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• invalid context 0x0 under iOS 7.0 and system degradation

  - by Alex

  I've read as many search results I could find on this dreaded problem, unfortunatelly, each one seems to focus on a specific function call. My problem is that I get the same error from multiple functions, which I am guessing are being called back from functions that I use. To make matters worse, the actual code is within a custom private framework which is being imported in another project, and as such, debugging isn't as simple? Can anyone point me to the right direction? I have a feeling I'm calling certain methods wrongly or with bad context, but the output from xcode is not very helpful at this point. : CGContextSetFillColorWithColor: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update. : CGContextSetStrokeColorWithColor: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update. CGContextSaveGState: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update. : CGContextSetFlatness: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update. : CGContextAddPath: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update. : CGContextDrawPath: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update. : CGContextRestoreGState: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update. : CGContextGetBlendMode: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update. Those errors may occur when a custom view is presented, or one of its inherited classes. At which point they spawn multiple times, until the keyboard won't provide any input. Touch events are still registered, but system slows down, and eventually may lead to unallocated object errors.

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• FaceBook Login Problem

  - by toman

  Hi All, I am for an application which extracts information from facebook search, hence i require to login facebook. i have registered my application in facebook developers site and have got api key and secret key. in my code i am getting an exception when i am trying to login. Here is my code for login to facebook: import com.facebook.api.FacebookRestClient; import org.apache.commons.httpclient.HttpClient; import org.apache.commons.httpclient.HttpState; import org.apache.commons.httpclient.NameValuePair; import org.apache.commons.httpclient.methods.GetMethod; import org.apache.commons.httpclient.methods.PostMethod; import org.apache.commons.httpclient.params.HttpClientParams; public class FaceLogin { public FaceLogin(){ getUserID("username", "password"); } private static void getUserID(String email, String password) { String session = null; try { HttpClient http = new HttpClient(); http.setParams(new HttpClientParams()); //http.getHostConfiguration().setHost("http://www.facebook.com/"); http.setState(new HttpState()); String api_key = "****some key****"; String secret = "****some key****"; FacebookRestClient client = new FacebookRestClient(api_key, secret); client.setIsDesktop(true); String token = client.auth_createToken(); final String loginId = "http://www.facebook.com/login.php"; GetMethod get = new GetMethod(loginId + "?api_key=" + api_key + "&v=1.0&auth_token=" +token); System.out.println("Get="+get); http.executeMethod(get); PostMethod post = new PostMethod(loginId); post.addParameter(new NameValuePair("api_key", api_key)); post.addParameter(new NameValuePair("v", "1.0")); post.addParameter(new NameValuePair("auth_token", token)); post.addParameter(new NameValuePair("fbconnect","true")); post.addParameter(new NameValuePair("return_session","true")); post.addParameter(new NameValuePair("session_key_only","true")); post.addParameter(new NameValuePair("req_perms","read_stream,publish_stream")); post.addParameter(new NameValuePair("lsd","8HYdi")); post.addParameter(new NameValuePair("locale","en_US")); post.addParameter(new NameValuePair("persistent","1")); post.addParameter(new NameValuePair("email", email)); post.addParameter(new NameValuePair("pass", password)); System.out.println("Token ="+token); int postStatus = http.executeMethod(post); System.out.println("Response : " + postStatus); session = client.auth_getSession(token); // Here I am getting error System.out.println("Session string: " + session); long userid = client.users_getLoggedInUser(); System.out.println("User Id is : " + userid); } catch (Exception e) { e.printStackTrace(); } } public static void main(String k[]) { FaceLogin facebookLoginObj=new FaceLogin(); } } I am getting the following exception: org.apache.commons.httpclient.HttpMethodBase processResponseHeaders WARNING: Cookie rejected: "$Version=0; $Domain=deleted; $Path=/; $Domain=.facebook.com". Cookie name may not start with $ Response : 200 Jun 8, 2010 2:07:36 PM org.apache.commons.httpclient.HttpMethodBase processResponseHeaders WARNING: Cookie rejected: "$Version=0; $Path=deleted; $Path=/; $Domain=.facebook.com". Cookie name may not start with $ Facebook returns error code 100 com.facebook.api.FacebookException: Invalid parameter - v - 1.0 at com.facebook.api.FacebookRestClient.callMethod(FacebookRestClient.java:828) - auth_token - 004e90dc8818d5f0921d1065d24508d3 at com.facebook.api.FacebookRestClient.callMethod(FacebookRestClient.java:606) - method - facebook.auth.getSession - call_id - 1275986256796 - api_key - f7cb1e48c383ef599da9021fc4dec322 at com.facebook.api.FacebookRestClient.auth_getSession(FacebookRestClient.java:1891) at facebookcrawler.FacebookLogin.getUserID(FacebookLogin.java:81) at facebookcrawler.FacebookLogin.( - sig - 9344ec75b74a0a87bcae645046d45da8 FacebookLogin.java:24) at facebookcrawler.FaceLogin.main(FaceLogin.java:80) Here may be the problem is for creating session, i searched for all the solutions on net but could not helped me to get login. Please help me if you can suggest me some way to resolve this problem. i thanks to all your valuable suggestion.

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• .NET Declarative Security: Why is SecurityAction.Deny impossible to work with?

  - by rally25rs

  I've been messing with this for about a day and a half now sifting through .NET reflector and MSDN docs, and can't figure anything out... As it stands in the .NET framework, you can demand that the current Principal belong to a role to be able to execute a method by marking a method like this: [PrincipalPermission(SecurityAction.Demand, Role = "CanEdit")] public void Save() { ... } I am working with an existing security model that already has a "ReadOnly" role defined, so I need to do exactly the opposite of above... block the Save() method if a user is in the "ReadOnly" role. No problem, right? just flip the SecurityAction to .Deny: [PrincipalPermission(SecurityAction.Deny, Role = "ReadOnly")] public void Save() { ... } Well, it turns out that this does nothing at all. The method still runs fine. It seems that the PrincipalPermissionAttribute defines: public override IPermission CreatePermission() But when the attribute is set to SecurityAction.Deny, this method is never called, so no IPermission object is ever created. Does anyone know of a way to get .Deny to work? I've been trying to make a custom secutiry attribute, but even that doesn't work. I tried to get tricky and do: public class MyPermissionAttribute : CodeAccessSecurityAttribute { private SecurityAction securityAction; public MyPermissionAttribute(SecurityAction action) : base(SecurityAction.Demand) { if (action != SecurityAction.Demand && action != SecurityAction.Deny) throw new ArgumentException("Unsupported SecurityAction. Only Demand and Deny are supported."); this.securityAction = action; } public override IPermission CreatePermission() { // do something based on the SecurityAction... } } Notice my attribute constructor always passes SecurityAction.Demand, which is the one action that would work previously. However, even in this case, the CreatePermission() method is still only called when the attribute is set to .Demand, and not .Deny! Maybe the runtime is actually checking the attribute instead of the SecurityAction passed to the CodeAccessSecurityAttribute constructor? I'm not sure what else to try here... anyone have any ideas? You wouldn't think it would be that hard to deny method access based on a role, instead of only demanding it. It really disturbed me that the default PrincipalPermission appears from within an IDE like it would be just fine doing a .Deny, and there is like a 1-liner in the MSDN docs that hint that it won't work. You would think the PrincipalPermissionAttribute constructor would throw an exception immediately if anything other that .Demand is specified, since that could create a big security hole! I never would have realized that .Deny does nothing at all if I hadn't been unit testing! Again, all this stems from having to deal with an existing security model that has a "ReadOnly" role that needs to be denied access, instead of doing it the other way around, where I cna just grant access to a role. Thanks for any help! Quick followup: I can actually make my custom attribute work by doing this: public class MyPermissionAttribute : CodeAccessSecurityAttribute { public SecurityAction SecurityAction { get; set; } public MyPermissionAttribute(SecurityAction action) : base(action) { } public override IPermission CreatePermission() { switch(this.SecurityAction) { ... } // check Demand or Deny } } And decorating the method: [MyPermission(SecurityAction.Demand, SecurityAction = SecurityAction.Deny, Role = "ReadOnly")] public void Save() { ... } But that is terribly ugly, since I'm specifying both Demand and Deny in the same attribute. But it does work... Another interesting note: My custom class extends CodeAccessSecurityAttribute, which in turn only extends SecurityAttribute. If I cnage my custom class to directly extend SecurityAttribute, then nothing at all works. So it seems the runtime is definately looking for only CodeAccessSecurityAttribute instances in the metadata, and does something funny with the SecurityAction specified, even if a custom constructor overrides it.

