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• How does throwing an ArgumentNullException help?

  - by Scott Whitlock

  Let's say I have a method: public void DoSomething(ISomeInterface someObject) { if(someObject == null) throw new ArgumentNullException("someObject"); someObject.DoThisOrThat(); } I've been trained to believe that throwing the ArgumentNullException is "correct" but an "Object reference not set to an instance of an object" error means I have a bug. Why? I know that if I was caching the reference to someObject and using it later, then it's better to check for nullity when passed in, and fail early. However, if I'm dereferencing it on the next line, why are we supposed to do the check? It's going to throw an exception one way or the other. Edit: It just occurred to me... does the fear of the dereferenced null come from a language like C++ that doesn't check for you (i.e. it just tries to execute some method at memory location zero + method offset)?

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• How do I determine the draw order in an isometric view flash game?

  - by Gajet

  This is for a flash game, with isometric view. I need to know how to sort object so that there is no need for z-buffer checking when drawing. This might seem easy but there is another restriction, a scene can have 10,000+ objects so the algorithm needs to be run in less than O(n^2). All objects are rectangular boxes, and there are 3-4 objects moving in the scene. What's the best way to do this? UPDATE in each tile there is only object (I mean objects can stack on top of each other). and we access to both map of Objects and Objects have their own position.

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• Four New Videos on ASP.NET MVC 2

  Microsoft?s Jon Galloway has recorded 4 new ?quick hit? videos to help you get up to speed on new features in ASP.NET MVC 2. Learn about HTML Encoding, Strongly Typed Helpers, Model Validation, and Template Customization in these newest videos.

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• Where to store shaders

  - by Mark Ingram

  I have an OpenGL renderer which has a Scene member variable. The Scene object can contain N SceneObjects. I use these SceneObjects for storing the vertex position and any transforms. My question is, where should shaders be stored in this arrangement? I guess they need to be in a central location because multiple objects can use the same shader. But then each object needs access to the shader because it needs to set attributes into the shader. Does anyone have any advice?

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• 3D/perspective Top down shooter bullet issues

  - by Tseng

  I'm developing a top-down shooter with multiple levels (ground for ground units, middle level for buildings, top level for air unity). The problem is the collision. Though I can make the collider box of a bullet be long enough to reach the ground (and collide with it), the real issue is optical. When the bullet is fired from a aircraft and collides with some object on the ground (building, ground unit) it will be optically offset due to the perspective camera, because it looks like the shot "by-passed" the target as seen below Is there any way to make the bullets collide perspectively correct? I'm using Unity3d Engine and it offers only simple colliders (box, sphere, cylinder, mesh and wheel), though I don't think a cone-formed collider would solve this issue. I'd need a (cheap) way to check if it's overlapping a destructible object? I thought of casting a ray from the camera through the bullet and if it hits something destructible, trigger an action, but that's quite punctual and maybe to performance heavy on certain number of bullets

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• Why isn't DSM for unstructured memory done today?

  - by sinned

  Ages ago, Djikstra invented IPC through mutexes which then somehow led to shared memory (SHM) in multics (which afaik had the necessary mmap first). Then computer networks came up and DSM (distributed SHM) was invented for IPC between computers. So DSM is basically a not prestructured memory region (like a SHM) that magically get's synchronized between computers without the applications programmer taking action. Implementations include Treadmarks (inofficially dead now) and CRL. But then someone thought this is not the right way to do it and invented Linda & tuplespaces. Current implementations include JavaSpaces and GigaSpaces. Here, you have to structure your data into tuples. Other ways to achieve similar effects may be the use of a relational database or a key-value-store like RIAK. Although someone might argue, I don't consider them as DSM since there is no coherent memory region where you can put data structures in as you like but have to structure your data which can be hard if it is continuous and administration like locking can not be done for hard coded parts (=tuples, ...). Why is there no DSM implementation today or am I just unable to find one?

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• What are the steps to grouping related classes into packages

  - by user2368481

  I've been googling this for some time, but what I haven't found are the clear steps needed to be taken to group related classes into packages in Java. In my case, I have about a number of .java files that I'd like to group into 3 packages according to the MVC pattern. One package for Model classes, one package for View classes and one package for Controller classes. I've identified which belong in what package, but not sure of the next step.

