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• how can I translate a NSString to NSData? And the data has the same content as the string

  - by someonemaybe

  NSString * theString=@"e88d"; NSData * data; // something I should implement NSLog(@"%@", theString); NSLog(@"%@",[data description]); I want the results of the two printings are the same. AES encryption and decryption: (1).The server: if the plaintext is :@"abcd"; the AES encrypted data(NSData data type) is :"d882830c dc892036 4345839f 13c7516a"; (2).in my local app, my code is : NSData*data=[NSData dataWithContentsOfURL:[NSURL URLWithString:@"http://..."]]; NSString * mystring= [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]; However, to decrypt data successfully, I must got a data(NSData date type) which equals to "d882830c dc892036 4345839f 13c7516a".But it is the mystring (NSString data type) not the data(NSData data type) that equals to the right value. the encryption and decryption function both need a data(NSData data type) as input datas. (NSData*)AES128EncryptWithKey:(NSString*)key; (NSData*)AES128DecryptWithKey:(NSString*)key;

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• adding nodes to a binary search tree randomly deletes nodes

  - by SDLFunTimes

  Hi, stack. I've got a binary tree of type TYPE (TYPE is a typedef of data*) that can add and remove elements. However for some reason certain values added will overwrite previous elements. Here's my code with examples of it inserting without overwriting elements and it not overwriting elements. the data I'm storing: struct data { int number; char *name; }; typedef struct data data; # ifndef TYPE # define TYPE data* # define TYPE_SIZE sizeof(data*) # endif The tree struct: struct Node { TYPE val; struct Node *left; struct Node *rght; }; struct BSTree { struct Node *root; int cnt; }; The comparator for the data. int compare(TYPE left, TYPE right) { int left_len; int right_len; int shortest_string; /* find longest string */ left_len = strlen(left->name); right_len = strlen(right->name); if(right_len < left_len) { shortest_string = right_len; } else { shortest_string = left_len; } /* compare strings */ if(strncmp(left->name, right->name, shortest_string) > 1) { return 1; } else if(strncmp(left->name, right->name, shortest_string) < 1) { return -1; } else { /* strings are equal */ if(left->number > right->number) { return 1; } else if(left->number < right->number) { return -1; } else { return 0; } } } And the add method struct Node* _addNode(struct Node* cur, TYPE val) { if(cur == NULL) { /* no root has been made */ cur = _createNode(val); return cur; } else { int cmp; cmp = compare(cur->val, val); if(cmp == -1) { /* go left */ if(cur->left == NULL) { printf("adding on left node val %d\n", cur->val->number); cur->left = _createNode(val); } else { return _addNode(cur->left, val); } } else if(cmp >= 0) { /* go right */ if(cur->rght == NULL) { printf("adding on right node val %d\n", cur->val->number); cur->rght = _createNode(val); } else { return _addNode(cur->rght, val); } } return cur; } } void addBSTree(struct BSTree *tree, TYPE val) { tree->root = _addNode(tree->root, val); tree->cnt++; } The function to print the tree: void printTree(struct Node *cur) { if (cur == 0) { printf("\n"); } else { printf("("); printTree(cur->left); printf(" %s, %d ", cur->val->name, cur->val->number); printTree(cur->rght); printf(")\n"); } } Here's an example of some data that will overwrite previous elements: struct BSTree myTree; struct data myData1, myData2, myData3; myData1.number = 5; myData1.name = "rooty"; myData2.number = 1; myData2.name = "lefty"; myData3.number = 10; myData3.name = "righty"; initBSTree(&myTree); addBSTree(&myTree, &myData1); addBSTree(&myTree, &myData2); addBSTree(&myTree, &myData3); printTree(myTree.root); Which will print: (( righty, 10 ) lefty, 1 ) Finally here's some test data that will go in the exact same spot as the previous data, but this time no data is overwritten: struct BSTree myTree; struct data myData1, myData2, myData3; myData1.number = 5; myData1.name = "i"; myData2.number = 5; myData2.name = "h"; myData3.number = 5; myData3.name = "j"; initBSTree(&myTree); addBSTree(&myTree, &myData1); addBSTree(&myTree, &myData2); addBSTree(&myTree, &myData3); printTree(myTree.root); Which prints: (( j, 5 ) i, 5 ( h, 5 ) ) Does anyone know what might be going wrong? Sorry if this post was kind of long.

