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• Getting Started with Prism (aka Composite Application Guidance for WPF and Silverlight)

  - by dotneteer

  Overview Prism is a framework from the Microsoft Patterns and Practice team that allow you to create WPF and Silverlight in a modular way. It is especially valuable for larger projects in which a large number of developers can develop in parallel. Prism achieves its goal by supplying several services: · Dependency Injection (DI) and Inversion of control (IoC): By using DI, Prism takes away the responsibility of instantiating and managing the life time of dependency objects from individual components to a container. Prism relies on containers to discover, manage and compose large number of objects. By varying the configuration, the container can also inject mock objects for unit testing. Out of the box, Prism supports Unity and MEF as container although it is possible to use other containers by subclassing the Bootstrapper class. · Modularity and Region: Prism supplies the framework to split application into modules from the application shell. Each module is a library project that contains both UI and code and is responsible to initialize itself when loaded by the shell. Each window can be further divided into regions. A region is a user control with associated model. · Model, view and view-model (MVVM) pattern: Prism promotes the user MVVM. The use of DI container makes it much easier to inject model into view. WPF already has excellent data binding and commanding mechanism. To be productive with Prism, it is important to understand WPF data binding and commanding well. · Event-aggregation: Prism promotes loosely coupled components. Prism discourages for components from different modules to communicate each other, thus leading to dependency. Instead, Prism supplies an event-aggregation mechanism that allows components to publish and subscribe events without knowing each other. Architecture In the following, I will go into a little more detail on the services provided by Prism. Bootstrapper In a typical WPF application, application start-up is controls by App.xaml and its code behind. The main window of the application is typically specified in the App.xaml file. In a Prism application, we start a bootstrapper in the App class and delegate the duty of main window to the bootstrapper. The bootstrapper will start a dependency-injection container so all future object instantiations are managed by the container. Out of box, Prism provides the UnityBootstrapper and MefUnityBootstrapper abstract classes. All application needs to either provide a concrete implementation of one of these bootstrappers, or alternatively, subclass the Bootstrapper class with another DI container. A concrete bootstrapper class must implement the CreateShell method. Its responsibility is to resolve and create the Shell object through the DI container to serve as the main window for the application. The other important method to override is ConfigureModuleCatalog. The bootstrapper can register modules for the application. In a more advance scenario, an application does not have to know all its modules at compile time. Modules can be discovered at run time. Readers to refer to one of the Open Modularity Quick Starts for more information. Modules Once modules are registered with or discovered by Prism, they are instantiated by the DI container and their Initialize method is called. The DI container can inject into a module a region registry that implements IRegionViewRegistry interface. The module, in its Initialize method, can then call RegisterViewWithRegion method of the registry to register its regions. Regions Regions, once registered, are managed by the RegionManager. The shell can then load regions either through the RegionManager.RegionName attached property or dynamically through code. When a view is created by the region manager, the DI container can inject view model and other services into the view. The view then has a reference to the view model through which it can interact with backend services. Service locator Although it is possible to inject services into dependent classes through a DI container, an alternative way is to use the ServiceLocator to retrieve a service on demard. Prism supplies a service locator implementation and it is possible to get an instance of the service by calling: ServiceLocator.Current.GetInstance<IServiceType>() Event aggregator Prism supplies an IEventAggregator interface and implementation that can be injected into any class that needs to communicate with each other in a loosely-coupled fashion. The event aggregator uses a publisher/subscriber model. A class can publishes an event by calling eventAggregator.GetEvent<EventType>().Publish(parameter) to raise an event. Other classes can subscribe the event by calling eventAggregator.GetEvent<EventType>().Subscribe(EventHandler, other options). Getting started The easiest way to get started with Prism is to go through the Prism Hands-On labs and look at the Hello World QuickStart. The Hello World QuickStart shows how bootstrapper, modules and region works. Next, I would recommend you to look at the Stock Trader Reference Implementation. It is a more in depth example that resemble we want to set up an application. Several other QuickStarts cover individual Prism services. Some scenarios, such as dynamic module discovery, are more advanced. Apart from the official prism document, you can get an overview by reading Glen Block’s MSDN Magazine article. I have found the best free training material is from the Boise Code Camp. To be effective with Prism, it is important to understands key concepts of WPF well first, such as the DependencyProperty system, data binding, resource, theme and ICommand. It is also important to know your DI container of choice well. I will try to explorer these subjects in depth in the future. Testimony Recently, I worked on a desktop WPF application using Prism. I had a wonderful experience with Prism. The Prism is flexible enough even in the presence of third party controls such as Telerik WPF controls. We have never encountered any significant obstacle.

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• GLSL Atmospheric Scattering Issue

  - by mtf1200

  I am attempting to use Sean O'Neil's shaders to accomplish atmospheric scattering. For now I am just using SkyFromSpace and GroundFromSpace. The atmosphere works fine but the planet itself is just a giant dark sphere with a white blotch that follows the camera. I think the problem might rest in the "v3Attenuation" variable as when this is removed the sphere is show (albeit without scattering). Here is the vertex shader. Thanks for the time! uniform mat4 g_WorldViewProjectionMatrix; uniform mat4 g_WorldMatrix; uniform vec3 m_v3CameraPos; // The camera's current position uniform vec3 m_v3LightPos; // The direction vector to the light source uniform vec3 m_v3InvWavelength; // 1 / pow(wavelength, 4) for the red, green, and blue channels uniform float m_fCameraHeight; // The camera's current height uniform float m_fCameraHeight2; // fCameraHeight^2 uniform float m_fOuterRadius; // The outer (atmosphere) radius uniform float m_fOuterRadius2; // fOuterRadius^2 uniform float m_fInnerRadius; // The inner (planetary) radius uniform float m_fInnerRadius2; // fInnerRadius^2 uniform float m_fKrESun; // Kr * ESun uniform float m_fKmESun; // Km * ESun uniform float m_fKr4PI; // Kr * 4 * PI uniform float m_fKm4PI; // Km * 4 * PI uniform float m_fScale; // 1 / (fOuterRadius - fInnerRadius) uniform float m_fScaleDepth; // The scale depth (i.e. the altitude at which the atmosphere's average density is found) uniform float m_fScaleOverScaleDepth; // fScale / fScaleDepth attribute vec4 inPosition; vec3 v3ELightPos = vec3(g_WorldMatrix * vec4(m_v3LightPos, 1.0)); vec3 v3ECameraPos= vec3(g_WorldMatrix * vec4(m_v3CameraPos, 1.0)); const int nSamples = 2; const float fSamples = 2.0; varying vec4 color; float scale(float fCos) { float x = 1.0 - fCos; return m_fScaleDepth * exp(-0.00287 + x*(0.459 + x*(3.83 + x*(-6.80 + x*5.25)))); } void main(void) { gl_Position = g_WorldViewProjectionMatrix * inPosition; // Get the ray from the camera to the vertex and its length (which is the far point of the ray passing through the atmosphere) vec3 v3Pos = vec3(g_WorldMatrix * inPosition); vec3 v3Ray = v3Pos - v3ECameraPos; float fFar = length(v3Ray); v3Ray /= fFar; // Calculate the closest intersection of the ray with the outer atmosphere (which is the near point of the ray passing through the atmosphere) float B = 2.0 * dot(m_v3CameraPos, v3Ray); float C = m_fCameraHeight2 - m_fOuterRadius2; float fDet = max(0.0, B*B - 4.0 * C); float fNear = 0.5 * (-B - sqrt(fDet)); // Calculate the ray's starting position, then calculate its scattering offset vec3 v3Start = m_v3CameraPos + v3Ray * fNear; fFar -= fNear; float fDepth = exp((m_fInnerRadius - m_fOuterRadius) / m_fScaleDepth); float fCameraAngle = dot(-v3Ray, v3Pos) / fFar; float fLightAngle = dot(v3ELightPos, v3Pos) / fFar; float fCameraScale = scale(fCameraAngle); float fLightScale = scale(fLightAngle); float fCameraOffset = fDepth*fCameraScale; float fTemp = (fLightScale + fCameraScale); // Initialize the scattering loop variables float fSampleLength = fFar / fSamples; float fScaledLength = fSampleLength * m_fScale; vec3 v3SampleRay = v3Ray * fSampleLength; vec3 v3SamplePoint = v3Start + v3SampleRay * 0.5; // Now loop through the sample rays vec3 v3FrontColor = vec3(0.0, 0.0, 0.0); vec3 v3Attenuate; for(int i=0; i<nSamples; i++) { float fHeight = length(v3SamplePoint); float fDepth = exp(m_fScaleOverScaleDepth * (m_fInnerRadius - fHeight)); float fScatter = fDepth*fTemp - fCameraOffset; v3Attenuate = exp(-fScatter * (m_v3InvWavelength * m_fKr4PI + m_fKm4PI)); v3FrontColor += v3Attenuate * (fDepth * fScaledLength); v3SamplePoint += v3SampleRay; } vec3 first = v3FrontColor * (m_v3InvWavelength * m_fKrESun + m_fKmESun); vec3 secondary = v3Attenuate; color = vec4((first + vec3(0.25,0.25,0.25) * secondary), 1.0); // ^^ that color is passed to the frag shader and is used as the gl_FragColor } Here is also an image of the problem image

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• The Unspoken - The Why of GC Ergonomics