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• String contains trailing zeroes when converted from decimal [migrated]

  - by Locke

  I've run into an unusual quirk in a program I'm writing, and I was trying to figure out if anyone knew the cause. Note that fixing the issue is easy enough. I just can't figure out why it is happening in the first place. I have a WinForms program written in VB.NET that is displaying a subset of data. It contains a few labels that show numeric values (the .Text property of the labels are being assigned directly from the Decimal values). These numbers are being returned by a DLL I wrote in C#. The DLL calls a webservice which initially returns the values in question. It returns one as a string, the other as a decimal (I don't have any control over the webservice, I just consume it). The DLL assigns these to properties on an object (both of which are decimals) then returns that object back to the WinForm program that called the DLL. Obviously, there's a lot of other data being consumed from the webservice, but no other operations are happening which could modify these properties. So, the short version is: WinForm requests a new Foo from the DLL. DLL creates object Foo. DLL calls webservice, which returns SomeOtherFoo. //Both Foo.Bar1 and Foo.Bar2 are decimals Foo.Bar1 = decimal.Parse(SomeOtherFoo.Bar1); //SomeOtherFoo.Bar1 is a string equal to "2.9000" Foo.Bar2 = SomeOtherFoo.Bar2; //SomeOtherFoo.Bar2 is a decimal equal to 2.9D DLL returns Foo to WinForm. WinForm.lblMockLabelName1.Text = Foo.Bar1 //Inspecting Foo.Bar1 indicates my value is 2.9D WinForm.lblMockLabelName2.Text = Foo.Bar2 //Inspecting Foo.Bar2 also indicates I'm 2.9D So, what's the quirk? WinForm.lblMockLabelName1.Text displays as "2.9000", whereas WinForm.lblMockLabelname2.Text displays as "2.9". Now, everything I know about C# and VB indicates that the format of the string which was initially parsed into the decimal should have no bearing on the outcome of a later decimal.ToString() operation called on the same decimal. I would expect that decimal.Parse(someDecimalString).ToString() would return the string without any trailing zeroes. Everything I find online seems to corroborate this (there are countless Stack Overflow questions asking exactly the opposite...how to keep the formatting from the initial parsing). At the moment, I've just removed the trailing zeroes from the initial string that gets parsed, which has hidden the quirk. However, I'd love to know why it happens in the first place.

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• Orchestrating the Virtual Enterprise

  - by John Murphy

  During the American Industrial Revolution, the Ford Motor Company did it all. It turned raw materials into a showroom full of Model Ts. It owned a steel mill, a glass factory, and an automobile assembly line. The company was both self-sufficient and innovative and went on to become one of the largest and most profitable companies in the world. Nowadays, it's unusual for any business to follow this vertical integration model because its much harder to be best in class across such a wide a range of capabilities and services. Instead, businesses focus on their core competencies and outsource other business functions to specialized suppliers. They exchange vertical integration for collaboration. When done well, all parties benefit from this arrangement and the collaboration leads to the creation of an agile, lean and successful "virtual enterprise." Case in point: For Sun hardware, Oracle outsources most of its manufacturing and all of its logistics to third parties. These are vital activities, but ones where Oracle doesn't have a core competency, so we shift them to business partners who do. Within our enterprise, we always retain the core functions of product development, support, and most of the sales function, because that's what constitutes our core value to our customers. This is a perfect example of a virtual enterprise.  What are the implications of this? It means that we must exchange direct internal control for indirect external collaboration. This fundamentally changes the relative importance of different business processes, the boundaries of security and information sharing, and the relationship of the supply chain systems to the ERP. The challenge is that the systems required to support this virtual paradigm are still mired in "island enterprise" thinking. But help is at hand. Developments such as the Web, social networks, collaboration, and rules-based orchestration offer great potential to fundamentally re-architect supply chain systems to better support the virtual enterprise.  