProvider,                         out IntPtr phToken                         );                     [DllImport("kernel32.dll", SetLastError = true)]                 static extern bool CloseHandle(IntPtr hHandle);                     enum LogonType : int                 {                         Interactive = 2,                         Network = 3,                         Batch = 4,                         Service = 5,                         NetworkCleartext = 8,                         NewCredentials = 9,                 }                     enum LogonProvider : int                 {                         Default = 0,                 }                 public static WindowsImpersonationContext Impersonate(string user, string domain, string password)                 {   IntPtr userHandle = IntPtr.Zero;                         bool loggedOn = LogonUser(                                 user,                                 domain,                                 password,                                 LogonType.Interactive,                                 LogonProvider.Default,                                 out userHandle);                               if (!loggedOn)                         throw new Win32Exception(Marshal.GetLastWin32Error());                           WindowsIdentity identity = new WindowsIdentity(userHandle);                         WindowsPrincipal principal = new WindowsPrincipal(identity);                         System.Threading.Thread.CurrentPrincipal = principal;                         return identity.Impersonate();   }         }   /* Call impersonation */ ImpersonateUser.Impersonate("UserName","DomainName","Password"); /* When you want to go back to the original user */ WindowsIdentity.Impersonate(IntPtr.Zero); When you want to stop impersonating, you can call Impersonate() again with a null pointer. This will allow you to simulate a variety of different Windows users from the same applicaiton.

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• What is the fastest cyclic synchronization in Java (ExecutorService vs. CyclicBarrier vs. X)?

  - by Alex Dunlop

  Which Java synchronization construct is likely to provide the best performance for a concurrent, iterative processing scenario with a fixed number of threads like the one outlined below? After experimenting on my own for a while (using ExecutorService and CyclicBarrier) and being somewhat surprised by the results, I would be grateful for some expert advice and maybe some new ideas. Existing questions here do not seem to focus primarily on performance, hence this new one. Thanks in advance! The core of the app is a simple iterative data processing algorithm, parallelized to the spread the computational load across 8 cores on a Mac Pro, running OS X 10.6 and Java 1.6.0_07. The data to be processed is split into 8 blocks and each block is fed to a Runnable to be executed by one of a fixed number of threads. Parallelizing the algorithm was fairly straightforward, and it functionally works as desired, but its performance is not yet what I think it could be. The app seems to spend a lot of time in system calls synchronizing, so after some profiling I wonder whether I selected the most appropriate synchronization mechanism(s). A key requirement of the algorithm is that it needs to proceed in stages, so the threads need to sync up at the end of each stage. The main thread prepares the work (very low overhead), passes it to the threads, lets them work on it, then proceeds when all threads are done, rearranges the work (again very low overhead) and repeats the cycle. The machine is dedicated to this task, Garbage Collection is minimized by using per-thread pools of pre-allocated items, and the number of threads can be fixed (no incoming requests or the like, just one thread per CPU core). V1 - ExecutorService My first implementation used an ExecutorService with 8 worker threads. The program creates 8 tasks holding the work and then lets them work on it, roughly like this: // create one thread per CPU executorService = Executors.newFixedThreadPool( 8 ); ... // now process data in cycles while( ...) { // package data into 8 work items ... // create one Callable task per work item ... // submit the Callables to the worker threads executorService.invokeAll( taskList ); } This works well functionally (it does what it should), and for very large work items indeed all 8 CPUs become highly loaded, as much as the processing algorithm would be expected to allow (some work items will finish faster than others, then idle). However, as the work items become smaller (and this is not really under the program's control), the user CPU load shrinks dramatically: blocksize | system | user | cycles/sec 256k 1.8% 85% 1.30 64k 2.5% 77% 5.6 16k 4% 64% 22.5 4096 8% 56% 86 1024 13% 38% 227 256 17% 19% 420 64 19% 17% 948 16 19% 13% 1626 Legend: - block size = size of the work item (= computational steps) - system = system load, as shown in OS X Activity Monitor (red bar) - user = user load, as shown in OS X Activity Monitor (green bar) - cycles/sec = iterations through the main while loop, more is better The primary area of concern here is the high percentage of time spent in the system, which appears to be driven by thread synchronization calls. As expected, for smaller work items, ExecutorService.invokeAll() will require relatively more effort to sync up the threads versus the amount of work being performed in each thread. But since ExecutorService is more generic than it would need to be for this use case (it can queue tasks for threads if there are more tasks than cores), I though maybe there would be a leaner synchronization construct. V2 - CyclicBarrier The next implementation used a CyclicBarrier to sync up the threads before receiving work and after completing it, roughly as follows: main() { // create the barrier barrier = new CyclicBarrier( 8 + 1 ); // create Runable for thread, tell it about the barrier Runnable task = new WorkerThreadRunnable( barrier ); // start the threads for( int i = 0; i < 8; i++ ) { // create one thread per core new Thread( task ).start(); } while( ... ) { // tell threads about the work ... // N threads + this will call await(), then system proceeds barrier.await(); // ... now worker threads work on the work... // wait for worker threads to finish barrier.await(); } } class WorkerThreadRunnable implements Runnable { CyclicBarrier barrier; WorkerThreadRunnable( CyclicBarrier barrier ) { this.barrier = barrier; } public void run() { while( true ) { // wait for work barrier.await(); // do the work ... // wait for everyone else to finish barrier.await(); } } } Again, this works well functionally (it does what it should), and for very large work items indeed all 8 CPUs become highly loaded, as before. However, as the work items become smaller, the load still shrinks dramatically: blocksize | system | user | cycles/sec 256k 1.9% 85% 1.30 64k 2.7% 78% 6.1 16k 5.5% 52% 25 4096 9% 29% 64 1024 11% 15% 117 256 12% 8% 169 64 12% 6.5% 285 16 12% 6% 377 For large work items, synchronization is negligible and the performance is identical to V1. But unexpectedly, the results of the (highly specialized) CyclicBarrier seem MUCH WORSE than those for the (generic) ExecutorService: throughput (cycles/sec) is only about 1/4th of V1. A preliminary conclusion would be that even though this seems to be the advertised ideal use case for CyclicBarrier, it performs much worse than the generic ExecutorService. V3 - Wait/Notify + CyclicBarrier It seemed worth a try to replace the first cyclic barrier await() with a simple wait/notify mechanism: main() { // create the barrier // create Runable for thread, tell it about the barrier // start the threads while( ... ) { // tell threads about the work // for each: workerThreadRunnable.setWorkItem( ... ); // ... now worker threads work on the work... // wait for worker threads to finish barrier.await(); } } class WorkerThreadRunnable implements Runnable { CyclicBarrier barrier; @NotNull volatile private Callable<Integer> workItem; WorkerThreadRunnable( CyclicBarrier barrier ) { this.barrier = barrier; this.workItem = NO_WORK; } final protected void setWorkItem( @NotNull final Callable<Integer> callable ) { synchronized( this ) { workItem = callable; notify(); } } public void run() { while( true ) { // wait for work while( true ) { synchronized( this ) { if( workItem != NO_WORK ) break; try { wait(); } catch( InterruptedException e ) { e.printStackTrace(); } } } // do the work ... // wait for everyone else to finish barrier.await(); } } } Again, this works well functionally (it does what it should). blocksize | system | user | cycles/sec 256k 1.9% 85% 1.30 64k 2.4% 80% 6.3 16k 4.6% 60% 30.1 4096 8.6% 41% 98.5 1024 12% 23% 202 256 14% 11.6% 299 64 14% 10.0% 518 16 14.8% 8.7% 679 The throughput for small work items is still much worse than that of the ExecutorService, but about 2x that of the CyclicBarrier. Eliminating one CyclicBarrier eliminates half of the gap. V4 - Busy wait instead of wait/notify Since this app is the primary one running on the system and the cores idle anyway if they're not busy with a work item, why not try a busy wait for work items in each thread, even if that spins the CPU needlessly. The worker thread code changes as follows: class WorkerThreadRunnable implements Runnable { // as before final protected void setWorkItem( @NotNull final Callable<Integer> callable ) { workItem = callable; } public void run() { while( true ) { // busy-wait for work while( true ) { if( workItem != NO_WORK ) break; } // do the work ... // wait for everyone else to finish barrier.await(); } } } Also works well functionally (it does what it should). blocksize | system | user | cycles/sec 256k 1.9% 85% 1.30 64k 2.2% 81% 6.3 16k 4.2% 62% 33 4096 7.5% 40% 107 1024 10.4% 23% 210 256 12.0% 12.0% 310 64 11.9% 10.2% 550 16 12.2% 8.6% 741 For small work items, this increases throughput by a further 10% over the CyclicBarrier + wait/notify variant, which is not insignificant. But it is still much lower-throughput than V1 with the ExecutorService. V5 - ? So what is the best synchronization mechanism for such a (presumably not uncommon) problem? I am weary of writing my own sync mechanism to completely replace ExecutorService (assuming that it is too generic and there has to be something that can still be taken out to make it more efficient). It is not my area of expertise and I'm concerned that I'd spend a lot of time debugging it (since I'm not even sure my wait/notify and busy wait variants are correct) for uncertain gain. Any advice would be greatly appreciated.