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• OSGI Declarative Services (DS): What is a good way of using service component instances

  - by Christoph

  I am just getting started with OSGI and Declarative Services (DS) using Equinox and Eclipse PDE. I have 2 Bundles, A and B. Bundle A exposes a component which is consumed by Bundle B. Both bundles also expose this service to the OSGI Service registry again. Everything works fine so far and Equinox is wireing the components together, which means the Bundle A and Bundle B are instanciated by Equinox (by calling the default constructor) and then the wireing happens using the bind / unbind methods. Now, as Equinox is creating the instances of those components / services I would like to know what is the best way of getting this instance? So assume there is third class class which is NOT instantiated by OSGI: Class WantsToUseComponentB{ public void doSomethingWithComponentB(){ // how do I get componentB??? Something like this maybe? ComponentB component = (ComponentB)someComponentRegistry.getComponent(ComponentB.class.getName()); } I see the following options right now: 1. Use a ServiceTracker in the Activator to get the Service of ComponentBundleA.class.getName() (I have tried that already and it works, but it seems to much overhead to me) and make it available via a static factory methods public class Activator{ private static ServiceTracker componentBServiceTracker; public void start(BundleContext context){ componentBServiceTracker = new ServiceTracker(context, ComponentB.class.getName(),null); } public static ComponentB getComponentB(){ return (ComponentB)componentBServiceTracker.getService(); }; } 2. Create some kind of Registry where each component registers as soon as the activate() method is called. public ComponentB{ public void bind(ComponentA componentA){ someRegistry.registerComponent(this); } or public ComponentB{ public void activate(ComponentContext context){ someRegistry.registerComponent(this); } } } 3. Use an existing registry inside osgi / equinox which has those instances? I mean OSGI is already creating instances and wires them together, so it has the objects already somewhere. But where? How can I get them? Conclusion Where does the class WantsToUseComponentB (which is NOT a Component and NOT instantiated by OSGI) get an instance of ComponentB from? Are there any patterns or best practises? As I said I managed to use a ServiceTracker in the Activator, but I thought that would be possible without it. What I am looking for is actually something like the BeanContainer of Springframework, where I can just say something like Container.getBean(ComponentA.BEAN_NAME). But I don't want to use Spring DS. I hope that was clear enough. Otherwise I can also post some source code to explain in more detail. Thanks Christoph UPDATED: Answer to Neil's comment: Thanks for clarifying this question against the original version, but I think you still need to state why the third class cannot be created via something like DS. Hmm don't know. Maybe there is a way but I would need to refactor my whole framework to be based on DS, so that there are no "new MyThirdClass(arg1, arg2)" statements anymore. Don't really know how to do that, but I read something about ComponentFactories in DS. So instead of doing a MyThirdClass object = new MyThirdClass(arg1, arg2); I might do a ComponentFactory myThirdClassFactory = myThirdClassServiceTracker.getService(); // returns a if (myThirdClassFactory != null){ MyThirdClass object = objectFactory.newInstance(); object.setArg1("arg1"); object.setArg2("arg2"); } else{ // here I can assume that some service of ComponentA or B went away so MyThirdClass Componenent cannot be created as there are missing dependencies? } At the time of writing I don't know exactly how to use the ComponentFactories but this is supposed to be some kind of pseudo code :) Thanks Christoph

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• Is it bad practice to apply class-based design to JavaScript programs?

  - by helixed

  JavaScript is a prototyped-based language, and yet it has the ability to mimic some of the features of class-based object-oriented languages. For example, JavaScript does not have a concept of public and private members, but through the magic of closures, it's still possible to provide the same functionality. Similarly, method overloading, interfaces, namespaces and abstract classes can all be added in one way or another. Lately, as I've been programming in JavaScript, I've felt like I'm trying to turn it into a class-based language instead of using it in the way it's meant to be used. It seems like I'm trying to force the language to conform to what I'm used to. The following is some JavaScript code I've written recently. It's purpose is to abstract away some of the effort involved in drawing to the HTML5 canvas element. /* Defines the Drawing namespace. */ var Drawing = {}; /* Abstract base which represents an element to be drawn on the screen. @param The graphical context in which this Node is drawn. @param position The position of the center of this Node. */ Drawing.Node = function(context, position) { return { /* The method which performs the actual drawing code for this Node. This method must be overridden in any subclasses of Node. */ draw: function() { throw Exception.MethodNotOverridden; }, /* Returns the graphical context for this Node. @return The graphical context for this Node. */ getContext: function() { return context; }, /* Returns the position of this Node. @return The position of this Node. */ getPosition: function() { return position; }, /* Sets the position of this Node. @param thePosition The position of this Node. */ setPosition: function(thePosition) { position = thePosition; } }; } /* Define the shape namespace. */ var Shape = {}; /* A circle shape implementation of Drawing.Node. @param context The graphical context in which this Circle is drawn. @param position The center of this Circle. @param radius The radius of this circle. @praram color The color of this circle. */ Shape.Circle = function(context, position, radius, color) { //check the parameters if (radius < 0) throw Exception.InvalidArgument; var node = Drawing.Node(context, position); //overload the node drawing method node.draw = function() { var context = this.getContext(); var position = this.getPosition(); context.fillStyle = color; context.beginPath(); context.arc(position.x, position.y, radius, 0, Math.PI*2, true); context.closePath(); context.fill(); } /* Returns the radius of this Circle. @return The radius of this Circle. */ node.getRadius = function() { return radius; }; /* Sets the radius of this Circle. @param theRadius The new radius of this circle. */ node.setRadius = function(theRadius) { radius = theRadius; }; /* Returns the color of this Circle. @return The color of this Circle. */ node.getColor = function() { return color; }; /* Sets the color of this Circle. @param theColor The new color of this Circle. */ node.setColor = function(theColor) { color = theColor; }; //return the node return node; }; The code works exactly like it should for a user of Shape.Circle, but it feels like it's held together with Duct Tape. Can somebody provide some insight on this?

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• NullPointerException in ItemizedOverlay.getIndexToDraw

  - by lyricsboy

  I have a relatively simple MapActivity that I'm trying to make display a list of "camps" within a given map region. I've created a custom subclass of OverlayItem called CampOverlayItem, a custom ItemizedOverlay called CampsOverlay that returns CampOverlayItems, and of course a MapActivity subclass that populates the map. I'm pulling the overlay data from a database using an AsyncTask as created in my activity. The AsyncTask is triggered from a ViewTreeObserver.OnGlobalLayoutListener attached to the MapView. In the onPostExecute method of the AsyncTask, I create a new instance of my CampsOverlay class and pass it a list of the camps returned from the database (which are fetched in doInBackground). I then call: mapView.getOverlays().add(newOverlay); where newOverlay is the CampsOverlay I just created. All of this code runs without error, but when the Map tries to draw itself, I get a NullPointerException with the following stack trace: java.lang.NullPointerException at com.google.android.maps.ItemizedOverlay.getIndexToDraw(ItemizedOverlay.java: 211) at com.google.android.maps.ItemizedOverlay.draw(ItemizedOverlay.java:240) at com.google.android.maps.Overlay.draw(Overlay.java:179) at com.google.android.maps.OverlayBundle.draw(OverlayBundle.java: 42) at com.google.android.maps.MapView.onDraw(MapView.java:476) at android.view.View.draw(View.java:6274) at android.view.ViewGroup.drawChild(ViewGroup.java:1526) at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1256) at android.view.ViewGroup.drawChild(ViewGroup.java:1524) at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1256) at android.view.View.draw(View.java:6277) at android.widget.FrameLayout.draw(FrameLayout.java:352) at android.view.ViewGroup.drawChild(ViewGroup.java:1526) at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1256) at android.view.ViewGroup.drawChild(ViewGroup.java:1524) at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1256) at android.view.ViewGroup.drawChild(ViewGroup.java:1524) at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1256) at android.view.ViewGroup.drawChild(ViewGroup.java:1524) at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1256) at android.view.ViewGroup.drawChild(ViewGroup.java:1524) at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1256) at android.view.View.draw(View.java:6277) at android.widget.FrameLayout.draw(FrameLayout.java:352) at android.view.ViewGroup.drawChild(ViewGroup.java:1526) at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1256) at android.view.View.draw(View.java:6277) at android.widget.FrameLayout.draw(FrameLayout.java:352) at com.android.internal.policy.impl.PhoneWindow $DecorView.draw(PhoneWindow.java:1883) at android.view.ViewRoot.draw(ViewRoot.java:1332) at android.view.ViewRoot.performTraversals(ViewRoot.java:1097) at android.view.ViewRoot.handleMessage(ViewRoot.java:1613) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:123) at android.app.ActivityThread.main(ActivityThread.java:4203) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:521) at com.android.internal.os.ZygoteInit $MethodAndArgsCaller.run(ZygoteInit.java:791) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:549) at dalvik.system.NativeStart.main(Native Method) Because it seems particularly relevant, here is the code for my ItemizedOverlay subclass: public class CampsOverlay extends ItemizedOverlay<CampOverlayItem> { private ArrayList<Camp> camps = null; public CampsOverlay(Drawable defaultMarker, ArrayList<Camp> theCamps) { super(defaultMarker); this.camps = theCamps; } @Override protected CampOverlayItem createItem(int i) { Camp camp = camps.get(i); CampOverlayItem item = new CampOverlayItem(camp); return item; } @Override protected boolean onTap(int index) { // TODO Auto-generated method stub return super.onTap(index); } @Override public int size() { return camps.size(); } } Does anyone have any idea what could be happening here? I've attempted to verify that everything I have control over is non-null. I can provide more code if necessary.

