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  • Brightness is reset to Maximum on every Restart

    - by Bhargav
    The brightness of my laptop is reset to Max on every restart. I tried the solution provided at this website but had no luck. http://ubuntuguide.net/how-to-save-screen-brightness-settings-in-ubuntu-12-04-laptop/ This command cat /sys/class/backlight/acpi_video0/max_brightness Returns cat: /sys/class/backlight/acpi_video0/max_brightness: No such file or directory Then I go on to find that I don't have any folder named acpi_video0 but a folder called intel_backlight Every time I increase or decrease the brightness using the Brightness Control Keys the "brightness" and the "actual_brightness" values get updated. Is there any method I could follow to set the brightness to a fixed value on everyboot and vary it as and when I need it using the Brightness Control Keys.

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  • Creating widgets using GtkBuilder

    - by user72943
    I am using Glade to design a Box with widgets and then load these widgets into my UI at run-time. To create each Box with widgets at run-time, I create a new GtkBuilder, call add_from_string passing in the text from the .ui file Glade creates, and then use the object returned from get_object("box1") in the UI. I know I could create the widgets with code, but for now, I'd like to use the .ui files Glade creates. It seems inefficient though to instantiate a new GtkBuilder object and the wasted Window object for every Box I want to create. Is there a more efficient method to load .ui files without creating a new GtkWidget object and wasted Window object? Thanks, Vance

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  • Design Patterns and their most common uses for them [closed]

    - by cable729
    Possible Duplicate: What are some programming design patterns that are useful in game development? As I'm returning to game dev, I've realized that I've lost a lot of the knowledge I had before. So now I'm looking at design patterns that I can use for my next project. One design pattern that I've seen a lot is the 'composition method,' which uses actors and components. Is that the right name for it? I'd like to look more at this and see what the advantages/pitfalls are. So what design patterns are out there, and what are the advantages/disadvantages to them?

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  • Can this word search algorithm be made faster?

    - by Ashwin Singh
    Problem: Find a match of word S in text T Given: S and T are part of spoken and written English. Example: Match 'Math' in 'I love Mathematics' NOTE: Ignore CASES. My algorithm: STEP 1) Convert S, T to char[] STEP 2) for i=0, i < T.length , i++ STEP 3) for j=S.length-1, j>0 , j-- STEP 3 is the magic, instead of going about matching M,A,T,H, this matches M, H, T and finally A. This helps in eliminating a lot of possible partial matches. For example, if I go sequentially like M A as in Boyer Moore's method ... it can match Matter, Mass, Matchstick etc. using M _ _ H will bring down size of partial matches. STEP 4) if S[j]!=T[i] -> break; else if j==i -> PRINT MATCH

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  • How do I morph between meshes that have different vertex counts?

    - by elijaheac
    I am using MeshMorpher from the Unify wiki in my Unity project, and I want to be able to transform between arbitrary meshes. This utility works best when there are an equal number of vertices between the two meshes. Is there some way to equalize the vertex count between a set of meshes? I don't mean that this would reduce the vertex count of a mesh, but would rather add redundant vertices to any meshes with smaller counts. However, if there is an alternate method of handling this (other than increasing vertices), I would like to know.

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  • How can I gain access to a player instance in a Minecraft mod?

    - by Andrew Graber
    I'm creating Minecraft mod with a pickaxe that takes away experience when you break a block. The method for taking away experience from a player is addExperience on EntityPlayer, so I need to get an instance of EntityPlayer for the player using my pickaxe when the pickaxe breaks a block, so that I can remove the appropriate amount of experience. My pickaxe class currently looks like this: public class ExperiencePickaxe extends ItemPickaxe { public ExperiencePickaxe(int ItemID, EnumToolMaterial material){ super(ItemID, material); } public boolean onBlockDestroyed(ItemStack par1ItemStack, World par2World, int par3, int par4, int par5, int par6, EntityLiving par7EntityLiving) { if ((double)Block.blocksList[par3].getBlockHardness(par2World, par4, par5, par6) != 0.0D) { EntityPlayer e = new EntityPlayer(); // create an instance e.addExperience(-1); } return true; } } Obviously, I cannot actually create a new EntityPlayer since it is an abstract class. How can I get access to the player using my pickaxe?