  - by jonthecollector

  Do you use GC ergonomics, -XX:+UseAdaptiveSizePolicy, with the UseParallelGC collector? The jist of GC ergonomics for that collector is that it tries to grow or shrink the heap to meet a specified goal. The goals that you can choose are maximum pause time and/or throughput. Don't get too excited there. I'm speaking about UseParallelGC (the throughput collector) so there are definite limits to what pause goals can be achieved. When you say out loud "I don't care about pause times, give me the best throughput I can get" and then say to yourself "Well, maybe 10 seconds really is too long", then think about a pause time goal. By default there is no pause time goal and the throughput goal is high (98% of the time doing application work and 2% of the time doing GC work). You can get more details on this in my very first blog. GC ergonomics The UseG1GC has its own version of GC ergonomics, but I'll be talking only about the UseParallelGC version. If you use this option and wanted to know what it (GC ergonomics) was thinking, try -XX:AdaptiveSizePolicyOutputInterval=1 This will print out information every i-th GC (above i is 1) about what the GC ergonomics to trying to do. For example, UseAdaptiveSizePolicy actions to meet *** throughput goal *** GC overhead (%) Young generation: 16.10 (attempted to grow) Tenured generation: 4.67 (attempted to grow) Tenuring threshold: (attempted to decrease to balance GC costs) = 1 GC ergonomics tries to meet (in order) Pause time goal Throughput goal Minimum footprint The first line says that it's trying to meet the throughput goal. UseAdaptiveSizePolicy actions to meet *** throughput goal *** This run has the default pause time goal (i.e., no pause time goal) so it is trying to reach a 98% throughput. The lines Young generation: 16.10 (attempted to grow) Tenured generation: 4.67 (attempted to grow) say that we're currently spending about 16% of the time doing young GC's and about 5% of the time doing full GC's. These percentages are a decaying, weighted average (earlier contributions to the average are given less weight). The source code is available as part of the OpenJDK so you can take a look at it if you want the exact definition. GC ergonomics is trying to increase the throughput by growing the heap (so says the "attempted to grow"). The last line Tenuring threshold: (attempted to decrease to balance GC costs) = 1 says that the ergonomics is trying to balance the GC times between young GC's and full GC's by decreasing the tenuring threshold. During a young collection the younger objects are copied to the survivor spaces while the older objects are copied to the tenured generation. Younger and older are defined by the tenuring threshold. If the tenuring threshold hold is 4, an object that has survived fewer than 4 young collections (and has remained in the young generation by being copied to the part of the young generation called a survivor space) it is younger and copied again to a survivor space. If it has survived 4 or more young collections, it is older and gets copied to the tenured generation. A lower tenuring threshold moves objects more eagerly to the tenured generation and, conversely a higher tenuring threshold keeps copying objects between survivor spaces longer. The tenuring threshold varies dynamically with the UseParallelGC collector. That is different than our other collectors which have a static tenuring threshold. GC ergonomics tries to balance the amount of work done by the young GC's and the full GC's by varying the tenuring threshold. Want more work done in the young GC's? Keep objects longer in the survivor spaces by increasing the tenuring threshold. This is an example of the output when GC ergonomics is trying to achieve a pause time goal UseAdaptiveSizePolicy actions to meet *** pause time goal *** GC overhead (%) Young generation: 20.74 (no change) Tenured generation: 31.70 (attempted to shrink) The pause goal was set at 50 millisecs and the last GC was 0.415: [Full GC (Ergonomics) [PSYoungGen: 2048K-0K(26624K)] [ParOldGen: 26095K-9711K(28992K)] 28143K-9711K(55616K), [Metaspace: 1719K-1719K(2473K/6528K)], 0.0758940 secs] [Times: user=0.28 sys=0.00, real=0.08 secs] The full collection took about 76 millisecs so GC ergonomics wants to shrink the tenured generation to reduce that pause time. The previous young GC was 0.346: [GC (Allocation Failure) [PSYoungGen: 26624K-2048K(26624K)] 40547K-22223K(56768K), 0.0136501 secs] [Times: user=0.06 sys=0.00, real=0.02 secs] so the pause time there was about 14 millisecs so no changes are needed. If trying to meet a pause time goal, the generations are typically shrunk. With a pause time goal in play, watch the GC overhead numbers and you will usually see the cost of setting a pause time goal (i.e., throughput goes down). If the pause goal is too low, you won't achieve your pause time goal and you will spend all your time doing GC. GC ergonomics is meant to be simple because it is meant to be used by anyone. It was not meant to be mysterious and so this output was added. If you don't like what GC ergonomics is doing, you can turn it off with -XX:-UseAdaptiveSizePolicy, but be pre-warned that you have to manage the size of the generations explicitly. If UseAdaptiveSizePolicy is turned off, the heap does not grow. The size of the heap (and the generations) at the start of execution is always the size of the heap. I don't like that and tried to fix it once (with some help from an OpenJDK contributor) but it unfortunately never made it out the door. I still have hope though. Just a side note. With the default throughput goal of 98% the heap often grows to it's maximum value and stays there. Definitely reduce the throughput goal if footprint is important. Start with -XX:GCTimeRatio=4 for a more modest throughput goal (%20 of the time spent in GC). A higher value means a smaller amount of time in GC (as the throughput goal).

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• Day 4 - Game Sprites In Action

  - by dapostolov

  Yesterday I drew an image on the screen. Most exciting, but ... I spent more time blogging about it then actual coding. So this next little while I'm going to streamline my game and research and simply post key notes. Quick notes on the last session: The most important thing I wanted to point out were the following methods:           spriteBatch.Begin(SpriteBlendMode.AlphaBlend);           spriteBatch.Draw(sprite, position, Color.White);           spriteBatch.End(); The spriteBatch object is used to draw Textures and a 2D texture is called a Sprite A texture is generally an image, which is called an Asset in XNA The Draw Method in the Game1.cs is looped (until exit) and utilises the spriteBatch object to draw a Scene To begin drawing a Scene you call the Begin Method. To end a Scene you call the End Method. And to place an image on the Scene you call the Draw method. The most simple implementation of the draw method is:           spriteBatch.Draw(sprite, position, Color.White); 1) sprite - the 2D texture you loaded to draw 2) position - the 2d vector, a set of x & y coordinates 3) Color.White - the tint to apply to the texture, in this case, white light = nothing, nada, no tint. Game Sprites In Action! Today, I played around with Draw methods to get comfortable with their "quirks". The following is an example of the above draw method, but with more parameters available for us to use. Let's investigate!             spriteBatch.Draw(sprite, position2, null, Color.White, MathHelper.ToRadians(45.0f), new Vector2(sprite.Width / 2, sprite.Height / 2), 1.0F, SpriteEffects.None, 0.0F); The parameters (in order): 1) sprite  the texture to display 2) position2 the position on the screen / scene this can also be a rectangle 3) null the portion of the image to display within an image null = display full image this is generally used for animation strips / grids (more on this below) 4) Color.White Texture tinting White = no tint 5) MathHelper.ToRadians(45.0f) rotation of the object, in this case 45 degrees rotates from the set plotting point. 6) new Vector(0,0) the plotting point in this case the top left corner the image will rotate from the top left of the texture in the code above, the point is set to the middle of the image. 7) 1.0f Image scaling (1x) 8) SpriteEffects.None you can flip the image horizontally or vertically 9) 0.0f The z index of the image. 0 = closer, 1 behind? And playing around with different combinations I was able to come up with the following whacky display:   Checking off Yesterdays Intention List: learn game development terminology (in progress) - We learned sprite, scene, texture, and asset. how to place and position (rotate) a static image on the screen (completed) - The thing to note was, it's was in radians and I found a cool helper method to convert degrees into radians. Also, the image rotates from it's specified point. how to layer static images on the screen (completed) - I couldn't seem to get the zIndex working, but one things for sure, the order you draw the image in also determines how it is rendered on the screen. understand image scaling (in progress) - I'm not sure I have this fully covered, but for the most part plug a number in the scaling field and the image grows / shrinks accordingly. can we reuse images? (completed) - yes, I loaded one image and plotted the bugger all over the screen. understand how framerate is handled in XNA (in progress) - I hacked together some code to display the framerate each second. A framerate of 60 appears to be the standard. Interesting to note, the GameTime object does provide you with some cool timing capabilities, such as...is the game running slow? Need to investigate this down the road. how to display text , basic shapes, and colors on the screen (in progress) - i got text rendered on the screen, and i understand containing rectangles. However, I didn't display "shapes" & "colors" how to interact with an image (collision of user input?) (todo) how to animate an image and understand basic animation techniques (in progress) - I was able to create a stripe animation of numbers ranging from 1 - 4, each block was 40 x 40 pixles for a total stripe size of 160 x 40. Using the portion (source Rectangle) parameter, i limited this display to each section at varying intervals. It was interesting to note my first implementation animated at rocket speed. I then tried to create a smoother animation by limiting the redraw capacity, which seemed to work. I guess a little more research will have to be put into this for animating characters / scenes. how to detect colliding images or screen edges (todo) - but the rectangle object can detect collisions I believe. how to manipulate the image, lets say colors, stretching (in progress) - I haven't figured out how to modify a specific color to be another color, but the tinting parameter definately could be used. As for stretching, use the rectangle object as the positioning and the image will stretch to fit! how to focus on a segment of an image...like only displaying a frame on a film reel (completed) - as per basic animation techniques what's the best way to manage images (compression, storage, location, prevent artwork theft, etc.) (todo) Tomorrows Intention Tomorrow I am going to take a stab at rendering a game menu and from there I'm going to investigate how I can improve upon the code and techniques. Intention List: Render a menu, fancy or not Show the mouse cursor Hook up click event A basic animation of somesort Investigate image / menu techniques D.

