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  • Libgdx 2D Game, Random generated World of random size, how to get mouse coordinates?

    - by Solom
    I'm a noob and English is not my mothertongue, so please bear with me! I'm generating a map for a Sidescroller out of a 2D-array. That is, the array holds different values and I create blocks based on that value. Now, my problem is to match mouse coordinates on screen with the actual block the mouse is pointing at. public class GameScreen implements Screen { private static final int WIDTH = 100; private static final int HEIGHT = 70; private OrthographicCamera camera; private Rectangle glViewport; private Spritebatch spriteBatch; private Map map; private Block block; ... @Override public void show() { camera = new OrthographicCamera(WIDTH, HEIGHT); camera.position.set(WIDTH/2, HEIGHT/2, 0); glViewport = new Rectangle(0, 0, WIDTH, HEIGHT); map = new Map(16384, 256); map.printTileMap(); // Debugging only spriteBatch = new SpriteBatch(); } @Override public void render(float delta) { // Clear previous frame Gdx.gl.glClearColor(1, 1, 1, 1 ); Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT); GL30 gl = Gdx.graphics.getGL30(); // gl.glViewport((int) glViewport.x, (int) glViewport.y, (int) glViewport.width, (int) glViewport.height); spriteBatch.setProjectionMatrix(camera.combined); camera.update(); spriteBatch.begin(); // Draw Map this.drawMap(); // spriteBatch.flush(); spriteBatch.end(); } private void drawMap() { for(int a = 0; a < map.getHeight(); a++) { // Bounds check (y) if(camera.position.y + camera.viewportHeight < a)// || camera.position.y - camera.viewportHeight > a) break; for(int b = 0; b < map.getWidth(); b++) { // Bounds check (x) if(camera.position.x + camera.viewportWidth < b)// || camera.position.x > b) break; // Dynamic rendering via BlockManager int id = map.getTileMap()[a][b]; Block block = BlockManager.map.get(id); if(block != null) // Check if Air { block.setPosition(b, a); spriteBatch.draw(block.getTexture(), b, a, 1 ,1); } } } } As you can see, I don't use the viewport anywhere. Not sure if I need it somewhere down the road. So, the map is 16384 blocks wide. One block is 16 pixels in size. One of my naive approaches was this: if(Gdx.input.isButtonPressed(Input.Buttons.LEFT)) { Vector3 mousePos = new Vector3(); mousePos.set(Gdx.input.getX(), Gdx.input.getY(), 0); camera.unproject(mousePos); System.out.println(Math.round(mousePos.x)); // *16); // Debugging // TODO: round // map.getTileMap()[mousePos.x][mousePos.y] = 2; // Draw at mouse position } I confused myself somewhere down the road I fear. What I want to do is, update the "block" (or rather the information in the Map/2D-Array) so that in the next render() there is another block. Basically drawing on the spriteBatch g So if anyone could point me in the right direction this would be highly appreciated. Thanks!

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  • Is this method of writing Unit Tests correct?

    - by aspdotnetuser
    I have created a small C# project to help me learn how to write good unit tests. I know that one important rule of unit testing is to test the smallest 'unit' of code possible so that if it fails you know exactly what part of the code needs to fixed. I need help with the following before I continue to implement more unit tests for the project: If I have a Car class, for example, that creates a new Car object which has various attributes that are calculated when its' constructor method is called, would the two following tests be considered as overkill? Should there be one test that tests all calculated attributes of the Car object instead? [Test] public void CarEngineCalculatedValue() { BusinessObjects.Car car= new BusinessObjects.Car(); Assert.GreaterOrEqual(car.Engine, 1); } [Test] public void CarNameCalculatedValue() { BusinessObjects.Car car= new BusinessObjects.Car(); Assert.IsNotNull(car.Name); } Should I have the above two test methods to test these things or should I have one test method that asserts the Car object has first been created and then test these things in the same test method?

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  • Missing Fields and Default Values

    - by PointsToShare
    © 2011 By: Dov Trietsch. All rights reserved Dealing with Missing Fields and Default Values New fields and new default values are not propagated throughout the list. They only apply to new and updated items and not to items already entered. They are only prospective. We need to be able to deal with this issue. Here is a scenario. The user has an old list with old items and adds a new field. The field is not created for any of the old items. Trying to get its value raises an Argument Exception. Here is another: a default value is added to a field. All the old items, where the field was not assigned a value, do not get the new default value. The two can also happen in tandem – a new field is added with a default. The older items have neither. Even better, if the user changes the default value, the old items still carry the old defaults. Let’s go a bit further. You have already written code for the list, be it an event receiver, a feature receiver, a console app or a command extension, in which you span all the fields and run on selected items – some new (no problem) and some old (problems aplenty). Had you written defensive code, you would be able to handle the situation, including similar changes in the future. So, without further ado, here’s how. Instead of just getting the value of a field in an item – item[field].ToString() – use the function below. I use ItemValue(item, fieldname, “mud in your eye”) and if “mud in your eye” is what I get, I know that the item did not have the field.   /// <summary> /// Return the column value or a default value /// </summary> private static string ItemValue(SPItem item, string column, string defaultValue) {     try     {         return item[column].ToString();     }     catch (NullReferenceException ex)     {         return defaultValue;     }     catch (ArgumentException ex)     {         return defaultValue;     } } I also use a similar function to return the default and a funny default-default to ascertain that the default does not exist. Here it is:  /// <summary> /// return a fields default or the "default" default. /// </summary> public static string GetFieldDefault(SPField fld, string defValue) {     try     {         // -- Check if default exists.         return fld.DefaultValue.ToString();     }     catch (NullReferenceException ex)     {         return defValue;     }     catch (ArgumentException ex)     {         return defValue;     } } How is this defensive? You have trapped an expected error and dealt with it. Therefore the program did not stop cold in its track and the required code ran to its end. Now, take a further step - write to a log (See Logging – a log blog). Read your own log every now and then, and act accordingly. That’s all Folks!