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• Is it inefficient to emit QByteArray?

  - by ShaChris23

  My application is a network application. Its job is to receive streams of packets (QByteArray) in which I would like to emit them as signals. Would doing so be inefficient? I'm concerned with copying of large buffers.

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• Null-free "maps": Is a callback solution slower than tryGet()?

  - by David Moles

  In comments to "How to implement List, Set, and Map in null free design?", Steven Sudit and I got into a discussion about using a callback, with handlers for "found" and "not found" situations, vs. a tryGet() method, taking an out parameter and returning a boolean indicating whether the out parameter had been populated. Steven maintained that the callback approach was more complex and almost certain to be slower; I maintained that the complexity was no greater and the performance at worst the same. But code speaks louder than words, so I thought I'd implement both and see what I got. The original question was fairly theoretical with regard to language ("And for argument sake, let's say this language don't even have null") -- I've used Java here because that's what I've got handy. Java doesn't have out parameters, but it doesn't have first-class functions either, so style-wise, it should suck equally for both approaches. (Digression: As far as complexity goes: I like the callback design because it inherently forces the user of the API to handle both cases, whereas the tryGet() design requires callers to perform their own boilerplate conditional check, which they could forget or get wrong. But having now implemented both, I can see why the tryGet() design looks simpler, at least in the short term.) First, the callback example: class CallbackMap<K, V> { private final Map<K, V> backingMap; public CallbackMap(Map<K, V> backingMap) { this.backingMap = backingMap; } void lookup(K key, Callback<K, V> handler) { V val = backingMap.get(key); if (val == null) { handler.handleMissing(key); } else { handler.handleFound(key, val); } } } interface Callback<K, V> { void handleFound(K key, V value); void handleMissing(K key); } class CallbackExample { private final Map<String, String> map; private final List<String> found; private final List<String> missing; private Callback<String, String> handler; public CallbackExample(Map<String, String> map) { this.map = map; found = new ArrayList<String>(map.size()); missing = new ArrayList<String>(map.size()); handler = new Callback<String, String>() { public void handleFound(String key, String value) { found.add(key + ": " + value); } public void handleMissing(String key) { missing.add(key); } }; } void test() { CallbackMap<String, String> cbMap = new CallbackMap<String, String>(map); for (int i = 0, count = map.size(); i < count; i++) { String key = "key" + i; cbMap.lookup(key, handler); } System.out.println(found.size() + " found"); System.out.println(missing.size() + " missing"); } } Now, the tryGet() example -- as best I understand the pattern (and I might well be wrong): class TryGetMap<K, V> { private final Map<K, V> backingMap; public TryGetMap(Map<K, V> backingMap) { this.backingMap = backingMap; } boolean tryGet(K key, OutParameter<V> valueParam) { V val = backingMap.get(key); if (val == null) { return false; } valueParam.value = val; return true; } } class OutParameter<V> { V value; } class TryGetExample { private final Map<String, String> map; private final List<String> found; private final List<String> missing; public TryGetExample(Map<String, String> map) { this.map = map; found = new ArrayList<String>(map.size()); missing = new ArrayList<String>(map.size()); } void test() { TryGetMap<String, String> tgMap = new TryGetMap<String, String>(map); for (int i = 0, count = map.size(); i < count; i++) { String key = "key" + i; OutParameter<String> out = new OutParameter<String>(); if (tgMap.tryGet(key, out)) { found.add(key + ": " + out.value); } else { missing.add(key); } } System.out.println(found.size() + " found"); System.out.println(missing.size() + " missing"); } } And finally, the performance test code: public static void main(String[] args) { int size = 200000; Map<String, String> map = new HashMap<String, String>(); for (int i = 0; i < size; i++) { String val = (i % 5 == 0) ? null : "value" + i; map.put("key" + i, val); } long totalCallback = 0; long totalTryGet = 0; int iterations = 20; for (int i = 0; i < iterations; i++) { { TryGetExample tryGet = new TryGetExample(map); long tryGetStart = System.currentTimeMillis(); tryGet.test(); totalTryGet += (System.currentTimeMillis() - tryGetStart); } System.gc(); { CallbackExample callback = new CallbackExample(map); long callbackStart = System.currentTimeMillis(); callback.test(); totalCallback += (System.currentTimeMillis() - callbackStart); } System.gc(); } System.out.println("Avg. callback: " + (totalCallback / iterations)); System.out.println("Avg. tryGet(): " + (totalTryGet / iterations)); } On my first attempt, I got 50% worse performance for callback than for tryGet(), which really surprised me. But, on a hunch, I added some garbage collection, and the performance penalty vanished. This fits with my instinct, which is that we're basically talking about taking the same number of method calls, conditional checks, etc. and rearranging them. But then, I wrote the code, so I might well have written a suboptimal or subconsicously penalized tryGet() implementation. Thoughts?

