class hierarchy - Page 744

Stagnating in programming

- by Coder

Time after time this question came up in my mind, but up until today I wasn't thinking about it much. I have been programming for maybe around 8 years now, and for the last two years it seems I'm not as keen to pick up new technologies anymore. Maybe that's a burnout or something, but I'd say it's experience and what I like, that's stopping me from running after the latest and greatest. I'm C++ developer, by this I mean, I love close to metal programming. I have no problems tracing problems through assembly, using tools like WinDbg or HexView. When I use constructs, I think about how they are realized underneath, how the bits are set and unset under the hood. I love battling with complex threading problems and doing everything hardcore way, even by hand if the regular solutions seem half baked. But I also love the C++0x stuff, and use it a lot. And all C++ code as long as it's not cumbersome compared to C counterparts, sometimes I also fall back to sort of "Super C" if the C++ way is ugly. And then there are all other developers who seem to be way more forward looking, .Net 4.0 MVC, WPF, all those Microsoft X#s, LINQ languages, XML and XSLT, mobile devices and so on. I have done a considerable amount of .NET, SQL, ASPX programming, but the further I go, the less I want to try those technologies. Is that bad? Almost every day I hear people saying that managed code is the only way forward, WPF is the way to go. I hear that C++ is godawful, and you can't code anything in it that's somewhat stable. But I don't buy it. With the experience I have, and the knowledge of how native code is compiled and executes, I can say I find it extremely rare that C++ code is unstable, or leaks, or causes crashes that takes more than 30 seconds to identify and fix. And to tell the truth, I've seen enough problems with other "cool" languages that I'd say C++ is even more stable and production proof than the safe languages, at least for me. The only thing that scares me in C++ is new frameworks, I don't trust them, and I use them extra sparingly. STL - yes, ATL - very sparingly, everything else... Well, not very keen on it. Most huge problems I've ran into, all were related to frameworks, not the language itself. Some overrided operator here, bad hierarchy there, poor class design here, mystical castings there. Other than that, C/C++ (yes, I use them together) still seems a very controlled and stable way to develop applications. Am I stagnating? Should I switch a profession, or force myself in all that marketing hype? Are there more developers who feel the same way?

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How to port animation from one skeleton to another?

- by shawn

While I need to do this in a Blender3D modeler script, the math should be similar for other modelers or realtime engines. Blender3D specific terminology: Armature = skeleton EditBone = rest pose bone (stores the rest pose matrix) PoseBone = can store a different pose (animation matrix) for each frame of your animation I need to share animations (Blender Actions) between Armatures which have EditBones with same names and which have the same positions, but can have different (rest pose) angles and scales. Plus the Armatures might have different bone hierarchy (bone parenting/ no bone parenting). Why I need this: I've made an importer/exporter for a 3d format for a game. The format doesn't store enough info to connect/parent the bones, which makes posing/animating character models in a 3d modeller nearly impossible (original model files for the 3d modeler don't exist, this is for modding). As there are only 2 character skeleton types in the game, I decided to optionally allow to generate the bone from a hardcoded data in the model importer and undo that in the exporter. This allows to easily pose the model for checking weights, easily create weights, makes it easier for Blender to generate automatic weights and of course makes animating possible. This worked perfectly: the importer optionally generated the Armature itself and the exporter removed those changes, so the exported model works with existing animations in the game. But now I'm writing an importer and exporter for the game's animation format and here come the problems of: Trying to make original animations work in Blender with my "custom" (modified) Armature Trying to make animations created by using the "custom" (modified) Armature work with the original models in the game (and Blender). Constraints or bone snapping inside Blender won't work as they don't care that the bones have different angles in the rest pose, they will still face the same direction. It seems I just need to get the "difference" between the EditBone matrices of all EditBones for the two Armatures somehow and apply that difference to PoseBone matrices of all PoseBones, for all frames of my animation. I need to know how to get that difference and how to apply it. BTW, PoseBone matrices are relative to rest pose, they are by default [1.000000, 0.000000, 0.000000, 0.000000](matrix [row 0]) [0.000000, 1.000000, 0.000000, 0.000000](matrix [row 1]) [0.000000, 0.000000, 1.000000, 0.000000](matrix [row 2]) [0.000000, 0.000000, 0.000000, 1.000000](matrix [row 3]) So the question is: How to get the difference between two bone (EditBone) matrices to apply that difference to the animation matrices (PoseBone matrices)? Please be easy on the matrix math.

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Threads are facing deadlock in socket program [migrated]

- by ankur.trapasiya

I am developing one program in which a user can download a number of files. Now first I am sending the list of files to the user. So from the list user selects one file at a time and provides path where to store that file. In turn it also gives the server the path of file where does it exist. I am following this approach because I want to give stream like experience without file size limitation. Here is my code.. 1) This is server which gets started each time I start my application public class FileServer extends Thread { private ServerSocket socket = null; public FileServer() { try { socket = new ServerSocket(Utils.tcp_port); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } @Override public void run() { try { System.out.println("request received"); new FileThread(socket.accept()).start(); } catch (IOException ex) { ex.printStackTrace(); } } } 2) This thread runs for each client separately and sends the requested file to the user 8kb data at a time. public class FileThread extends Thread { private Socket socket; private String filePath; public String getFilePath() { return filePath; } public void setFilePath(String filePath) { this.filePath = filePath; } public FileThread(Socket socket) { this.socket = socket; System.out.println("server thread" + this.socket.isConnected()); //this.filePath = filePath; } @Override public void run() { // TODO Auto-generated method stub try { ObjectInputStream ois=new ObjectInputStream(socket.getInputStream()); try { //************NOTE filePath=(String) ois.readObject(); } catch (ClassNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } File f = new File(this.filePath); byte[] buf = new byte[8192]; InputStream is = new FileInputStream(f); BufferedInputStream bis = new BufferedInputStream(is); ObjectOutputStream oos = new ObjectOutputStream( socket.getOutputStream()); int c = 0; while ((c = bis.read(buf, 0, buf.length)) > 0) { oos.write(buf, 0, c); oos.flush(); // buf=new byte[8192]; } oos.close(); //socket.shutdownOutput(); // client.shutdownOutput(); System.out.println("stop"); // client.shutdownOutput(); ois.close(); // Thread.sleep(500); is.close(); bis.close(); socket.close(); } catch (IOException ex) { ex.printStackTrace(); } } } NOTE: here filePath represents the path of the file where it exists on the server. The client who is connecting to the server provides this path. I am managing this through sockets and I am successfully receiving this path. 3) FileReceiverThread is responsible for receiving the data from the server and constructing file from this buffer data. public class FileReceiveThread extends Thread { private String fileStorePath; private String sourceFile; private Socket socket = null; public FileReceiveThread(String ip, int port, String fileStorePath, String sourceFile) { this.fileStorePath = fileStorePath; this.sourceFile = sourceFile; try { socket = new Socket(ip, port); System.out.println("receive file thread " + socket.isConnected()); } catch (IOException ex) { ex.printStackTrace(); } } @Override public void run() { try { ObjectOutputStream oos = new ObjectOutputStream( socket.getOutputStream()); oos.writeObject(sourceFile); oos.flush(); // oos.close(); File f = new File(fileStorePath); OutputStream os = new FileOutputStream(f); BufferedOutputStream bos = new BufferedOutputStream(os); byte[] buf = new byte[8192]; int c = 0; //************ NOTE ObjectInputStream ois = new ObjectInputStream( socket.getInputStream()); while ((c = ois.read(buf, 0, buf.length)) > 0) { // ois.read(buf); bos.write(buf, 0, c); bos.flush(); // buf = new byte[8192]; } ois.close(); oos.close(); // os.close(); bos.close(); socket.close(); //Thread.sleep(500); } catch (IOException ex) { ex.printStackTrace(); } } } NOTE : Now the problem that I am facing is at the first time when the file is requested the outcome of the program is same as my expectation. I am able to transmit any size of file at first time. Now when the second file is requested (e.g. I have sent file a,b,c,d to the user and user has received file a successfully and now he is requesting file b) the program faces deadlock at this situation. It is waiting for socket's input stream. I put breakpoint and tried to debug it but it is not going in FileThread's run method second time. I could not find out the mistake here. Basically I am making a LAN Messenger which works on LAN. I am using SWT as UI framework.

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How to build a 4x game?

- by Marco

I'm trying to study how succefully implement a 4x game. Area of interest: 1) map data: how to store stellars systems (graphs?), how to generate them and so on.. 2) multiplayer: how to organize code in a non graphical server and a client to display it 3) command system: what are patters to catch user and ai decisions and handle them, adding at first "explore" and "colonize" then "combat", "research", "spy" and so on (commands can affect ships, planets, research, etc..) 4) ai system: ai can use commands to expand, upgrade planets and ship I know is a big questions, so help is appreciated :D 1) Map data Best choice is have a graph to model a galaxy. A node is a stellar system and every system have a list of planets. Ship cannot travel outside of predefined paths, like in Ascendancy: http://www.abandonia.com/files/games/221/Ascendancy_2.png Every connection between two stellar systems have a cost, in turns. Generate a galaxy is only a matter of: - dimension: number of stellar systems, - variety: randomize number of planets and types (desertic, earth, etc..), - positions of each stellar system on game space - connections: assure that exist a path between every node, so graph is "connected" (not sure if this a matematically correct term) 2) Multiplayer Game is organized in turns: player 1, player 2, ai1, ai2. Server take care of all data and clients just diplay it and collect data change. Because is a turn game, latency is not a problem :D 3) Command system I would like to design a hierarchy of commands to take care of this aspect: abstract Genericcommand (target) ExploreCommand (Ship) extends genericcommand colonizeCommand (Ship) buildcommand(planet, object) and so on. In my head all this commands are stored in a queue for every planets, ships or reasearch center or spy, and each turn a command is sent to a server to apply command and change data state 4) ai system I don't have any idea about this. Is a big topic and what I want is a simple ai. Something like "expand and fight against everyone". I think about a behaviour tree to control ai moves, so I can develop an ai that try to build ships to expand and then colonize planets, upgrade them throught science and combat enemies. Could be done with a finite state machine too ? any ideas, resources, article are welcome!