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  • Lucene best practice

    - by Dragos
    I am trying to understand how Lucene should be used. From what I have read, creating an IndexReader is costly, so using a Search Manager shoulg be the right choice. However, a SearchManager should be produced by a NRTManager(which, by the way, should replace the IndexWriter for every add or delete operation performed). But in order to have a NRTManager, I should first have an IndexWriter, and here comes my problem. The documentation says: an IndexWriter is thread-safe the constructor of this class takes a Directory object, so it seems creating an instace should be costly(as in the case of an IndexReader) all changes are buffered and flushed periodically(so they seem to encourage using a single instance) but: the changes, although flushed will only be visible after commit or close after finished making updates(add/delete), the instance should be closed I also found this: http://stackoverflow.com/questions/5374419/forgot-to-close-the-lucene-indexwriter-after-adding-documents-to-the-index where it is said that not closing a writer might ruin everything So what am I really supposed to do? Is having a single IndexWriter instance a good idea(make only commit and never close it)? EDIT: What is more, if I use NRTManager, how can I make acommit`? Is it even possible?

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  • Avoid overwriting all the methods in the child class

    - by Heckel
    The context I am making a game in C++ using SFML. I have a class that controls what is displayed on the screen (manager on the image below). It has a list of all the things to draw like images, text, etc. To be able to store them in one list I created a Drawable class from which all the other drawable class inherit. The image below represents how I would organize each class. Drawable has a virtual method Draw that will be called by the manager. Image and Text overwrite this method. My problem is that I would like Image::draw method to work for Circle, Polygon, etc. since sf::CircleShape and sf::ConvexShape inherit from sf::Shape. I thought of two ways to do that. My first idea would be for Image to have a pointer on sf::Shape, and the subclasses would make it point onto their sf::CircleShape or sf::ConvexShape classes (Like on the image below). In the Polygon constructor I would write something like ptr_shape = &polygon_shape; This doesn't look very elegant because I have two variables that are, in fact, just one. My second idea is to store the sf::CircleShape and sf::ConvexShape inside the ptr_shape like ptr_shape = new sf::ConvexShape(...); and to use a function that is only in ConvexShape I would cast it like so ((sf::ConvexShape*)ptr_shape)->convex_method(); But that doesn't look very elegant either. I am not even sure I am allowed to do that. My question I added details about the whole thing because I thought that maybe my whole architecture was wrong. I would like to know how I could design my program to be safe without overwriting all the Image methods. I apologize if this question has already been asked; I have no idea what to google.

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  • this.BoundingBox.Intersects(Wall[0].BoundingBox) not working properly

    - by Pieter
    I seem to be having this problem a lot, I'm still learning XNA / C# and well, trying to make a classic paddle and ball game. The problem I run into (and after debugging have no answer) is that everytime I run my game and press either of the movement keys, the Paddle won't move. Debugging shows that it never gets to the movement part, but I can't understand why not? Here's my code: // This is the If statement for checking Left movement. if (keyboardState.IsKeyDown(Keys.Left) || keyboardState.IsKeyDown(Keys.A)) { if (!CheckCollision(walls[0])) { Location.X -= Velocity; } } //This is the CheckCollision(Wall wall) boolean public bool CheckCollision(Wall wall) { if (this.BoundingBox.Intersects(wall.BoundingBox)) { return true; } return false; } As far as I can tell there should be absolutely no problem with this, I initialize the bounding box in the constructor whenever a new instance of Walls and Paddle is created. this.BoundingBox = new Rectangle(0, 0, Sprite.Width, Sprite.Height); Any idea as to why this isn't working? I have previously succeeded with using the whole Location.X < Wall.Location.X + Wall.Texture.Width code... But to me that seems like too much coding if a simple boolean check could be done.

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  • Service layer coupling

    - by Justin
    I am working on writing a service layer for an order system in php. It's the typical scenario, you have an Order that can have multiple Line Items. So lets say a request is received to store a line item with pictures and comments. I might receive a json request such as { 'type': 'Bike', 'color': 'Red', 'commentIds': [3193,3194] 'attachmentIds': [123,413] } My idea was to have a Service_LineItem_Bike class that knows how to take the json data and store an entity for a bike. My question is, the Service_LineItem class now needs to fetch comments and file attachments, and store the relationships. Service_LineItem seems like it should interact with a Service_Comment and a Service_FileUpload. Should instances of these two other services be instantiated and passed to the Service_LineItem constructor,or set by getters and setters? Dependency injection seems like the right solution, allowing a service access to a 'service fetching helper' seems wrong, and this should stay at the application level. I am using Doctrine 2 as a ORM, and I can technically write a dql query inside Service_LineItem to fetch the comments and file uploads necessary for the association, but this seems like it would have a tighter coupling, rather then leaving this up to the right service object.