Supply Chain Management Systems in a Virtual Enterprise Historically enterprise software was constructed to automate the ERP - and then the supply chain systems extended the ERP. They were joined at the hip. In virtual enterprises, the supply chain system needs to be ERP agnostic, sitting above each of the ERPs that are distributed across the virtual enterprise - most of which are operating in other businesses. This is vital so that the supply chain system can manage the flow of material and the related information through the multiple enterprises. It has to have strong collaboration tools. It needs to be highly flexible. Users need to be able to see information that's coming from multiple sources and be able to react and respond to events across those sources.  Oracle Fusion Distributed Order Orchestration (DOO) is a perfect example of a supply chain system designed to operate in this virtual way. DOO embraces the idea that a company's fulfillment challenge is a distributed, multi-enterprise problem. It enables users to manage the process and the trading partners in a uniform way and deliver a consistent user experience while operating over a heterogeneous, virtual enterprise. This is a fundamental shift at the core of managing supply chains. It forces virtual enterprises to think architecturally about how best to construct their supply chain systems.  Case in point, almost everyone has ordered from Amazon.com at one time or another. Our orders are as likely to be fulfilled by third parties as they are by Amazon itself. To deliver the order promptly and efficiently, Amazon has to send it to the right fulfillment location and know the availability in that location. It needs to be able to track status of the fulfillment and deal with exceptions. As a virtual enterprise, Amazon's operations, using thousands of trading partners, requires a very different approach to fulfillment than the traditional 'take an order and ship it from your own warehouse' model. Amazon had no choice but to develop a complex, expensive and custom solution to tackle this problem as there used to be no product solution available. Now, other companies who want to follow similar models have a better off-the-shelf choice -- Oracle Distributed Order Orchestration (DOO).  Consider how another of our customers is using our distributed orchestration solution. This major airplane manufacturer has a highly complex business and interacts regularly with the U.S. Government and major airlines. It sits in the middle of an intricate supply chain and needed to improve visibility across its many different entities. Oracle Fusion DOO gives the company an orchestration mechanism so it could improve quality, speed, flexibility, and consistency without requiring an organ transplant of these highly complex legacy systems. Many retailers face the challenge of dealing with brick and mortar, Web, and reseller channels. They all need to be knitted together into a virtual enterprise experience that is consistent for their customers. When a large U.K. grocer with a strong brick and mortar retail operation added an online business, they turned to Oracle Fusion DOO to bring these entities together. Disturbing the Peace with Acquisitions Quite often a company's ERP system is disrupted when it acquires a new company. An acquisition can inject a new set of processes and systems -- or even introduce an entirely new business like Sun's hardware did at Oracle. This challenge has been a driver for some of our DOO customers. A large power management company is using Oracle Fusion DOO to provide the flexibility to rapidly integrate additional products and services into its central fulfillment operation. The Flip Side of Fulfillment Meanwhile, we haven't ignored similar challenges on the supply side of the equation. Specifically, how to manage complex supply in a flexible way when there are multiple trading parties involved? How to manage the supply to suppliers? How to manage critical components that need to merge in a tier two or tier three supply chain? By investing in supply orchestration solutions for the virtual enterprise, we plan to give users better visibility into their network of suppliers to help them drive down costs. We also think this technology and full orchestration process can be applied to the financial side of organizations. An example is transactions that flow through complex internal structures to minimize tax exposure. We can help companies manage those transactions effectively by thinking about the internal organization as a virtual enterprise and bringing the same solution set to this internal challenge.  The Clear Front Runner No other company is investing in solving the virtual enterprise supply chain issues like Oracle is. Oracle is in a unique position to become the gold standard in this market space. We have the infrastructure of Oracle technology. We already have an Oracle Fusion DOO application which embraces the best of what's required in this area. And we're absolutely committed to extending our Fusion solution to other use cases and delivering even more business value.

