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• Windows Azure – Write, Run or Use Software

  - by BuckWoody

  Windows Azure is a platform that has you covered, whether you need to write software, run software that is already written, or Install and use “canned” software whether you or someone else wrote it. Like any platform, it’s a set of tools you can use where it makes sense to solve a problem. The primary location for Windows Azure information is located at http://windowsazure.com. You can find everything there from the development kits for writing software to pricing, licensing and tutorials on all of that. I have a few links here for learning to use Windows Azure – although it’s best if you focus not on the tools, but what you want to solve. I’ve got it broken down here into various sections, so you can quickly locate things you want to know. I’ll include resources here from Microsoft and elsewhere – I use these same resources in the Architectural Design Sessions (ADS) I do with my clients worldwide. Write Software Also called “Platform as a Service” (PaaS), Windows Azure has lots of components you can use together or separately that allow you to write software in .NET or various Open Source languages to work completely online, or in partnership with code you have on-premises or both – even if you’re using other cloud providers. Keep in mind that all of the features you see here can be used together, or independently. For instance, you might only use a Web Site, or use Storage, but you can use both together. You can access all of these components through standard REST API calls, or using our Software Development Kit’s API’s, which are a lot easier. In any case, you simply use Visual Studio, Eclipse, Cloud9 IDE, or even a text editor to write your code from a Mac, PC or Linux.  Components you can use: Azure Web Sites: Windows Azure Web Sites allow you to quickly write an deploy websites, without setting a Virtual Machine, installing a web server or configuring complex settings. They work alone, with other Windows Azure Web Sites, or with other parts of Windows Azure. Web and Worker Roles: Windows Azure Web Roles give you a full stateless computing instance with Internet Information Services (IIS) installed and configured. Windows Azure Worker Roles give you a full stateless computing instance without Information Services (IIS) installed, often used in a "Services" mode. Scale-out is achieved either manually or programmatically under your control. Storage: Windows Azure Storage types include Blobs to store raw binary data, Tables to use key/value pair data (like NoSQL data structures), Queues that allow interaction between stateless roles, and a relational SQL Server database. Other Services: Windows Azure has many other services such as a security mechanism, a Cache (memcacheD compliant), a Service Bus, a Traffic Manager and more. Once again, these features can be used with a Windows Azure project, or alone based on your needs. Various Languages: Windows Azure supports the .NET stack of languages, as well as many Open-Source languages like Java, Python, PHP, Ruby, NodeJS, C++ and more.   Use Software Also called “Software as a Service” (SaaS) this often means consumer or business-level software like Hotmail or Office 365. In other words, you simply log on, use the software, and log off – there’s nothing to install, and little to even configure. For the Information Technology professional, however, It’s not quite the same. We want software that provides services, but in a platform. That means we want things like Hadoop or other software we don’t want to have to install and configure.  Components you can use: Kits: Various software “kits” or packages are supported with just a few clicks, such as Umbraco, Wordpress, and others. Windows Azure Media Services: Windows Azure Media Services is a suite of services that allows you to upload media for encoding, processing and even streaming – or even one or more of those functions. We can add DRM and even commercials to your media if you like. Windows Azure Media Services is used to stream large events all the way down to small training videos. High Performance Computing and “Big Data”: Windows Azure allows you to scale to huge workloads using a few clicks to deploy Hadoop Clusters or the High Performance Computing (HPC) nodes, accepting HPC Jobs, Pig and Hive Jobs, and even interfacing with Microsoft Excel. Windows Azure Marketplace: Windows Azure Marketplace offers data and programs you can quickly implement and use – some free, some for-fee.   Run Software Also known as “Infrastructure as a Service” (IaaS), this offering allows you to build or simply choose a Virtual Machine to run server-based software.  Components you can use: Persistent Virtual Machines: You can choose to install Windows Server, Windows Server with Active Directory, with SQL Server, or even SharePoint from a pre-configured gallery. You can configure your own server images with standard Hyper-V technology and load them yourselves – and even bring them back when you’re done. As a new offering, we also even allow you to select various distributions of Linux – a first for Microsoft. Windows Azure Connect: You can connect your on-premises networks to Windows Azure Instances. Storage: Windows Azure Storage can be used as a remote backup, a hybrid storage location and more using software or even hardware appliances.   Decision Matrix With all of these options, you can use Windows Azure to solve just about any computing problem. It’s often hard to know when to use something on-premises, in the cloud, and what kind of service to use. I’ve used a decision matrix in the last couple of years to take a particular problem and choose the proper technology to solve it. It’s all about options – there is no “silver bullet”, whether that’s Windows Azure or any other set of functions. I take the problem, decide which particular component I want to own and control – and choose the column that has that box darkened. For instance, if I have to control the wiring for a solution (a requirement in some military and government installations), that means the “Networking” component needs to be dark, and so I select the “On Premises” column for that particular solution. If I just need the solution provided and I want no control at all, I can look as “Software as a Service” solutions. Security, Pricing, and Other Info  Security: Security is one of the first questions you should ask in any distributed computing environment. We have certification info, coding guidelines and more, even a general “Request for Information” RFI Response already created for you.   Pricing: Are there licenses? How much does this cost? Is there a way to estimate the costs in this new environment? New Features: Many new features were added to Windows Azure - a good roundup of those changes can be found here. Support: Software Support on Virtual Machines, general support.    

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• How to maintain encapsulation with composition in C++?

