context switch - Page 204

Why i cannot get the frame of a UIView in order to move it? The view is defined.

- by Jann

I am creating a nav-based app with a view that floats at the bottom of the screen (Alpha .7 most of the time). I create it like this... // stuff to create the tabbar/nav bar. // THIS ALL WORKS... // then add it to subview. [window addSubview:tabBarController.view]; // need this last line to display the window (and tab bar controller) [window makeKeyAndVisible]; // Okay, here is the code i am using to create a grey-ish strip exactly `zlocationAccuracyHeight` pixels high at `zlocationAccuracyVerticalStartPoint` starting point vertically. CGRect locationManagerAccuracyUIViewFrame = CGRectMake(0,zlocationAccuracyVerticalStartPoint,[[UIScreen mainScreen] bounds].size.width,zlocationAccuracyHeight); self.locationManagerAccuracyUIView = [[UIView alloc] initWithFrame:locationManagerAccuracyUIViewFrame]; self.locationManagerAccuracyUIView.autoresizingMask = (UIViewAutoresizingFlexibleWidth); self.locationManagerAccuracyUIView.backgroundColor = [UIColor darkGrayColor]; [self.locationManagerAccuracyUIView setAlpha:0]; CGRect locationManagerAccuracyLabelFrame = CGRectMake(0, 0,[[UIScreen mainScreen] bounds].size.width,zlocationAccuracyHeight); locationManagerAccuracyLabel = [[UILabel alloc] initWithFrame:locationManagerAccuracyLabelFrame]; if ([myGizmoClass useLocationServices] == 0) { locationManagerAccuracyLabel.text = @"GPS Accuracy: Using Manual Location"; } else { locationManagerAccuracyLabel.text = @"GPS Accuracy: One Moment Please..."; } locationManagerAccuracyLabel.font = [UIFont boldSystemFontOfSize:12]; locationManagerAccuracyLabel.textAlignment = UITextAlignmentCenter; locationManagerAccuracyLabel.textColor = [UIColor whiteColor]; locationManagerAccuracyLabel.backgroundColor = [UIColor clearColor]; [locationManagerAccuracyLabel setAlpha:0]; [self.locationManagerAccuracyUIView addSubview: locationManagerAccuracyLabel]; [window addSubview: self.locationManagerAccuracyUIView]; this all works (i am not sure about the order i create the uiview in ... meaning i am creating the frame, the view, creating the "accuracy text" and adding that to the view, then adding the uiview as a subview of the window . It works and seems correct in my logic. So, here is the tough part. I have a timer that i am testing with. I am trying to float the uiview up by 30 pix. here is that code: [UIView beginAnimations:nil context:NULL]; [UIView setAnimationDuration:0.3]; CGRect rect = [ self.locationManagerAccuracyUIView frame]; NSLog(@"ORIGIN: %d x %d (%@)\n",rect.origin.x,rect.origin.y,rect); rect.origin.y -= 30; [UIView commitAnimations]; The problem? rect is nill, rect.origin.x and rect.origin.y are both zero. Can anyone tell me why? Here is how i set up self.locationManagerAccuracyUIView in my files: Delegate.h UIView *locationManagerAccuracyUIView; UILabel *locationManagerAccuracyLabel; ... @property (nonatomic, retain) IBOutlet UIView *locationManagerAccuracyUIView; @property (nonatomic, retain) IBOutlet UILabel *locationManagerAccuracyLabel; Delegate.m ... @synthesize locationManagerAccuracyUIView; @synthesize locationManagerAccuracyLabel; ... BTW: Other places in another timer i DO set the alpha to fade in and out and THAT works! So locationManagerAccuracyUIView is valid and defined as a view... For instance: [UIView beginAnimations:nil context:NULL]; [UIView setAnimationDuration:0.5]; [locationManagerAccuracyLabel setAlpha:1]; [UIView commitAnimations]; [UIView beginAnimations:nil context:NULL]; [UIView setAnimationDuration:0.5]; [self.locationManagerAccuracyUIView setAlpha:.7]; [UIView commitAnimations]; ...and it DOES work. Can anyone help me? As an aside: I know, when typing this I used self.locationManagerAccuracyUIView and locationManagerAccuracyUIView interchangeably to see if for some reason that was the issue. It is not. :) Thx

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objective-c Novice - Needs help with global variables and setter method

- by user544006

I am creating a quiz app which has 2 views, MMAppViewController and a subview Level1View. I have declared NSInteger property "theScore" in the MMAppViewController view and have synthesised it. In my Level1View when they answer a correct question the "theScore" int will increase by one. The score has to be a global variable because when you reach so many points it will unlock the next level. For some reason in my switch statement it only lets me use the setTheScore method once. I am getting errors for every other set method in the switch statement. Error: "Duplicate label setTheScore". The statement is in the pushButtonAnswer method: setTheScore: theScore++; Here is my code: #import "Level1View.h" #import "MMAppViewController.h" @implementation Level1View @synthesize answer; @synthesize question; @synthesize userAnswer; @synthesize theScore; @synthesize score; int questionNum=0; NSInteger score=0; NSInteger theScore; BOOL start=FALSE; BOOL optionNum=FALSE; -(IBAction)pushBack{ [self dismissModalViewControllerAnimated:YES]; } -(IBAction)pushButton1{ optionNum=TRUE; labelAnswer.textColor=[UIColor blackColor]; userAnswer=@"1"; [labelAnswer setText:(@"You chose 'A'")]; } -(IBAction)pushButton2{ optionNum=TRUE; labelAnswer.textColor=[UIColor blackColor]; userAnswer=@"2"; [labelAnswer setText:(@"You chose 'B'")]; } -(IBAction)pushButton3{ optionNum=TRUE; labelAnswer.textColor=[UIColor blackColor]; userAnswer=@"3"; [labelAnswer setText:(@"You chose 'C'")]; } -(IBAction)pushButtonAnswer{ labelAnswer.textColor=[UIColor blackColor]; switch (questionNum){ case 1: if(answer==userAnswer && optionNum==TRUE){ labelAnswer.textColor=[UIColor greenColor]; [labelAnswer setText:(@"correct")]; [self hideButtons]; score++; [self setTheScore: theScore++]; } else if(optionNum==FALSE){ [labelAnswer setText:(@"Please choose an answer below:")];} else{ labelAnswer.textColor=[UIColor redColor]; [labelAnswer setText:(@"wrong")];} [self hideButtons]; break; case 2: if(answer==userAnswer && optionNum==TRUE){ labelAnswer.textColor=[UIColor greenColor]; [labelAnswer setText:(@"correct")]; [self hideButtons]; score++; [self setTheScore: theScore++]; } else if(optionNum==FALSE){ [labelAnswer setText:(@"Please choose an answer below:")];} else{ labelAnswer.textColor=[UIColor redColor]; [labelAnswer setText:(@"wrong")]; [self hideButtons];} break; case 3: if(answer==userAnswer && optionNum==TRUE){ labelAnswer.textColor=[UIColor greenColor]; .... And #import "MMAppViewController.h" #import "Level1View.h" @implementation MMAppViewController @synthesize theScore; NSInteger score; -(IBAction)pushLevel1{ Level1View *level1View = [[Level1View alloc] initWithNibName:nil bundle:nil]; [self presentModalViewController:level1View animated:YES]; theScore++; } -(IBAction)pushLevel2{ //Level1View *level1View = [[Level1View alloc] initWithNibName:nil bundle:nil]; //[self presentModalViewController:level1View animated:YES]; NSInteger *temp = Level1View.score; //int theScore=2; [labelChoose setText:[NSString stringWithFormat:@"You scored %i", theScore]]; } Does anyone know why i am getting these errors and if I am coding this correctly?

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PHP Frontpage/Page controller

- by atno

I using the following as Frontpage/Page Controller(s) and it's working ok so far, except two problems I'm facing which as you can see are the $pages array and the switch, which are actually much much longer as the one I've pasted here. Everytime there is a need for a new page controller I have to add it to $pages array and to switch which makes that list very long. How would you overcome this problem and do you see any other improvement on this code? loadLogic() in page controllers it is used to get functions under pages/controllername/logic/function.php. Frontpage Controller - index.php: include 'common/common.php'; if(!isset($_GET['p']) OR $_GET['p'] == ''){ $_GET['p'] = 'home'; header('Location: index.php?p=home'); } $pages = array('home','register','login','logout','page1','page2','page3'); $_GET['p'] = trim($_GET['p']); if(isset($_GET['p'])){ if(in_array($_GET['p'], $pages)){ switch ($_GET['p']) { case 'home': include 'home.php'; break; case 'register': include 'register.php'; break; case 'login': include 'login.php'; break; case 'logout': include 'logout.php'; break; case 'page1': include 'page1.php'; break; case 'page2': include 'page2.php'; break; case 'page3': include 'page3.php'; break; } }else{ echo '404!'; } } Page Controller - {home,register,login,logout,page1,page2,page3}.php: include 'tpl/common/header.php'; contentStart(); if(isset($_SESSION['logged'])){ loadLogic('dashboard'); }else{ loadLogic('nologin'); } //Display login form in logic page instead links // if(!isset($_SESSION['logged'])){ contentEnd(); loadLogic('nologinForm'); }else{ contentEnd(); include'tpl/common/rcol.php'; } include 'tpl/common/footer.php'; function loadLogic(): function loadLogic($logic) { $path = dirname(__DIR__) . '/pages'; $controller = preg_split('/&/',$_SERVER['QUERY_STRING']); $controller = trim($controller[0],"p="); $logicPath = 'logic'; $logic = $logic . '.php'; $err = 0; $logicFullPath = $path.'/'.$controller.'/'.$logicPath.'/'.$logic; if($err == '0'){ include "$logicFullPath"; } } Folder Structure: projectName | ---> common | ---> pages | | | --->home | | | --->register | | | --->login | | | --->logout | | | --->page1 | | | --->page2 | | | --->page3 | ---> tpl | | | ---> common | --> home.php | --> register.php | --> login.php | --> logout.php | --> page1.php | --> page2.php | --> page3.php

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screnshot in android

- by ujjawal

The following is the code I am using to take a screen shot using GLSurfaceView. But I dont know why the onDraw() method in the GLSurfaceView.Renderer Class is not being called. Please if some one can look at the code below and point out what am I doing wrong.`public class MainActivity extends Activity { private GLSurfaceView mGLView; int x,y,w,h; Display disp; /** Called when the activity is first created. */ @Override public void onCreate(Bundle icicle) { super.onCreate(icicle); // ToDo add your GUI initialization code here setContentView(R.layout.main); x=0; y=0; disp = getWindowManager().getDefaultDisplay(); w = disp.getWidth(); h = disp.getHeight(); mGLView = new ClearGLSurfaceView(this); } class ClearGLSurfaceView extends GLSurfaceView { public ClearGLSurfaceView(Context context) { super(context); setDebugFlags(DEBUG_CHECK_GL_ERROR | DEBUG_LOG_GL_CALLS); mRenderer = new ClearRenderer(); setRenderer(mRenderer); } ClearRenderer mRenderer; } class ClearRenderer implements GLSurfaceView.Renderer { public void onSurfaceCreated(GL10 gl, EGLConfig config) { // Do nothing special. } public void onSurfaceChanged(GL10 gl, int w, int h) { //gl.glViewport(0, 0, w, h); } public void onDrawFrame(GL10 gl) { //gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT); int b[]=new int[w*(y+h)]; int bt[]=new int[w*h]; IntBuffer ib=IntBuffer.wrap(b); ib.position(0); gl.glReadPixels(x, 0, w, y+h, GL10.GL_RGBA, GL10.GL_UNSIGNED_BYTE, ib); for(int i=0, k=0; i<h; i++, k++) {//remember, that OpenGL bitmap is incompatible with Android bitmap //and so, some correction need. for(int j=0; j<w; j++) { int pix=b[i*w+j]; int pb=(pix>>16)&0xff; int pr=(pix<<16)&0x00ff0000; int pix1=(pix&0xff00ff00) | pr | pb; bt[(h-k-1)*w+j]=pix1; } } Bitmap bmp = Bitmap.createBitmap(bt, w, h,Bitmap.Config.ARGB_8888); try { File f = new File("/sdcard/testpicture.png"); f.createNewFile(); FileOutputStream fos=new FileOutputStream(f); bmp.compress(CompressFormat.PNG, 100, fos); try { fos.flush(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } try { fos.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch(IOException e) { e.printStackTrace(); } } } } ` Please someone help me out. I have just started learning to work on android.