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• Invoke "internal extern" constructor using reflections

  - by Riz

  Hi, I have following class (as seen through reflector) public class W : IDisposable { public W(string s); public W(string s, byte[] data); // more constructors [MethodImpl(MethodImplOptions.InternalCall)] internal extern W(string s, int i); public static W Func(string s, int i); } I am trying to call "internal extern" constructor or Func using reflections MethodInfo dynMethod = typeof(W).GetMethod("Func", BindingFlags.Static); object[] argVals = new object[] { "hi", 1 }; dynMethod.Invoke(null, argVals); and Type type = typeof(W); Type[] argTypes = new Type[] { typeof(System.String), typeof(System.Int32) }; ConstructorInfo cInfo = type.GetConstructor(BindingFlags.InvokeMethod | BindingFlags.NonPublic, null, argTypes, null); object[] argVals = new object[] { "hi", 1 }; dynMethod.Invoke(null, argVals); unfortunantly both variants rise NullReferenceException when trying to Invoke, so, I must be doing something wrong?

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• WPF: Timers

  - by Ilya Verbitskiy

  I believe, once your WPF application will need to execute something periodically, and today I would like to discuss how to do that. There are two possible solutions. You can use classical System.Threading.Timer class or System.Windows.Threading.DispatcherTimer class, which is the part of WPF. I have created an application to show you how to use the API.     Let’s take a look how you can implement timer using System.Threading.Timer class. First of all, it has to be initialized.   1: private Timer timer; 2:   3: public MainWindow() 4: { 5: // Form initialization code 6: 7: timer = new Timer(OnTimer, null, Timeout.InfiniteTimeSpan, Timeout.InfiniteTimeSpan); 8: }   Timer’s constructor accepts four parameters. The first one is the callback method which is executed when timer ticks. I will show it to you soon. The second parameter is a state which is passed to the callback. It is null because there is nothing to pass this time. The third parameter is the amount of time to delay before the callback parameter invokes its methods. I use System.Threading.Timeout helper class to represent infinite timeout which simply means the timer is not going to start at the moment. And the final fourth parameter represents the time interval between invocations of the methods referenced by callback. Infinite timeout timespan means the callback method will be executed just once. Well, the timer has been created. Let’s take a look how you can start the timer.   1: private void StartTimer(object sender, RoutedEventArgs e) 2: { 3: timer.Change(TimeSpan.Zero, new TimeSpan(0, 0, 1)); 4:   5: // Disable the start buttons and enable the reset button. 6: }   The timer is started by calling its Change method. It accepts two arguments: the amount of time to delay before the invoking the callback method and the time interval between invocations of the callback. TimeSpan.Zero means we start the timer immediately and TimeSpan(0, 0, 1) tells the timer to tick every second. There is one method hasn’t been shown yet. This is the callback method OnTimer which does a simple task: it shows current time in the center of the screen. Unfortunately you cannot simple write something like this:   1: clock.Content = DateTime.Now.ToString("hh:mm:ss");   The reason is Timer runs callback method on a separate thread, and it is not possible to access GUI controls from a non-GUI thread. You can avoid the problem using System.Windows.Threading.Dispatcher class.   1: private void OnTimer(object state) 2: { 3: Dispatcher.Invoke(() => ShowTime()); 4: } 5:   6: private void ShowTime() 7: { 8: clock.Content = DateTime.Now.ToString("hh:mm:ss"); 9: }   You can build similar application using System.Windows.Threading.DispatcherTimer class. The class represents a timer which is integrated into the Dispatcher queue. It means that your callback method is executed on GUI thread and you can write a code which updates your GUI components directly.   1: private DispatcherTimer dispatcherTimer; 2:   3: public MainWindow() 4: { 5: // Form initialization code 6:   7: dispatcherTimer = new DispatcherTimer { Interval = new TimeSpan(0, 0, 1) }; 8: dispatcherTimer.Tick += OnDispatcherTimer; 9: } Dispatcher timer has nicer and cleaner API. All you need is to specify tick interval and Tick event handler. The you just call Start method to start the timer.   private void StartDispatcher(object sender, RoutedEventArgs e) { dispatcherTimer.Start(); // Disable the start buttons and enable the reset button. } And, since the Tick event handler is executed on GUI thread, the code which sets the actual time is straightforward.   1: private void OnDispatcherTimer(object sender, EventArgs e) 2: { 3: ShowTime(); 4: } We’re almost done. Let’s take a look how to stop the timers. It is easy with the Dispatcher Timer.   1: dispatcherTimer.Stop(); And slightly more complicated with the Timer. You should use Change method again.   1: timer.Change(Timeout.InfiniteTimeSpan, Timeout.InfiniteTimeSpan); What is the best way to add timer into an application? The Dispatcher Timer has simple interface, but its advantages are disadvantages at the same time. You should not use it if your Tick event handler executes time-consuming operations. It freezes your window which it is executing the event handler method. You should think about using System.Threading.Timer in this case. The code is available on GitHub.