  - by iFreilicht

  I am designing a class Master that is composed from multiple other classes, A, Base, C and D. These four classes have absolutely no use outside of Master and are meant to split up its functionality into manageable and logically divided packages. They also provide extensible functionality as in the case of Base, which can be inherited from by clients. But, how do I maintain encapsulation of Master with this design? So far, I've got two approaches, which are both far from perfect: 1. Replicate all accessors: Just write accessor-methods for all accessor-methods of all classes that Master is composed of. This leads to perfect encapsulation, because no implementation detail of Master is visible, but is extremely tedious and makes the class definition monstrous, which is exactly what the composition should prevent. Also, adding functionality to one of the composees (is that even a word?) would require to re-write all those methods in Master. An additional problem is that inheritors of Base could only alter, but not add functionality. 2. Use non-assignable, non-copyable member-accessors: Having a class accessor<T> that can not be copied, moved or assigned to, but overrides the operator-> to access an underlying shared_ptr, so that calls like Master->A()->niceFunction(); are made possible. My problem with this is that it kind of breaks encapsulation as I would now be unable to change my implementation of Master to use a different class for the functionality of niceFunction(). Still, it is the closest I've gotten without using the ugly first approach. It also fixes the inheritance issue quite nicely. A small side question would be if such a class already existed in std or boost. EDIT: Wall of code I will now post the code of the header files of the classes discussed. It may be a bit hard to understand, but I'll give my best in explaining all of it. 1. GameTree.h The foundation of it all. This basically is a doubly-linked tree, holding GameObject-instances, which we'll later get to. It also has it's own custom iterator GTIterator, but I left that out for brevity. WResult is an enum with the values SUCCESS and FAILED, but it's not really important. class GameTree { public: //Static methods for the root. Only one root is allowed to exist at a time! static void ConstructRoot(seed_type seed, unsigned int depth); inline static bool rootExists(){ return static_cast<bool>(rootObject_); } inline static weak_ptr<GameTree> root(){ return rootObject_; } //delta is in ms, this is used for velocity, collision and such void tick(unsigned int delta); //Interaction with the tree inline weak_ptr<GameTree> parent() const { return parent_; } inline unsigned int numChildren() const{ return static_cast<unsigned int>(children_.size()); } weak_ptr<GameTree> getChild(unsigned int index) const; template<typename GOType> weak_ptr<GameTree> addChild(seed_type seed, unsigned int depth = 9001){ GOType object{ new GOType(seed) }; return addChildObject(unique_ptr<GameTree>(new GameTree(std::move(object), depth))); } WResult moveTo(weak_ptr<GameTree> newParent); WResult erase(); //Iterators for for( : ) loop GTIterator& begin(){ return *(beginIter_ = std::move(make_unique<GTIterator>(children_.begin()))); } GTIterator& end(){ return *(endIter_ = std::move(make_unique<GTIterator>(children_.end()))); } //unloading should be used when objects are far away WResult unloadChildren(unsigned int newDepth = 0); WResult loadChildren(unsigned int newDepth = 1); inline const RenderObject& renderObject() const{ return gameObject_->renderObject(); } //Getter for the underlying GameObject (I have not tested the template version) weak_ptr<GameObject> gameObject(){ return gameObject_; } template<typename GOType> weak_ptr<GOType> gameObject(){ return dynamic_cast<weak_ptr<GOType>>(gameObject_); } weak_ptr<PhysicsObject> physicsObject() { return gameObject_->physicsObject(); } private: GameTree(const GameTree&); //copying is only allowed internally GameTree(shared_ptr<GameObject> object, unsigned int depth = 9001); //pointer to root static shared_ptr<GameTree> rootObject_; //internal management of a child weak_ptr<GameTree> addChildObject(shared_ptr<GameTree>); WResult removeChild(unsigned int index); //private members shared_ptr<GameObject> gameObject_; shared_ptr<GTIterator> beginIter_; shared_ptr<GTIterator> endIter_; //tree stuff vector<shared_ptr<GameTree>> children_; weak_ptr<GameTree> parent_; unsigned int selfIndex_; //used for deletion, this isn't necessary void initChildren(unsigned int depth); //constructs children }; 2. GameObject.h This is a bit hard to grasp, but GameObject basically works like this: When constructing a GameObject, you construct its basic attributes and a CResult-instance, which contains a vector<unique_ptr<Construction>>. The Construction-struct contains all information that is needed to construct a GameObject, which is a seed and a function-object that is applied at construction by a factory. This enables dynamic loading and unloading of GameObjects as done by GameTree. It also means that you have to define that factory if you inherit GameObject. This inheritance is also the reason why GameTree has a template-function gameObject<GOType>. GameObject can contain a RenderObject and a PhysicsObject, which we'll later get to. Anyway, here's the code. class GameObject; typedef unsigned long seed_type; //this declaration magic means that all GameObjectFactorys inherit from GameObjectFactory<GameObject> template<typename GOType> struct GameObjectFactory; template<> struct GameObjectFactory<GameObject>{ virtual unique_ptr<GameObject> construct(seed_type seed) const = 0; }; template<typename GOType> struct GameObjectFactory : GameObjectFactory<GameObject>{ GameObjectFactory() : GameObjectFactory<GameObject>(){} unique_ptr<GameObject> construct(seed_type seed) const{ return unique_ptr<GOType>(new GOType(seed)); } }; //same as with the factories. this is important for storing them in vectors template<typename