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"didChangeSection:" NSfetchedResultsController delegate method not being called

- by robenk

I have a standard split view controller, with a detail view and a table view. Pressing a button in the detail view can cause the an object to change its placement in the table view's ordering. This works fine, as long as the resulting ordering change doesn't result in a section being added or removed. I.e. an object can change it's ordering in a section or switch from one section to another. Those ordering changes work correctly without problems. But, if the object tries to move to a section that doesn't exist yet, or is the last object to leave a section (therefore requiring the section its leaving to be removed), then the application crashes. NSFetchedResultsControllerDelegate has methods to handle sections being added and removed that should be called in those cases. But those delegate methods aren't being called for some reason. The code in question, is boilerplate: - (void)controllerWillChangeContent:(NSFetchedResultsController *)controller { NSLog(@"willChangeContent"); [self.tableView beginUpdates]; } - (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type { NSLog(@"didChangeSection"); switch(type) { case NSFetchedResultsChangeInsert: [self.tableView insertSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade]; break; case NSFetchedResultsChangeDelete: [self.tableView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade]; break; } } - (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type newIndexPath:(NSIndexPath *)newIndexPath { NSLog(@"didChangeObject"); UITableView *tableView = self.tableView; switch(type) { case NSFetchedResultsChangeInsert: [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade]; break; case NSFetchedResultsChangeDelete: [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade]; break; case NSFetchedResultsChangeUpdate: [self configureCell:[tableView cellForRowAtIndexPath:indexPath] atIndexPath:indexPath]; break; case NSFetchedResultsChangeMove: [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade]; [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath]withRowAnimation:UITableViewRowAnimationFade]; break; } } - (void)controllerDidChangeContent:(NSFetchedResultsController *)controller { NSLog(@"didChangeContent"); [self.tableView endUpdates]; [detailViewController.reminderView update]; } Starting the application, and then causing the last object to leave a section results in the following output: 2011-01-08 23:40:18.910 Reminders[54647:207] willChangeContent 2011-01-08 23:40:18.912 Reminders[54647:207] didChangeObject 2011-01-08 23:40:18.914 Reminders[54647:207] didChangeContent 2011-01-08 23:40:18.915 Reminders[54647:207] *** Assertion failure in -[UITableView _endCellAnimationsWithContext:], /SourceCache/UIKit_Sim/UIKit-1145.66/UITableView.m:825 2011-01-08 23:40:18.917 Reminders[54647:207] Serious application error. Exception was caught during Core Data change processing: Invalid update: invalid number of sections. The number of sections contained in the table view after the update (5) must be equal to the number of sections contained in the table view before the update (6), plus or minus the number of sections inserted or deleted (0 inserted, 0 deleted). with userInfo (null) As you can see, "willChangeContent", "didChangeObject" (moving the object in question), and "didChangeContent" were all called properly. Based on the Apple's NSFetchedResultsControllerDelegate documentation "didChangeSection" should have been called before "didChangeObject", which would have prevented the exception causing the crash. So I guess the question is how do I assure that didChangeSection gets called? Thanks in advance for any help!

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Create and Share a File (Also a mysterious error)

- by Kirk

My goal is to create a XML file and then send it through the share Intent. I'm able to create a XML file using this code FileOutputStream outputStream = context.openFileOutput(fileName, Context.MODE_WORLD_READABLE); PrintStream printStream = new PrintStream(outputStream); String xml = this.writeXml(); // get XML here printStream.println(xml); printStream.close(); I'm stuck trying to retrieve a Uri to the output file in order to share it. I first tried to access the file by converting the file to a Uri File outFile = context.getFileStreamPath(fileName); return Uri.fromFile(outFile); This returns file:///data/data/com.my.package/files/myfile.xml but I cannot appear to attach this to an email, upload, etc. If I manually check the file length, it's proper and shows there is a reasonable file size. Next I created a content provider and tried to reference the file and it isn't a valid handle to the file. The ContentProvider doesn't ever seem to be called a any point. Uri uri = Uri.parse("content://" + CachedFileProvider.AUTHORITY + "/" + fileName); return uri; This returns content://com.my.package.provider/myfile.xml but I check the file and it's zero length. How do I access files properly? Do I need to create the file with the content provider? If so, how? Update Here is the code I'm using to share. If I select Gmail, it does show as an attachment but when I send it gives an error Couldn't show attachment and the email that arrives has no attachment. public void onClick(View view) { Log.d(TAG, "onClick " + view.getId()); switch (view.getId()) { case R.id.share_cancel: setResult(RESULT_CANCELED, getIntent()); finish(); break; case R.id.share_share: MyXml xml = new MyXml(); Uri uri; try { uri = xml.writeXmlToFile(getApplicationContext(), "myfile.xml"); //uri is "file:///data/data/com.my.package/files/myfile.xml" Log.d(TAG, "Share URI: " + uri.toString() + " path: " + uri.getPath()); File f = new File(uri.getPath()); Log.d(TAG, "File length: " + f.length()); // shows a valid file size Intent shareIntent = new Intent(); shareIntent.setAction(Intent.ACTION_SEND); shareIntent.putExtra(Intent.EXTRA_STREAM, uri); shareIntent.setType("text/plain"); startActivity(Intent.createChooser(shareIntent, "Share")); } catch (FileNotFoundException e) { e.printStackTrace(); } break; } } I noticed that there is an Exception thrown here from inside createChooser(...), but I can't figure out why it's thrown. E/ActivityThread(572): Activity com.android.internal.app.ChooserActivity has leaked IntentReceiver com.android.internal.app.ResolverActivity$1@4148d658 that was originally registered here. Are you missing a call to unregisterReceiver()? I've researched this error and can't find anything obvious. Both of these links suggest that I need to unregister a receiver. Chooser Activity Leak - Android Why does Intent.createChooser() need a BroadcastReceiver and how to implement? I have a receiver setup, but it's for an AlarmManager that is set elsewhere and doesn't require the app to register / unregister. Code for openFile(...) In case it's needed, here is the content provider I've created. public ParcelFileDescriptor openFile(Uri uri, String mode) throws FileNotFoundException { String fileLocation = getContext().getCacheDir() + "/" + uri.getLastPathSegment(); ParcelFileDescriptor pfd = ParcelFileDescriptor.open(new File(fileLocation), ParcelFileDescriptor.MODE_READ_ONLY); return pfd; }

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Iphone: controlling text with delay problem with UIWebView

- by James B.

Hi, I've opted to use UIWebView so I can control the layout of text I've got contained in a local html document in my bundle. I want the text to display within a UIWebView I've got contained within my view. So the text isn't the whole view, just part of it. Everything runs fine, but when the web page loads I get a blank screen for a second before the text appears. This looks really bad. can anyone give me an example of how to stop this happening? I'm assuming I have to somehow hide the web view until it has fully loaded? Could someone one tell me how to do this? At the moment I'm calling my code through the viewDidLoad like this: [myUIWebView loadRequest: [NSURLRequest requestWithURL:[NSURL fileURLWithPath:[[NSBundle mainBundle]pathForResource:@"localwebpage" ofType:@"html"] isDirectory:NO]]]; Any help is much appreciated. I've read round a few forums and not seen a good answer to this question, and it seems like it recurs a lot as an issue for beginners like myself. Thanks for taking the time to read this post! UPDATED info Thanks for your response. The suggestions below solves the problem but creates a new one for me as now when my view loads it is totally hidden until I click on my toggle switch. to understand this it's maybe most helpful if I post all my code. Before this though let me explain the setup of my view. I've got a standard view within which I've also got two web views, one on top of the other. each web view contains different text with different styling. the user flicks between views using a toggle switch, which hides/reveals the web views. I'm using the web views because I want to control the style/layout of the text. Below is my full .m code, I can't figure out where it's going wrong. My web views are called oxford & harvard I'm sure its something to do with how/when I'm hiding/revealing views. I've played around with this but can't seem to get it right. Maybe my approach is wrong. A bit of advice ironing this out would be really appreciated: @implementation ReferenceViewController @synthesize oxford; @synthesize harvard; // Implement viewDidLoad to do additional setup after loading the view, typically from a nib. - (void)viewDidLoad { [super viewDidLoad]; [oxford loadRequest: [NSURLRequest requestWithURL:[NSURL fileURLWithPath:[[NSBundle mainBundle]pathForResource:@"Oxford" ofType:@"html"] isDirectory:NO]]]; [harvard loadRequest: [NSURLRequest requestWithURL:[NSURL fileURLWithPath:[[NSBundle mainBundle]pathForResource:@"Harvard" ofType:@"html"] isDirectory:NO]]]; [oxford setHidden:YES]; [harvard setHidden:YES]; } - (void)webViewDidFinishLoad:(UIWebView *)webView { if([webView hidden]) { [oxford setHidden:NO]; [harvard setHidden:NO]; } } //Toggle controls for toggle switch in UIView to swap between webviews - (IBAction)toggleControls:(id)sender { if ([sender selectedSegmentIndex] == kSwitchesSegmentIndex) { oxford.hidden = NO; harvard.hidden = YES; } else { oxford.hidden = YES; harvard.hidden = NO; } } - (void)didReceiveMemoryWarning { // Releases the view if it doesn't have a superview. [super didReceiveMemoryWarning]; // Release any cached data, images, etc that aren't in use. } - (void)viewDidUnload { [super viewDidUnload]; // Release any retained subviews of the main view. // e.g. self.myOutlet = nil; } - (void)dealloc { [super dealloc]; [oxford release]; [harvard release]; } @end

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How can I modify my Shunting-Yard Algorithm so it accepts unary operators?

- by KingNestor

I've been working on implementing the Shunting-Yard Algorithm in JavaScript for class. Here is my work so far: var userInput = prompt("Enter in a mathematical expression:"); var postFix = InfixToPostfix(userInput); var result = EvaluateExpression(postFix); document.write("Infix: " + userInput + "<br/>"); document.write("Postfix (RPN): " + postFix + "<br/>"); document.write("Result: " + result + "<br/>"); function EvaluateExpression(expression) { var tokens = expression.split(/([0-9]+|[*+-\/()])/); var evalStack = []; while (tokens.length != 0) { var currentToken = tokens.shift(); if (isNumber(currentToken)) { evalStack.push(currentToken); } else if (isOperator(currentToken)) { var operand1 = evalStack.pop(); var operand2 = evalStack.pop(); var result = PerformOperation(parseInt(operand1), parseInt(operand2), currentToken); evalStack.push(result); } } return evalStack.pop(); } function PerformOperation(operand1, operand2, operator) { switch(operator) { case '+': return operand1 + operand2; case '-': return operand1 - operand2; case '*': return operand1 * operand2; case '/': return operand1 / operand2; default: return; } } function InfixToPostfix(expression) { var tokens = expression.split(/([0-9]+|[*+-\/()])/); var outputQueue = []; var operatorStack = []; while (tokens.length != 0) { var currentToken = tokens.shift(); if (isNumber(currentToken)) { outputQueue.push(currentToken); } else if (isOperator(currentToken)) { while ((getAssociativity(currentToken) == 'left' && getPrecedence(currentToken) <= getPrecedence(operatorStack[operatorStack.length-1])) || (getAssociativity(currentToken) == 'right' && getPrecedence(currentToken) < getPrecedence(operatorStack[operatorStack.length-1]))) { outputQueue.push(operatorStack.pop()) } operatorStack.push(currentToken); } else if (currentToken == '(') { operatorStack.push(currentToken); } else if (currentToken == ')') { while (operatorStack[operatorStack.length-1] != '(') { if (operatorStack.length == 0) throw("Parenthesis balancing error! Shame on you!"); outputQueue.push(operatorStack.pop()); } operatorStack.pop(); } } while (operatorStack.length != 0) { if (!operatorStack[operatorStack.length-1].match(/([()])/)) outputQueue.push(operatorStack.pop()); else throw("Parenthesis balancing error! Shame on you!"); } return outputQueue.join(" "); } function isOperator(token) { if (!token.match(/([*+-\/])/)) return false; else return true; } function isNumber(token) { if (!token.match(/([0-9]+)/)) return false; else return true; } function getPrecedence(token) { switch (token) { case '^': return 9; case '*': case '/': case '%': return 8; case '+': case '-': return 6; default: return -1; } } function getAssociativity(token) { switch(token) { case '+': case '-': case '*': case '/': return 'left'; case '^': return 'right'; } } It works fine so far. If I give it: ((5+3) * 8) It will output: Infix: ((5+3) * 8) Postfix (RPN): 5 3 + 8 * Result: 64 However, I'm struggling with implementing the unary operators so I could do something like: ((-5+3) * 8) What would be the best way to implement unary operators (negation, etc)? Also, does anyone have any suggestions for handling floating point numbers as well? One last thing, if anyone sees me doing anything weird in JavaScript let me know. This is my first JavaScript program and I'm not used to it yet.

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Resolving a Forward Declaration Issue Involving a State Machine in C++

- by hypersonicninja

I've recently returned to C++ development after a hiatus, and have a question regarding implementation of the State Design Pattern. I'm using the vanilla pattern, exactly as per the GoF book. My problem is that the state machine itself is based on some hardware used as part of an embedded system - so the design is fixed and can't be changed. This results in a circular dependency between two of the states (in particular), and I'm trying to resolve this. Here's the simplified code (note that I tried to resolve this by using headers as usual but still had problems - I've omitted them in this code snippet): #include <iostream> #include <memory> using namespace std; class Context { public: friend class State; Context() { } private: State* m_state; }; class State { public: State() { } virtual void Trigger1() = 0; virtual void Trigger2() = 0; }; class LLT : public State { public: LLT() { } void Trigger1() { new DH(); } void Trigger2() { new DL(); } }; class ALL : public State { public: ALL() { } void Trigger1() { new LLT(); } void Trigger2() { new DH(); } }; // DL needs to 'know' about DH. class DL : public State { public: DL() { } void Trigger1() { new ALL(); } void Trigger2() { new DH(); } }; class HLT : public State { public: HLT() { } void Trigger1() { new DH(); } void Trigger2() { new DL(); } }; class AHL : public State { public: AHL() { } void Trigger1() { new DH(); } void Trigger2() { new HLT(); } }; // DH needs to 'know' about DL. class DH : public State { public: DH () { } void Trigger1() { new AHL(); } void Trigger2() { new DL(); } }; int main() { auto_ptr<LLT> llt (new LLT); auto_ptr<ALL> all (new ALL); auto_ptr<DL> dl (new DL); auto_ptr<HLT> hlt (new HLT); auto_ptr<AHL> ahl (new AHL); auto_ptr<DH> dh (new DH); return 0; } The problem is basically that in the State Pattern, state transitions are made by invoking the the ChangeState method in the Context class, which invokes the constructor of the next state. Because of the circular dependency, I can't invoke the constructor because it's not possible to pre-define both of the constructors of the 'problem' states. I had a look at this article, and the template method which seemed to be the ideal solution - but it doesn't compile and my knowledge of templates is a rather limited... The other idea I had is to try and introduce a Helper class to the subclassed states, via multiple inheritance, to see if it's possible to specify the base class's constructor and have a reference to the state subclasse's constructor. But I think that was rather ambitious... Finally, would a direct implmentation of the Factory Method Design Pattern be the best way to resolve the entire problem?