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• jQuery and Windows Azure

  - by Stephen Walther

  The goal of this blog entry is to describe how you can host a simple Ajax application created with jQuery in the Windows Azure cloud. In this blog entry, I make no assumptions. I assume that you have never used Windows Azure and I am going to walk through the steps required to host the application in the cloud in agonizing detail. Our application will consist of a single HTML page and a single service. The HTML page will contain jQuery code that invokes the service to retrieve and display set of records. There are five steps that you must complete to host the jQuery application: Sign up for Windows Azure Create a Hosted Service Install the Windows Azure Tools for Visual Studio Create a Windows Azure Cloud Service Deploy the Cloud Service Sign Up for Windows Azure Go to http://www.microsoft.com/windowsazure/ and click the Sign up Now button. Select one of the offers. I selected the Introductory Special offer because it is free and I just wanted to experiment with Windows Azure for the purposes of this blog entry.     To sign up, you will need a Windows Live ID and you will need to enter a credit card number. After you finish the sign up process, you will receive an email that explains how to activate your account. Accessing the Developer Portal After you create your account and your account is activated, you can access the Windows Azure developer portal by visiting the following URL: http://windows.azure.com/ When you first visit the developer portal, you will see the one project that you created when you set up your Windows Azure account (In a fit of creativity, I named my project StephenWalther).     Creating a New Windows Azure Hosted Service Before you can host an application in the cloud, you must first add a hosted service to your project. Click your project on the summary page and click the New Service link. You are presented with the option of creating either a new Storage Account or a new Hosted Services.     Because we have code that we want to run in the cloud – the WCF Service -- we want to select the Hosted Services option. After you select this option, you must provide a name and description for your service. This information is used on the developer portal so you can distinguish your services.     When you create a new hosted service, you must enter a unique name for your service (I selected jQueryApp) and you must select a region for this service (I selected Anywhere US). Click the Create button to create the new hosted service.   Install the Windows Azure Tools for Visual Studio We’ll use Visual Studio to create our jQuery project. Before you can use Visual Studio with Windows Azure, you must first install the Windows Azure Tools for Visual Studio. Go to http://www.microsoft.com/windowsazure/ and click the Get Tools and SDK button. The Windows Azure Tools for Visual Studio works with both Visual Studio 2008 and Visual Studio 2010.   Installation of the Windows Azure Tools for Visual Studio is painless. You just need to check some agreement checkboxes and click the Next button a few times and installation will begin:   Creating a Windows Azure Application After you install the Windows Azure Tools for Visual Studio, you can choose to create a Windows Azure Cloud Service by selecting the menu option File, New Project and selecting the Windows Azure Cloud Service project template. I named my new Cloud Service with the name jQueryApp.     Next, you need to select the type of Cloud Service project that you want to create from the New Cloud Service Project dialog.   I selected the C# ASP.NET Web Role option. Alternatively, I could have picked the ASP.NET MVC 2 Web Role option if I wanted to use jQuery with ASP.NET MVC or even the CGI Web Role option if I wanted to use jQuery with PHP. After you complete these steps, you end up with two projects in your Visual Studio solution. The project named WebRole1 represents your ASP.NET application and we will use this project to create our jQuery application. Creating the jQuery Application in the Cloud We are now ready to create the jQuery application. We’ll create a super simple application that displays a list of records retrieved from a WCF service (hosted in the cloud). Create a new page in the WebRole1 project named Default.htm and add the following code: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Products</title> <style type="text/css"> #productContainer div { border:solid 1px black; padding:5px; margin:5px; } </style> </head> <body> <h1>Product Catalog</h1> <div id="productContainer"></div> <script id="productTemplate" type="text/html"> <div> Name: {{= name }} <br /> Price: {{= price }} </div> </script> <script src="Scripts/jquery-1.4.2.js" type="text/javascript"></script> <script src="Scripts/jquery.tmpl.js" type="text/javascript"></script> <script type="text/javascript"> var products = [ {name:"Milk", price:4.55}, {name:"Yogurt", price:2.99}, {name:"Steak", price:23.44} ]; $("#productTemplate").render(products).appendTo("#productContainer"); </script> </body> </html> The jQuery code in this page simply displays a list of products by using a template. I am using a jQuery template to format each product. You can learn more about using jQuery templates by reading the following blog entry by Scott Guthrie: http://weblogs.asp.net/scottgu/archive/2010/05/07/jquery-templates-and-data-linking-and-microsoft-contributing-to-jquery.aspx You can test whether the Default.htm page is working correctly by running your application (hit the F5 key). The first time that you run your application, a database is set up on your local machine to simulate cloud storage. You will see the following dialog: If the Default.htm page works as expected, you should see the list of three products: Adding an Ajax-Enabled WCF Service In the previous section, we created a simple jQuery application that displays an array by using a template. The application is a little too simple because the data is static. In this section, we’ll modify the page so that the data is retrieved from a WCF service instead of an array. First, we need to add a new Ajax-enabled WCF Service to the WebRole1 project. Select the menu option Project, Add New Item and select the Ajax-enabled WCF Service project item. Name the new service ProductService.svc. Modify the service so that it returns a static collection of products. The final code for the ProductService.svc should look like this: using System.Collections.Generic; using System.ServiceModel; using System.ServiceModel.Activation; namespace WebRole1 { public class Product { public string name { get; set; } public decimal price { get; set; } } [ServiceContract(Namespace = "")] [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)] public class ProductService { [OperationContract] public IList<Product> SelectProducts() { var products = new List<Product>(); products.Add(new Product {name="Milk", price=4.55m} ); products.Add(new Product { name = "Yogurt", price = 2.99m }); products.Add(new Product { name = "Steak", price = 23.44m }); return products; } } }   In real life, you would want to retrieve the list of products from storage instead of a static array. We are being lazy here. Next you need to modify the Default.htm page to use the ProductService.svc. The jQuery script in the following updated Default.htm page makes an Ajax call to the WCF service. The data retrieved from the ProductService.svc is displayed in the client template. <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Products</title> <style type="text/css"> #productContainer div { border:solid 1px black; padding:5px; margin:5px; } </style> </head> <body> <h1>Product Catalog</h1> <div id="productContainer"></div> <script id="productTemplate" type="text/html"> <div> Name: {{= name }} <br /> Price: {{= price }} </div> </script> <script src="Scripts/jquery-1.4.2.js" type="text/javascript"></script> <script src="Scripts/jquery.tmpl.js" type="text/javascript"></script> <script type="text/javascript"> $.post("ProductService.svc/SelectProducts", function (results) { var products = results["d"]; $("#productTemplate").render(products).appendTo("#productContainer"); }); </script> </body> </html>   Deploying the jQuery Application to the Cloud Now that we have created our jQuery application, we are ready to deploy our application to the cloud so that the whole world can use it. Right-click your jQueryApp project in the Solution Explorer window and select the Publish menu option. When you select publish, your application and your application configuration information is packaged up into two files named jQueryApp.cspkg and ServiceConfiguration.cscfg. Visual Studio opens the directory that contains the two files. In order to deploy these files to the Windows Azure cloud, you must upload these files yourself. Return to the Windows Azure Developers Portal at the following address: http://windows.azure.com/ Select your project and select the jQueryApp service. You will see a mysterious cube. Click the Deploy button to upload your application.   Next, you need to browse to the location on your hard drive where the jQueryApp project was published and select both the packaged application and the packaged application configuration file. Supply the deployment with a name and click the Deploy button.     While your application is in the process of being deployed, you can view a progress bar.     Running the jQuery Application in the Cloud Finally, you can run your jQuery application in the cloud by clicking the Run button.   It might take several minutes for your application to initialize (go grab a coffee). After WebRole1 finishes initializing, you can navigate to the following URL to view your live jQuery application in the cloud: http://jqueryapp.cloudapp.net/default.htm The page is hosted on the Windows Azure cloud and the WCF service executes every time that you request the page to retrieve the list of products. Summary Because we started from scratch, we needed to complete several steps to create and deploy our jQuery application to the Windows Azure cloud. We needed to create a Windows Azure account, create a hosted service, install the Windows Azure Tools for Visual Studio, create the jQuery application, and deploy it to the cloud. Now that we have finished this process once, modifying our existing cloud application or creating a new cloud application is easy. jQuery and Windows Azure work nicely together. We can take advantage of jQuery to build applications that run in the browser and we can take advantage of Windows Azure to host the backend services required by our jQuery application. The big benefit of Windows Azure is that it enables us to scale. If, all of the sudden, our jQuery application explodes in popularity, Windows Azure enables us to easily scale up to meet the demand. We can handle anything that the Internet might throw at us.