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• How to immediate send mail without prompt confirmation dialog

  - by lmengyew

  I'm using Delphi XE3 and below is my sample application: unit Unit1; interface uses Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics, Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls; type TForm1 = class(TForm) Button1: TButton; procedure Button1Click(Sender: TObject); private function Send(const FromAddr, ToAddr, Subject: String; const AttachFiles: array of string; const MsgBody: String): boolean; end; var Form1: TForm1; implementation uses Winapi.Mapi; {$R *.dfm} procedure TForm1.Button1Click(Sender: TObject); begin Send('', '[email protected]', 'test', [], ''); end; function TForm1.Send(const FromAddr, ToAddr, Subject: String; const AttachFiles: array of string; const MsgBody: String): boolean; var Msg: TMapiMessage; lpSender, lpRecipient: TMapiRecipDesc; Attach: array of TMapiFileDesc; SMTP: TFNMapiSendMail; MAPIModule: HModule; i: integer; S: string; begin Result := False; FillChar(Msg, SizeOf(Msg), 0); Msg.lpszSubject := PAnsiChar(UTF8String(Subject)); Msg.lpszNoteText := PAnsiChar(UTF8String(MsgBody)); if FromAddr <> '' then begin lpSender.ulRecipClass := MAPI_ORIG; lpSender.lpszName := PAnsiChar(UTF8String(FromAddr)); lpSender.lpszAddress := PAnsiChar(UTF8String(FromAddr)); lpSender.ulReserved := 0; lpSender.ulEIDSize := 0; lpSender.lpEntryID := Nil; Msg.lpOriginator := @lpSender; end; if ToAddr <> '' then begin lpRecipient.ulRecipClass := MAPI_TO; lpRecipient.lpszName := PAnsiChar(UTF8String(ToAddr)); lpRecipient.lpszAddress := PAnsiChar(UTF8String(ToAddr)); lpRecipient.ulReserved := 0; lpRecipient.ulEIDSize := 0; lpRecipient.lpEntryID := Nil; Msg.nRecipCount := 1; Msg.lpRecips := @lpRecipient; end; SetLength(Attach, Length(AttachFiles)); FillChar(Attach[0], Length(Attach) * SizeOf(TMapiFileDesc), 0); i := 0; for S in AttachFiles do begin Attach[i].nPosition := Cardinal($FFFFFFFF); Attach[i].lpszPathName := PAnsiChar(UTF8String(S)); Inc(i); end; Msg.nFileCount := Length(AttachFiles); if Msg.nFileCount = 0 then Msg.lpFiles := nil else Msg.lpFiles := @Attach[0]; MAPIModule := LoadLibrary(PChar(MAPIDLL)); if MAPIModule <> 0 then begin try @SMTP := GetProcAddress(MAPIModule, 'MAPISendMail'); if @SMTP <> nil then Result := SMTP(0, Application.Handle, Msg, 0, 0) = SUCCESS_SUCCESS; finally FreeLibrary(MAPIModule); end; end; end; end. When i click the Button1, it will prompt the confirmation dialog as print screen. My question is how to immediate send mail without prompt the confirmation dialog? Is this possible to achieve?

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• My google map android app keeps crashing

  - by Manny264

  I have followed about two tutorials from vogella and some other tutorial that looked similar...very similar but to no avail. I load the app on my nexus 7 and it just crashes "Unfortunately MyMapView has stopped working" on launch.This is the manifest: ` <uses-sdk android:minSdkVersion="17" android:targetSdkVersion="17" /> <uses-feature android:glEsVersion="0x00020000" android:required="true"/> <uses-permission android:name="android.permission.INTERNET" /> <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" /> <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" /> <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" /> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/> <uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES"/> <application android:allowBackup="true" android:icon="@drawable/ic_launcher" android:label="@string/app_name" android:theme="@style/AppTheme" > <uses-library android:name="com.google.android.maps" /> <activity android:name="com.macmozart.mymapview.MainActivity" android:label="@string/app_name" > <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> <meta-data android:name="com.google.android.maps.v2.API_KEY" android:value="AIzaSyBZ1Bt7rjB863Jy-B05zls6k8XZsBGQ6-4" /> </application> ` Followed by my main layout: <fragment android:id="@+id/map" android:layout_width="match_parent" android:layout_height="match_parent" class="com.google.android.gms.maps.MapFragment" /> and finally my java class: package com.macmozart.mymapview; import android.app.Activity; import android.os.Bundle; import com.google.android.gms.maps.CameraUpdateFactory; import com.google.android.gms.maps.GoogleMap; import com.google.android.gms.maps.MapFragment; import com.google.android.gms.maps.model.BitmapDescriptorFactory; import com.google.android.gms.maps.model.LatLng; import com.google.android.gms.maps.model.Marker; import com.google.android.gms.maps.model.MarkerOptions; import com.google.android.maps.*; public class MainActivity extends Activity { static final LatLng HAMBURG = new LatLng(53.558, 9.927); static final LatLng KIEL = new LatLng(53.551, 9.993); private GoogleMap map; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); map = ((MapFragment) getFragmentManager().findFragmentById(R.id.map)) .getMap(); if (map != null) { Marker hamburg = map.addMarker(new MarkerOptions() .position(HAMBURG).title("Hamburg")); Marker kiel = map.addMarker(new MarkerOptions() .position(KIEL) .title("Kiel") .snippet("Kiel is cool") .icon(BitmapDescriptorFactory .fromResource(R.drawable.ic_launcher))); map.moveCamera(CameraUpdateFactory.newLatLngZoom(HAMBURG, 15)); // Zoom in, animating the camera. map.animateCamera(CameraUpdateFactory.zoomTo(10), 2000, null); } } } Any idea what im doing wrong I really need this to work

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• ASP.NET MVC 2 "value" in IsValid override in DataAnnotation attribute passed is null, when incorrect

  - by goldenelf2

  Hello to all! This is my first question here on stack overflow. i need help on a problem i encountered during an ASP.NET MVC2 project i am currently working on. I should note that I'm relatively new to MVC design, so pls bear my ignorance. Here goes : I have a regular form on which various details about a person are shown. One of them is "Date of Birth". My view is like this <div class="form-items"> <%: Html.Label("DateOfBirth", "Date of Birth:") %> <%: Html.EditorFor(m => m.DateOfBirth) %> <%: Html.ValidationMessageFor(m => m.DateOfBirth) %> </div> I'm using an editor template i found, to show only the date correctly : <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<System.DateTime?>"%> <%= Html.TextBox("", (Model.HasValue ? Model.Value.ToShortDateString() : string.Empty))%> I used LinqToSql designer to create my model from an sql database. In order to do some validation i made a partial class Person to extend the one created by the designer (under the same namespace) : [MetadataType(typeof(IPerson))] public partial class Person : IPerson { //To create buddy class } public interface IPerson { [Required(ErrorMessage="Please enter a name")] string Name { get; set; } [Required(ErrorMessage="Please enter a surname")] string Surname { get; set; } [Birthday] DateTime? DateOfBirth { get; set; } [Email(ErrorMessage="Please enter a valid email")] string Email { get; set; } } I want to make sure that a correct date is entered. So i created a custom DataAnnotation attribute in order to validate the date : public class BirthdayAttribute : ValidationAttribute { private const string _errorMessage = "Please enter a valid date"; public BirthdayAttribute() : base(_errorMessage) { } public override bool IsValid(object value) { if (value == null) { return true; } DateTime temp; bool result = DateTime.TryParse(value.ToString(), out temp); return result; } } Well, my problem is this. Once i enter an incorrect date in the DateOfBirth field then no custom message is displayed even if use the attribute like [Birthday(ErrorMessage=".....")]. The message displayed is the one returned from the db ie "The value '32/4/1967' is not valid for DateOfBirth.". I tried to enter some break points around the code, and found out that the "value" in attribute is always null when the date is incorrect, but always gets a value if the date is in correct format. The same ( value == null) is passed also in the code generated by the designer. This thing is driving me nuts. Please can anyone help me deal with this? Also if someone can tell me where exactly is the point of entry from the view to the database. Is it related to the model binder? because i wanted to check exactly what value is passed once i press the "submit" button. Thank you.

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• JAVA BubbleSort Output Plotting

  - by John Smith

  I'm not sure how to plot the output I get with my run time results for BubbleSort. Here's the thing: I've written a working BubbleSort algorithm that does exactly as it should. But I wish to plot the output, to show the following: Best Case, Worst Case, Average Case ... How would I go about plotting it on a graph? Here is the code: public class BubbleSort { static double bestTime = 10000000, worstTime = 0; public static void main(String[] args) { int BubArray[] = new int[]{13981, 6793, 2662, 10986, 733, ... #1000 integers}; System.out.println("Unsorted List Before Bubble Sort"); for(int a = 0; a < BubArray.length; a++){ System.out.print(BubArray[a] + " "); } System.out.println("\n Bubble Sort Execution ..."); for(int i=0; i<10000;i++) { bubbleSortTimeTaken(BubArray, i); } int itrs = bubbleSort(BubArray); System.out.println(""); System.out.println("Array After Bubble Sort"); System.out.println("Moves Taken for Sort : " + itrs + " Moves."); System.out.println("BestTime: " + bestTime + " WorstTime: " + worstTime); System.out.print("Sorted Array: \n"); for(int a = 0; a < BubArray.length; a++){ System.out.print(BubArray[a] + " "); } } private static int bubbleSort(int[] BubArray) { int z = BubArray.length; int temp = 0; int itrs = 0; for(int a = 0; a < z; a++){ for(int x=1; x < (z-a); x++){ if(BubArray[x-1] > BubArray[x]){ temp = BubArray[x-1]; BubArray[x-1] = BubArray[x]; BubArray[x] = temp; } itrs++; } } return itrs; } public static void bubbleSortTimeTaken(int[] BubArray, int n) { long startTime = System.nanoTime(); bubbleSort(BubArray); double timeTaken = (System.nanoTime() - startTime)/1000000d; if (timeTaken > 0) { worstTime = timeTaken; } else if (timeTaken < bestTime) { bestTime = timeTaken; } System.out.println(n + "," + timeTaken); } } The output are as the following ( execution number, time (nano/10^6): Unsorted List Before Bubble Sort 13981 6793 2662 .... #1000 integers Bubble Sort Execution ... 0, 18.319891 1, 4.728978 2, 3.670697 3, 3.648922 4, 4.161576 5, 3.824369 .... 9995, 4.331423 9996, 3.692473 9997, 3.709893 9998, 6.16055 9999, 4.32209 Array After Bubble Sort Moves Taken for Sort : 541320 Moves. BestTime: 1.0E7 WorstTime: 4.32209 Sorted Array: 10 11 17 24 57 60 83 128 141 145 ... #1000 integers I am looking for graphs to represent Average, Best and Worst case based on the output but my current graphs don't look correct. Any help would be appreciated, thanks.