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• Weird y offset when using custom frag shader (Cocos2d-x)

  - by Mister Guacamole

  I'm trying to mask a sprite so I wrote a simple fragment shader that renders only the pixels that are not hidden under another texture (the mask). The problem is that it seems my texture has its y-coordinate offset after passing through the shader. This is the init method of the sprite (GroundZone) I want to mask: bool GroundZone::initWithSize(Size size) { // [...] // Setup the mask of the sprite m_mask = RenderTexture::create(textureWidth, textureHeight); m_mask->retain(); m_mask->setKeepMatrix(true); Texture2D *maskTexture = m_mask->getSprite()->getTexture(); maskTexture->setAliasTexParameters(); // Disable linear interpolation on the mask // Load the custom frag shader with a default vert shader as the sprite’s program FileUtils *fileUtils = FileUtils::getInstance(); string vertexSource = ccPositionTextureA8Color_vert; string fragmentSource = fileUtils->getStringFromFile( fileUtils->fullPathForFilename("CustomShader_AlphaMask_frag.fsh")); GLProgram *shader = new GLProgram; shader->initWithByteArrays(vertexSource.c_str(), fragmentSource.c_str()); shader->bindAttribLocation(GLProgram::ATTRIBUTE_NAME_POSITION, GLProgram::VERTEX_ATTRIB_POSITION); shader->bindAttribLocation(GLProgram::ATTRIBUTE_NAME_TEX_COORD, GLProgram::VERTEX_ATTRIB_TEX_COORDS); shader->link(); CHECK_GL_ERROR_DEBUG(); shader->updateUniforms(); CHECK_GL_ERROR_DEBUG(); int maskTexUniformLoc = shader->getUniformLocationForName("u_alphaMaskTexture"); shader->setUniformLocationWith1i(maskTexUniformLoc, 1); this->setShaderProgram(shader); shader->release(); // [...] } These are the custom drawing methods for actually drawing the mask over the sprite: You need to know that m_mask is modified externally by another class, the onDraw() method only render it. void GroundZone::draw(Renderer *renderer, const kmMat4 &transform, bool transformUpdated) { m_renderCommand.init(_globalZOrder); m_renderCommand.func = CC_CALLBACK_0(GroundZone::onDraw, this, transform, transformUpdated); renderer->addCommand(&m_renderCommand); Sprite::draw(renderer, transform, transformUpdated); } void GroundZone::onDraw(const kmMat4 &transform, bool transformUpdated) { GLProgram *shader = this->getShaderProgram(); shader->use(); glActiveTexture(GL_TEXTURE1); glBindTexture(GL_TEXTURE_2D, m_mask->getSprite()->getTexture()->getName()); glActiveTexture(GL_TEXTURE0); } Below is the method (located in another class, GroundLayer) that modify the mask by drawing a line from point start to point end. Both points are in Cocos2d coordinates (Point (0,0) is down-left). void GroundLayer::drawTunnel(Point start, Point end) { // To dig a line, we need first to get the texture of the zone we will be digging into. Then we get the // relative position of the start and end point in the zone's node space. Finally we use the custom shader to // draw a mask over the existing texture. for (auto it = _children.begin(); it != _children.end(); it++) { GroundZone *zone = static_cast<GroundZone *>(*it); Point nodeStart = zone->convertToNodeSpace(start); Point nodeEnd = zone->convertToNodeSpace(end); // Now that we have our two points converted to node space, it's easy to draw a mask that contains a line // going from the start point to the end point and that is then applied over the current texture. Size groundZoneSize = zone->getContentSize(); RenderTexture *rt = zone->getMask(); rt->begin(); { // Draw a line going from start and going to end in the texture, the line will act as a mask over the // existing texture DrawNode *line = DrawNode::create(); line->retain(); line->drawSegment(nodeStart, nodeEnd, 20, Color4F::RED); line->visit(); } rt->end(); } } Finally, here's the custom shader I wrote. #ifdef GL_ES precision mediump float; #endif varying vec2 v_texCoord; uniform sampler2D u_texture; uniform sampler2D u_alphaMaskTexture; void main() { float maskAlpha = texture2D(u_alphaMaskTexture, v_texCoord).a; float texAlpha = texture2D(u_texture, v_texCoord).a; float blendAlpha = (1.0 - maskAlpha) * texAlpha; // Show only where mask is invisible vec3 texColor = texture2D(u_texture, v_texCoord).rgb; gl_FragColor = vec4(texColor, blendAlpha); return; } I got a problem with the y coordinates. Indeed, it seems that once it has passed through my custom shader, the sprite's texture is not at the right place: Without custom shader (the sprite is the brown thing): With custom shader: What's going on here? Thanks :) EDIT It looks like after passing through the shader when I set the position of the sprite I set it in points, with (0,0) being in the top-right. Indeed, when I do sprite->setPosition(320, 480), the sprite is perfectly placed at the top of the screen.

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• Community Branching

  - by Dane Morgridge

  As some may have noticed, I have taken a liking to Ruby (and Rails in particular) quite a bit recently. This last weekend I spoke at the NYC Code Camp on a comparison of ASP.NET and Rails as well as an intro to Entity Framework talk.  I am speaking at RubyNation in April and have submitted to other ruby conferences around the area and I am also doing a Rails and MongoDB talk at the Philly Code Camp in April. Before you start to think this is my "I'm leaving .NET post", which it isn't so I need to clarify. I am not, nor do I intend to any time in the near future plan on abandoning .NET.  I am simply branching out into another community based on a development technology that I very much enjoy.  If you look at my twitter bio, you will see that I am into Entity Framework, Ruby on Rails, C++ and ASP.NET MVC, and not necessarily in that order.  I know you're probably thinking to your self that I am crazy, which is probably true on several levels (especially the C++ part). I was actually crazy enough at the NYC Code Camp to show up wearing a Linux t-shirt, presenting with my MacBook Pro on Entity Framework, ASP.NET MVC and Rails. (I did get pelted in the head with candy by Rachel Appel for it though) At all of the code camps I am submitting to this year, i will be submitting sessions on likely all four topics, and some sessions will be a combination of 2 or more.  For example, my "ASP.NET MVC: A Gateway To Rails?" talk touches ASP.NET MVC, Entity Framework Code First and Rails. Simply put (and I talk about this in my MVC & Rails talk) is that learning and using Rails has made me a better ASP.NET MVC developer. Just one example of this is helper methods.  When I started working with ASP.NET MVC, I didn't really want to use helpers and preferred to just use standard html tags, especially where links were concerned.  It was just me being stubborn and not really seeing all of the benefit of the helpers.  To my defense, coming from WebForms, I wanted to be as bare metal as possible and it seemed at first like a lot of the helpers were an unnecessary abstraction. I took my first look at Rails back in v1 and didn't spend very much time with it so I dismissed it and went on my merry ASP.NET WebForms way.  Then I picked up ASP.NET MVC and grasped the MVC pattern itself much better. After this, I took another look at Rails and everything made sense.  I decided then to learn Rails. (I think it is important for developers to learn new languages and platforms regularly so it was a natural progression for me) I wanted to learn it the right way, so when I dug into code, everyone used helpers everywhere for pretty much everything possible. I took some time to dig in and found out how helpful they were and subsequently realized how awesome they were in ASP.NET MVC also and started using them. In short, I love Rails (and Ruby in general).  I also love ASP.NET MVC and Entity Framework and yes I still love C++.  I have varying degrees of love for them individually at any given moment and it is likely to shift based on the current project I am working on.  I know you're thinking it so before you ask the question. "Which do I use when?", I'm going to give the standard developer answer of: It depends.  There are a lot of factors that I am not going to even go into that would go into a decision.  The most basic question I would ask though is,  does this project depend on .NET?  If it does, then I'd say that ASP.NET MVC is probably going to be the more logical choice and I am going to leave it at that.  I am working on projects right now in both technologies and I don't see that changing anytime soon (one project even uses both). With all that being said, you'll find me at code camps, conferences and user groups presenting on .NET, Ruby or both, writing about .NET and Ruby and I will likely be blogging on both in the future.  I know of others that have successfully branched out to other communities and with any luck I'll be successful at it too. On a (sorta) side note, I read a post by Justin Etheredge the other day that pretty much sums up my feelings about Ruby as a language.  I highly recommend checking it out: What Is So Great About Ruby?

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• Many Different Things Rolled into a Ball

  - by MOSSLover

  Yeah I know I don’t blog much anymore, because life has taken me places that don’t involve the interwebs unfortunately.  I am in the midst of planning two events, starting a non for profit, creating more sessions for various conferences, submitting to various conferences, working a 40 hour a week job, attempting to hang out with boyfriend/friends/family.  So you can see that list does not include this blog sadly that’s how it goes sometimes.  The bottom piece very important over any of the top pieces.  I haven’t seen St. Louis in a while and I get to go back.  I was gone from home for MVP Summit and Best Practices Conference, so the boyfriend and cat didn’t get to see me either for a bit.  Then you have to add in the whole toilet being broken fiasco this week.  Maintenance really thought it would be cool to turn off the ability to flush.  I mean who does that?  Then when we call the owner he comes by turns it on and we figure it was an accident, because well the next day no one came by to tell us there was a leak.  It was all kinds of strangeness and involved me running to other people’s toilets.  As Dan Usher would say, I was a sad panda for a few days.  So I guess I wanted to post a few thoughts here just because I can.  I do not like multiple content editor webparts embedded with html files in numerous pages doing the same thing.  I will tell you why I don’t like these particular webparts and the way they are being used.  First off if you have a bunch of pages with script includes it’s about time you should just dump them into the masterpage.  Why bother finding all 20 pages and changing those pages when you can just use a single masterpage that already exists? The other thing that is bothering me days is screen scraping.  Just don’t do it, because in 2010 you will find the UI is substantially slower.  I understand you are new and you have no idea what to do.  You are also using 2007 am I right?  So then you need to go to codeplex.com and type in a search for SPServices.  Download it, use it, love it and then have it’s babies (well maybe don’t go so far this is not the GRID in Tron). If you have a ton of constants in your code why did you not go in and create a webpart with a bunch of properties and/or link to a configuration list hidden in the browser?  This type of property and list could help you out in the long run.  The power users and administrators can now change the control without you having to compile it over and over again.  It’s good stuff.  Also, you can change the control without compiling it, especially in 2007 where you have to do a farm solution.  In 2010 you can do a sandbox solution I guess, but shouldn’t you make it as easy and supportable as possible for other users? In conclusion I’m an angry person when it comes to viewing something repeatedly and analyzing it in a system.  Now we will move on to the next topic…MVP Summit…So yeah I can’t really talk about particulars, but I can talk about my experience as a person.  Don’t build something up to be cooler than it is only to be dropped from your 10,000 foot perch.  My experience was great, but the content overall was something to be desired.  It’s ok I got to meet a lot of people I would not have met if I had not gone.  Some of it was surreal, such as product group members showing up and talking to us.  It was pretty neat.  Plus I never had the chance to get to that mythical MS Office in Redmond.  Prior to Summit it was like Rainbow Brites unicorn trying taunting me on television when I was a kid.  So I guess with all that said I give it a B.  It was awesome in some way, but lacking in other ways.  The cool part is that I got to go.  Would I have lived without going? Yes, but it was still cool. I could prattle on about other things and make this post massive, but I’m going to pass and give myself a piece of Sunday to play Rockband and do 800 other things.  I hope the two of you who read this blog are well.  I’ll catch you all at another juncture.  Have a good weekend and varying holidays in between. Technorati Tags: SharePoint,MVP Summit,JQuery,Javascript