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• WPF resource merged to Application.Resources but not resolved at runtime

  - by arconaut

  I have a brush that is part of a ResourceDictionary that is merged to Application.Resources. But for some reason it's not resolved at runtime when a style is being applied to one of the controls. However, if I call Application.Current.FindResource("BrushName") from the Immediate Window at the time when exception is thrown, the resource is found. Am I missing something? Isn't WPF supposed to try to look for the resource in the app's resources? UPDATE The application is quite big, so I can't post all actual code but here's the way the resources are merged and used: Brushes.xaml <ResourceDictionary ...> <SolidColorBrush x:Key="BrushName" Color="#12345678" /> <\ResourceDictionary> SomeStyles.xaml <ResourceDictionary ...> <Style x:Key="SomeStyle"> <Setter Property="SomeProperty" Value="{StaticResource BrushName}" /> </Style> </ResourceDictionary> App.xaml <Application ...> <Application.Resources> <ResourceDictionary> <ResourceDictionary.MergedDictionaries> <ResourceDictionary Source="Brushes.xaml" /> <ResourceDictionary Source="SomeStyles.xaml" /> </ResourceDictionary.MergedDictionaries> </ResourceDictionary> </Application.Resources> </Application ...> And then some control might use the style using the resource like this: ... Style={StaticResource SomeStyle} ...

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• Preloading Winforms using a Stack and Hidden Form

  - by msarchet

  I am currently working on a project where we have a couple very control heavy user controls that are being used inside a MDI Controller. This is a Line of Business app and it is very data driven. The problem that we were facing was the aforementioned controls would load very very slowly, we dipped our toes into the waters of multi-threading for the control loading but that was not a solution for a plethora of reasons. Our solution to increasing the performance of the controls ended up being to 'pre-load' the forms onto a hidden window, create a stack of the existing forms, and pop off of the stack as the user requested a form. Now the current issue that I'm seeing that will arise as we push this 'fix' out to our testers, and the ultimately our users is this: Currently the 'hidden' window that contains the preloaded forms is visible in task manager, and can be shut down thus causing all of the controls to be lost. Then you have to create them on the fly losing the performance increase. Secondly, when the user uses up the stack we lose the performance increase (current solution to this is discussed below). For the first problem, is there a way to hide this window from task manager, perhaps by creating a parent form that encapsulates both the main form for the program and the hidden form? Our current solution to the second problem is to have an inactivity timer that when it fires checks the stacks for the forms, and loads a new form onto the stack if it isn't full. However this still has the potential of causing a hang in the UI while it creates the forms. A possible solutions for this would be to put 'used' forms back onto the stack, but I feel like there may be a better way. EDIT: For control design clarification From the comments I have realized there is a lack of clarity on what exactly the control is doing. Here is a detailed explanation of one of the controls. I have defined for this control loading time as the time it takes from when a user performs an action that would open a control, until the time a control is accessible to be edited. The control is for entering Prescriptions for a patient in the system, it has about 5 tabbed groups with a total of about 180 controls. The user selects to open a new Prescription control from inside the main program, this control is loaded into the MDI Child area of the Main Form (which is a DevExpress Ribbon Control). From the time the user clicks New (or loads an existing record) until the control is visible. The list of actions that happens in the program is this: The stack is checked for the existence of a control. If the control exists it is popped off of the stack. The control is rendered on screen. This is what takes 2 seconds The control then is populated with a blank object, or with existing data. The control is ready to use. The average percentage of loading time, across about 10 different machines, with different hardware the control rendering takes about 85 - 95 percent of the control loading time. Without using the stack the control takes about 2 seconds to load, with the stack it takes about .8 seconds, this second time is acceptable. I have looked at Henry's link and I had previously already implemented the applicable suggestions. Again I re-iterate my question as What is the best method to move controls to and from the stack with as little UI interruption as possible?