GOType> struct Construction; template<> struct Construction<GameObject>{ virtual unique_ptr<GameObject> construct() const = 0; }; template<typename GOType> struct Construction : Construction<GameObject>{ Construction(seed_type seed, function<void(GOType*)> func = [](GOType* null){}) : Construction<GameObject>(), seed_(seed), func_(func) {} unique_ptr<GameObject> construct() const{ unique_ptr<GameObject> gameObject{ GOType::factory.construct(seed_) }; func_(dynamic_cast<GOType*>(gameObject.get())); return std::move(gameObject); } seed_type seed_; function<void(GOType*)> func_; }; typedef struct CResult { CResult() : constructions{} {} CResult(CResult && o) : constructions(std::move(o.constructions)) {} CResult& operator= (CResult& other){ if (this != &other){ for (unique_ptr<Construction<GameObject>>& child : other.constructions){ constructions.push_back(std::move(child)); } } return *this; } template<typename GOType> void push_back(seed_type seed, function<void(GOType*)> func = [](GOType* null){}){ constructions.push_back(make_unique<Construction<GOType>>(seed, func)); } vector<unique_ptr<Construction<GameObject>>> constructions; } CResult; //finally, the GameObject class GameObject { public: GameObject(seed_type seed); GameObject(const GameObject&); virtual void tick(unsigned int delta); inline Matrix4f trafoMatrix(){ return physicsObject_->transformationMatrix(); } //getter inline seed_type seed() const{ return seed_; } inline CResult& properties(){ return properties_; } inline const RenderObject& renderObject() const{ return *renderObject_; } inline weak_ptr<PhysicsObject> physicsObject() { return physicsObject_; } protected: virtual CResult construct_(seed_type seed) = 0; CResult properties_; shared_ptr<RenderObject> renderObject_; shared_ptr<PhysicsObject> physicsObject_; seed_type seed_; }; 3. PhysicsObject That's a bit easier. It is responsible for position, velocity and acceleration. It will also handle collisions in the future. It contains three Transformation objects, two of which are optional. I'm not going to include the accessors on the PhysicsObject class because I tried my first approach on it and it's just pure madness (way over 30 functions). Also missing: the named constructors that construct PhysicsObjects with different behaviour. class Transformation{ Vector3f translation_; Vector3f rotation_; Vector3f scaling_; public: Transformation() : translation_{ 0, 0, 0 }, rotation_{ 0, 0, 0 }, scaling_{ 1, 1, 1 } {}; Transformation(Vector3f translation, Vector3f rotation, Vector3f scaling); inline Vector3f translation(){ return translation_; } inline void translation(float x, float y, float z){ translation(Vector3f(x, y, z)); } inline void translation(Vector3f newTranslation){ translation_ = newTranslation; } inline void translate(float x, float y, float z){ translate(Vector3f(x, y, z)); } inline void translate(Vector3f summand){ translation_ += summand; } inline Vector3f rotation(){ return rotation_; } inline void rotation(float pitch, float yaw, float roll){ rotation(Vector3f(pitch, yaw, roll)); } inline void rotation(Vector3f newRotation){ rotation_ = newRotation; } inline void rotate(float pitch, float yaw, float roll){ rotate(Vector3f(pitch, yaw, roll)); } inline void rotate(Vector3f summand){ rotation_ += summand; } inline Vector3f scaling(){ return scaling_; } inline void scaling(float x, float y, float z){ scaling(Vector3f(x, y, z)); } inline void scaling(Vector3f newScaling){ scaling_ = newScaling; } inline void scale(float x, float y, float z){ scale(Vector3f(x, y, z)); } void scale(Vector3f factor){ scaling_(0) *= factor(0); scaling_(1) *= factor(1); scaling_(2) *= factor(2); } Matrix4f matrix(){ return WMatrix::Translation(translation_) * WMatrix::Rotation(rotation_) * WMatrix::Scale(scaling_); } }; class PhysicsObject; typedef void tickFunction(PhysicsObject& self, unsigned int delta); class PhysicsObject{ PhysicsObject(const Transformation& trafo) : transformation_(trafo), transformationVelocity_(nullptr), transformationAcceleration_(nullptr), tick_(nullptr) {} PhysicsObject(PhysicsObject&& other) : transformation_(other.transformation_), transformationVelocity_(std::move(other.transformationVelocity_)), transformationAcceleration_(std::move(other.transformationAcceleration_)), tick_(other.tick_) {} Transformation transformation_; unique_ptr<Transformation> transformationVelocity_; unique_ptr<Transformation> transformationAcceleration_; tickFunction* tick_; public: void tick(unsigned int delta){ tick_ ? tick_(*this, delta) : 0; } inline Matrix4f transformationMatrix(){ return transformation_.matrix(); } } 4. RenderObject RenderObject is a base class for different types of things that could be rendered, i.e. Meshes, Light Sources or Sprites. DISCLAIMER: I did not write this code, I'm working on this project with someone else. class RenderObject { public: RenderObject(float renderDistance); virtual ~RenderObject(); float renderDistance() const { return renderDistance_; } void setRenderDistance(float rD) { renderDistance_ = rD; } protected: float renderDistance_; }; struct NullRenderObject : public RenderObject{ NullRenderObject() : RenderObject(0.f){}; }; class Light : public RenderObject{ public: Light() : RenderObject(30.f){}; }; class Mesh : public RenderObject{ public: Mesh(unsigned int seed) : RenderObject(20.f) { meshID_ = 0; textureID_ = 0; if (seed == 1) meshID_ = Model::getMeshID("EM-208_heavy"); else meshID_ = Model::getMeshID("cube"); }; unsigned int getMeshID() const { return meshID_; } unsigned int getTextureID() const { return textureID_; } private: unsigned int meshID_; unsigned int textureID_; }; I guess this shows my issue quite nicely: You see a few accessors in GameObject which return weak_ptrs to access members of members, but that is not really what I want. Also please keep in mind that this is NOT, by any means, finished or production code! It is merely a prototype and there may be inconsistencies, unnecessary public parts of classes and such.