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• How to Redraw or Refresh a screen

  - by viky

  I am working on a wpf application. Here I need to use System.Windows.Forms.FolderBrowserDialog in my Wpf application. System.Windows.Forms.FolderBrowserDialog openFolderBrowser = new System.Windows.Forms.FolderBrowserDialog(); openFolderBrowser.Description = "Select Resource Path:"; openFolderBrowser.RootFolder = Environment.SpecialFolder.MyComputer; if (openFolderBrowser.ShowDialog() == System.Windows.Forms.DialogResult.OK) { //some logic } when I select a Folder and click OK, I launch another System.Windows.Forms.FolderBrowserDialog with same code, My problem is when I select a Folder and click OK, the shadow of FolderBrowserDialog remains on the screen(means my screen doesn't refresh). I need to minimize or resize it in order to remove the shadow of FolderBrowserDialog. How can I solvet his issue? Any help plz?

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• ASP.NET MVC SSL POST Error

  - by RyanFetz

  I have a Logon page in a MVC (1.0) application that I am securing with SSL, I have an attribute that inspects the request for the page and redirects to a https uri when it is requested with http. This all works, however when I post the form content i get the following error: The parameters dictionary contains a null entry for parameter 'rememberMe' of non-nullable type 'System.Boolean' for method 'System.Web.Mvc.ActionResult LogOn(System.String, System.String, Boolean, System.String)' in 'DAC.US.Web.Portal.Controllers.AccountController'. To make a parameter optional its type should be either a reference type or a Nullable type. Parameter name: parameters here is the controller code... // // GET: /Account/LogOn [RequiresSSL] public ActionResult LogOn(string ReturnUrl) { if (TempData["Message"] != null) ViewData["Message"] = TempData["Message"]; TempData["Message"] = null; ViewData["ReturnUrl"] = ReturnUrl ?? "/Home"; return View(); } Again, the RequireSSL Attribute works, but the POST from that SSL uri does not. What is not working?

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• How do you use the LINQ to SQL designer to generate accessor methods for subclasses?

  - by Pricey

  Above is the LINQ to SQL designer view for my data context. Below is the relevant code: public System.Data.Linq.Table<ActivityBase> ActivityBases { get { return this.GetTable<ActivityBase>(); } } ... [Table(Name="dbo.Activities")] [InheritanceMapping(Code="1", Type=typeof(ActivityBase), IsDefault=true)] [InheritanceMapping(Code="2", Type=typeof(Project))] [InheritanceMapping(Code="3", Type=typeof(ProjectActivity))] [InheritanceMapping(Code="5", Type=typeof(Task))] [InheritanceMapping(Code="4", Type=typeof(Activity))] public abstract partial class ActivityBase : INotifyPropertyChanging, INotifyPropertyChanged { ... Is there a way to generate accessor methods for the subclasses as shown in the inheritance mapping above (Project, Task, etc...) without doing it manually? I added them manually but then a change in the designer overwrites any manual changes. Am i doing this wrong? should I not be making accessors for the sub classes? filtering from ActivityBase seems worse to me. Thanks for any help on this.

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• Using jQuery for client side validation in MVC2 RTM

  - by tigermain

  Scott Gu's tutorial on Model validation gets us all set up with the MS client side validation using the following scripts: <script src="../../Scripts/jquery.validate.min.js" type="text/javascript"></script> <script src="../../Scripts/MicrosoftMvcValidation.js" type="text/javascript"></script> However I've seen various posts allowing us to utilise jQuery instead with the following code: <script src="https://ajax.microsoft.com/ajax/jquery/jquery-1.4.2.min.js" type="text/javascript"></script> <script src="https://ajax.microsoft.com/ajax/jQuery.Validate/1.6/jQuery.Validate.min.js" type="text/javascript"></script> <script src="<%= Url.Content("~/scripts/MicrosoftMvcJQueryValidation.js") %>" type="text/javascript"></script> However MicrosoftMvcJQueryValidation.js does not ship with the solution and from what I read it should be part of the Futures pack which is no longer available on CodePlex. I managed to find a version alongside jQuery 1.3.2 but it does not work. What is the forward going solution!?

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• Issue converting Sitecore Item[] using ToList<T>

  - by philba888

  Working with Sitecore and Linq extensions. I am trying to convert to from an item array to the list using the following piece of code: Item variationsFolder = masterDB.SelectSingleItem(VariationsFolderID.ToString()); List<Item> variationList = variationsFolder.GetChildren().ToList<Item>(); However I keep getting this error whenever I try to build: 'Sitecore.Collections.ChildList' does not contain a definition for 'ToList' and the best extension method overload 'System.Linq.Enumerable.ToList<TSource>(System.Collections.Generic.IEnumerable<TSource>)' has some invalid arguments I have the following usings: using System.Linq; using System.Xml.Linq; Am referencing: System.Core I've just copied this code from another location, so it should work fine, can only think that there is something simple (like a reference or something that I am missing).

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• Simple, non-blocking way to sleep?