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• Question about SQL Server HierarchyID depth-first performance

  - by AndalusianCat

  I am trying to implement hierarchyID in a table (dbo.[Message]) containing roughly 50,000 rows (will grow substantially in the future). However it takes 30-40 seconds to retrieve about 25 results. The root node is a filler in order to provide uniqueness, therefor every subsequent row is a child of that dummy row. I need to be able to traverse the table depth-first and have made the hierarchyID column (dbo.[Message].MessageID) the clustering primary key, have also added a computed smallint (dbo.[Message].Hierarchy) which stores the level of the node. Usage: A .Net application passes through a hierarchyID value into the database and I want to be able to retrieve all (if any) children AND parents of that node (besides the root, as it is filler). A simplified version of the query I am using: @MessageID hierarchyID /* passed in from application */ SELECT m.MessageID, m.MessageComment FROM dbo.[Message] as m WHERE m.Messageid.IsDescendantOf(@MessageID.GetAncestor((@MessageID.GetLevel()-1))) = 1 ORDER BY m.MessageID From what I understand, the index should be detected automatically without a hint. From searching forums I have seen people utilizing index hints, at least in the case of breadth-first indexes, as apparently CLR calls may be opaque to the query optimizer. I have spent the past few days trying to find a solution for this issue, but to no avail. I would greatly appreciate any assistance, and as this is my first post, I apologize in advance if this would be considered a 'noobish' question, I have read the MS documentation and searched countless forums, but have not came across a succinct description of the specific issue.

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• Application Installation error Blackberry

  - by tek3

  Hi all, I have an application of mine on AppStore. But one user is complaining that he can not install the application on his device(Curve 8900) and it's giving error "Error starting AppName $28NonTouch$29: Module 'AppName $28NonTouch$29-2' has verification errors." Now how come it is possible that other's users are able to download properly while one user is getting this error. I downloaded the application from the appstore and its working perfectly. And when this user tries to install the application through Desktop Manager he is getting error "No additional applications can be found. Your file may contain applications that already exist in the application list, are not compatible for your device, or have errors." When i tried to stimulate the issue here by installing the application through desktop manager i am able to install it properly without any error messages. Can anyone suggest me ,what might be causing this issue.?? Is there any kind of version mismatch?? My application is compiled usiong jdk 4.5. Any help in this regard will be greatly appreciated. Kindly help,Its urgent.. Thanx in advance."

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• Advice on designing and building distributed application to track vehicles

  - by dario-g

  I'm working on application for tracking vehicles. There will be about 10k or more vehicles. Each will be sending ~250bytes in each minute. Data contains gps location and everything from CAN Bus (every data that we can read from vehicle computer and dashboard). Data are sent by GSM/GPRS (using UDP protocol). Estimated rows with this data per day is ~2000k. I see there 3 main blocks. 1. Multithreaded Socket Server (MSS) - I have it. MSS stores received data to the queue (using NServiceBus). 2. Rule Processor Server (RPS) - this is core of this system. This block is responsible for parsing received data, storing in the database, processing rules, sending messages to Notifier Server (this will be sending e-mails/sms texts). Rule example. As I said between received bytes there will be information about current speed. When speed will be above 120 then: show alert in web application for specified users, send e-mail, send sms text. (There can be more than one instance of RPS). 3. Web application - allows reporting and defining rules by users, monitoring alerts, etc. I'm looking for advice how to design communication between RPS and Web application. Some questions: - Should Web application and RPS have separated databases or one central database will be enough? I have one domain model in web application. If there will be one central database then can I use the same model (objects) on RPS? So, how to send changed rules to RPS? I try to decouple this blocks as much as possible. I'm planning to create different instance of application for each client (each client will have separated database). One client will be have 10k vehicles, others only 100 vehicles.

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• Designing secure consumer blackberry application

  - by Kiran Kuppa

  I am evaluating a requirement for a consumer blackberry application that places high premium on security of user's data. Seems like it is an insurance company. Here are my ideas on how I could go about it. I am sure this would be useful for others who are looking for similar stuff Force the user to use device password. (I am guessing that this would be possible - though not checked it yet). Application can request notifications when the device is about to be locked and just after it has been unlocked. Encryption of application specific data can be managed at those times. Application data would be encrypted with user's password. User's credentials would be encrypted with device password. Remote backup of the data could be done over HTTPS (any better ideas are appreciated) Questions: What if the user forgets his device password. If the user forgets his application password, what is the best and secure way to reset the password? If the user losses the phone, remote backup must be done and the application data must be cleaned up. I have some ideas on how to achieve (3) and shall share them. There must be an off-line verification of the user's identity and the administrator must provide a channel using which the user must be able to send command to the device to perform the wiping of application data. The idea is that the user is ALWAYS in control of his data. Without the user's consent, even the admin must not be able to do activities such as cleaning up the data. In the above scheme of things, it appears as if the user's password need not be sent over the air to server. Am I correct? Thanks, --Kiran Kumar

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• Aggregate Pattern and Performance Issues

  - by Mosh

  Hello, I have read about the Aggregate Pattern but I'm confused about something here. The pattern states that all the objects belonging to the aggregate should be accessed via the Aggregate Root, and not directly. And I'm assuming that is the reason why they say you should have a single Repository per Aggregate. But I think this adds a noticeable overhead to the application. For example, in a typical Web-based application, what if I want to get an object belonging to an aggregate (which is NOT the aggregate root)? I'll have to call Repository.GetAggregateRootObject(), which loads the aggregate root and all its child objects, and then iterate through the child objects to find the one I'm looking for. In other words, I'm loading lots of data and throwing them out except the particular object I'm looking for. Is there something I'm missing here? PS: I know some of you may suggest that we can improve performance with Lazy Loading. But that's not what I'm asking here... The aggregate pattern requires that all objects belonging to the aggregate be loaded together, so we can enforce business rules.