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• Tips for XNA WP7 Developers

  - by Michael B. McLaughlin

  There are several things any XNA developer should know/consider when coming to the Windows Phone 7 platform. This post assumes you are familiar with the XNA Framework and with the changes between XNA 3.1 and XNA 4.0. It’s not exhaustive; it’s simply a list of things I’ve gathered over time. I may come back and add to it over time, and I’m happy to add anything anyone else has experienced or learned as well. Display · The screen is either 800x480 or 480x800. · But you aren’t required to use only those resolutions. · The hardware scaler on the phone will scale up from 240x240. · One dimension will be capped at 800 and the other at 480; which depends on your code, but you cannot have, e.g., an 800x600 back buffer – that will be created as 800x480. · The hardware scaler will not normally change aspect ratio, though, so no unintended stretching. · Any dimension (width, height, or both) below 240 will be adjusted to 240 (without any aspect ratio adjustment such that, e.g. 200x240 will be treated as 240x240). · Dimensions below 240 will be honored in terms of calculating whether to use portrait or landscape. · If dimensions are exactly equal or if height is greater than width then game will be in portrait. · If width is greater than height, the game will be in landscape. · Landscape games will automatically flip if the user turns the phone 180°; no code required. · Default landscape is top = left. In other words a user holding a phone who starts a landscape game will see the first image presented so that the “top” of the screen is along the right edge of his/her phone, such that the natural behavior would be to turn the phone 90° so that the top of the phone will be held in the user’s left hand and the bottom would be held in the user’s right hand. · The status bar (where the clock, battery power, etc., are found) is hidden when the Game-derived class sets GraphicsDeviceManager.IsFullScreen = true. It is shown when IsFullScreen = false. The default value is false (i.e. the status bar is shown). · You should have a good reason for hiding the status bar. Users find it helpful to know what time it is, how much charge their battery has left, and whether or not their phone is in service range. This is especially true for casual games that you expect someone to play for a few minutes at a time, e.g. while waiting for some event to start, for a phone call to come in, or for a train, bus, or subway to arrive. · In portrait mode, the status bar occupies 32 pixels of space. This means that a game with a back buffer of 480x800 will be scaled down to occupy approximately 461x768 screen pixels. Setting the back buffer to 480x768 (or some resolution with the same 0.625 aspect ratio) will avoid this scaling. · In landscape mode, the status bar occupies 72 pixels of space. This means that a game with a back buffer of 800x480 will be scaled down to occupy approximately 728x437 screen pixels. Setting the back buffer to 728x480 (or some resolution with the same 1.51666667 aspect ratio) will avoid this scaling. Input · Touch input is scaled with screen size. · So if your back buffer is 600x360, a tap in the bottom right corner will come in as (599,359). You don’t need to do anything special to get this automatic scaling of touch behavior. · If you do not use full area of the screen, any touch input outside the area you use will still register as a touch input. For example, if you set a portrait resolution of 240x240, it would be scaled up to occupy a 480x480 area, centered in the screen. If you touch anywhere above this area, you will get a touch input of (X,0) where X is a number from 0 to 239 (in accordance with your 240 pixel wide back buffer). Any touch below this area will give a touch input of (X,239). · If you keep the status bar visible, touches within its area will not be passed to your game. · In general, a screen measurement is the diagonal. So a 3.5” screen is 3.5” long from the bottom right corner to the top left corner. With an aspect ratio of 0.6 (480/800 = 0.6), this means that a phone with a 3.5” screen is only approximately 1.8” wide by 3” tall. So there are approximately 267 pixels in an inch on a 3.5” screen. · Again, this time in metric! 3.5 inches is approximately 8.89 cm. So an 8.89 cm screen is 8.89 cm long from the bottom right corner to the top left corner. With an aspect ratio of 0.6, this means that a phone with an 8.89 cm screen is only approximately 4.57 cm wide by 7.62 cm tall. So there are approximately 105 pixels in a centimeter on an 8.89 cm screen. · Think about the size of your finger tip. If you do not have large hands, think about the size of the fingertip of someone with large hands. Consider that when you are sizing your touch input. Especially consider that when you are spacing two touch targets near one another. You need to judge it for yourself, but items that are next to each other and are each 100x100 should be fine when it comes to selecting items individually. Smaller targets than that are ok provided that you leave space between them. · You want your users to have a pleasant experience. Making touch controls too small or too close to one another will make them nervous about whether they will touch the right target. Take this into account when you plan out your game initially. If possible, do some quick size mockups on an actual phone using colored rectangles that you position and size where you plan to have your game controls. Adjust as necessary. · People do not have transparent hands! Nor are their hands the size of a mouse pointer icon. Consider leaving a dedicated space for input rather than forcing the user to cover up to one-third of the screen with a finger just to play the game. · Another benefit of designing your controls to use a dedicated area is that you’re less likely to have players moving their finger(s) so frantically that they accidentally hit the back button, start button, or search button (many phones have one or more of these on the screen itself – it’s easy to hit one by accident and really annoying if you hit, e.g., the search button and then quickly tap back only to find out that the game didn’t save your progress such that you just wasted all the time you spent playing). · People do not like doing somersaults in order to move something forward with accelerometer-based controls. Test your accelerometer-based controls extensively and get a lot of feedback. Very well-known games from noted publishers have created really bad accelerometer controls and been virtually unplayable as a result. Also be wary of exceptions and other possible failures that the documentation warns about. · When done properly, the accelerometer can add a nice touch to your game (see, e.g. ilomilo where the accelerometer was used to move the background; it added a nice touch without frustrating the user; I also think CarniVale does direct accelerometer controls very well). However, if done poorly, it will make your game an abomination unto the Marketplace. Days, weeks, perhaps even months of development time that you will never get back. I won’t name names; you can search the marketplace for games with terrible reviews and you’ll find them. Graphics · The maximum frame rate is 30 frames per second. This was set as a compromise between battery life and quality. · At least one model of phone is known to have a screen refresh rate that is between 59 and 60 hertz. Because of this, using a fixed time step with a target frame rate of 30 will cause a slight internal delay to build up as the framework is forced to wait slightly for the next refresh. Eventually the delay will get to the point where a draw is skipped in order to recover from the delay. (See Nick's comment below for clarification.) · To deal with that delay, you can either stay with a fixed time step and set the frame rate slightly lower or else you can go to a variable time step and make sure to adjust all of your update data (e.g. player movement distance) to take into account the elapsed time from the last update. A variable time step makes your update logic slightly more complicated but will avoid frame skips entirely. · Currently there are no custom shaders. This might change in the future (there is no hardware limitation preventing it; it simply wasn’t a feature that could be implemented in the time available before launch). · There are five built-in shaders. You can create a lot of nice effects with the built-in shaders. · There is more power on the CPU than there is on the GPU so things you might typically off-load to the GPU will instead make sense to do on the CPU side. · This is a phone. It is not a PC. It is not an Xbox 360. The emulator runs on a PC and uses the full power of your PC. It is very good for testing your code for bugs and doing early prototyping and layout. You should not use it to measure performance. Use actual phone hardware instead. · There are many phone models, each of which has slightly different performance levels for I/O, screen blitting, CPU performance, etc. Do not take your game right to the performance limit on your phone since for some other phones you might be crossing their limits and leaving players with a bad experience. Leave a cushion to account for hardware differences. · Smaller screened phones will have slightly more dots per inch (dpi). Larger screened phones will have slightly less. Either way, the dpi will be much higher than the typical 96 found on most computer screens. Make sure that whoever is doing art for your game takes this into account. · Screens are only required to have 16 bit color (65,536 colors). This is common among smart phones. Using gradients on a 16 bit display can produce an ugly artifact known as banding. Banding is when, rather than a smooth transition from one color to another, you instead see distinct lines. Be careful to avoid this when possible. Banding can be avoided through careful art creation. Its effects can be minimized and even unnoticeable when the texture in question is always moving. You should be careful not to rely on “looks good on my phone” since some phones do have 32-bit displays and thus you’ll find yourself wondering why you’re getting bad reviews that complain about the graphics. Avoid gradients; if you can’t, make sure they are 16-bit safe. Audio · Never rely on sounds as your sole signal to the player that something is happening in the game. They might have the sound off. They might be playing somewhere loud. Etc. · You have to provide controls to disable sound & music. These should be separate. · On at least one model of phone, the volume control API currently has no effect. Players can adjust sound with their hardware volume buttons, but in game selectors simply won’t work. As such, it may not be worth the effort of providing anything beyond on/off switches for sound and music. · MediaPlayer.GameHasControl will return true when a game is hooked up to a PC running Zune. When Zune is running, any attempts to do anything (beyond check GameHasControl) with MediaPlayer will cause an exception to be thrown. If this exception is thrown, catch it and disable music. Exceptions take time to propagate; you don’t want one popping up in every single run of your game’s Update method. · Remember that players can already be listening to music or using the FM radio. In this case GameHasControl will be false and you should handle this appropriately. You can, alternately, ask the player for permission to stop their current music and play your music instead, but the (current) requirement that you restore their music when done is very hard (if not impossible) to deal with. · You can still play sound effects even when the game doesn’t have control of the music, but don’t think this is a backdoor to playing music. Your game will fail certification if your “sound effect” seems to be more like music in scope and length.