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• How to determine if two generic type values are equal?

  - by comecme

  I'm trying to figure out how I can successfully determine if two generic type values are equal to each other. Based on Mark Byers' answer on this question I would think I can just use value.Equals() where value is a generic type. My actual problem is in a LinkedList implementation, but the problem can be shown with this simpler example. class GenericOjbect<T> { public T Value { get; private set; } public GenericOjbect(T value) { Value = value; } public bool Equals(T value) { return (Value.Equals(value)); } } Now I define an instance of GenericObject<StringBuilder> containing new StringBuilder("StackOverflow"). I would expect to get true if I call Equals(new StringBuilder("StackOverflow") on this GenericObject instance, but I get false. A sample program showing this: using System; using System.Text; class Program { static void Main() { var sb1 = new StringBuilder("StackOverflow"); var sb2 = new StringBuilder("StackOverflow"); Console.WriteLine("StringBuilder compare"); Console.WriteLine("1. == " + (sb1 == sb2)); Console.WriteLine("2. Object.Equals " + (Object.Equals(sb1, sb2))); Console.WriteLine("3. this.Equals " + (sb1.Equals(sb2))); var go1 = new GenericOjbect<StringBuilder>(sb1); var go2 = new GenericOjbect<StringBuilder>(sb2); Console.WriteLine("\nGenericObject compare"); Console.WriteLine("1. == " + (go1 == go2)); Console.WriteLine("2. Object.Equals " + (Object.Equals(go1, go2))); Console.WriteLine("3. this.Equals " + (go1.Equals(go2))); Console.WriteLine("4. Value.Equals " + (go1.Value.Equals(go2.Value))); } } For the three methods of comparing two StringBuilder objects, only the StringBuilder.Equals instance method (the third line) returns true. This is what I expected. But when comparing the GenericObject objects, its Equals() method (the third line) returns false. Interestingly enough, the fourth compare method does return true. I'd think the third and fourth comparison are actually doing the same thing. I would have expected true. Because in the Equals() method of the GenericObject class, both value and Value are of type T which in this case is a StringBuilder. Based on Mark Byers' answer in this question, I would've expected the Value.Equals() method to be using the StringBuilder's Equals() method. And as I've shown, the StringBuilder's Equal() method does return true. I've even tried public bool Equals(T value) { return EqualityComparer<T>.Default.Equals(Value, value); } but that also returns false. So, two questions here: Why doesn't the code return true? How could I implement the Equals method so it does return true?

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• boost::serialization with mutable members

  - by redmoskito

  Using boost::serialization, what's the "best" way to serialize an object that contains cached, derived values in mutable members, such that cached members aren't serialized, but on deserialization, they are initialized the their appropriate default. A definition of "best" follows later, but first an example: class Example { public: Example(float n) : num(n), sqrt_num(-1.0) {} float get_num() const { return num; } // compute and cache sqrt on first read float get_sqrt() const { if(sqrt_num < 0) sqrt_num = sqrt(num); return sqrt_num; } template <class Archive> void serialize(Archive& ar, unsigned int version) { ... } private: float num; mutable float sqrt_num; }; On serialization, only the "num" member should be saved. On deserialization, the sqrt_num member must be initialized to its sentinel value indicating it needs to be computed. What is the most elegant way to implement this? In my mind, an elegant solution would avoid splitting serialize() into separate save() and load() methods (which introduces maintenance problems). One possible implementation of serialize: template <class Archive> void serialize(Archive& ar, unsigned int version) { ar & num; sqrt_num = -1.0; } This handles the deserialization case, but in the serialization case, the cached value is killed and must be recomputed. Also, I've never seen an example of boost::serialize that explicitly sets members inside of serialize(), so I wonder if this is generally not recommended. Some might suggest that the default constructor handles this, for example: int main() { Example e; { std::ifstream ifs("filename"); boost::archive::text_iarchive ia(ifs); ia >> e; } cout << e.get_sqrt() << endl; return 0; } which works in this case, but I think fails if the object receiving the deserialized data has already been initialized, as in the example below: int main() { Example ex1(4); Example ex2(9); cout << ex1.get_sqrt() << endl; // outputs 2; cout << ex2.get_sqrt() << endl; // outputs 3; // the following two blocks should implement ex2 = ex1; // save ex1 to archive { std::ofstream ofs("filename"); boost::archive::text_oarchive oa(ofs); oa << ex1; } // read it back into ex2 { std::ifstream ifs("filename"); boost::archive::text_iarchive ia(ifs); ia >> ex2; } // these should be equal now, but aren't, // since Example::serialize() doesn't modify num_sqrt cout << ex1.get_sqrt() << endl; // outputs 2; cout << ex2.get_sqrt() << endl; // outputs 3; return 0; } I'm sure this issue has come up with others, but I have struggled to find any documentation on this particular scenario. Thanks!

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• How to make exported .XLS file Editable

  - by nCdy

  How to make exported .XLS file Editable Thid code makes .XLS File Read Only :( using System; using System.Data; using System.Configuration; using System.IO; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; public class GridViewExportUtil { /// <param name="fileName"></param> /// <param name="gv"></param> public static void Export(string fileName, GridView gv) { HttpContext.Current.Response.Clear(); HttpContext.Current.Response.AddHeader( "content-disposition", string.Format("content-disposition", "attachment; filename={0}", fileName)); HttpContext.Current.Response.ContentType = "application/ms-excel"; HttpContext.Current.Response.Cache.SetCacheability(HttpCacheability.NoCache); HttpContext.Current.Response.Charset = System.Text.Encoding.Unicode.EncodingName; HttpContext.Current.Response.ContentEncoding = System.Text.Encoding.Unicode; HttpContext.Current.Response.BinaryWrite(System.Text.Encoding.Unicode.GetPreamble()); using (StringWriter sw = new StringWriter()) { using (HtmlTextWriter htw = new HtmlTextWriter(sw)) { // Create a form to contain the grid Table table = new Table(); // add the header row to the table if (gv.HeaderRow != null) { GridViewExportUtil.PrepareControlForExport(gv.HeaderRow); table.Rows.Add(gv.HeaderRow); } // add each of the data rows to the table foreach (GridViewRow row in gv.Rows) { GridViewExportUtil.PrepareControlForExport(row); table.Rows.Add(row); } // add the footer row to the table if (gv.FooterRow != null) { GridViewExportUtil.PrepareControlForExport(gv.FooterRow); table.Rows.Add(gv.FooterRow); } // render the table into the htmlwriter table.RenderControl(htw); // render the htmlwriter into the response HttpContext.Current.Response.Write(sw.ToString()); HttpContext.Current.Response.End(); } } } /// <summary> /// Replace any of the contained controls with literals /// </summary> /// <param name="control"></param> private static void PrepareControlForExport(Control control) { for (int i = 0; i < control.Controls.Count; i++) { Control current = control.Controls[i]; if (current is LinkButton) { control.Controls.Remove(current); control.Controls.AddAt(i, new LiteralControl((current as LinkButton).Text)); } else if (current is ImageButton) { control.Controls.Remove(current); control.Controls.AddAt(i, new LiteralControl((current as ImageButton).AlternateText)); } else if (current is HyperLink) { control.Controls.Remove(current); control.Controls.AddAt(i, new LiteralControl((current as HyperLink).Text)); } else if (current is DropDownList) { control.Controls.Remove(current); control.Controls.AddAt(i, new LiteralControl((current as DropDownList).SelectedItem.Text)); } else if (current is CheckBox) { control.Controls.Remove(current); control.Controls.AddAt(i, new LiteralControl((current as CheckBox).Checked ? "True" : "False")); } if (current.HasControls()) { GridViewExportUtil.PrepareControlForExport(current); } } } }

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• Mercurial "hg clone" on Windows via ssh with plink issue

