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  • Checksum Transformation

    The Checksum Transformation computes a hash value, the checksum, across one or more columns, returning the result in the Checksum output column. The transformation provides functionality similar to the T-SQL CHECKSUM function, but is encapsulated within SQL Server Integration Services, for use within the pipeline without code or a SQL Server connection. As featured in The Microsoft Data Warehouse Toolkit by Joy Mundy and Warren Thornthwaite from the Kimbal Group. Have a look at the book samples especially Sample package for custom SCD handling. All input columns are passed through the transformation unaltered, those selected are used to generate the checksum which is passed out through a single output column, Checksum. This does not restrict the number of columns available downstream from the transformation, as columns will always flow through a transformation. The Checksum output column is in addition to all existing columns within the pipeline buffer. The Checksum Transformation uses an algorithm based on the .Net framework GetHashCode method, it is not consistent with the T-SQL CHECKSUM() or BINARY_CHECKSUM() functions. The transformation does not support the following Integration Services data types, DT_NTEXT, DT_IMAGE and DT_BYTES. ChecksumAlgorithm Property There ChecksumAlgorithm property is defined with an enumeration. It was first added in v1.3.0, when the FrameworkChecksum was added. All previous algorithms are still supported for backward compatibility as ChecksumAlgorithm.Original (0). Original - Orginal checksum function, with known issues around column separators and null columns. This was deprecated in the first SQL Server 2005 RTM release. FrameworkChecksum - The hash function is based on the .NET Framework GetHash method for object types. This is based on the .NET Object.GetHashCode() method, which unfortunately differs between x86 and x64 systems. For that reason we now default to the CRC32 option. CRC32 - Using a standard 32-bit cyclic redundancy check (CRC), this provides a more open implementation. The component is provided as an MSI file, however to complete the installation, you will have to add the transformation to the Visual Studio toolbox by hand. This process has been described in detail in the related FAQ entry for How do I install a task or transform component?, just select Checksum from the SSIS Data Flow Items list in the Choose Toolbox Items window. Downloads The Checksum Transformation is available for SQL Server 2005, SQL Server 2008 (includes R2) and SQL Server 2012. Please choose the version to match your SQL Server version, or you can install multiple versions and use them side by side if you have more than one version of SQL Server installed. Checksum Transformation for SQL Server 2005 Checksum Transformation for SQL Server 2008 Checksum Transformation for SQL Server 2012 Version History SQL Server 2012 Version 3.0.0.27 – SQL Server 2012 release. Includes upgrade support for both 2005 and 2008 packages to 2012. (5 Jun 2010) SQL Server 2008 Version 2.0.0.27 – Fix for CRC-32 algorithm that inadvertently made it sort dependent. Fix for race condition which sometimes lead to the error Item has already been added. Key in dictionary: '79764919' . Fix for upgrade mappings between 2005 and 2008. (19 Oct 2010) Version 2.0.0.24 - SQL Server 2008 release. Introduces the new CRC-32 algorithm, which is consistent across x86 and x64.. The default algorithm is now CRC32. (29 Oct 2008) Version 2.0.0.6 - SQL Server 2008 pre-release. This version was released by mistake as part of the site migration, and had known issues. (20 Oct 2008) SQL Server 2005 Version 1.5.0.43 – Fix for CRC-32 algorithm that inadvertently made it sort dependent. Fix for race condition which sometimes lead to the error Item has already been added. Key in dictionary: '79764919' . (19 Oct 2010) Version 1.5.0.16 - Introduces the new CRC-32 algorithm, which is consistent across x86 and x64. The default algorithm is now CRC32. (20 Oct 2008) Version 1.4.0.0 - Installer refresh only. (22 Dec 2007) Version 1.4.0.0 - Refresh for minor UI enhancements. (5 Mar 2006) Version 1.3.0.0 - SQL Server 2005 RTM. The checksum algorithm has changed to improve cardinality when calculating multiple column checksums. The original algorithm is still available for backward compatibility. Fixed custom UI bug with Output column name not persisting. (10 Nov 2005) Version 1.2.0.1 - SQL Server 2005 IDW 15 June CTP. A user interface is provided, as well as the ability to change the checksum output column name. (29 Aug 2005) Version 1.0.0 - Public Release (Beta). (30 Oct 2004) Screenshot