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• .NET Code Evolution

  - by Alois Kraus

  Originally posted on: http://geekswithblogs.net/akraus1/archive/2013/07/24/153504.aspxAt my day job I do look at a lot of code written by other people. Most of the code is quite good and some is even a masterpiece. And there is also code which makes you think WTF… oh it was written by me. Hm not so bad after all. There are many excuses reasons for bad code. Most often it is time pressure followed by not enough ambition (who cares) or insufficient training. Normally I do care about code quality quite a lot which makes me a (perceived) slow worker who does write many tests and refines the code quite a lot because of the design deficiencies. Most of the deficiencies I do find by putting my design under stress while checking for invariants. It does also help a lot to step into the code with a debugger (sometimes also Windbg). I do this much more often when my tests are red. That way I do get a much better understanding what my code really does and not what I think it should be doing. This time I do want to show you how code can evolve over the years with different .NET Framework versions. Once there was  time where .NET 1.1 was new and many C++ programmers did switch over to get rid of not initialized pointers and memory leaks. There were also nice new data structures available such as the Hashtable which is fast lookup table with O(1) time complexity. All was good and much code was written since then. At 2005 a new version of the .NET Framework did arrive which did bring many new things like generics and new data structures. The “old” fashioned way of Hashtable were coming to an end and everyone used the new Dictionary<xx,xx> type instead which was type safe and faster because the object to type conversion (aka boxing) was no longer necessary. I think 95% of all Hashtables and dictionaries use string as key. Often it is convenient to ignore casing to make it easy to look up values which the user did enter. An often followed route is to convert the string to upper case before putting it into the Hashtable. Hashtable Table = new Hashtable(); void Add(string key, string value) { Table.Add(key.ToUpper(), value); } This is valid and working code but it has problems. First we can pass to the Hashtable a custom IEqualityComparer to do the string matching case insensitive. Second we can switch over to the now also old Dictionary type to become a little faster and we can keep the the original keys (not upper cased) in the dictionary. Dictionary<string, string> DictTable = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase); void AddDict(string key, string value) { DictTable.Add(key, value); } Many people do not user the other ctors of Dictionary because they do shy away from the overhead of writing their own comparer. They do not know that .NET has for strings already predefined comparers at hand which you can directly use. Today in the many core area we do use threads all over the place. Sometimes things break in subtle ways but most of the time it is sufficient to place a lock around the offender. Threading has become so mainstream that it may sound weird that in the year 2000 some guy got a huge incentive for the idea to reduce the time to process calibration data from 12 hours to 6 hours by using two threads on a dual core machine. Threading does make it easy to become faster at the expense of correctness. Correct and scalable multithreading can be arbitrarily hard to achieve depending on the problem you are trying to solve. Lets suppose we want to process millions of items with two threads and count the processed items processed by all threads. A typical beginners code might look like this: int Counter; void IJustLearnedToUseThreads() { var t1 = new Thread(ThreadWorkMethod); t1.Start(); var t2 = new Thread(ThreadWorkMethod); t2.Start(); t1.Join(); t2.Join(); if (Counter != 2 * Increments) throw new Exception("Hmm " + Counter + " != " + 2 * Increments); } const int Increments = 10 * 1000 * 1000; void ThreadWorkMethod() { for (int i = 0; i < Increments; i++) { Counter++; } } It does throw an exception with the message e.g. “Hmm 10.222.287 != 20.000.000” and does never finish. The code does fail because the assumption that Counter++ is an atomic operation is wrong. The ++ operator is just a shortcut for Counter = Counter + 1 This does involve reading the counter from a memory location into the CPU, incrementing value on the CPU and writing the new value back to the memory location. When we do look at the generated assembly code we will see only inc dword ptr [ecx+10h] which is only one instruction. Yes it is one instruction but it is not atomic. All modern CPUs have several layers of caches (L1,L2,L3) which try to hide the fact how slow actual main memory accesses are. Since cache is just another word for redundant copy it can happen that one CPU does read a value from main memory into the cache, modifies it and write it back to the main memory. The problem is that at least the L1 cache is not shared between CPUs so it can happen that one CPU does make changes to values which did change in meantime in the main memory. From the exception you can see we did increment the value 20 million times but half of the changes were lost because we did overwrite the already changed value from the other thread. This is a very common case and people do learn to protect their  data with proper locking.   void Intermediate() { var time = Stopwatch.StartNew(); Action acc = ThreadWorkMethod_Intermediate; var ar1 = acc.BeginInvoke(null, null); var ar2 = acc.BeginInvoke(null, null); ar1.AsyncWaitHandle.WaitOne(); ar2.AsyncWaitHandle.WaitOne(); if (Counter != 2 * Increments) throw new Exception(String.Format("Hmm {0:N0} != {1:N0}", Counter, 2 * Increments)); Console.WriteLine("Intermediate did take: {0:F1}s", time.Elapsed.TotalSeconds); } void ThreadWorkMethod_Intermediate() { for (int i = 0; i < Increments; i++) { lock (this) { Counter++; } } } This is better and does use the .NET Threadpool to get rid of manual thread management. It does give the expected result but it can result in deadlocks because you do lock on this. This is in general a bad idea since it can lead to deadlocks when other threads use your class instance as lock object. It is therefore recommended to create a private object as lock object to ensure that nobody else can lock your lock object. When you read more about threading you will read about lock free algorithms. They are nice and can improve performance quite a lot but you need to pay close attention to the CLR memory model. It does make quite weak guarantees in general but it can still work because your CPU architecture does give you more invariants than the CLR memory model. For a simple counter there is an easy lock free alternative present with the Interlocked class in .NET. As a general rule you should not try to write lock free algos since most likely you will fail to get it right on all CPU architectures. void Experienced() { var time = Stopwatch.StartNew(); Task t1 = Task.Factory.StartNew(ThreadWorkMethod_Experienced); Task t2 = Task.Factory.StartNew(ThreadWorkMethod_Experienced); t1.Wait(); t2.Wait(); if (Counter != 2 * Increments) throw new Exception(String.Format("Hmm {0:N0} != {1:N0}", Counter, 2 * Increments)); Console.WriteLine("Experienced did take: {0:F1}s", time.Elapsed.TotalSeconds); } void ThreadWorkMethod_Experienced() { for (int i = 0; i < Increments; i++) { Interlocked.Increment(ref Counter); } } Since time does move forward we do not use threads explicitly anymore but the much nicer Task abstraction which was introduced with .NET 4 at 2010. It is educational to look at the generated assembly code. The Interlocked.Increment method must be called which does wondrous things right? Lets see: lock inc dword ptr [eax] The first thing to note that there is no method call at all. Why? Because the JIT compiler does know very well about CPU intrinsic functions. Atomic operations which do lock the memory bus to prevent other processors to read stale values are such things. Second: This is the same increment call prefixed with a lock instruction. The only reason for the existence of the Interlocked class is that the JIT compiler can compile it to the matching CPU intrinsic functions which can not only increment by one but can also do an add, exchange and a combined compare and exchange operation. But be warned that the correct usage of its methods can be tricky. If you try to be clever and look a the generated IL code and try to reason about its efficiency you will fail. Only the generated machine code counts. Is this the best code we can write? Perhaps. It is nice and clean. But can we make it any faster? Lets see how good we are doing currently. Level Time in s IJustLearnedToUseThreads Flawed Code Intermediate 1,5 (lock) Experienced 0,3 (Interlocked.Increment) Master 0,1 (1,0 for int[2]) That lock free thing is really a nice thing. But if you read more about CPU cache, cache coherency, false sharing you can do even better. int[] Counters = new int[12]; // Cache line size is 64 bytes on my machine with an 8 way associative cache try for yourself e.g. 64 on more modern CPUs void Master() { var time = Stopwatch.StartNew(); Task t1 = Task.Factory.StartNew(ThreadWorkMethod_Master, 0); Task t2 = Task.Factory.StartNew(ThreadWorkMethod_Master, Counters.Length - 1); t1.Wait(); t2.Wait(); Counter = Counters[0] + Counters[Counters.Length - 1]; if (Counter != 2 * Increments) throw new Exception(String.Format("Hmm {0:N0} != {1:N0}", Counter, 2 * Increments)); Console.WriteLine("Master did take: {0:F1}s", time.Elapsed.TotalSeconds); } void ThreadWorkMethod_Master(object number) { int index = (int) number; for (int i = 0; i < Increments; i++) { Counters[index]++; } } The key insight here is to use for each core its own value. But if you simply use simply an integer array of two items, one for each core and add the items at the end you will be much slower than the lock free version (factor 3). Each CPU core has its own cache line size which is something in the range of 16-256 bytes. When you do access a value from one location the CPU does not only fetch one value from main memory but a complete cache line (e.g. 16 bytes). This means that you do not pay for the next 15 bytes when you access them. This can lead to dramatic performance improvements and non obvious code which is faster although it does have many more memory reads than another algorithm. So what have we done here? We have started with correct code but it was lacking knowledge how to use the .NET Base Class Libraries optimally. Then we did try to get fancy and used threads for the first time and failed. Our next try was better but it still had non obvious issues (lock object exposed to the outside). Knowledge has increased further and we have found a lock free version of our counter which is a nice and clean way which is a perfectly valid solution. The last example is only here to show you how you can get most out of threading by paying close attention to your used data structures and CPU cache coherency. Although we are working in a virtual execution environment in a high level language with automatic memory management it does pay off to know the details down to the assembly level. Only if you continue to learn and to dig deeper you can come up with solutions no one else was even considering. I have studied particle physics which does help at the digging deeper part. Have you ever tried to solve Quantum Chromodynamics equations? Compared to that the rest must be easy ;-). Although I am no longer working in the Science field I take pride in discovering non obvious things. This can be a very hard to find bug or a new way to restructure data to make something 10 times faster. Now I need to get some sleep ….

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• WPF TreeView databinding to hide/show expand/collapse icon

  - by Julian Lettner

  I implemented a WPF load-on-demand treeview like described in this (very good) article. In the mentioned solution a dummy element is used to preserve the expand + icon / treeview item behavior. The dummy item is replaced with real data, when the user clicks on the expander. I want to refine the model by adding a property public bool HasChildren { get { ... } } to my backing TreeNodeViewModel. Question: How can I bind this property to hide/show the expand icon (in XAML)? I am not able to find a suitable trigger/setter combination. (INotifyPropertyChanged is properly implemented.) Thanks for your time. Update 1: I want to use my property public bool HasChildren instead of using the dummy element. Determining whether or not an item has children is somewhat costly, but still much cheaper than fetching the children.