  - by Kyle Tolle

  I have a Windows Server 2008 machine (iis7) that has CopSSH set up on it. To connect to it, I have a Windows 7 machine with Mercurial 1.5.1 (and TortoiseHg) installed. I can connect to the server using PuTTY with a non-standard ssh port and a .ppk file just fine. So I know the server can be SSH'd into. Next, I wanted to use the CLI to connect via hg clone to get a private repo. I've seen elsewhere that you need to have ssh configured in your mercurial.ini file, so my mercurial.ini has a line: ssh = plink.exe -ssh -C -l username -P #### -i "C:/Program Files/PuTTY/Key Files/KyleKey.ppk" Note: username is filled in with the username I set up via copSSH. #### is filled in with the non-standard ssh port I've defined for copSSH. I try to do the command hg clone ssh://inthom.com but I get this error: remote: bash: inthom.com: command not found abort: no suitable response from remote hg! It looks like hg or plink parses the hostname such that it thinks that inthom.com is a command instead of the server to ssh to. That's really odd. Next, I tried to just use plink to connect by plink -P #### ssh://inthom.com, and I am then prompted for my username, and next password. I enter them both and then I get this error: bash: ssh://inthom.com: No such file or directory So now it looks like plink doesn't parse the hostname correctly. I fiddled around for a while trying to figure out how to do call hg clone with an empty ssh:// field and eventually figured out that this command allows me to reach the server and clone a test repo on the inthom.com server: hg clone ssh://!/Repos/test ! is the character I've found that let's me leave the hostname blank, but specify the repo folder to clone. What I really don't understand is how plink knows what server to ssh to at all. neither my mercurial.ini nor the command specify a server. None of the hg clone examples I've seen have a ! character. They all use an address, which makes sense, so you can connect to any repo via ssh that you want to clone. My only guess is that it somehow defaults to the last server I used PuTTY to SSH to, but I SSH'd into another server, and then tried to use plink to get to it, but plink still defaults to inthom.com (verified with the -v arg to plink). So I am at a loss as to how plink gets this server value at all. For "fun", I tried using TortoiseHg and can only clone a repo when I use ssh://!/Repos/test as the Source. Now, you can see that, since plink doesn't parse the hostname correctly, I had to specify the port number and username in the mercurial.ini file, instead of in the hostname like [email protected]:#### like you'd expect to. Trying to figure this out at first drove me insane, because I would get errors that the host couldn't be reached, which I knew shouldn't be the case. My question is how can I configure my setup so that ssh://[email protected]:####/Repos/test is parsed correctly as the username, hostname, port number, and repo to copy? Is it something wrong with the version of plink that I'm using, or is there some setting I may have messed up? If it is plink's fault, is there an alternative tool I can use? I'm going to try to get my friend set up to connect to this same repo, so I'd like to have a clean solution instead of this ! business. Especially when I have no idea how plink gets this default server, so I'm not sure if he'd even be able to get to inthom.com correctly. PS. I've had to use a ton of different tutorials to even get to this stage. Therefore, I haven't tried pushing any changes to the server yet. Hopefully I'll get this figured out and then I can try pushing changes to the repo.

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• Error Handling without Exceptions

  - by James

  While searching SO for approaches to error handling related to business rule validation , all I encounter are examples of structured exception handling. MSDN and many other reputable development resources are very clear that exceptions are not to be used to handle routine error cases. They are only to be used for exceptional circumstances and unexpected errors that may occur from improper use by the programmer (but not the user.) In many cases, user errors such as fields that are left blank are common, and things which our program should expect, and therefore are not exceptional and not candidates for use of exceptions. QUOTE: Remember that the use of the term exception in programming has to do with the thinking that an exception should represent an exceptional condition. Exceptional conditions, by their very nature, do not normally occur; so your code should not throw exceptions as part of its everyday operations. Do not throw exceptions to signal commonly occurring events. Consider using alternate methods to communicate to a caller the occurrence of those events and leave the exception throwing for when something truly out of the ordinary happens. For example, proper use: private void DoSomething(string requiredParameter) { if (requiredParameter == null) throw new ArgumentExpcetion("requiredParameter cannot be null"); // Remainder of method body... } Improper use: // Renames item to a name supplied by the user. Name must begin with an "F". public void RenameItem(string newName) { // Items must have names that begin with "F" if (!newName.StartsWith("F")) throw new RenameException("New name must begin with /"F/""); // Remainder of method body... } In the above case, according to best practices, it would have been better to pass the error up to the UI without involving/requiring .NET's exception handling mechanisms. Using the same example above, suppose one were to need to enforce a set of naming rules against items. What approach would be best? Having the method return a enumerated result? RenameResult.Success, RenameResult.TooShort, RenameResult.TooLong, RenameResult.InvalidCharacters, etc. Using an event in a controller class to report to the UI class? The UI calls the controller's RenameItem method, and then handles an AfterRename event that the controller raises and that has rename status as part of the event args? The controlling class directly references and calls a method from the UI class that handles the error, e.g. ReportError(string text). Something else... ? Essentially, I want to know how to perform complex validation in classes that may not be the Form class itself, and pass the errors back to the Form class for display -- but I do not want to involve exception handling where it should not be used (even though it seems much easier!) Based on responses to the question, I feel that I'll have to state the problem in terms that are more concrete: UI = User Interface, BLL = Business Logic Layer (in this case, just a different class) User enters value within UI. UI reports value to BLL. BLL performs routine validation of the value. BLL discovers rule violation. BLL returns rule violation to UI. UI recieves return from BLL and reports error to user. Since it is routine for a user to enter invalid values, exceptions should not be used. What is the right way to do this without exceptions?

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• CryptoExcercise Encryption/Decryption Problem

  - by venkat

  I am using apples "cryptoexcercise" (Security.Framework) in my application to encrypt and decrypt a data of numeric value. When I give the input 950,128 the values got encrypted, but it is not getting decrypted and exists with the encrypted value only. This happens only with the mentioned numeric values. Could you please check this issue and give the solution to solve this problem? here is my code (void)testAsymmetricEncryptionAndDecryption { uint8_t *plainBuffer; uint8_t *cipherBuffer; uint8_t *decryptedBuffer; const char inputString[] = "950"; int len = strlen(inputString); if (len > BUFFER_SIZE) len = BUFFER_SIZE-1; plainBuffer = (uint8_t *)calloc(BUFFER_SIZE, sizeof(uint8_t)); cipherBuffer = (uint8_t *)calloc(CIPHER_BUFFER_SIZE, sizeof(uint8_t)); decryptedBuffer = (uint8_t *)calloc(BUFFER_SIZE, sizeof(uint8_t)); strncpy( (char *)plainBuffer, inputString, len); NSLog(@"plain text : %s", plainBuffer); [self encryptWithPublicKey:(UInt8 *)plainBuffer cipherBuffer:cipherBuffer]; NSLog(@"encrypted data: %s", cipherBuffer); [self decryptWithPrivateKey:cipherBuffer plainBuffer:decryptedBuffer]; NSLog(@"decrypted data: %s", decryptedBuffer); free(plainBuffer); free(cipherBuffer); free(decryptedBuffer); } (void)encryptWithPublicKey:(uint8_t *)plainBuffer cipherBuffer:(uint8_t *)cipherBuffer { OSStatus status = noErr; size_t plainBufferSize = strlen((char *)plainBuffer); size_t cipherBufferSize = CIPHER_BUFFER_SIZE; NSLog(@"SecKeyGetBlockSize() public = %d", SecKeyGetBlockSize([self getPublicKeyRef])); // Error handling // Encrypt using the public. status = SecKeyEncrypt([self getPublicKeyRef], PADDING, plainBuffer, plainBufferSize, &cipherBuffer[0], &cipherBufferSize ); NSLog(@"encryption result code: %d (size: %d)", status, cipherBufferSize); NSLog(@"encrypted text: %s", cipherBuffer); } (void)decryptWithPrivateKey:(uint8_t *)cipherBuffer plainBuffer:(uint8_t *)plainBuffer { OSStatus status = noErr; size_t cipherBufferSize = strlen((char *)cipherBuffer); NSLog(@"decryptWithPrivateKey: length of buffer: %d", BUFFER_SIZE); NSLog(@"decryptWithPrivateKey: length of input: %d", cipherBufferSize); // DECRYPTION size_t plainBufferSize = BUFFER_SIZE; // Error handling status = SecKeyDecrypt([self getPrivateKeyRef], PADDING, &cipherBuffer[0], cipherBufferSize, &plainBuffer[0], &plainBufferSize ); NSLog(@"decryption result code: %d (size: %d)", status, plainBufferSize); NSLog(@"FINAL decrypted text: %s", plainBuffer); } (SecKeyRef)getPublicKeyRef { OSStatus sanityCheck = noErr; SecKeyRef publicKeyReference = NULL; if (publicKeyRef == NULL) { NSMutableDictionary *queryPublicKey = [[NSMutableDictionary alloc] init]; // Set the public key query dictionary. [queryPublicKey setObject:(id)kSecClassKey forKey:(id)kSecClass]; [queryPublicKey setObject:publicTag forKey:(id)kSecAttrApplicationTag]; [queryPublicKey setObject:(id)kSecAttrKeyTypeRSA forKey:(id)kSecAttrKeyType]; [queryPublicKey setObject:[NSNumber numberWithBool:YES] forKey:(id)kSecReturnRef]; // Get the key. sanityCheck = SecItemCopyMatching((CFDictionaryRef)queryPublicKey, (CFTypeRef *)&publicKeyReference); if (sanityCheck != noErr) { publicKeyReference = NULL; } [queryPublicKey release]; } else { publicKeyReference = publicKeyRef; } return publicKeyReference; } (SecKeyRef)getPrivateKeyRef { OSStatus resultCode = noErr; SecKeyRef privateKeyReference = NULL; if(privateKeyRef == NULL) { NSMutableDictionary * queryPrivateKey = [[NSMutableDictionary alloc] init]; // Set the private key query dictionary. [queryPrivateKey setObject:(id)kSecClassKey forKey:(id)kSecClass]; [queryPrivateKey setObject:privateTag forKey:(id)kSecAttrApplicationTag]; [queryPrivateKey setObject:(id)kSecAttrKeyTypeRSA forKey:(id)kSecAttrKeyType]; [queryPrivateKey setObject:[NSNumber numberWithBool:YES] forKey:(id)kSecReturnRef]; // Get the key. resultCode = SecItemCopyMatching((CFDictionaryRef)queryPrivateKey, (CFTypeRef *)&privateKeyReference); NSLog(@"getPrivateKey: result code: %d", resultCode); if(resultCode != noErr) { privateKeyReference = NULL; } [queryPrivateKey release]; } else { privateKeyReference = privateKeyRef; } return privateKeyReference; }