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Possible iphone animation timing/rendering bug?

- by David

Hi all, I have been working on an iphone apps for several weeks. Now I encounter an animation problem that I can't figure out how to resolve. Mayhbe you can help. Here is the details (a little long, bear with me): Basically the effect I want to achieve is, when user click a button, a loading view pops up, hiding the whole screen; and then the apps does a lot of heavy computation, which takes a few seconds. Once the computation is done, soem result views (something likes checkers on a checker board) are rendered under the loading view. Once all result views are rendered, I used animation animation to remove the loading view nand show the result views to the user. Here is what I do: when user click a button, run this code: [UIView beginAnimations:nil context:nil]; [UIView setAnimationDuration:1.0]; [UIView setAnimationBeginsFromCurrentState:YES]; [UIView setAnimationTransition:UIViewAnimationTransitionCurlDown forView:self.view cache:YES]; [UIView setAnimationDelegate:self]; [UIView setAnimationDidStopSelector:@selector(loadingViewInserted:finished:context:)]; // use a really high index number so it will always on top [self.view insertSubview:loadingViewController.view atIndex:1000]; [UIView commitAnimations]; In the "loadingViewInserted" function, it calls another function doing the heavy computation work. Once the computation is done, a lot of result views (like checkers on a checker board) are rendered under the loading view. for(int colIndex = 1; colIndex <= result.columns; colIndex++) { for(int rowIndex = 1; rowIndex <= result.rows; rowIndex++) { ResultView *rv = [ResultView resultViewWithData:results[colIndex][rowIndex]]; [self.view addSubview:rv]; } } Once all result views are added, following animation is invoked to remove the loading view: [UIView beginAnimations:nil context:nil]; [UIView setAnimationDuration:1.0]; [UIView setAnimationBeginsFromCurrentState:YES]; [UIView setAnimationTransition:UIViewAnimationTransitionCurlUp forView:self.view cache:YES]; [loadingViewController.view removeFromSuperview]; [UIView commitAnimations]; By doing this, most of the time (maybe 90%) it does exactly what I want. However, sometime I see some weird result: the loading view shows up first as expected, then before it disappears, some result views, which suppose to be under the loading view, suddenly appears on top of the loading view; and some of them are partial rendered. And then the loading view curled up, and everything looks normal again. The weird situation only lasts for less than a second, but already bad enough to screw up the UI. I have tried all different kinds of thing to fix this (using another thread to remove the loading view, make the loading view non-transparent), but none of them works. The only thing that makes a little better is, I hide all the result views first; after the last animation finished, in its call back, unhide all result views. But this loses the nice effect that when curling up the loading view, the results are already there. At this point, I really think this is a bug in iphone (I compile it with OS 3.0) OS. Or maybe you can point out what I have done wrong (or could do differently). (thanks for finishing this long post, :-) )

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Subscribing message sent from another application

- by tonga

I have two Java applications: AppOne and AppTwo. In AppOne, I used a JMS sender to publish a Topic. In both AppOne and AppTwo, I used a JMS MessageListener to subscribe to the message published by AppOne. I used ActiveMQ as my JMS broker and Spring JMS. However, I can only see the echoed message received by AppOne message listener. But I can't see the echoed message received by AppTwo listener. AppOne message listener is in the same application/project as the message publisher. But AppTwo message listener is in a different application/project. The AppOne listener class is: public class CustomerStatusListener implements MessageListener { public void onMessage(Message message) { if (message instanceof TextMessage) { try { System.out.println("Subscriber 1 got you! The message is: " + ((TextMessage) message).getText()); } catch (JMSException ex) { throw new RuntimeException(ex); } } else { throw new IllegalArgumentException("Message must be of type TextMessage"); } } } It is invoked by a test calss JmsTest in AppOne: public class JmsTest { public static void main(String[] args) { ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("message-bean.xml"); CustomerStatusSender messageSender = (CustomerStatusSender) context.getBean("customerMessageSender"); messageSender.simpleSend(); context.close(); } } The AppTwo listener class is: public class CustomerStatusMessageListener implements MessageListener { public void onMessage(Message message) { if (message instanceof TextMessage) { try { System.out.println("Subscriber 2 got you! The message is: " + ((TextMessage) message).getText()); } catch (JMSException ex) { throw new RuntimeException(ex); } } else { throw new IllegalArgumentException( "Message must be of type TextMessage"); } } } The bean definition file for AppTwo where the Subscriber 2 lives in is: <bean id="connectionFactoryBean" class="org.apache.activemq.ActiveMQConnectionFactory"> <property name="brokerURL" value="tcp://localhost:61616" /> </bean>  <bean id="customerStatusListener" class="com.mydomain.jms.CustomerStatusMessageListener" />  <bean id="listenerContainer" class="org.springframework.jms.listener.DefaultMessageListenerContainer"> <property name="connectionFactory" ref="connectionFactoryBean" /> <property name="destination" ref="topicBean" /> <property name="messageListener" ref="customerStatusListener" /> </bean> The bean id topicBean is the bean that is associated with the publisher. If both listener received the message sent from AppOne, I would have seen two echoed messages: Subscriber 1 got you! The message is: hello world Subscriber 2 got you! The message is: hello world But right now I only see the first line which means only the listener in AppOne got the message. So how to let the listener in AppTwo get the message? The first listener is in the same application as the sender, so it is easy to understand that it can get the message. But how about the second listener which is in a different application? What is the correct way to subscribe to a JMS Topic published in another application?

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How to use XSLT to tag specific nodes with unique, sequential, increasing integer ids?

- by ~otakuj462

Hi, I'm trying to use XSLT to transform a document by tagging a group of XML nodes with integer ids, starting at 0, and increasing by one for each node in the group. The XML passed into the stylesheet should be echoed out, but augmented to include this extra information. Just to be clear about what I am talking about, here is how this transformation would be expressed using DOM: states = document.getElementsByTagName("state"); for( i = 0; i < states.length; i++){ states.stateNum = i; } This is very simple with DOM, but I'm having much more trouble doing this with XSLT. The current strategy I've devised has been to start with the identity transformation, then create a global variable which selects and stores all of the nodes that I wish to number. I then create a template that matches that kind of node. The idea, then, is that in the template, I would look up the matched node's position in the global variable nodelist, which would give me a unique number that I could then set as an attribute. The problem with this approach is that the position function can only be used with the context node, so something like the following is illegal: <template match="state"> <variable name="stateId" select="@id"/> <variable name="uniqueStateNum" select="$globalVariable[@id = $stateId]/position()"/> </template> The same is true for the following: <template match="state"> <variable name="stateId" select="@id" <variable name="stateNum" select="position($globalVariable[@id = $stateId])/"/> </template> In order to use position() to look up the position of an element in $globalVariable, the context node must be changed. I have found a solution, but it is highly suboptimal. Basically, in the template, I use for-each to iterate through the global variable. For-each changes the context node, so this allows me to use position() in the way I described. The problem is that this turns what would normally be an O(n) operation into an O(n^2) operation, where n is the length of the nodelist, as this require iterating through the whole list whenever the template is matched. I think that there must be a more elegant solution. Altogether, here is my current (slightly simplified) xslt stylesheet: <?xml version="1.0"?> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:s="http://www.w3.org/2005/07/scxml" xmlns="http://www.w3.org/2005/07/scxml" xmlns:c="http://msdl.cs.mcgill.ca/" version="1.0"> <xsl:output method="xml"/>  <xsl:variable name="states" select="//s:state" />  <xsl:template match="@*|node()"> <xsl:copy> <xsl:apply-templates select="@*|node()"/> </xsl:copy> </xsl:template> <xsl:template match="s:state"> <xsl:variable name="stateId"> <xsl:value-of select="@id"/> </xsl:variable> <xsl:copy> <xsl:apply-templates select="@*"/> <xsl:for-each select="$states"> <xsl:if test="@id = $stateId"> <xsl:attribute name="stateNum" namespace="http://msdl.cs.mcgill.ca/"> <xsl:value-of select="position()"/> </xsl:attribute> </xsl:if> </xsl:for-each> <xsl:apply-templates select="node()"/> </xsl:copy> </xsl:template> </xsl:stylesheet> I'd appreciate any advice anyone can offer. Thanks.

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TableView doesnt show any Data(CoreData) - App crashe

- by brush51

Hey @all, i cant read my data from my database. I have an app with a tabbarcontroller. in the first tab the iphone camera takes a picture from a barcode and send the result to another view (CameraReturnDetailViewController). In CameraReturnDetailViewController is the savebutton, and here is the code from this save button: - (IBAction)saveAndQuitScan:(id) sender { XLog(@"saveAndQuitScan button wurde geklickt!"); ProjectQRCodeAppDelegate *appDelegate = [[UIApplication sharedApplication]delegate]; NSManagedObjectContext *context = [appDelegate managedObjectContext]; NSManagedObject *newData; newData = [NSEntityDescription insertNewObjectForEntityForName:@"BarcodeDaten" inManagedObjectContext:context]; [newData setValue:dataLabel.text forKey:@"Barcode_CD"]; NSError *error; [context save:&error]; //Aktuelle ansicht (self) animiert verlassen [self dismissModalViewControllerAnimated:YES]; // Nachdem die ansicht verlassen wurde, // auf das zweite Tab wechseln(scanverlauf) /** TO DO - Funktioniert noch nicht **/ [self.tabBarController setSelectedIndex:1]; } Now, my aim is to show the taba in the second tab, in a TableView (ScansViewController): - (void)viewDidLoad { [super viewDidLoad]; if (managedObjectContext_ == nil) { managedObjectContext_ = [(ProjectQRCodeAppDelegate *)[[UIApplication sharedApplication]delegate] managedObjectContext]; NSLog(@"After managedObjectContext: %@", managedObjectContext_); } myTableView = [[UITableView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame] style:UITableViewStylePlain]; myTableView.delegate = self; myTableView.dataSource = self; myTableView.autoresizesSubviews = YES; self.navigationItem.title = @"Code Liste"; self.view = myTableView; } - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { return [itemsList count]; } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"Cell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:CellIdentifier] autorelease]; } return cell; } - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView { return 1; } - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { NSString *selectDay = [NSString stringWithFormat:@"%d", indexPath.row]; TableDetailViewController *fvController = [[TableDetailViewController alloc] initWithNibName:@"TableDetailViewController" bundle:[NSBundle mainBundle]]; fvController.selectDay = selectDay; [self.navigationController pushViewController:fvController animated:YES]; [fvController release]; fvController = nil; } - (void) configureCell:(UITableViewCell *)cell atIndexPath:(NSIndexPath *)indexPath { NSManagedObject *managedObject = [self.fetchedResultsController objectAtIndexPath:indexPath]; cell.textLabel.text = [[managedObject valueForKey:@"Barcode_CD"] description]; } - (NSFetchedResultsController *) fetchedResultsController { if (fetchedResultsController_ !=nil) { return fetchedResultsController_; } NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; NSEntityDescription *entity = [NSEntityDescription entityForName:@"BarcodeDaten" inManagedObjectContext:self.managedObjectContext]; [fetchRequest setEntity:entity]; [fetchRequest setFetchBatchSize:20]; NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"Barcode_CD" ascending:NO]; NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil]; [fetchRequest setSortDescriptors:sortDescriptors]; NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:self.managedObjectContext sectionNameKeyPath:nil cacheName:@"Root"]; aFetchedResultsController.delegate = self; self.fetchedResultsController = aFetchedResultsController; [aFetchedResultsController release]; [fetchRequest release]; [sortDescriptor release]; [sortDescriptors release]; NSError *error = nil; if (![fetchedResultsController_ performFetch:&error]) { XLog(@"Error: %@, %@", error, [error userInfo]); abort(); } return fetchedResultsController_; } At first i get this error when i choosed the second tab(ScansViewController): " Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: '+entityForName: could not locate an NSManagedObjectModel for entity name 'BarcodeDaten'' " The Name is correct but i dont understand my mistake. No data is showed in the Tableview, why? Have I missed something..? Or something wrong? Thanks for help, brush51

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Looking for suggestions on how to reuse AlertDialogs to confirm actions of contextual menus on the items of an ActivityList

