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  • Creating a steady rhythm for music-based game in XNA

    - by A-Type
    I'm looking to develop a game for Windows Phone to explore an idea I had which involves the user building notes into a sequencer while playing a puzzle game. The issue I'm running into is that, while my implementation is very close to being on-beat, there is the occasional pause between beats which makes the whole thing sound sloppy. I'm just not sure how to get around this inside XNA's infrastructure. Currently I'm running this code in the Update method of my GameBoard: public void Update(GameTime gameTime) { onBeat = IsOnBeat(gameTime); [...] if (onBeat) BeatUpdate(); } private bool IsOnBeat(GameTime gameTime) { beatTime += gameTime.ElapsedGameTime.TotalSeconds; if (Math.Abs(beatTime - beatLength) < 0.0166666) { beatTime -= beatLength; return true; } return false; } private void BeatUpdate() { cursor.BeatUpdate(); board.CursorPass((int)cursor.CursorPosition % Board.GRID_WIDTH); } Update checks to see if the time is on beat, and if it is, it calls the BeatUpdate method which moves the cursor over the board (sequencer). The cursor reports its X position to the board, which then plays any notes which are in that position on the sequencer. Notes are SoundEffectInstances, preloaded and ready to play. Oh, and TargetElapsedTime is set to 166666, or 60FPS target. Obviously totaling up the time and then subtracting isn't the most accurate way to go but I can't figure out a way to work within XNA's system in order to overcome this issue. This current system is just horribly unstable. Beats lag and fire too early and it's obvious. I thought about perhaps some sort of threaded solution but I'm not familiar enough with multithreading to figure out how that would work. Any ideas?

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  • Will Unity skills be interchangeable?

    - by Starkers
    I'm currently learning Unity and working my way through a video game maths primer text book. My goal is to create a racing game for WebGL (using Three.js and maybe Physic.js). I'm well aware that the Unity program shields you from a lot of what's going on and a lot of the grunt work attached to developing even a simple video game, but if I power through a bunch of Unity tutorials, will a lot of the skills I learn translate over to other frameworks/engines? I'm pretty proficient at level design with WebGL, and I'm a good 3D modeller. My weaknesses are definitely AI and Physics. While I am rapidly shoring up my math, and while Physics is undeniably interesting there's only so many hours in the day and there's a wealth of engines out there to take care of this sort of thing. AI does appeal to me a lot more, and is a lot more necessary. AI changes drastically from game to game, is tweaked heavily during development, and the physics is a lot more constant. Will leaning AI concepts in Unity allow me to transfer this knowledge pretty much anywhere? Or will I just be paddling up Unity creek with these skills?

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  • Will I be able to get programming interviews at good software companies with a non-CS degree?

    - by friend
    I'll be graduating in a year, but I'll have a degree in Economics. I'm pretty much done with my Economics coursework, and by the time next year comes around I will have devoted 1.5 years to learning CS. I will have almost finished the requirements to graduate with a degree in CS, but unfortunately my school requires a science series that would add another 6-9 months of study if I were to try and get the degree (not to mention a max unit cap). I have or will have taken: Objected Oriented Programming Discrete Math Data structures Calculus through multivariable (doubt this matters at all) Linear Algebra (same) Computer Organization Operating Systems Computational Statistics (many data mining projects in R) Parallel Programming Programming Languages Databases Algorithms Compilers Artificial Intelligence I've done well in the ones I've taken, and I hope to do well in the rest, but will that matter if I can't say to the HR people that I have a CS degree? I'd be happy to get an internship at first too, so should I just apply as if I'm an intern and not looking for fulltime, and then try and parlay that into something? Sidenote if you have time -- Is a computer networks or theory of computation class important? Would it be worth taking either of those in lieu of a class on my list? edit -- I know this isn't AskReddit or College Confidential; I know there will be some outrage at posting a question like this. I'm merely looking for insight into a situation that I've been struggling with, and I think this is the absolute best place to find an answer to this question. Thanks.

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  • Higher Performance With Spritesheets Than With Rotating Using C# and XNA 4.0?

    - by Manuel Maier
    I would like to know what the performance difference is between using multiple sprites in one file (sprite sheets) to draw a game-character being able to face in 4 directions and using one sprite per file but rotating that character to my needs. I am aware that the sprite sheet method restricts the character to only be able to look into predefined directions, whereas the rotation method would give the character the freedom of "looking everywhere". Here's an example of what I am doing: Single Sprite Method Assuming I have a 64x64 texture that points north. So I do the following if I wanted it to point east: spriteBatch.Draw( _sampleTexture, new Rectangle(200, 100, 64, 64), null, Color.White, (float)(Math.PI / 2), Vector2.Zero, SpriteEffects.None, 0); Multiple Sprite Method Now I got a sprite sheet (128x128) where the top-left 64x64 section contains a sprite pointing north, top-right 64x64 section points east, and so forth. And to make it point east, i do the following: spriteBatch.Draw( _sampleSpritesheet, new Rectangle(400, 100, 64, 64), new Rectangle(64, 0, 64, 64), Color.White); So which of these methods is using less CPU-time and what are the pro's and con's? Is .NET/XNA optimizing this in any way (e.g. it notices that the same call was done last frame and then just uses an already rendered/rotated image thats still in memory)?

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  • What would be the fastest way of storing or calculating legal move sets for chess pieces?

    - by ioSamurai
    For example if a move is attempted I could just loop through a list of legal moves and compare the x,y but I have to write logic to calculate those at least every time the piece is moved. Or, I can store in an array [,] and then check if x and y are not 0 then it is a legal move and then I save the data like this [0][1][0][0] etc etc for each row where 1 is a legal move, but I still have to populate it. I wonder what the fastest way to store and read a legal move on a piece object for calculation. I could use matrix math as well I suppose but I don't know. Basically I want to persist the rules for a given piece so I can assign a piece object a little template of all it's possible moves considering it is starting from it's current location, which should be just one table of data. But is it faster to loop or write LINQ queries or store arrays and matrices? public class Move { public int x; public int y; } public class ChessPiece : Move { private List<Move> possibleMoves { get; set; } public bool LegalMove(int x, int y){ foreach(var p in possibleMoves) { if(p.x == x && p.y == y) { return true; } } } } Anyone know?