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• Achieving more fluent movement

  - by Robin92

  I'm working on my first OpenGL 2D game and I've just locked the framerate of my game. However, the way objects move is far from satisfying: they tend to lag, which is shown in this video. I've thought how more fluent animation can be achieved and started getting segmentation faults due to accessing the same object by two different threads. I've tried the following threads' setting: Drawing, creating new objects Moving player, moving objects, deleting objects Currently my application uses this setting: Drawing, creating new objects, moving objects, deleting object Moving player Any ideas would be appreciated. EDIT: I've tried increasing the FPS limit but lags are noticeable even at 200 fps.

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• Physics System ignores collision in some rare cases

  - by Gajoo

  I've been developing a simple physics engine for my game. since the game physics is very simple I've decided to increase accuracy a little bit. Instead of formal integration methods like fourier or RK4, I'm directly computing the results after delta time "dt". based on the very first laws of physics : dx = 0.5 * a * dt^2 + v0 * dt dv = a * dt where a is acceleration and v0 is object's previous velocity. Also to handle collisions I've used a method which is somehow different from those I've seen so far. I'm detecting all the collision in the given time frame, stepping the world forward to the nearest collision, resolving it and again check for possible collisions. As I said the world consist of very simple objects, so I'm not loosing any performance due to multiple collision checking. First I'm checking if the ball collides with any walls around it (which is working perfectly) and then I'm checking if it collides with the edges of the walls (yellow points in the picture). the algorithm seems to work without any problem except some rare cases, in which the collision with points are ignored. I've tested everything and all the variables seem to be what they should but after leaving the system work for a minute or two the system the ball passes through one of those points. Here is collision portion of my code, hopefully one of you guys can give me a hint where to look for a potential bug! void PhysicalWorld::checkForPointCollision(Vec2 acceleration, PhysicsComponent& ball, Vec2& collisionNormal, float& collisionTime, Vec2 target) { // this function checks if there will be any collision between a circle and a point // ball contains informations about the circle (it's current velocity, position and radius) // collisionNormal is an output variable // collisionTime is also an output varialbe // target is the point I want to check for collisions Vec2 V = ball.mVelocity; Vec2 A = acceleration; Vec2 P = ball.mPosition - target; float wallWidth = mMap->getWallWidth() / (mMap->getWallWidth() + mMap->getHallWidth()) / 2; float r = ball.mRadius / (mMap->getWallWidth() + mMap->getHallWidth()); // r is ball radius scaled to match actual rendered object. if (A.any()) // todo : I need to first correctly solve the collisions in case there is no acceleration return; if (V.any()) // if object is not moving there will be no collisions! { float D = P.x * V.y - P.y * V.x; float Delta = r*r*V.length2() - D*D; if(Delta < eps) return; Delta = sqrt(Delta); float sgnvy = V.y > 0 ? 1: (V.y < 0?-1:0); Vec2 c1(( D*V.y+sgnvy*V.x*Delta) / V.length2(), (-D*V.x+fabs(V.y)*Delta) / V.length2()); Vec2 c2(( D*V.y-sgnvy*V.x*Delta) / V.length2(), (-D*V.x-fabs(V.y)*Delta) / V.length2()); float t1 = (c1.x - P.x) / V.x; float t2 = (c2.x - P.x) / V.x; if(t1 > eps && t1 <= collisionTime) { collisionTime = t1; collisionNormal = c1; } if(t2 > eps && t2 <= collisionTime) { collisionTime = t2; collisionNormal = c2; } } } // this function should step the world forward by dt. it doesn't check for collision of any two balls (components) // it just checks if there is a collision between the current component and 4 points forming a rectangle around it. void PhysicalWorld::step(float dt) { for (unsigned i=0;i<mObjects.size();i++) { PhysicsComponent &current = *mObjects[i]; Vec2 acceleration = current.mForces * current.mInvMass; float rt=dt; // stores how much more the world should advance while(rt > eps) { float collisionTime = rt; Vec2 collisionNormal = Vec2(0,0); float halfWallWidth = mMap->getWallWidth() / (mMap->getWallWidth() + mMap->getHallWidth()) / 2; // we check if there is any collision with any of those 4 points around the ball // if there is a collision both collisionNormal and collisionTime variables will change // after these functions collisionTime will be exactly the value of nearest collision (if any) // and if there was, collisionNormal will report in which direction the ball should return. checkForPointCollision(acceleration,current,collisionNormal,collisionTime,Vec2(floor(current.mPosition.x) + halfWallWidth,floor(current.mPosition.y) + halfWallWidth)); checkForPointCollision(acceleration,current,collisionNormal,collisionTime,Vec2(floor(current.mPosition.x) + halfWallWidth, ceil(current.mPosition.y) - halfWallWidth)); checkForPointCollision(acceleration,current,collisionNormal,collisionTime,Vec2( ceil(current.mPosition.x) - halfWallWidth,floor(current.mPosition.y) + halfWallWidth)); checkForPointCollision(acceleration,current,collisionNormal,collisionTime,Vec2( ceil(current.mPosition.x) - halfWallWidth, ceil(current.mPosition.y) - halfWallWidth)); // either if there is a collision or if there is not we step the forward since we are sure there will be no collision before collisionTime current.mPosition += collisionTime * (collisionTime * acceleration * 0.5 + current.mVelocity); current.mVelocity += collisionTime * acceleration; // if the ball collided with anything collisionNormal should be at least none zero in one of it's axis if (collisionNormal.any()) { collisionNormal *= Dot(collisionNormal, current.mVelocity) / collisionNormal.length2(); current.mVelocity -= 2 * collisionNormal; // simply reverse velocity along collision normal direction } rt -= collisionTime; } // reset all forces for current object so it'll be ready for later game event current.mForces.zero(); } }

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• How do I communicate with an IronPython component in a C#/XNA game?

  - by Jonathan Hobbs

  My XNA game is component-oriented, and has various components for position, physics representation, rendering, etc, all of which extend a base Component class. The player and enemies also have controllers which are currently defined in C#. I'd like to turn them into Python scripts, but I'm not sure how to interact with those scripts. The examples in Embedding IronPython in a C# Application suggest I'd have to create a wrapper class (e.g. a Script component) which compiles a Python script, and call the Update methods of the component in the script Is this the most effective way of working with a Python object? I feel that I'm missing something in my research - there must be a way to load up a script, instantiate a Python object and then work directly with it from within C#. Or is the wrapper required?