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• Creating SparseImages for Pivot

  - by John Conwell

  Learning how to programmatically make collections for Microsoft Live Labs Pivot has been a pretty interesting ride. There are very few examples out there, and the folks at MS Live Labs are often slow on any feedback.  But that is what Reflector is for, right? Well, I was creating these InfoCard images (similar to the Car images in the "New Cars" sample collection that that MS created for Pivot), and wanted to put a Tag Cloud into the info card.  The problem was the size of the tag cloud might vary in order for all the tags to fit into the tag cloud (often times being bigger than the info card itself).  This was because the varying word lengths and calculated font sizes. So, to fix this, I made the tag cloud its own separate image from the info card.  Then, I would create a sparse image out of the two images, where the tag cloud fit into a small section of the info card.  This would allow the user to see the info card, but then zoom into the tag cloud and see all the tags at a normal resolution.  Kind'a cool. But...I couldn't find one code example (not one!) of how to create a sparse image.  There is one page on the SeaDragon site (http://www.seadragon.com/developer/creating-content/deep-zoom-tools/) that gives over the API for creating images and collections, and it sparsely goes over how to create a sparse image, but unless you are familiar with the API already, the documentation doesn't help very much. The key is the Image.ViewportWidth and Image.ViewportOrigin properties of the image that is getting super imposed on the main image.  I'll walk through the code below.  I've setup a couple Point structs to represent the parent and sub image sizes, as well as where on the parent I want to position the sub image.  Next, create the parent image.  This is pretty straight forward.  Then I create the sub image.  Then I calculate several ratios; the height to width ratio of the sub image, the width ratio of the sub image to the parent image, the height ratio of the sub image to the parent image, then the X and Y coordinates on the parent image where I want the sub image to be placed represented as a ratio of the position to the parent image size. After all these ratios have been calculated, I use them to calculate the Image.ViewportWidth and Image.ViewportOrigin values, then pass the image objects into the SparseImageCreator and call Create. The key thing that was really missing from the API documentation page is that when setting up your sub images, everything is expressed in a ratio in relation to the main parent image.  If I had known this, it would have saved me a lot of trial and error time.  And how did I figure this out?  Reflector of course!  There is a tool called Deep Zoom Composer that came from MS Live Labs which can create a sparse image.  I just dug around the tool's code until I found the method that create sparse images.  But seriously...look at the API documentation from the SeaDragon size and look at the code below and tell me if the documentation would have helped you at all.  I don't think so!   public static void WriteDeepZoomSparseImage(string mainImagePath, string subImagePath, string destination) {     Point parentImageSize = new Point(720, 420);     Point subImageSize = new Point(490, 310);     Point subImageLocation = new Point(196, 17);     List<Image> images = new List<Image>();     //create main image     Image mainImage = new Image(mainImagePath);     mainImage.Size = parentImageSize;     images.Add(mainImage);     //create sub image     Image subImage = new Image(subImagePath);     double hwRatio = subImageSize.X/subImageSize.Y;            // height width ratio of the tag cloud     double nodeWidth = subImageSize.X/parentImageSize.X;        // sub image width to parent image width ratio     double nodeHeight = subImageSize.Y / parentImageSize.Y;    // sub image height to parent image height ratio     double nodeX = subImageLocation.X/parentImageSize.X;       //x cordinate position on parent / width of parent     double nodeY = subImageLocation.Y / parentImageSize.Y;     //y cordinate position on parent / height of parent     subImage.ViewportWidth = (nodeWidth < double.Epsilon) ? 1.0 : (1.0 / nodeWidth);     subImage.ViewportOrigin = new Point(         (nodeWidth < double.Epsilon) ? -1.0 : (-nodeX / nodeWidth),         (nodeHeight < double.Epsilon) ? -1.0 : ((-nodeY / nodeHeight) / hwRatio));     images.Add(subImage);     //create sparse image     SparseImageCreator creator = new SparseImageCreator();     creator.Create(images, destination); }

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• CPU Usage in Very Large Coherence Clusters

  - by jpurdy

  When sizing Coherence installations, one of the complicating factors is that these installations (by their very nature) tend to be application-specific, with some being large, memory-intensive caches, with others acting as I/O-intensive transaction-processing platforms, and still others performing CPU-intensive calculations across the data grid. Regardless of the primary resource requirements, Coherence sizing calculations are inherently empirical, in that there are so many permutations that a simple spreadsheet approach to sizing is rarely optimal (though it can provide a good starting estimate). So we typically recommend measuring actual resource usage (primarily CPU cycles, network bandwidth and memory) at a given load, and then extrapolating from those measurements. Of course there may be multiple types of load, and these may have varying degrees of correlation -- for example, an increased request rate may drive up the number of objects "pinned" in memory at any point, but the increase may be less than linear if those objects are naturally shared by concurrent requests. But for most reasonably-designed applications, a linear resource model will be reasonably accurate for most levels of scale. However, at extreme scale, sizing becomes a bit more complicated as certain cluster management operations -- while very infrequent -- become increasingly critical. This is because certain operations do not naturally tend to scale out. In a small cluster, sizing is primarily driven by the request rate, required cache size, or other application-driven metrics. In larger clusters (e.g. those with hundreds of cluster members), certain infrastructure tasks become intensive, in particular those related to members joining and leaving the cluster, such as introducing new cluster members to the rest of the cluster, or publishing the location of partitions during rebalancing. These tasks have a strong tendency to require all updates to be routed via a single member for the sake of cluster stability and data integrity. Fortunately that member is dynamically assigned in Coherence, so it is not a single point of failure, but it may still become a single point of bottleneck (until the cluster finishes its reconfiguration, at which point this member will have a similar load to the rest of the members). The most common cause of scaling issues in large clusters is disabling multicast (by configuring well-known addresses, aka WKA). This obviously impacts network usage, but it also has a large impact on CPU usage, primarily since the senior member must directly communicate certain messages with every other cluster member, and this communication requires significant CPU time. In particular, the need to notify the rest of the cluster about membership changes and corresponding partition reassignments adds stress to the senior member. Given that portions of the network stack may tend to be single-threaded (both in Coherence and the underlying OS), this may be even more problematic on servers with poor single-threaded performance. As a result of this, some extremely large clusters may be configured with a smaller number of partitions than ideal. This results in the size of each partition being increased. When a cache server fails, the other servers will use their fractional backups to recover the state of that server (and take over responsibility for their backed-up portion of that state). The finest granularity of this recovery is a single partition, and the single service thread can not accept new requests during this recovery. Ordinarily, recovery is practically instantaneous (it is roughly equivalent to the time required to iterate over a set of backup backing map entries and move them to the primary backing map in the same JVM). But certain factors can increase this duration drastically (to several seconds): large partitions, sufficiently slow single-threaded CPU performance, many or expensive indexes to rebuild, etc. The solution of course is to mitigate each of those factors but in many cases this may be challenging. Larger clusters also lead to the temptation to place more load on the available hardware resources, spreading CPU resources thin. As an example, while we've long been aware of how garbage collection can cause significant pauses, it usually isn't viewed as a major consumer of CPU (in terms of overall system throughput). Typically, the use of a concurrent collector allows greater responsiveness by minimizing pause times, at the cost of reducing system throughput. However, at a recent engagement, we were forced to turn off the concurrent collector and use a traditional parallel "stop the world" collector to reduce CPU usage to an acceptable level. In summary, there are some less obvious factors that may result in excessive CPU consumption in a larger cluster, so it is even more critical to test at full scale, even though allocating sufficient hardware may often be much more difficult for these large clusters.

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• Using Definition of Done to Drive Agile Maturity