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  • LibGDX onTouch() method kill on touch

    - by johnny-b
    How can I add this on my application. i want to use the onTouch() method from the implementation of the InputProcessor to kill the enemies on screen. how do i do that? do i have to do anything to the enemy class? please help Thank you M @Override public boolean touchDown(int screenX, int screenY, int pointer, int button) { return false; } here is my enemy class public class Bullet extends Sprite { private Vector2 velocity; private float lifetime; public Bullet(float x, float y) { velocity = new Vector2(0, 0); } public void update(float delta) { float targetX = GameWorld.getBall().getX(); float targetY = GameWorld.getBall().getY(); float dx = targetX - getX(); float dy = targetY - getY(); float distToTarget = (float) Math.sqrt(dx * dx + dy * dy); velocity.x += dx * delta; velocity.y += dy * delta; } } i am rendering all graphics in a GameRender class and a gameworld class if you need more info please let me know Thank you

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  • How do spambots work?

    - by rlb.usa
    I have a forum that's getting hit a lot by forum spambots, and of course the best way to defeat something is to know thy enemy. I'll worry about defeating those spambots later, but right now I'd like to know more about them. Reading around, I felt surprised about the lack of thorough information on the subject (or perhaps my ineptness to input the correct search terms for better google results). I'm interested in learning all about spambots. I've asked on other forums and gotten brush-off answers like "Spambots are always users registering on your site." How do forum spambots work? How do they find the 'new user registration' page? (I'm especially surprised because some forums don't have a dedicated URL for this eg, www.forum.com/register.html , but instead use query strings or even other methods invisible to the URL bar) How do they know what to enter into each 'new user registration' field? How do they determine what's a page they can spam / enter data into and what is not? Do they even 'view' this page at all? ..If not, then I'd assume they're communicating with the server directly - how is - this possible? How do they do it? Can forum spambots break CAPTCHAs? Can they solve logic questions (how?)? Math questions? Do they reverse-engineer client-side anti-bot validation scripts? Server-side scripts? What techniques are still valid to prevent them? Where do spambots come from? Is someone sitting behind the computer snickering as they watch their bot destroy site after site? Or are they snickering as they simply 'release' it onto the internet somehow? Are spambots 'run' by an infected computer somewhere? Do they replicate themselves? etc

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  • How do I retain previously drawn graphics?

    - by Cromanium
    I've created a simple program that draws lines from a fixed point to a random point each frame. I wanted to keep each line on the screen. However, it always seems to be cleared each time it draws on the spriteBatch even without GraphicsDevice.Clear(color) being called. What seems to be the problem? protected override void Draw(GameTime gameTime) { spriteBatch.Begin(); DrawLine(spriteBatch); spriteBatch.End(); base.Draw(gameTime); } private void DrawLine(SpriteBatch spriteBatch) { Random r = new Random(); Vector2 a = new Vector2(50, 100); Vector2 b = new Vector2(r.Next(0, 640), r.Next(0,480)); Texture2D filler= new Texture2D(GraphicsDevice, 1, 1, false, SurfaceFormat.Color); filler.SetData(new[] { Color.Black }); float length = Vector2.Distance(a, b); float angle = (float)Math.Atan2(b.Y - a.Y, b.X - a.X); spriteBatch.Draw(filler, a, null, Color.Black, angle, Vector2.Zero, new Vector2(length,10.0f), SpriteEffects.None, 0f); } What am I doing wrong?

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  • Are my negative internship experiences representative of the real world? [closed]

    - by attemptAtAnonymity
    I'm curious if my current experiences as an intern are representative of actual industry. As background, I'm through the better part of two computing majors and a math major at a major university; I've aced every class and adored all of them, so I'd like to think that I'm not terrible at programming. I got an internship with one of the major software companies, and half way through now I've been shocked at the extraordinarily low quality of code. Comments don't exist, it's all spaghetti code, and everything that could be wrong is even worse. I've done a ton of tutoring/TAing, so I'm very used to reading bad code, but the major industry products I've been seeing trump all of that. I work 10-12 hours a day and never feel like I'm getting anywhere, because it's endless hours of trying to figure out an undocumented API or determine the behavior of some other part of the (completely undocumented) product. I've left work hating the job every day so far, and I desperately want to know if this is what is in store for the rest of my life. Did I draw a short straw on internships (the absurdly large paychecks imply that it's not a low quality position), or is this what the real world is like?

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  • Finding which tiles are intersected by a line, without looping through all of them or skipping any

    - by JustSuds
    I've been staring at this problem for a few days now. I rigged up this graphic to help me visualise the issue: http://i.stack.imgur.com/HxyP9.png (from the graph, we know that the line intersects [1, 1], [1, 2], [2, 2], [2, 3], ending in [3,3]) I want to step along the line to each grid space and check to see if the material of the grid space is solid. I feel like I already know the math involved, but I haven't been able to string it together yet. I'm using this to test line of sight and eliminate nodes after a path is found via my pathfinding algorithms - my agents cant see through a solid block, therefore they cant move through one, therefore the node is not eliminated from the path because it is required to navigate a corner. So, I need an algorithm that will step along the line to each grid space that it intersects. Any ideas? I've taken a look at a lot of common algorithms, like Bresenham's, and one that steps at predefined intervals along the line (unfortunately, this method skips tiles if they're intersecting with a smaller wedge than the step size). I'm populating my whiteboard now with a mass of floor() and ceil() functions - but its getting overly complicated and I'm afraid it might cause a slowdown.