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  • PHP-FPM stops responding and dies [migrated]

    - by user12361
    I'm running Drupal 6 with Nginx 1.5.1 and PHP-FPM (PHP 5.3.26) on a 1GB single core VPS with 3GB of swap space on SSD storage. I just switched from shared hosting to this unmanaged VPS because my site was getting too heavy, so I'm still learning the ropes. I have moderately high traffic, I don't really monitor it closely but Google Adsense usually record close to 30K page views/day. I usually have 50 to 80 authenticated users logged in and a few hundred more anonymous users hitting the Boost static HTML cache at any given moment. The problem I'm having is that PHP-FPM frequently stops responding, resulting in Nginx 502 or 504 errors. I swear I have read every page on the internet about this issue, which seems fairly common, and I've tried endless combinations of configurations, and I can't find a good solution. After restarting Nginx and PHP-FPM, the site runs really fast for a while, and then without warning it simply stops responding. I get a white screen while the browser waits on the server, and after about 30 seconds to a minute it throws an Nginx 502 or 504 error. Sometimes it runs well for 2 minutes, sometimes 5 minutes, sometimes 5 hours, but it always ends up hanging. When I find the server in this state, there is still plenty of free memory (500MB or more) and no major CPU usage, the control and worker PHP-FPM processes are still present, and the server is still pingable and usable via SSH. A reload of PHP-FPM via the init script revives it again. The hangups don't seem to correspond to the amount of traffic, because I observed this behavior consistently when I was testing this configuration on a development VPS with no traffic at all. I've been constantly tweaking the settings, but I can't definitively eliminate the problem. I set Nginx workers to just 1. In the PHP-FPM config I have tried all three of the process managers. "Dynamic" is definitely the least reliable, consistently hanging up after only a few minutes. "Static" also has been unreliable and unpredictable. The least buggy has been "ondemand", but even that is failing me, sometimes after as much as 12 to 24 hours. But I can't leave the server unattended because PHP-FPM dies and never comes back on its own. I tried adjusting the pm.max_children value from as low as 3 to as high as 50, doesn't make a lot of difference, but I currently have it at 10. Same thing for the spare servers values. I also have set pm.max_requests anywhere from 30 to unlimited, and it doesn't seem to make a difference. According to the logs, the PHP-FPM processes are not exiting with SIGSEGV or SIGBUS, but rather with SIGTERM. I get a lot of lines like: WARNING: [pool www] child 3739, script '/var/www/drupal6/index.php' (request: "GET /index.php") execution timed out (38.739494 sec), terminating and: WARNING: [pool www] child 3738 exited on signal 15 (SIGTERM) after 50.004380 seconds from start I actually found several articles that recommend doing a graceful reload of PHP-FPM via cron every few minutes or hours to circumvent this issue. So that's what I did, "/etc/init.d/php-fpm reload" every 5 minutes. So far, it's keeping the lights on. But it feels like a dreadful hack. Is PHP-FPM really that unreliable? Is there anything else I can do? Thanks a lot!

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  • jBullet Collision/Physics not working as expected

    - by Kenneth Bray
    Below is the code for one of my objects in the game I am creating (yes although this is a cube, I am not making anything remotely like MineCraft), and my issue is I while the cube will display and is does follow the physics if the cube falls, it does not interact with any other objects in the game. If I was to have multiple cubes in screen at once they all just sit there, or shoot off in all directions never stopping. Anyway, I am new to jBullet, and any help would be appreciated. // Constructor public Cube(float pX, float pY, float pZ, float pSize) { posX = pX; posY = pY; posZ = pZ; size = pSize; rotX = 0; rotY = 0; rotZ = 0; // physics stuff fallMotionState = new DefaultMotionState(new Transform(new Matrix4f(new Quat4f(0, 0, 0, 1), new Vector3f(posX, posY, posZ), 1))); fallRigidBodyCI = new RigidBodyConstructionInfo(mass, fallMotionState, fallShape, fallInertia); fallRigidBody = new RigidBody(fallRigidBodyCI); }

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  • XNA 4.0 - Purple/Pink Tint Over All Sprites After Viewing in FullScreen

    - by D. Dubya
    I'm a noob to the game dev world and recently finished the 2D XNA tutorial from http://www.pluralsight.com. Everything was perfect until I decided to try the game in Fullscreen mode. The following code was added to the Game1 constructor. graphics.PreferredBackBufferWidth = 800; graphics.PreferredBackBufferHeight = 480; graphics.IsFullScreen = true; As soon as it launched in Fullscreen, I noticed that the entire game was tinted. None of the colours were appearing as they should. That code was removed, the game then launched in the 800x480 window, however the tint remained. I commented out all my Draw code so that all that was left was GraphicsDevice.Clear(Color.CornflowerBlue); //spriteBatch.Begin(); //gameState.Draw(spriteBatch, false); //spriteBatch.End(); //spriteBatch.Begin(SpriteSortMode.Deferred, BlendState.Additive); //gameState.Draw(spriteBatch, true); //spriteBatch.End(); base.Draw(gameTime); The result was an empty window that was tinted Purple, not Blue. I changed the GraphicsDevice.Clear colour to Color.White and the window was tinted Pink. Color.Transparent gave a Black window. Even tried rebooting my PC but the 'tint' still remains. I'm at a loss here.

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  • The Growing Importance of Network Virtualization