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• Const references when dereferencing iterator on set, starting from Visual Studio 2010

  - by Patrick

  Starting from Visual Studio 2010, iterating over a set seems to return an iterator that dereferences the data as 'const data' instead of non-const. The following code is an example of something that does compile on Visual Studio 2005, but not on 2010 (this is an artificial example, but clearly illustrates the problem we found on our own code). In this example, I have a class that stores a position together with a temperature. I define comparison operators (not all them, just enough to illustrate the problem) that only use the position, not the temperature. The point is that for me two instances are identical if the position is identical; I don't care about the temperature. #include <set> class DataPoint { public: DataPoint (int x, int y) : m_x(x), m_y(y), m_temperature(0) {} void setTemperature(double t) {m_temperature = t;} bool operator<(const DataPoint& rhs) const { if (m_x==rhs.m_x) return m_y<rhs.m_y; else return m_x<rhs.m_x; } bool operator==(const DataPoint& rhs) const { if (m_x!=rhs.m_x) return false; if (m_y!=rhs.m_y) return false; return true; } private: int m_x; int m_y; double m_temperature; }; typedef std::set<DataPoint> DataPointCollection; void main(void) { DataPointCollection points; points.insert (DataPoint(1,1)); points.insert (DataPoint(1,1)); points.insert (DataPoint(1,2)); points.insert (DataPoint(1,3)); points.insert (DataPoint(1,1)); for (DataPointCollection::iterator it=points.begin();it!=points.end();++it) { DataPoint &point = *it; point.setTemperature(10); } } In the main routine I have a set to which I add some points. To check the correctness of the comparison operator, I add data points with the same position multiple times. When writing the contents of the set, I can clearly see there are only 3 points in the set. The for-loop loops over the set, and sets the temperature. Logically this is allowed, since the temperature is not used in the comparison operators. This code compiles correctly in Visual Studio 2005, but gives compilation errors in Visual Studio 2010 on the following line (in the for-loop): DataPoint &point = *it; The error given is that it can't assign a "const DataPoint" to a [non-const] "DataPoint &". It seems that you have no decent (= non-dirty) way of writing this code in VS2010 if you have a comparison operator that only compares parts of the data members. Possible solutions are: Adding a const-cast to the line where it gives an error Making temperature mutable and making setTemperature a const method But to me both solutions seem rather 'dirty'. It looks like the C++ standards committee overlooked this situation. Or not? What are clean solutions to solve this problem? Did some of you encounter this same problem and how did you solve it? Patrick

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• Show MapView on PopupWindow

  - by Ali Nadi

  I want to show MapView on PopupWindow and get error when press-on Map. Please help! Liste.java MapView mapView; View view; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.liste); LayoutInflater mInflater = (LayoutInflater) this.getSystemService(Context.LAYOUT_INFLATER_SERVICE); view = mInflater.inflate(R.layout.pop_up, (ViewGroup) findViewById(R.id.popup_element), false); mapView = (MapView) view.findViewById(R.id.mapview_popup); listView.setOnItemClickListener(new OnItemClickListener() { @Override public void onItemClick(AdapterView<?> arg0, View v, int position, long id) { initiatePopupWindow(earthQuakeList.get(position)); } }); } private void initiatePopupWindow(EqData data) { try { mapView.setBuiltInZoomControls(true); List<Overlay> mapOverlays = mapView.getOverlays(); Drawable marker = this.getResources().getDrawable(R.drawable.marker1); HaritaOverlay itemizedoverlay = new HaritaOverlay(marker, this); Coordination coord = data.getCoordination(); GeoPoint point = new GeoPoint( (int)coord.latitude, (int)coord.longitude); OverlayItem overlayitem = new OverlayItem(point, data.lokasyon, data.name); itemizedoverlay.addOverlay(overlayitem); mapOverlays.add(itemizedoverlay); Display display = getWindowManager().getDefaultDisplay(); pw = new PopupWindow(view, display.getWidth(), display.getHeight()/2, true); // display the popup in the center pw.showAtLocation(view, Gravity.CENTER, 0, display.getHeight()/2); } catch (Exception e) { e.printStackTrace(); } } pop_up.xml <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:baselineAligned="false" android:orientation="vertical" android:weightSum="540" android:id="@+id/popup_element" > ... <LinearLayout android:layout_width="fill_parent" android:layout_height="0dip" android:layout_weight="440" > <com.google.android.maps.MapView android:id="@+id/mapview_popup" android:layout_width="fill_parent" android:layout_height="fill_parent" android:apiKey="@string/ApiMapKey" android:clickable="true" /> </LinearLayout> Error 07-23 17:36:28.820: E/MapActivity(12413): Couldn't get connection factory client 07-23 17:36:37.760: E/AndroidRuntime(12413): FATAL EXCEPTION: main 07-23 17:36:37.760: E/AndroidRuntime(12413): android.view.WindowManager$BadTokenException: Unable to add window -- token android.view.ViewRoot$W@40590b70 is not valid; is your activity running? 07-23 17:36:37.760: E/AndroidRuntime(12413): at android.view.ViewRoot.setView(ViewRoot.java:528) 07-23 17:36:37.760: E/AndroidRuntime(12413): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:177) 07-23 17:36:37.760: E/AndroidRuntime(12413): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91) 07-23 17:36:37.760: E/AndroidRuntime(12413): at android.view.Window$LocalWindowManager.addView(Window.java:465) 07-23 17:36:37.760: E/AndroidRuntime(12413): at android.widget.ZoomButtonsController.setVisible(ZoomButtonsController.java:370) 07-23 17:36:37.760: E/AndroidRuntime(12413): at com.google.android.maps.MapView.displayZoomControls(MapView.java:1053) 07-23 17:36:37.760: E/AndroidRuntime(12413): at com.google.android.maps.MapView$1.onDown(MapView.java:341) 07-23 17:36:37.760: E/AndroidRuntime(12413): at com.google.android.maps.GestureDetector.onTouchEvent(GestureDetector.java:488) 07-23 17:36:37.760: E/AndroidRuntime(12413): at com.google.android.maps.MapView.onTouchEvent(MapView.java:683) 07-23 17:36:37.760: E/AndroidRuntime(12413): at android.view.View.dispatchTouchEvent(View.java:3901) 07-23 17:36:37.760: E/AndroidRuntime(12413): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:903) 07-23 17:36:37.760: E/AndroidRuntime(12413): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:869) 07-23 17:36:37.760: E/AndroidRuntime(12413): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:869) 07-23 17:36:37.760: E/AndroidRuntime(12413): at android.view.ViewRoot.deliverPointerEvent(ViewRoot.java:2200) 07-23 17:36:37.760: E/AndroidRuntime(12413): at android.view.ViewRoot.handleMessage(ViewRoot.java:1884) 07-23 17:36:37.760: E/AndroidRuntime(12413): at android.os.Handler.dispatchMessage(Handler.java:99) 07-23 17:36:37.760: E/AndroidRuntime(12413): at android.os.Looper.loop(Looper.java:130) 07-23 17:36:37.760: E/AndroidRuntime(12413): at android.app.ActivityThread.main(ActivityThread.java:3835) 07-23 17:36:37.760: E/AndroidRuntime(12413): at java.lang.reflect.Method.invokeNative(Native Method) 07-23 17:36:37.760: E/AndroidRuntime(12413): at java.lang.reflect.Method.invoke(Method.java:507) 07-23 17:36:37.760: E/AndroidRuntime(12413): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:847) 07-23 17:36:37.760: E/AndroidRuntime(12413): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:605) 07-23 17:36:37.760: E/AndroidRuntime(12413): at dalvik.system.NativeStart.main(Native Method)

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• Win32: IProgressDialog will not disappear until you mouse over it.