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Subterranean IL: Generics and array covariance

- by Simon Cooper

Arrays in .NET are curious beasts. They are the only built-in collection types in the CLR, and SZ-arrays (single dimension, zero-indexed) have their own commands and IL syntax. One of their stranger properties is they have a kind of built-in covariance long before generic variance was added in .NET 4. However, this causes a subtle but important problem with generics. First of all, we need to briefly recap on array covariance. SZ-array covariance To demonstrate, I'll tweak the classes I introduced in my previous posts: public class IncrementableClass { public int Value; public virtual void Increment(int incrementBy) { Value += incrementBy; } } public class IncrementableClassx2 : IncrementableClass { public override void Increment(int incrementBy) { base.Increment(incrementBy); base.Increment(incrementBy); } } In the CLR, SZ-arrays of reference types are implicitly convertible to arrays of the element's supertypes, all the way up to object (note that this does not apply to value types). That is, an instance of IncrementableClassx2[] can be used wherever a IncrementableClass[] or object[] is required. When an SZ-array could be used in this fashion, a run-time type check is performed when you try to insert an object into the array to make sure you're not trying to insert an instance of IncrementableClass into an IncrementableClassx2[]. This check means that the following code will compile fine but will fail at run-time: IncrementableClass[] array = new IncrementableClassx2[1]; array[0] = new IncrementableClass(); // throws ArrayTypeMismatchException These checks are enforced by the various stelem* and ldelem* il instructions in such a way as to ensure you can't insert a IncrementableClass into a IncrementableClassx2[]. For the rest of this post, however, I'm going to concentrate on the ldelema instruction. ldelema This instruction pops the array index (int32) and array reference (O) off the stack, and pushes a pointer (&) to the corresponding array element. However, unlike the ldelem instruction, the instruction's type argument must match the run-time array type exactly. This is because, once you've got a managed pointer, you can use that pointer to both load and store values in that array element using the ldind* and stind* (load/store indirect) instructions. As the same pointer can be used for both input and output to the array, the type argument to ldelema must be invariant. At the time, this was a perfectly reasonable restriction, and maintained array type-safety within managed code. However, along came generics, and with it the constrained callvirt instruction. So, what happens when we combine array covariance and constrained callvirt? .method public static void CallIncrementArrayValue() { // IncrementableClassx2[] arr = new IncrementableClassx2[1] ldc.i4.1 newarr IncrementableClassx2 // arr[0] = new IncrementableClassx2(); dup newobj instance void IncrementableClassx2::.ctor() ldc.i4.0 stelem.ref // IncrementArrayValue<IncrementableClass>(arr, 0) // here, we're treating an IncrementableClassx2[] as IncrementableClass[] dup ldc.i4.0 call void IncrementArrayValue<class IncrementableClass>(!!0[],int32) // ... ret } .method public static void IncrementArrayValue<(IncrementableClass) T>( !!T[] arr, int32 index) { // arr[index].Increment(1) ldarg.0 ldarg.1 ldelema !!T ldc.i4.1 constrained. !!T callvirt instance void IIncrementable::Increment(int32) ret } And the result: Unhandled Exception: System.ArrayTypeMismatchException: Attempted to access an element as a type incompatible with the array. at IncrementArrayValue[T](T[] arr, Int32 index) at CallIncrementArrayValue() Hmm. We're instantiating the generic method as IncrementArrayValue<IncrementableClass>, but passing in an IncrementableClassx2[], hence the ldelema instruction is failing as it's expecting an IncrementableClass[]. On features and feature conflicts What we've got here is a conflict between existing behaviour (ldelema ensuring type safety on covariant arrays) and new behaviour (managed pointers to object references used for every constrained callvirt on generic type instances). And, although this is an edge case, there is no general workaround. The generic method could be hidden behind several layers of assemblies, wrappers and interfaces that make it a requirement to use array covariance when calling the generic method. Furthermore, this will only fail at runtime, whereas compile-time safety is what generics were designed for! The solution is the readonly. prefix instruction. This modifies the ldelema instruction to ignore the exact type check for arrays of reference types, and so it lets us take the address of array elements using a covariant type to the actual run-time type of the array: .method public static void IncrementArrayValue<(IncrementableClass) T>( !!T[] arr, int32 index) { // arr[index].Increment(1) ldarg.0 ldarg.1 readonly. ldelema !!T ldc.i4.1 constrained. !!T callvirt instance void IIncrementable::Increment(int32) ret } But what about type safety? In return for ignoring the type check, the resulting controlled mutability pointer can only be used in the following situations: As the object parameter to ldfld, ldflda, stfld, call and constrained callvirt instructions As the pointer parameter to ldobj or ldind* As the source parameter to cpobj In other words, the only operations allowed are those that read from the pointer; stind* and similar that alter the pointer itself are banned. This ensures that the array element we're pointing to won't be changed to anything untoward, and so type safety within the array is maintained. This is a typical example of the maxim that whenever you add a feature to a program, you have to consider how that feature interacts with every single one of the existing features. Although an edge case, the readonly. prefix instruction ensures that generics and array covariance work together and that compile-time type safety is maintained. Tune in next time for a look at the .ctor generic type constraint, and what it means.

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XNA RTS A* pathfinding issues

- by Slayter

I'm starting to develop an RTS game using the XNA framework in C# and am still in the very early prototyping stage. I'm working on the basics. I've got unit selection down and am currently working on moving multiple units. I've implemented an A* pathfinding algorithm which works fine for moving a single unit. However when moving multiple units they stack on top of each other. I tried fixing this with a variation of the boids flocking algorithm but this has caused units to sometimes freeze and get stuck trying to move but going no where. Ill post the related methods for moving the units below but ill only post a link to the pathfinding class because its really long and i don't want to clutter up the page. These parts of the code are in the update method for the main controlling class: if (selectedUnits.Count > 0) { int indexOfLeader = 0; for (int i = 0; i < selectedUnits.Count; i++) { if (i == 0) { indexOfLeader = 0; } else { if (Vector2.Distance(selectedUnits[i].position, destination) < Vector2.Distance(selectedUnits[indexOfLeader].position, destination)) indexOfLeader = i; } selectedUnits[i].leader = false; } selectedUnits[indexOfLeader].leader = true; foreach (Unit unit in selectedUnits) unit.FindPath(destination); } foreach (Unit unit in units) { unit.Update(gameTime, selectedUnits); } These three methods control movement in the Unit class: public void FindPath(Vector2 destination) { if (path != null) path.Clear(); Point startPoint = new Point((int)position.X / 32, (int)position.Y / 32); Point endPoint = new Point((int)destination.X / 32, (int)destination.Y / 32); path = pathfinder.FindPath(startPoint, endPoint); pointCounter = 0; if (path != null) nextPoint = path[pointCounter]; dX = 0.0f; dY = 0.0f; stop = false; } private void Move(List<Unit> units) { if (nextPoint == position && !stop) { pointCounter++; if (pointCounter <= path.Count - 1) { nextPoint = path[pointCounter]; if (nextPoint == position) stop = true; } else if (pointCounter >= path.Count) { path.Clear(); pointCounter = 0; stop = true; } } else { if (!stop) { map.occupiedPoints.Remove(this); Flock(units); // Move in X ********* TOOK OUT SPEED ********** if ((int)nextPoint.X > (int)position.X) { position.X += dX; } else if ((int)nextPoint.X < (int)position.X) { position.X -= dX; } // Move in Y if ((int)nextPoint.Y > (int)position.Y) { position.Y += dY; } else if ((int)nextPoint.Y < (int)position.Y) { position.Y -= dY; } if (position == nextPoint && pointCounter >= path.Count - 1) stop = true; map.occupiedPoints.Add(this, position); } if (stop) { path.Clear(); pointCounter = 0; } } } private void Flock(List<Unit> units) { float distanceToNextPoint = Vector2.Distance(position, nextPoint); foreach (Unit unit in units) { float distance = Vector2.Distance(position, unit.position); if (unit != this) { if (distance < space && !leader && (nextPoint != position)) { // create space dX += (position.X - unit.position.X) * 0.1f; dY += (position.Y - unit.position.Y) * 0.1f; if (dX > .05f) nextPoint.X = nextPoint.X - dX; else if (dX < -.05f) nextPoint.X = nextPoint.X + dX; if (dY > .05f) nextPoint.Y = nextPoint.Y - dY; else if (dY < -.05f) nextPoint.Y = nextPoint.Y + dY; if ((dX < .05f && dX > -.05f) && (dY < .05f && dY > -.05f)) stop = true; path[pointCounter] = nextPoint; Console.WriteLine("Make Space: " + dX + ", " + dY); } else if (nextPoint != position && !stop) { dX = speed; dY = speed; Console.WriteLine(dX + ", " + dY); } } } } And here's the link to the pathfinder: https://docs.google.com/open?id=0B_Cqt6txUDkddU40QXBMeTR1djA I hope this post wasn't too long. Also please excuse the messiness of the code. As I said before this is early prototyping. Any help would be appreciated. Thanks!

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A*, Tile costs and heuristic; How to approach

- by Kevin Toet

I'm doing exercises in tile games and AI to improve my programming. I've written a highly unoptimised pathfinder that does the trick and a simple tile class. The first problem i ran into was that the heuristic was rounded to int's which resulted in very straight paths. Resorting a Euclidian Heuristic seemed to fixed it as opposed to use the Manhattan approach. The 2nd problem I ran into was when i tried added tile costs. I was hoping to use the value's of the flags that i set on the tiles but the value's were too small to make the pathfinder consider them a huge obstacle so i increased their value's but that breaks the flags a certain way and no paths were found anymore. So my questions, before posting the code, are: What am I doing wrong that the Manhatten heuristic isnt working? What ways can I store the tile costs? I was hoping to (ab)use the enum flags for this The path finder isnt considering the chance that no path is available, how do i check this? Any code optimisations are welcome as I'd love to improve my coding. public static List<Tile> FindPath( Tile startTile, Tile endTile, Tile[,] map ) { return FindPath( startTile, endTile, map, TileFlags.WALKABLE ); } public static List<Tile> FindPath( Tile startTile, Tile endTile, Tile[,] map, TileFlags acceptedFlags ) { List<Tile> open = new List<Tile>(); List<Tile> closed = new List<Tile>(); open.Add( startTile ); Tile tileToCheck; do { tileToCheck = open[0]; closed.Add( tileToCheck ); open.Remove( tileToCheck ); for( int i = 0; i < tileToCheck.neighbors.Count; i++ ) { Tile tile = tileToCheck.neighbors[ i ]; //has the node been processed if( !closed.Contains( tile ) && ( tile.flags & acceptedFlags ) != 0 ) { //Not in the open list? if( !open.Contains( tile ) ) { //Set G int G = 10; G += tileToCheck.G; //Set Parent tile.parentX = tileToCheck.x; tile.parentY = tileToCheck.y; tile.G = G; //tile.H = Math.Abs(endTile.x - tile.x ) + Math.Abs( endTile.y - tile.y ) * 10; //TODO omg wtf and other incredible stories tile.H = Vector2.Distance( new Vector2( tile.x, tile.y ), new Vector2(endTile.x, endTile.y) ); tile.Cost = tile.G + tile.H + (int)tile.flags; //Calculate H; Manhattan style open.Add( tile ); } //Update the cost if it is else { int G = 10;//cost of going to non-diagonal tiles G += map[ tile.parentX, tile.parentY ].G; //If this path is shorter (G cost is lower) then change //the parent cell, G cost and F cost. if ( G < tile.G ) //if G cost is less, { tile.parentX = tileToCheck.x; //change the square's parent tile.parentY = tileToCheck.y; tile.G = G;//change the G cost tile.Cost = tile.G + tile.H + (int)tile.flags; // add terrain cost } } } } //Sort costs open = open.OrderBy( o => o.Cost).ToList(); } while( tileToCheck != endTile ); closed.Reverse(); List<Tile> validRoute = new List<Tile>(); Tile currentTile = closed[ 0 ]; validRoute.Add( currentTile ); do { //Look up the parent of the current cell. currentTile = map[ currentTile.parentX, currentTile.parentY ]; currentTile.renderer.material.color = Color.green; //Add tile to list validRoute.Add( currentTile ); } while ( currentTile != startTile ); validRoute.Reverse(); return validRoute; } And my Tile class: [Flags] public enum TileFlags: int { NONE = 0, DIRT = 1, STONE = 2, WATER = 4, BUILDING = 8, //handy WALKABLE = DIRT | STONE | NONE, endofenum } public class Tile : MonoBehaviour { //Tile Properties public int x, y; public TileFlags flags = TileFlags.DIRT; public Transform cachedTransform; //A* properties public int parentX, parentY; public int G; public float Cost; public float H; public List<Tile> neighbors = new List<Tile>(); void Awake() { cachedTransform = transform; } }