    - by user12608550
    The Growing Importance of Network Virtualization We often focus on server virtualization when we discuss cloud computing, but just as often we neglect to consider some of the critical implications of that technology. The ability to create virtual environments (or VEs [1]) means that we can create, destroy, activate and deactivate, and more importantly, MOVE them around within the cloud infrastructure. This elasticity and mobility has profound implications for how network services are defined, managed, and used to provide cloud services. It's not just servers that benefit from virtualization, it's the network as well. Network virtualization is becoming a hot topic, and not just for discussion but for companies like Oracle and others who have recently acquired net virtualization companies [2,3]. But even before this topic became so prominent, Solaris engineers were working on technologies in Solaris 11 to virtualize network services, known as Project Crossbow [4]. And why is network virtualization so important? Because old assumptions about network devices, topology, and management must be re-examined in light of the self-service, elasticity, and resource sharing requirements of cloud computing infrastructures. Static, hierarchical network designs, and inter-system traffic flows, need to be reconsidered and quite likely re-architected to take advantage of new features like virtual NICs and switches, bandwidth control, load balancing, and traffic isolation. For example, traditional multi-tier Web services (Web server, App server, DB server) that share net traffic over Ethernet wires can now be virtualized and hosted on shared-resource systems that communicate within a larger server at system bus speeds, increasing performance and reducing wired network traffic. And virtualized traffic flows can be monitored and adjusted as needed to optimize network performance for dynamically changing cloud workloads. Additionally, as VEs come and go and move around in the cloud, static network configuration methods cannot easily accommodate the routing and addressing flexibility that VE mobility implies; virtualizing the network itself is a requirement. Oracle Solaris 11 [5] includes key network virtualization technologies needed to implement cloud computing infrastructures. It includes features for the creation and management of virtual NICs and switches, and for the allocation and control of the traffic flows among VEs [6]. Additionally it allows for both sharing and dedication of hardware components to network tasks, such as allocating specific CPUs and vNICs to VEs, and even protocol-specific management of traffic. So, have a look at your current network topology and management practices in view of evolving cloud computing technologies. And don't simply duplicate the physical architecture of servers and connections in a virtualized environment…rethink the traffic flows among VEs and how they can be optimized using Oracle Solaris 11 and other Oracle products and services. [1] I use the term "virtual environment" or VE here instead of the more commonly used "virtual machine" or VM, because not all virtualized operating system environments are full OS kernels under the control of a hypervisor…in other words, not all VEs are VMs. In particular, VEs include Oracle Solaris zones, as well as SPARC VMs (previously called LDoms), and x86-based Solaris and Linux VMs running under hypervisors such as OEL, Xen, KVM, or VMware. [2] Oracle follows VMware into network virtualization space with Xsigo purchase; http://www.mercurynews.com/business/ci_21191001/oracle-follows-vmware-into-network-virtualization-space-xsigo [3] Oracle Buys Xsigo; http://www.oracle.com/us/corporate/press/1721421 [4] Oracle Solaris 11 Networking Virtualization Technology, http://www.oracle.com/technetwork/server-storage/solaris11/technologies/networkvirtualization-312278.html [5] Oracle Solaris 11; http://www.oracle.com/us/products/servers-storage/solaris/solaris11/overview/index.html [6] For example, the Solaris 11 'dladm' command can be used to limit the bandwidth of a virtual NIC, as follows: dladm create-vnic -l net0 -p maxbw=100M vnic0

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  • Looking for a better Factory pattern (Java)

    - by Sam Goldberg
    After doing a rough sketch of a high level object model, I am doing iterative TDD, and letting the other objects emerge as a refactoring of the code (as it increases in complexity). (That whole approach may be a discussion/argument for another day.) In any case, I am at the point where I am looking to refactor code blocks currently in an if-else blocks into separate objects. This is because there is another another value combination which creates new set of logical sub-branches. To be more specific, this is a trading system feature, where buy orders have different behavior than sell orders. Responses to the orders have a numeric indicator field which describes some event that occurred (e.g. fill, cancel). The combination of this numeric indicator field plus whether it is a buy or sell, require different processing buy the code. Creating a family of objects to separate the code for the unique handling each of the combinations of the 2 fields seems like a good choice at this point. The way I would normally do this, is to create some Factory object which when called with the 2 relevant parameters (indicator, buysell), would return the correct subclass of the object. Some times I do this pattern with a map, which allows to look up a live instance (or constructor to use via reflection), and sometimes I just hard code the cases in the Factory class. So - for some reason this feels like not good design (e.g. one object which knows all the subclasses of an interface or parent object), and a bit clumsy. Is there a better pattern for solving this kind of problem? And if this factory method approach makes sense, can anyone suggest a nicer design?

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  • An observation on .NET loops – foreach, for, while, do-while

    It’s very common that .NET programmers use “foreach” loop for iterating through collections. Following is my observation whilst I was testing simple scenario on loops. “for” loop is 30% faster than “foreach” and “while” loop is 50% faster than “foreach”. “do-while” is bit faster than “while”. Someone may feel that how does it make difference if I’m iterating only 1000 times in a loop. This test case is only for simple iteration. According to the "Data structure" concepts, best and worst cases are completely based on the data we provide to the algorithm. so we can not conclude that a "foreach" algorithm is not good. All I want to tell that we need to be little cautious even choosing the loops. Example:- You might want to chose quick sort when you want to sort more numbers. At the same time bubble sort may be effective than quick sort when you want to sort less numbers. Take a simple scenario, a request of a simple web application fetches the data of 10000 (10K) rows and iterating them for some business logic. Think, this application is being accessed by 1000 (1K) people simultaneously. In this simple scenario you are ending up with 10000000 (10Million or 1 Crore) iterations. below is the test scenario with simple console application to test 100 Million records. using System;using System.Collections.Generic;using System.Diagnostics;namespace ConsoleApplication1{ class Program { static void Main(string[] args) { var sw = new Stopwatch(); var numbers = GetSomeNumbers(); sw.Start(); foreach (var item in numbers) { } sw.Stop(); Console.WriteLine( String.Format("\"foreach\" took {0} milliseconds", sw.ElapsedMilliseconds)); sw.Reset(); sw.Start(); for (int i = 0; i < numbers.Count; i++) { } sw.Stop(); Console.WriteLine( String.Format("\"for\" loop took {0} milliseconds", sw.ElapsedMilliseconds)); sw.Reset(); sw.Start(); var it = 0; while (it++ < numbers.Count) { } sw.Stop(); Console.WriteLine( String.Format("\"while\" loop took {0} milliseconds", sw.ElapsedMilliseconds)); sw.Reset(); sw.Start(); var it2 = 0; do { } while (it2++ < numbers.Count); sw.Stop(); Console.WriteLine( String.Format("\"do-while\" loop took {0} milliseconds", sw.ElapsedMilliseconds)); } #region Get me 10Crore (100 Million) numbers private static List<int> GetSomeNumbers() { var lstNumbers = new List<int>(); var count = 100000000; for (var i = 1; i <= count; i++) { lstNumbers.Add(i); } return lstNumbers; } #endregion Get me some numbers }} In above example, I was just iterating through 100 Million numbers. You can see the time to execute various  loops provided in .NET Output "foreach" took 1108 milliseconds "for" loop took 727 milliseconds "while" loop took 596 milliseconds "do-while" loop took 594 milliseconds   Press any key to continue . . . So I feel we need to be careful while choosing the looping strategy. Please comment your thoughts. span.fullpost {display:none;}