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• NHibernate, and odd "Session is Closed!" errors

  - by Sekhat

  Note: Now that I've typed this out, I have to apologize for the super long question, however, I think all the code and information presented here is in some way relevant. Okay, I'm getting odd "Session Is Closed" errors, at random points in my ASP.NET webforms application. Today, however, it's finally happening in the same place over and over again. I am near certain that nothing is disposing or closing the session in my code, as the bits of code that use are well contained away from all other code as you'll see below. I'm also using ninject as my IOC, which may / may not be important. Okay, so, First my SessionFactoryProvider and SessionProvider classes: SessionFactoryProvider public class SessionFactoryProvider : IDisposable { ISessionFactory sessionFactory; public ISessionFactory GetSessionFactory() { if (sessionFactory == null) sessionFactory = Fluently.Configure() .Database( MsSqlConfiguration.MsSql2005.ConnectionString(p => p.FromConnectionStringWithKey("QoiSqlConnection"))) .Mappings(m => m.FluentMappings.AddFromAssemblyOf<JobMapping>()) .BuildSessionFactory(); return sessionFactory; } public void Dispose() { if (sessionFactory != null) sessionFactory.Dispose(); } } SessionProvider public class SessionProvider : IDisposable { ISessionFactory sessionFactory; ISession session; public SessionProvider(SessionFactoryProvider sessionFactoryProvider) { this.sessionFactory = sessionFactoryProvider.GetSessionFactory(); } public ISession GetCurrentSession() { if (session == null) session = sessionFactory.OpenSession(); return session; } public void Dispose() { if (session != null) { session.Dispose(); } } } These two classes are wired up with Ninject as so: NHibernateModule public class NHibernateModule : StandardModule { public override void Load() { Bind<SessionFactoryProvider>().ToSelf().Using<SingletonBehavior>(); Bind<SessionProvider>().ToSelf().Using<OnePerRequestBehavior>(); } } and as far as I can tell work as expected. Now my BaseDao<T> class: BaseDao public class BaseDao<T> : IDao<T> where T : EntityBase { private SessionProvider sessionManager; protected ISession session { get { return sessionManager.GetCurrentSession(); } } public BaseDao(SessionProvider sessionManager) { this.sessionManager = sessionManager; } public T GetBy(int id) { return session.Get<T>(id); } public void Save(T item) { using (var transaction = session.BeginTransaction()) { session.SaveOrUpdate(item); transaction.Commit(); } } public void Delete(T item) { using (var transaction = session.BeginTransaction()) { session.Delete(item); transaction.Commit(); } } public IList<T> GetAll() { return session.CreateCriteria<T>().List<T>(); } public IQueryable<T> Query() { return session.Linq<T>(); } } Which is bound in Ninject like so: DaoModule public class DaoModule : StandardModule { public override void Load() { Bind(typeof(IDao<>)).To(typeof(BaseDao<>)) .Using<OnePerRequestBehavior>(); } } Now the web request that is causing this is when I'm saving an object, it didn't occur till I made some model changes today, however the changes to my model has not changed the data access code in anyway. Though it changed a few NHibernate mappings (I can post these too if anyone is interested) From as far as I can tell, BaseDao<SomeClass>.Get is called then BaseDao<SomeOtherClass>.Get is called then BaseDao<TypeImTryingToSave>.Save is called. it's the third call at the line in Save() using (var transaction = session.BeginTransaction()) that fails with "Session is Closed!" or rather the exception: Session is closed! Object name: 'ISession'. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.ObjectDisposedException: Session is closed! Object name: 'ISession'. And indeed following through on the Debugger shows the third time the session is requested from the SessionProvider it is indeed closed and not connected. I have verified that Dispose on my SessionFactoryProvider and on my SessionProvider are called at the end of the request and not before the Save call is made on my Dao. So now I'm a little stuck. A few things pop to mind. Am I doing anything obviously wrong? Does NHibernate ever close sessions without me asking to? Any workarounds or ideas on what I might do? Thanks in advance

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• ASPNET MVC - Why is ModelState.IsValid false "The x field is required" when that field does have a v

  - by JK

  I have a model like this: public PurchaseOrder { [Required] [StringLength(15)] public virtual string OrderNumber {get;set;} // etc. } When I submit an order from the view (using $.post, not input type=submit) it goes to my controller class: public class PurchaseOrderController { public JsonResult Save(PurchaseOrder order) { // TryUpdateModel(order); // commented out since modelstate.isvalid remains false anyway if (ModelState.IsValid) { // its never valid } } } ModelState.IsValid always returns false, with the error: "The Order Number field is required." But there is a value in this field (?? why) Why would it say "value is required" when it does have a value? Have I missed something? Is it because of the $.post instead of the submit? What can I do? This is what the debugger looks like:

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• ASP.Net Authentication with MVC2--how to integrate with DB?

  - by alchemical

  I'm trying to understand the authentication section sample project that opens in a new MVC2 project in VS2010. It essentially lets you register, login, etc. I looked through the code that implements this briefly, it looked fairly complicated. (10 tables, 40 sprocs, 10 views, 4 models, 1 model, 1 controller, etc.) Is it best to utilize this provided framework for authentication? If so, how would I integrate this with my own database models (which has user and role tables, etc.). Also, if I use their framework, are there any performance issues at higher traffic volumes (like SO for example), do I need to become responsible for maintaining the authentication DB as well in this case?

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• Android ListView: get data index of visible item

  - by Mayra

  I have an Android ListView created with a SimpleAdapter that has more items in it than fit in the screen. After the list has been scrolled, I need to get the position in the data model of the first visible item in the list. Basically I want a function like: listView.getChildAt(0).getPositionInDataModel(). Adapter has a few functions in it, like getItemId(position) that looked useful; however, the SimpleAdapter implementation just returns the passed in position, not a row id like I'd hoped. A brute force solution would be to get the View at index 0, and compare it to the view for each item in the adapter. However, there doesn't seem to be an easy way to get the view for a particular position from the adapter. Anyone have any thoughts?

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• Creating blob properties with Entity Framework 4?

  - by David Veeneman

  I am creating an EF4 model-first application with a WPF UI. One of the controls on my UI is a RichTextDocument, which outputs a WPF FlowDocument. I can either serialize the FlowDocument to a byte array, or extract its XAML markup as a string. I would prefer to use binary serialization, if I can. Here are my questions: If I serialize to a byte array, how do I specify an entity property as a byte array in the EDM Designer? If I extract a XAML markup string, can I specify that the EDM Designer create the corresponding database column as a nvarchar(max) column? As to the second question, I assume I could always manually edit the MyModel.edmx.sql file to change the data type from nvarchar(4000) to nvarchar(max) before executing it, but I would like to know if it can be done in the Designer. Thanks for your help.

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• Html.EditorFor, Html.DisplayFor not working on MVC1.0 -> MVC2.0 manual migration

  - by lawrence-chase

  Has anyone encountered this problem? I manually migrated a MVC1.0 application to MVC2.0 and everything so far seems to be working fine. Today I wanted to try out the Html.EditorFor helper and it doesn't render the template. I set it up the same way in a fresh MVC2.0 application and the template does render. Is there anything other (or specifically needed when mirgrating to activate this behavior) than throwing the partial view like DateTime.ascx into Views/Shared/EditorTemplates and using the helper methods to render the model objects? I'm stumped.

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• MetadataException: Unable to load the specified metadata resource

  - by J. Steen

  All of a sudden I keep getting a MetadataException on instantiating my generated ObjectContext class. The connectionstring in App.Config looks correct - hasn't changed since last it worked - and I've tried regenerating a new model (edmx-file) from the underlying database with no change. Anyone have any... ideas? Edit: I haven't changed any properties, I haven't changed the name of any output assemblies, I haven't tried to embed the EDMX in the assembly. I've merely waited 10 hours from leaving work until I got back. And then it wasn't working anymore. I've tried recreating the EDMX. I've tried recreating the project. I've even tried recreating the database, from scratch. No luck, whatsoever. I'm truly stumped.