- by Ozone

I use a ListActivity to display a list of items. The user can long-press an item in the list to display a contextual menu. This menu contains among other things an option to delete the long-pressed item. When the user selects this option, a dialog pops up asking for confirmation of the deletion. Upon confirmation, the item is deleted from the list. I would like to reuse the AlertDialog as much as possible. My attempts at using onPrepareDialog(int, View, Bundle) have been defeated by the fact that the Bundle is not passed to the DialogInterface.OnClickListener. I end up having to recreate a listener on every invocation. I see several ways to solve this: recreate the dialog on every occasion (pros: simple, cons: wasteful) keep the DialogInterface.OnClickListener in a field on the ListActivity and keep the item to be deleted as a field of the listener. (pros: no memory waste, cons: need to manage state). Q: is this safe? have onPrepareDialog update the title, and bind new View.OnClickListeners on the buttons of the AlertDialog. (pros: limit waste, cons: new View.OnClickListener on every invocation). If DialogInterface.OnClickListener accepted a Bundle, I wouldn't have to jump through hoops to keep track of the item being deleted. This is not a blocker, but I would love to see an elegant solution. I would love to hear your suggestions :) Here is the code for option #1, if you want to play with this: public class Example extends ListActivity { private static final int CONFIRM_DELETE_DIALOG = 1; private static final String POSITION_KEY = "position"; private ArrayAdapter<String> mAdapter; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); mAdapter = new ArrayAdapter<String>( this, android.R.layout.simple_list_item_1, new String[] { "one", "two" }); setListAdapter(mAdapter); registerForContextMenu(getListView()); } @Override public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) { super.onCreateContextMenu(menu, v, menuInfo); getMenuInflater().inflate(R.menu.my_lovely_menu, menu); } @Override public boolean onContextItemSelected(MenuItem item) { AdapterContextMenuInfo info = (AdapterContextMenuInfo) item.getMenuInfo(); switch (item.getItemId()) { case R.id.delete_item: Bundle bundle = new Bundle(); bundle.putInt(POSITION_KEY, info.position); showDialog(CONFIRM_DELETE_DIALOG, bundle); return true; default: return super.onContextItemSelected(item); } } @Override protected Dialog onCreateDialog(int id, Bundle args) { switch (id) { case CONFIRM_DELETE_DIALOG: final int position = args.getInt(POSITION_KEY); AlertDialog.Builder builder = new AlertDialog.Builder(); builder.setCancelable(false); builder.setTitle(String.format( getString(R.string.confirm_delete), mAdapter.getItem(position))); DialogInterface.OnClickListener listener = new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int which) { switch (which) { case DialogInterface.BUTTON_POSITIVE: mAdapter.remove(mAdapter.getItem(position)); // Dismiss the dialog to ensure OnDismissListeners are notified. dialog.dismiss(); break; case DialogInterface.BUTTON_NEGATIVE: // Cancel the dialog to ensure OnCancelListeners are notified. dialog.cancel(); break; } // Remove the dialog so it is re-created next time it is required. removeDialog(CONFIRM_DELETE_DIALOG); } }; builder.setPositiveButton(android.R.string.yes, listener); builder.setNegativeButton(android.R.string.no, listener); return builder.create(); default: return super.onCreateDialog(id, args); } } }

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How to debug KVO

- by user8472

In my program I use KVO manually to observe changes to values of object properties. I receive an EXC_BAD_ACCESS signal at the following line of code inside a custom setter: [self willChangeValueForKey:@"mykey"]; The weird thing is that this happens when a factory method calls the custom setter and there should not be any observers around. I do not know how to debug this situation. Update: The way to list all registered observers is observationInfo. It turned out that there was indeed an object listed that points to an invalid address. However, I have no idea at all how it got there. Update 2: Apparently, the same object and method callback can be registered several times for a given object - resulting in identical entries in the observed object's observationInfo. When removing the registration only one of these entries is removed. This behavior is a little counter-intuitive (and it certainly is a bug in my program to add multiple entries at all), but this does not explain how spurious observers can mysteriously show up in freshly allocated objects (unless there is some caching/reuse going on that I am unaware of). Modified question: How can I figure out WHERE and WHEN an object got registered as an observer? Update 3: Specific sample code. ContentObj is a class that has a dictionary as a property named mykey. It overrides: + (BOOL)automaticallyNotifiesObserversForKey:(NSString *)theKey { BOOL automatic = NO; if ([theKey isEqualToString:@"mykey"]) { automatic = NO; } else { automatic=[super automaticallyNotifiesObserversForKey:theKey]; } return automatic; } A couple of properties have getters and setters as follows: - (CGFloat)value { return [[[self mykey] objectForKey:@"value"] floatValue]; } - (void)setValue:(CGFloat)aValue { [self willChangeValueForKey:@"mykey"]; [[self mykey] setObject:[NSNumber numberWithFloat:aValue] forKey:@"value"]; [self didChangeValueForKey:@"mykey"]; } The container class has a property contents of class NSMutableArray which holds instances of class ContentObj. It has a couple of methods that manually handle registrations: + (BOOL)automaticallyNotifiesObserversForKey:(NSString *)theKey { BOOL automatic = NO; if ([theKey isEqualToString:@"contents"]) { automatic = NO; } else { automatic=[super automaticallyNotifiesObserversForKey:theKey]; } return automatic; } - (void)observeContent:(ContentObj *)cObj { [cObj addObserver:self forKeyPath:@"mykey" options:0 context:NULL]; } - (void)removeObserveContent:(ContentObj *)cObj { [cObj removeObserver:self forKeyPath:@"mykey"]; } - (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context { if (([keyPath isEqualToString:@"mykey"]) && ([object isKindOfClass:[ContentObj class]])) { [self willChangeValueForKey:@"contents"]; [self didChangeValueForKey:@"contents"]; } } There are several methods in the container class that modify contents. They look as follows: - (void)addContent:(ContentObj *)cObj { [self willChangeValueForKey:@"contents"]; [self observeDatum:cObj]; [[self contents] addObject:cObj]; [self didChangeValueForKey:@"contents"]; } And a couple of others that provide similar functionality to the array. They all work by adding/removing themselves as observers. Obviously, anything that results in multiple registrations is a bug and could sit somewhere hidden in these methods. My question targets strategies on how to debug this kind of situation. Alternatively, please feel free to provide an alternative strategy for implementing this kind of notification/observer pattern.

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iphone keyboard won't appear

- by d_CFO

I can click on the field, and it momentarily turns blue, but those events plus makeFirstResponder together do not cause the keyboard to show on a UITextField. Plain vanilla code follows; I include it so others can discern what is NOT there and therefore what, presumably, with solve the problem. I put in leading spaces to format this question more like code, but the parser seems to have stripped them, thus leaving left-justified code. Sorry! UITextFieldDelete, check: @interface RevenueViewController : UIViewController <UITableViewDelegate, UITableViewDataSource, UITextFieldDelegate> { UILabel *sgmntdControlLabel; UISegmentedControl *sgmntdControl; UITableView *theTableView; } @property(nonatomic,retain) UISegmentedControl *sgmntdControl; @property(nonatomic,retain) UILabel *sgmntdControlLabel; Delegate and source, check. -(void)loadView; // code CGRect frameTable = CGRectMake(10,0,300,260); theTableView = [[UITableView alloc] initWithFrame:frameTable style:UITableViewStyleGrouped]; [theTableView setDelegate:self]; [theTableView setDataSource:self]; // code [self.view addSubview:theTableView]; [super viewDidLoad]; } Insert UITextField to cell, check. - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { NSInteger sectionNmbr = [indexPath section]; NSInteger rowNmbr = [indexPath row]; NSLog(@"cellForRowAtIndexPath=%d, %d",sectionNmbr,rowNmbr); static NSString *CellIdentifier = @"Cell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease]; } // Configure the cell. switch (sectionNmbr) { case 0: if (rowNmbr == 0) { cell.tag = 1; cell.textLabel.text = @"Label for sctn 0, row 0"; UITextField *tf = [[UITextField alloc] init]; tf.keyboardType = UIKeyboardTypeNumberPad; tf.returnKeyType = UIReturnKeyDone; tf.delegate = self; [cell.contentView addSubview:tf]; } if (rowNmbr == 1) { cell.tag = 2; cell.textLabel.text = @"Label for sctn 0, row 1"; cell.accessoryType = UITableViewCellAccessoryDetailDisclosureButton; } break; } } Successfully end up where we want to be (?), no check, (and no keyboard!): - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { NSLog(@"didSelectRowAtIndexPath"); switch (indexPath.section) { case 0: NSLog(@" section=0, rowNmbr=%d",indexPath.row); switch (indexPath.row) { case 0: UITableViewCell *cellSelected = [tableView cellForRowAtIndexPath: indexPath]; UITextField *textField = [[cellSelected.contentView subviews] objectAtIndex: 0]; [ textField setEnabled: YES ]; [textField becomeFirstResponder]; // here is where keyboard will appear? [tableView deselectRowAtIndexPath: indexPath animated: NO]; break; case 1: // code break; default: break; } break; case 1: // code break; default: // handle otherwise un-handled exception break; } } Thank you for your insights!

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Android how to match text with images by pointing text and images with lines

- by Shirisha

I am trying to create app which is match text with appropriate images by pointing with line. I want to create app exactly same which is shown in the below image: can any one please give me an idea? This is my main class: public class MatchActivity extends Activity { ArrayAdapter<String> listadapter; float x1; float y1; float x2; float y2; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); String[] s1 = { "smiley1", "smiley2", "smiley3" }; ListView lv = (ListView) findViewById(R.id.text_list); ArrayList<String> list = new ArrayList<String>(); list.addAll(Arrays.asList(s1)); listadapter = new ArrayAdapter<String>(this, R.layout.rowtext, s1); lv.setAdapter(listadapter); GridView gv = (GridView) findViewById(R.id.image_list); gv.setAdapter(new ImageAdapter(this)); lv.setOnItemClickListener(new OnItemClickListener() { public void onItemClick(AdapterView<?> arg0, View v, int arg2, long arg3){ x1=v.getX(); y1=v.getY(); Log.d("list","text positions x1:"+x1+" y1:"+y1); } }); gv.setOnItemClickListener(new OnItemClickListener() { public void onItemClick(AdapterView<?> arg0, View v, int arg2, long arg3){ DrawView draw=new DrawView(MatchActivity.this); x2=v.getX(); y2=v.getY(); draw.position1.add(x1); draw.position1.add(y1); draw.position2.add( x2); draw.position2.add(y2); Log.d("list","image positions x2:"+x2+" y2:"+y2); LinearLayout ll=LinearLayout)findViewById(R.id.draw_line); ll.addView(draw); } }); } } This is my drawing class to draw a line: public class DrawView extends View { Paint paint = new Paint(); private List<Float> position1=new ArrayList<Float>(); private List<Float> position2=new ArrayList<Float>();; public DrawView(Context context) { super(context); invalidate(); Log.d("drawview","In DrawView class position1:"+position1+" position2:"+position2) ; } @Override public void onDraw(Canvas canvas) { super.onDraw(canvas); Log.d("on draw","IN onDraw() position1:"+position1+" position2:"+position2); assert position1.size() == position2.size(); for (int i = 0; i < position1.size(); i += 2) { float x1 = position1.get(i); float y1 = position1.get(i + 1); float x2 = position2.get(i); float y2 = position2.get(i + 1); paint.setColor(Color.BLACK); paint.setStrokeWidth(3); canvas.drawLine(x1,y1, x2,y2, paint); } } } Thanks in advance .

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Integrating WIF with WCF Data Services