  - by OverTheRainbow

  Hello I googled for this and read some threads here, but I haven't found a simple way to have a VB.Net application sleep for a little while and still keep the application responsive: Imports System.Net Imports System.IO Imports System.Text Imports System.Text.RegularExpressions Imports System.Threading.Thread [...] 'How to keep screen frop freezing? While True ListBox1.Items.Clear() ListBox1.Items.Add("blah") 'Not much difference ListBox1.Refresh() 'Wait 1mn Sleep(60000) End While Is there really no simple, non-blocking solution to have a VB.Net application wait for a few seconds? Thank you.

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• How to Uncheck A radio button

  - by user281867

  Hi, I have two forms, one with a radio button that users must select to edit. [form name="A"] [input type="radio" name="BookItem" value="1" /] [input type="radio" name="BookItem" value="2" /] [input type="radio" name="BookItem" value="3" /] [form] After "BookItem" is selected from form (A) I call the $("#EditFormWrapper").load("callEditData.cfm? ID="+ID); function to load the second form (B) [form id="editForm" name="B"] 2 Hours AM 2 Hours PM 2 Hours AM 2 Hours PM [input type="image" src="images/submit-btn.gif" id="addBTN" name="addBTN" class="buttons" alt="SubmitRrequest" /] [input type="image" src="images/cancel-btn.gif" id="editBTNcancel" name="editBTNcancel" class="buttons" alt="Cancel Request" /] [/form] I want to uncheck the radio button on form (A) when user click on cancel button (editBTNcancel) in form(B). Here s my script: $("#editBTNcancel").live("click", function(event){ event.preventDefault(); $("#EditFormWrapper").slideUp("fast").empty(); //$('.TOR2Hours').removeAttr('checked'); $('.TOR2Hours').attr('checked', false); }); I hope I clearly state my problem, any suggestion would be greatly appreciated!

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• Implicit typing of arrays that implement interfaces

  - by Sir Psycho

  Hi, I was under the impression that the C# compiler will implicitly type an array based off a type that they can all be implicitly converted to. The compiler generates No best type found for implicitly-typed array public interface ISomething {} public interface ISomething2 {} public interface ISomething3 {} public class Foo : ISomething { } public class Bar : ISomething, ISomething2 { } public class Car : ISomething, ISomething3 { } void Main() { var obj1 = new Foo(); var obj2 = new Bar(); var obj3 = new Car(); var objects= new [] { obj1, obj2, obj3 }; } I know that the way to correct this is to declare the type like: new ISomething [] { obj1, ...} But I'm after an under the covers type help here :-) Thanks

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• How to be sure that my MVC project is runting on the correct version after upgrade to vs2010?

  - by Stephane

  I just installed visual studio 2010 and upgraded my MVC project (which was running on MVC RC2 in visual studio 2008). visual studio 2010 updated every project file to target the framework 4.0. But the system.web.dll is pointing to C:\Program Files (x86)\Microsoft ASP.NET\ASP.NET MVC 2\Assemblies\System.Web.Mvc.dll in VS2010 object browser, I have every dll showing up in multiple versions as expected (3.5.0.0 and 4.0.0.0) except for the System.Web.Mvc dll which doesn't show any version and points to the path I mentioned above. Isn't this namespace point to the Framework folder like the System.Web namespace? C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\System.Web.dll

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• CruiseControl Console error message when parsing XML

  - by jarad

  I have CruiseControl(1.5) running in Win2k8R2 and svn(1.6.9) The error happens on a successful build after nant(0.86) Timeout(600 seconds). When I check the build dir everything is built correctly but CruiseControl Dashboard report Exception Here is the error shown in console: [:DEBUG] Exception: System.Xml.XmlException: The ',' character, hexadecimal value 0x2C, cannot be included in a name. Line 5544, position 274. at System.Xml.XmlTextReaderImpl.Throw(Exception e) at System.Xml.XmlTextReaderImpl.ParseElement() at System.Xml.XmlTextReaderImpl.ParseDocumentContent() at System.Xml.XmlWriter.WriteNode(XmlReader reader, Boolean defattr) at ThoughtWorks.CruiseControl.Core.Util.XmlFragmentWriter.WriteNode(XmlReader reader, Boolean defattr) at ThoughtWorks.CruiseControl.Core.Util.XmlFragmentWriter.WriteNode(String xml)

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• Call methods in main method