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• Oracle Sequences

  - by jkrebsbach

  Reminder to myself - SQL Server has nice index columns directly tied to their tables. Oracle has sequences that are islands to themselves. select seq_name.currval from dual; select seq_name.nextval from dual; currval - return current number at top of sequence nextval - increment sequence by 1, return new number   therefore - to create functionality in oracle similar to an index column - OPTION A) - Create insert trigger: CREATE OR REPLACE TRIGGER dept_bir BEFORE INSERT ON departments FOR EACH ROW WHEN (new.id IS NULL) BEGIN SELECT dept_seq.NEXTVAL INTO :new.id FROM dual; END; This will handle creating a unique identity, but will not necessarily inform process flow of identity without additional logic. OPTION B) - Select indentity into temp variable, insert whole item into tab **** When attemptint to query currval, the below error was being thrown - SELECT seq_name.currval from dual; ERROR : TABLE OR VIEW DOES NOT EXIST *** Although Oracle sys tables may have access to the sequences, that isn't to say the Oracle user may have access to those sequences - verify permissions when the system can't see object that are being reported in the object explorer.

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• The practical cost of swapping effects

  - by sebf

  I use XNA for my projects and on those forums I sometimes see references to the fact that swapping an effect for a mesh has a relatively high cost, which surprises me as I thought to swap an effect was simply a case of copying the replacement shader program to the GPU along with appropriate parameters. I wondered if someone could explain exactly what is costly about this process? And put, if possible, 'relatively' into context? For example say I wanted to use a short shader to help with picking, I would: Change the effect on every object, calculting a unique color to identify it and providing it to the shader. Draw all the objects to a render target in memory. Get the color from the target and use it to look up the selected object. What portion of the total time taken to complete that process would be spent swapping the shaders? My instincts would say that rendering the scene again, no matter how simple the shader, would be an order of magnitude slower than any other part of the process so why all the concern over effects?

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• Endeca Information Discovery 3-Day Hands-on Training Workshop

  - by Mike.Hallett(at)Oracle-BI&EPM

  For Oracle Partners, on October 3-5, 2012 in Milan, Italy: Register here. Endeca Information Discovery plays a key role with your big data analysis and complements Oracle Business Intelligence Solutions such as OBIEE. This FREE hands-on workshop for Oracle Partners highlights technical know-how of the product and helps understand its value proposition. We will walk you through four key components of the product: Oracle Endeca Server—A highly scalable, search-analytical database that derives the data model based on the data presented to it, thereby reducing data modeling requirements. Studio—A highly interactive, component-based user interface for configuring advanced, yet intuitive, analytical applications. Integration Suite—Provides rapid unification and enrichment of diverse sources of information into a single integrated view. Extensible Value-Added Modules—Add-on modules that provide value quickly through configuration instead of custom coding. Topics covered will include Data Exploration with Endeca Information Discovery, Data Ingest, Project Lifecycle, Building an Endeca Server data model and advanced modeling techniques, and Working with Studio. Lab Outline The labs showcase Oracle Endeca Information Discovery components and functionality by providing expertise on features and know-how of building such applications. The hands-on activities are based on a Quick Start application provided during the class. Audience Oracle Partners, Big Data Analytics Developer and Architects BI and EPM Application Developers and Implementers, Data Warehouse Developers Equipment Requirements This workshop requires attendees to provide their own laptops for this class. Attendee laptops must meet the following minimum hardware/software requirements: Hardware 8GB RAM is highly recommended (Windows 64 bit Machine is required) 40 GB free space (includes staging) USB 2.0 port (at least one available) Software One of the following operating systems: 64-bit Windows host/laptop OS (Windows 7 or Windows Server 2008) 64-bit host/laptop OS with a Windows VM (Server, or Win 7, BIC2g, etc.) Internet Explorer 8.x , Firefox 3.6 or Firefox 6.0 WINRAR or 7ziputility to unzip workshop files: Download-able from http://www.win-rar.com/download.html Download-able from http://www.7zip.com/ Oracle Endeca Information Discovery Workshop Register here: October 3-5, 2012: Cinisello Balsamo, Milan.  We will confirm with you your place within 2 weeks. Questions?  Send email to: [email protected]  :  Oracle Platform Technologies Enablement Services.