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  • Clarification of "avoid if-else" advice [duplicate]

    - by deviDave
    This question already has an answer here: Elegant ways to handle if(if else) else 21 answers The experts in clean code advise not to use if/else since it's creating an unreadable code. They suggest rather using IF and not to wait till the end of a method without real need. Now, this if/else advice confuses me. Do they say that I should not use if/else at all (!) or to avoid if/else nesting? Also, if they refer to the nesting of if/else, should I not do even a single nesting or I should limit it to max 2 nestings (as some recommends)? When I say single nesting, I mean this: if (...) { if (...) { } else { } } else { } EDIT Also tools like Resharper will suggest reformatting if/else statements. It usually concerts them to if stand-alone statement, and sometimes even to ternary expression.

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  • How to work with scenes in a 2D game

    - by Anearion
    I'm a java/android programmer, but I don't have any experience in game programming, I'm already reading proper books, like "Pro Android Games", but my concerns are more about the ideas behind game programming than the techniques themselves. I'm working on a 2D game, something like Cluedo to let you understand the genre. I would like to know how should I act with the "scenes", for example, a room with a desk, TV, windows and a lamp. I need to make some items tappable and others not. Is it common to use one image (invisible to the user) with every different item a different color, then call the getColor() method on the image? Or use one image as background, and separate images for all the items? If the latter, how can I set the positioning? and should I use imageView or imageButton? I'm sorry if those are really low quality questions, but as "outsider" ( I'm 23 and still finishing my university ) it's pretty hard learn alone.

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  • Silverlight 4 Twitter Client - Part 2

    - by Max
    We will create a few classes now to help us with storing and retrieving user credentials, so that we don't ask for it every time we want to speak with Twitter for getting some information. Now the class to sorting out the credentials. We will have this class as a static so as to ensure one instance of the same. This class is mainly going to include a getter setter for username and password, a method to check if the user if logged in and another one to log out the user. You can get the code here. Now let us create another class to facilitate easy retrieval from twitter xml format results for any queries we make. This basically involves just creating a getter setter for all the values that you would like to retrieve from the xml document returned. You can get the format of the xml document from here. Here is what I've in my Status.cs data structure class. using System; using System.Net; using System.Windows; using System.Windows.Controls; using System.Windows.Documents; using System.Windows.Ink; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Animation; using System.Windows.Shapes;  namespace MaxTwitter.Classes { public class Status { public Status() {} public string ID { get; set; } public string Text { get; set; } public string Source { get; set; } public string UserID { get; set; } public string UserName { get; set; } } }  Now let us looking into implementing the Login.xaml.cs, first thing here is if the user is already logged in, we need to redirect the user to the homepage, this we can accomplish using the event OnNavigatedTo, which is fired when the user navigates to this particular Login page. Here you utilize the navigate to method of NavigationService to goto a different page if the user is already logged in. if (GlobalVariable.isLoggedin())         this.NavigationService.Navigate(new Uri("/Home", UriKind.Relative));  On the submit button click event, add the new event handler, which would save the perform the WebClient request and download the results as xml string. WebRequest.RegisterPrefix("https://", System.Net.Browser.WebRequestCreator.ClientHttp);  The following line allows us to create a web client to create a web request to a url and get back the string response. Something that came as a great news with SL 4 for many SL developers.   WebClient myService = new WebClient(); myService.AllowReadStreamBuffering = true; myService.UseDefaultCredentials = false; myService.Credentials = new NetworkCredential(TwitterUsername.Text, TwitterPassword.Password);  Here in the following line, we add an event that has to be fired once the xml string has been downloaded. Here you can do all your XLINQ stuff.   myService.DownloadStringCompleted += new DownloadStringCompletedEventHandler(TimelineRequestCompleted);   myService.DownloadStringAsync(new Uri("https://twitter.com/statuses/friends_timeline.xml"));  Now let us look at implementing the TimelineRequestCompleted event. Here we are not actually using the string response we get from twitter, I just use it to ensure the user is authenticated successfully and then save the credentials and redirect to home page. public void TimelineRequestCompleted(object sender, System.Net.DownloadStringCompletedEventArgs e) { if (e.Error != null) { MessageBox.Show("This application must be installed first"); }  If there is no error, we can save the credentials to reuse it later.   else { GlobalVariable.saveCredentials(TwitterUsername.Text, TwitterPassword.Password); this.NavigationService.Navigate(new System.Uri("/Home", UriKind.Relative)); } } Ok so now login page is done. Now the main thing – running this application. This credentials stuff would only work, if the application is run out of the browser. So we need fiddle with a few Silverlioght project settings to enable this. Here is how:    Right click on Silverlight > properties then check the "Enable running application out of browser".    Then click on Out-Of-Browser settings and check "Require elevated trust…" option. That's it, all done to run. Now press F5 to run the application, fix the errors if any. Then once the application opens up in browser with the login page, right click and choose install.  Once you install, it would automatically run and you can login and can see that you are redirected to the Home page. Here are the files that are related to this posts. We will look at implementing the Home page, etc… in the next post. Please post your comments and feedbacks; it would greatly help me in improving my posts!  Thanks for your time, catch you soon.