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  • SOA, Java EE and data organization

    - by jolasveinn
    At the company I work for, we're currently splitting up our monolith solution into a number of small services (SOA). Many of the services are small, so we'd like to deploy a number of these services on the same application server, JBoss 7.1 in this case. As per the SOA philosophy, the independence of each service and the teams working on them is very important. What would be the best way to organize the data? Use one schema per service Would you use one datasource per schema in the application server? Or use one datasource, prefixing all DB object names with the schema name in some transparent manner? Use a shared schema, but evading any naming collisions by requiring each service to use a distinct prefix for all DB objects Other options? Am I maybe thinking this completely wrong here? :)

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  • Does a mobile app need more access than the public API of a site?

    - by Iain
    I have a site with a public API, and some mobile app developers have been brought in to produce an iPhone app for the site. They insist they need to see the database schema, but as I understand it, they should only need access to the documented public API. Am I right? Is there something I've missed? I've told them that if there's a feature missing or data they require I can extend the API so that they can access it. I thought a web service API held to much the same principles as OOP object API's, in that the implementation details should be hidden as much as possible. I'm not a mobile app developer so if there is something I don't quite see then please let me know. Any insight or help will be much appreciated.

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  • How can I selectively update XNA GameComponents?

    - by Bill
    I have a small 2D game I'm working on in XNA. So far, I have a player-controlled ship that operates on vector thrust and is terribly fun to spin around in circles. I've implemented this as a DrawableGameComponent and registered it with the game using game.Components.Add(this) in the Ship object constructor. How can I implement features like pausing and a menu system with my current implementation? Is it possible to set certain GameComponents to not update? Is this something for which I should even be using a DrawableGameComponent? If not, what are more appropriate uses for this?

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  • Digikam: What's the problem?

    - by Unapiedra
    I installed Digikam by using the Philip5-PPA. When I run it I get the error below. This is by running it through gdb: Starting program: /usr/bin/digikam /usr/bin/digikam: error while loading shared libraries: libcxcore.so.2.1: cannot open shared object file: No such file or directory [Inferior 1 (process 29894) exited with code 0177] What should I do to find the error and fix it? I can see that somehow libcxcore.so.2.1 is wanted but not found. Is this an error of the PPA, or can I simply point it in the right direction? Can I raise an issue with the PPA creator through launchpad? Some next steps would be quite helpful.

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  • XmlWriter and lower ASCII characters