- by cibrax

A time ago I discussed how a custom REST Starter kit interceptor could be used to parse a SAML token in the Http Authorization header and wrap that into a ClaimsPrincipal that the WCF services could use. The thing is that code was initially created for Geneva framework, so it got deprecated quickly. I recently needed that piece of code for one of projects where I am currently working on so I decided to update it for WIF. As this interceptor can be injected in any host for WCF REST services, also represents an excellent solution for integrating claim-based security into WCF Data Services (previously known as ADO.NET Data Services). The interceptor basically expects a SAML token in the Authorization header. If a token is found, it is parsed and a new ClaimsPrincipal is initialized and injected in the WCF authorization context. public class SamlAuthenticationInterceptor : RequestInterceptor { SecurityTokenHandlerCollection handlers; public SamlAuthenticationInterceptor() : base(false) { this.handlers = FederatedAuthentication.ServiceConfiguration.SecurityTokenHandlers; } public override void ProcessRequest(ref RequestContext requestContext) { SecurityToken token = ExtractCredentials(requestContext.RequestMessage); if (token != null) { ClaimsIdentityCollection claims = handlers.ValidateToken(token); var principal = new ClaimsPrincipal(claims); InitializeSecurityContext(requestContext.RequestMessage, principal); } else { DenyAccess(ref requestContext); } } private void DenyAccess(ref RequestContext requestContext) { Message reply = Message.CreateMessage(MessageVersion.None, null); HttpResponseMessageProperty responseProperty = new HttpResponseMessageProperty() { StatusCode = HttpStatusCode.Unauthorized }; responseProperty.Headers.Add("WWW-Authenticate", String.Format("Basic realm=\"{0}\"", "")); reply.Properties[HttpResponseMessageProperty.Name] = responseProperty; requestContext.Reply(reply); requestContext = null; } private SecurityToken ExtractCredentials(Message requestMessage) { HttpRequestMessageProperty request = (HttpRequestMessageProperty) requestMessage.Properties[HttpRequestMessageProperty.Name]; string authHeader = request.Headers["Authorization"]; if (authHeader != null && authHeader.Contains("<saml")) { XmlTextReader xmlReader = new XmlTextReader(new StringReader(authHeader)); var col = SecurityTokenHandlerCollection.CreateDefaultSecurityTokenHandlerCollection(); SecurityToken token = col.ReadToken(xmlReader); return token; } return null; } private void InitializeSecurityContext(Message request, IPrincipal principal) { List<IAuthorizationPolicy> policies = new List<IAuthorizationPolicy>(); policies.Add(new PrincipalAuthorizationPolicy(principal)); ServiceSecurityContext securityContext = new ServiceSecurityContext(policies.AsReadOnly()); if (request.Properties.Security != null) { request.Properties.Security.ServiceSecurityContext = securityContext; } else { request.Properties.Security = new SecurityMessageProperty() { ServiceSecurityContext = securityContext }; } } class PrincipalAuthorizationPolicy : IAuthorizationPolicy { string id = Guid.NewGuid().ToString(); IPrincipal user; public PrincipalAuthorizationPolicy(IPrincipal user) { this.user = user; } public ClaimSet Issuer { get { return ClaimSet.System; } } public string Id { get { return this.id; } } public bool Evaluate(EvaluationContext evaluationContext, ref object state) { evaluationContext.AddClaimSet(this, new DefaultClaimSet(System.IdentityModel.Claims.Claim.CreateNameClaim(user.Identity.Name))); evaluationContext.Properties["Identities"] = new List<IIdentity>(new IIdentity[] { user.Identity }); evaluationContext.Properties["Principal"] = user; return true; } } A WCF Data Service, as any other WCF Service, contains a service host where this interceptor can be injected. The following code illustrates how that can be done in the “svc” file. <%@ ServiceHost Language="C#" Debug="true" Service="ContactsDataService" Factory="AppServiceHostFactory" %> using System; using System.ServiceModel; using System.ServiceModel.Activation; using Microsoft.ServiceModel.Web; class AppServiceHostFactory : ServiceHostFactory { protected override ServiceHost CreateServiceHost(Type serviceType, Uri[] baseAddresses) { WebServiceHost2 result = new WebServiceHost2(serviceType, true, baseAddresses); result.Interceptors.Add(new SamlAuthenticationInterceptor()); return result; } } WCF Data Services includes an specific WCF host of out the box (DataServiceHost). However, the service is not affected at all if you replace it with a custom one as I am doing in the code above (WebServiceHost2 is part of the REST Starter kit). Finally, the client application needs to pass the SAML token somehow to the data service. In case you are using any Http client library for consuming the data service, that’s easy to do, you only need to include the SAML token as part of the “Authorization” header. If you are using the auto-generated data service proxy, a little piece of code is needed to inject a SAML token into the DataServiceContext instance. That class provides an event “SendingRequest” that any client application can leverage to include custom code that modified the Http request before it is sent to the service. So, you can easily create an extension method for the DataServiceContext that negotiates the SAML token with an existing STS, and adds that token as part of the “Authorization” header. public static class DataServiceContextExtensions { public static void ConfigureFederatedCredentials(this DataServiceContext context, string baseStsAddress, string realm) { string address = string.Format(STSAddressFormat, baseStsAddress, realm); string token = NegotiateSecurityToken(address); context.SendingRequest += (source, args) => { args.RequestHeaders.Add("Authorization", token); }; } private string NegotiateSecurityToken(string address) { } } I left the NegociateSecurityToken method empty for this extension as it depends pretty much on how you are negotiating tokens from an existing STS. In case you want to end-to-end REST solution that involves an Http endpoint for the STS, you should definitely take a look at the Thinktecture starter STS project in codeplex.

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SignalR Auto Disconnect when Page Changed in AngularJS

- by Shaun

Originally posted on: http://geekswithblogs.net/shaunxu/archive/2014/05/30/signalr-auto-disconnect-when-page-changed-in-angularjs.aspxIf we are using SignalR, the connection lifecycle was handled by itself very well. For example when we connect to SignalR service from browser through SignalR JavaScript Client the connection will be established. And if we refresh the page, close the tab or browser, or navigate to another URL then the connection will be closed automatically. This information had been well documented here. In a browser, SignalR client code that maintains a SignalR connection runs in the JavaScript context of a web page. That's why the SignalR connection has to end when you navigate from one page to another, and that's why you have multiple connections with multiple connection IDs if you connect from multiple browser windows or tabs. When the user closes a browser window or tab, or navigates to a new page or refreshes the page, the SignalR connection immediately ends because SignalR client code handles that browser event for you and calls the "Stop" method. But unfortunately this behavior doesn't work if we are using SignalR with AngularJS. AngularJS is a single page application (SPA) framework created by Google. It hijacks browser's address change event, based on the route table user defined, launch proper view and controller. Hence in AngularJS we address was changed but the web page still there. All changes of the page content are triggered by Ajax. So there's no page unload and load events. This is the reason why SignalR cannot handle disconnect correctly when works with AngularJS. If we dig into the source code of SignalR JavaScript Client source code we will find something below. It monitors the browser page "unload" and "beforeunload" event and send the "stop" message to server to terminate connection. But in AngularJS page change events were hijacked, so SignalR will not receive them and will not stop the connection. 1: // wire the stop handler for when the user leaves the page 2: _pageWindow.bind("unload", function () { 3: connection.log("Window unloading, stopping the connection."); 4: 5: connection.stop(asyncAbort); 6: }); 7: 8: if (isFirefox11OrGreater) { 9: // Firefox does not fire cross-domain XHRs in the normal unload handler on tab close. 10: // #2400 11: _pageWindow.bind("beforeunload", function () { 12: // If connection.stop() runs runs in beforeunload and fails, it will also fail 13: // in unload unless connection.stop() runs after a timeout. 14: window.setTimeout(function () { 15: connection.stop(asyncAbort); 16: }, 0); 17: }); 18: } Problem Reproduce In the codes below I created a very simple example to demonstrate this issue. Here is the SignalR server side code. 1: public class GreetingHub : Hub 2: { 3: public override Task OnConnected() 4: { 5: Debug.WriteLine(string.Format("Connected: {0}", Context.ConnectionId)); 6: return base.OnConnected(); 7: } 8: 9: public override Task OnDisconnected() 10: { 11: Debug.WriteLine(string.Format("Disconnected: {0}", Context.ConnectionId)); 12: return base.OnDisconnected(); 13: } 14: 15: public void Hello(string user) 16: { 17: Clients.All.hello(string.Format("Hello, {0}!", user)); 18: } 19: } Below is the configuration code which hosts SignalR hub in an ASP.NET WebAPI project with IIS Express. 1: public class Startup 2: { 3: public void Configuration(IAppBuilder app) 4: { 5: app.Map("/signalr", map => 6: { 7: map.UseCors(CorsOptions.AllowAll); 8: map.RunSignalR(new HubConfiguration() 9: { 10: EnableJavaScriptProxies = false 11: }); 12: }); 13: } 14: } Since we will host AngularJS application in Node.js in another process and port, the SignalR connection will be cross domain. So I need to enable CORS above. In client side I have a Node.js file to host AngularJS application as a web server. You can use any web server you like such as IIS, Apache, etc.. Below is the "index.html" page which contains a navigation bar so that I can change the page/state. As you can see I added jQuery, AngularJS, SignalR JavaScript Client Library as well as my AngularJS entry source file "app.js". 1: <html data-ng-app="demo"> 2: <head> 3: <script type="text/javascript" src="jquery-2.1.0.js"></script> 1: 2: <script type="text/javascript" src="angular.js"> 1: </script> 2: <script type="text/javascript" src="angular-ui-router.js"> 1: </script> 2: <script type="text/javascript" src="jquery.signalR-2.0.3.js"> 1: </script> 2: <script type="text/javascript" src="app.js"></script> 4: </head> 5: <body> 6: <h1>SignalR Auto Disconnect with AngularJS by Shaun</h1> 7: <div> 8: <a href="javascript:void(0)" data-ui-sref="view1">View 1</a> | 9: <a href="javascript:void(0)" data-ui-sref="view2">View 2</a> 10: </div> 11: <div data-ui-view></div> 12: </body> 13: </html> Below is the "app.js". My SignalR logic was in the "View1" page and it will connect to server once the controller was executed. User can specify a user name and send to server, all clients that located in this page will receive the server side greeting message through SignalR. 1: 'use strict'; 2: 3: var app = angular.module('demo', ['ui.router']); 4: 5: app.config(['$stateProvider', '$locationProvider', function ($stateProvider, $locationProvider) { 6: $stateProvider.state('view1', { 7: url: '/view1', 8: templateUrl: 'view1.html', 9: controller: 'View1Ctrl' }); 10: 11: $stateProvider.state('view2', { 12: url: '/view2', 13: templateUrl: 'view2.html', 14: controller: 'View2Ctrl' }); 15: 16: $locationProvider.html5Mode(true); 17: }]); 18: 19: app.value('$', $); 20: app.value('endpoint', 'http://localhost:60448'); 21: app.value('hub', 'GreetingHub'); 22: 23: app.controller('View1Ctrl', function ($scope, $, endpoint, hub) { 24: $scope.user = ''; 25: $scope.response = ''; 26: 27: $scope.greeting = function () { 28: proxy.invoke('Hello', $scope.user) 29: .done(function () {}) 30: .fail(function (error) { 31: console.log(error); 32: }); 33: }; 34: 35: var connection = $.hubConnection(endpoint); 36: var proxy = connection.createHubProxy(hub); 37: proxy.on('hello', function (response) { 38: $scope.$apply(function () { 39: $scope.response = response; 40: }); 41: }); 42: connection.start() 43: .done(function () { 44: console.log('signlar connection established'); 45: }) 46: .fail(function (error) { 47: console.log(error); 48: }); 49: }); 50: 51: app.controller('View2Ctrl', function ($scope, $) { 52: }); When we went to View1 the server side "OnConnect" method will be invoked as below. And in any page we send the message to server, all clients will got the response. If we close one of the client, the server side "OnDisconnect" method will be invoked which is correct. But is we click "View 2" link in the page "OnDisconnect" method will not be invoked even though the content and browser address had been changed. This might cause many SignalR connections remain between the client and server. Below is what happened after I clicked "View 1" and "View 2" links four times. As you can see there are 4 live connections. Solution Since the reason of this issue is because, AngularJS hijacks the page event that SignalR need to stop the connection, we can handle AngularJS route or state change event and stop SignalR connect manually. In the code below I moved the "connection" variant to global scope, added a handler to "$stateChangeStart" and invoked "stop" method of "connection" if its state was not "disconnected". 1: var connection; 2: app.run(['$rootScope', function ($rootScope) { 3: $rootScope.$on('$stateChangeStart', function () { 4: if (connection && connection.state && connection.state !== 4 /* disconnected */) { 5: console.log('signlar connection abort'); 6: connection.stop(); 7: } 8: }); 9: }]); Now if we refresh the page and navigated to View 1, the connection will be opened. At this state if we clicked "View 2" link the content will be changed and the SignalR connection will be closed automatically. Summary In this post I demonstrated an issue when we are using SignalR with AngularJS. The connection cannot be closed automatically when we navigate to other page/state in AngularJS. And the solution I mentioned below is to move the SignalR connection as a global variant and close it manually when AngularJS route/state changed. You can download the full sample code here. Moving the SignalR connection as a global variant might not be a best solution. It's just for easy to demo here. In production code I suggest wrapping all SignalR operations into an AngularJS factory. Since AngularJS factory is a singleton object, we can safely put the connection variant in the factory function scope. Hope this helps, Shaun All documents and related graphics, codes are provided "AS IS" without warranty of any kind. Copyright © Shaun Ziyan Xu. This work is licensed under the Creative Commons License.

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Entity Framework v1 … Brief Synopsis and Tips – Part 2