  - by Ian Boyd

  i'm using the Win32 progress dialog. The damnest thing is that when i call: progressDialog.StopProgressDialog(); it doesn't disappear. It stays on screen until the user moves her mouse over it - then it suddenly disappers. The call to StopProgressDialog returns right away (i.e. it's not a synchronous call). i can prove this by doing things after the call has returned: private void button1_Click(object sender, EventArgs e) { //Force red background to prove we've started this.BackColor = Color.Red; this.Refresh(); //Start a progress dialog IProgressDialog pd = (IProgressDialog)new ProgressDialog(); pd.StartProgressDialog(this.Handle, null, PROGDLG.Normal, IntPtr.Zero); //The long running operation System.Threading.Thread.Sleep(10000); //Stop the progress dialog pd.SetLine(1, "Stopping Progress Dialog", false, IntPtr.Zero); pd.StopProgressDialog(); pd = null; //Return form to normal color to prove we've stopped. this.BackColor = SystemColors.Control; this.Refresh(); } The form: starts gray turns red to show we've stared turns back to gray color to show we've called stop So the call to StopProgressDialog has returned, except the progress dialog is still sitting there, mocking me, showing the message: Stopping Progress Dialog Doesn't Appear for 10 seconds Additionally, the progress dialog does not appear on screen until the System.Threading.Thread.Sleep(10000); ten second sleep is over. Not limited to .NET WinForms The same code also fails in Delphi, which is also an object wrapper around Window's windows: procedure TForm1.Button1Click(Sender: TObject); var pd: IProgressDialog; begin Self.Color := clRed; Self.Repaint; pd := CoProgressDialog.Create; pd.StartProgressDialog(Self.Handle, nil, PROGDLG_NORMAL, nil); Sleep(10000); pd.SetLine(1, StringToOleStr('Stopping Progress Dialog'), False, nil); pd.StopProgressDialog; pd := nil; Self.Color := clBtnFace; Self.Repaint; end; PreserveSig An exception would be thrown if StopProgressDialog was failing. Most of the methods in IProgressDialog, when translated into C# (or into Delphi), use the compiler's automatic mechanism of converting failed COM HRESULTS into a native language exception. In other words the following two signatures will throw an exception if the COM call returned an error HRESULT (i.e. a value less than zero): //C# void StopProgressDialog(); //Delphi procedure StopProgressDialog; safecall; Whereas the following lets you see the HRESULT's and react yourself: //C# [PreserveSig] int StopProgressDialog(); //Delphi function StopProgressDialog: HRESULT; stdcall; HRESULT is a 32-bit value. If the high-bit is set (or the value is negative) it is an error. i am using the former syntax. So if StopProgressDialog is returning an error it will be automatically converted to a language exception. Note: Just for SaG i used the [PreserveSig] syntax, the returned HRESULT is zero; MsgWait? The symptom is similar to what Raymond Chen described once, which has to do with the incorrect use of PeekMessage followed by MsgWaitForMultipleObjects: "Sometimes my program gets stuck and reports one fewer record than it should. I have to jiggle the mouse to get the value to update. After a while longer, it falls two behind, then three..." But that would mean that the failure is in IProgressDialog, since it fails equally well on CLR .NET WinForms and native Win32 code.

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• Spring Custom Filter Problem?

  - by mr.lost

  greetings all,iam using spring security 3 and i want to perform some logic(saving some data in the session) when the user is visiting the site and he's remembered so i extended the GenericFilterBean class and performed the logic in the doFilter method then complete the filter chain by calling the chain.doFilter method,and then inserted that filter after the remember me filter in the security.xml file? but there's a problem is the filter is executed on each page even if the user is remembered or not is there's something wrong with the filter implementation or the position of the filter? and i have a simple question,is the filter chain by default is executed on each page? and when making a custom filter should i add it to the web.xml too? the filter class: package projects.internal; import java.io.IOException; import javax.servlet.FilterChain; import javax.servlet.ServletException; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.security.core.Authentication; import org.springframework.security.core.context.SecurityContextHolder; import org.springframework.web.filter.GenericFilterBean; import projects.ProjectManager; public class rememberMeFilter extends GenericFilterBean { private ProjectManager projectManager; @Autowired public rememberMeFilter(ProjectManager projectManager) { this.projectManager = projectManager; } @Override public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException { System.out.println("In The Filter"); Authentication auth = (Authentication) SecurityContextHolder .getContext().getAuthentication(); HttpServletResponse response = ((HttpServletResponse) res); HttpServletRequest request = ((HttpServletRequest) req); // if the user is not remembered,do nothing if (auth == null) { chain.doFilter(request, response); } else { // the user is remembered save some data in the session System.out.println("User Is Remembered"); chain.doFilter(request, response); } } } the security.xml file: <beans:beans xmlns="http://www.springframework.org/schema/security" xmlns:beans="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/security http://www.springframework.org/schema/security/spring-security-3.0.xsd"> <global-method-security pre-post-annotations="enabled"> </global-method-security> <http use-expressions="true" > <remember-me data-source-ref="dataSource"/> <intercept-url pattern="/" access="permitAll" /> <intercept-url pattern="/images/**" filters="none" /> <intercept-url pattern="/scripts/**" filters="none" /> <intercept-url pattern="/styles/**" filters="none" /> <intercept-url pattern="/p/login" filters="none" /> <intercept-url pattern="/p/register" filters="none" /> <intercept-url pattern="/p/forgot_password" filters="none" /> <intercept-url pattern="/p/**" access="isAuthenticated()" /> <custom-filter after="REMEMBER_ME_FILTER" ref="rememberMeFilter" /> <form-login login-processing-url="/j_spring_security_check" login-page="/p/login" authentication-failure-url="/p/login?login_error=1" default-target-url="/p/dashboard" authentication-success-handler-ref="myAuthenticationHandler" always-use-default-target="false" /> <logout/> </http> <beans:bean id="myAuthenticationHandler" class="projects.internal.myAuthenticationHandler" /> <beans:bean id="rememberMeFilter" class="projects.internal.rememberMeFilter" > </beans:bean> <authentication-manager alias="authenticationManager"> <authentication-provider> <password-encoder hash="md5" /> <jdbc-user-service data-source-ref="dataSource" /> </authentication-provider> </authentication-manager> </beans:beans> any help?

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• Creating my own Stack

  - by Malaken

  I am creating my own stack for my data structures class. For our assignment we are using the assignment to convert a real-time infix equation into a postfix equation. I thought my program: took input determines if it was digit or number(operand) prints it out determines if input is operator (+,-,/,*) adds to stack or prints out, depending on stack precedence Instead it prints out the operands as expect, but I get this error when I enter an operator .../dorun.sh line 33: 4136 Segmentation fault sh "$" [code] #include using namespace std; class DishWell{ public: char ReturnEnd(){ return Well.back(); } void Push(char x){ Well.push_back(x); } void Pop(){ Well.pop_back(); } bool IsEmpty(){ return Well.empty(); } private: vector<char> Well; }; #include <iostream> bool Precidence(char Input, char Stack){ int InputPrecidence,StackPrecidence; switch (Input){ case '*': InputPrecidence = 4; break; case '/': InputPrecidence = 4; break; case '+': InputPrecidence = 3; break; case '-': InputPrecidence = 3; break; case '(': InputPrecidence = 2; break; default: InputPrecidence = 0; } switch (Stack){ case '*': StackPrecidence = 4; break; case '/': StackPrecidence = 4; break; case '+': StackPrecidence = 3; break; case '-': StackPrecidence = 3; break; case '(': StackPrecidence = 2; break; default: StackPrecidence = 0; } if(InputPrecidence>StackPrecidence) return true; else return false; } int main(int argc, char** argv) { DishWell DishTray; char Input; bool InputFlag; InputFlag = true; while(InputFlag){ cin>>Input; if((((Input>='a'&&Input<='z')||(Input>='A'&&Input<='Z'))|| (Input>='0'&&Input<='9')))//If Digit or Number cout<<Input; if((Input=='*'||Input=='/'||Input=='+'||Input=='-')){//if operand if(Precidence(Input,DishTray.ReturnEnd())) DishTray.Push(Input); else if(!Precidence(Input,DishTray.ReturnEnd())) cout<<Input; } else if(!((((Input>='a'&&Input<='z')||(Input>='A'&&Input<='Z'))|| (Input>='0'&&Input<='9')))||((Input=='*'||Input=='/'||Input=='+'||Input=='-')))//if not digit/numer or operand InputFlag = false; } while(!DishTray.IsEmpty()){ cout<<DishTray.ReturnEnd(); DishTray.Pop(); } return 0; [code] My code is very length, I know, but I appreciate help. Especially any times for efficency or future coding. Thanks again P.S. Dr. Zemoudeh, this is your student Macaire

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• How to read URDU from url and show it to your mobile using java Me

  - by Basit

  HI, Hope you all will be fine. Actually I m facing a problem. Actually i am using Google translation API. What my application does it connect to CGI-script, i pass value to it using GET then the CGI script connect to Google API, Translate the mesage from english to Urdu and then i retreive it.Here is the code [Java] import java.io.*; import javax.microedition.io.*; import javax.microedition.lcdui.*; import javax.microedition.midlet.*; /** * An example MIDlet to invoke a CGI script (GET method). */ public class InvokeCgiMidlet1 extends MIDlet { private Display display; String url = "http://xxx.xxx.xx.xxx/cgi-bin/api/GT/GT_Send_Msg.cgi?message=my%20name%20is%20basit"; public InvokeCgiMidlet1() { display = Display.getDisplay(this); } /** * Initialization. Invoked when we activate the MIDlet. */ public void startApp() { try { getGrade(url); } catch (IOException e) { System.out.println("IOException " + e); e.printStackTrace(); } } /** * Pause, discontinue .... */ public void pauseApp() { } /** * Destroy must cleanup everything. */ public void destroyApp(boolean unconditional) { } /** * Retrieve a grade.... */ void getGrade(String url) throws IOException { HttpConnection c = null; InputStream is = null; OutputStream os = null; StringBuffer b = new StringBuffer(); TextBox t = null; String response; try { c = (HttpConnection)Connector.open(url, Connector.READ_WRITE); c.setRequestMethod(HttpConnection.GET); c.setRequestProperty("User-Agent","Profile/MIDP-1.0 Confirguration/CLDC-1.0"); c.setRequestProperty("Content-Type","application/x-www-form-urlencoded"); c.setRequestProperty("User-Agent","Profile/MIDP-2.0 Configuration/CLDC-1.1"); c.setRequestProperty("Accept-Charset","UTF-8;q=0.7,*;q=0.7"); c.setRequestProperty("Accept-Encoding","gzip, deflate"); c.setRequestProperty("Accept","text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5"); c.setRequestProperty("Content-Language", "en-EN"); os = c.openOutputStream(); Reader r = new InputStreamReader(c.openDataInputStream(), "UTF-8"); int ch; while ((ch = r.read()) != -1) { b.append((char) ch ); //System.out.println((char)ch + "->" + ch + "->" + ch); } t = new TextBox("Final Grades", b.reverse().toString(), 1024, 0); } finally { if(is!= null) { is.close(); } if(os != null) { os.close(); } if(c != null) { c.close(); } } display.setCurrent(t); } } [/Java] The problem is as i told you that the translated text is in Urdu. So when it appear on screen each character is separate like this. ? ?? ? ? ?? . Because i read character by character I want it to appear in proper form like this ??????? So how can i do this. Is there font rendering required. If yes then how can i do it or any other method please hep me. Thanks