    - by Rick Strahl
    Ran into an interesting problem today on my CodePaste.net site: The main RSS and ATOM feeds on the site were broken because one code snippet on the site contained a lower ASCII character (CHR(3)). I don't think this was done on purpose but it was enough to make the feeds fail. After quite a bit of debugging and throwing in a custom error handler into my actual feed generation code that just spit out the raw error instead of running it through the ASP.NET MVC and my own error pipeline I found the actual error. The lovely base exception and error trace I got looked like this: Error: '', hexadecimal value 0x03, is an invalid character. at System.Xml.XmlUtf8RawTextWriter.InvalidXmlChar(Int32 ch, Byte* pDst, Boolean entitize)at System.Xml.XmlUtf8RawTextWriter.WriteElementTextBlock(Char* pSrc, Char* pSrcEnd)at System.Xml.XmlUtf8RawTextWriter.WriteString(String text)at System.Xml.XmlWellFormedWriter.WriteString(String text)at System.Xml.XmlWriter.WriteElementString(String localName, String ns, String value)at System.ServiceModel.Syndication.Rss20FeedFormatter.WriteItemContents(XmlWriter writer, SyndicationItem item, Uri feedBaseUri)at System.ServiceModel.Syndication.Rss20FeedFormatter.WriteItem(XmlWriter writer, SyndicationItem item, Uri feedBaseUri)at System.ServiceModel.Syndication.Rss20FeedFormatter.WriteItems(XmlWriter writer, IEnumerable`1 items, Uri feedBaseUri)at System.ServiceModel.Syndication.Rss20FeedFormatter.WriteFeed(XmlWriter writer)at System.ServiceModel.Syndication.Rss20FeedFormatter.WriteTo(XmlWriter writer)at CodePasteMvc.Controllers.ApiControllerBase.GetFeed(Object instance) in C:\Projects2010\CodePaste\CodePasteMvc\Controllers\ApiControllerBase.cs:line 131 XML doesn't like extended ASCII Characters It turns out the issue is that XML in general does not deal well with lower ASCII characters. According to the XML spec it looks like any characters below 0x09 are invalid. If you generate an XML document in .NET with an embedded &#x3; entity (as mine did to create the error above), you tend to get an XML document error when displaying it in a viewer. For example, here's what the result of my  feed output looks like with the invalid character embedded inside of Chrome which displays RSS feeds as raw XML by default: Other browsers show similar error messages. The nice thing about Chrome is that you can actually view source and jump down to see the line that causes the error which allowed me to track down the actual message that failed. If you create an XML document that contains a 0x03 character the XML writer fails outright with the error: '', hexadecimal value 0x03, is an invalid character. The good news is that this behavior is overridable so XML output can at least be created by using the XmlSettings object when configuring the XmlWriter instance. In my RSS configuration code this looks something like this:MemoryStream ms = new MemoryStream(); var settings = new XmlWriterSettings() { CheckCharacters = false }; XmlWriter writer = XmlWriter.Create(ms,settings); and voila the feed now generates. Now generally this is probably NOT a good idea, because as mentioned above these characters are illegal and if you view a raw XML document you'll get validation errors. Luckily though most RSS feed readers however don't care and happily accept and display the feed correctly, which is good because it got me over an embarrassing hump until I figured out a better solution. How to handle extended Characters? I was glad to get the feed fixed for the time being, but now I was still stuck with an interesting dilemma. CodePaste.net accepts user input for code snippets and those code snippets can contain just about anything. This means that ASP.NET's standard request filtering cannot be applied to this content. The code content displayed is encoded before display so for the HTML end the CHR(3) input is not really an issue. While invisible characters are hardly useful in user input it's not uncommon that odd characters show up in code snippets. You know the old fat fingering that happens when you're in the middle of a coding session and those invisible characters do end up sometimes in code editors and then end up pasted into the HTML textbox for pasting as a Codepaste.net snippet. The question is how to filter this text? Looking back at the XML Charset Spec it looks like all characters below 0x20 (space) except for 0x09 (tab), 0x0A (LF), 0x0D (CR) are illegal. So applying the following filter with a RegEx should work to remove invalid characters:string code = Regex.Replace(item.Code, @"[\u0000-\u0008,\u000B,\u000C,\u000E-\u001F]", ""); Applying this RegEx to the code snippet (and title) eliminates the problems and the feed renders cleanly.© Rick Strahl, West Wind Technologies, 2005-2012Posted in .NET  XML   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Alternatives to NSMutableArray for storing 2D grid - iOS Cocos2d

    - by SundayMonday
    I'm creating a grid-based iOS game using Cocos2d. Currently the grid is stored in an NSMutableArray that contains other NSMutableArrays (the latter are rows in the grid). This works ok and performance so far is pretty good. However the syntax feels bulky and the indexing isn't very elegant (using CGPoints, would prefer integer indices). I'm looking for an alternative. What are some alternatives data structures for 2D arrays in this situation? In my game it's very common to add and remove rows from the bottom of the grid. So the grid might start off 10x10, grow to 17x10, shrink to 8x10 and then finally end with 2x10. Note the column count is constant. I've consider using a vector<vector<Object*>>. Also I'm vaguely aware of some type of "fast array" or similar offered by Cocos2d. I'd just like to learn about best practices from other developers!

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  • Zune API Library for Ruby

    - by kerry
    Those of you who know me, know my favorite music player is the Zune. For some reason it seems most of my spare time lately seems to be creating Zune API libraries for different languages (I have a PHP one as well).  Here’s another one for Ruby!  If you use it, let me know.  I would love to hear what people are working on. It’s hosted at github, and very easy to use. zune_card = Zune::ZuneCard.for('a_zune_tag') Checkout the README for deets on what fields the object will have.

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  • Event Driven Communication in Game Engine - Yes or No?