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  • Collision Error

    - by Manji
    I am having trouble with collision detection part of the game. I am using touch events to fire the gun as you will see in the video. Note, the android icon is a temporary graphic for the bullets When ever the user touches (represented by clicks in the video)the bullet appears and kills random sprites. As you can see it never touches the sprites it kills or kill the sprites it does touch. My Question is How do I fix it, so that the sprite dies when the bullet hits it? Collision Code snippet: //Handles Collision private void CheckCollisions(){ synchronized(mSurfaceHolder){ for (int i = sprites.size() - 1; i >= 0; i--){ Sprite sprite = sprites.get(i); if(sprite.isCollision(bullet)){ sprites.remove(sprite); mScore++; if(sprites.size() == 0){ mLevel = mLevel +1; currentLevel++; initLevel(); } break; } } } } Sprite Class Code Snippet: //bounding box left<right and top>bottom int left ; int right ; int top ; int bottom ; public boolean isCollision(Beam other) { // TODO Auto-generated method stub if(this.left>other.right || other.left<other.right)return false; if(this.bottom>other.top || other.bottom<other.top)return false; return true; } EDIT 1: Sprite Class: public class Sprite { // direction = 0 up, 1 left, 2 down, 3 right, // animation = 3 back, 1 left, 0 front, 2 right int[] DIRECTION_TO_ANIMATION_MAP = { 3, 1, 0, 2 }; private static final int BMP_ROWS = 4; private static final int BMP_COLUMNS = 3; private static final int MAX_SPEED = 5; private HitmanView gameView; private Bitmap bmp; private int x; private int y; private int xSpeed; private int ySpeed; private int currentFrame = 0; private int width; private int height; //bounding box left<right and top>bottom int left ; int right ; int top ; int bottom ; public Sprite(HitmanView gameView, Bitmap bmp) { this.width = bmp.getWidth() / BMP_COLUMNS; this.height = bmp.getHeight() / BMP_ROWS; this.gameView = gameView; this.bmp = bmp; Random rnd = new Random(); x = rnd.nextInt(gameView.getWidth() - width); y = rnd.nextInt(gameView.getHeight() - height); xSpeed = rnd.nextInt(MAX_SPEED * 2) - MAX_SPEED; ySpeed = rnd.nextInt(MAX_SPEED * 2) - MAX_SPEED; } private void update() { if (x >= gameView.getWidth() - width - xSpeed || x + xSpeed <= 0) { xSpeed = -xSpeed; } x = x + xSpeed; if (y >= gameView.getHeight() - height - ySpeed || y + ySpeed <= 0) { ySpeed = -ySpeed; } y = y + ySpeed; currentFrame = ++currentFrame % BMP_COLUMNS; } public void onDraw(Canvas canvas) { update(); int srcX = currentFrame * width; int srcY = getAnimationRow() * height; Rect src = new Rect(srcX, srcY, srcX + width, srcY + height); Rect dst = new Rect(x, y, x + width, y + height); canvas.drawBitmap(bmp, src, dst, null); } private int getAnimationRow() { double dirDouble = (Math.atan2(xSpeed, ySpeed) / (Math.PI / 2) + 2); int direction = (int) Math.round(dirDouble) % BMP_ROWS; return DIRECTION_TO_ANIMATION_MAP[direction]; } public boolean isCollision(float x2, float y2){ return x2 > x && x2 < x + width && y2 > y && y2 < y + height; } public boolean isCollision(Beam other) { // TODO Auto-generated method stub if(this.left>other.right || other.left<other.right)return false; if(this.bottom>other.top || other.bottom<other.top)return false; return true; } } Bullet Class: public class Bullet { int mX; int mY; private Bitmap mBitmap; //bounding box left<right and top>bottom int left ; int right ; int top ; int bottom ; public Bullet (Bitmap mBitmap){ this.mBitmap = mBitmap; } public void draw(Canvas canvas, int mX, int mY) { this.mX = mX; this.mY = mY; canvas.drawBitmap(mBitmap, mX, mY, null); } }