- by Rohit Gupta

Using Entity Framework with ASMX Web sErvices and WCF Web Service: If you use ASMX WebService to expose Entity objects from Entity Framework... then the ASMX Webservice does not include object graphs, one work around is to use Facade pattern or to use WCF Service. The other important aspect of using ASMX Web Services along with Entity Framework is that the ASMX Client is not aware of the existence of EF v1 since the client solely deals with C# objects (not EntityObjects or ObjectContext). Since the client is not aware of the ObjectContext hence the client cannot participate in change tracking since the client only receives the Current Values and not the Orginal values when the service sends the the Entity objects to the client. Thus there are 2 drawbacks to using EntityFramework with ASMX Web Service: 1. Object state is not maintained... so to overcome this limitation we need insert/update single entity at a time and retrieve the original values for the entity being updated on the server/service end before calling Save Changes. 2. ASMX does not maintain object graphs... i.e. Customer.Reservations or Customer.Reservations.Trip relationships are not maintained. Thus you need to send these relationships separately from service to client. WCF Web Service overcomes the object graph limitation of ASMX Web Service, but we need to insure that we are populating all the non-null scalar properties of all the objects in the object graph before calling Update. WCF Web service still cannot overcome the second limitation of tracking changes to entities at the client end. Also note that the "Customer" class in the Client is very different from the "Customer" class in the Entity Framework Model Entities. They are incompatible with each other hence we cannot cast one to the other. However the .NET Framework translates the client "Customer" Entity to the EFv1 Model "customer" Entity once the entity is serialzed back on the ASMX server end. If you need change tracking enabled on the client then we need to use WCF Data Services which is available with VS 2010. ====================================================================================================== In WCF when adding an object that has relationships, the framework assumes that every object in the object graph needs to be added to store. for e.g. in a Customer.Reservations.Trip object graph, when a Customer Entity is added to the store, the EFv1 assumes that it needs to a add a Reservations collection and also Trips for each Reservation. Thus if we need to use existing Trips for reservations then we need to insure that we null out the Trip object reference from Reservations and set the TripReference to the EntityKey of the desired Trip instead. ====================================================================================================== Understanding Relationships and Associations in EFv1 The Golden Rule of EF is that it does not load entities/relationships unless you ask it to explicitly do so. However there is 1 exception to this rule. This exception happens when you attach/detach entities from the ObjectContext. If you detach an Entity in a ObjectGraph from the ObjectContext, then the ObjectContext removes the ObjectStateEntry for this Entity and all the relationship Objects associated with this Entity. For e.g. in a Customer.Order.OrderDetails if the Customer Entity is detached from the ObjectContext then you cannot traverse to the Order and OrderDetails Entities (that still exist in the ObjectContext) from the Customer Entity(which does not exist in the Object Context) Conversely, if you JOIN a entity that is not in the ObjectContext with a Entity that is in the ObjContext then the First Entity will automatically be added to the ObjContext since relationships for the 2 Entities need to exist in the ObjContext. ========================================================= You cannot attach an EntityCollection to an entity through its navigation property for e.g. you cannot code myContact.Addresses = myAddressEntityCollection ========================================================== Cascade Deletes in EDM: The Designer does not support specifying cascase deletes for a Entity. To enable cascasde deletes on a Entity in EDM use the Association definition in CSDL for the Entity. for e.g. SalesOrderDetail (SOD) has a Foreign Key relationship with SalesOrderHeader (SalesOrderHeader 1 : SalesOrderDetail *) if you specify a cascade Delete on SalesOrderHeader Entity then calling deleteObject on SalesOrderHeader (SOH) Entity will send delete commands for SOH record and all the SOD records that reference the SOH record. ========================================================== As a good design practise, if you use Cascade Deletes insure that Cascade delete facet is used both in the EDM as well as in the database. Even though it is not absolutely mandatory to have Cascade deletes on both Database and EDM (since you can see that just the Cascade delete spec on the SOH Entity in EDM will insure that SOH record and all related SOD records will be deleted from the database ... even though you dont have cascade delete configured in the database in the SOD table) ============================================================== Maintaining relationships in Code When Setting a Navigation property of a Entity (for e.g. setting the Contact Navigation property of Address Entity) the following rules apply : If both objects are detached, no relationship object will be created. You are simply setting a property the CLR way. If both objects are attached, a relationship object will be created. If only one of the objects is attached, the other will become attached and a relationship object will be created. If that detached object is new, when it is attached to the context its EntityState will be Added. One important rule to remember regarding synchronizing the EntityReference.Value and EntityReference.EntityKey properties is that when attaching an Entity which has a EntityReference (e.g. Address Entity with ContactReference) the Value property will take precedence and if the Value and EntityKey are out of sync, the EntityKey will be updated to match the Value. ====================================================== If you call .Load() method on a detached Entity then the .Load() operation will throw an exception. There is one exception to this rule. If you load entities using MergeOption.NoTracking, you will be able to call .Load() on such entities since these Entities are accessible by the ObjectContext. So the bottomline is that we need Objectontext to be able to call .Load() method to do deffered loading on EntityReference or EntityCollection. Another rule to remember is that you cannot call .Load() on entities that have a EntityState.Added State since the ObjectContext uses the EntityKey of the Primary (Parent) Entity when loading the related (Child) Entity (and not the EntityKey of the child (even if the EntityKey of the child is present before calling .Load()) ====================================================== You can use ObjContext.Add() to add a entity to the ObjContext and set the EntityState of the new Entity to EntityState.Added. here no relationships are added/updated. You can also use EntityCollection.Add() method to add an entity to another entity's related EntityCollection for e.g. contact has a Addresses EntityCollection so to add a new address use contact.Addresses.Add(newAddress) to add a new address to the Addresses EntityCollection. Note that if the entity does not already exist in the ObjectContext then calling contact.Addresses.Add(myAddress) will cause a new Address Entity to be added to the ObjContext with EntityState.Added and it will also add a RelationshipEntry (a relationship object) with EntityState.Added which connects the Contact (contact) with the new address newAddress. Note that if the entity already exists in the Objectcontext (being part theOtherContact.Addresses Collection), then calling contact.Addresses.Add(existingAddress) will add 2 RelationshipEntry objects to the ObjectStateEntry Collection, one with EntityState.Deleted and the other with EntityState.Added. This implies that the existingAddress Entity is removed from the theOtherContact.Addresses Collection and Added to the contact.Addresses Collection..effectively reassigning the address entity from the theOtherContact to "contact". This is called moving an existing entity to a new object graph. ====================================================== You usually use ObjectContext.Attach() and EntityCollection.Attach() methods usually when you need to reconstruct the ObjectGraph after deserializing the objects as received from a ASMX Web Service Client. Attach is usually used to connect existing Entities in the ObjectContext. When EntityCollection.Attach() is called the EntityState of the RelationshipEntry (the relationship object) remains as EntityState.unchanged whereas when EntityCollection.Add() method is called the EntityState of the relationship object changes to EntityState.Added or EntityState.Deleted as the situation demands. ========================================================= LINQ To Entities Tips: Select Many does Inner Join by default. for e.g. from c in Contact from a in c.Address select c ... this will do a Inner Join between the Contacts and Addresses Table and return only those Contacts that have a Address. ======================================================== Group Joins Do LEFT Join by default. e.g. from a in Address join c in Contact ON a.Contact.ContactID == c.ContactID Into g WHERE a.CountryRegion == "US" select g; This query will do a left join on the Contact table and return contacts that have a address in "US" region The following query : from c in Contact join a in Address.Where(a1 => a1.CountryRegion == "US") on c.ContactID equals a.Contact.ContactID into addresses select new {c, addresses} will do a left join on the Address table and return All Contacts. In these Contacts only those will have its Address EntityCollection Populated which have a Address in the "US" region, the other contacts will have 0 Addresses in the Address collection (even if addresses for those contacts exist in the database but are in a different region) ======================================================== Linq to Entities does not support DefaultIfEmpty().... instead use .Include("Address") Query Builder method to do a Left JOIN or use Group Joins if you need more control like Filtering on the Address EntityCollection of Contact Entity =================================================================== Use CreateSourceQuery() on the EntityReference or EntityCollection if you need to add filters during deferred loading of Entities (Deferred loading in EFv1 happens when you call Load() method on the EntityReference or EntityCollection. for e.g. var cust=context.Contacts.OfType<Customer>().First(); var sq = cust.Reservations.CreateSourceQuery().Where(r => r.ReservationDate > new DateTime(2008,1,1)); cust.Reservations.Attach(sq); This populates only those reservations that are older than Jan 1 2008. This is the only way (in EFv1) to Attach a Range of Entities to a EntityCollection using the Attach() method ================================================================== If you need to get the Foreign Key value for a entity e.g. to get the ContactID value from a Address Entity use this : address.ContactReference.EntityKey.EntityKeyValues.Where(k=> k.Key == "ContactID")

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CodePlex Daily Summary for Thursday, April 29, 2010

CodePlex Daily Summary for Thursday, April 29, 2010New ProjectsDesign Technology Laboratory: DTL project is prominent.Em-Lib: Electronic Music Library เป็นโปรแกรมที่พัฒนาขึ้นเพื่อให้เป็นห้องสมุดอิเล็กทรอนิกส์ โดยตัวโปรแกรมจะสามารถจำลองเครื่องดนตรี พร้อมข้อมูลที่เกี่ย...Extensions For ASP.NET: Extensions For ASP.NETFIM 2010 PowerShell Cmdlets: These PowerShell cmdlets let you manage objects in the Forefront Identity Manager 2010 web service easily and concisely. The five cmdlets let you e...Grunty OS: Grunty OS is a Free open source OS made my GruntXproductionsIrishDevelopers.net Test: IrishDevelopers.net TestJobping Url Shortener: MVC 2 project that Shortens urls Fully functioning 'bare bones' url shortening website. Just 1 page to create and display the short url. 'API' ...Made In Hell: Small console game. Just a training in code writings.manx: manx is a system for managing catalogs of technical documents. 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Minor changes for rest.Event Scavenger: Version 3.2.2: Added setting to enable/disable creation of historic data.FIM 2010 PowerShell Cmdlets: Initial Release of FIM 2010 PowerShell Cmdlets: Initial release of FIM 2010 PowerShell cmdlets based on open source FIM web service client. Install by running installutil on Quest.FIMPowerhellSna...Fix.ly: Fix.ly 0.2: Fixed a bug where non-verbose mode would not workJobping Url Shortener: Deployment Code v0.1: Contains only the files necessary to run the Url Shortener website. Just provide a valid connection string in the web.configMetabolite Enterprise Libraries for EPiServer CMS using Page Type Builder: Metabolite Enterprise Libraries 1.1: This is the release of the Metabolite Enterprise Libraries 1.1 for use with EPiServer 5 R2 SP2 and Page Type Builder 1.1. 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Major Changes (1.5 -> 2.0 release candid...NodeXL: Network Overview, Discovery and Exploration for Excel: NodeXL Excel 2007 Template, version 1.0.1.122: The NodeXL Excel 2007 template displays a network graph using edge and vertex lists stored in an Excel 2007 workbook. What's NewThis version signi...nRoute Framework: nRoute.Toolkit Release Version 0.4.5: Release Targets, Silverlight and WPF: - Targets Silverlight 4 for Web - Targets WPF in .NET 4 for Desktop nRoute Dependencies: - System.Windows...NSIS Autorun: NSIS Autorun 0.1.4: NSIS Autorun 0.1.4 This release includes source code, application binary, and example materials.OpenNETCF.WindowsMobile.Ink: Initial Release: This is the source as originally hosted in the OpenNETCF SVN server.Resharper Settings Manager: RSM v2.1: Warning! The 'Load Settings File...' menu item won't show up in VS 2008. Will release an update soon. ChangesReworked plug-in options UI: Split RSM...RoTwee: RoTwee (11.1.0.0): Rotation is improved from 11.0.0.3.SharePoint 2010 Bulk Document Importer: SharePoint 2010 Bulk Document Importer 1.0.0.0: Features in 1.0.0.0 Command line interface Import folders and files with all subfolders Can be run from outside the SharePoint Server. Every a...sMAPedit: sMAPedit v0.6 (Base): + base version containing the applicaion & html resourcesSocialCare: SocialCare_src: Codigo Fonte da Aplicação e Banco de DadosTFS Code Comment Checking Policy (CCCP): CCCP 4.0 for VS2010: This release installs side-by-side with CCCP 3.0 for VS2008 SP1.VCC: Latest build, v2.1.30428.0: Automatic drop of latest buildVCC: Latest build, v2.1.30428.1: Automatic drop of latest buildVCC: Latest build, v2.1.30428.2: Automatic drop of latest buildХрень для ао: Первый релиз: Пробую что это такое.Most Popular ProjectsRawrWBFS ManagerAJAX Control Toolkitpatterns & practices – Enterprise LibrarySilverlight ToolkitMicrosoft SQL Server Product Samples: DatabaseWindows Presentation Foundation (WPF)ASP.NETiTuner - The iTunes CompanionMicrosoft SQL Server Community & SamplesMost Active Projectspatterns & practices – Enterprise LibraryRawrHydroServer - CUAHSI Hydrologic Information System ServerIonics Isapi Rewrite FilterGMap.NET - Great Maps for Windows Forms & PresentationNB_Store - Free DotNetNuke Ecommerce Catalog ModuleParticle Plot PivotSqlDiffFramework-A Visual Differencing Engine for Dissimilar Data SourcesN2 CMSBlogEngine.NET

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Clustering Basics and Challenges