    - by Bunkai.Satori
    As I am reading book Game Coding Complete (http://www.amazon.com/Game-Coding-Complete-Third-McShaffry/dp/1584506806/ref=sr_1_1?ie=UTF8&qid=1295978774&sr=8-1), the author recommend Event Driven communication among the all game objects and modules. Basicaly, all the living game actors and object should communicate with the key modules (Physics, AI, Game Logic, Game View, etc..) via internal event messaging system. This would mean designing efficient event manager as well. My question is, whether this is proven and recommended approach. If it is not properly designed, it might mean consuming a lot of CPU cycles, which can be used elsewhere. This is especially true, if the game is targetted for mobile platform. What is your opinion and recommendation, please?

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  • XNA Transparency depending on drawing order?

    - by DarthRoman
    I am drawing two 3D objects, both of them can fade from opaque to transparent independently, and they can intersect between them (so you cannot say when one of them is before the other one). Look at the image for a better understanding (one of the object is a terrain and the other one an area): Now, if I apply transparency to both of them, and draw the terrain before the area, the terrain is not transparent respecting to the area, but the area is: And finally, if I draw the area before the terrain, then the area is not transparent respecting of the terrain: QUESTION: How can I make all the objects transparent to the rest of objects without depending on the drawing order?

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  • jQuery with SharePoint solutions

    - by KunaalKapoor
    For me jQuery is the 'Plan-B' for everything.And most of my projects include the use of jQuery for something or the other, so I decided to write a small note on what works best while using jQuery along with SharePoint.I prefer to use the jQuery JavaScript library, which is far more robust, easier to use, and allows for plugins. Follow the steps below to add jQuery to your master page. For office 365, the prefered location to add jQuery files is the "Site Asserts" library.Deployment Best PracticesThey are only as good as the context it’s being referenced.  In other words, take into account your world before applying it.Script your deployment options.  Folder in SPD. Use the file system.  Make external references.  The JQuery library is on the Microsoft Ajax Content Delivery Network. You may even choose to publish to and from the document library. (pros and cons to this approach)Reference options when referencing the script.ScriptLink will make sure it’s loaded at the top of the page and only loaded once. You need Visual Studio or SPDContent Editor Web Part (CEWP).  Drop it on the page and it’s there.  Easy but dangerousCustom Actions. Great for global deployments of JQuery.  Loads it on every page. It also works in Sandbox installations.Deployment Maintenance Dont’sDon’t add scripts directly to your Master Page. That’s way too much effort because the pages are hard to maintain.Don’t add scripts directly to the CEWP.  Use a content link instead. That will allow for reuse. If you or someone deletes the CEWP you won’t lose code in the web partSecurity.  Any scripts run with the same privileges of the current user.  In other words, you can’t get in trouble.Development Best PracticesDon’t abuse the DOM.  There are better options to load the DOM without hitting it 1,000 times.User other performance boosters.Try other libraries.  Try some custom codeAvoid String conversionMinify your filesUse CAML to reduce number of returns rowsOnly update your JQuery library AFTER RIGOROUS REGRESSION TESTINGCRUD operations can come with some funSP Services wraps SharePoint’s web services for executionThe Bing SDK is pretty easy to use.  You can add it to your page with a script,  put it into a content editor web part and connect it from the address parameters in a list.Steps:1. Go to jquery.com and download the latest jQuery library to your desktop. You want to get the compressed production version, not the development version.2. Open SharePoint Designer (SPD) and connect to the root level of your site's site collection.In SPD, open the "Style Library" folder. Create a folder named "Scripts" inside of the Style Library. Drag the jQuery library JavaScript file from your desktop into the Scripts folder.In the Scripts folder, create a new JavaScript file and name it (e.g. "actions.js").3. If you are using visual studio add a folder for js, you can create a new folder at the root level or if you prefer more cleaner solutions like me, you can use the layouts folder which cleans out on deactivation/uninstall.4. Within the <head> tag of the master page, add a script reference to the jQuery library just above the content place holder named "PlaceHolderAdditonalPageHead" (and above your custom CSS references, if applicable) as follows:<script src="/Style%20Library/Scripts/{jquery library file}.js" type="text/javascript"></script>Immediately after the jQuery library reference add a script reference to your custom scripts file as follows:<script src="/Style%20Library/Scripts/actions.js" type="text/javascript"></script>Inside your script tag, you can test if jQuery is already defined and if not, then add it to the page.<script type='text/javascript'>  if (typeof jQuery == 'undefined')    document.write('<scr'+'ipt type="text/javascript" src="http://code.jquery.com/jquery-1.6.1.min.js"></sc'+'ript>');</script>For the inquisitive few... Read on if you'd like :)Why jQuery on SharePoiny is AwesomeIt’s all about that visual wow factor.  You can get past that, “But it looks like SharePoint”  Take a long list view and put it into JQuery with pagination, etc and you are the hero.  It’s also about new controls you get with JQuery that you couldn’t do before.Why jQuery with SharePoint should be AwfulAlthough it’s fairly easy to get jQuery up and running. Copy/Paste can cause a problem.  If you don’t understand what it’s doing in the Client Object Model and the Document Object Model then it will do things on your site that were completely unexpected. Many blogs will note workarounds they employed on their sites. Why it’s not working: Debugging “sucks”.You need to develop small blocks of functionality, Test it by putting in some alerts  and console.log. Set breakpoints and monitor the DOM via Firebug and some IE development toolsPerformance - It happens all the time. But you should look at the tradeoffs. More time may give you more functionality.Consistency - ”But it works fine on my computer. So test on many browsers.  Take into account client resourcesHarm the Farm -  You need to code wisely and negatively test.  Don’t be the cause of a DoS attack that’s really JQuery asking for a resource over and over and over again.  So code wisely. Do negative testing. Monitor Server Resources.They also did a demo where JQuery did an endless loop to pull data from a list. It’s a poor decision but also an easy mistake.  They spiked their server resources within a couple seconds and had to shut down the call before it brought it down.ConclusionJQuery is now another tool in your tool kit. You don’t have to use it. Use it where it makes sense and where it helps you get your job done.Don’t abuse it, you will pay for it laterIt will add to page bloat so take that into accountIt can slow your performance