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WPF Databinding- Part 2 of 3

- by Shervin Shakibi

This is a follow up to my previous post WPF Databinding- Not your fathers databinding Part 1-3 you can download the source code here http://ssccinc.com/wpfdatabinding.zip Example 04 In this example we demonstrate the use of default properties and also binding to an instant of an object which is part of a collection bound to its container. this is actually not as complicated as it sounds. First of all, lets take a look at our Employee class notice we have overridden the ToString method, which will return employees First name , last name and employee number in parentheses, public override string ToString() { return String.Format("{0} {1} ({2})", FirstName, LastName, EmployeeNumber); } in our XAML we have set the itemsource of the list box to just “Binding” and the Grid that contains it, has its DataContext set to a collection of our Employee objects. DataContext="{StaticResource myEmployeeList}"> ….. <ListBox Name="employeeListBox" ItemsSource="{Binding }" Grid.Row="0" /> the ToString in the method for each instance will get executed and the following is a result of it. if we did not have a ToString the list box would look like this: now lets take a look at the grid that will display the details when someone clicks on an Item, the Grid has the following DataContext DataContext="{Binding ElementName=employeeListBox, Path=SelectedItem}"> Which means its bound to a specific instance of the Employee object. and within the gird we have textboxes that are bound to different Properties of our class. <TextBox Grid.Row="0" Grid.Column="1" Text="{Binding Path=FirstName}" /> <TextBox Grid.Row="1" Grid.Column="1" Text="{Binding Path=LastName}" /> <TextBox Grid.Row="2" Grid.Column="1" Text="{Binding Path=Title}" /> <TextBox Grid.Row="3" Grid.Column="1" Text="{Binding Path=Department}" /> Example 05 This project demonstrates use of the ObservableCollection and INotifyPropertyChanged interface. Lets take a look at Employee.cs first, notice it implements the INotifyPropertyChanged interface now scroll down and notice for each setter there is a call to the OnPropertyChanged method, which basically will will fire up the event notifying to the value of that specific property has been changed. Next EmployeeList.cs notice it is an ObservableCollection . Go ahead and set the start up project to example 05 and then run. Click on Add a new employee and the new employee should appear in the list box. Example 06 This is a great example of IValueConverter its actuall a two for one deal, like most of my presentation demos I found this by “Binging” ( formerly known as g---ing) unfortunately now I can’t find the original author to give him the credit he/she deserves. Before we look at the code lets run the app and look at the finished product, put in 0 in Celsius and you should see Fahrenheit textbox displaying to 32 degrees, I know this is calculating correctly from my elementary school science class , also note the color changed to blue, now put in 100 in Celsius which should give us 212 Fahrenheit but now the color is red indicating it is hot, and finally put in 75 Fahrenheit and you should see 23.88 for Celsius and the color now should be black. Basically IValueConverter allows us different types to be bound, I’m sure you have had problems in the past trying to bind to Date values . First look at FahrenheitToCelciusConverter.cs first notice it implements IValueConverter. IValueConverter has two methods Convert and ConvertBack. In each method we have the code for converting Fahrenheit to Celsius and vice Versa. In our XAML, after we set a reference in our Windows.Resources section. and for txtCelsius we set the path to TxtFahrenheit and the converter to an instance our FahrenheitToCelciusConverter converter. no need to repeat this for TxtFahrenheit since we have a convert and ConvertBack. Text="{Binding UpdateSourceTrigger=PropertyChanged, Path=Text,ElementName=txtFahrenheit, Converter={StaticResource myTemperatureConverter}}" As mentioned earlier this is a twofer Demo, in the second demo, we basically are converting a double datatype to a brush. Lets take a look at TemperatureToColorConverter, notice we in our Covert Method, if the value is less than our cold temperature threshold we return a blue brush and if it is higher than our hot temperature threshold we return a redbrush. since we don’t have to convert a brush to double value in our example the convert back is not being implemented. Take time and go through these three examples and I hope you have a better understanding of databinding, ObservableCollection and IValueConverter . Next blog posting we will talk about ValidationRule, DataTemplates and DataTemplate triggers.

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Extended FindWindow

- by João Angelo

The Win32 API provides the FindWindow function that supports finding top-level windows by their class name and/or title. However, the title search does not work if you are trying to match partial text at the middle or the end of the full window title. You can however implement support for these extended search features by using another set of Win32 API like EnumWindows and GetWindowText. A possible implementation follows: using System; using System.Collections.Generic; using System.Linq; using System.Runtime.InteropServices; using System.Text; public class WindowInfo { private IntPtr handle; private string className; internal WindowInfo(IntPtr handle, string title) { if (handle == IntPtr.Zero) throw new ArgumentException("Invalid handle.", "handle"); this.Handle = handle; this.Title = title ?? string.Empty; } public string Title { get; private set; } public string ClassName { get { if (className == null) { className = GetWindowClassNameByHandle(this.Handle); } return className; } } public IntPtr Handle { get { if (!NativeMethods.IsWindow(this.handle)) throw new InvalidOperationException("The handle is no longer valid."); return this.handle; } private set { this.handle = value; } } public static WindowInfo[] EnumerateWindows() { var windows = new List<WindowInfo>(); NativeMethods.EnumWindowsProcessor processor = (hwnd, lParam) => { windows.Add(new WindowInfo(hwnd, GetWindowTextByHandle(hwnd))); return true; }; bool succeeded = NativeMethods.EnumWindows(processor, IntPtr.Zero); if (!succeeded) return new WindowInfo[] { }; return windows.ToArray(); } public static WindowInfo FindWindow(Predicate<WindowInfo> predicate) { WindowInfo target = null; NativeMethods.EnumWindowsProcessor processor = (hwnd, lParam) => { var current = new WindowInfo(hwnd, GetWindowTextByHandle(hwnd)); if (predicate(current)) { target = current; return false; } return true; }; NativeMethods.EnumWindows(processor, IntPtr.Zero); return target; } private static string GetWindowTextByHandle(IntPtr handle) { if (handle == IntPtr.Zero) throw new ArgumentException("Invalid handle.", "handle"); int length = NativeMethods.GetWindowTextLength(handle); if (length == 0) return string.Empty; var buffer = new StringBuilder(length + 1); NativeMethods.GetWindowText(handle, buffer, buffer.Capacity); return buffer.ToString(); } private static string GetWindowClassNameByHandle(IntPtr handle) { if (handle == IntPtr.Zero) throw new ArgumentException("Invalid handle.", "handle"); const int WindowClassNameMaxLength = 256; var buffer = new StringBuilder(WindowClassNameMaxLength); NativeMethods.GetClassName(handle, buffer, buffer.Capacity); return buffer.ToString(); } } internal class NativeMethods { public delegate bool EnumWindowsProcessor(IntPtr hwnd, IntPtr lParam); [DllImport("user32.dll")] [return: MarshalAs(UnmanagedType.Bool)] public static extern bool EnumWindows( EnumWindowsProcessor lpEnumFunc, IntPtr lParam); [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)] public static extern int GetWindowText( IntPtr hWnd, StringBuilder lpString, int nMaxCount); [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)] public static extern int GetWindowTextLength(IntPtr hWnd); [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)] public static extern int GetClassName( IntPtr hWnd, StringBuilder lpClassName, int nMaxCount); [DllImport("user32.dll")] [return: MarshalAs(UnmanagedType.Bool)] public static extern bool IsWindow(IntPtr hWnd); } The access to the windows handle is preceded by a sanity check to assert if it’s still valid, but if you are dealing with windows out of your control then the window can be destroyed right after the check so it’s not guaranteed that you’ll get a valid handle. Finally, to wrap this up a usage, example: static void Main(string[] args) { var w = WindowInfo.FindWindow(wi => wi.Title.Contains("Test.docx")); if (w != null) { Console.Write(w.Title); } }

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Atheros Wireless card shows up as two different models?