  - by Niloo

  this is my main method that gets 3 integers from command line and I parse then in my validating method. However I have one operation method that calls 3 other methods, but i don't know what type of data and howmany I have to put in my operatinMethod() " cuase switch only gets one); AND also in my mainMethod() for calling the operationMehod(); itself? please let me know if i'm not clear? Thanx! main method: public class test { // Global Constants final static int MIN_NUMBER = 1; final static int MAX_PRIME = 10000; final static int MAX_FACTORIAL = 12; final static int MAX_LEAPYEAR = 4000; //Global Variables static int a,b,c; public static void main (String[] args) { for(int i =0; i< args.length; i++){} if(validateInput(args[0],args[1],args[2])){ performOperations(); } } //Validate User Input public static boolean validateInput(String num1,String num2,String num3){ boolean isValid = false; try{ try{ try{ a = Integer.parseInt(num1); if(!withinRange(a,MIN_NUMBER, MAX_PRIME)) { System.out.println("The entered value " + num1 +" is out of range [1 TO 10000]."); } isValid = true; } catch(Exception ex) { System.out.println("The entered value " + num1 + " is not a valid integer. Please try again."); } b = Integer.parseInt(num2); if(!withinRange(b,MIN_NUMBER, MAX_FACTORIAL)) { System.out.println("The entered value " + num2 +" is out of range [1 TO 12]."); } isValid = true; } catch(Exception ex) { System.out.println("The entered value " + num2 + " is not a valid integer. Please try again."); } c = Integer.parseInt(num3); if(!withinRange(c,MIN_NUMBER, MAX_LEAPYEAR)) { System.out.println("The entered value " + num3 +" is out of range [1 TO 4000]."); } isValid = true; } catch(Exception ex) { System.out.println("The entered value " + num3 + " is not a valid integer. Please try again."); } return isValid; } //Check the value within the specified range private static boolean withinRange(int userInput ,int min, int max){ boolean isInRange = true; if(userInput < min || userInput > max){ isInRange = false; } return isInRange; } //Perform operations private static void performOperations(int userInput) { switch(userInput) { case 1: // count Prime numbers countPrimes(a); break; case 2: // Calculate factorial getFactorial(b); break; case 3: // find Leap year isLeapYear(c); break; } } // Verify Prime Number private static boolean isPrime(int prime) { for(int i = 2; i <= Math.sqrt(prime) ; i++) { if ((prime % i) == 0) { return false; } } return true; } // Calculate Prime private static int countPrimes(int userInput){ int count =0; for(int i=userInput; i<=MAX_PRIME; i++) { if(isPrime(i)){ count++; } } System.out.println("Exactly "+ count + " prime numbers exist between "+ a + " and 10,000."); return count; } // Calculate the factorial value private static int getFactorial(int userInput){ int ans = userInput; if(userInput >1 ){ ans*= (getFactorial(userInput-1)); //System.out.println("The value of "+ b +"! is "+ getFactorial(userInput)); } return ans; } // Determine whether the integer represents a leap year private static boolean isLeapYear(int userInput){ if (userInput % 4 == 0 && userInput % 400 == 0 && userInput % 100 ==0){ System.out.println("The year "+ c +" is a leap year"); } else { System.out.println("The year "+ c +" is a not leap year"); } return false; } }

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• Updates to NSDictionary attribute in CoreData not saving

  - by sfkaos

  I have created an Entity in CoreData that includes a Transformable attribute type implemented as an NSDictionary. The NSDictionary attribute only contains values of a custom class. The properties of the custom class are all of type NSString. The custom class complies with NSCoding implementing: -(void)encodeWithCoder:(NSCoder*)coder; -(id)initWithCoder:(NSCoder *)coder When saving the Entity for the first time all attributes including the Transformable (NSDictionary) type are properly saved in the DB. When the same Entity is fetched from the DB and updated (including the Transformable attribute) it seems to be updated properly. However, when the app is closed and then reopened fetching the Entity does not show the updated Transformable attribute-type though the rest of the attributes of type NSDate and NSString are up-to-date. The Transformable attribute is the original saved value not the updated value. Is this a problem with KVO or am I missing something else when trying to save an NSDictionary filled with a custom class to CoreData?

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• Python: Why can't I use `super` on a class?

  - by cool-RR

  Why can't I use super to get a method of a class's superclass? Example: Python 3.1.3 >>> class A(object): ... def my_method(self): pass >>> class B(A): ... def my_method(self): pass >>> super(B).my_method Traceback (most recent call last): File "<pyshell#2>", line 1, in <module> super(B).my_method AttributeError: 'super' object has no attribute 'my_method' (Of course this is a trivial case where I could just do A.my_method, but I needed this for a case of diamond-inheritance.) According to super's documentation, it seems like what I want should be possible. This is super's documentation: (Emphasis mine) super() - same as super(__class__, <first argument>) super(type) - unbound super object super(type, obj) - bound super object; requires isinstance(obj, type) super(type, type2) - bound super object; requires issubclass(type2, type) [non-relevant examples redacted]

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• Implementing synchronous MediaTypeFormatters in ASP.NET Web API