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  • Custom extensible file format for 2d tiled maps

    - by Christian Ivicevic
    I have implemented much of my game logic right now, but still create my maps with nasty for-loops on-the-fly to be able to work with something. Now I wanted to move on and to do some research on how to (un)serialize this data. (I do not search for a map editor - I am speaking of the map file itself) For now I am looking for suggestions and resources, how to implement a custom file format for my maps which should provide the following functionality (based on MoSCoW method): Must have Extensibility and backward compatibility Handling of different layers Metadata on whether a tile is solid or can be passed through Special serialization of entities/triggers with associated properties/metadata Could have Some kind of inclusion of the tileset to prevent having scattered files/tilesets I am developing with C++ (using SDL) and targetting only Windows. Any useful help, tips, suggestions, ... would be appreciated!

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  • C# replacing out parameters with struct

    - by Jonathan
    I'm encountering a lot of methods in my project that have a bunch of out parameters embedded in them and its making it cumbersome to call the methods as I have to start declaring the variables before calling the methods. As such, I would like to refactor the code to return a struct instead and was wondering if this is a good idea. One of the examples from an interface: void CalculateFinancialReturnTotals(FinancialReturn fr, out decimal expenses, out decimal revenue, out decimal levyA, out decimal levyB, out decimal profit, out decimal turnover, out string message) and if I was to refactor that, i would be putting all the out parameters in the struct such that the method signature is much simpler as below. [structName] CalculateFinancialReturnTotals(FinancialReturn fr); Please advise.

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  • Alternative way of developing for ASP.NET to WebForms - Any problems with this?