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• Code Behaviour via Unit Tests

  - by Dewald Galjaard

  Normal 0 false false false EN-ZA X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Some four months ago my car started acting up. Symptoms included a sputtering as my car’s computer switched between gears intermittently. Imagine building up speed, then when you reach 80km/h the car magically and mysteriously decide to switch back to third or even second gear. Clearly it was confused! I managed to track down a technician, an expert in his field to help me out. As he fitted his handheld computer to some hidden port under the dash, he started to explain “These cars are quite intelligent, you know. When they sense something is wrong they run in a restrictive program which probably account for how you managed to drive here in the first place...”  I was surprised and thought this was certainly going to be an interesting test drive. The car ran smoothly down the first couple of stretches as the technician ran through routine checks. Then he said “Ok, all looking good. We need to start testing aspects of the gearbox. Inside the gearbox there are a couple of sensors. One of them is a speed sensor which talks to the computer, which in turn will decide which gear to switch to. The restrictive program avoid these sensors altogether and allow the computer to obtain its input from other [non-affected] sources”. Then, as soon as he forced the speed sensor to come back online the symptoms and ill behaviour re-emerged... What an incredible analogy for getting into a discussion on unit testing software? Besides I should probably put my ill fortune to some good use, right? This example provide a lot of insight into how and why we should conduct unit tests when writing code. More importantly, it captures what is easily and unfortunately often the most overlooked goal of writing unit tests by those new to the art and those who oppose it alike - The goal of writing unit tests is to test the behaviour of our code under predefined conditions. Although it is very possible to test the intrinsic workings of each and every component in your code, writing several tests for each method in practise will soon prove to be an exhausting and ultimately fruitless exercise given the certain and ever changing nature of business requirements. Consequently it is true and quite possible whilst conducting proper unit tests, to call any single method several times as you examine and contemplate different scenarios. Let’s write some code to demonstrate what I mean. In my example I make use of the Moq framework and NUnit to create my tests. Truly you can use whatever you’re comfortable with. First we’ll create an ISpeedSensor interface. This is to represent the speed sensor located in the gearbox.  Then we’ll create a Gearbox class which we’ll pass to a constructor when we instantiate an object of type Computer. All three are described below.   ISpeedSensor.cs namespace AutomaticVehicle {     public interface ISpeedSensor     {         int ReportCurrentSpeed();     } }   Gearbox.cs namespace AutomaticVehicle {      public class Gearbox     {         private ISpeedSensor _speedSensor;           public Gearbox( ISpeedSensor gearboxSpeedSensor )         {             _speedSensor = gearboxSpeedSensor;         }         /// <summary>         /// This method obtain it's reading from the speed sensor.         /// </summary>         /// <returns></returns>         public int ReportCurrentSpeed()         {             return _speedSensor.ReportCurrentSpeed();         }     } } Computer.cs namespace AutomaticVehicle {     public class Computer     {         private Gearbox _gearbox;         public Computer( Gearbox gearbox )         {                     }          public int GetCurrentSpeed()         {             return _gearbox.ReportCurrentSpeed( );         }     } } Since this post is about Unit testing, that is exactly what we’ll create next. Create a second project in your solution. I called mine AutomaticVehicleTests and I immediately referenced the respective nunit, moq and AutomaticVehicle dll’s. We’re going to write a test to examine what happens inside the Computer class. ComputerTests.cs namespace AutomaticVehicleTests {     [TestFixture]     public class ComputerTests     {         [Test]         public void Computer_Gearbox_SpeedSensor_DoesThrow()         {             // Mock ISpeedSensor in gearbox             Mock< ISpeedSensor > speedSensor = new Mock< ISpeedSensor >( );             speedSensor.Setup( n => n.ReportCurrentSpeed() ).Throws<Exception>();             Gearbox gearbox = new Gearbox( speedSensor.Object );               // Create Computer instance to test it's behaviour  towards an exception in gearbox             Computer carComputer = new Computer( gearbox );             // For simplicity let’s assume for now the car only travels at 60 km/h.             Assert.AreEqual( 60, carComputer.GetCurrentSpeed( ) );          }     } }   What is happening in this test? We have created a mocked object using the ISpeedsensor interface which we've passed to our Gearbox object. Notice that I created the mocked object using an interface, not the implementation. I’ll talk more about this in future posts but in short I do this to accentuate the fact that I'm not not really concerned with how SpeedSensor work internally at this particular point in time. Next I’ve gone ahead and created a scenario where I’ve declared the speed sensor in Gearbox to be faulty by forcing it to throw an exception should we ask Gearbox to report on its current speed. Sneaky, sneaky. This test is a simulation of how things may behave in the real world. Inevitability things break, whether it’s caused by mechanical failure, some logical error on your part or a fellow developer which didn’t consult the documentation (or the lack thereof ) - whether you’re calling a speed sensor, making a call to a database, calling a web service or just trying to write a file to disk. It’s a scenario I’ve created and this test is about how the code within the Computer instance will behave towards any such error as I’ve depicted. Now, if you’ve followed closely in my final assert method you would have noticed I did something quite unexpected. I might be getting ahead of myself now but I’m testing to see if the value returned is equal to what I expect it to be under perfect conditions – I’m not testing to see if an error has been thrown! Why is that? Well, in short this is TDD. Test Driven Development is about first writing your test to define the result we want, then to go back and change the implementation within your class to obtain the desired output (I need to make sure I can drive back to the repair shop. Remember? ) So let’s go ahead and run our test as is. It’s fails miserably... Good! Let’s go back to our Computer class and make a small change to the GetCurrentSpeed method.   Computer.cs public int GetCurrentSpeed() {   try   {     return _gearbox.ReportCurrentSpeed( );   }   catch   {     RunRestrictiveProgram( );   } }     This is a simple solution, I know, but it does provide a way to allow for different behaviour. You’re more than welcome to provide an implementation for RunRestrictiveProgram should you feel the need to. It's not within the scope of this post or related to the point I'm trying to make. What is important is to notice how the focus has shifted in our approach from how things can break - to how things behave when broken.   Happy coding!