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  • I want to make "stuff" on the web, is a BsC. in Computers necessary/overkill? [on hold]

    - by notypist
    I'm 24 and have a lead role in a major news outlet in my country, with a good pay and public image in the horizon. I hold a job that was previously held by people with 15-20 years of experience and considered one of the top 5 news anchors in my country. My passion though, is computers. The web, to be precise. I was a problogger at a very young age. I hacked my way through CSS and some basic HTML and PHP. But I want to move forward - I want to CREATE not just STRUCTURE things. Giving up the present (and especially the seemingly promising future) in my current industry is hard, my friends raise their eyebrows... I'm considering a BsC. in computer Engineering - but my stats are short of getting into a good university for this discipline. Plus, I'm not the best with math - although I do exceptionally well in statistics and other numbers that are more applicable to real life. I tried learning PHP through online websites, but that just "doesn't cut it" for me. Nope. So what are my options here? if I don't want to build hardware or and deal with overly-complex algorithmic but would like, for example - to build a well functioning iPhone and iPad app, or a SaaS, a startup...do I have to go the BsC. route? I don't see any option to get an "official" education in strictly "web" concepts and languages.. Note: I'm well off financially, so I'm doing this more to be able to create stuff, rather than get a job in a corporations. Although if I land somewhere high, that might be an option. But my main concern is getting the tools.

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  • Trying to sort the coefficients of the polynomial (z-a)(z-b)(z-c)...(z-n) into a vector

    - by pajamas
    So I have a factored polynomial of the form (z-a)(z-b)(z-c)...(z-n) for n an even positive integer. Thus the coefficient of z^k for 0 <= k < n will be the sum of all distinct n-k element products taken from the set {a,b,...,n} multiplied by (-1)^k, I hope that makes sense, please ask if you need more clarification. I'm trying to put these coefficients into a row vector with the first column containing the constant coefficient (which would be abc...n) and the last column containing the coefficient for z^n (which would be 1). I imagine there is a way to brute force this with a ton of nested loops, but I'm hoping there is a more efficient way. This is being done in Matlab (which I'm not that familiar with) and I know Matlab has a ton of algorithms and functions, so maybe its got something I can use. Can anyone think of a way to do this? Example: (z-1)(z-2)(z-3) = z^3 - (1 + 2 + 3)z^2 + (1*2 + 1*3 + 2*3)z - 1*2*3 = z^3 - 6z^2 + 11z - 6. Note that this example is n=3 odd, but n=4 would have taken too long to do by hand. Edit: Let me know if you think this would be better posted at TCS or Math Stack Exchange.

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  • Creating dynamic plots

    - by geoff92
    I'm completely new to web programming but I do have a programming background. I'd like to create a site that allows users to visit, enter some specifications into a form, submit the form, and then receive a graph. I have a few questions about this, only because I'm pretty ignorant: Is there a good framework I should start in? I know a lot of java, I'm okay with python, and I learned Ruby in the past. I figure I might use ruby on rails only because I hear of it so often and I think I've also heard it's easy. If anyone has some other recommendation, please suggest. The user will be entering data into a form. I'm guessing the request they'll be making should be one of a GET request, right? Because I don't intend for any of the data they're entering to modify my server (in fact, I don't intend on having a database). The data the user inputs will be used to perform calculations involving lots of matrices. I've written this functionality in python. If I use ruby on rails, should it be instead written in Ruby? Somewhere I've heard that you can either place the load of the work on your server or on the client's computer. Since the code performs heavy math, which option is preferable? How do I alter the setup to either make the client do the work or my server? Should I be using a "cgi-bin"? In the code that I have now, I use matplotlib, a python library, and then "show" the plot in order to see the graph. I specify the x and y limits, but I am able to "drag" the graph in order to see more data within the plot window. Ultimately, I want a graph to be shown on my site with the drag functionality. Is this possible? What if the client drags the graph so far, more computations must be made? Thanks!

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  • Problem with understanding how to start

    - by Coolface
    Okay, this might be a little off-topic but i try anyway. Sorry to bother. So i'm working as sysadmin for at least 5 years now and i quite enjoy IT field in general. Somehow i was never interested in programming much but always want to learn something at least easy and for personal usage. As sysadmin i need scripting skills so learn shell scripting without much problems, i also try to learn pascal, delphi, basic over time and must recent was python. Well, my problem is when i try to learn programming i just can't apply what i learn from the books to the real word. What i mean is i understand there are data structures, algorithms, variables, lib's, if-then logic, etc. but i just can't understand how to apply this things when i want to do real things. Like i want to get a something simple as parse web page, i draw a quick algorithm like get a web page, find a word on it and write a to file, on the paper everything look simple but when i get to the coding i just stuck pretty much from the start. I try read code of the real programs that just totally confusing especially big parts with many classes so i'm just quickly lost a trail what this code do. I think i just lack some fundamentals to see a big picture but don't really know what this might be? Or maybe i just don't have a passion to programming at all... My best bet was a shell scripting so i have really no problems to write complex scripts but this just not enough. Recently i was read around 5 or 6 python books because everyone say it's so easy even kid can code something but still no much luck, python is good and easy but i can't make something harder then a prodecurial style code like in bash for easy things but when i want harder things i'm still stuck. In college i was also not a math and tech guy and like to study non-tech stuff mostly like economy, psychology maybe that my problem? Anyway any advice would be greatly appriciated.

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  • Are my negative internship experiences respresentative of the real world?

    - by attemptAtAnonymity
    I'm curious if my current experiences as an intern are representative of actual industry. As background, I'm through the better part of two computing majors and a math major at a major university; I've aced every class and adored all of them, so I'd like to think that I'm not terrible at programming. I got an internship with one of the major software companies, and half way through now I've been shocked at the extraordinarily low quality of code. Comments don't exist, it's all spaghetti code, and everything that could be wrong is even worse. I've done a ton of tutoring/TAing, so I'm very used to reading bad code, but the major industry products I've been seeing trump all of that. I work 10-12 hours a day and never feel like I'm getting anywhere, because it's endless hours of trying to figure out an undocumented API or determine the behavior of some other part of the (completely undocumented) product. I've left work hating the job every day so far, and I desperately want to know if this is what is in store for the rest of my life. Did I draw a short straw on internships (the absurdly large paychecks imply that it's not a low quality position), or is this what the real world is like?