    - by John
    So I have been developing in ASP.NET WebForms for some time now but often get annoyed with all the overhead (like ViewState and all the JavaScript it generates), and the way WebForms takes over a lot of the HTML generation. Sometimes I just want full control over the markup and produce efficient HTML of my own so I have been experimenting with what I like to call HtmlForms. Essentially this is using ASP.NET WebForms but without the form runat="server" tag. Without this tag, ASP.NET does not seem to add anything to the page at all. From some basic tests it seems that it runs well and you still have the ability to use code-behind pages, and many ASP.NET controls such as repeaters. Of course without the form runat="server" many controls won't work. A post at Enterprise Software Development lists the controls that do require the tag. From that list you will see that all of the form elements like TextBoxes, DropDownLists, RadioButtons, etc cannot be used. Instead you use normal HTML form controls. But how do you access these HTML controls from the code behind? Retrieving values on post back is easy, you just use Request.QueryString or Request.Form. But passing data to the control could be a little messy. Do you use a ASP.NET Literal control in the value field or do you use <%= value % in the markup page? I found it best to add runat="server" to my HTML controls and then you can access the control in your code-behind like this: ((HtmlInputText)txtName).Value = "blah"; Here's a example that shows what you can do with a textbox and drop down list: Default.aspx <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="NoForm.Default" %> <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="NoForm.Default" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN""http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title></title> </head> <body> <form action="" method="post"> <label for="txtName">Name:</label> <input id="txtName" name="txtName" runat="server" /><br /> <label for="ddlState">State:</label> <select id="ddlState" name="ddlState" runat="server"> <option value=""></option> </select><br /> <input type="submit" value="Submit" /> </form> </body> </html> Default.aspx.cs using System; using System.Web.UI.HtmlControls; using System.Web.UI.WebControls; namespace NoForm { public partial class Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { //Default values string name = string.Empty; string state = string.Empty; if (Request.RequestType == "POST") { //If form submitted (post back) name = Request.Form["txtName"]; state = Request.Form["ddlState"]; //Server side form validation would go here //and actions to process form and redirect } ((HtmlInputText)txtName).Value = name; ((HtmlSelect)ddlState).Items.Add(new ListItem("ACT")); ((HtmlSelect)ddlState).Items.Add(new ListItem("NSW")); ((HtmlSelect)ddlState).Items.Add(new ListItem("NT")); ((HtmlSelect)ddlState).Items.Add(new ListItem("QLD")); ((HtmlSelect)ddlState).Items.Add(new ListItem("SA")); ((HtmlSelect)ddlState).Items.Add(new ListItem("TAS")); ((HtmlSelect)ddlState).Items.Add(new ListItem("VIC")); ((HtmlSelect)ddlState).Items.Add(new ListItem("WA")); if (((HtmlSelect)ddlState).Items.FindByValue(state) != null) ((HtmlSelect)ddlState).Value = state; } } } As you can see, you have similar functionality to ASP.NET server controls but more control over the final markup, and less overhead like ViewState and all the JavaScript ASP.NET adds. Interestingly you can also use HttpPostedFile to handle file uploads using your own input type="file" control (and necessary form enctype="multipart/form-data"). So my question is can you see any problems with this method, and any thoughts on it's usefulness? I have further details and tests on my blog.

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  • Area of testing

    - by ?????? ??????????
    I'm trying to understand which part of my code I should to test. I have some code. Below is example of this code, just to understand the idea. Depends of some parametrs I put one or another currency to "Event" and return his serialization in the controller. Which part of code I should to test? Just the final serialization, or only "Event" or every method: getJson, getRows, fillCurrency, setCurrency? class Controller { public function getJson() { $rows = $eventManager->getRows(); return new JsonResponse($rows); } } class EventManager { public function getRows() { //some code here if ($parameter == true) { $this->fillCurrency($event, $currency); } } public function fillCurrency($event, $currency) { //some code here if ($parameters == true) { $event->setCurrency($currency); } } } class Event { public function setCurrency($currency) { $this->updatedAt = new Datetime(); $this->currency = $currency; } }

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  • Inconsistencies in Health Monitoring Between WebForms and MVC

    As I have written and spoken on numerous occasions, Health Monitoring happens to be one of my favorite features in ASP.NET. In WebForms, it's a path well trodden. However, while building Morts & Elvises with MVC2, I ran into a strange inconsistency, which I'd like to describe here. WebForms Whenever a WebForm throws an unhandled exception, at the very least the error is written to the system's even log. Suppose we have this silly simple page method: protected override void OnLoad...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Cant install wine1.5 13.04

    - by Drew S
    So I tried to install wine 1.5 a few times, I got 1.4 installed, and 1.6 installed oddly enough, I completely removed and purged all wine and still nothing. I installed ia32-lib and still nothing, tried installing from synaptic, ubuntu software center, and apt-get method. I get this error from apt-get in the terminal Reading package lists... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help resolve the situation: The following packages have unmet dependencies: wine1.5 : Depends: wine1.6 but it is not going to be installed E: Unable to correct problems, you have held broken packages. The particular windows program I want to install is confirmed working in 1.5(have it working on laptop)

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  • WWW.yoursite.com or HTTP://yoursite.com which one is futureproof?