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  • Hopping/Tumbling Windows Could Introduce Latency.

    This is a pre-article to one I am going to be writing on adjusting an event’s time and duration to satisfy business process requirements but it is one that I think is really useful when understanding the way that Hopping/Tumbling windows work within StreamInsight.  A Tumbling window is just a special shortcut version of  a Hopping window where the width of the window is equal to the size of the hop Here is the simplest and often used definition for a Hopping Window.  You can find them all here public static CepWindowStream<CepWindow<TPayload>> HoppingWindow<TPayload>(     this CepStream<TPayload> source,     TimeSpan windowSize,     TimeSpan hopSize,     WindowInputPolicy inputPolicy,     HoppingWindowOutputPolicy outputPolicy )   And here is the definition for a Tumbling Window public static CepWindowStream<CepWindow<TPayload>> TumblingWindow<TPayload>(     this CepStream<TPayload> source,     TimeSpan windowSize,     WindowInputPolicy inputPolicy,     HoppingWindowOutputPolicy outputPolicy )   These methods allow you to group events into windows of a temporal size.  It is a really useful and simple feature in StreamInsight.  One of the downsides though is that the windows cannot be flushed until an event in a following window occurs.  This means that you will potentially never see some events or see them with a delay.  Let me explain. Remember that a stream is a potentially unbounded sequence of events. Events in StreamInsight are given a StartTime.  It is this StartTime that is used to calculate into which temporal window an event falls.  It is best practice to assign a timestamp from the source system and not one from the system clock on the processing server.  StreamInsight cannot know when a window is over.  It cannot tell whether you have received all events in the window or whether some events have been delayed which means that StreamInsight cannot flush the stream for you.   Imagine you have events with the following Timestamps 12:10:10 PM 12:10:20 PM 12:10:35 PM 12:10:45 PM 11:59:59 PM And imagine that you have defined a 1 minute Tumbling Window over this stream using the following syntax var HoppingStream = from shift in inputStream.TumblingWindow(TimeSpan.FromMinutes(1),HoppingWindowOutputPolicy.ClipToWindowEnd) select new WindowCountPayload { CountInWindow = (Int32)shift.Count() };   The events between 12:10:10 PM and 12:10:45 PM will not be seen until the event at 11:59:59 PM arrives.  This could be a real problem if you need to react to windows promptly This can always be worked around by using a different design pattern but a lot of the examples I see assume there is a constant, very frequent stream of events resulting in windows always being flushed. Further examples of using windowing in StreamInsight can be found here

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  • Should I expose IObservable<T> on my interfaces?

    - by Alex
    My colleague and I have dispute. We are writing a .NET application that processes massive amounts of data. It receives data elements, groups subsets of them into blocks according to some criterion and processes those blocks. Let's say we have data items of type Foo arriving some source (from the network, for example) one by one. We wish to gather subsets of related objects of type Foo, construct an object of type Bar from each such subset and process objects of type Bar. One of us suggested the following design. Its main theme is exposing IObservable objects directly from the interfaces of our components. // ********* Interfaces ********** interface IFooSource { // this is the event-stream of objects of type Foo IObservable<Foo> FooArrivals { get; } } interface IBarSource { // this is the event-stream of objects of type Bar IObservable<Bar> BarArrivals { get; } } / ********* Implementations ********* class FooSource : IFooSource { // Here we put logic that receives Foo objects from the network and publishes them to the FooArrivals event stream. } class FooSubsetsToBarConverter : IBarSource { IFooSource fooSource; IObservable<Bar> BarArrivals { get { // Do some fancy Rx operators on fooSource.FooArrivals, like Buffer, Window, Join and others and return IObservable<Bar> } } } // this class will subscribe to the bar source and do processing class BarsProcessor { BarsProcessor(IBarSource barSource); void Subscribe(); } // ******************* Main ************************ class Program { public static void Main(string[] args) { var fooSource = FooSourceFactory.Create(); var barsProcessor = BarsProcessorFactory.Create(fooSource) // this will create FooSubsetToBarConverter and BarsProcessor barsProcessor.Subscribe(); fooSource.Run(); // this enters a loop of listening for Foo objects from the network and notifying about their arrival. } } The other suggested another design that its main theme is using our own publisher/subscriber interfaces and using Rx inside the implementations only when needed. //********** interfaces ********* interface IPublisher<T> { void Subscribe(ISubscriber<T> subscriber); } interface ISubscriber<T> { Action<T> Callback { get; } } //********** implementations ********* class FooSource : IPublisher<Foo> { public void Subscribe(ISubscriber<Foo> subscriber) { /* ... */ } // here we put logic that receives Foo objects from some source (the network?) publishes them to the registered subscribers } class FooSubsetsToBarConverter : ISubscriber<Foo>, IPublisher<Bar> { void Callback(Foo foo) { // here we put logic that aggregates Foo objects and publishes Bars when we have received a subset of Foos that match our criteria // maybe we use Rx here internally. } public void Subscribe(ISubscriber<Bar> subscriber) { /* ... */ } } class BarsProcessor : ISubscriber<Bar> { void Callback(Bar bar) { // here we put code that processes Bar objects } } //********** program ********* class Program { public static void Main(string[] args) { var fooSource = fooSourceFactory.Create(); var barsProcessor = barsProcessorFactory.Create(fooSource) // this will create BarsProcessor and perform all the necessary subscriptions fooSource.Run(); // this enters a loop of listening for Foo objects from the network and notifying about their arrival. } } Which one do you think is better? Exposing IObservable and making our components create new event streams from Rx operators, or defining our own publisher/subscriber interfaces and using Rx internally if needed? Here are some things to consider about the designs: In the first design the consumer of our interfaces has the whole power of Rx at his/her fingertips and can perform any Rx operators. One of us claims this is an advantage and the other claims that this is a drawback. The second design allows us to use any publisher/subscriber architecture under the hood. The first design ties us to Rx. If we wish to use the power of Rx, it requires more work in the second design because we need to translate the custom publisher/subscriber implementation to Rx and back. It requires writing glue code for every class that wishes to do some event processing.