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  • Do I have to change my company to make sure I'm good enough? [closed]

    - by superM
    I have been working as a developer since my fourth year of university until now. I'm getting my master's degree next year (in math modeling). I've worked for the same company all the time, first on .Net, then on Android, and now .Net again. It seems I'm doing quite well in my current company. Some of my coursemates have tried to work in my company, but they failed after some time. This (and not only this) makes me think that I'm really worth something. But we're working on a very specific project. I was wondering if I am good enough and if I can make it in another company. I love my current job, but sometimes I have a feeling that I'm not moving on. So, is it possible to keep improving when working at the same company with the same technology and at similar tasks? I know that most of the programmers go from one place to another very frequently. Is it the only way?

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  • Function not returning value at all - not a void [migrated]

    - by user105439
    I have this function that is not returning a function value. I've added some random testers to try and debug but no luck. Thanks! #include <stdio.h> #include <math.h> #include <time.h> #define N 100 float error(int a, int b); int main(){ printf("START\n"); srand(time(NULL)); int a, b, j, m; float plot[N+1]; printf("Lower bound for x: "); scanf("%d", &a); printf("Upper bound for x: "); scanf("%d", &b); printf("okay\n"); for(j = 0; j < N; j++) plot[j] = 0; printf("okay1\n"); m = error(a,b); printf("%f\n",m); return 0; } float error(int a, int b){ float product = a*b; printf("%f\n",product); return product; } so the m = error(a,b) always gives 0 no matter what! Please help. I apologise for not cleaning this up...

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  • Maven does not resolve a local Grails plug-in

    - by Drew
    My goal is to take a Grails web application and build it into a Web ARchive (WAR file) using Maven, and the key is that it must populate the "plugins" folder without live access to the internet. An "out of the box" Grails webapp will already have the plugins folder populated with JAR files, but the maven build script should take care of populating it, just like it does for any traditional WAR projects (such as WEB-INF/lib/ if it's empty) This is an error when executing mvn grails:run-app with Grails 1.1 using Maven 2.0.10 and org.grails:grails-maven-plugin:1.0. (This "hibernate-1.1" plugin is needed to do GORM.) [INFO] [grails:run-app] Running pre-compiled script Environment set to development Plugin [hibernate-1.1] not installed, resolving.. Reading remote plugin list ... Error reading remote plugin list [svn.codehaus.org], building locally... Unable to list plugins, please check you have a valid internet connection: svn.codehaus.org Reading remote plugin list ... Error reading remote plugin list [plugins.grails.org], building locally... Unable to list plugins, please check you have a valid internet connection: plugins.grails.org Plugin 'hibernate' was not found in repository. If it is not stored in a configured repository you will need to install it manually. Type 'grails list-plugins' to find out what plugins are available. The build machine does not have access to the internet and must use an internal/enterprise repository, so this error is just saying that maven can't find the required artifact anywhere. That dependency is already included with the stock Grails software that's installed locally, so I just need to figure out how to get my POM file to unpackage that ZIP file into my webapp's "plugins" folder. I've tried installing the plugin manually to my local repository and making it an explicit dependency in POM.xml, but it's still not being recognized. Maybe you can't pull down grails plugins like you would a standard maven reference? mvn install:install-file -DgroupId=org.grails -DartifactId=grails-hibernate -Dversion=1.1 -Dpackaging=zip -Dfile=%GRAILS_HOME%/plugins/grails-hibernate-1.1.zip I can manually setup the Grails webapp from the command-line, which creates that local ./plugins folder properly. This is a step in the right direction, so maybe the question is: how can I incorporate this goal into my POM? mvn grails:install-plugin -DpluginUrl=%GRAILS_HOME%/plugins/grails-hibernate-1.1.zip Here is a copy of my POM.xml file, which was generated using an archetype. <?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.samples</groupId> <artifactId>sample-grails</artifactId> <packaging>war</packaging> <name>Sample Grails webapp</name> <properties> <sourceComplianceLevel>1.5</sourceComplianceLevel> </properties> <version>0.0.1-SNAPSHOT</version> <dependencies> <dependency> <groupId>org.grails</groupId> <artifactId>grails-crud</artifactId> <version>1.1</version> </dependency> <dependency> <groupId>org.grails</groupId> <artifactId>grails-gorm</artifactId> <version>1.1</version> </dependency> <dependency> <groupId>opensymphony</groupId> <artifactId>oscache</artifactId> <version>2.4</version> <exclusions> <exclusion> <groupId>commons-logging</groupId> <artifactId>commons-logging</artifactId> </exclusion> <exclusion> <groupId>javax.jms</groupId> <artifactId>jms</artifactId> </exclusion> <exclusion> <groupId>javax.servlet</groupId> <artifactId>servlet-api</artifactId> </exclusion> </exclusions> </dependency> <dependency> <groupId>hsqldb</groupId> <artifactId>hsqldb</artifactId> <version>1.8.0.7</version> </dependency> <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-log4j12</artifactId> <version>1.5.6</version> <scope>runtime</scope> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>jstl</artifactId> <version>1.2</version> </dependency> <!-- <dependency> <groupId>org.grails</groupId> <artifactId>grails-hibernate</artifactId> <version>1.1</version> <type>zip</type> </dependency> --> </dependencies> <build> <pluginManagement /> <plugins> <plugin> <groupId>org.grails</groupId> <artifactId>grails-maven-plugin</artifactId> <version>1.0</version> <extensions>true</extensions> <executions> <execution> <goals> <goal>init</goal> <goal>maven-clean</goal> <goal>validate</goal> <goal>config-directories</goal> <goal>maven-compile</goal> <goal>maven-test</goal> <goal>maven-war</goal> <goal>maven-functional-test</goal> </goals> </execution> </executions> </plugin> <plugin> <artifactId>maven-compiler-plugin</artifactId> <configuration> <source>${sourceComplianceLevel}</source> <target>${sourceComplianceLevel}</target> </configuration> </plugin> </plugins> </build> </project>