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• Android application listed as compatible with Sony Xperia S but still filtered from google play

  - by mlidal

  I have published an Android application and some users are complaining that it is listed as not compatible with Sony Xperia S. According to the developer console Xperia S (LT26i) is listed as compatible. Do anyone know of any reason why the app is still filtered from google play? I have seen people reporting problems with big apk files. This app is about 20Mb in size, with the largest file being 14Mb. Quite a bit but not enough to cause problems I think... Here is the output from aapt dump badging: package: name='no.bouvet.nrkut' versionCode='4' versionName='1.0' sdkVersion:'4' targetSdkVersion:'13' uses-permission:'android.permission.ACCESS_FINE_LOCATION' uses-permission:'android.permission.ACCESS_COARSE_LOCATION' uses-permission:'android.permission.ACCESS_WIFI_STATE' uses-permission:'android.permission.ACCESS_NETWORK_STATE' uses-permission:'android.permission.INTERNET' uses-permission:'android.permission.WRITE_EXTERNAL_STORAGE' application-label:'UT.no' application-icon-120:'res/drawable-ldpi/utno_launcher.png' application-icon-160:'res/drawable-mdpi/utno_launcher.png' application-icon-240:'res/drawable-hdpi/utno_launcher.png' application-icon-320:'res/drawable-xhdpi/utno_launcher.png' application: label='UT.no' icon='res/drawable-mdpi/utno_launcher.png' launchable-activity: name='no.bouvet.nrkut.MainActivity' label='UT.no' icon='' uses-feature:'android.hardware.location' uses-feature:'android.hardware.location.gps' uses-feature:'android.hardware.location.network' uses-feature:'android.hardware.wifi' uses-feature:'android.hardware.touchscreen' uses-feature:'android.hardware.screen.portrait' main other-activities search supports-screens: 'small' 'normal' 'large' 'xlarge' supports-any-density: 'true' locales: '--_--' densities: '120' '160' '240' '320'

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• Random Complete System Unresponsiveness Running Mathematical Functions

  - by Computer Guru

  I have a program that loads a file (anywhere from 10MB to 5GB) a chunk at a time (ReadFile), and for each chunk performs a set of mathematical operations (basically calculates the hash). After calculating the hash, it stores info about the chunk in an STL map (basically <chunkID, hash>) and then writes the chunk itself to another file (WriteFile). That's all it does. This program will cause certain PCs to choke and die. The mouse begins to stutter, the task manager takes 2 min to show, ctrl+alt+del is unresponsive, running programs are slow.... the works. I've done literally everything I can think of to optimize the program, and have triple-checked all objects. What I've done: Tried different (less intensive) hashing algorithms. Switched all allocations to nedmalloc instead of the default new operator Switched from stl::map to unordered_set, found the performance to still be abysmal, so I switched again to Google's dense_hash_map. Converted all objects to store pointers to objects instead of the objects themselves. Caching all Read and Write operations. Instead of reading a 16k chunk of the file and performing the math on it, I read 4MB into a buffer and read 16k chunks from there instead. Same for all write operations - they are coalesced into 4MB blocks before being written to disk. Run extensive profiling with Visual Studio 2010, AMD Code Analyst, and perfmon. Set the thread priority to THREAD_MODE_BACKGROUND_BEGIN Set the thread priority to THREAD_PRIORITY_IDLE Added a Sleep(100) call after every loop. Even after all this, the application still results in a system-wide hang on certain machines under certain circumstances. Perfmon and Process Explorer show minimal CPU usage (with the sleep), no constant reads/writes from disk, few hard pagefaults (and only ~30k pagefaults in the lifetime of the application on a 5GB input file), little virtual memory (never more than 150MB), no leaked handles, no memory leaks. The machines I've tested it on run Windows XP - Windows 7, x86 and x64 versions included. None have less than 2GB RAM, though the problem is always exacerbated under lower memory conditions. I'm at a loss as to what to do next. I don't know what's causing it - I'm torn between CPU or Memory as the culprit. CPU because without the sleep and under different thread priorities the system performances changes noticeably. Memory because there's a huge difference in how often the issue occurs when using unordered_set vs Google's dense_hash_map. What's really weird? Obviously, the NT kernel design is supposed to prevent this sort of behavior from ever occurring (a user-mode application driving the system to this sort of extreme poor performance!?)..... but when I compile the code and run it on OS X or Linux (it's fairly standard C++ throughout) it performs excellently even on poor machines with little RAM and weaker CPUs. What am I supposed to do next? How do I know what the hell it is that Windows is doing behind the scenes that's killing system performance, when all the indicators are that the application itself isn't doing anything extreme? Any advice would be most welcome.

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• Developing cross platform mobile application

  - by sohilv

  More and more mobile platforms are being launched and sdk's are available to developers. There are various mobile platform are available, Android,iOS,Moblin,Windows mobile 7,RIM,symbian,bada,maemo etc. And making of corss platform application is headache for developers. I am searching common thing across the platforms which will help to developers who want to port application to all platforms.Like what is the diff screen resolution, input methods, open gl support etc. please share details that you know for the any of platform . or is there possibilities , by writing code in html (widget type of thing) and load it into native application. I know about the android , in which we can add the web view into application. by calling setContentView(view) Please share the class details where we can add the html view into native application of different type of platforms that you know. Purpose of this thread is share common details across developers. marking as community wiki. Cross platform tools & library XMLVM and iSpectrum (cross compile Java code from an Android app or creating one from scratch Phone Gap (cross platform mobile apps) Titanium (to build native mobile and desktop apps with web technologies) Mono Touch ( C# for iphone ) rhomobile - http://rhomobile.com/ samples are here: http://github.com/rhomobile/rhodes-system-api-samples Sencha Touch - Sencha Touch is a HTML5 mobile app framework that allows you to develop web apps that look and feel native on Apple iOS and Google Android touchscreen devices. http://www.sencha.com/products/touch/ Corona - Iphone/Ipad / Android application cross platform library . Too awesome. http://anscamobile.com/corona/ A guide to port existing Android app to Windows Phone 7 http://windowsphone.interoperabilitybridges.com/articles/windows-phone-7-guide-for-iphone-application-developers