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• Deployment Error: Silverlight 4.0 w/WCF RIA Services in ASP.NET MVC 2 App

  - by Dennis Ward

  I've got an MVC 2 App with an RIA Services link to a Silverlight Application. On my local machine, all is well, but when I deploy to Discount ASP servers, neither the MVC controller nor the WCF RIA services called from silverlight function: A silverlight datagrid gets a load error: System.ServiceModel.DomainServices.Client.DomainOperationException: Load operation failed for query... The remote server returned an error NotFound. In the MVC page where I had a simple table that worked prior to adding an EF model and DomainDataSource, I now get the error: Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information. This is very similar to an issue I had before, but after upgrading from the betas of WCF/Silverlight 4, but the fix I had added there doesn't seem to work any longer. The link for that issue is: SL4/MVC2/WCF RIA Services = Load Error I'm really struggling with deploying, and could use some help if anybody can shed any light on this. Thanks! Dennis

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• MVC repository pattern design decision

  - by bradjive

  I have an asp .net MVC application and recently started implementing the repository pattern with a service validation layer, much like this. I've been creating one repository/service for each model that I create. Is this overkill? Instead, should I create one repository/service for each logical business area that provides CRUD for many different models? To me, it seems like I'm either cluttering the project tree with many files or cluttering a class with many methods. 6 one way half dozen the other. Can you think of any good arguments either way?

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• Can not execute Sonar

  - by senzacionale

  my pom.xml <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>RCC</groupId> <artifactId>tmp</artifactId> <name>tmp</name> <version>1.0</version> <build> <sourceDirectory>C:\Projekti\KIS\Model\src </sourceDirectory> <outputDirectory>C:\Projekti\KIS\Model\classes</outputDirectory> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <configuration> <source>1.5</source> <target>1.5</target> <excludes> <exclude>**/*.*</exclude> </excludes> </configuration> </plugin> </plugins> </build> <properties> <sonar.dynamicAnalysis>false</sonar.dynamicAnalysis> </properties> </project> running sonnar C:\Projekti\Metrics>mvn sonar:sonar -e + Error stacktraces are turned on. [INFO] Scanning for projects... [INFO] Searching repository for plugin with prefix: 'sonar'. [INFO] ------------------------------------------------------------------------ [INFO] Building tmp [INFO] task-segment: [sonar:sonar] (aggregator-style) [INFO] ------------------------------------------------------------------------ [INFO] [sonar:sonar {execution: default-cli}] [INFO] Sonar host: http://localhost:9000 [INFO] Sonar version: 2.1.2 [INFO] [sonar-core:internal {execution: default-internal}] [INFO] ------------------------------------------------------------------------ [ERROR] BUILD ERROR [INFO] ------------------------------------------------------------------------ [INFO] Can not execute Sonar Embedded error: Can not analyze the project org.apache.derby.jdbc.ClientDriver [INFO] ------------------------------------------------------------------------ [INFO] Trace org.apache.maven.lifecycle.LifecycleExecutionException: Can not execute Sonar at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:719) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeStandaloneGoal(DefaultLifecycleExecutor.java:569) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(DefaultLifecycleExecutor.java:539) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHandleFailures(DefaultLifecycleExecutor.java:387) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegments(DefaultLifecycleExecutor.java:284) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:180) at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:328) at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:138) at org.apache.maven.cli.MavenCli.main(MavenCli.java:362) at org.apache.maven.cli.compat.CompatibleMain.main(CompatibleMain.java:60) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315) at org.codehaus.classworlds.Launcher.launch(Launcher.java:255) at org.codehaus.classworlds.Launcher.mainWithExitCode(Launcher.java:430) at org.codehaus.classworlds.Launcher.main(Launcher.java:375) Caused by: org.apache.maven.plugin.MojoExecutionException: Can not execute Sonar at org.codehaus.mojo.sonar.Bootstraper.executeMojo(Bootstraper.java:87) at org.codehaus.mojo.sonar.Bootstraper.start(Bootstraper.java:65) at org.codehaus.mojo.sonar.SonarMojo.execute(SonarMojo.java:117) at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPluginManager.java:490) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:694) ... 17 more Caused by: org.apache.maven.plugin.MojoExecutionException: Can not analyze the project at org.sonar.maven2.BatchMojo.executeBatch(BatchMojo.java:152) at org.sonar.maven2.BatchMojo.execute(BatchMojo.java:131) at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPluginManager.java:490) at org.codehaus.mojo.sonar.Bootstraper.executeMojo(Bootstraper.java:82) ... 21 more Caused by: org.picocontainer.PicoLifecycleException: PicoLifecycleException: method 'public void org.sonar.api.database.AbstractDatabaseConnector.start()', instance 'org.sonar.api.database.DriverDatabaseConnector@c87621, java.lang.RuntimeException: wrapper at org.picocontainer.monitors.NullComponentMonitor.lifecycleInvocationFailed(NullComponentMonitor.java:77) at org.picocontainer.lifecycle.ReflectionLifecycleStrategy.monitorAndThrowReflectionLifecycleException(ReflectionLifecycleStrategy.java:132) at org.picocontainer.lifecycle.ReflectionLifecycleStrategy.invokeMethod(ReflectionLifecycleStrategy.java:115) at org.picocontainer.lifecycle.ReflectionLifecycleStrategy.start(ReflectionLifecycleStrategy.java:89) at org.picocontainer.injectors.AbstractInjectionFactory$LifecycleAdapter.start(AbstractInjectionFactory.java:84) at org.picocontainer.behaviors.AbstractBehavior.start(AbstractBehavior.java:169) at org.picocontainer.behaviors.Stored$RealComponentLifecycle.start(Stored.java:132) at org.picocontainer.behaviors.Stored.start(Stored.java:110) at org.picocontainer.DefaultPicoContainer.potentiallyStartAdapter(DefaultPicoContainer.java:996) at org.picocontainer.DefaultPicoContainer.startAdapters(DefaultPicoContainer.java:989) at org.picocontainer.DefaultPicoContainer.start(DefaultPicoContainer.java:746) at org.sonar.batch.AggregatorBatch.execute(AggregatorBatch.java:84) at org.sonar.maven2.BatchMojo.executeBatch(BatchMojo.java:149) ... 24 more Caused by: java.lang.RuntimeException: wrapper at org.picocontainer.lifecycle.ReflectionLifecycleStrategy.monitorAndThrowReflectionLifecycleException(ReflectionLifecycleStrategy.java:130) ... 35 more Caused by: org.sonar.api.database.DatabaseException: Cannot open connection to database: SQL driver not found org.apache.derby.jdbc.ClientDriver at org.sonar.api.database.AbstractDatabaseConnector.testConnection(AbstractDatabaseConnector.java:182) at org.sonar.api.database.AbstractDatabaseConnector.start(AbstractDatabaseConnector.java:94) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.picocontainer.lifecycle.ReflectionLifecycleStrategy.invokeMethod(ReflectionLifecycleStrategy.java:110) ... 34 more Caused by: java.sql.SQLException: SQL driver not found org.apache.derby.jdbc.ClientDriver at org.sonar.api.database.DriverDatabaseConnector.getConnection(DriverDatabaseConnector.java:70) at org.sonar.api.database.AbstractDatabaseConnector.testConnection(AbstractDatabaseConnector.java:178) ... 40 more Caused by: java.lang.ClassNotFoundException: org.apache.derby.jdbc.ClientDriver at java.net.URLClassLoader$1.run(URLClassLoader.java:200) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:188) at java.lang.ClassLoader.loadClass(ClassLoader.java:306) at org.codehaus.classworlds.RealmClassLoader.loadClassDirect(RealmClassLoader.java:195) at org.codehaus.classworlds.DefaultClassRealm.loadClass(DefaultClassRealm.java:255) at org.codehaus.classworlds.DefaultClassRealm.loadClass(DefaultClassRealm.java:274) at org.codehaus.classworlds.RealmClassLoader.loadClass(RealmClassLoader.java:214) at java.lang.ClassLoader.loadClass(ClassLoader.java:251) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:164) at org.sonar.api.database.DriverDatabaseConnector.getConnection(DriverDatabaseConnector.java:68) ... 41 more [INFO] ------------------------------------------------------------------------ [INFO] Total time: 3 seconds [INFO] Finished at: Wed Jun 09 12:12:55 CEST 2010 [INFO] Final Memory: 12M/23M [INFO] ------------------------------------------------------------------------ any idea why not working Sonar with maven?