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  • Questions related to writing your own file downloader using multiple threads java

    - by Shekhar
    Hello In my current company, i am doing a PoC on how we can write a file downloader utility. We have to use socket programming(TCP/IP) for downloading the files. One of the requirements of the client is that a file(which will be large in size) should be transfered in chunks for example if we have a file of 5Mb size then we can have 5 threads which transfer 1 Mb each. I have written a small application which downloads a file. You can download the eclipe project from http://www.fileflyer.com/view/QM1JSC0 A brief explanation of my classes FileSender.java This class provides the bytes of file. It has a method called sendBytesOfFile(long start,long end, long sequenceNo) which gives the number of bytes. import java.io.File; import java.io.IOException; import java.util.zip.CRC32; import org.apache.commons.io.FileUtils; public class FileSender { private static final String FILE_NAME = "C:\\shared\\test.pdf"; public ByteArrayWrapper sendBytesOfFile(long start,long end, long sequenceNo){ try { File file = new File(FILE_NAME); byte[] fileBytes = FileUtils.readFileToByteArray(file); System.out.println("Size of file is " +fileBytes.length); System.out.println(); System.out.println("Start "+start +" end "+end); byte[] bytes = getByteArray(fileBytes, start, end); ByteArrayWrapper wrapper = new ByteArrayWrapper(bytes, sequenceNo); return wrapper; } catch (IOException e) { throw new RuntimeException(e); } } private byte[] getByteArray(byte[] bytes, long start, long end){ long arrayLength = end-start; System.out.println("Start : "+start +" end : "+end + " Arraylength : "+arrayLength +" length of source array : "+bytes.length); byte[] arr = new byte[(int)arrayLength]; for(int i = (int)start, j =0; i < end;i++,j++){ arr[j] = bytes[i]; } return arr; } public static long fileSize(){ File file = new File(FILE_NAME); return file.length(); } } Second Class is FileReceiver.java - This class receives the file. Small Explanation what this file does This class finds the size of the file to be fetched from Sender Depending upon the size of the file it finds the start and end position till the bytes needs to be read. It starts n number of threads giving each thread start,end, sequence number and a list which all the threads share. Each thread reads the number of bytes and creates a ByteArrayWrapper. ByteArrayWrapper objects are added to the list Then i have while loop which basically make sure that all threads have done their work finally it sorts the list based on the sequence number. then the bytes are joined, and a complete byte array is formed which is converted to a file. Code of File Receiver package com.filedownloader; import java.io.File; import java.io.IOException; import java.util.ArrayList; import java.util.Collections; import java.util.Comparator; import java.util.List; import java.util.zip.CRC32; import org.apache.commons.io.FileUtils; public class FileReceiver { public static void main(String[] args) { FileReceiver receiver = new FileReceiver(); receiver.receiveFile(); } public void receiveFile(){ long startTime = System.currentTimeMillis(); long numberOfThreads = 10; long filesize = FileSender.fileSize(); System.out.println("File size received "+filesize); long start = filesize/numberOfThreads; List<ByteArrayWrapper> list = new ArrayList<ByteArrayWrapper>(); for(long threadCount =0; threadCount<numberOfThreads ;threadCount++){ FileDownloaderTask task = new FileDownloaderTask(threadCount*start,(threadCount+1)*start,threadCount,list); new Thread(task).start(); } while(list.size() != numberOfThreads){ // this is done so that all the threads should complete their work before processing further. //System.out.println("Waiting for threads to complete. List size "+list.size()); } if(list.size() == numberOfThreads){ System.out.println("All bytes received "+list); Collections.sort(list, new Comparator<ByteArrayWrapper>() { @Override public int compare(ByteArrayWrapper o1, ByteArrayWrapper o2) { long sequence1 = o1.getSequence(); long sequence2 = o2.getSequence(); if(sequence1 < sequence2){ return -1; }else if(sequence1 > sequence2){ return 1; } else{ return 0; } } }); byte[] totalBytes = list.get(0).getBytes(); byte[] firstArr = null; byte[] secondArr = null; for(int i = 1;i<list.size();i++){ firstArr = totalBytes; secondArr = list.get(i).getBytes(); totalBytes = concat(firstArr, secondArr); } System.out.println(totalBytes.length); convertToFile(totalBytes,"c:\\tmp\\test.pdf"); long endTime = System.currentTimeMillis(); System.out.println("Total time taken with "+numberOfThreads +" threads is "+(endTime-startTime)+" ms" ); } } private byte[] concat(byte[] A, byte[] B) { byte[] C= new byte[A.length+B.length]; System.arraycopy(A, 0, C, 0, A.length); System.arraycopy(B, 0, C, A.length, B.length); return C; } private void convertToFile(byte[] totalBytes,String name) { try { FileUtils.writeByteArrayToFile(new File(name), totalBytes); } catch (IOException e) { throw new RuntimeException(e); } } } Code of ByteArrayWrapper package com.filedownloader; import java.io.Serializable; public class ByteArrayWrapper implements Serializable{ private static final long serialVersionUID = 3499562855188457886L; private byte[] bytes; private long sequence; public ByteArrayWrapper(byte[] bytes, long sequenceNo) { this.bytes = bytes; this.sequence = sequenceNo; } public byte[] getBytes() { return bytes; } public long getSequence() { return sequence; } } Code of FileDownloaderTask import java.util.List; public class FileDownloaderTask implements Runnable { private List<ByteArrayWrapper> list; private long start; private long end; private long sequenceNo; public FileDownloaderTask(long start,long end,long sequenceNo,List<ByteArrayWrapper> list) { this.list = list; this.start = start; this.end = end; this.sequenceNo = sequenceNo; } @Override public void run() { ByteArrayWrapper wrapper = new FileSender().sendBytesOfFile(start, end, sequenceNo); list.add(wrapper); } } Questions related to this code 1) Does file downloading becomes fast when multiple threads is used? In this code i am not able to see the benefit. 2) How should i decide how many threads should i create ? 3) Are their any opensource libraries which does that 4) The file which file receiver receives is valid and not corrupted but checksum (i used FileUtils of common-io) does not match. Whats the problem? 5) This code gives out of memory when used with large file(above 100 Mb) i.e. because byte array which is created. How can i avoid? I know this is a very bad code but i have to write this in one day -:). Please suggest any other good way to do this? Thanks Shekhar