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  • Silverlight 4 Twitter Client &ndash; Part 7

    - by Max
    Download this article as a PDF Welcome back :) This week we are going to look at something more exciting and a much required feature for any twitter client – auto refresh so as to show new status updates. We are going to achieve this using Silverlight 4 Timers and a bit and refresh our datagrid every 2 minutes to show new updates. We will do this so that we do only minimal request to the twitter api, so that twitter does not block us – there is a limit of 150 request an hour. Let us get started now. Also we will get the profile user id hyperlinked, so that when ever the user click on it, we will take them to their twitter page. Also it was a pain to always run this application by pressing F5, then it would open in a browser you would have to right click uninstall and install it again to see any changes. All this and yet we were not able to debug it :( Now there is a solution for this to run a silverlight application directly out of browser and yet have the debug feature. Super cool, here is how. Right on the Silverlight project and go to debug and then select the Out-Of-Browser application option and choose the *.Web project. Then just right click on the SL project and set as Startup Project. There you go, now every time you press F5, it will automatically run out of browser and still have the debug options. I go to know about this after some binging. Now let us jump to the core straight away. 1) To get the user id hyperlinked, we need to have a DataGridTemplateColumn and within that have a HyperLinkButton. The code for this will  be <data:DataGridTemplateColumn> <data:DataGridTemplateColumn.CellTemplate> <DataTemplate> <HyperlinkButton Click="HyperlinkButton_Click" Content="{Binding UserName}" TargetName="_blank" ></HyperlinkButton> </DataTemplate> </data:DataGridTemplateColumn.CellTemplate> </data:DataGridTemplateColumn> 2) Now let us look at how we are getting this done by looking into HyperlinkButton_Click event handler. There we will dynamically set the NavigateUri to the twitter page. I tried to do this using some binding, eval like stuff as in ASP.NET, but no luck! private void HyperlinkButton_Click(object sender, RoutedEventArgs e) { HyperlinkButton hb = (HyperlinkButton)e.OriginalSource; hb.NavigateUri = new Uri("http://twitter.com/" + hb.Content.ToString(), UriKind.Absolute); } 3) Now we need to switch on our Timer right in the OnNavigated to event on our SL page. So we need to modify our OnNavigated event to some thing like below: protected override void OnNavigatedTo(NavigationEventArgs e) { image1.Source = new BitmapImage(new Uri(GlobalVariable.profileImage, UriKind.Absolute)); this.Title = GlobalVariable.getUserName() + " - Home"; if (!GlobalVariable.isLoggedin()) this.NavigationService.Navigate(new Uri("/Login", UriKind.Relative)); else { currentGrid = "Timeline-Grid"; TwitterCredentialsSubmit(); myDispatcherTimer.Interval = new TimeSpan(0, 0, 0, 60, 0); myDispatcherTimer.Tick += new EventHandler(Each_Tick); myDispatcherTimer.Start(); } } I use a global string – here it is currentGrid variable to indicate what is bound in the datagrid so that after every timer tick, I can rebind the latest data to it again. Like I will only rebind the friends timeline again if the data grid currently holds it and I’ll only rebind the respective list status again in the data grid, if already a list status is bound to the data grid. In the above timer code, its set to trigger the Each_Tick event handler every 1 minute (60 seconds). TimeSpan takes in (days, hours, minutes, seconds, milliseconds). 