- by Karoly Vegh

For upcoming posts it seemed to be a good idea to dedicate some time for cluster basic concepts and theory. This post misses a lot of details that would explode the articlesize, should you have questions, do not hesitate to ask them in the comments. The goal here is to get some concepts straight. I can't promise to give you an overall complete definitions of cluster, cluster agent, quorum, voting, fencing, split brain condition, so the following is more of an explanation. Here we go. -------- Cluster, HA, failover, switchover, scalability -------- An attempted definition of a Cluster: A cluster is a set (2+) server nodes dedicated to keep application services alive, communicating through the cluster software/framework with eachother, test and probe health status of servernodes/services and with quorum based decisions and with switchover/failover techniques keep the application services running on them available. That is, should a node that runs a service unexpectedly lose functionality/connection, the other ones would take over the and run the services, so that availability is guaranteed. To provide availability while strictly sticking to a consistent clusterconfiguration is the main goal of a cluster. At this point we have to add that this defines a HA-cluster, a High-Availability cluster, where the clusternodes are planned to run the services in an active-standby, or failover fashion. An example could be a single instance database. Some applications can be run in a distributed or scalable fashion. In the latter case instances of the application run actively on separate clusternodes serving servicerequests simultaneously. An example for this version could be a webserver that forwards connection requests to many backend servers in a round-robin way. Or a database running in active-active RAC setup. -------- Cluster arhitecture, interconnect, topologies -------- Now, what is a cluster made of? Servers, right. These servers (the clusternodes) need to communicate. This of course happens over the network, usually over dedicated network interfaces interconnecting all the clusternodes. These connection are called interconnects.How many clusternodes are in a cluster? There are different cluster topologies. The most simple one is a clustered pair topology, involving only two clusternodes: There are several more topologies, clicking the image above will take you to the relevant documentation. Also, to answer the question Solaris Cluster allows you to run up to 16 servers in a cluster. Where shall these clusternodes be placed? A very important question. The right answer is: It depends on what you plan to achieve with the cluster. Do you plan to avoid only a server outage? Then you can place them right next to eachother in the datacenter. Do you need to avoid DataCenter outage? In that case of course you should place them at least in different fire zones. Or in two geographically distant DataCenters to avoid disasters like floods, large-scale fires or power outages. We call this a stretched- or campus cluster, the clusternodes being several kilometers away from eachother. To cover really large distances, you probably need to move to a GeoCluster, which is a different kind of animal. What is a geocluster? A Geographic Cluster in Solaris Cluster terms is actually a metacluster between two, separate (locally-HA) clusters. -------- Cluster resource types, agents, resources, resource groups -------- So how does the cluster manage my applications? The cluster needs to start, stop and probe your applications. If you application runs, the cluster needs to check regularly if the application state is healthy, does it respond over the network, does it have all the processes running, etc. This is called probing. If the cluster deems the application is in a faulty state, then it can try to restart it locally or decide to switch (stop on node A, start on node B) the service. Starting, stopping and probing are the three actions that a cluster agent does. There are many different kinds of agents included in Solaris Cluster, but you can build your own too. Examples are an agent that manages (mounts, moves) ZFS filesystems, or the Oracle DB HA agent that cares about the database, or an agent that moves a floating IP address between nodes. There are lots of other agents included for Apache, Tomcat, MySQL, Oracle DB, Oracle Weblogic, Zones, LDoms, NFS, DNS, etc.We also need to clarify the difference between a cluster resource and the cluster resource group.A cluster resource is something that is managed by a cluster agent. Cluster resource types are included in Solaris cluster (see above, e.g. HAStoragePlus, HA-Oracle, LogicalHost). You can group cluster resources into cluster resourcegroups, and switch these groups together from one node to another. To stick to the example above, to move an Oracle DB service from one node to another, you have to switch the group between nodes, and the agents of the cluster resources in the group will do the following: On node A Shut down the DB Unconfigure the LogicalHost IP the DB Listener listens on unmount the filesystem Then, on node B: mount the FS configure the IP startup the DB -------- Voting, Quorum, Split Brain Condition, Fencing, Amnesia -------- How do the clusternodes agree upon their action? How do they decide which node runs what services? Another important question. Running a cluster is a strictly democratic thing.Every node has votes, and you need the majority of votes to have the deciding power. Now, this is usually no problem, clusternodes think very much all alike. Still, every action needs to be governed upon in a productive system, and has to be agreed upon. Agreeing is easy as long as the clusternodes all behave and talk to eachother over the interconnect. But if the interconnect is gone/down, this all gets tricky and confusing. Clusternodes think like this: "My job is to run these services. The other node does not answer my interconnect communication, it must be down. I'd better take control and run the services!". The problem is, as I have already mentioned, clusternodes very much think alike. If the interconnect is gone, they all assume the other node is down, and they all want to mount the data backend, enable the IP and run the database. Double IPs, double mounts, double DB instances - now that is trouble. Also, in a 2-node cluster they both have only 50% of the votes, that is, they themselves alone are not allowed to run a cluster. This is where you need a quorum device. According to Wikipedia, the "requirement for a quorum is protection against totally unrepresentative action in the name of the body by an unduly small number of persons.". They need additional votes to run the cluster. For this requirement a 2-node cluster needs a quorum device or a quorum server. If the interconnect is gone, (this is what we call a split brain condition) both nodes start to race and try to reserve the quorum device to themselves. They do this, because the quorum device bears an additional vote, that could ensure majority (50% +1). The one that manages to lock the quorum device (e.g. if it's an FC LUN, it SCSI reserves it) wins the right to build/run a cluster, the other one - realizing he was late - panics/reboots to ensure the cluster config stays consistent. Losing the interconnect isn't only endangering the availability of services, but it also endangers the cluster configuration consistence. Just imagine node A being down and during that the cluster configuration changes. Now node B goes down, and node A comes up. It isn't uptodate about the cluster configuration's changes so it will refuse to start a cluster, since that would lead to cluster amnesia, that is the cluster had some changes, but now runs with an older cluster configuration repository state, that is it's like it forgot about the changes. Also, to ensure application data consistence, the clusternode that wins the race makes sure that a server that isn't part of or can't currently join the cluster can access the devices. This procedure is called fencing. This usually happens to storage LUNs via SCSI reservation. Now, another important question: Where do I place the quorum disk? Imagine having two sites, two separate datacenters, one in the north of the city and the other one in the south part of it. You run a stretched cluster in the clustered pair topology. Where do you place the quorum disk/server? If you put it into the north DC, and that gets hit by a meteor, you lose one clusternode, which isn't a problem, but you also lose your quorum, and the south clusternode can't keep the cluster running lacking the votes. This problem can't be solved with two sites and a campus cluster. You will need a third site to either place the quorum server to, or a third clusternode. Otherwise, lacking majority, if you lose the site that had your quorum, you lose the cluster. Okay, we covered the very basics. We haven't talked about virtualization support, CCR, ClusterFilesystems, DID devices, affinities, storage-replication, management tools, upgrade procedures - should those be interesting for you, let me know in the comments, along with any other questions. Given enough demand I'd be glad to write a followup post too. Now I really want to move on to the second part in the series: ClusterInstallation. Oh, as for additional source of information, I recommend the documentation: http://docs.oracle.com/cd/E23623_01/index.html, and the OTN Oracle Solaris Cluster site: http://www.oracle.com/technetwork/server-storage/solaris-cluster/index.html

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Looking into Entity Framework Code First Migrations

- by nikolaosk

In this post I will introduce you to Code First Migrations, an Entity Framework feature introduced in version 4.3 back in February of 2012.I have extensively covered Entity Framework in this blog. Please find my other Entity Framework posts here . Before the addition of Code First Migrations (4.1,4.2 versions), Code First database initialisation meant that Code First would create the database if it does not exist (the default behaviour - CreateDatabaseIfNotExists). The other pattern we could use is DropCreateDatabaseIfModelChanges which means that Entity Framework, will drop the database if it realises that model has changes since the last time it created the database.The final pattern is DropCreateDatabaseAlways which means that Code First will recreate the database every time one runs the application.That is of course fine for the development database but totally unacceptable and catastrophic when you have a production database. We cannot lose our data because of the work that Code First works.Migrations solve this problem.With migrations we can modify the database without completely dropping it.We can modify the database schema to reflect the changes to the model without losing data.In version EF 5.0 migrations are fully included and supported. I will demonstrate migrations with a hands-on example.Let me say a few words first about Entity Framework first. The .Net framework provides support for Object Relational Mappingthrough EF. So EF is a an ORM tool and it is now the main data access technology that microsoft works on. I use it quite extensively in my projects. Through EF we have many things out of the box provided for us. We have the automatic generation of SQL code.It maps relational data to strongly types objects.All the changes made to the objects in the memory are persisted in a transactional way back to the data store. You can find in this post an example on how to use the Entity Framework to retrieve data from an SQL Server Database using the "Database/Schema First" approach.In this approach we make all the changes at the database level and then we update the model with those changes. In this post you can see an example on how to use the "Model First" approach when working with ASP.Net and the Entity Framework.This model was firstly introduced in EF version 4.0 and we could start with a blank model and then create a database from that model.When we made changes to the model , we could recreate the database from the new model. The Code First approach is the more code-centric than the other two. Basically we write POCO classes and then we persist to a database using something called DBContext.Code First relies on DbContext. We create 2,3 classes (e.g Person,Product) with properties and then these classes interact with the DbContext class we can create a new database based upon our POCOS classes and have tables generated from those classes.We do not have an .edmx file in this approach.By using this approach we can write much easier unit tests.DbContext is a new context class and is smaller,lightweight wrapper for the main context class which is ObjectContext (Schema First and Model First).Let's move on to our hands-on example.I have installed VS 2012 Ultimate edition in my Windows 8 machine. 1) Create an empty asp.net web application. Give your application a suitable name. Choose C# as the development language2) Add a new web form item in your application. Leave the default name.3) Create a new folder. Name it CodeFirst .4) Add a new item in your application, a class file. Name it Footballer.cs. This is going to be a simple POCO class.Place this class file in the CodeFirst folder.The code follows public class Footballer { public int FootballerID { get; set; } public string FirstName { get; set; } public string LastName { get; set; } public double Weight { get; set; } public double Height { get; set; } }5) We will have to add EF 5.0 to our project. Right-click on the project in the Solution Explorer and select Manage NuGet Packages... for it.In the window that will pop up search for Entity Framework and install it.Have a look at the picture below If you want to find out if indeed EF version is 5.0 version is installed have a look at the References. Have a look at the picture below to see what you will see if you have installed everything correctly.Have a look at the picture below 6) Then we need to create a context class that inherits from DbContext.Add a new class to the CodeFirst folder.Name it FootballerDBContext.Now that we have the entity classes created, we must let the model know.I will have to use the DbSet<T> property.The code for this class follows public class FootballerDBContext:DbContext { public DbSet<Footballer> Footballers { get; set; } } Do not forget to add (using System.Data.Entity;) in the beginning of the class file 7) We must take care of the connection string. It is very easy to create one in the web.config.It does not matter that we do not have a database yet.When we run the DbContext and query against it , it will use a connection string in the web.config and will create the database based on the classes.I will use the name "FootballTraining" for the database.In my case the connection string inside the web.config, looks like this <connectionStrings> <add name="CodeFirstDBContext" connectionString="server=.;integrated security=true; database=FootballTraining" providerName="System.Data.SqlClient"/> </connectionStrings>8) Now it is time to create Linq to Entities queries to retrieve data from the database . Add a new class to your application in the CodeFirst folder.Name the file DALfootballer.csWe will create a simple public method to retrieve the footballers. The code for the class followspublic class DALfootballer { FootballerDBContext ctx = new FootballerDBContext(); public List<Footballer> GetFootballers() { var query = from player in ctx.Footballers select player; return query.ToList(); } } 9) Place a GridView control on the Default.aspx page and leave the default name.Add an ObjectDataSource control on the Default.aspx page and leave the default name. Set the DatasourceID property of the GridView control to the ID of the ObjectDataSource control.(DataSourceID="ObjectDataSource1" ). Let's configure the ObjectDataSource control. Click on the smart tag item of the ObjectDataSource control and select Configure Data Source. In the Wizzard that pops up select the DALFootballer class and then in the next step choose the GetFootballers() method.Click Finish to complete the steps of the wizzard.Build and Run your application. 10) Obviously you will not see any records coming back from your database, because we have not inserted anything. The database is created, though.Have a look at the picture below. 11) Now let's change the POCO class. Let's add a new property to the Footballer.cs class. public int Age { get; set; } Build and run your application again. You will receive an error. Have a look at the picture below 12) That was to be expected.EF Code First Migrations is not activated by default. We have to activate them manually and configure them according to your needs. We will open the Package Manager Console from the Tools menu within Visual Studio 2012.Then we will activate the EF Code First Migration Features by writing the command “Enable-Migrations”. Have a look at the picture below. This adds a new folder Migrations in our project. A new auto-generated class Configuration.cs is created.Another class is also created [CURRENTDATE]_InitialCreate.cs and added to our project.The Configuration.cs is shown in the picture below. The [CURRENTDATE]_InitialCreate.cs is shown in the picture below 13) ??w we are ready to migrate the changes in the database. We need to run the Add-Migration Age command in Package Manager ConsoleAdd-Migration will scaffold the next migration based on changes you have made to your model since the last migration was created.In the Migrations folder, the file 201211201231066_Age.cs is created.Have a look at the picture below to see the newly generated file and its contents. Now we can run the Update-Database command in Package Manager Console .See the picture above.Code First Migrations will compare the migrations in our Migrations folder with the ones that have been applied to the database. It will see that the Age migration needs to be applied, and run it.The EFMigrations.CodeFirst.FootballeDBContext database is now updated to include the Age column in the Footballers table.Build and run your application.Everything will work fine now.Have a look at the picture below to see the migrations applied to our table. 14) We may want it to automatically upgrade the database (by applying any pending migrations) when the application launches.Let's add another property to our Poco class. public string TShirtNo { get; set; }We want this change to migrate automatically to the database.We go to the Configuration.cs we enable automatic migrations. public Configuration() { AutomaticMigrationsEnabled = true; } In the Page_Load event handling routine we have to register the MigrateDatabaseToLatestVersion database initializer. A database initializer simply contains some logic that is used to make sure the database is setup correctly. protected void Page_Load(object sender, EventArgs e) { Database.SetInitializer(new MigrateDatabaseToLatestVersion<FootballerDBContext, Configuration>()); } Build and run your application. It will work fine. Have a look at the picture below to see the migrations applied to our table in the database. Hope it helps!!!

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Windows 8 Will be Here Tomorrow; but Should Silverlight be Gone Today?