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• How to deploy ClickOnce .Net 3.5 application on 3.0 machine

  - by Buthrakaur

  I have .Net 3.5 SP1 WPF application which I'm successfully deploying to client computers using ClickOnce. Now I got new requirement - one of our clients need to run the application on machines equipped just with .Net 3.0 and it's entirely impossible to upgrade or install anything on the machines. I already tried to run the 3.5 application with some of the 3.5FW DLLs copied to the application directory and it worked without any problems. The only problem at the moment is ClickOnce. I already made it to include the 3.5FW System.*.dll files in list of application files, but it always aborts installation on 3.0 machine with this error message: Unable to install or run the application. The application requires that assembly System.Core Version 3.5.0.0 be installed in the Global Assembly Cache (GAC) first. Please contact your system administrator. I already tried to tweak prerequisites on Publish tab of my project, but no combination solved the issue. What part of ClickOnce is responsible for checking prerequisites? I already tried to deploy using mageui.exe, but the 3.5FW error is still present. What should I do to fore ClickOnce to stop checking any prerequisites at all? The project is created using VS2010.

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• Is there a difference between starting an application from the OS or from adb

  - by aruwen

  I do have a curious error in my application. My app crashes (don't mind the crash, I roughly know why - classloader) when I start the application from the OS directly, then kill it from the background via any Task Killer (this is one of the few ways to reproduce the crash consistently - simulating the OS freeing memory and closing the application) and try to restart it again. The thing is, if I start the application via adb shell using the following command: adb shell am start -a android.intent.action.MAIN -n com.my.packagename/myLaunchActivity I cannot reproduce the crash. So is there any difference in how Android OS calls the application as opposed to the above call? EDIT: added the manifest (just changed names) <?xml version="1.0" ?> <manifest android:versionCode="5" android:versionName="1.05" package="com.my.sample" xmlns:android="http://schemas.android.com/apk/res/android"> <uses-sdk android:minSdkVersion="7"/> <application android:icon="@drawable/square_my_logo" android:label="@string/app_name"> <activity android:label="@string/app_name" android:name="com.my.InfoActivity" android:screenOrientation="landscape"></activity> <activity android:label="@string/app_name" android:name="com.my2.KickStart" android:screenOrientation="landscape"/> <activity android:label="@string/app_name" android:name="com.my2.Launcher" android:screenOrientation="landscape"> <intent-filter> <action android:name="android.intent.action.MAIN"/> <category android:name="android.intent.category.LAUNCHER"/> </intent-filter> </activity> </application> <uses-permission android:name="android.permission.INTERNET"/> <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/></manifest> starting the com.my2.Launcher from the adb shell

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• Why don't I just build the whole web app in Javascript and Javascript HTML Templates?

  - by viatropos

  I'm getting to the point on an app where I need to start caching things, and it got me thinking... In some parts of the app, I render table rows (jqGrid, slickgrid, etc.) or fancy div rows (like in the New Twitter) by grabbing pure JSON and running it through something like Mustache, jquery.tmpl, etc. In other parts of the app, I just render the info in pure HTML (server-side HAML templates), and if there's searching/paginating, I just go to a new URL and load a new HTML page. Now the problem is in caching and maintainability. On one hand I'm thinking, if everything was built using Javascript HTML Templates, then my app would serve just an HTML layout/shell, and a bunch of JSON. If you look at the Facebook and Twitter HTML source, that's basically what they're doing (95% json/javascript, 5% html). This would make it so my app only needed to cache JSON (pages, actions, and/or records). Which means you'd hit the cache no matter if you were some remote api developer accessing a JSON api, or the strait web app. That is, I don't need 2 caches, one for the JSON, one for the HTML. That seems like it'd cut my cache store down in half, and streamline things a little bit. On the other hand, I'm thinking, from what I've seen/experienced, generating static HTML server-side, and caching that, seems to be much better performance wise cross-browser; you get the graphics instantly and don't have to wait that split-second for javascript to render it. StackOverflow seems to do everything in plain HTML, and you can tell... everything appears at once. Notice how though on twitter.com, the page is blank for .5-1 seconds, and the page chunks in: the javascript has to render the json. The downside with this is that, for anything dynamic (like endless scrolling, or grids), I'd have to create javascript templates anyway... so now I have server-side HAML templates, client-side javascript templates, and a lot more to cache. My question is, is there any consensus on how to approach this? What are the benefits and drawbacks from your experience of mixing the two versus going 100% with one over the other? Update: Some reasons that factor into why I haven't yet made the decision to go with 100% javascript templating are: Performance. Haven't formally tested, but from what I've seen, raw html renders faster and more fluidly than javascript-generated html cross-browser. Plus, I'm not sure how mobile devices handle dynamic html performance-wise. Testing. I have a lot of integration tests that work well with static HTML, so switching to javascript-only would require 1) more focused pure-javascript testing (jasmine), and 2) integrating javascript into capybara integration tests. This is just a matter of time and work, but it's probably significant. Maintenance. Getting rid of HAML. I love HAML, it's so easy to write, it prints pretty HTML... It makes code clean, it makes maintenance easy. Going with javascript, there's nothing as concise. SEO. I know google handles the ajax /#!/path, but haven't grasped how this will affect other search engines and how older browsers handle it. Seems like it'd require a significant setup.

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• Using application roles with DataReader

  - by Shahar

  I have an application that should use an application role from the database. I'm trying to make this work with queries that are actually run using Subsonic (2). To do this, I created my own DataProvider, which inherits from Subsonic's SqlDataProvider. It overrides the CreateConnection function, and calls sp_appsetrole to set the application role after the connection is created. This part works fine, and I'm able to get data using the application role. The problem comes when I try to unset the application role. I couldn't find any place in the code where my provider is called after the query is done, so I tried to add my own, by changing SubSonic code. The problem is that Subsonic uses a data reader. It loads data from the data reader, and then closes it. If I unset the application role before the data reader is closed, I get an error saying: There is already an open DataReader associated with this Command which must be closed first. If I unset the application role after the data reader is closed, I get an error saying ExecuteNonQuery requires an open and available Connection. The connection's current state is closed. I can't seem to find a way to close the data reader without closing the connection.