  - by Dylan Smith

  I’ve been an Agile Coach at a lot of different clients over the years, and I want to share an approach I use to help them adopt and mature over time. It’s important to realize that “Agile” is not a black/white yes/no thing. Teams can be varying degrees of agile. I think of this as their agile maturity level. When I coach teams I want them to start out being a little agile, and get more agile as they mature. The approach I teach them is to use the definition of done as a technique to continuously improve their agile maturity over time. We’re probably all familiar with the concept of “Done Done” that represents what *actually* being done a feature means. Not just when a developer says he’s done right after he writes that last line of code that makes the feature kind-of work. Done Done means the coding is done, it’s been tested, installers and deployment packages have been created, user manuals have been updated, architecture docs have been updated, etc. To enable teams to internalize the concept of “Done Done”, they usually get together and come up with their Definition of Done (DoD) that defines all the activities that need to be completed before a feature is considered Done Done. The Done Done technique typically is applied only to features (aka User Stories). What I do is extend this to apply to several concepts such as User Stories, Sprints, Releases (and sometimes Check-Ins). During project kick-off I’ll usually sit down with the team and go through an exercise of creating DoD’s for each of these concepts (Stories/Sprints/Releases). We’ll usually start by just brainstorming a bunch of activities that could end up in these various DoD’s. Here’s some examples: Code Reviews StyleCop FxCop User Manuals Updated Architecture Docs Updated Tested by QA Tested by UAT Installers Created Support Knowledge Base Updated Deployment Instructions (for Ops) written Automated Unit Tests Run Automated Integration Tests Run Then we start by arranging these activities into the place they occur today (e.g. Do you do UAT testing only once per release? every sprint? every feature?). If the team was previously Waterfall most of these activities probably end up in the Release DoD. An extremely mature agile team would probably have most of these activities in the DoD for the User Stories (because an extremely mature agile team will probably do continuous deployment and release every story). So what we need to do as a team, is work to move these activities from their current home (Release DoD) down into the Sprint DoD and eventually into the User Story DoD (and maybe into the lower-level Check-In DoD if we decide to use that). We don’t have to move them all down to User Story immediately, but as a team we figure out what we think we’re capable of moving down to the Sprint cycle, and Story cycle immediately, and that becomes our starting DoD’s. Over time the team makes an effort to continue moving activities down from Release->Sprint->Story as they become more agile and more mature. I try to encourage them to envision a world in which they deploy to production as each User Story is completed. They would need to be updating User Manuals, creating installers, doing UAT testing (typical Release cycle activities) on every single User Story. They may never actually reach that point, but they should envision that, and strive to keep driving the activities down closer to the User Story cycle s they mature. This is a great technique to give a team an easy-to-follow roadmap to mature their agile practices over time. Sure there’s other aspects to maturity outside of this, but it’s a great technique, that’s easy to visualize, to drive agility into the team. Just keep moving those activities (aka “gates”) down the board from Release->Sprint->Story. I’ll try to give an example of what a recent client of mine had for their DoD’s (this is from memory, so probably not 100% accurate): Release Create/Update deployment Instructions For Ops Instructional Videos Updated Run manual regression test suite UAT Testing In this case that meant deploying to an environment shared across the enterprise that mirrored production and asking other business groups to test their own apps to ensure we didn’t break anything outside our system Sprint Deploy to UAT Environment But not necessarily actually request UAT testing occur User Guides updated Sprint Features Video Created In this case we decided to create a video each sprint showing off the progress (video version of Sprint Demo) User Story Manual Test scripts developed and run Tested by BA Deployed in shared QA environment Using automated deployment process Peer Code Review Code Check-In Compiled (warning-free) Passes StyleCop Passes FxCop Create installer packages Run Automated Tests Run Automated Integration Tests PS – One of my clients had a great question when we went through this activity. They said that if a Sprint is by definition done when the end-date rolls around (time-boxed), isn’t a DoD on a sprint meaningless – it’s done on the end-date regardless of whether those other activities are complete or not? My answer is that while that statement is true – the sprint is done regardless when the end date rolls around – if the DoD activities haven’t been completed I would consider the Sprint a failure (similar to not completing what was committed/planned – failure may be too strong a word but you get the idea). In the Retrospective that will become an agenda item to discuss and understand why we weren’t able to complete the activities we agreed would need to be completed each Sprint.

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• What Counts for A DBA: Observant

  - by drsql

  When walking up to the building where I work, I can see CCTV cameras placed here and there for monitoring access to the building. We are required to wear authorization badges which could be checked at any time. Do we have enemies?  Of course! No one is 100% safe; even if your life is a fairy tale, there is always a witch with an apple waiting to snack you into a thousand years of slumber (or at least so I recollect from elementary school.) Even Little Bo Peep had to keep a wary lookout.    We nerdy types (or maybe it was just me?) generally learned on the school playground to keep an eye open for unprovoked attack from simpler, but more muscular souls, and take steps to avoid messy confrontations well in advance. After we’d apprehensively negotiated adulthood with varying degrees of success, these skills of watching for danger, and avoiding it,  translated quite well to the technical careers so many of us were destined for. And nowhere else is this talent for watching out for irrational malevolence so appropriate as in a career as a production DBA.   It isn’t always active malevolence that the DBA needs to watch out for, but the even scarier quirks of common humanity.  A large number of the issues that occur in the enterprise happen just randomly or even just one time ever in a spurious manner, like in the case where a person decided to download the entire MSDN library of software, cross join every non-indexed billion row table together, and simultaneously stream the HD feed of 5 different sporting events, making the network access slow while the corporate online sales just started. The decent DBA team, like the going, gets tough under such circumstances. They spring into action, checking all of the sources of active information, observes the issue is no longer happening now, figures that either it wasn’t the database’s fault and that the reboot of the whatever device on the network fixed the problem.  This sort of reactive support is good, and will be the initial reaction of even excellent DBAs, but it is not the end of the story if you really want to know what happened and avoid getting called again when it isn’t even your fault.   When fires start raging within the corporate software forest, the DBA’s instinct is to actively find a way to douse the flames and get back to having no one in the company have any idea who they are.  Even better for them is to find a way of killing a potential problem while the fires are small, long before they can be classified as raging. The observant DBA will have already been monitoring the server environment for months in advance.  Most troubles, such as disk space and security intrusions, can be predicted and dealt with by alerting systems, whereas other trouble can come out of the blue and requires a skill of observing ongoing conditions and noticing inexplicable changes that could signal an emerging problem.  You can’t automate the DBA, because the bankable skill of a DBA is in detecting the early signs of unexpected problems, and working out how to deal with them before anyone else notices them.    To achieve this, the DBA will check the situation as it is currently happening,  and in many cases is likely to have been the person who submitted the problem to the level 1 support person in the first place, just to let the support team know of impending issues (always well received, I tell you what!). Database and host computer settings, configurations, and even critical data might be profiled and captured for later comparisons. He’ll use Monitoring tools, built-in, commercial (Not to be too crassly commercial or anything, but there is one such tool is SQL Monitor) and lots of homebrew monitoring tools to monitor for problems and changes in the server environment.   You will know that you have it right when a support call comes in and you can look at your monitoring tools and quickly respond that “response time is well within the normal range, the query that supports the failing interface works perfectly and has actually only been called 67% as often as normal, so I am more than willing to help diagnose the problem, but it isn’t the database server’s fault and is probably a client or networking slowdown causing the interface to be used less frequently than normal.” And that is the best thing for any DBA to observe…

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• [AS3/C#] Byte encryption ( DES-CBC zero pad )

  - by mark_dj

  Hi there, Currently writing my own AMF TcpSocketServer. Everything works good so far i can send and recieve objects and i use some serialization/deserialization code. Now i started working on the encryption code and i am not so familiar with this stuff. I work with bytes , is DES-CBC a good way to encrypt this stuff? Or are there other more performant/secure ways to send my data? Note that performance is a must :). When i call: ReadAmf3Object with the decrypter specified i get an: InvalidOperationException thrown by my ReadAmf3Object function when i read out the first byte the Amf3TypeCode isn't specified ( they range from 0 to 16 i believe (Bool, String, Int, DateTime, etc) ). I got Typecodes varying from 97 to 254? Anyone knows whats going wrong? I think it has something to do with the encryption part. Since the deserializer works fine w/o the encryption. I am using the right padding/mode/key? I used: http://code.google.com/p/as3crypto/ as as3 encryption/decryption library. And i wrote an Async tcp server with some abuse of the threadpool ;) Anyway here some code: C# crypter initalization code System.Security.Cryptography.DESCryptoServiceProvider crypter = new DESCryptoServiceProvider(); crypter.Padding = PaddingMode.Zeros; crypter.Mode = CipherMode.CBC; crypter.Key = Encoding.ASCII.GetBytes("TESTTEST"); AS3 private static var _KEY:ByteArray = Hex.toArray(Hex.fromString("TESTTEST")); private static var _TYPE:String = "des-cbc"; public static function encrypt(array:ByteArray):ByteArray { var pad:IPad = new NullPad; var mode:ICipher = Crypto.getCipher(_TYPE, _KEY, pad); pad.setBlockSize(mode.getBlockSize()); mode.encrypt(array); return array; } public static function decrypt(array:ByteArray):ByteArray { var pad:IPad = new NullPad; var mode:ICipher = Crypto.getCipher(_TYPE, _KEY, pad); pad.setBlockSize(mode.getBlockSize()); mode.decrypt(array); return array; } C# read/unserialize/decrypt code public override object Read(int length) { object d; using (MemoryStream stream = new MemoryStream()) { stream.Write(this._readBuffer, 0, length); stream.Position = 0; if (this.Decrypter != null) { using (CryptoStream c = new CryptoStream(stream, this.Decrypter, CryptoStreamMode.Read)) using (AmfReader reader = new AmfReader(c)) { d = reader.ReadAmf3Object(); } } else { using (AmfReader reader = new AmfReader(stream)) { d = reader.ReadAmf3Object(); } } } return d; }

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• ZPL II Extended Characters