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  • Where to find xmoov port to C#? (to make Http Pseudo Streaming from c# app)

    - by Ole Jak
    So I found this beautifull script for FLV video format Http Pseudo Streaming but in is in PHP ( found on http://stream.xmoov.com/ ) So does any one know opensource translations or can translate such PHP code into C#? <?php /* xmoov-php 1.0 Development version 0.9.3 beta by: Eric Lorenzo Benjamin jr. webmaster (AT) xmoov (DOT) com originally inspired by Stefan Richter at flashcomguru.com bandwidth limiting by Terry streamingflvcom (AT) dedicatedmanagers (DOT) com This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License. For more information, visit http://creativecommons.org/licenses/by-nc-sa/3.0/ For the full license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/legalcode or send a letter to Creative Commons, 543 Howard Street, 5th Floor, San Francisco, California, 94105, USA. */ // SCRIPT CONFIGURATION //------------------------------------------------------------------------------------------ // MEDIA PATH // // you can configure these settings to point to video files outside the public html folder. //------------------------------------------------------------------------------------------ // points to server root define('XMOOV_PATH_ROOT', ''); // points to the folder containing the video files. define('XMOOV_PATH_FILES', 'video/'); //------------------------------------------------------------------------------------------ // SCRIPT BEHAVIOR //------------------------------------------------------------------------------------------ //set to TRUE to use bandwidth limiting. define('XMOOV_CONF_LIMIT_BANDWIDTH', TRUE); //set to FALSE to prohibit caching of video files. define('XMOOV_CONF_ALLOW_FILE_CACHE', FALSE); //------------------------------------------------------------------------------------------ // BANDWIDTH SETTINGS // // these settings are only needed when using bandwidth limiting. // // bandwidth is limited my sending a limited amount of video data(XMOOV_BW_PACKET_SIZE), // in specified time intervals(XMOOV_BW_PACKET_INTERVAL). // avoid time intervals over 1.5 seconds for best results. // // you can also control bandwidth limiting via http command using your video player. // the function getBandwidthLimit($part) holds three preconfigured presets(low, mid, high), // which can be changed to meet your needs //------------------------------------------------------------------------------------------ //set how many kilobytes will be sent per time interval define('XMOOV_BW_PACKET_SIZE', 90); //set the time interval in which data packets will be sent in seconds. define('XMOOV_BW_PACKET_INTERVAL', 0.3); //set to TRUE to control bandwidth externally via http. define('XMOOV_CONF_ALLOW_DYNAMIC_BANDWIDTH', TRUE); //------------------------------------------------------------------------------------------ // DYNAMIC BANDWIDTH CONTROL //------------------------------------------------------------------------------------------ function getBandwidthLimit($part) { switch($part) { case 'interval' : switch($_GET[XMOOV_GET_BANDWIDTH]) { case 'low' : return 1; break; case 'mid' : return 0.5; break; case 'high' : return 0.3; break; default : return XMOOV_BW_PACKET_INTERVAL; break; } break; case 'size' : switch($_GET[XMOOV_GET_BANDWIDTH]) { case 'low' : return 10; break; case 'mid' : return 40; break; case 'high' : return 90; break; default : return XMOOV_BW_PACKET_SIZE; break; } break; } } //------------------------------------------------------------------------------------------ // INCOMING GET VARIABLES CONFIGURATION // // use these settings to configure how video files, seek position and bandwidth settings are accessed by your player //------------------------------------------------------------------------------------------ define('XMOOV_GET_FILE', 'file'); define('XMOOV_GET_POSITION', 'position'); define('XMOOV_GET_AUTHENTICATION', 'key'); define('XMOOV_GET_BANDWIDTH', 'bw'); // END SCRIPT CONFIGURATION - do not change anything beyond this point if you do not know what you are doing //------------------------------------------------------------------------------------------ // PROCESS FILE REQUEST //------------------------------------------------------------------------------------------ if(isset($_GET[XMOOV_GET_FILE]) && isset($_GET[XMOOV_GET_POSITION])) { // PROCESS VARIABLES # get seek position $seekPos = intval($_GET[XMOOV_GET_POSITION]); # get file name $fileName = htmlspecialchars($_GET[XMOOV_GET_FILE]); # assemble file path $file = XMOOV_PATH_ROOT . XMOOV_PATH_FILES . $fileName; # assemble packet interval $packet_interval = (XMOOV_CONF_ALLOW_DYNAMIC_BANDWIDTH && isset($_GET[XMOOV_GET_BANDWIDTH])) ? getBandwidthLimit('interval') : XMOOV_BW_PACKET_INTERVAL; # assemble packet size $packet_size = ((XMOOV_CONF_ALLOW_DYNAMIC_BANDWIDTH && isset($_GET[XMOOV_GET_BANDWIDTH])) ? getBandwidthLimit('size') : XMOOV_BW_PACKET_SIZE) * 1042; # security improved by by TRUI www.trui.net if (!file_exists($file)) { print('<b>ERROR:</b> xmoov-php could not find (' . $fileName . ') please check your settings.'); exit(); } if(file_exists($file) && strrchr($fileName, '.') == '.flv' && strlen($fileName) > 2 && !eregi(basename($_SERVER['PHP_SELF']), $fileName) && ereg('^[^./][^/]*$', $fileName)) { # stay clean @ob_end_clean(); @set_time_limit(0); # keep binary data safe set_magic_quotes_runtime(0); $fh = fopen($file, 'rb') or die ('<b>ERROR:</b> xmoov-php could not open (' . $fileName . ')'); $fileSize = filesize($file) - (($seekPos > 0) ? $seekPos + 1 : 0); // SEND HEADERS if(!XMOOV_CONF_ALLOW_FILE_CACHE) { # prohibit caching (different methods for different clients) session_cache_limiter("nocache"); header("Expires: Thu, 19 Nov 1981 08:52:00 GMT"); header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT"); header("Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0"); header("Pragma: no-cache"); } # content headers header("Content-Type: video/x-flv"); header("Content-Disposition: attachment; filename=\"" . $fileName . "\""); header("Content-Length: " . $fileSize); # FLV file format header if($seekPos != 0) { print('FLV'); print(pack('C', 1)); print(pack('C', 1)); print(pack('N', 9)); print(pack('N', 9)); } # seek to requested file position fseek($fh, $seekPos); # output file while(!feof($fh)) { # use bandwidth limiting - by Terry if(XMOOV_CONF_LIMIT_BANDWIDTH) { # get start time list($usec, $sec) = explode(' ', microtime()); $time_start = ((float)$usec + (float)$sec); # output packet print(fread($fh, $packet_size)); # get end time list($usec, $sec) = explode(' ', microtime()); $time_stop = ((float)$usec + (float)$sec); # wait if output is slower than $packet_interval $time_difference = $time_stop - $time_start; # clean up @flush(); @ob_flush(); if($time_difference < (float)$packet_interval) { usleep((float)$packet_interval * 1000000 - (float)$time_difference * 1000000); } } else { # output file without bandwidth limiting print(fread($fh, filesize($file))); } } } } ?>