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• WCF "DataContext accessed after Dispose"

  - by David Ward

  I have an application with numerous WCF services that make use of LINQ-To-SQL as the data access model. I am having lots of problems with the "DataContext accessed after Dispose" exception. I understand what this exception is and that it is occurring because I have not "initialised" the data that is trying to be accessed. I've read many articles that suggest that I called ToList() on any arrays before the parent object is returned by the service. My issue is that I am getting this exception and I don't know where it is originating from and therefore I don't know what hasn't been initialised. Can anyone advise how best to identify the root cause? (I have used the MS Service Trace Viewer and this doesn't seem to give me any further information)

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• WPF Combobox textbox not updating when binding changes.

  - by WillH

  I have a WPF CombBox as follows: <ComboBox ItemsSource="{Binding Source={StaticResource myList}}" SelectedItem="{Binding Path=mySelectedItem}" /> The problem I have is that when the bound value changes, the selected value in the combobox's textbox does not update. (Note - the values in the combobox list do update). I am using MVVM so I can detect in the view model when the binding changes and call a property changed event and this is updating the combobox, but not the value displayed within the textbox. I think this could be done in the template of the combobox - somehow make the textbox be bound to the selecteditem of the combobox, or always update when it updates? I don't know how to do this though so any advice would be most appreciated.

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• What enterprise architecture tools support DoDAF 2.0?

  - by David Hunt

  What tools best support the DoD Architecture Framework (DoDAF) Version 2.0, including support for transfer of the architecture data in accordance with the DoDAF Meta Model (DM2) Physical Exchange Specification (PES)? My initial research found that MagicDraw and Casewise claim support for version 2.0; and several other tools have support for earlier (or unspecified) DoDAF/MoDAF versions including Sparx Enterprise Architect, Troux, IDS Scheer ARIS, Artisan Studio and Rational System Architect. Experiences with any enterprise architecture tools and DoDAF 2.0 would be appreciated. The immediate need is for Data and Information Viewpoint models (DIV-1, DIV-2/OV-7, DIV-3/SV-11), but models in the other Viewpoints will be developed. Thanks -

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• Django - How best to handle ValidationErrors after form.save(commit=False)

  - by orokusaki

  This is a fragment of my code from a view: if form.is_valid(): instance = form.save(commit=False) try: instance.account = request.account instance.full_clean() except ValidationError, e: # Do something with the errors here... I don't know what the best thing to do here is, but I certainly don't want to do it 180 times. This is an utter mess. Who would want to handle validation errors manually in every view. If you're not modifying the instance after save(commit=False), you don't have to worry about this, but what about in my case where every model has a foreign key to account which is set behind the scenes and hidden from the user? Any help is really appreciated.

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• How to implement paging for datagrid using LINQ to Entities in wpf?

  - by Levelbit

  I'm new in wpf. My main problem is to understand how DataGrid works with its datacontext. It would help me a lot because I don't know how to make a universal paging usercontrol for all my datagrids in the projects for different database tables. DataGrid converts received DataContext from object to some kind of list. How it is implemented. I tried to do some casting from object to IQueryable to generalize thinig because base class of every entity in the entity model is EntityObject class. But it doesen't work in runtime although I don't receive complains at design time.

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• Fluent NHibernate Map Enum as Lookup Table

  - by Jaimal Chohan

  I have the following (simplified) public enum Level { Bronze, Silver, Gold } public class Member { public virtual Level MembershipLevel { get; set; } } public class MemberMap : ClassMap<Member> { Map(x => x.MembershipLevel); } This creates a table with a column called MembershipLevel with the value as the Enum string value. What I want is for the entire Enum to be created as a lookup table, with the Membe table referencing this with the integer value as the FK. Also, I want to do this without bas***izing my model. Any ideas? [And I want time machine] [With 2 cup holders]

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• Knockout.js mapping plugin with require.js

  - by Ravi

  What is the standard way of loading mapping plugin in require.js ? Below is my config.js (require.js config file) require.config({ // Initialize the application with the main application file. deps:["app"], paths:{ // JavaScript folders. libs:"lib", plugins:"lib/plugin", templates:"../templates", // Libraries. jquery:"lib/jquery-1.7.2.min", underscore:"lib/lodash", text:'text', order:'order', knockout:"lib/knockout", knockoutmapping:"lib/plugin/knockout-mapping" }, shim:{ underscore:{ exports:'_' }, knockout:{ deps:["jquery"], exports:"knockout" } } } In my view model define(['knockout', 'knockoutmapping'], function(ko, mapping) { } However, mapping is not bound to ko.mapping. Any pointers/suggestions would be appreciated. Thanks, Ravi

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• using grails and google app engine to store image as blob and the view dynamically

  - by mswallace

  I am trying to dynamically display an image that I am storing in the google datastore as a Blob. I am not getting any errors but I am getting a broken image on the page that I view. Any help would be awesome! I have the following code in my grails app domain class has the following @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) Long id @Persistent String siteName @Persistent String url @Persistent Blob img @Persistent String yourName @Persistent String yourURL @Persistent Date date static constraints = { id( visible:false) } My save method in the controller has this def save = { params.img = new Blob(params.imgfile.getBytes()) def siteInfoInstance = new SiteInfo(params) if(!siteInfoInstance.hasErrors() ) { try{ persistenceManager.makePersistent(siteInfoInstance) } finally{ flash.message = "SiteInfo ${siteInfoInstance.id} created" redirect(action:show,id:siteInfoInstance.id) } } render(view:'create',model:[siteInfoInstance:siteInfoInstance]) } My view has the following <img src="${createLink(controller:'siteInfoController', action:'showImage', id:fieldValue(bean:siteInfoInstance, field:'id'))}"></img> and the method in my controller that it is calling to display a link to the image looks like this def showImage = { def site = SiteInfo.get(params.id)// get the record response.outputStream << site.img // write the image to the outputstream response.outputStream.flush() }

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• ASP.NET NVC - Add XHTML into validation error messages

  - by Neil

  Hi, Just starting with ASP.Net MVC and have hit a bit of a snag regarding validation messages. I've a custom validation attribute assigned to my class validate several properties on my model. When this validation fails, we'd like the error message to contain XHTML mark-up, including a link to help page, (this was done in the original WebForms project as a ASP:Panel). At the moment the XHTML tags such as "< a ", in the ErrorMessage are being rendered to the screen. Is there any way to get the ValidationSummary to render the XHTML markup correctly? Or is there a better way to handle this kind of validation? Thanks

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• Custom Validation with MVC2 and EF4

  - by csharpnoob

  Hi, on ScottGu's Blog is an Example how to use MVC2 Custom Validation with EF4: http://weblogs.asp.net/scottgu/archive/2010/01/15/asp-net-mvc-2-model-validation.aspx So here the Problem: When the Designer in VS2010 creates the Objects for the DB, along to the example you have to add [MetadataType(typeof(Person_validation))] Annotation to that class. But when i change anything in the Designer all these Annotations are lost. Is it possible to keep self made changes to the edmx file, or is there any better way of applying System.ComponentModel.DataAnnotations to the generated Entities? Thanks.

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