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  • Is wrapping a third party code the only solution to unit test its consumers? [closed]

    - by Songo
    I'm doing unit testing and in one of my classes I need to send a mail from one of the methods, so using constructor injection I inject an instance of Zend_Mail class which is in Zend framework. Now some people argue that if a library is stable enough and won't change often then there is no need to wrap it. So assuming that Zend_Mail is stable and won't change and it fits my needs entirely, then I won't need a wrapper for it. Now take a look at my class Logger that depends on Zend_Mail: class Logger{ private $mailer; function __construct(Zend_Mail $mail){ $this->mail=$mail; } function toBeTestedFunction(){ //Some code $this->mail->setTo('some value'); $this->mail->setSubject('some value'); $this->mail->setBody('some value'); $this->mail->send(); //Some } } However, Unit testing demands that I test one component at a time, so I need to mock the Zend_Mail class. In addition I'm violating the Dependency Inversion principle as my Logger class now depends on concretion not abstraction. Now is wrapping Zend_Mail the only solution or is there a better approach to this problem? The code is in PHP, but answers doesn't have to be. This is more of a design issue than a language specific feature

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  • Is having a single `IndexWriter` instance in Lucene a good idea?

    - by Dragos
    I am trying to understand how Lucene should be used. From what I have read, creating an IndexReader is costly, so using a Search Manager shoulg be the right choice. However, a SearchManager should be produced by a NRTManager(which, by the way, should replace the IndexWriter for every add or delete operation performed). But in order to have a NRTManager, I should first have an IndexWriter, and here comes my problem. The documentation says: an IndexWriter is thread-safe the constructor of this class takes a Directory object, so it seems creating an instace should be costly(as in the case of an IndexReader) all changes are buffered and flushed periodically(so they seem to encourage using a single instance) but: the changes, although flushed will only be visible after commit or close after finished making updates(add/delete), the instance should be closed I also found this: http://stackoverflow.com/questions/5374419/forgot-to-close-the-lucene-indexwriter-after-adding-documents-to-the-index where it is said that not closing a writer might ruin everything So what am I really supposed to do? Is having a single IndexWriter instance a good idea (make only commit and never close it)? EDIT: What is more, if I use NRTManager, how can I make acommit`? Is it even possible?

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  • What is causing this behavior with the movement of Pong Ball in 2D? [closed]

    - by thegermanpole
    //edit after running it through the debugger it turned out i had the display function set to x,x...TIL how to use a debugger I've been trying to teach myself C++ SDL with the lazyfoo tutorial and seem to have run into a roadblock. The code below is the movement function of my Dot class, which controls the ball. The ball seems to ignore yvel and moves with xvel to the bottom right. The code should be pretty readable, the rest of the relevant facts are: All variables are names Constants are in caps dotrad is the radius of my dot yvel and xvel are set to 5 in the constructor The dot is created at x and y equal to 100 When I comment out the x movement block it doesn't move, but if i comment out the y movement block, it keeps on going down to the right. void Dot::move() { if(((y+yvel+dotrad) <= SCREEN_HEIGHT) && (0 <= (y-dotrad+yvel))) { y+=yvel; } else { yvel = -1*yvel; } if(((x+xvel+dotrad) <= SCREEN_WIDTH) && (0 <= (x-dotrad+xvel))) { x +=xvel; } else { xvel = -1*xvel; } }

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  • Instead of the specified Texture, black circles on a green background are getting rendered. Why?