4) Now we need to set the list name in the currentGrid variable when a list button is clicked. So add the code line below to the list button event handler currentGrid = currentList = b.Content.ToString(); 5) Now let us see how Each_Tick event handler is implemented. public void Each_Tick(object o, EventArgs sender) { if (!currentGrid.Equals("Timeline-Grid")) getListStatuses(currentGrid); else { WebRequest.RegisterPrefix("https://", System.Net.Browser.WebRequestCreator.ClientHttp); WebClient myService = new WebClient(); myService.AllowReadStreamBuffering = true; myService.UseDefaultCredentials = false; myService.Credentials = new NetworkCredential(GlobalVariable.getUserName(), GlobalVariable.getPassword()); myService.DownloadStringCompleted += new DownloadStringCompletedEventHandler(TimelineRequestCompleted); myService.DownloadStringAsync(new Uri("https://twitter.com/statuses/friends_timeline.xml")); } } If the data grid hold friends timeline, I just use the same bit of code we had already to bind the friends timeline to the data grid. Copy Paste. But if it is some list timeline that is bound in the datagrid, I then call the getListStatus method with the currentGrid string which will actually be holding the list name. 6) I wanted to make the hyperlinks inside the status message as hyperlinks and when the user clicks on it, we can then open that link. I tried using a convertor and using a regex to recognize a url and wrap it up with a href, but that is not gonna work in silverlight textblock :( Anyways that convertor code is in the zip file. 7) You can get the complete project files from here. 8) Please comment below for your doubts, suggestions, improvements. I will try to reply as early as possible. Thanks for all your support. Technorati Tags: Silverlight 4,Datagrid,Twitter API,Silverlight Timer

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  • What is the best HTML specification to be used as of Q1 2011?

    - by Rob McKinnon
    While developing a web application, what is the best spec to use? HTML4.01 HTML5 XHTML trans XHTML1.1 I was taught to use XHTML1.0 strict in uni and to avoid applet/iframe/tables(except in forms). I noticed that some deprecated tags are available in HTML5. Is it safe to code in HTML5? If so should I use target='', and the aforementioned tags? I have noticed that there are many alternatives to choose from including canvas, object. I have no preference, although Iframe tags are being dispensed from sources like Facebook/Google/etc. What would be the best avenue to take for Spec as of now(Feb 2011)?

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  • Why use an OO approach instead of a giant "switch" statement?

    - by James P. Wright
    I am working in a .Net, C# shop and I have a coworker that keeps insisting that we should use giant Switch statements in our code with lots of "Cases" rather than more object oriented approaches. His argument consistently goes back to the fact that a Switch statement compiles to a "cpu jump table" and is therefore the fastest option (even though in other things our team is told that we don't care about speed). I honestly don't have an argument against this...because I don't know what the heck he's talking about. Is he right? Is he just talking out his ass? Just trying to learn here.

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  • Question about component based design: handling objects interaction

    - by Milo
    I'm not sure how exactly objects do things to other objects in a component based design. Say I have an Obj class. I do: Obj obj; obj.add(new Position()); obj.add(new Physics()); How could I then have another object not only move the ball but have those physics applied. I'm not looking for implementation details but rather abstractly how objects communicate. In an entity based design, you might just have: obj1.emitForceOn(obj2,5.0,0.0,0.0); Any article or explanation to get a better grasp on a component driven design and how to do basic things would be really helpful.