- by geermc4

Hi I've been fighting these wireless drivers for a few days and just recently i noticed that the model the Wireless controller appears in lspci is different sometimes. This is the data i have after installing Ubuntu Server 64 bit ~# lspci -k .... 04:00.0 Network controller: Atheros Communications Inc. AR9285 Wireless Network Adapter (PCI-Express) (rev 01) Subsystem: AzureWave Device 1d89 Kernel driver in use: ath9k Kernel modules: ath9k ran some updates, restarted, all was good, all though it did say that linux-headers-server linux-image-server linux-server where beeing kept back. After that i installed ubuntu-desktop (aptitude install ubuntu-desktop --without-recommends) restarted and not only is the wireless not working anymore, but the hardware is listed as a different card ~# lspci -k .... 04:00.0 Ethernet controller: Atheros Communications Inc. AR5008 Wireless Network Adapter (rev 01) has no available drivers for it, still i tried to modprobe ath9k, they show up in lsmod as loaded, but still iw list shows nothing. this is what it looked like before the ubuntu-desktop instalation Wiphy phy0 Band 1: Capabilities: 0x11ce HT20/HT40 SM Power Save disabled RX HT40 SGI TX STBC RX STBC 1-stream Max AMSDU length: 3839 bytes DSSS/CCK HT40 Maximum RX AMPDU length 65535 bytes (exponent: 0x003) Minimum RX AMPDU time spacing: 8 usec (0x06) HT TX/RX MCS rate indexes supported: 0-7 Frequencies: * 2412 MHz [1] (14.0 dBm) * 2417 MHz [2] (15.0 dBm) * 2422 MHz [3] (15.0 dBm) * 2427 MHz [4] (15.0 dBm) * 2432 MHz [5] (15.0 dBm) * 2437 MHz [6] (15.0 dBm) * 2442 MHz [7] (15.0 dBm) * 2447 MHz [8] (15.0 dBm) * 2452 MHz [9] (15.0 dBm) * 2457 MHz [10] (15.0 dBm) * 2462 MHz [11] (15.0 dBm) * 2467 MHz [12] (15.0 dBm) (passive scanning) * 2472 MHz [13] (14.0 dBm) (passive scanning) * 2484 MHz [14] (17.0 dBm) (passive scanning) Bitrates (non-HT): * 1.0 Mbps * 2.0 Mbps (short preamble supported) * 5.5 Mbps (short preamble supported) * 11.0 Mbps (short preamble supported) * 6.0 Mbps * 9.0 Mbps * 12.0 Mbps * 18.0 Mbps * 24.0 Mbps * 36.0 Mbps * 48.0 Mbps * 54.0 Mbps max # scan SSIDs: 4 max scan IEs length: 2257 bytes Coverage class: 0 (up to 0m) Supported Ciphers: * WEP40 (00-0f-ac:1) * WEP104 (00-0f-ac:5) * TKIP (00-0f-ac:2) * CCMP (00-0f-ac:4) * CMAC (00-0f-ac:6) Available Antennas: TX 0x1 RX 0x3 Configured Antennas: TX 0x1 RX 0x3 Supported interface modes: * IBSS * managed * AP * AP/VLAN * WDS * monitor * mesh point * P2P-client * P2P-GO software interface modes (can always be added): * AP/VLAN * monitor interface combinations are not supported Supported commands: * new_interface * set_interface * new_key * new_beacon * new_station * new_mpath * set_mesh_params * set_bss * authenticate * associate * deauthenticate * disassociate * join_ibss * join_mesh * remain_on_channel * set_tx_bitrate_mask * action * frame_wait_cancel * set_wiphy_netns * set_channel * set_wds_peer * connect * disconnect Supported TX frame types: * IBSS: 0x0000 0x0010 0x0020 0x0030 0x0040 0x0050 0x0060 0x0070 0x0080 0x0090 0x00a0 0x00b0 0x00c0 0x00d0 0x00e0 0x00f0 * managed: 0x0000 0x0010 0x0020 0x0030 0x0040 0x0050 0x0060 0x0070 0x0080 0x0090 0x00a0 0x00b0 0x00c0 0x00d0 0x00e0 0x00f0 * AP: 0x0000 0x0010 0x0020 0x0030 0x0040 0x0050 0x0060 0x0070 0x0080 0x0090 0x00a0 0x00b0 0x00c0 0x00d0 0x00e0 0x00f0 * AP/VLAN: 0x0000 0x0010 0x0020 0x0030 0x0040 0x0050 0x0060 0x0070 0x0080 0x0090 0x00a0 0x00b0 0x00c0 0x00d0 0x00e0 0x00f0 * mesh point: 0x0000 0x0010 0x0020 0x0030 0x0040 0x0050 0x0060 0x0070 0x0080 0x0090 0x00a0 0x00b0 0x00c0 0x00d0 0x00e0 0x00f0 * P2P-client: 0x0000 0x0010 0x0020 0x0030 0x0040 0x0050 0x0060 0x0070 0x0080 0x0090 0x00a0 0x00b0 0x00c0 0x00d0 0x00e0 0x00f0 * P2P-GO: 0x0000 0x0010 0x0020 0x0030 0x0040 0x0050 0x0060 0x0070 0x0080 0x0090 0x00a0 0x00b0 0x00c0 0x00d0 0x00e0 0x00f0 Supported RX frame types: * IBSS: 0x00d0 * managed: 0x0040 0x00d0 * AP: 0x0000 0x0020 0x0040 0x00a0 0x00b0 0x00c0 0x00d0 * AP/VLAN: 0x0000 0x0020 0x0040 0x00a0 0x00b0 0x00c0 0x00d0 * mesh point: 0x00b0 0x00c0 0x00d0 * P2P-client: 0x0040 0x00d0 * P2P-GO: 0x0000 0x0020 0x0040 0x00a0 0x00b0 0x00c0 0x00d0 Device supports RSN-IBSS. What's with the hardware change? If it has 2, how can i make the AR9285 always load and disable AR5008, or, is it the same and it's just showing it different? :| Oh and I've tried this on Ubuntu 10.04 server, xubuntu 12.04, ubuntu 12.04 desktop and server. Thanks in advanced. -- Here's some more info, i have it setup in 2 hard drives, 1 works and the other one i'm using to figure it out The one that works... # lshw -class network *-network description: Ethernet interface product: RTL8111/8168B PCI Express Gigabit Ethernet controller vendor: Realtek Semiconductor Co., Ltd. physical id: 0 bus info: pci@0000:03:00.0 logical name: eth0 version: 06 serial: 54:04:a6:a3:3b:96 size: 1Gbit/s capacity: 1Gbit/s width: 64 bits clock: 33MHz capabilities: pm msi pciexpress msix vpd bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=full firmware=rtl_nic/rtl8168e-2.fw ip=192.168.2.147 latency=0 link=yes multicast=yes port=MII speed=1Gbit/s resources: irq:43 ioport:e000(size=256) memory:d0004000-d0004fff memory:d0000000-d0003fff *-network description: Wireless interface product: AR9285 Wireless Network Adapter (PCI-Express) vendor: Atheros Communications Inc. physical id: 0 bus info: pci@0000:04:00.0 logical name: wlan0 version: 01 serial: 74:2f:68:4a:26:73 width: 64 bits clock: 33MHz capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless configuration: broadcast=yes driver=ath9k driverversion=3.2.0-18-generic-pae firmware=N/A latency=0 link=no multicast=yes wireless=IEEE 802.11bgn resources: irq:18 memory:fea00000-fea0ffff Here's where it doesn't # lshw -class network *-network description: Ethernet interface product: RTL8111/8168B PCI Express Gigabit Ethernet controller vendor: Realtek Semiconductor Co., Ltd. physical id: 0 bus info: pci@0000:03:00.0 logical name: eth0 version: 06 serial: 54:04:a6:a3:3b:96 size: 1Gbit/s capacity: 1Gbit/s width: 64 bits clock: 33MHz capabilities: pm msi pciexpress msix vpd bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=full firmware=rtl_nic/rtl8168e-2.fw ip=192.168.2.160 latency=0 link=yes multicast=yes port=MII speed=1Gbit/s resources: irq:43 ioport:e000(size=256) memory:d0004000-d0004fff memory:d0000000-d0003fff *-network UNCLAIMED description: Ethernet controller product: AR5008 Wireless Network Adapter vendor: Atheros Communications Inc. physical id: 0 bus info: pci@0000:04:00.0 version: 01 width: 64 bits clock: 33MHz capabilities: pm msi pciexpress bus_master cap_list configuration: latency=0 resources: memory:fea00000-fea0ffff Update I've noticed that if i blacklist the ath9k and ath9k_common modules lspci gives me the AR9285, but then I need to modprobe ath9k for it to work, does this make any sense? If so, why?

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How to Overcome or fix MIXED_DML_OPERATION error in Salesforce APEX without future method ?

- by sathya

How to Overcome or fix MIXED_DML_OPERATION error in Salesforce APEX without future method ?MIXED_DML_OPERATION :-one of the worst issues we have ever faced :)While trying to perform DML operation on a setup object and non-setup object in a single action you will face this error.Following are the solutions I tried and the final one worked out :-1. perform the 1st objects DML on normal apex method. Then Call the 2nd objects DML through a future method. Drawback :- You cant get a response from the future method as its context is different and because its executing asynchronously and that its static.2. Tried the following option but it didnt work :- 1. perform the dml operation on the normal apex method. 2. tried calling the 2nd dml from trigger thinking that it would be in a different context. But it didnt work. 3. Some suggestions were given in some blogs that we could try System.runas() Unfortunately that works only for test class. 4. Finally achieved it with response synchronously through the following solution :- a. Created 2 apex:commandbuttons :- 1. <apex:commandButton value="Save and Send Activation Email" action="{!CreateContact}" rerender="junkpanel" oncomplete="callSimulateUserSave()"> Note :- Oncomplete will not work if you dont have a rerender attribute. So just try refreshing a junk panel. 2. <apex:commandButton value="SimulateUserSave" id="SimulateUserSave" action="{!SaveUser}" style="display:none;margin-left:5px;"/> Have a junk panel as well just for rerendering :- <apex:outputPanel id="junkpanel"></apex:outputPanel> b. Created this javascript function which is called from first button's oncomplete and clicks the second button :- function callSimulateUserSave() { // Specify the id of the button that needs to be clicked. This id is based on the Apex Component Hierarchy. // You will not get this value if you dont have the id attribute in the button which needs to be clicked from javascript // If you have any doubt in getting this value. Just hover over the button using Chrome developer tools to get the id. // But it will show like theForm:SimulateUserSave but you need to replace the colon with a dot here. // Note :- I have given display:none in the style of the second button to make sure that, it is not visible for the user. var mybtn=document.getElementById('{!$Component.theForm.SimulateUserSave}'); mybtn.click(); } c. Apex Methods CreateContact and SaveUser are the pagereference methods which contains the code to create contact and user respectively. After inserting the user inside the second apex method you can just set some public Properties in the page, for ex:- created userid to get the user details and display in the page to show the acknowledgement to the users that the User is created.