    - by vinzBad
    I'm trying to render a Texture via OpenGL. But instead of the texture black circles on a green background are rendered. (They scale, depending what the rotation of the texture is) Example: The texture I'm trying to render is the following: This is the code I use to render the texture, it's located in my Sprite-class. public void Render() { Matrix4 matrix = Matrix4.CreateTranslation(-OriginX, -OriginY, 0) * Matrix4.CreateRotationZ(Rotation) * Matrix4.CreateTranslation(X, Y, 0); Vector2[] corners = { new Vector2(0,0), //top left new Vector2(Width ,0),//top right new Vector2(Width,Height),//bottom rigth new Vector2(0,Height)//bottom left }; //copy the corners to the uv coordinates Vector2[] uv = corners.ToArray<Vector2>(); //transform the coordinates for (int i = 0; i < 4; i++) corners[i] = new Vector2(Vector3.Transform(new Vector3(corners[i]), matrix)); //GL.Color3(TintColor); GL.BindTexture(TextureTarget.Texture2D, _ID); GL.Begin(BeginMode.Quads); { for (int i = 0; i < 4; i++) { GL.TexCoord2(uv[i]); GL.Vertex3(corners[i].X, corners[i].Y, _layerDepth); } } GL.End(); if (EnableDebugDraw) { GL.Color3(Color.Violet); GL.PointSize(3); GL.Begin(BeginMode.Points); { for (int i = 0; i < 4; i++) GL.Vertex2(corners[i]); } GL.End(); GL.Color3(Color.Green); GL.Begin(BeginMode.Points); GL.Vertex2(X, Y); GL.End(); } } This is how I setup OpenGL. public static void SetupGL() { GL.Enable(EnableCap.AlphaTest); GL.AlphaFunc(AlphaFunction.Greater, 0.1f); GL.Enable(EnableCap.Texture2D); GL.Hint(HintTarget.PerspectiveCorrectionHint, HintMode.Nicest); } With this function I load the texture: public static uint LoadTexture(string path) { uint id; GL.GenTextures(1, out id); GL.BindTexture(TextureTarget.Texture2D, id); Bitmap bitmap = new Bitmap(path); BitmapData data = bitmap.LockBits(new System.Drawing.Rectangle(0, 0, bitmap.Width, bitmap.Height), ImageLockMode.ReadOnly, System.Drawing.Imaging.PixelFormat.Format32bppArgb); GL.TexImage2D(TextureTarget.Texture2D, 0, PixelInternalFormat.Rgba, data.Width, data.Height, 0, OpenTK.Graphics.OpenGL.PixelFormat.Bgra, PixelType.UnsignedByte, data.Scan0); bitmap.UnlockBits(data); GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMinFilter, (int)TextureMinFilter.Linear); GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMagFilter, (int)TextureMagFilter.Linear); return id; } And here I call Sprite.Render() protected override void OnRenderFrame(FrameEventArgs e) { GL.ClearColor(Color.MidnightBlue); GL.Clear(ClearBufferMask.ColorBufferBit); _sprite.Render(); SwapBuffers(); base.OnRenderFrame(e); } As I stole this code from the Textures-Example from OpenTK, I don't understand why this doesn't work.

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  • why my code still cannot connect with database? [closed]

    - by Wen Teng
    package com.mems.travis; import java.util.ArrayList; import java.util.List; import org.apache.http.NameValuePair; import org.apache.http.message.BasicNameValuePair; import org.json.JSONObject; import android.app.Activity; import android.app.AlertDialog; import android.content.DialogInterface; import android.content.Intent; import android.os.AsyncTask; import android.os.Bundle; import android.util.Log; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.widget.RadioButton; public class UserRegister extends Activity { JSONParser jsonParser = new JSONParser(); EditText inputName; EditText inputUsername; EditText inputEmail; EditText inputPassword; RadioButton button1; RadioButton button2; Button button3; int success = 0; // url to create new product private static String url_register_user = "http://192.168.1.100/MEMS/add_user.php"; // JSON Node names private static final String TAG_SUCCESS = "success"; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_user_register); // Edit Text inputName = (EditText) findViewById(R.id.nameTextBox); inputUsername = (EditText) findViewById(R.id.usernameTextBox); inputEmail = (EditText) findViewById(R.id.emailTextBox); inputPassword = (EditText) findViewById(R.id.pwTextBox); // Create button //RadioButton button1 = (RadioButton) findViewById(R.id.studButton); // RadioButton button2 = (RadioButton) findViewById(R.id.shopownerButton); Button button3 = (Button) findViewById(R.id.regSubmitButton); // button click event button3.setOnClickListener(new View.OnClickListener() { public void onClick(View view) { String name = inputName.getText().toString(); String username = inputUsername.getText().toString(); String email = inputEmail.getText().toString(); String password = inputPassword.getText().toString(); if (name.contentEquals("")||username.contentEquals("")||email.contentEquals("")||password.contentEquals("")) { AlertDialog.Builder builder = new AlertDialog.Builder(UserRegister.this); // 2. Chain together various setter methods to set the dialog characteristics builder.setMessage(R.string.nullAlert) .setTitle(R.string.alertTitle); builder.setPositiveButton(R.string.ok, new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int id) { // User clicked OK button } }); // 3. Get the AlertDialog from create() AlertDialog dialog = builder.show(); } else { new RegisterNewUser().execute(); } } }); } class RegisterNewUser extends AsyncTask<String, String, String>{ protected String doInBackground(String... args) { String name = inputName.getText().toString(); String username = inputUsername.getText().toString(); String email = inputEmail.getText().toString(); String password = inputPassword.getText().toString(); // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("name", name)); params.add(new BasicNameValuePair("username", username)); params.add(new BasicNameValuePair("email", email)); params.add(new BasicNameValuePair("password", password)); // getting JSON Object // Note that create product url accepts POST method JSONObject json = jsonParser.makeHttpRequest(url_register_user, "GET", params); // check log cat for response Log.d("Send Notification", json.toString()); try { int success = json.getInt(TAG_SUCCESS); if (success == 1) { // successfully created product Intent i = new Intent(getApplicationContext(), StudentLogin.class); startActivity(i); finish(); } else { // failed to register } } catch (Exception e) { e.printStackTrace(); } return null; } } }

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  • Are Vala and desktopcouch ready?