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• Create named criteria in EJB Data control

  - by shantala.sankeshwar

  This article gives the detailed steps on creating named criteria in EJB Data control.Note that this feature is available in Jdev version 11.1.2.0.0Use Case DescriptionSuppose we have defined an EJB Entity Object & we would like to filter the Entity object based on some criteria,then this filtering can be achieved by creating named criteria in EJB Data Control.Implementation stepsLet us suppose that we have created Java EE Web Application with Entities from Emp table Create session bean,generate data control for the same Edit empFindAll in DataControls.dcx fileCreate simple Named Criteria: deptno>=20Create on '+' icon to create Named Criteria:Refresh the Data Controls & create a new jspx page.Drop EmpCriteria as ADF Query Panel with TableRun the page,click on search button & we will see that Emp table shows filtered records

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• Understanding how texCUBE works and writing cubemaps properly into a cube rendertarget

  - by cubrman

  My goal is to create accurate reflections, sampled from a dynamic cubemap, for specific 3d objects (mostly lights) in XNA 4.0. To sample the cubemap I compute the 3d reflection vector in a classic way: half3 ReflectionVec = reflect(-directionToCamera, Normal.rgb); I then use the vector to get the actual reflected color: half3 ReflectionCol = texCUBElod(ReflectionSampler, float4(ReflectionVec, 0)); The cubemap I am sampling from is a RenderTarget with 6 flat faces. So my question is, given the 3d world position of an arbitrary 3d object, how can I make sure that I get accurate reflections of this object, when I re-render the cubemap. Should I build the ViewProjection matrix in a specific way? Or is there any other approach?

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• Virtualized data centre&ndash;Part four: The design

  - by marc dekeyser

  Welcome back to the fourth post in this series! Today we will have a look at what Microsoft recommends as a “private cloud design” and what I will make of it. Whilst my own solution is based of the reference architecture, it is quite different indeed! An important thing to know is that, whilst I am using the private cloud as a reference, I am skipping most of the steps in designing a private cloud. If that is why you are here, please read the links at the end of the article and skim through my own content. A private cloud is much more process driven than just building a virtual infrastructure… The architecture of it all… So imagine for a minute that you have unlimited funds to build this lab of yours… You’d want redundancy on all levels and separation of each network where possible! Unfortunately we don’t have that luxury and, as you saw me hinting at in the previous article, our own design will be more limited but still quite capable! Networking From the networking perspective I will not have a fully redundant network, after all, this is but a lab environment! Thanks to Server 2012 I will be able to use bonding on my NIC’s and use LACP to improve the performance on that part. Storage As I mentioned in the previous article a Synology DS1218+ will be used for iSCSI provisioning. This device has 2 NICs on-board which can be bonded in to one 2 Gbps interface giving me a decent throughput and making the disks the most limiting factor in the storage design. Domain controllers and extra infrastructure Server 2012 completely supports running domain controllers virtualized and has no need to actually have a reachable DC when booting… That being said I need a remote access machine to power on the hosts (I have no need for them running 24/7) and a possible System Center VMM 2012 box (although server 2012 is not supported until SP1 :( ). Undecided on if I am to install those boxes separately or as a virtual machine… Which amounts to… Something like this pretty picture!                   Sources Microsoft Private Cloud Solutions Repository (en-US) http://social.technet.microsoft.com/wiki/contents/articles/12131.microsoft-private-cloud-solutions-repository-en-us.aspx Reference  Architecture: http://social.technet.microsoft.com/wiki/contents/articles/3819.reference-architecture-for-private-cloud.aspx Private Cloud Reference Model: http://social.technet.microsoft.com/wiki/contents/articles/4399.private-cloud-reference-model.aspx

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• Learn about the Performance and Tuning Improvements made to Oracle's E-Business Suite

  Cliff speaks with Ahmed Alomari, Sr. Director, Oracle Applications Performance about key performance improvements that have been made to Oracle's E-Business Suite 11.5.10, the top 3 tuning tips to improve Workflow performance, why customers should adopt Oracle Applications Tablespace Model, Java monitoring, and J2SE 5 performance improvements.