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Composing Silverlight Applications With MEF

- by PeterTweed

Anyone who has written an application with complexity enough to warrant multiple controls on multiple pages/forms should understand the benefit of composite application development. That is defining your application architecture that can be separated into separate pieces each with it’s own distinct purpose that can then be “composed” together into the solution. Composition can be useful in any layer of the application, from the presentation layer, the business layer, common services or data access. Historically people have had different options to achieve composing applications from distinct well known pieces – their own version of dependency injection, containers to aid with composition like Unity, the composite application guidance for WPF and Silverlight and before that the composite application block. Microsoft has been working on another mechanism to aid composition and extension of applications for some time now – the Managed Extensibility Framework or MEF for short. With Silverlight 4 it is part of the Silverlight environment. MEF allows a much simplified mechanism for composition and extensibility compared to other mechanisms – which has always been the primary issue for adoption of the earlier mechanisms/frameworks. This post will guide you through the simple use of MEF for the scenario of composition of an application – using exports, imports and composition. Steps: 1. Create a new Silverlight 4 application. 2. Add references to the following assemblies: System.ComponentModel.Composition.dll System.ComponentModel.Composition.Initialization.dll 3. Add a new user control called LeftControl. 4. Replace the LayoutRoot Grid with the following xaml: <Grid x:Name="LayoutRoot" Background="Beige" Margin="40" > <Button Content="Left Content" Margin="30"></Button> </Grid> 5. Add the following statement to the top of the LeftControl.xaml.cs file using System.ComponentModel.Composition; 6. Add the following attribute to the LeftControl class [Export(typeof(LeftControl))] This attribute tells MEF that the type LeftControl will be exported – i.e. made available for other applications to import and compose into the application. 7. Add a new user control called RightControl. 8. Replace the LayoutRoot Grid with the following xaml: <Grid x:Name="LayoutRoot" Background="Green" Margin="40" > <TextBlock Margin="40" Foreground="White" Text="Right Control" FontSize="16" VerticalAlignment="Center" HorizontalAlignment="Center" ></TextBlock> </Grid> 9. Add the following statement to the top of the RightControl.xaml.cs file using System.ComponentModel.Composition; 10. Add the following attribute to the RightControl class [Export(typeof(RightControl))] 11. Add the following xaml to the LayoutRoot Grid in MainPage.xaml: <StackPanel Orientation="Horizontal" HorizontalAlignment="Center"> <Border Name="LeftContent" Background="Red" BorderBrush="Gray" CornerRadius="20"></Border> <Border Name="RightContent" Background="Red" BorderBrush="Gray" CornerRadius="20"></Border> </StackPanel> The borders will hold the controls that will be imported and composed via MEF. 12. Add the following statement to the top of the MainPage.xaml.cs file using System.ComponentModel.Composition; 13. Add the following properties to the MainPage class: [Import(typeof(LeftControl))] public LeftControl LeftUserControl { get; set; } [Import(typeof(RightControl))] public RightControl RightUserControl { get; set; } This defines properties accepting LeftControl and RightControl types. The attrributes are used to tell MEF the discovered type that should be applied to the property when composition occurs. 14. Replace the MainPage constructore with the following code: public MainPage() { InitializeComponent(); CompositionInitializer.SatisfyImports(this); LeftContent.Child = LeftUserControl; RightContent.Child = RightUserControl; } The CompositionInitializer.SatisfyImports(this) function call tells MEF to discover types related to the declared imports for this object (the MainPage object). At that point, types matching those specified in the import defintions are discovered in the executing assembly location of the application and instantiated and assigned to the matching properties of the current object. 15. Run the application and you will see the left control and right control types displayed in the MainPage: Congratulations! You have used MEF to dynamically compose user controls into a parent control in a composite application model. In the next post we will build on this topic to cover using MEF to compose Silverlight applications dynamically in download on demand scenarios – so .xap packages can be downloaded only when needed, avoiding large initial download for the main application xap. Take the Slalom Challenge at www.slalomchallenge.com!

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await, WhenAll, WaitAll, oh my!!

- by cibrax

If you are dealing with asynchronous work in .NET, you might know that the Task class has become the main driver for wrapping asynchronous calls. Although this class was officially introduced in .NET 4.0, the programming model for consuming tasks was much more simplified in C# 5.0 in .NET 4.5 with the addition of the new async/await keywords. In a nutshell, you can use these keywords to make asynchronous calls as if they were sequential, and avoiding in that way any fork or callback in the code. The compiler takes care of the rest. I was yesterday writing some code for making multiple asynchronous calls to backend services in parallel. The code looked as follow, var allResults = new List<Result>(); foreach(var provider in providers) { var results = await provider.GetResults(); allResults.AddRange(results); } return allResults; You see, I was using the await keyword to make multiple calls in parallel. Something I did not consider was the overhead this code implied after being compiled. I started an interesting discussion with some smart folks in twitter. One of them, Tugberk Ugurlu, had the brilliant idea of actually write some code to make a performance comparison with another approach using Task.WhenAll. There are two additional methods you can use to wait for the results of multiple calls in parallel, WhenAll and WaitAll. WhenAll creates a new task and waits for results in that new task, so it does not block the calling thread. WaitAll, on the other hand, blocks the calling thread. This is the code Tugberk initially wrote, and I modified afterwards to also show the results of WaitAll. class Program { private static Func<Stopwatch, Task>[] funcs = new Func<Stopwatch, Task>[] { async (watch) => { watch.Start(); await Task.Delay(1000); Console.WriteLine("1000 one has been completed."); }, async (watch) => { await Task.Delay(1500); Console.WriteLine("1500 one has been completed."); }, async (watch) => { await Task.Delay(2000); Console.WriteLine("2000 one has been completed."); watch.Stop(); Console.WriteLine(watch.ElapsedMilliseconds + "ms has been elapsed."); } }; static void Main(string[] args) { Console.WriteLine("Await in loop work starts..."); DoWorkAsync().ContinueWith(task => { Console.WriteLine("Parallel work starts..."); DoWorkInParallelAsync().ContinueWith(t => { Console.WriteLine("WaitAll work starts..."); WaitForAll(); }); }); Console.ReadLine(); } static async Task DoWorkAsync() { Stopwatch watch = new Stopwatch(); foreach (var func in funcs) { await func(watch); } } static async Task DoWorkInParallelAsync() { Stopwatch watch = new Stopwatch(); await Task.WhenAll(funcs[0](watch), funcs[1](watch), funcs[2](watch)); } static void WaitForAll() { Stopwatch watch = new Stopwatch(); Task.WaitAll(funcs[0](watch), funcs[1](watch), funcs[2](watch)); } } After running this code, the results were very concluding. Await in loop work starts... 1000 one has been completed. 1500 one has been completed. 2000 one has been completed. 4532ms has been elapsed. Parallel work starts... 1000 one has been completed. 1500 one has been completed. 2000 one has been completed. 2007ms has been elapsed. WaitAll work starts... 1000 one has been completed. 1500 one has been completed. 2000 one has been completed. 2009ms has been elapsed. The await keyword in a loop does not really make the calls in parallel.

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Reporting on common code smells : A POC

- by Dave Ballantyne

Over the past few blog entries, I’ve been looking at parsing TSQL scripts in a variety of ways for a variety of tasks. In my last entry ‘How to prevent ‘Select *’ : The elegant way’, I looked at parsing SQL to report upon uses of SELECT *. The obvious question leading on from this is, “Great, what about other code smells ?” Well, using the language service parser to do that was turning out to be a bit of a hard job, sure I was getting tokens but no real context. I wasn't even being told when an end of statement had been reached. One of the other parsing options available from Microsoft is exposed in the assembly ‘Microsoft.SqlServer.TransactSql.ScriptDom’, this is ,I believe, installed with the client development tools with SQLServer. It is much more feature rich than the original parser I had used and breaks a TSQL script into intuitive classes for analysis. So, what sort of smells can I now find using it ? Well, for an opening gambit quite a nice little list. Use of NOLOCK Set of READ UNCOMMITTED Use of SELECT * Insert without column references Explicit datatype conversion on Sargs Cross server selects Non use of two-part naming convention Table and Query hint usage Changes in set options Use of single line comments Use of ordinal column positions in ORDER BY clause Now, lets not argue the point that “It depends” as smells on some of these, but as an academic exercise it is quite interesting. The code is available from this link :https://www.dropbox.com/s/rfk32sou4fzl2cw/TSQLDomTest.zip All the usual disclaimers apply to this code, I cannot be held responsible for anything ranging from mild annoyance through to universe destruction due to the use of this code or examples. The zip file contains a powershell script and my test cases. The assembly used requires .Net 4 to run, which means that you will need powershell 3 ( though im running through PowerGUI and all works ok ) . The code searches for all .sql files in the folder hierarchy for the workingpath, you can override this if you want by simply changing the $Folder variable, and processes each in turn for the smells. Feedback is not great at the moment, all it does is output to an xml file (Smells.xml) the offset position and a description of the smell found. Right now, I am interested in your feedback. What do you think ? Is this (or should it be) more than an academic exercise ? Can tooling such as this be used as some form of code quality measure ? Does it Work ? Do you have a case listed above which is not being reported ? Do you have a case that you would love to be reported ? Let me know , please mailto: [email protected]. Thanks

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how to label a cuboid using open gl?

- by usha

hi this is how my 3dcuboid looks ,i have attached complete code , i want to label this cuboid using different name across sides how is it possible using opengl in android...plz help me out public class MyGLRenderer implements Renderer { Context context; Cuboid rect; private float mCubeRotation; // private static float angleCube = 0; // Rotational angle in degree for cube (NEW) // private static float speedCube = -1.5f; // Rotational speed for cube (NEW) public MyGLRenderer(Context context) { rect = new Cuboid(); this.context = context; } public void onDrawFrame(GL10 gl) { // TODO Auto-generated method stub gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT); gl.glLoadIdentity(); // Reset the model-view matrix gl.glTranslatef(0.2f, 0.0f, -8.0f); // Translate right and into the screen gl.glScalef(0.8f, 0.8f, 0.8f); // Scale down (NEW) gl.glRotatef(mCubeRotation, 1.0f, 1.0f, 1.0f); // gl.glRotatef(angleCube, 1.0f, 1.0f, 1.0f); // rotate about the axis (1,1,1) (NEW) rect.draw(gl); mCubeRotation -= 0.15f; //angleCube += speedCube; } public void onSurfaceChanged(GL10 gl, int width, int height) { // TODO Auto-generated method stub if (height == 0) height = 1; // To prevent divide by zero float aspect = (float)width / height; // Set the viewport (display area) to cover the entire window gl.glViewport(0, 0, width, height); // Setup perspective projection, with aspect ratio matches viewport gl.glMatrixMode(GL10.GL_PROJECTION); // Select projection matrix gl.glLoadIdentity(); // Reset projection matrix // Use perspective projection GLU.gluPerspective(gl, 45, aspect, 0.1f, 100.f); gl.glMatrixMode(GL10.GL_MODELVIEW); // Select model-view matrix gl.glLoadIdentity(); // Reset } public void onSurfaceCreated(GL10 gl, EGLConfig config) { // TODO Auto-generated method stub gl.glClearColor(0.0f, 0.0f, 0.0f, 1.0f); // Set color's clear-value to black gl.glClearDepthf(1.0f); // Set depth's clear-value to farthest gl.glEnable(GL10.GL_DEPTH_TEST); // Enables depth-buffer for hidden surface removal gl.glDepthFunc(GL10.GL_LEQUAL); // The type of depth testing to do gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_NICEST); // nice perspective view gl.glShadeModel(GL10.GL_SMOOTH); // Enable smooth shading of color gl.glDisable(GL10.GL_DITHER); // Disable dithering for better performance }} public class Cuboid{ private FloatBuffer mVertexBuffer; private FloatBuffer mColorBuffer; private ByteBuffer mIndexBuffer; private float vertices[] = { //width,height,depth -2.5f, -1.0f, -1.0f, 1.0f, -1.0f, -1.0f, 1.0f, 1.0f, -1.0f, -2.5f, 1.0f, -1.0f, -2.5f, -1.0f, 1.0f, 1.0f, -1.0f, 1.0f, 1.0f, 1.0f, 1.0f, -2.5f, 1.0f, 1.0f }; private float colors[] = { // R,G,B,A COLOR 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f, 0.5f, 0.0f, 1.0f, 1.0f, 0.5f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f, 1.0f }; private byte indices[] = { // VERTEX 0,1,2,3,4,5,6,7 REPRESENTATION FOR FACES 0, 4, 5, 0, 5, 1, 1, 5, 6, 1, 6, 2, 2, 6, 7, 2, 7, 3, 3, 7, 4, 3, 4, 0, 4, 7, 6, 4, 6, 5, 3, 0, 1, 3, 1, 2 }; public Cuboid() { ByteBuffer byteBuf = ByteBuffer.allocateDirect(vertices.length * 4); byteBuf.order(ByteOrder.nativeOrder()); mVertexBuffer = byteBuf.asFloatBuffer(); mVertexBuffer.put(vertices); mVertexBuffer.position(0); byteBuf = ByteBuffer.allocateDirect(colors.length * 4); byteBuf.order(ByteOrder.nativeOrder()); mColorBuffer = byteBuf.asFloatBuffer(); mColorBuffer.put(colors); mColorBuffer.position(0); mIndexBuffer = ByteBuffer.allocateDirect(indices.length); mIndexBuffer.put(indices); mIndexBuffer.position(0); } public void draw(GL10 gl) { gl.glFrontFace(GL10.GL_CW); gl.glVertexPointer(3, GL10.GL_FLOAT, 0, mVertexBuffer); gl.glColorPointer(4, GL10.GL_FLOAT, 0, mColorBuffer); gl.glEnableClientState(GL10.GL_VERTEX_ARRAY); gl.glEnableClientState(GL10.GL_COLOR_ARRAY); gl.glDrawElements(GL10.GL_TRIANGLES, 36, GL10.GL_UNSIGNED_BYTE, mIndexBuffer); gl.glDisableClientState(GL10.GL_VERTEX_ARRAY); gl.glDisableClientState(GL10.GL_COLOR_ARRAY); } } public class Draw3drect extends Activity { private GLSurfaceView glView; // Use GLSurfaceView // Call back when the activity is started, to initialize the view @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); glView = new GLSurfaceView(this); // Allocate a GLSurfaceView glView.setRenderer(new MyGLRenderer(this)); // Use a custom renderer this.setContentView(glView); // This activity sets to GLSurfaceView } // Call back when the activity is going into the background @Override protected void onPause() { super.onPause(); glView.onPause(); } // Call back after onPause() @Override protected void onResume() { super.onResume(); glView.onResume(); } }