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  • Object value not getting updated in the database using hibernate

    - by user1662917
    I am using Spring,hibernate,jsf with jquery in my application. I am inserting a Question object in the database through the hibernate save query . The question object contains id ,question,answertype and reference to a form object using form_id. Now I want to alter the values of Question object stored in the database by altering the value stored in the list of Question objects at the specified index position. If I alter the value in the list the value in the database is not getting altered by update query . Could you please advise. Question.java package com.otv.model; import java.io.Serializable; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.FetchType; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.JoinColumn; import javax.persistence.ManyToOne; import javax.persistence.Table; import org.apache.commons.lang.builder.ToStringBuilder; @Entity @Table(name = "questions") public class Question implements Serializable { @Id @GeneratedValue @Column(name = "id", unique = true, nullable = false) private int id; @Column(name = "question", nullable = false) private String text; @Column(name = "answertype", nullable = false) private String answertype; @ManyToOne(fetch = FetchType.EAGER) @JoinColumn(name = "form_id") private Form form; // @JoinColumn(name = "form_id") // private int formId; public Question() { } public Question(String text, String answertype) { this.text = text; this.answertype = answertype; } public int getId() { return id; } public void setId(int id) { this.id = id; } public String getQuestion() { return text; } public void setQuestion(String question) { this.text = question; } public String getAnswertype() { return answertype; } public void setAnswertype(String answertype) { this.answertype = answertype; } @Override public int hashCode() { final int prime = 31; int result = 1; result = prime * result + ((answertype == null) ? 0 : answertype.hashCode()); result = prime * result + id; result = prime * result + ((text == null) ? 0 : text.hashCode()); return result; } @Override public boolean equals(Object obj) { if (this == obj) return true; if (obj == null) return false; if (getClass() != obj.getClass()) return false; Question other = (Question) obj; if (answertype == null) { if (other.answertype != null) return false; } else if (!answertype.equals(other.answertype)) return false; if (id != other.id) return false; if (text == null) { if (other.text != null) return false; } else if (!text.equals(other.text)) return false; return true; } public void setForm(Form form) { this.form = form; } @Override public String toString() { return ToStringBuilder.reflectionToString(this); } } Form.java package com.otv.model; import java.io.Serializable; import java.util.ArrayList; import java.util.List; import javax.persistence.CascadeType; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.FetchType; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.OneToMany; import javax.persistence.Table; import org.apache.commons.lang.builder.ToStringBuilder; @Entity @Table(name = "FORM") public class Form implements Serializable { @Id @GeneratedValue @Column(name = "id", unique = true, nullable = false) private int id; @Column(name = "name", nullable = false) private String name; @Column(name = "description", nullable = false) private String description; @OneToMany(mappedBy = "form", fetch = FetchType.EAGER, cascade = CascadeType.ALL) List<Question> questions = new ArrayList<Question>(); public Form(String name) { super(); this.name = name; } public Form() { super(); } public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getDescription() { return description; } public void setDescription(String description) { this.description = description; } public List<Question> getQuestions() { return questions; } public void setQuestions(List<Question> formQuestions) { this.questions = formQuestions; } public void addQuestion(Question question) { questions.add(question); question.setForm(this); } public void removeQuestion(Question question) { questions.remove(question); question.setForm(this); } @Override public String toString() { return ToStringBuilder.reflectionToString(this); } public void replaceQuestion(int index, Question question) { Question prevQuestion = questions.get(index); // prevQuestion.setQuestion(question.getQuestion()); // prevQuestion.setAnswertype(question.getAnswertype()); question.setId(prevQuestion.getId()); question.setForm(this); questions.set(index, question); } } QuestionDAO.java package com.otv.user.dao; import java.util.List; import org.hibernate.SessionFactory; import com.otv.model.Question; public class QuestionDAO implements IQuestionDAO { private SessionFactory sessionFactory; public SessionFactory getSessionFactory() { return sessionFactory; } public void setSessionFactory(SessionFactory sessionFactory) { this.sessionFactory = sessionFactory; } public void addQuestion(Question question) { getSessionFactory().getCurrentSession().save(question); } public void deleteQuestion(Question question) { getSessionFactory().getCurrentSession().delete(question); } public void updateQuestion(Question question) { getSessionFactory().getCurrentSession().update(question); } public Question getQuestionById(int id) { List list = getSessionFactory().getCurrentSession().createQuery("from Questions where id=?") .setParameter(0, id).list(); return (Question) list.get(0); } }