  - by Mauro

  I'm trying to print extended code page 850 characters using ZPL II to a Zebra S4M. Whenever one of the extended characters I.E. ASCII value 127 is used I get a box of varying shades of grey instead of the actual value. I'm trying to print ± and ° (ALT+0177 and ALT+0176). I suspect its the RawPrinterHelper I am trying to use (as downloaded from MS, and another from CodeProject) however I cant see where the character codes are going wrong. Weirdly, printing direct from Notepad renders the correct characters, which leads me to believe it is a problem with the raw printer helper class. I am not tied to using the Raw Printer Helper class so if there is a better way of doing it, I am more than happy to see them. SAMPLE ZPLII Without escaped chars ^XA ^FO30,200^AD^FH,18,10^FD35 ± 2 ° ^FS ^FS ^XZ With escaped chars (tried both upper and lower case) ^XA ^FO30,200^AD^FH,18,10^FD35 _b0 2 _b1 ^FS ^FS ^XZ Raw Printer Helper [StructLayout(LayoutKind.Sequential)] public struct DOCINFO { [MarshalAs(UnmanagedType.LPWStr)] public string printerDocumentName; [MarshalAs(UnmanagedType.LPWStr)] public string pOutputFile; [MarshalAs(UnmanagedType.LPWStr)] public string printerDocumentDataType; } public class RawPrinter { [ DllImport("winspool.drv", CharSet = CharSet.Unicode, ExactSpelling = false, CallingConvention = CallingConvention.StdCall)] public static extern long OpenPrinter(string pPrinterName, ref IntPtr phPrinter, int pDefault); [ DllImport("winspool.drv", CharSet = CharSet.Unicode, ExactSpelling = false, CallingConvention = CallingConvention.StdCall)] public static extern long StartDocPrinter(IntPtr hPrinter, int Level, ref DOCINFO pDocInfo); [ DllImport("winspool.drv", CharSet = CharSet.Unicode, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)] public static extern long StartPagePrinter(IntPtr hPrinter); [ DllImport("winspool.drv", CharSet = CharSet.Ansi, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)] public static extern long WritePrinter(IntPtr hPrinter, string data, int buf, ref int pcWritten); [ DllImport("winspool.drv", CharSet = CharSet.Unicode, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)] public static extern long EndPagePrinter(IntPtr hPrinter); [ DllImport("winspool.drv", CharSet = CharSet.Unicode, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)] public static extern long EndDocPrinter(IntPtr hPrinter); [ DllImport("winspool.drv", CharSet = CharSet.Unicode, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)] public static extern long ClosePrinter(IntPtr hPrinter); public static void SendToPrinter(string printerJobName, string rawStringToSendToThePrinter, string printerNameAsDescribedByPrintManager) { IntPtr handleForTheOpenPrinter = new IntPtr(); DOCINFO documentInformation = new DOCINFO(); int printerBytesWritten = 0; documentInformation.printerDocumentName = printerJobName; documentInformation.printerDocumentDataType = "RAW"; OpenPrinter(printerNameAsDescribedByPrintManager, ref handleForTheOpenPrinter, 0); StartDocPrinter(handleForTheOpenPrinter, 1, ref documentInformation); StartPagePrinter(handleForTheOpenPrinter); WritePrinter(handleForTheOpenPrinter, rawStringToSendToThePrinter, rawStringToSendToThePrinter.Length, ref printerBytesWritten); EndPagePrinter(handleForTheOpenPrinter); EndDocPrinter(handleForTheOpenPrinter); ClosePrinter(handleForTheOpenPrinter); } }

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• Entity Framework won't SaveChanges on new entity with two-level relationship

  - by Tim Rourke

  I'm building an ASP.NET MVC site using the ADO.NET Entity Framework. I have an entity model that includes these entities, associated by foreign keys: Report(ID, Date, Heading, Report_Type_ID, etc.) SubReport(ID, ReportText, etc.) - one-to-one relationship with Report. ReportSource(ID, Name, Description) - one-to-many relationship with Sub_Report. ReportSourceType(ID, Name, Description) - one-to-many relationship with ReportSource. Contact (ID, Name, Address, etc.) - one-to-one relationship with Report_Source. There is a Create.aspx page for each type of SubReport. The post event method returns a new Sub_Report entity. Before, in my post method, I followed this process: Set the properties for a new Report entity from the page's fields. Set the SubReport entity's specific properties from the page's fields. Set the SubReport entity's Report to the new Report entity created in 1. Given an ID provided by the page, look up the ReportSource and set the Sub_Report entity's ReportSource to the found entity. SaveChanges. This workflow succeeded just fine for a couple of weeks. Then last week something changed and it doesn't work any more. Now instead of the save operation, I get this Exception: UpdateException: "Entities in 'DIR2_5Entities.ReportSourceSet' participate in the 'FK_ReportSources_ReportSourceTypes' relationship. 0 related 'ReportSourceTypes' were found. 1 'Report_Source_Types' is expected." The debug visualizer shows the following: The SubReport's ReportSource is set and loaded, and all of its properties are correct. The Report_Source has a valid ReportSourceType entity attached. In SQL Profiler the prepared SQL statement looks OK. Can anybody point me to what obvious thing I'm missing? TIA Notes: The Report and SubReport are always new entities in this case. The Report entity contains properties common to many types of reports and is used for generic queries. SubReports are specific reports with extra parameters varying by type. There is actually a different entity set for each type of SubReport, but this question applies to all of them, so I use SubReport as a simplified example.

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• Linq To Sql Concat() dropping fields in created TSQL

  - by user191468

  This is strange. I am moving a stored proc to a service. The TSQL unions multiple selects. To replicate this I created multiple queries resulting in a common new concrete type. Then I issue a return result.ToString(); and the resulting SQL selects have varying numbers of columns specified thus causing an MSSQL Msg 205... using (var db = GetDb()) { var fundInv = from f in db.funds select new Investments { Company = f.company, FullName = f.fullname, Admin = f.admin, Fund = f.fund1, FundCode = f.fundcode, Source = STR_FUNDS, IsPortfolio = false, IsActive = f.active, Strategy = f.strategy, SubStrategy = f.substrategy, AltStrategy = f.altstrategy, AltSubStrategy = f.altsubstrategy, Region = f.region, AltRegion = f.altregion, UseAlternate = f.usealt, ClassesAllowed = f.classallowed }; var stocksInv = from s in db.stocks where !fundInv.Select(f => f.Company).Contains(s.vehcode) select new Investments { Company = s.company, FullName = s.issuer, Admin = STR_PRS, Fund = s.shortname, FundCode = s.vehcode, Source = STR_STOCK, IsPortfolio = false, IsActive = (s.inactive == null), Strategy = s.style, SubStrategy = s.substyle, AltStrategy = s.altstyle, AltSubStrategy = s.altsubsty, Region = s.geography, AltRegion = s.altgeo, UseAlternate = s.usealt, ClassesAllowed = STR_GENERIC }; var bondsInv = from oi in db.bonds where !fundInv.Select(f => f.Company).Contains(oi.vehcode) select new Investments { Company = string.Empty, FullName = oi.issue, Admin = STR_PRS1, Fund = oi.issue, FundCode = oi.vehcode, Source = STR_BONDS, IsPortfolio = false, IsActive = oi.closed, Strategy = STR_OTH, SubStrategy = STR_OTH, AltStrategy = STR_OTH, AltSubStrategy = STR_OTH, Region = STR_OTH, AltRegion = STR_OTH, UseAlternate = false, ClassesAllowed = STR_GENERIC }; return (fundInv.Concat(stocksInv).Concat(bondsInv)).ToList(); } The code above results in a complex select statement where each "table" above has different column count. (see SQL below) I've been trying a few things but no change yet. Ideas are welcome. SELECT [t6].[company] AS [Company], [t6].[fullname] AS [FullName], [t6].[admin] AS [Admin], [t6].[fund] AS [Fund], [t6].[fundcode] AS [FundCode], [t6].[value] AS [Source], [t6].[value2] AS [IsPortfolio], [t6].[active] AS [IsActive], [t6].[strategy] AS [Strategy], [t6].[substrategy] AS [SubStrategy], [t6].[altstrategy] AS [AltStrategy], [t6].[altsubstrategy] AS [AltSubStrategy], [t6].[region] AS [Region], [t6].[altregion] AS [AltRegion], [t6].[usealt] AS [UseAlternate], [t6].[classallowed] AS [ClassesAllowed] FROM ( SELECT [t3].[company], [t3].[fullname], [t3].[admin], [t3].[fund], [t3].[fundcode], [t3].[value], [t3].[value2], [t3].[active], [t3].[strategy], [t3].[substrategy], [t3].[altstrategy], [t3].[altsubstrategy], [t3].[region], [t3].[altregion], [t3].[usealt], [t3].[classallowed] FROM ( SELECT [t0].[company], [t0].[fullname], [t0].[admin], [t0].[fund], [t0].[fundcode], @p0 AS [value], [t0].[active], [t0].[strategy], [t0].[substrategy], [t0].[altstrategy], [t0].[altsubstrategy], [t0].[region], [t0].[altregion], [t0].[usealt], [t0].[classallowed] FROM [zInvest].[funds] AS [t0] UNION ALL SELECT [t1].[company], [t1].[issuer], @p6 AS [value], [t1].[shortname], [t1].[vehcode], @p7 AS [value2], @p8 AS [value3], (CASE WHEN [t1].[inactive] IS NULL THEN 1 ELSE 0 END) AS [value5], [t1].[style], [t1].[substyle], [t1].[altstyle], [t1].[altsubsty], [t1].[geography], [t1].[altgeo], [t1].[usealt], @p10 AS [value6] FROM [zBank].[stocks] AS [t1] WHERE (NOT (EXISTS( SELECT NULL AS [EMPTY] FROM [zInvest].[funds] AS [t2] WHERE [t2].[company] = [t1].[vehcode] ))) AND ([t1].[vehcode] <> @p2) AND (SUBSTRING([t1].[vehcode], @p3 + 1, @p4) <> @p5) ) AS [t3] UNION ALL SELECT @p11 AS [value], [t4].[issue], @p12 AS [value2], [t4].[vehcode], @p13 AS [value3], @p14 AS [value4], [t4].[closed], @p16 AS [value6], @p17 AS [value7] FROM [zMut].[bonds] AS [t4] WHERE NOT (EXISTS( SELECT NULL AS [EMPTY] FROM [zInvest].[funds] AS [t5] WHERE [t5].[company] = [t4].[vehcode] )) ) AS [t6]

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• DynamicMethod for ConstructorInfo.Invoke, what do I need to consider?