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Thread.Interrupt Is Evil

- by Alois Kraus

Recently I have found an interesting issue with Thread.Interrupt during application shutdown. Some application was crashing once a week and we had not really a clue what was the issue. Since it happened not very often it was left as is until we have got some memory dumps during the crash. A memory dump usually means WindDbg which I really like to use (I know I am one of the very few fans of it). After a quick analysis I did find that the main thread already had exited and the thread with the crash was stuck in a Monitor.Wait. Strange Indeed. Running the application a few thousand times under the debugger would potentially not have shown me what the reason was so I decided to what I call constructive debugging. I did create a simple Console application project and try to simulate the exact circumstances when the crash did happen from the information I have via memory dump and source code reading. The thread that was crashing was actually MS code from an old version of the Microsoft Caching Application Block. From reading the code I could conclude that the main thread did call the Dispose method on the CacheManger class which did call Thread.Interrupt on the cache scavenger thread which was just waiting for work to do. My first version of the repro looked like this static void Main(string[] args) { Thread t = new Thread(ThreadFunc) { IsBackground = true, Name = "Test Thread" }; t.Start(); Console.WriteLine("Interrupt Thread"); t.Interrupt(); } static void ThreadFunc() { while (true) { object value = Dequeue(); // block until unblocked or awaken via ThreadInterruptedException } } static object WaitObject = new object(); static object Dequeue() { object lret = "got value"; try { lock (WaitObject) { } } catch (ThreadInterruptedException) { Console.WriteLine("Got ThreadInterruptException"); lret = null; } return lret; } I do start a background thread and call Thread.Interrupt on it and then directly let the application terminate. The thread in the meantime does plenty of Monitor.Enter/Leave calls to simulate work on it. This first version did not crash. So I need to dig deeper. From the memory dump I did know that the finalizer thread was doing just some critical finalizers which were closing file handles. Ok lets add some long running finalizers to the sample. class FinalizableObject : CriticalFinalizerObject { ~FinalizableObject() { Console.WriteLine("Hi we are waiting to finalize now and block the finalizer thread for 5s."); Thread.Sleep(5000); } } class Program { static void Main(string[] args) { FinalizableObject fin = new FinalizableObject(); Thread t = new Thread(ThreadFunc) { IsBackground = true, Name = "Test Thread" }; t.Start(); Console.WriteLine("Interrupt Thread"); t.Interrupt(); GC.KeepAlive(fin); // prevent finalizing it too early // After leaving main the other thread is woken up via Thread.Abort // while we are finalizing. This causes a stackoverflow in the CLR ThreadAbortException handling at this time. } With this changed Main method and a blocking critical finalizer I did get my crash just like the real application. The funny thing is that this is actually a CLR bug. When the main method is left the CLR does suspend all threads except the finalizer thread and declares all objects as garbage. After the normal finalizers were called the critical finalizers are executed to e.g. free OS handles (usually). Remember that I did call Thread.Interrupt as one of the last methods in the Main method. The Interrupt method is actually asynchronous and does wake a thread up and throws a ThreadInterruptedException only once unlike Thread.Abort which does rethrow the exception when an exception handling clause is left. It seems that the CLR does not expect that a frozen thread does wake up again while the critical finalizers are executed. While trying to raise a ThreadInterrupedException the CLR goes down with an stack overflow. Ups not so nice. Why has this nobody noticed for years is my next question. As it turned out this error does only happen on the CLR for .NET 4.0 (x86 and x64). It does not show up in earlier or later versions of the CLR. I have reported this issue on connect here but so far it was not confirmed as a CLR bug. But I would be surprised if my console application was to blame for a stack overflow in my test thread in a Monitor.Wait call. What is the moral of this story? Thread.Abort is evil but Thread.Interrupt is too. It is so evil that even the CLR of .NET 4.0 contains a race condition during the CLR shutdown. When the CLR gurus can get it wrong the chances are high that you get it wrong too when you use this constructs. If you do not believe me see what Patrick Smacchia does blog about Thread.Abort and List.Sort. Not only the CLR creators can get it wrong. The BCL writers do sometimes have a hard time with correct exception handling as well. If you do tell me that you use Thread.Abort frequently and never had problems with it I do suspect that you do not have looked deep enough into your application to find such sporadic errors.

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Upgrading to Code Based Migrations EF 4.3.1 with Connector/Net 6.6

- by GABMARTINEZ

Entity Framework 4.3.1 includes a new feature called code first migrations. We are adding support for this feature in our upcoming 6.6 release of Connector/Net. In this walk-through we'll see the workflow of code-based migrations when you have an existing application and you would like to upgrade to this EF 4.3.1 version and use this approach, so you can keep track of the changes that you do to your database. The first thing we need to do is add the new Entity Framework 4.3.1 package to our application. This should via the NuGet package manager. You can read more about why EF is not part of the .NET framework here. Adding EF 4.3.1 to our existing application Inside VS 2010 go to Tools -> Library Package Manager -> Package Manager Console, this will open the Power Shell Host Window where we can work with all the EF commands. In order to install this library to your existing application you should type Install-Package EntityFramework This will make some changes to your application. So Let's check them. In your .config file you'll see a <configSections> which contains the version you have from EntityFramework and also was added the <entityFramework> section as shown below. This section is by default configured to use SQL Express which won't be necesary for this case. So you can comment it out or leave it empty. Also please make sure you're using the Connector/Net 6.6.x version which is the one that has this support as is shown in the previous image. At this point we face one issue; in order to be able to work with Migrations we need the __MigrationHistory table that we don't have yet since our Database was created with an older version. This table is used to keep track of the changes in our model. So we need to get it in our existing Database. Getting a Migration-History table into an existing database First thing we need to do to enable migrations in our existing application is to create our configuration class which will set up the MySqlClient Provider as our SQL Generator. So we have to add it with the following code: using System.Data.Entity.Migrations; //add this at the top of your cs file public class Configuration : DbMigrationsConfiguration<NameOfYourDbContext> //Make sure to use the name of your existing DBContext { public Configuration() { this.AutomaticMigrationsEnabled = false; //Set Automatic migrations to false since we'll be applying the migrations manually for this case. SetSqlGenerator("MySql.Data.MySqlClient", new MySql.Data.Entity.MySqlMigrationSqlGenerator()); } } This code will set up our configuration that we'll be using when executing all the migrations for our application. Once we have done this we can Build our application so we can check that everything is fine. Creating our Initial Migration Now let's add our Initial Migration. In Package Manager Console, execute "add-migration InitialCreate", you can use any other name but I like to set this as our initial create for future reference. After we run this command, some changes were done in our application: A new Migrations Folder was created. A new class migration call InitialCreate which in most of the cases should have empty Up and Down methods as long as your database is up to date with your Model. Since all your entities already exists, delete all duplicated code to create any entity which exists already in your Database if there is any. I found this easier when you don't have any pending updates to do to your database. Now we have our empty migration that will make no changes in our database and represents how are all the things at the begining of our migrations. Finally, let's create our MigrationsHistory table. Optionally you can add SQL code to delete the edmdata table which is not needed anymore. public override void Up() { // Just make sure that you used 4.1 or later version Sql("DROP TABLE EdmMetadata"); } From our Package Manager Console let's type: Update-database; If you like to see the operations made on each Update-database command you can use the flag -verbose after the Update-database. This will make two important changes. It will execute the Up method in the initial migration which has no changes in the database. And second, and very important, it will create the __MigrationHistory table necessary to keep track of your changes. And next time you make a change to your database it will compare the current model to the one stored in the Model Column of this table. Conclusion The important thing of this walk through is that we must create our initial migration before we start doing any changes to our model. This way we'll be adding the necessary __MigrationsHistory table to our existing database, so we can keep our database up to date with all the changes we do in our context model using migrations. Hope you have found this information useful. Please let us know if you have any questions or comments, also please check our forums here where we keep answering questions in general for the community. Happy MySQL/Net Coding!