    - by Sam
    http://yoursite.com www.yoursite.com http://www.yoursite.com yoursite.com Which of these would you choose as your favourite to work with, if you were to make a site for 2011 and beyond, which domainname would you provide to clients, websites linking to you, your letterhead, contact cards. Why one OR other? Which to avoid? Thinking of the following aspects: validity, correctly loading URL audience, most geeks know http://, most seniors/clients don't easiest to remember / URL as a brand misspellings by user input (in mobile phone or desktop browser) browsers not understanding protocol-less links total length of chars for easy user input method of peferance by major search engines/social media sites consistency sothat links dont fragment but all point to the same

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  • Best way to prevent UIPanGestureRecognizer from firing when moving sprites in cocos2d

    - by cjroebuck
    Im using UIPanGestureRecognizer in my cocos2d game to do drag and drop of sprites. I have a row of sprites and when I drag a sprite on top of another one, the sprite underneath it and any other sprites between should shift left or right out of the way to allow space to drop the currently selected sprite. This is working ok, however, if I am too quick at dragging the sprite around the screen, this triggers another round of the UIPanGestureRecognizer's callback method, and screws up the logic, as the sprites are in-between shifting. I need a way to freeze the callback from firing, whilst the other sprites are shifting, then once they have finished moving, re-enable the callback to fire. Whats the best way to do this?

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  • Computer Networks UNISA - Chap 8 &ndash; Wireless Networking

    - by MarkPearl
    After reading this section you should be able to Explain how nodes exchange wireless signals Identify potential obstacles to successful transmission and their repercussions, such as interference and reflection Understand WLAN architecture Specify the characteristics of popular WLAN transmission methods including 802.11 a/b/g/n Install and configure wireless access points and their clients Describe wireless MAN and WAN technologies, including 802.16 and satellite communications The Wireless Spectrum All wireless signals are carried through the air by electromagnetic waves. The wireless spectrum is a continuum of the electromagnetic waves used for data and voice communication. The wireless spectrum falls between 9KHZ and 300 GHZ. Characteristics of Wireless Transmission Antennas Each type of wireless service requires an antenna specifically designed for that service. The service’s specification determine the antenna’s power output, frequency, and radiation pattern. A directional antenna issues wireless signals along a single direction. An omnidirectional antenna issues and receives wireless signals with equal strength and clarity in all directions The geographical area that an antenna or wireless system can reach is known as its range Signal Propagation LOS (line of sight) uses the least amount of energy and results in the reception of the clearest possible signal. When there is an obstacle in the way, the signal may… pass through the object or be obsrobed by the object or may be subject to reflection, diffraction or scattering. Reflection – waves encounter an object and bounces off it. Diffraction – signal splits into secondary waves when it encounters an obstruction Scattering – is the diffusion or the reflection in multiple different directions of a signal Signal Degradation Fading occurs as a signal hits various objects. Because of fading, the strength of the signal that reaches the receiver is lower than the transmitted signal strength. The further a signal moves from its source, the weaker it gets (this is called attenuation) Signals are also affected by noise – the electromagnetic interference) Interference can distort and weaken a wireless signal in the same way that noise distorts and weakens a wired signal. Frequency Ranges Older wireless devices used the 2.4 GHZ band to send and receive signals. This had 11 communication channels that are unlicensed. Newer wireless devices can also use the 5 GHZ band which has 24 unlicensed bands Narrowband, Broadband, and Spread Spectrum Signals Narrowband – a transmitter concentrates the signal energy at a single frequency or in a very small range of frequencies Broadband – uses a relatively wide band of the wireless spectrum and offers higher throughputs than narrowband technologies The use of multiple frequencies to transmit a signal is known as spread-spectrum technology. In other words a signal never stays continuously within one frequency range during its transmission. One specific implementation of spread spectrum is FHSS (frequency hoping spread spectrum). Another type is known as DSS (direct sequence spread spectrum) Fixed vs. Mobile Each type of wireless communication falls into one of two categories Fixed – the location of the transmitted and receiver do not move (results in energy saved because weaker signal strength is possible with directional antennas) Mobile – the location can change WLAN (Wireless LAN) Architecture There are two main types of arrangements Adhoc – data is sent directly between devices – good for small local devices Infrastructure mode – a wireless access point is placed centrally, that all devices connect with 802.11 WLANs The most popular wireless standards used on contemporary LANs are those developed by IEEE’s 802.11 committee. Over the years several distinct standards related to wireless networking have been released. Four of the best known standards are also referred to as Wi-Fi. They are…. 802.11b 802.11a 802.11g 802.11n These four standards share many characteristics. i.e. All 4 use half duplex signalling Follow the same access method Access Method 802.11 standards specify the use of CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) to access a shared medium. Using CSMA/CA before a station begins to send data on an 802.11 network, it checks for existing wireless transmissions. If the source node detects no transmission activity on the network, it waits a brief period of time and then sends its transmission. If the source does detect activity, it waits a brief period of time before checking again. The destination node receives the transmission and, after verifying its accuracy, issues an acknowledgement (ACT) packet to the source. If the source receives the ACK it assumes the transmission was successful, – if it does not receive an ACK it assumes the transmission failed and sends it again. Association Two types of scanning… Active – station transmits a special frame, known as a prove, on all available channels within its frequency range. When an access point finds the probe frame, it issues a probe response. Passive – wireless station listens on all channels within its frequency range for a special signal, known as a beacon frame, issued from an access point – the beacon frame contains information necessary to connect to the point. Re-association occurs when a mobile user moves out of one access point’s range and into the range of another. Frames Read page 378 – 381 about frames and specific 802.11 protocols Bluetooth Networks Sony Ericson originally invented the Bluetooth technology in the early 1990s. In 1998 other manufacturers joined Ericsson in the Special Interest Group (SIG) whose aim was to refine and standardize the technology. Bluetooth was designed to be used on small networks composed of personal communications devices. It has become popular wireless technology for communicating among cellular telephones, phone headsets, etc. Wireless WANs and Internet Access Refer to pages 396 – 402 of the textbook for details.