  - by Lasse V. Karlsen

  My question is this: If I'm going to build a DynamicMethod object, corresponding to a ConstructorInfo.Invoke call, what types of IL do I need to implement in order to cope with all (or most) types of arguments, when I can guarantee that the right type and number of arguments is going to be passed in before I make the call? Background I am on my 3rd iteration of my IoC container, and currently doing some profiling to figure out if there are any areas where I can easily shave off large amounts of time being used. One thing I noticed is that when resolving to a concrete type, ultimately I end up with a constructor being called, using ConstructorInfo.Invoke, passing in an array of arguments that I've worked out. What I noticed is that the invoke method has quite a bit of overhead, and I'm wondering if most of this is just different implementations of the same checks I do. For instance, due to the constructor matching code I have, to find a matching constructor for the predefined parameter names, types, and values that I have passed in, there's no way this particular invoke call will not end up with something it should be able to cope with, like the correct number of arguments, in the right order, of the right type, and with appropriate values. When doing a profiling session containing a million calls to my resolve method, and then replacing it with a DynamicMethod implementation that mimics the Invoke call, the profiling timings was like this: ConstructorInfo.Invoke: 1973ms DynamicMethod: 93ms This accounts for around 20% of the total runtime of this profiling application. In other words, by replacing the ConstructorInfo.Invoke call with a DynamicMethod that does the same, I am able to shave off 20% runtime when dealing with basic factory-scoped services (ie. all resolution calls end up with a constructor call). I think this is fairly substantial, and warrants a closer look at how much work it would be to build a stable DynamicMethod generator for constructors in this context. So, the dynamic method would take in an object array, and return the constructed object, and I already know the ConstructorInfo object in question. Therefore, it looks like the dynamic method would be made up of the following IL: l001: ldarg.0 ; the object array containing the arguments l002: ldc.i4.0 ; the index of the first argument l003: ldelem.ref ; get the value of the first argument l004: castclass T ; cast to the right type of argument (only if not "Object") (repeat l001-l004 for all parameters, l004 only for non-Object types, varying l002 constant from 0 and up for each index) l005: newobj ci ; call the constructor l006: ret Is there anything else I need to consider? Note that I'm aware that creating dynamic methods will probably not be available when running the application in "reduced access mode" (sometimes the brain just won't give up those terms), but in that case I can easily detect that and just calling the original constructor as before, with the overhead and all.

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• Programmatically specifying Django model attributes

  - by mojbro

  Hi! I would like to add attributes to a Django models programmatically, at run time. For instance, lets say I have a Car model class and want to add one price attribute (database column) per currency, given a list of currencies. What is the best way to do this? I had an approach that I thought would work, but it didn't exactly. This is how I tried doing it, using the car example above: from django.db import models class Car(models.Model): name = models.CharField(max_length=50) currencies = ['EUR', 'USD'] for currency in currencies: Car.add_to_class('price_%s' % currency.lower(), models.IntegerField()) This does seem to work pretty well at first sight: $ ./manage.py syncdb Creating table shop_car $ ./manage.py dbshell shop=# \d shop_car Table "public.shop_car" Column | Type | Modifiers -----------+-----------------------+------------------------------------------------------- id | integer | not null default nextval('shop_car_id_seq'::regclass) name | character varying(50) | not null price_eur | integer | not null price_usd | integer | not null Indexes: "shop_car_pkey" PRIMARY KEY, btree (id) But when I try to create a new Car, it doesn't really work anymore: >>> from shop.models import Car >>> mycar = Car(name='VW Jetta', price_eur=100, price_usd=130) >>> mycar <Car: Car object> >>> mycar.save() Traceback (most recent call last): File "<console>", line 1, in <module> File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/django/db/models/base.py", line 410, in save self.save_base(force_insert=force_insert, force_update=force_update) File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/django/db/models/base.py", line 495, in save_base result = manager._insert(values, return_id=update_pk) File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/django/db/models/manager.py", line 177, in _insert return insert_query(self.model, values, **kwargs) File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/django/db/models/query.py", line 1087, in insert_query return query.execute_sql(return_id) File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/django/db/models/sql/subqueries.py", line 320, in execute_sql cursor = super(InsertQuery, self).execute_sql(None) File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/django/db/models/sql/query.py", line 2369, in execute_sql cursor.execute(sql, params) File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/django/db/backends/util.py", line 19, in execute return self.cursor.execute(sql, params) ProgrammingError: column "price_eur" specified more than once LINE 1: ...NTO "shop_car" ("name", "price_eur", "price_usd", "price_eur... ^

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• ASP.Net MVC Exception Logging combined with Error Handling

  - by Saajid Ismail

  Hi. I am looking for a simple solution to do Exception Logging combined with Error Handling in my ASP.Net MVC 1.0 application. I've read lots of articles, including Questions posted here on StackOverflow, which all provide varying solutions for different situations. I am still unable to come up with a solution that suits my needs. Here are my requirements: To be able to use the [HandleError] attribute (or something equivalent) on my Controller, to handle all exceptions that could be thrown from any of the Actions or Views. This should handle all exceptions that were not handled specifically on any of the Actions (as described in point 2). I would like to be able to specify which View a user must be redirected to in error cases, for all actions in the Controller. I want to be able to specify the [HandleError] attribute (or something equivalent) at the top of specific Actions to catch specific exceptions and redirect users to a View appropriate to the exception. All other exceptions must still be handled by the [HandleError] attribute on the Controller. In both cases above, I want the exceptions to be logged using log4net (or any other logging library). How do I go about achieving the above? I've read about making all my Controllers inherit from a base controller which overrides the OnException method, and wherein I do my logging. However this will mess around with redirecting users to the appropriate Views, or make it messy. I've read about writing my own Filter Action which implements IExceptionFilter to handle this, but this will conflict with the [HandleError] attribute. So far, my thoughts are that the best solution is to write my own attribute that inherits from HandleErrorAttribute. That way I get all the functionality of [HandleError], and can add my own log4net logging. The solution is as follows: public class HandleErrorsAttribute: HandleErrorAttribute { private log4net.ILog log = log4net.LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType); public override void OnException(ExceptionContext filterContext) { if (filterContext.Exception != null) { log.Error("Error in Controller", filterContext.Exception); } base.OnException(filterContext); } } Will the above code work for my requirements? If not, what solution does fulfill my requirements?

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• Modeling distribution of performance measurements

  - by peterchen

  How would you mathematically model the distribution of repeated real life performance measurements - "Real life" meaning you are not just looping over the code in question, but it is just a short snippet within a large application running in a typical user scenario? My experience shows that you usually have a peak around the average execution time that can be modeled adequately with a Gaussian distribution. In addition, there's a "long tail" containing outliers - often with a multiple of the average time. (The behavior is understandable considering the factors contributing to first execution penalty). My goal is to model aggregate values that reasonably reflect this, and can be calculated from aggregate values (like for the Gaussian, calculate mu and sigma from N, sum of values and sum of squares). In other terms, number of repetitions is unlimited, but memory and calculation requirements should be minimized. A normal Gaussian distribution can't model the long tail appropriately and will have the average biased strongly even by a very small percentage of outliers. I am looking for ideas, especially if this has been attempted/analysed before. I've checked various distributions models, and I think I could work out something, but my statistics is rusty and I might end up with an overblown solution. Oh, a complete shrink-wrapped solution would be fine, too ;) Other aspects / ideas: Sometimes you get "two humps" distributions, which would be acceptable in my scenario with a single mu/sigma covering both, but ideally would be identified separately. Extrapolating this, another approach would be a "floating probability density calculation" that uses only a limited buffer and adjusts automatically to the range (due to the long tail, bins may not be spaced evenly) - haven't found anything, but with some assumptions about the distribution it should be possible in principle. Why (since it was asked) - For a complex process we need to make guarantees such as "only 0.1% of runs exceed a limit of 3 seconds, and the average processing time is 2.8 seconds". The performance of an isolated piece of code can be very different from a normal run-time environment involving varying levels of disk and network access, background services, scheduled events that occur within a day, etc. This can be solved trivially by accumulating all data. However, to accumulate this data in production, the data produced needs to be limited. For analysis of isolated pieces of code, a gaussian deviation plus first run penalty is ok. That doesn't work anymore for the distributions found above. [edit] I've already got very good answers (and finally - maybe - some time to work on this). I'm starting a bounty to look for more input / ideas.

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• Is One Tool or a Suite of Tools Better for Scrum?

  - by Rob Wells

  G'day, Edit: We've been using Scrum very successfully for several years on several projects of varying sizes. In fact, our team developed the successful iPlayer project for the BBC using a classical Scrum approach. After using various combinations of tools, some high-tech, some low-tech, across these projects we now wish to try adopting a suitable tool suite. Our manager is to some extent attempting to force the adoption of a single suite of tools for Scrum. I've looked at the SO question "Best Scrum tools" and most people seem to recommend either: a suite of low-tech solutions, e.g. whiteboards, post-its, index cards, etc., or a monolithic tool that tries to satisfy as much as possible of the process, e.g. Agilo, Mingle, ScrumWorks, Target Process, etc. Our team is currently evaluating several different Scrum tools. However, we are looking at selecting a single, monolithic tool, e.g. Agilo. All of the "one-stop" solutions have their strengths and weaknesses with the serious enterprise type solutions being the best sort of fit. But all have some short comings. After reading the paper "Peer Code Review: An Agile Process" over at SmartBear I started wondering if we were trying to force adoption of a tool on a "best fit" basis. I think you can take a couple of reference artefacts of the Scrum development process, say user stories, epics and themes, and the code base which must use a well-known SCM, e.g. SVN, Hg, etc. Then if we take that as the common reference points for the tools employed then we would be able to use a group of tools to handle the different aspects of the Scrum process rather than try forcing a fit of a single tool would is a bit like forcing a square peg into the round hole. In this way, providing you've agreed your common reference points, you can use several tools, each performing their role better than a could be done by a single component in a monolithic tool suite. Is this a more sensible approach? Are the two reference points I mentioned above suitable, or is their a better choice of points where the tools would meet? cheers,

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• Fixed point math in c#?