  - by cibrax

  One of main characteristics of MediaTypeFormatter’s in ASP.NET Web API is that they leverage the Task Parallel Library (TPL) for reading or writing an model into an stream. When you derive your class from the base class MediaTypeFormatter, you have to either implement the WriteToStreamAsync or ReadFromStreamAsync methods for writing or reading a model from a stream respectively. These two methods return a Task, which internally does all the serialization work, as it is illustrated bellow. public abstract class MediaTypeFormatter { public virtual Task WriteToStreamAsync(Type type, object value, Stream writeStream, HttpContent content, TransportContext transportContext); public virtual Task<object> ReadFromStreamAsync(Type type, Stream readStream, HttpContent content, IFormatterLogger formatterLogger); }   .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } However, most of the times, serialization is a safe operation that can be done synchronously. In fact, many of the serializer classes you will find in the .NET framework only provide sync methods. So the question is, how you can transform that synchronous work into a Task ?. Creating a new task using the method Task.Factory.StartNew for doing all the serialization work would be probably the typical answer. That would work, as a new task is going to be scheduled. However, that might involve some unnecessary context switches, which are out of our control and might be affect performance on server code specially.   If you take a look at the source code of the MediaTypeFormatters shipped as part of the framework, you will notice that they actually using another pattern, which uses a TaskCompletionSource class. public Task WriteToStreamAsync(Type type, object value, Stream writeStream, HttpContent content, TransportContext transportContext) {   var tsc = new TaskCompletionSource<AsyncVoid>(); tsc.SetResult(default(AsyncVoid));   //Do all the serialization work here synchronously   return tsc.Task; }   /// <summary> /// Used as the T in a "conversion" of a Task into a Task{T} /// </summary> private struct AsyncVoid { } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } They are basically doing all the serialization work synchronously and using a TaskCompletionSource for returning a task already done. To conclude this post, this is another approach you might want to consider when using serializers that are not compatible with an async model. Update: Henrik Nielsen from the ASP.NET team pointed out the existence of a built-in media type formatter for writing sync formatters. BufferedMediaTypeFormatter http://t.co/FxOfeI5x

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• typeid , dynamic casting (upcast) and templates

  - by David

  Hello, I have few questions regarding dynamic casting , typeid() and templates 1) How come typeid does not require RTTI ? 2) dynamic_cast on polymorphic type: When I do downcast (Base to Derive) with RTTI - compilation passes When RTTI is off - I get a warning (warning C4541: 'dynamic_cast' used on polymorphic type 'CBase' with /GR-; unpredictable behavior may result) When I do upcast (Derive to Base), with or without RTTI - compilation passes smoothly What I don't understand is why when I do upcast and RTTI is off - I don't get any warning/error! 3) dynamic_cast on NON polymorphic type: When I do downcast with or without RTTI - compilation fails (error C2683: 'dynamic_cast' : 'CBase' is not a polymorphic type) BUT When I do upcast with or without RTTI - compilation passes smoothly. How come on upcast on NON polymorphic type passes w/o RTTI ? 4) Does 'inline' in front of a template function has any effect, i.e. when the compiler compiles the function and see it is 'inline' it will actually treat the function as inline or it is ignored? Thank you very much for the assistance David

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• Is wordpress a good platform for webapp development?

  - by darlinton

  I am planning a webapp to control bank paying orders. In a quick review, the user goes online and creates a payment order. This order goes to other people that pays it and register the payment on the system. The system keeps track of all the payments, keeping the account balance up-to-date. The system needs a login system, bank integration, and to support at some point thousands of clients. We can find articles on the web about the benefits of using wordpress platform to build webapps. However, I could not find discussion with counterarguments to user wordpress. As the platform the most important choice in webapp project, I would to know more about the pitfalls and harms for choosing wordpress. The question is: What are the benefits and harms for choosing wordpress as a development platform for a webapp that need to be integrated with other system (backend systems) and to handle thousands of users (does it scale up?)?

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• pl/sql object types "ORA-06530: Reference to uninitialized composite" error

  - by mutoss

  hi, i have a type as follows: CREATE OR REPLACE TYPE tbusiness_inter_item_bag AS OBJECT ( item_id NUMBER, system_event_cd VARCHAR2 (20), CONSTRUCTOR FUNCTION tbusiness_inter_item_bag RETURN SELF AS RESULT ); CREATE OR REPLACE TYPE BODY tbusiness_inter_item_bag AS CONSTRUCTOR FUNCTION tbusiness_inter_item_bag RETURN SELF AS RESULT AS BEGIN RETURN; END; END; when i execute the following script, i got a "Reference to uninitialized composite" error, which is imho quite suitable. DECLARE item tbusiness_inter_item_bag; BEGIN item.system_event_cd := 'ABC'; END; This also raises the same error: item.item_id := 3; But if i change my object type into: CREATE OR REPLACE TYPE tbusiness_inter_item_bag AS OBJECT ( item_id NUMBER(1), system_event_cd VARCHAR2 (20), CONSTRUCTOR FUNCTION tbusiness_inter_item_bag RETURN SELF AS RESULT ); then the last statement raises no more error (where my "item" is still uninitialized): item.item_id := 3; Shouldn't i get the same ORA-06530 error? ps: Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bi

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• Java: how does isDirectory and isFile work in File-class?