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  • Web application deployment and Dependencies

    - by Reith
    I have a free software web application that using other free software scripts for appearance. I have trouble to decide whether should I copy source code of used scripts to my project main repository or list them as dependencies and ask user to install them himself? Since some of scripts solving browser compatibilities issues and I'm not a good web designer (i hate to check my web site on IE to see compatibility) using the newest version of scripts is preferable and second solution works here. But it has problem with scripts aren't backward-compatible with versions I've used them for development. Maybe another method is well-known for this issues that I don't know them.

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  • What are the basic skills a beginner JavaScript programmer should have?

    - by Sanford
    In NYC, we are working on creating a collaborative community programming environment and trying to segment out software engineers into differing buckets. At present, we are trying to define: Beginners Intermediates Advanced Experts (and/or Masters) Similar to an apprenticeship, you would need to demonstrate specific skills to achieve different levels. Right now, we have identified beginner programming skills as: Object - method, attributes, inheritance Variable - math, string, array, boolean - all are objects Basic arithmetic functions - precedence of functions String manipulation Looping - flow control Conditionals - boolean algebra This is a first attempt, and it is a challenge since we know the natural tension between programming and software engineering. How would you create such a skills-based ranking for JavaScript in this manner? For example, what would be the beginner JavaScript skills that you would need to have to advance to the intermediate training? And so on.

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  • Help to understand the abstract factory pattern

    - by Chobeat
    I'm learning the 23 design patterns of the GoF. I think I've found a way to understand and simplify how the Abstract Factory works but I would like to know if this is a correct assumption or if I am wrong. What I want to know is if we can see the result of the Abstract Factory method as a matrix of possible products where there's a Product for every "Concrete Factory" x "AbstractProduct" where the Concrete Factory is a single implementation among the implementations of an AbstractFactory and an AbstractProduct is an interface among the interfaces to create Products. Is this correct or am I missing something?