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• Clickonce downloading the deploy files via HTTP and not HTTPS

  - by Scott Manning

  I am working on a project to deploy a project via clickonce. The website where these files are housed will only accept HTTPS traffic and if you attempt to connect via HTTP, our siteminder agent will redirect you to a HTTPS login form. We cannot disable the siteminder agent or enable HTTP for security reasons. In the application file, I have a codebase that references an absolute path to the manifest and it is via HTTPS <dependency> <dependentAssembly dependencyType="install" codebase="https://psaportal.ilab.test.com/testprinting/Application_Files/testprint_1_0_0_1/testprint.exe.manifest" size="10147"> <assemblyIdentity name="testprint.exe" version="1.0.0.1" publicKeyToken="9a078649ee05e0e7" language="neutral" processorArchitecture="msil" type="win32" /> <hash> <dsig:Transforms> <dsig:Transform Algorithm="urn:schemas-microsoft-com:HashTransforms.Identity" /> </dsig:Transforms> <dsig:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1" /> <dsig:DigestValue>2nch1T0SmlAycmePobtg9F1qF7c=</dsig:DigestValue> </hash> </dependentAssembly> </dependency> In running wireshark and decoding the SSL traffic (I am using the server’s private key in wireshark to decrypt the SSL traffic). I see the request to the application’s manifest file is via HTTPS (This is a good thing). But when the clickonce tries to download the testprint.exe.deploy and the other respective files, it is always via HTTP and the siteminder jumps in and redirects the requests which kills the clickonce install with errors. I have tried to specific an absolute codebase reference in the manifest file, but then I start getting entrypoint errors when the manifest is downloaded by the Clickonce installer. The current dependency section from the manifest file looks like the following: <dependency> <dependentAssembly dependencyType="install" allowDelayedBinding="true" codebase="testprint.exe" size="107008"> <assemblyIdentity name="testprint" version="1.0.0.1" language="neutral" processorArchitecture="msil" /> <hash> <dsig:Transforms> <dsig:Transform Algorithm="urn:schemas-microsoft-com:HashTransforms.Identity" /> </dsig:Transforms> <dsig:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1" /> <dsig:DigestValue>dm2nJsu/5UyaEXSDmnISwfnE9MM=</dsig:DigestValue> </hash> </dependentAssembly> </dependency> I have verified that the website where the application, manifest and deploy files are all under the same URL and the SSL certificate is a valid certificate. We have tried about every combination of generating application and manifest files as we a dream up and are looking for other solutions. The application is using .NET 3.5 and we have tried building the application and manifest files via VS2008, VS2010 and mage with no success. Does anyone know how to get all of the deploy files to always download via HTTPS?

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• Thread Synchronisation 101

  - by taspeotis

  Previously I've written some very simple multithreaded code, and I've always been aware that at any time there could be a context switch right in the middle of what I'm doing, so I've always guarded access the shared variables through a CCriticalSection class that enters the critical section on construction and leaves it on destruction. I know this is fairly aggressive and I enter and leave critical sections quite frequently and sometimes egregiously (e.g. at the start of a function when I could put the CCriticalSection inside a tighter code block) but my code doesn't crash and it runs fast enough. At work my multithreaded code needs to be a tighter, only locking/synchronising at the lowest level needed. At work I was trying to debug some multithreaded code, and I came across this: EnterCriticalSection(&m_Crit4); m_bSomeVariable = true; LeaveCriticalSection(&m_Crit4); Now, m_bSomeVariable is a Win32 BOOL (not volatile), which as far as I know is defined to be an int, and on x86 reading and writing these values is a single instruction, and since context switches occur on an instruction boundary then there's no need for synchronising this operation with a critical section. I did some more research online to see whether this operation did not need synchronisation, and I came up with two scenarios it did: The CPU implements out of order execution or the second thread is running on a different core and the updated value is not written into RAM for the other core to see; and The int is not 4-byte aligned. I believe number 1 can be solved using the "volatile" keyword. In VS2005 and later the C++ compiler surrounds access to this variable using memory barriers, ensuring that the variable is always completely written/read to the main system memory before using it. Number 2 I cannot verify, I don't know why the byte alignment would make a difference. I don't know the x86 instruction set, but does mov need to be given a 4-byte aligned address? If not do you need to use a combination of instructions? That would introduce the problem. So... QUESTION 1: Does using the "volatile" keyword (implicity using memory barriers and hinting to the compiler not to optimise this code) absolve a programmer from the need to synchronise a 4-byte/8-byte on x86/x64 variable between read/write operations? QUESTION 2: Is there the explicit requirement that the variable be 4-byte/8-byte aligned? I did some more digging into our code and the variables defined in the class: class CExample { private: CRITICAL_SECTION m_Crit1; // Protects variable a CRITICAL_SECTION m_Crit2; // Protects variable b CRITICAL_SECTION m_Crit3; // Protects variable c CRITICAL_SECTION m_Crit4; // Protects variable d // ... }; Now, to me this seems excessive. I thought critical sections synchronised threads between a process, so if you've got one you can enter it and no other thread in that process can execute. There is no need for a critical section for each variable you want to protect, if you're in a critical section then nothing else can interrupt you. I think the only thing that can change the variables from outside a critical section is if the process shares a memory page with another process (can you do that?) and the other process starts to change the values. Mutexes would also help here, named mutexes are shared across processes, or only processes of the same name? QUESTION 3: Is my analysis of critical sections correct, and should this code be rewritten to use mutexes? I have had a look at other synchronisation objects (semaphores and spinlocks), are they better suited here? QUESTION 4: Where are critical sections/mutexes/semaphores/spinlocks best suited? That is, which synchronisation problem should they be applied to. Is there a vast performance penalty for choosing one over the other? And while we're on it, I read that spinlocks should not be used in a single-core multithreaded environment, only a multi-core multithreaded environment. So, QUESTION 5: Is this wrong, or if not, why is it right? Thanks in advance for any responses :)

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• How to get an X11 Window from a Process ID ?

  - by Adam Pierce

  Under Linux, my C++ application is using fork() and execv() to launch multiple instances of OpenOffice so as to view some powerpoint slide shows. This part works. Next I want to be able to move the OpenOffice windows to specific locations on the display. I can do that with the XMoveResizeWindow() function but I need to find the Window for each instance. I have the process ID of each instance, how can I find the X11 Window from that ? UPDATE - Thanks to Andy's suggestion, I have pulled this off. I'm posting the code here to share it with the Stack Overflow community. Unfortunately Open Office does not seem to set the _NET_WM_PID property so this doesn't ultimately solve my problem but it does answer the question. // Attempt to identify a window by name or attribute. // by Adam Pierce <[email protected]> #include <X11/Xlib.h> #include <X11/Xatom.h> #include <iostream> #include <list> using namespace std; class WindowsMatchingPid { public: WindowsMatchingPid(Display *display, Window wRoot, unsigned long pid) : _display(display) , _pid(pid) { // Get the PID property atom. _atomPID = XInternAtom(display, "_NET_WM_PID", True); if(_atomPID == None) { cout << "No such atom" << endl; return; } search(wRoot); } const list<Window> &result() const { return _result; } private: unsigned long _pid; Atom _atomPID; Display *_display; list<Window> _result; void search(Window w) { // Get the PID for the current Window. Atom type; int format; unsigned long nItems; unsigned long bytesAfter; unsigned char *propPID = 0; if(Success == XGetWindowProperty(_display, w, _atomPID, 0, 1, False, XA_CARDINAL, &type, &format, &nItems, &bytesAfter, &propPID)) { if(propPID != 0) { // If the PID matches, add this window to the result set. if(_pid == *((unsigned long *)propPID)) _result.push_back(w); XFree(propPID); } } // Recurse into child windows. Window wRoot; Window wParent; Window *wChild; unsigned nChildren; if(0 != XQueryTree(_display, w, &wRoot, &wParent, &wChild, &nChildren)) { for(unsigned i = 0; i < nChildren; i++) search(wChild[i]); } } }; int main(int argc, char **argv) { if(argc < 2) return 1; int pid = atoi(argv[1]); cout << "Searching for windows associated with PID " << pid << endl; // Start with the root window. Display *display = XOpenDisplay(0); WindowsMatchingPid match(display, XDefaultRootWindow(display), pid); // Print the result. const list<Window> &result = match.result(); for(list<Window>::const_iterator it = result.begin(); it != result.end(); it++) cout << "Window #" << (unsigned long)(*it) << endl; return 0; }

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