  - by HH

  $ javac GetAllDirs.java GetAllDirs.java:16: cannot find symbol symbol : variable checkFile location: class GetAllDirs System.out.println(checkFile.getName()); ^ 1 error $ cat GetAllDirs.java import java.util.*; import java.io.*; public class GetAllDirs { public void getAllDirs(File file) { if(file.isDirectory()){ System.out.println(file.getName()); File checkFile = new File(file.getCanonicalPath()); }else if(file.isFile()){ System.out.println(file.getName()); File checkFile = new File(file.getParent()); }else{ // checkFile should get Initialized at least HERE! File checkFile = file; } System.out.println(file.getName()); // WHY ERROR HERE: checkfile not found System.out.println(checkFile.getName()); } public static void main(String[] args) { GetAllDirs dirs = new GetAllDirs(); File current = new File("."); dirs.getAllDirs(current); } }

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• Developing Mobile Applications: Web, Native, or Hybrid?

  - by Michelle Kimihira

  Authors: Joe Huang, Senior Principal Product Manager, Oracle Mobile Application Development Framework  and Carlos Chang, Senior Principal Product Director The proliferation of mobile devices and platforms represents a game-changing technology shift on a number of levels. Companies must decide not only the best strategic use of mobile platforms, but also how to most efficiently implement them. Inevitably, this conversation devolves to the developers, who face the task of developing and supporting mobile applications—not a simple task in light of the number of devices and platforms. Essentially, developers can choose from the following three different application approaches, each with its own set of pros and cons. Native Applications: This refers to apps built for and installed on a specific platform, such as iOS or Android, using a platform-specific software development kit (SDK).  For example, apps for Apple’s iPhone and iPad are designed to run specifically on iOS and are written in Xcode/Objective-C. Android has its own variation of Java, Windows uses C#, and so on.  Native apps written for one platform cannot be deployed on another. Native apps offer fast performance and access to native-device services but require additional resources to develop and maintain each platform, which can be expensive and time consuming. Mobile Web Applications: Unlike native apps, mobile web apps are not installed on the device; rather, they are accessed via a Web browser.  These are server-side applications that render HTML, typically adjusting the design depending on the type of device making the request.  There are no program coding constraints for writing server-side apps—they can be written in Java, C, PHP, etc., it doesn’t matter.  Instead, the server detects what type of mobile browser is pinging the server and adjusts accordingly. For example, it can deliver fully JavaScript and CSS-enabled content to smartphone browsers, while downgrading gracefully to basic HTML for feature phone browsers. Mobile apps work across platforms, but are limited to what you can do through a browser and require Internet connectivity. For certain types of applications, these constraints may not be an issue. Oracle supports mobile web applications via ADF Faces (for tablets) and ADF Mobile browser (Trinidad) for smartphone and feature phones. Hybrid Applications: As the name implies, hybrid apps combine technologies from native and mobile Web apps to gain the benefits each. For example, these apps are installed on a device, like their pure native app counterparts, while the user interface (UI) is based on HTML5.  This UI runs locally within the native container, which usually leverages the device’s browser engine.  The advantage of using HTML5 is a consistent, cross-platform UI that works well on most devices.  Combining this with the native container, which is installed on-device, provides mobile users with access to local device services, such as camera, GPS, and local device storage.  Native apps may offer greater flexibility in integrating with device native services.  However, since hybrid applications already provide device integrations that typical enterprise applications need, this is typically less of an issue.  The new Oracle ADF Mobile release is an HTML5 and Java hybrid framework that targets mobile app development to iOS and Android from one code base. So, Which is the Best Approach? The short answer is – the best choice depends on the type of application you are developing.  For instance, animation-intensive apps such as games would favor native apps, while hybrid applications may be better suited for enterprise mobile apps because they provide multi-platform support. Just for starters, the following issues must be considered when choosing a development path. Application Complexity: How complex is the application? A quick app that accesses a database or Web service for some data to display?  You can keep it simple, and a mobile Web app may suffice. However, for a mobile/field worker type of applications that supports mission critical functionality, hybrid or native applications are typically needed. Richness of User Interactivity: What type of user experience is required for the application?  Mobile browser-based app that’s optimized for mobile UI may suffice for quick lookup or productivity type of applications.  However, hybrid/native application would typically be required to deliver highly interactive user experiences needed for field-worker type of applications.  For example, interactive BI charts/graphs, maps, voice/email integration, etc.  In the most extreme case like gaming applications, native applications may be necessary to deliver the highly animated and graphically intensive user experience. Performance: What type of performance is required by the application functionality?  For instance, for real-time look up of data over the network, mobile app performance depends on network latency and server infrastructure capabilities.  If consistent performance is required, data would typically need to be cached, which is supported on hybrid or native applications only. Connectivity and Availability: What sort of connectivity will your application require? Does the app require Web access all the time in order to always retrieve the latest data from the server? Or do the requirements dictate offline support? While native and hybrid apps can be built to operate offline, Web mobile apps require Web connectivity. Multi-platform Requirements: The terms “consumerization of IT” and BYOD (bring your own device) effectively mean that the line between the consumer and the enterprise devices have become blurred. Employees are bringing their personal mobile devices to work and are often expecting that they work in the corporate network and access back-office applications.  Even if companies restrict access to the big dogs: (iPad, iPhone, Android phones and tablets, possibly Windows Phone and tablets), trying to support each platform natively will require increasing resources and domain expertise with each new language/platform. And let’s not forget the maintenance costs, involved in upgrading new versions of each platform.   Where multi-platform support is needed, Web mobile or hybrid apps probably have the advantage. Going native, and trying to support multiple operating systems may be cost prohibitive with existing resources and developer skills. Device-Services Access:  If your app needs to access local device services, such as the camera, contacts app, accelerometer, etc., then your choices are limited to native or hybrid applications.   Fragmentation: Apple controls Apple iOS and the only concern is what version iOS is running on any given device.   Not so Android, which is open source. There are many, many versions and variants of Android running on different devices, which can be a nightmare for app developers trying to support different devices running different flavors of Android.  (Is it an Amazon Kindle Fire? a Samsung Galaxy?  A Barnes & Noble Nook?) This is a nightmare scenario for native apps—on the other hand, a mobile Web or hybrid app, when properly designed, can shield you from these complexities because they are based on common frameworks.  Resources: How many developers can you dedicate to building and supporting mobile application development?  What are their existing skills sets?  If you’re considering native application development due to the complexity of the application under development, factor the costs of becoming proficient on a each platform’s OS and programming language. Add another platform, and that’s another language, another SDK. On the other side of the equation, Web mobile or hybrid applications are simpler to make, and readily support more platforms, but there may be performance trade-offs. Conclusion This only scratches the surface. However, I hope to have suggested some food for thought in choosing your mobile development strategy.  Do your due diligence, search the Web, read up on mobile, talk to peers, attend events. The development team at Oracle is working hard on mobile technologies to help customers extend enterprise applications to mobile faster and effectively.  To learn more on what Oracle has to offer, check out the Oracle ADF Mobile (hybrid) and ADF Faces/ADF Mobile browser (Web Mobile) solutions from Oracle.   Additional Information Blog: ADF Blog Product Information on OTN: ADF Mobile Product Information on Oracle.com: Oracle Fusion Middleware Follow us on Twitter and Facebook Subscribe to our regular Fusion Middleware Newsletter