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• Gnome 3 after run has graphic problems

  - by Antonis

  I have 3d accelarator but gnome still doesn't work My pc enters gnome desktop bu there i have graphic problems! Graphic problems with the top taskbar and wherever i click it, my desktop transforms into gnome clasic desktop. I am using ati radeon 4800 hd and ubuntu 11.10 Not software rendered: yes Not blacklisted: yes GLX fbconfig: yes GLX texture from pixmap: yes GL npot or rect textures: yes GL vertex program: yes GL fragment program: yes GL vertex buffer object: yes GL framebuffer object: yes GL version is 1.4+: yes Unity 3D supported: yes Similar report from @user26930 - ATI HD5770 graphics card - gnome-shell is affected but Unity works fine.

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• How to use OO for data analysis? [closed]

  - by Konsta

  In which ways could object-orientation (OO) make my data analysis more efficient and let me reuse more of my code? The data analysis can be broken up into get data (from db or csv or similar) transform data (filter, group/pivot, ...) display/plot (graph timeseries, create tables, etc.) I mostly use Python and its Pandas and Matplotlib packages for this besides some DB connectivity (SQL). Almost all of my code is a functional/procedural mix. While I have started to create a data object for a certain collection of time series, I wonder if there are OO design patterns/approaches for other parts of the process that might increase efficiency?

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• Software Center doesn't open (elementary luna - ubuntu 12.04)

  - by zbiba

  When i try to open software center on elementary luna i get the bellow error.... ERROR:root:DebFileApplication import Traceback (most recent call last): File "/usr/share/software-center/softwarecenter/db/init.py", line 4, in from debfile import DebFileApplication, DebFileOpenError File "/usr/share/software-center/softwarecenter/db/debfile.py", line 25, in from softwarecenter.db.application import Application, AppDetails File "/usr/share/software-center/softwarecenter/db/application.py", line 27, in import softwarecenter.distro File "/usr/share/software-center/softwarecenter/distro/init.py", line 198, in distro_instance = _get_distro() File "/usr/share/software-center/softwarecenter/distro/init.py", line 175, in _get_distro distro_class = getattr(module, distro_id) AttributeError: 'module' object has no attribute 'debian' Traceback (most recent call last): File "/usr/sbin/update-software-center", line 38, in from softwarecenter.db.update import rebuild_database File "/usr/share/software-center/softwarecenter/db/update.py", line 33, in from softwarecenter.distro import get_distro File "/usr/share/software-center/softwarecenter/distro/init.py", line 198, in distro_instance = _get_distro() File "/usr/share/software-center/softwarecenter/distro/init.py", line 175, in _get_distro distro_class = getattr(module, distro_id) AttributeError: 'module' object has no attribute 'debian'

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• DX9 Deferred Rendering, GBuffer displays as clear color only

  - by Fire31

  I'm trying to implement Catalin Zima's Deferred Renderer in a very lightweight c++ DirectX 9 app (only renders a skydome and a model), at this moment I'm trying to render the gbuffer, but I'm having a problem, the screen shows only the clear color, no matter how much I move the camera around. However, removing all the render target operations lets the app render the scene normally, even if the models are being applied the renderGBuffer effect. Any ideas of what I'm doing wrong?

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• django & postgres linux hosting (with SSH access) recommendations

  - by Justin Grant

  We're looking for a good place to host our custom Django app (a fork of OSQA) and its postgresql backend. Requirements include: Linux Python 2.6 or (ideally) Python 2.7 Django 1.2 Postgres 8.4 or later DB backup/restore handled by the hoster, not us OS & dev-platform-stack patching/maintenance handled by the hoster, not us SSH access (so we can pull source code from GitHub, so we can install python eggs, etc.) ability to set up cron jobs (e.g. to send out dail email updates) ability to send up to 10K emails/day good performance (not ganged up with a zillion other sites on one CPU, not starved for RAM) FTP or SCP access to web logs dedicated public IP SSL support Costs under $1000/month for a relatively small site (<5M pageviews/month) Good customer service We already have a prototype site running on EC2 on top of a Bitnami DjangoStack. The problem is that we have to patch the OS, patch postgres, etc. We'd really prefer a platform-as-a-service (PaaS) offering, like Heroku offers for Rails apps, where all we need to worry about is deploying our code instead of worrying about system software patching and maintenance. Google App Engine is closest to what we're looking for, but they don't offer relational DB access (not yet at least). Anyone have a recommendation?

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