- by andrewbrust

The software industry lives within an interesting paradox. IT in the enterprise moves slowly and cautiously, upgrading only when safe and necessary. IT interests intentionally live in the past. On the other hand, developers, and Independent Software Vendors (ISVs) not only want to use the latest and greatest technologies, but this constituency prides itself on gauging tech’s future, and basing its present-day strategy upon it. Normally, we as an industry manage this paradox with a shrug of the shoulder and musings along the lines of “it takes all kinds.” Different subcultures have different tendencies. So be it. Microsoft, with its Windows operating system (OS), can’t take such a laissez-faire view of the world though. Redmond relies on IT to deploy Windows and (at the very least) influence its procurement, but it also relies on developers to build software for Windows, especially software that has a dependency on features in new versions of the OS. It must indulge and nourish developers’ fetish for an early birthing of the next generation of software, even as it acknowledges the IT reality that the next wave will arrive on-schedule in Redmond and will travel very slowly to end users. With the move to Windows 8, and the corresponding shift in application development models, this paradox is certainly in place. On the one hand, the next version of Windows is widely expected sometime in 2012, and its full-scale deployment will likely push into 2014 or even later. Meanwhile, there’s a technology that runs on today’s Windows 7, will continue to run in the desktop mode of Windows 8 (the next version’s codename), and provides absolutely the best architectural bridge to the Windows 8 Metro-style application development stack. That technology is Silverlight. And given what we now know about Windows 8, one might think, as I do, that Microsoft ecosystem developers should be flocking to it. But because developers are trying to get a jump on the future, and since many of them believe the impending v5.0 release of Silverlight will be the technology’s last, not everyone is flocking to it; in fact some are fleeing from it. Is this sensible? Is it not unprecedented? What options does it lead to? What’s the right way to think about the situation? Is v5.0 really the last major version of the technology called Silverlight? We don’t know. But Scott Guthrie, the “father” and champion of the technology, left the Developer Division of Microsoft months ago to work on the Windows Azure team, and he took his people with him. John Papa, who was a very influential Redmond-based evangelist for Silverlight (and is a Visual Studio Magazine author), left Microsoft completely. About a year ago, when initial suspicion of Silverlight’s demise reached significant magnitude, Papa interviewed Guthrie on video and their discussion served to dispel developers’ fears; but now they’ve moved on. So read into that what you will and let’s suppose, for the sake of argument, speculation that Silverlight’s days of major revision and iteration are over now is correct. Let’s assume the shine and glimmer has dimmed. Let’s assume that any Silverlight application written today, and that therefore any investment of financial and human resources made in Silverlight development today, is destined for rework and extra investment in a few years, if the application’s platform needs to stay current. Is this really so different from any technology investment we make? Every framework, language, runtime and operating system is subject to change, to improvement, to flux and, yes, to obsolescence. What differs from project to project, is how near-term that obsolescence is and how disruptive the change will be. The shift from .NET 1.1. to 2.0 was incremental. Some of the further changes were too. But the switch from Windows Forms to WPF was major, and the change from ASP.NET Web Services (asmx) to Windows Communication Foundation (WCF) was downright fundamental. Meanwhile, the transition to the .NET development model for Windows 8 Metro-style applications is actually quite gentle. The finer points of this subject are covered nicely in Magenic’s excellent white paper “Assessing the Windows 8 Development Platform.” As the authors of that paper (including Rocky Lhotka) point out, Silverlight code won’t just “port” to Windows 8. And, no, Silverlight user interfaces won’t either; Metro always supports XAML, but that relationship is not commutative. But the concepts, the syntax, the architecture and developers’ skills map from Silverlight to Windows 8 Metro and the Windows Runtime (WinRT) very nicely. That’s not a coincidence. It’s not an accident. This is a protected transition. It’s not a slap in the face. There are few things that are unnerving about this transition, which make it seem markedly different from others: The assumed end of the road for Silverlight is something many think they can see. Instead of being ignorant of the technology’s expiration date, we believe we know it. If ignorance is bliss, it would seem our situation lacks it. The new technology involving WinRT and Metro involves a name change from Silverlight. .NET, which underlies both Silverlight and the XAML approach to WinRT development, has just about reached 10 years of age. That’s equivalent to 80 in human years, or so many fear. My take is that the combination of these three factors has contributed to what for many is a psychologically compelling case that Silverlight should be abandoned today and HTML 5 (the agnostic kind, not the Windows RT variety) should be embraced in its stead. I understand the logic behind that. I appreciate the preemptive, proactive, vigilant conscientiousness involved in its calculus. But for a great many scenarios, I don’t agree with it. HTML 5 clients, no matter how impressive their interactivity and the emulation of native application interfaces they present may be, are still second-class clients. They are getting better, especially when hardware acceleration and fast processors are involved. But they still lag. They still feel like they’re emulating something, like they’re prototypes, like they’re not comfortable in their own skins. They are based on compromise, and they feel compromised too. HTML 5/JavaScript development tools are getting better, and will get better still, but they are not as productive as tools for other environments, like Flash, like Silverlight or even more primitive tooling for iOS or Android. HTML’s roots as a document markup language, rather than an application interface, create a disconnect that impedes productivity. I do not necessarily think that problem is insurmountable, but it’s here today. If you’re building line-of-business applications, you need a first-class client and you need productivity. Lack of productivity increases your costs and worsens your backlog. A second class client will erode user satisfaction, which is never good. Worse yet, this erosion will be inconspicuous, rather than easily identified and diagnosed, because the inferiority of an HTML 5 client over a native one is hard to identify and, notably, doing so at this juncture in the industry is unpopular. Why would you fault a technology that everyone believes is revolutionary? Instead, user disenchantment will remain latent and yet will add to the malaise caused by slower development. If you’re an ISV and you’re coveting the reach of running multi-platform, it’s a different story. You’ve likely wanted to move to HTML 5 already, and the uncertainty around Silverlight may be the only remaining momentum or pretext you need to make the shift. You’re deploying many more copies of your application than a line-of-business developer is anyway; this makes the economic hit from lower productivity less impactful, and the wider potential installed base might even make it profitable. But no matter who you are, it’s important to take stock of the situation and do it accurately. Continued, but merely incremental changes in a development model lead to conservatism and general lack of innovation in the underlying platform. Periods of stability and equilibrium are necessary, but permanence in that equilibrium leads to loss of platform relevance, market share and utility. Arguably, that’s already happened to Windows. The change Windows 8 brings is necessary and overdue. The marked changes in using .NET if we’re to build applications for the new OS are inevitable. We will ultimately benefit from the change, and what we can reasonably hope for in the interim is a migration path for our code and skills that is navigable, logical and conceptually comfortable. That path takes us to a place called WinRT, rather than a place called Silverlight. But considering everything that is changing for the good, the number of disruptive changes is impressively minimal. The name may be changing, and there may even be some significance to that in terms of Microsoft’s internal management of products and technologies. But as the consumer, you should care about the ingredients, not the name. Turkish coffee and Greek coffee are much the same. Although you’ll find plenty of interested parties who will find the names significant, drinkers of the beverage should enjoy either one. It’s all coffee, it’s all sweet, and you can tell your fortune from the grounds that are left at the end. Back on the software side, it’s all XAML, and C# or VB .NET, and you can make your fortune from the product that comes out at the end. Coffee drinkers wouldn’t switch to tea. Why should XAML developers switch to HTML?

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Making a Case For The Command Line

- by Jesse Taber

Originally posted on: http://geekswithblogs.net/GruffCode/archive/2013/06/30/making-a-case-for-the-command-line.aspxI have had an idea percolating in the back of my mind for over a year now that I’ve just recently started to implement. This idea relates to building out “internal tools” to ease the maintenance and on-going support of a software system. The system that I currently work on is (mostly) web-based, so we traditionally we have built these internal tools in the form of pages within the app that are only accessible by our developers and support personnel. These pages allow us to perform tasks within the system that, for one reason or another, we don’t want to let our end users perform (e.g. mass create/update/delete operations on data, flipping switches that turn paid modules of the system on or off, etc). When we try to build new tools like this we often struggle with the level of effort required to build them. Effort Required Creating a whole new page in an existing web application can be a fairly large undertaking. You need to create the page and ensure it will have a layout that is consistent with the other pages in the app. You need to decide what types of input controls need to go onto the page. You need to ensure that everything uses the same style as the rest of the site. You need to figure out what the text on the page should say. Then, when you figure out that you forgot about an input that should really be present you might have to go back and re-work the entire thing. Oh, and in addition to all of that, you still have to, you know, write the code that actually performs the task. Everything other than the code that performs the task at hand is just overhead. We don’t need a fancy date picker control in a nicely styled page for the vast majority of our internal tools. We don’t even really need a page, for that matter. We just need a way to issue a command to the application and have it, in turn, execute the code that we’ve written to accomplish a given task. All we really need is a simple console application! Plumbing Problems A former co-worker of mine, John Sonmez, always advocated the Unix philosophy for building internal tools: start with something that runs at the command line, and then build a UI on top of that if you need to. John’s idea has a lot of merit, and we tried building out some internal tools as simple Console applications. Unfortunately, this was often easier said that done. Doing a “File –> New Project” to build out a tool for a mature system can be pretty daunting because that new project is totally empty. In our case, the web application code had a lot of of “plumbing” built in: it managed authentication and authorization, it handled database connection management for our multi-tenanted architecture, it managed all of the context that needs to follow a user around the application such as their timezone and regional/language settings. In addition, the configuration file for the web application (a web.config in our case because this is an ASP .NET application) is large and would need to be reproduced into a similar configuration file for a Console application. While most of these problems are could be solved pretty easily with some refactoring of the codebase, building Console applications for internal tools still potentially suffers from one pretty big drawback: you’d have to execute them on a machine with network access to all of the needed resources. Obviously, our web servers can easily communicate the the database servers and can publish messages to our service bus, but the same is not true for all of our developer and support personnel workstations. We could have everyone run these tools remotely via RDP or SSH, but that’s a bit cumbersome and certainly a lot less convenient than having the tools built into the web application that is so easily accessible. Mix and Match So we need a way to build tools that are easily accessible via the web application but also don’t require the overhead of creating a user interface. This is where my idea comes into play: why not just build a command line interface into the web application? If it’s part of the web application we get all of the plumbing that comes along with that code, and we’re executing everything on the web servers which means we’ll have access to any external resources that we might need. Rather than having to incur the overhead of creating a brand new page for each tool that we want to build, we can create one new page that simply accepts a command in text form and executes it as a request on the web server. In this way, we can focus on writing the code to accomplish the task. If the tool ends up being heavily used, then (and only then) should we consider spending the time to build a better user experience around it. To be clear, I’m not trying to downplay the importance of building great user experiences into your system; we should all strive to provide the best UX possible to our end users. I’m only advocating this sort of bare-bones interface for internal consumption by the technical staff that builds and supports the software. This command line interface should be the “back end” to a highly polished and eye-pleasing public face. Implementation As I mentioned at the beginning of this post, this is an idea that I’ve had for awhile but have only recently started building out. I’ve outlined some general guidelines and design goals for this effort as follows: Text in, text out: In the interest of keeping things as simple as possible, I want this interface to be purely text-based. Users will submit commands as plain text, and the application will provide responses in plain text. Obviously this text will be “wrapped” within the context of HTTP requests and responses, but I don’t want to have to think about HTML or CSS when taking input from the user or displaying responses back to the user. Task-oriented code only: After building the initial “harness” for this interface, the only code that should need to be written to create a new internal tool should be code that is expressly needed to accomplish the task that the tool is intended to support. If we want to encourage and enable ourselves to build good tooling, we need to lower the barriers to entry as much as possible. Built-in documentation: One of the great things about most command line utilities is the ‘help’ switch that provides usage guidelines and details about the arguments that the utility accepts. Our web-based command line utility should allow us to build the documentation for these tools directly into the code of the tools themselves. I finally started trying to implement this idea when I heard about a fantastic open-source library called CLAP (Command Line Auto Parser) that lets me meet the guidelines outlined above. CLAP lets you define classes with public methods that can be easily invoked from the command line. Here’s a quick example of the code that would be needed to create a new tool to do something within your system: 1: public class CustomerTools 2: { 3: [Verb] 4: public void UpdateName(int customerId, string firstName, string lastName) 5: { 6: //invoke internal services/domain objects/hwatever to perform update 7: } 8: } This is just a regular class with a single public method (though you could have as many methods as you want). The method is decorated with the ‘Verb’ attribute that tells the CLAP library that it is a method that can be invoked from the command line. Here is how you would invoke that code: Parser.Run(args, new CustomerTools()); Note that ‘args’ is just a string[] that would normally be passed passed in from the static Main method of a Console application. Also, CLAP allows you to pass in multiple classes that define [Verb] methods so you can opt to organize the code that CLAP will invoke in any way that you like. You can invoke this code from a command line application like this: SomeExe UpdateName -customerId:123 -firstName:Jesse -lastName:Taber ‘SomeExe’ in this example just represents the name of .exe that is would be created from our Console application. CLAP then interprets the arguments passed in order to find the method that should be invoked and automatically parses out the parameters that need to be passed in. After a quick spike, I’ve found that invoking the ‘Parser’ class can be done from within the context of a web application just as easily as it can from within the ‘Main’ method entry point of a Console application. There are, however, a few sticking points that I’m working around: Splitting arguments into the ‘args’ array like the command line: When you invoke a standard .NET console application you get the arguments that were passed in by the user split into a handy array (this is the ‘args’ parameter referenced above). Generally speaking they get split by whitespace, but it’s also clever enough to handle things like ignoring whitespace in a phrase that is surrounded by quotes. We’ll need to re-create this logic within our web application so that we can give the ‘args’ value to CLAP just like a console application would. Providing a response to the user: If you were writing a console application, you might just use Console.WriteLine to provide responses to the user as to the progress and eventual outcome of the command. We can’t use Console.WriteLine within a web application, so I’ll need to find another way to provide feedback to the user. Preferably this approach would allow me to use the same handler classes from both a Console application and a web application, so some kind of strategy pattern will likely emerge from this effort. Submitting files: Often an internal tool needs to support doing some kind of operation in bulk, and the easiest way to submit the data needed to support the bulk operation is in a file. Getting the file uploaded and available to the CLAP handler classes will take a little bit of effort. Mimicking the console experience: This isn’t really a requirement so much as a “nice to have”. To start out, the command-line interface in the web application will probably be a single ‘textarea’ control with a button to submit the contents to a handler that will pass it along to CLAP to be parsed and run. I think it would be interesting to use some javascript and CSS trickery to change that page into something with more of a “shell” interface look and feel. I’ll be blogging more about this effort in the future and will include some code snippets (or maybe even a full blown example app) as I progress. I also think that I’ll probably end up either submitting some pull requests to the CLAP project or possibly forking/wrapping it into a more web-friendly package and open sourcing that.

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