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• Using rvm with a standalone ruby script

  - by John Yeates

  I have rvm installed on a Mac OS X 10.6 system with the system ruby and 1.9.1. I also have this basic ruby script: #!/usr/bin/ruby require 'curb-fu' I need the script to use the system ruby regardless of what rvm's using at any given time; I'm assuming that I've got that right, at least. I've switched to the system ruby (rvm use system) and then installed the gem (gem install curb-fu). If I run irb and type require 'curb-fu', it works. However, running that script with ./myscript.rb fails: /Users/me/bin/podcast_notify.rb:6:in `require': no such file to load -- curb-fu (LoadError) from /Users/me/bin/podcast_notify.rb:6 What's going wrong here? How do I install curb-fu so that it's always available to this script?

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• SICP making change

  - by RyanD

  So; I'm a hobbiest who's trying to work through SICP (it's free!) and there is an example procedure in the first chapter that is meant to count the possible ways to make change with american coins; (change-maker 100) = 292. It's implemented something like: (define (change-maker amount) (define (coin-value n) (cond ((= n 1) 1) ((= n 2) 5) ((= n 3) 10) ((= n 4) 25) ((= n 5) 50))) (define (iter amount coin-type) (cond ((= amount 0) 1) ((or (= coin-type 0) (< amount 0)) 0) (else (+ (iter amount (- coin-type 1)) (iter (- amount (coin-value coin-type)) coin-type))))) (iter amount 5)) Anyway; this is a tree-recursive procedure, and the author "leaves as a challenge" finding an iterative procedure to solve the same problem (ie fixed space). I have not had luck figuring this out or finding an answer after getting frustrated. I'm wondering if it's a brain fart on my part, or if the author's screwing with me.

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