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• Very strange Application.ThreadException behaviour.

  - by Brann

  I'm using the Application.ThreadException event to handle and log unexpected exceptions in my winforms application. Now, somewhere in my application, I've got the following code (or rather something equivalent, but this dummy code is enough to reproduce my issue) : try { throw new NullReferenceException("test"); } catch (Exception ex) { throw new Exception("test2", ex); } I'm clearly expecting my Application_ThreadException handler to be passed the "test2" exception, but this is not always the case. Typically, if another thread marshals my code to the UI, my handler receives the "test" exception, exactly as if I hadn't caught "test" at all. Here is a short sample reproducing this behavior. I have omitted the designer's code. static class Program { [STAThread] static void Main() { Application.ThreadException += new System.Threading.ThreadExceptionEventHandler(Application_ThreadException); Application.EnableVisualStyles(); Application.SetCompatibleTextRenderingDefault(false); Application.Run(new Form1()); } static void Application_ThreadException(object sender, System.Threading.ThreadExceptionEventArgs e) { Console.WriteLine(e.Exception.Message); } } public partial class Form1 : Form { public Form1() { InitializeComponent(); button1.Click+=new EventHandler(button1_Click); System.Threading.Thread t = new System.Threading.Thread(new System.Threading.ThreadStart(ThrowEx)); t.Start(); } private void button1_Click(object sender, EventArgs e) { try { throw new NullReferenceException("test"); } catch (Exception ex) { throw new Exception("test2", ex); } } void ThrowEx() { this.BeginInvoke(new EventHandler(button1_Click)); } } The output of this program on my computer is : test ... here I click button1 test2 I've reproduced this on .net 2.0,3.5 and 4.0. Does someone have a logical explanation ?

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• data ownership and performance

  - by Ami

  We're designing a new application and we ran into some architectural question when thinking about data ownership. we broke down the system into components, for example Customer and Order. each of this component/module is responsible for a specific business domain, i.e. Customer deals with CRUD of customers and business process centered around customers (Register a n new customer, block customer account, etc.). each module is the owner of a set of database tables, and only that module may access them. if another module needs data that is owned by another module, it retrieves it by requesting it from that module. so far so good, the question is how to deal with scenarios such as a report that needs to show all the customers and for each customer all his orders? in such a case we need to get all the customers from the Customer module, iterate over them and for each one get all the data from the Order module. performance won't be good...obviously it would be much better to have a stored proc join customers table and orders table, but that would also mean direct access to the data that is owned by another module, creating coupling and dependencies that we wish to avoid. this is a simplified example, we're dealing with an enterprise application with a lot of business entities and relationships, and my goal is to keep it clean and as loosely coupled as possible. I foresee in the future many changes to the data scheme, and possibly splitting the system into several completely separate systems. I wish to have a design that would allow this to be done in a relatively easy way. Thanks!

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• AppleScript: open frontmost file with another application

  - by jacobianism

  I'd like to write an AppleScript program to do the following (Automator would be fine too): I want to open the current active TextMate file (possibly there are several tabs open and other windows) with the application Transmit 2. (This will upload the file over FTP using Transmit's DockSend feature.) Here I've used a specific application (TextMate) but ideally I'd like it to work for any file currently active in any application. Ultimately I will assign a keyboard shortcut to run it. Here's what I have so far: tell application (path to frontmost application as text) set p to path of document 1 end tell tell application "Finder" open POSIX file p using "Transmit 2" end tell I've tried many variants of this and nothing works. EDIT: I have found this page: http://wiki.macromates.com/Main/Howtos and someone has made exactly the script I'm looking for: tell application "Transmit" to open POSIX file "$TM_FILEPATH" This is for Transmit [not 2] and I think for TextMate pre v2. I get the error (when using Transmit 2): Transmit 2 got an error: AppleEvent handler failed. One of the updates to v2 has broken it (not sure which one).

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• How do I change the application background color at run-time in a Flex 3.5 application?

  - by Adam Tuttle

  I have a Flex 3.5 application that will serve multiple purposes, and as part of the visual changes that I'd like to make to indicate which mode the application is in, I want to change its background color. Currently, the application tag looks like this: <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" xmlns:com="ventures.view.component.*" xmlns:views="ventures.view.*" layout="absolute" preinitialize="onPreInitialize()" creationComplete="onCreationComplete()" applicationComplete="onApplicationComplete()" click="onClick(event)" enabled="{(!chainController.generalLocked)}" backgroundGradientColors="[0xFFFFFF, 0xFFFFFF]" > I've tried using a binding, for both the backgroundColor and backgroundGradientColors attributes: <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" ... backgroundColor="{app_background_color}" > —and— <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" ... backgroundGradientColors="{app_background_color}" > but for the former binding is not allowed, and for the latter there is a warning that: Data binding will not be able to detect assignments to "app_background_color". I also ran across this page which seems to indicate that I could do it with the setStyle() method, but the documentation seems to indicate that this method is only available for components, not the main canvas. I suppose I could wrap everything in a <mx:Canvas></mx:Canvas> specificially for this purpose, but that seems wasteful—like Div-itis in HTML or something. What's the best way to change the main application background color at run-time?

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• Improve WPF Rendering Performance (WrapPanel in ItemsControl)

  - by Wonko the Sane

  Hello All, I have an ItemsSource that appears to have poor performance when adding even a fairly small ObservableCollection to it. The ItemsPanel is a WrapPanel, and the ItemTemplate is essentially a Border containing another Border painted with an ImageBrush. The ItemsControl is wrapped inside a ScrollViewer. After some investigation using WpfPerf, it would appear that most of the "what the heck is it doing?" time is spent on WrapPanel.Measure after creating the collection that is being bound. As I've mentioned, it's a fairly small collection - generally less than 100 items. If nothing else, I'd like to be able to put a "Please Wait" on the screen (during the collection creation portion as well), but I am not sure how to know when the rendering is complete. Any thoughts would be greatly appreciated! Thanks, wTs

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