  - by x4000

  Hi there, I was wondering if anyone here knows of any good resources for fixed point math in c#? I've seen things like this (http://2ddev.72dpiarmy.com/viewtopic.php?id=156) and this (http://stackoverflow.com/questions/79677/whats-the-best-way-to-do-fixed-point-math), and a number of discussions about whether decimal is really fixed point or actually floating point (update: responders have confirmed that it's definitely floating point), but I haven't seen a solid C# library for things like calculating cosine and sine. My needs are simple -- I need the basic operators, plus cosine, sine, arctan2, PI... I think that's about it. Maybe sqrt. I'm programming a 2D RTS game, which I have largely working, but the unit movement when using floating-point math (doubles) has very small inaccuracies over time (10-30 minutes) across multiple machines, leading to desyncs. This is presently only between a 32 bit OS and a 64 bit OS, all the 32 bit machines seem to stay in sync without issue, which is what makes me think this is a floating point issue. I was aware from this as a possible issue from the outset, and so have limited my use of non-integer position math as much as possible, but for smooth diagonal movement at varying speeds I'm calculating the angle between points in radians, then getting the x and y components of movement with sin and cos. That's the main issue. I'm also doing some calculations for line segment intersections, line-circle intersections, circle-rect intersections, etc, that also probably need to move from floating-point to fixed-point to avoid cross-machine issues. If there's something open source in Java or VB or another comparable language, I could probably convert the code for my uses. The main priority for me is accuracy, although I'd like as little speed loss over present performance as possible. This whole fixed point math thing is very new to me, and I'm surprised by how little practical information on it there is on google -- most stuff seems to be either theory or dense C++ header files. Anything you could do to point me in the right direction is much appreciated; if I can get this working, I plan to open-source the math functions I put together so that there will be a resource for other C# programmers out there. UPDATE: I could definitely make a cosine/sine lookup table work for my purposes, but I don't think that would work for arctan2, since I'd need to generate a table with about 64,000x64,000 entries (yikes). If you know any programmatic explanations of efficient ways to calculate things like arctan2, that would be awesome. My math background is all right, but the advanced formulas and traditional math notation are very difficult for me to translate into code.

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• Rush Hour - Solving the game

  - by Rubys

  Rush Hour if you're not familiar with it, the game consists of a collection of cars of varying sizes, set either horizontally or vertically, on a NxM grid that has a single exit. Each car can move forward/backward in the directions it's set in, as long as another car is not blocking it. You can never change the direction of a car. There is one special car, usually it's the red one. It's set in the same row that the exit is in, and the objective of the game is to find a series of moves (a move - moving a car N steps back or forward) that will allow the red car to drive out of the maze. I've been trying to think how to solve this problem computationally, and I can really not think of any good solution. I came up with a few: Backtracking. This is pretty simple - Recursion and some more recursion until you find the answer. However, each car can be moved a few different ways, and in each game state a few cars can be moved, and the resulting game tree will be HUGE. Some sort of constraint algorithm that will take into account what needs to be moved, and work recursively somehow. This is a very rough idea, but it is an idea. Graphs? Model the game states as a graph and apply some sort of variation on a coloring algorithm, to resolve dependencies? Again, this is a very rough idea. A friend suggested genetic algorithms. This is sort of possible but not easily. I can't think of a good way to make an evaluation function, and without that we've got nothing. So the question is - How to create a program that takes a grid and the vehicle layout, and outputs a series of steps needed to get the red car out? Sub-issues: Finding some solution. Finding an optimal solution (minimal number of moves) Evaluating how good a current state is Example: How can you move the cars in this setting, so that the red car can "exit" the maze through the exit on the right?

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• CSS Transform offset varies with text length

  - by Mr. Polywhirl

  I have set up a demo that has 5 floating <div>s with rotated text of varying length. I am wondering if there is a way to have a CSS class that can handle centering of all text regardless of length. At the moment I have to create a class for each length of characters in my stylesheet. This could get too messy. I have also noticed that the offsets get screwd up is I increase or decrease the size of the wrapping <div>. I will be adding these classes to divs through jQuery, but I still have to set up each class for cross-browser compatibility. .transform3 { -webkit-transform-origin: 65% 100%; -moz-transform-origin: 65% 100%; -ms-transform-origin: 65% 100%; -o-transform-origin: 65% 100%; transform-origin: 65% 100%; } .transform4 { -webkit-transform-origin: 70% 110%; -moz-transform-origin: 70% 110%; -ms-transform-origin: 70% 110%; -o-transform-origin: 70% 110%; transform-origin: 70% 110%; } .transform5 { -webkit-transform-origin: 80% 120%; -moz-transform-origin: 80% 120%; -ms-transform-origin: 80% 120%; -o-transform-origin: 80% 120%; transform-origin: 80% 120%; } .transform6 { -webkit-transform-origin: 85% 136%; -moz-transform-origin: 85% 136%; -ms-transform-origin: 85% 136%; -o-transform-origin: 85% 136%; transform-origin: 85% 136%; } .transform7 { -webkit-transform-origin: 90% 150%; -moz-transform-origin: 90% 150%; -ms-transform-origin: 90% 150%; -o-transform-origin: 90% 150%; transform-origin: 90% 150%; } Note: The offset values I set were eye-balled. Update Although I would like this handled with a stylesheet, I believe that I will have to calculate the transformations of the CSS in JavaScript. I have created the following demo to demonstrate dynamic transformations. In this demo, the user can adjust the font-size of the .v_text class and as long as the length of the text does not exceed the .v_text_wrapper height, the text should be vertically aligned in the center, but be aware that I have to adjust the magicOffset value. Well, I just noticed that this does not work in iOS...

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• VS2008: File creation fails randomly in unit testing?

  - by Tim

  I'm working on implementing a reasonably simple XML serializer/deserializer (log file parser) application in C# .NET with VS 2008. I have about 50 unit tests right now for various parts of the code (mostly for the various serialization operations), and some of them seem to be failing mostly at random when they deal with file I/O. The way the tests are structured is that in the test setup method, I create a new empty file at a certain predetermined location, and close the stream I get back. Then I run some basic tests on the file (varying by what exactly is under test). In the cleanup method, I delete the file again. A large portion (usually 30 or more, though the number varies run to run) of my unit tests will fail at the initialize method, claiming they can't access the file I'm trying to create. I can't pin down the exact reason, since a test that will work one run fails the next; they all succeed when run individually. What's the problem here? Why can't I access this file across multiple unit tests? Relevant methods for a unit test that will fail some of the time: [TestInitialize()] public void LogFileTestInitialize() { this.testFolder = System.Environment.GetFolderPath( System.Environment.SpecialFolder.LocalApplicationData ); this.testPath = this.testFolder + "\\empty.lfp"; System.IO.File.Create(this.testPath); } [TestMethod()] public void LogFileConstructorTest() { string filePath = this.testPath; LogFile target = new LogFile(filePath); Assert.AreNotEqual(null, target); Assert.AreEqual(this.testPath, target.filePath); Assert.AreEqual("empty.lfp", target.fileName); Assert.AreEqual(this.testFolder + "\\empty.lfp.lfpdat", target.metaPath); } [TestCleanup()] public void LogFileTestCleanup() { System.IO.File.Delete(this.testPath); } And the LogFile() constructor: public LogFile(String filePath) { this.entries = new List<Entry>(); this.filePath = filePath; this.metaPath = filePath + ".lfpdat"; this.fileName = filePath.Substring(filePath.LastIndexOf("\\") + 1); } The precise error message: Initialization method LogFileParserTester.LogFileTest.LogFileTestInitialize threw exception. System.IO.IOException: System.IO.IOException: The process cannot access the file 'C:\Users\<user>\AppData\Local\empty.lfp' because it is being used by another process..

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• How to optimize my PostgreSQL DB for prefix search?

  - by asmaier

  I have a table called "nodes" with roughly 1.7 million rows in my PostgreSQL db =#\d nodes Table "public.nodes" Column | Type | Modifiers --------+------------------------+----------- id | integer | not null title | character varying(256) | score | double precision | Indexes: "nodes_pkey" PRIMARY KEY, btree (id) I want to use information from that table for autocompletion of a search field, showing the user a list of the ten titles having the highest score fitting to his input. So I used this query (here searching for all titles starting with "s") =# explain analyze select title,score from nodes where title ilike 's%' order by score desc; QUERY PLAN ----------------------------------------------------------------------------------------------------------------------- Sort (cost=64177.92..64581.38 rows=161385 width=25) (actual time=4930.334..5047.321 rows=161264 loops=1) Sort Key: score Sort Method: external merge Disk: 5712kB -> Seq Scan on nodes (cost=0.00..46630.50 rows=161385 width=25) (actual time=0.611..4464.413 rows=161264 loops=1) Filter: ((title)::text ~~* 's%'::text) Total runtime: 5260.791 ms (6 rows) This was much to slow for using it with autocomplete. With some information from Using PostgreSQL in Web 2.0 Applications I was able to improve that with a special index =# create index title_idx on nodes using btree(lower(title) text_pattern_ops); =# explain analyze select title,score from nodes where lower(title) like lower('s%') order by score desc limit 10; QUERY PLAN ------------------------------------------------------------------------------------------------------------------------------------------ Limit (cost=18122.41..18122.43 rows=10 width=25) (actual time=1324.703..1324.708 rows=10 loops=1) -> Sort (cost=18122.41..18144.60 rows=8876 width=25) (actual time=1324.700..1324.702 rows=10 loops=1) Sort Key: score Sort Method: top-N heapsort Memory: 17kB -> Bitmap Heap Scan on nodes (cost=243.53..17930.60 rows=8876 width=25) (actual time=96.124..1227.203 rows=161264 loops=1) Filter: (lower((title)::text) ~~ 's%'::text) -> Bitmap Index Scan on title_idx (cost=0.00..241.31 rows=8876 width=0) (actual time=90.059..90.059 rows=161264 loops=1) Index Cond: ((lower((title)::text) ~>=~ 's'::text) AND (lower((title)::text) ~<~ 't'::text)) Total runtime: 1325.085 ms (9 rows) So this gave me a speedup of factor 4. But can this be further improved? What if I want to use '%s%' instead of 's%'? Do I have any chance of getting a decent performance with PostgreSQL in that case, too? Or should I better try a different solution (Lucene?, Sphinx?) for implementing my autocomplete feature?

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