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Creating ADF Faces Comamnd Button at Runtime

- by Frank Nimphius

Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} In ADF Faces, the command button is an instance of RichCommandButton and can be created at runtime. While creating the button is not difficult at all, adding behavior to it requires knowing about how to dynamically create and add an action listener reference. The example code below shows two methods: The first method, handleButtonPress is a public method exposed on a managed bean. public void handleButtonPress(ActionEvent event){ System.out.println("Event handled"); //optional: partially refresh changed components if command //issued as a partial submit } The second method is called in response to a user interaction or on page load and dynamically creates and adds a command button. When the button is pressed, the managed bean method – the action handler – defined above is called. The action handler is referenced using EL in the created MethodExpression instance. If the managed bean is in viewScope, backingBeanScope or pageFlowsScope, then you need to add these scopes as a prefix to the EL (as you would when configuring the managed bean reference at design time) //Create command button and add it as a child to the parent component that is passed as an //argument to this method private void reateCommandButton(UIComponent parent){ RichCommandButton edit = new RichCommandButton(); //make the request partial edit.setPartialSubmit(true); edit.setText("Edit"); //compose the method expression to invoke the event handler FacesContext fctx = FacesContext.getCurrentInstance(); Application application = fctx.getApplication(); ExpressionFactory elFactory = application.getExpressionFactory(); ELContext elContext = facesCtx.getELContext(); MethodExpression methodExpressio = null; //Make sure the EL expression references a valid managed bean method. Ensure //the bean scope is properly addressed methodExpression = elFactory.createMethodExpression( elContext,"#{myRequestScopeBean.handleButtonPress}", Object.class,new Class[] {ActionEvent.class}); //Create the command buttonaction listener reference MethodExpressionActionListener al = null; al= new MethodExpressionActionListener(methodExpression); edit.addActionListener(al); //add new command button to parent component and PPR the component for //the button to show parent.getChildren().add(edit); AdfFacesContext adfFacesContext = AdfFacesContext.getCurrentInstance(); adfFacesContext.addPartialTarget(parent); }

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How do you test an ICF based connector using Connector Facade Standalone?

- by Shashidhar Malyala

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} The following code helps in writing a standalone java program to test an ICF based connector. The sample code in this example takes into account an ICF based flatfile connector. It is possible to test various operations like create, update, delete, search etc... It is also possible to set values to the connector configuration parameters, add/remove attributes and their values. public class FlatFile { private static final java.lang.String BUNDLE_NAME = "<PACKAGE_NAME>"; //Ex: org.info.icf.flatfile private static final java.lang.String BUNDLE_VERSION = "1.0.0"; private static final java.lang.String CONNECTOR_NAME = "org.info.icf.flatfile.FlatFileConnector"; // Name of connector class i.e. the class implemting the connector SPI operations public ConnectorFacade getFacade() throws IOException { ConnectorInfoManagerFactory fact = ConnectorInfoManagerFactory .getInstance(); File bundleDirectory = new File("<BUNDLE_LOCATION>"); //Ex: /usr/oracle/connector_bundles/ URL url = IOUtil.makeURL(bundleDirectory, "org.info.icf.flatfile-1.0.0.jar"); ConnectorInfoManager manager = fact.getLocalManager(url); ConnectorKey key = new ConnectorKey(BUNDLE_NAME, BUNDLE_VERSION, CONNECTOR_NAME); ConnectorInfo info = manager.findConnectorInfo(key); // From the ConnectorInfo object, create the default APIConfiguration. APIConfiguration apiConfig = info.createDefaultAPIConfiguration(); // From the default APIConfiguration, retrieve the // ConfigurationProperties. ConfigurationProperties properties = apiConfig .getConfigurationProperties(); // Print out what the properties are (not necessary) List propertyNames = properties.getPropertyNames(); for (String propName : propertyNames) { ConfigurationProperty prop = properties.getProperty(propName); System.out.println("Property Name: " + prop.getName() + "\tProperty Type: " + prop.getType()); } properties .setPropertyValue("fileLocation", "/usr/oracle/accounts.csv"); // Set all of the ConfigurationProperties needed by the connector. // properties.setPropertyValue("host", FOOBAR_HOST); // properties.setPropertyValue("adminName", FOOBAR_ADMIN); // properties.setPropertyValue("adminPassword", FOOBAR_PASSWORD); // properties.setPropertyValue("useSSL", false); // Use the ConnectorFacadeFactory's newInstance() method to get a new // connector. ConnectorFacade connFacade = ConnectorFacadeFactory.getInstance() .newInstance(apiConfig); // Make sure we have set up the Configuration properly connFacade.validate(); return connFacade; } public static void main(String[] args) throws IOException { FlatFile file = new FlatFile(); ConnectorFacade cfac = file.getFacade(); Set attrSet = new HashSet(); attrSet.add(AttributeBuilder.build(Name.NAME, "Test01")); attrSet.add(AttributeBuilder.build("FIRST_NAME", "Test_First")); attrSet.add(AttributeBuilder.build("LAST_NAME", "Test_Last")); //Create Uid uid = cfac.create(ObjectClass.ACCOUNT, attrSet, null); //Delete Uid uidP = new Uid("Test01"); cfac.delete(ObjectClass.ACCOUNT, uidP, null); } }

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Building an ASP.Net 4.5 Web forms application - part 4

- by nikolaosk

?his is the fourth post in a series of posts on how to design and implement an ASP.Net 4.5 Web Forms store that sells posters on line.There are 3 more posts in this series of posts.Please make sure you read them first.You can find the first post here. You can find the second post here. You can find the third post here. In this new post we will build on the previous posts and we will demonstrate how to display the posters per category.We will add a ListView control on the PosterList.aspx and will bind data from the database. We will use the various templates.Then we will write code in the PosterList.aspx.cs to fetch data from the database.1) Launch Visual Studio and open your solution where your project lives2) Open the PosterList.aspx page. We will add some markup in this page. Have a look at the code below <section class="posters-featured"> <ul> <asp:ListView ID="posterList" runat="server" DataKeyNames="PosterID" GroupItemCount="3" ItemType="PostersOnLine.DAL.Poster" SelectMethod="GetPosters"> <EmptyDataTemplate> <table id="Table1" runat="server"> <tr> <td>We have no data.</td> </tr> </table> </EmptyDataTemplate> <EmptyItemTemplate> <td id="Td1" runat="server" /> </EmptyItemTemplate> <GroupTemplate> <tr ID="itemPlaceholderContainer" runat="server"> <td ID="itemPlaceholder" runat="server"></td> </tr> </GroupTemplate> <ItemTemplate> <td id="Td2" runat="server"> <table> <tr> <td> </td> <td> <a href="PosterDetails.aspx?posterID=<%#:Item.PosterID%>"> <img src="<%#:Item.PosterImgpath%>" width="100" height="75" border="1"/></a> </td> <td> <a href="PosterDetails.aspx?posterID=<%#:Item.PosterID%>"> <span class="PosterName"> <%#:Item.PosterName%> </span> </a> <br /> <span class="PosterPrice"> <b>Price: </b><%#:String.Format("{0:c}", Item.PosterPrice)%> </span> <br /> </td> </tr> </table> </td> </ItemTemplate> <LayoutTemplate> <table id="Table2" runat="server"> <tr id="Tr1" runat="server"> <td id="Td3" runat="server"> <table ID="groupPlaceholderContainer" runat="server"> <tr ID="groupPlaceholder" runat="server"></tr> </table> </td> </tr> <tr id="Tr2" runat="server"><td id="Td4" runat="server"></td></tr> </table> </LayoutTemplate> </asp:ListView> </ul> </section> 3) We have a ListView control on the page called PosterList. I set the ItemType property to the Poster class and then the SelectMethod to the GetPosters method. I will create this method later on. (ItemType="PostersOnLine.DAL.Poster" SelectMethod="GetPosters")Then in the code below I have the data-binding expression Item available and the control becomes strongly typed.So when the user clicks on the link of the poster's category the relevant information will be displayed (photo,name and price) <td> <a href="PosterDetails.aspx?posterID=<%#:Item.PosterID%>"> <img src="<%#:Item.PosterImgpath%>" width="100" height="75" border="1"/></a> </td>4) Now we need to write the simple method to populate the ListView control.It is called GetPosters method.The code follows public IQueryable<Poster> GetPosters([QueryString("id")] int? PosterCatID) { PosterContext ctx = new PosterContext(); IQueryable<Poster> query = ctx.Posters; if (PosterCatID.HasValue && PosterCatID > 0) { query = query.Where(p=>p.PosterCategoryID==PosterCatID); } return query; } This is a very simple method that returns information about posters related to the PosterCatID passed to it.I bind the value from the query string to the PosterCatID parameter at run time.This is all possible due to the QueryStringAttribute class that lives inside the System.Web.ModelBinding and gets the value of the query string variable id.5) I run my application and then click on the "Midfilders" link. Have a look at the picture below to see the results. In the Site.css file I added some new CSS rules to make everything more presentable. .posters-featured { width:840px; background-color:#efefef;}.posters-featured a:link, a:visited, a:active, a:hover { color: #000033; }.posters-featured a:hover { background-color: #85c465; } 6) I run the application again and this time I do not choose any category, I simply navigate to the PosterList.aspx page. I see all the posters since no query string was passed as a parameter.Have a look at the picture below ?ake sure you place breakpoints in the code so you can see what is really going on.In the next post I will show you how to display poster details.Hope it helps!!!

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Getting Started with Amazon Web Services in NetBeans IDE

- by Geertjan

When you need to connect to Amazon Web Services, NetBeans IDE gives you a nice start. You can drag and drop the "itemSearch" service into a Java source file and then various Amazon files are generated for you. From there, you need to do a little bit of work because the request to Amazon needs to be signed before it can be used. Here are some references and places that got me started: http://associates-amazon.s3.amazonaws.com/signed-requests/helper/index.html http://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSGettingStartedGuide/AWSCredentials.html https://affiliate-program.amazon.com/gp/flex/advertising/api/sign-in.html You definitely need to sign up to the Amazon Associates program and also register/create an Access Key ID, which will also get you a Secret Key, as well. Here's a simple Main class that I created that hooks into the generated RestConnection/RestResponse code created by NetBeans IDE: public static void main(String[] args) { try { String searchIndex = "Books"; String keywords = "Romeo and Juliet"; RestResponse result = AmazonAssociatesService.itemSearch(searchIndex, keywords); String dataAsString = result.getDataAsString(); int start = dataAsString.indexOf("<Author>")+8; int end = dataAsString.indexOf("</Author>"); System.out.println(dataAsString.substring(start,end)); } catch (Exception ex) { ex.printStackTrace(); }} Then I deleted the generated properties file and the authenticator and changed the generated AmazonAssociatesService.java file to the following: public class AmazonAssociatesService { private static void sleep(long millis) { try { Thread.sleep(millis); } catch (Throwable th) { } } public static RestResponse itemSearch(String searchIndex, String keywords) throws IOException { SignedRequestsHelper helper; RestConnection conn = null; Map queryMap = new HashMap(); queryMap.put("Service", "AWSECommerceService"); queryMap.put("AssociateTag", "myAssociateTag"); queryMap.put("AWSAccessKeyId", "myAccessKeyId"); queryMap.put("Operation", "ItemSearch"); queryMap.put("SearchIndex", searchIndex); queryMap.put("Keywords", keywords); try { helper = SignedRequestsHelper.getInstance( "ecs.amazonaws.com", "myAccessKeyId", "mySecretKey"); String sign = helper.sign(queryMap); conn = new RestConnection(sign); } catch (IllegalArgumentException | UnsupportedEncodingException | NoSuchAlgorithmException | InvalidKeyException ex) { } sleep(1000); return conn.get(null); }} Finally, I copied this class into my application, which you can see is referred to above: http://code.google.com/p/amazon-product-advertising-api-sample/source/browse/src/com/amazon/advertising/api/sample/SignedRequestsHelper.java Here's the completed app, mostly generated via the drag/drop shown at the start, but slightly edited as shown above: That's all, now everything works as you'd expect.