    - by pavolzetor
    Hi, I have started writting rss reader in Vala, but I don't know, what database system should I use, I cannot connect to couchdb and sqlite works fine, but I would like use couchdb because of ubuntu one. I have natty with latest updates public CouchDB.Session session; public CouchDB.Database db; public string feed_table = "feed"; public string item_table = "item"; public struct field { string name; string val; } // constructor public Database() { try { this.session = new CouchDB.Session(); } catch (Error e) { stderr.printf ("%s a\n", e.message); } try { this.db = new CouchDB.Database (this.session, "test"); } catch (Error e) { stderr.printf ("%s a\n", e.message); } try { this.session.get_database_info("test"); } catch (Error e) { stderr.printf ("%s aa\n", e.message); } try { var newdoc = new CouchDB.Document (); newdoc.set_boolean_field ("awesome", true); newdoc.set_string_field ("phone", "555-VALA"); newdoc.set_double_field ("pi", 3.14159); newdoc.set_int_field ("meaning_of_life", 42); this.db.put_document (newdoc); // store document } catch (Error e) { stderr.printf ("%s aaa\n", e.message); } reports $ ./xml_parser rss.xmlCannot connect to destination (127.0.0.1) aa Cannot connect to destination (127.0.0.1) aaa

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  • Where we should put validation for domain model

    - by adisembiring
    I still looking best practice for domain model validation. Is that good to put the validation in constructor of domain model ? my domain model validation example as follows: public class Order { private readonly List<OrderLine> _lineItems; public virtual Customer Customer { get; private set; } public virtual DateTime OrderDate { get; private set; } public virtual decimal OrderTotal { get; private set; } public Order (Customer customer) { if (customer == null) throw new ArgumentException("Customer name must be defined"); Customer = customer; OrderDate = DateTime.Now; _lineItems = new List<LineItem>(); } public void AddOderLine //.... public IEnumerable<OrderLine> AddOderLine { get {return _lineItems;} } } public class OrderLine { public virtual Order Order { get; set; } public virtual Product Product { get; set; } public virtual int Quantity { get; set; } public virtual decimal UnitPrice { get; set; } public OrderLine(Order order, int quantity, Product product) { if (order == null) throw new ArgumentException("Order name must be defined"); if (quantity <= 0) throw new ArgumentException("Quantity must be greater than zero"); if (product == null) throw new ArgumentException("Product name must be defined"); Order = order; Quantity = quantity; Product = product; } } Thanks for all of your suggestion.

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  • Encapsulate standard C functions?

    - by Jack Stout
    While studying the C programming language and learning safe practices, I'm inclined to write a layer of functionality over several parts of the standard library. This would serve two purposes: I could use standard parts of the language in ways that feel more familiar or rational to me, and I could easily replace that functionality with my own, if I needed to. I could benefit from this, but should I do it? As an example, we can consider memory management. If I've written malloc() into the constructors of each of my objects, then decide that I need to handle memory allocation on my own, I have to edit the constructor associated with every object. By referencing my own function, I can change the contents of that function without writing a new constructors. It seems obvious that I should do this, but I'm used to Python. I'm extremely comfortable in that environment and have no problem linking to any part of the standard library from any part of my program because I know I will almost certainly leave that relationship untouched for the life of the project. The situation I'm running into with C feels like I'm trying to hide the language from myself. Will writing a layer of functionality over the C standard library help me in learning the language and developing a codebase, or will it stifle my understanding going forward?

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  • Rendering multiple squares fast?

    - by Sam
    so I'm doing my first steps with openGL development on android and I'm kinda stuck at some serious performance issues... What I'm trying to do is render a whole grid of single colored squares on to the screen and I'm getting framerates of ~7FPS. The squares are 9px in size right now with one pixel border in between, so I get a few thousand of them. I have a class "Square" and the Renderer iterates over all Squares every frame and calls the draw() method of each (just the iteration is fast enough, with no openGL code the whole thing runs smootlhy at 60FPS). Right now the draw() method looks like this: // Prepare the square coordinate data GLES20.glVertexAttribPointer(mPositionHandle, COORDS_PER_VERTEX, GLES20.GL_FLOAT, false, vertexStride, vertexBuffer); // Set color for drawing the square GLES20.glUniform4fv(mColorHandle, 1, color, 0); // Draw the square GLES20.glDrawElements(GLES20.GL_TRIANGLES, drawOrder.length, GLES20.GL_UNSIGNED_SHORT, drawListBuffer); So its actually only 3 openGL calls. Everything else (loading shaders, filling buffers, getting appropriate handles, etc.) is done in the Constructor and things like the Program and the handles are also static attributes. What am I missing here, why is it rendering so slow? I've also tried loading the buffer data into VBOs, but this is actually slower... Maybe I did something wrong though. Any help greatly appreciated! :)

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  • Class or Dictionary

    - by user2038134
    I want to create a immutable Scale class in C#. public sealed class Scale { string _Name; string _Description; SomeOrderedCollection _ScaleValueDefinitions; Unit _Unit // properties .... // methods ContainsValue(double value) .... // constructors // all parameters except scalevaluedefinitions are optional // for a Scale to be useful atleast 1 ScaleValueDefinition should exist public Scale(string name, string description, SomeOrderedCollection scaleValueDefinitions, unit) { /* initialize */} } so first a ScaleValueDefinition should be represented by to values: Value (double) Definition (string) these values are known before the Scale class is created and should be unique. so what is the best approach. create a immutable class ScaleValueDefinition with value and definition as properties and use it in a list. use a dictionary. use another way i didn't think of... and how to implement it. for option 1. i can use params ScaleValueDefinition[] ValueDefinitions in the constructor, but how to do it for the other options? and as last at what amount of value's (properties) should i choose one option over the other?

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