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  • The 2010 JavaOne Java EE 6 Panel: Where We Are and Where We're Going

    - by janice.heiss(at)oracle.com
    An informative article, based on a 2010 JavaOne (San Francisco, California) panel session, surveys a variety of expert perspectives on Java EE 6.The panel, moderated by Oracle's Alexis Moussine-Pouchkine, consisted of:* Adam Bien, Consultant Author/ Speaker, adam-bien.com* Emmanuel Bernard, Principal Software Engineer, JBoss by Red Hat,* David Blevins, Senior Software Engineer, and co-founder of the OpenEJB project and a     founder of Apache Geronimo* Roberto Chinnici, Technical Staff Consulting Member, Oracle* Jim Knutson, Java EE Architect, IBM* Reza Rahman, Lead Engineer, Caucho Technology, Inc.,* Krasimir Semerdzhiev, Development Architect, SAP Labs BulgariaThe panel addressed such topics as Platform and API Adoption, Contexts and Dependency Injection (CDI), Java EE vs. Spring, the impact of Java EE 6 on tooling and testing, Java EE.next, along with a variety of audience questions. Read the entire article for the whole picture.

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  • IIS7.5 + Wordpress + Restrict Access to wp-login.php by client IP address

    - by JuanValdez
    I am moving from an Apache host to IIS. One of my sites in Wordpress (running Multi-site) which give me multiple blogs. I have moved all my rules from my .htaccess to the Microsoft URL ReWrite module. I have one section left that will not import. I want to restrict access to all instances of the file wp-login.php by Client IP address. In my .htaccess file I did the following: <Files wp-login.php> Order Deny,Allow Deny from all Allow from 192.168 </Files> Any smart ideas on how to accompish this in IIS7.5?

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  • Enabling SSL on apache2 causes address already in use error

    - by durron597
    My server works just fine on a normal apache2 install. Now, I'm trying to install subversion on this server using this guide: http://alephzarro.com/blog/2007/01/07/installation-of-subversion-on-ubuntu-with-apache-ssl-and-basicauth/ I get the following error: (98)Address already in use: make_sock: could not bind to address 0.0.0.0:443 When I do grep -rH 443 /etc/apache2/, I get results in two files: ports.conf and sites-enabled/default-ssl I tried it both with and without that last Listen 443 commented out, here's ports.conf: NameVirtualHost *:80 Listen 80 <IfModule mod_ssl.c> NameVirtualHost *:443 Listen 443 </IfModule> <IfModule mod_gnutls.c> Listen 443 </IfModule> #Listen 443 And the first few lines of default-ssl <IfModule mod_ssl.c> <VirtualHost *:443> ServerAdmin webmaster@localhost SSLEngine on SSLCertificateFile /this/isnt/relevant/probably.pem SSLProtocol all SSLCipherSuite HIGH:MEDIUM And netstat -an --inet | grep 443 returns nothing. Any ideas?

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  • Debugging Tips for Skinning

    - by Christian David Straub
    Another guest post by Jeanne Waldman.If you are developing a skin for your Fusion Application in JDeveloper you should know these tips.   1. Firebug is your friend 2. Uncompress the css style classes 3. CHECK_FILE_MODIFICATION so that you see your skinning changes right away 4. View the generated CSS File   1. Firebug is your friend Install Firebug (http://getfirebug.com/layout) into Firefox and use it to view your rendered jspx page in the browser. You can select the HTML dom nodes on your page and you can see the css styles applied to each dom node.   2. Uncompress the css style classes By default the styleclasses that are rendered are compressed. You may see style classes like class="x10" and class="x2e". But in your skin css file you have styleclasses like: af|inputText::content or af|panelBox::header   It is easier for you to develop a skin and debug a skin with Firebug if you see the uncompressed styleclasses. To do this, a. open web.xml b. add   <context-param>     <param-name>org.apache.myfaces.trinidad.DISABLE_CONTENT_COMPRESSION</param-name>     <param-value>true</param-value>   </context-param> c. save d. restart the server and re-run your page.   3. CHECK_FILE_MODIFICATION so that you see your skinning changes right away   For performance sake the ADF Faces framework does not check if you skin .css file has changed on every render. But this is exactly what you want to happen when you are developing or debugging a skin. You want your changes to get noticed right away, without restarting the server.   To do this, a. open web.xml b. add   <context-param>     <description>If this parameter is true, there will be an automatic check of the modification date of your JSPs, and saved state will be discarded when JSP's change. It will also automatically check if your skinning css files have changed without you having to restart the server. This makes development easier, but adds overhead. For this reason this parameter should be set to false when your application is deployed.</description>     <param-name>org.apache.myfaces.trinidad.CHECK_FILE_MODIFICATION</param-name>     <param-value>false</param-value>   </context-param> c. save d. restart the server and re-run your page. e. from then on, you can change your skin's .css file, save it and refresh your page and you should see the changes right away   4. View the generated CSS File   There are different ways to view the generated CSS File which is your skin's css file merged in with all the skins it extends and processed and generated to the filesystem and linked to your generated html page. One way is to view it with Firebug. The problem with this approach is you might see something that is a little different than the actual css file because Firebug may do some extra processing. I like to view the generated css file by: Right click on your page in the browser 

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