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Register Game Object Components in Game Subsystems? (Component-based Game Object design)

- by topright

I'm creating a component-based game object system. Some tips: GameObject is simply a list of Components. There are GameSubsystems. For example, rendering, physics etc. Each GameSubsystem contains pointers to some of Components. GameSubsystem is a very powerful and flexible abstraction: it represents any slice (or aspect) of the game world. There is a need in a mechanism of registering Components in GameSubsystems (when GameObject is created and composed). There are 4 approaches: 1: Chain of responsibility pattern. Every Component is offered to every GameSubsystem. GameSubsystem makes a decision which Components to register (and how to organize them). For example, GameSubsystemRender can register Renderable Components. pro. Components know nothing about how they are used. Low coupling. A. We can add new GameSubsystem. For example, let's add GameSubsystemTitles that registers all ComponentTitle and guarantees that every title is unique and provides interface to quering objects by title. Of course, ComponentTitle should not be rewrited or inherited in this case. B. We can reorganize existing GameSubsystems. For example, GameSubsystemAudio, GameSubsystemRender, GameSubsystemParticleEmmiter can be merged into GameSubsystemSpatial (to place all audio, emmiter, render Components in the same hierarchy and use parent-relative transforms). con. Every-to-every check. Very innefficient. con. Subsystems know about Components. 2: Each Subsystem searches for Components of specific types. pro. Better performance than in Approach 1. con. Subsystems still know about Components. 3: Component registers itself in GameSubsystem(s). We know at compile-time that there is a GameSubsystemRenderer, so let's ComponentImageRender will call something like GameSubsystemRenderer::register(ComponentRenderBase*). pro. Performance. No unnecessary checks as in Approach 1. con. Components are badly coupled with GameSubsystems. 4: Mediator pattern. GameState (that contains GameSubsystems) can implement registerComponent(Component*). pro. Components and GameSubystems know nothing about each other. con. In C++ it would look like ugly and slow typeid-switch. Questions: Which approach is better and mostly used in component-based design? What Practice says? Any suggestions about implementation of Approach 4? Thank you.

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Stumbling Through: Visual Studio 2010 (Part II)

I would now like to expand a little on what I stumbled through in part I of my Visual Studio 2010 post and touch on a few other features of VS 2010. Specifically, I want to generate some code based off of an Entity Framework model and tie it up to an actual data source. Im not going to take the easy way and tie to a SQL Server data source, though, I will tie it to an XML data file instead. Why? Well, why not? This is purely for learning, there are probably much better ways to get strongly-typed classes around XML but it will force us to go down a path less travelled and maybe learn a few things along the way. Once we get this XML data and the means to interact with it, I will revisit data binding to this data in a WPF form and see if I cant get reading, adding, deleting, and updating working smoothly with minimal code. To begin, I will use what was learned in the first part of this blog topic and draw out a data model for the MFL (My Football League) - I dont want the NFL to come down and sue me for using their name in this totally football-related article. The data model looks as follows, with Teams having Players, and Players having a position and statistics for each season they played: Note that when making the associations between these entities, I was given the option to create the foreign key but I only chose to select this option for the association between Player and Position. The reason for this is that I am picturing the XML that will contain this data to look somewhat like this: <MFL> <Position/> <Position/> <Position/> <Team> <Player> <Statistic/> </Player> </Team> </MFL> Statistic will be under its associated Player node, and Player will be under its associated Team node no need to have an Id to reference it if we know it will always fall under its parent. Position, however, is more of a lookup value that will not have any hierarchical relationship to the player. In fact, the Position data itself may be in a completely different xml file (something Id like to play around with), so in any case, a player will need to reference the position by its Id. So now that we have a simple data model laid out, I would like to generate two things based on it: A class for each entity with properties corresponding to each entity property An IO class with methods to get data for each entity, either all instances, by Id or by parent. Now my experience with code generation in the past has consisted of writing up little apps that use the code dom directly to regenerate code on demand (or using tools like CodeSmith). Surely, there has got to be a more fun way to do this given that we are using the Entity Framework which already has built-in code generation for SQL Server support. Lets start with that built-in stuff to give us a base to work off of. Right click anywhere in the canvas of our model and select Add Code Generation Item: So just adding that code item seemed to do quite a bit towards what I was intending: It apparently generated a class for each entity, but also a whole ton more. I mean a TON more. Way too much complicated code was generated now that code is likely to be a black box anyway so it shouldnt matter, but we need to understand how to make this work the way we want it to work, so lets get ready to do some stumbling through that text template (tt) file. When I open the .tt file that was generated, right off the bat I realize there is going to be trouble there is no color coding, no intellisense no nothing! That is going to make stumbling through more like groping blindly in the dark while handcuffed and hopping on one foot, which was one of the alternate titles I was considering for this blog. Thankfully, the community comes to my rescue and I wont have to cast my mind back to the glory days of coding in VI (look it up, kids). Using the Extension Manager (Available under the Tools menu), I did a quick search for tt editor in the Online Gallery and quickly found the Tangible T4 Editor: Downloading and installing this was a breeze, and after doing so I got some color coding and intellisense while editing the tt files. If you will be doing any customizing of tt files, I highly recommend installing this extension. Next, well see if that is enough help for us to tweak that tt file to do the kind of code generation that we wantDid you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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concurrency::index<N> from amp.h

- by Daniel Moth

Overview C++ AMP introduces a new template class index<N>, where N can be any value greater than zero, that represents a unique point in N-dimensional space, e.g. if N=2 then an index<2> object represents a point in 2-dimensional space. This class is essentially a coordinate vector of N integers representing a position in space relative to the origin of that space. It is ordered from most-significant to least-significant (so, if the 2-dimensional space is rows and columns, the first component represents the rows). The underlying type is a signed 32-bit integer, and component values can be negative. The rank field returns N. Creating an index The default parameterless constructor returns an index with each dimension set to zero, e.g. index<3> idx; //represents point (0,0,0) An index can also be created from another index through the copy constructor or assignment, e.g. index<3> idx2(idx); //or index<3> idx2 = idx; To create an index representing something other than 0, you call its constructor as per the following 4-dimensional example: int temp[4] = {2,4,-2,0}; index<4> idx(temp); Note that there are convenience constructors (that don’t require an array argument) for creating index objects of rank 1, 2, and 3, since those are the most common dimensions used, e.g. index<1> idx(3); index<2> idx(3, 6); index<3> idx(3, 6, 12); Accessing the component values You can access each component using the familiar subscript operator, e.g. One-dimensional example: index<1> idx(4); int i = idx[0]; // i=4 Two-dimensional example: index<2> idx(4,5); int i = idx[0]; // i=4 int j = idx[1]; // j=5 Three-dimensional example: index<3> idx(4,5,6); int i = idx[0]; // i=4 int j = idx[1]; // j=5 int k = idx[2]; // k=6 Basic operations Once you have your multi-dimensional point represented in the index, you can now treat it as a single entity, including performing common operations between it and an integer (through operator overloading): -- (pre- and post- decrement), ++ (pre- and post- increment), %=, *=, /=, +=, -=,%, *, /, +, -. There are also operator overloads for operations between index objects, i.e. ==, !=, +=, -=, +, –. Here is an example (where no assertions are broken): index<2> idx_a; index<2> idx_b(0, 0); index<2> idx_c(6, 9); _ASSERT(idx_a.rank == 2); _ASSERT(idx_a == idx_b); _ASSERT(idx_a != idx_c); idx_a += 5; idx_a[1] += 3; idx_a++; _ASSERT(idx_a != idx_b); _ASSERT(idx_a == idx_c); idx_b = idx_b + 10; idx_b -= index<2>(4, 1); _ASSERT(idx_a == idx_b); Usage You'll most commonly use index<N> objects to index into data types that we'll cover in future posts (namely array and array_view). Also when we look at the new parallel_for_each function we'll see that an index<N> object is the single parameter to the lambda, representing the (multi-dimensional) thread index… In the next post we'll go beyond being able to represent an N-dimensional point in space, and we'll see how to define the N-dimensional space itself through the extent<N> class. Comments about this post by Daniel Moth welcome at the original blog.

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Need help identifing what resources (eg. In MIT OpenCourseWare) can help me prepare for a test [closed]

- by jiewmeng

I am entering uni soon. I can sit for a placement test to see if I elegible for exemptions. The details are http://www.comp.nus.edu.sg/undergraduates/TestScope11_12.html Or CS2100 Computer Organisation (please click title) The objective of this module is to familiarise students with the fundamentals of computing devices. Through this module students will understand the basics of data representation, and how the various parts of a computer work, separately and with each other. This allows students to understand the issues in computing devices, and how these issues affect the implementation of solutions. Topics covered include data representation systems, combinational and sequential circuit design techniques, assembly language, processor execution cycles, pipelining, memory hierarchy and input/output systems. Recommended Textbooks Digital Design: Principles and Practices [DDPP] by John F. Wakerly, Prentice-Hall. ISBN 0-13-324500-4. Computer Organizations and Design (The hardware/software interface) by David A. Patterson and John L. Hennessy. CS2105 Introduction to Computer Networks (please click title) This course aims to provide a broad introduction to computer networks and some appreciations of network application programming. It covers a range of topics including basic data communication and computer network concepts, protocols, networked computing concepts and principles, network applications development and network security. The emphasis of teaching is on the working principles and application of computer networks. As an integral part of the course, tutorials and practical assignments enforcing learning will also be given. These assignments provide an early exposure in network application programming and they should be able to complete by using personal computers and school's network facilities. Topics included: An overview of computer networks and the Internet Basic data communications Application layer Transport layer Network layer and routing Link layer and local area networks Recommended Textbook James F. Kurose & Keith W. Ross, Computer networking: A top-down approach featuring internet, Addison Wesley, 2001 I am wondering what resources eg. MIT OpenCourseWare or other universities resources are available to help he perpare for these particular modubles. I am thinking does the Networking one look like CCNA? The computer oragization. Its like electronics, assembly etc? I learnt some electronics in Poly but looking at the sample papers, uni looks very different... I have about 1 month to prepare if I want any chance of exempting from these modules :) any help?

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