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  • Evolution has no access to couchdb

    - by berkes
    Evolution gives the error "Cannot open addressbook". "We were unable to open this addressbook. This either means you have entered an incorrect URI, or the server is unreachable". "Details: Operation not permitted". (rough translation from Dutch). Enabling verbose logging in (desktop)couchdb tells me roughly the same: [info] [<0.7875.1>] 127.0.0.1 - - 'PUT' /contacts/ 400 [debug] [<0.7875.1>] httpd 400 error response: {"error":"invalid_consumer","reason":"Invalid consumer (key or signature method)."} It seems that evolution tries to fetch the contacts, then couchdb denies access, and then evolution fails to do a proper oauth. This is on Ubuntu 10.10, with its default dektopcouch 1.0.1. Any hints on where to start would be most appreciated :)

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  • Code refactoring with Visual Studio 2010 Part-4

    - by Jalpesh P. Vadgama
    I have been writing few post with code refactoring features in Visual Studio 2010. This post also will be part of series and this post will be last of the series. In this post I am going explain two features 1) Encapsulate Field and 2) Extract Interface. Let’s explore both features in details. Encapsulate Field: This is a nice code refactoring feature provides by Visual Studio 2010. With help of this feature we can create properties from the existing private field of the class. Let’s take a simple example of Customer Class. In that I there are two private field called firstName and lastName. Below is the code for the class. public class Customer { private string firstName; private string lastName; public string Address { get; set; } public string City { get; set; } } Now lets encapsulate first field firstName with Encapsulate feature. So first select that field and goto refactor menu in Visual Studio 2010 and click on Encapsulate Field. Once you click that a dialog box will appear like following. Now once you click OK a preview dialog box will open as we have selected preview reference changes. I think its a good options to check that option to preview code that is being changed by IDE itself. Dialog will look like following. Once you click apply it create a new property called FirstName. Same way I have done for the lastName and now my customer class code look like following. public class Customer { private string firstName; public string FirstName { get { return firstName; } set { firstName = value; } } private string lastName; public string LastName { get { return lastName; } set { lastName = value; } } public string Address { get; set; } public string City { get; set; } } So you can see that its very easy to create properties with existing fields and you don’t have to change anything there in code it will change all the stuff itself. Extract Interface: When you are writing software prototype and You don’t know the future implementation of that then its a good practice to use interface there. I am going to explain here that How we can extract interface from the existing code without writing a single line of code with the help of code refactoring feature of Visual Studio 2010. For that I have create a Simple Repository class called CustomerRepository with three methods like following. public class CustomerRespository { public void Add() { // Some code to add customer } public void Update() { //some code to update customer } public void Delete() { //some code delete customer } } In above class there are three method Add,Update and Delete where we are going to implement some code for each one. Now I want to create a interface which I can use for my other entities in project. So let’s create a interface from the above class with the help of Visual Studio 2010. So first select class and goto refactor menu and click Extract Interface. It will open up dialog box like following. Here I have selected all the method for interface and Once I click OK then it will create a new file called ICustomerRespository where it has created a interface. Just like following. Here is a code for that interface. using System; namespace CodeRefractoring { interface ICustomerRespository { void Add(); void Delete(); void Update(); } } Now let's see the code for the our class. It will also changed like following to implement the interface. public class CustomerRespository : ICustomerRespository { public void Add() { // Some code to add customer } public void Update() { //some code to update customer } public void Delete() { //some code delete customer } } Isn't that great we have created a interface and implemented it without writing a single line of code. Hope you liked it. Stay tuned for more.. Till that Happy Programming.

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  • EJB Lifecycle and Relation to WARs

    - by Adam Tannon
    I've been reading up on EJBs (3.x) and believe I understand the basics. This question is a "call for confirmation" that I have interpreted the Java EE docs correctly and that I understand these fundamental concepts: An EJB is to an App Container as a Web App (WAR) is to a Web Container Just like you deploy a WAR to a Web Container, and that container manages your WAR's life cycle, you deploy an EJB to an App Container, and the container manages your EJB's life cycle When the App Container fires up and deploys an EJB, it is given a unique "identifier" and URL that can be used by JNDI to look up the EJB from another tier (like the web tier) So, when your web app wants to invoke one of your EJB's methods, it looks the EJB up using some kind of service locator (JNDI) and invoke the method that way Am I on-track or way off-base here? Please correct me & clarify for me if any of these are incorrect. Thanks in advance!

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