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  • Should I be worried if I solve a lot of my problems the same way?

    - by Bryan Harrington
    I really enjoy programming games and puzzle creators/games. I find myself engineering a lot of these problems the same way and ultimately using similar technique to program them that I'm really comfortable with. To give you brief insight, I like to create graphs where nodes are represented with objects. These object hold data such as coordinates, positions and of course references to other neighboring objects. I'll place them all in a data structure and make decisions on this information in a "game loop". While this is a brief example, its not exact in all situations. It's just one way I feel really comfortable with. Is this bad?

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  • Node Serialization in NetBeans Platform 7.0

    - by Geertjan
    Node serialization makes sense when you're not interested in the data (since that should be serialized to a database), but in the state of the application. For example, when the application restarts, you want the last selected node to automatically be selected again. That's not the kind of information you'll want to store in a database, hence node serialization is not about data serialization but about application state serialization. I've written about this topic in October 2008, here and here, but want to show how to do this again, using NetBeans Platform 7.0. Somewhere I remember reading that this can't be done anymore and that's typically the best motivation for me, i.e., to prove that it can be done after all. Anyway, in a standard POJO/Node/BeanTreeView scenario, do the following: Remove the "@ConvertAsProperties" annotation at the top of the class, which you'll find there if you used the Window Component wizard. We're not going to use property-file based serialization, but plain old java.io.Serializable  instead. In the TopComponent, assuming it is named "UserExplorerTopComponent", typically at the end of the file, add the following: @Override public Object writeReplace() { //We want to work with one selected item only //and thanks to BeanTreeView.setSelectionMode, //only one node can be selected anyway: Handle handle = NodeOp.toHandles(em.getSelectedNodes())[0]; return new ResolvableHelper(handle); } public final static class ResolvableHelper implements Serializable { private static final long serialVersionUID = 1L; public Handle selectedHandle; private ResolvableHelper(Handle selectedHandle) { this.selectedHandle = selectedHandle; } public Object readResolve() { WindowManager.getDefault().invokeWhenUIReady(new Runnable() { @Override public void run() { try { //Get the TopComponent: UserExplorerTopComponent tc = (UserExplorerTopComponent) WindowManager.getDefault().findTopComponent("UserExplorerTopComponent"); //Get the display text to search for: String selectedDisplayName = selectedHandle.getNode().getDisplayName(); //Get the root, which is the parent of the node we want: Node root = tc.getExplorerManager().getRootContext(); //Find the node, by passing in the root with the display text: Node selectedNode = NodeOp.findPath(root, new String[]{selectedDisplayName}); //Set the explorer manager's selected node: tc.getExplorerManager().setSelectedNodes(new Node[]{selectedNode}); } catch (PropertyVetoException ex) { Exceptions.printStackTrace(ex); } catch (IOException ex) { Exceptions.printStackTrace(ex); } } }); return null; } } Assuming you have a node named "UserNode" for a type named "User" containing a property named "type", add the bits in bold below to your "UserNode": public class UserNode extends AbstractNode implements Serializable { static final long serialVersionUID = 1L; public UserNode(User key) { super(Children.LEAF); setName(key.getType()); } @Override public Handle getHandle() { return new CustomHandle(this, getName()); } public class CustomHandle implements Node.Handle { static final long serialVersionUID = 1L; private AbstractNode node = null; private final String searchString; public CustomHandle(AbstractNode node, String searchString) { this.node = node; this.searchString = searchString; } @Override public Node getNode() { node.setName(searchString); return node; } } } Run the application and select one of the user nodes. Close the application. Start it up again. The user node is not automatically selected, in fact, the window does not open, and you will see this in the output: Caused: java.io.InvalidClassException: org.serialization.sample.UserNode; no valid constructor Read this article and then you'll understand the need for this class: public class BaseNode extends AbstractNode { public BaseNode() { super(Children.LEAF); } public BaseNode(Children kids) { super(kids); } public BaseNode(Children kids, Lookup lkp) { super(kids, lkp); } } Now, instead of extending AbstractNode in your UserNode, extend BaseNode. Then the first non-serializable superclass of the UserNode has an explicitly declared no-args constructor, Do the same as the above for each node in the hierarchy that needs to be serialized. If you have multiple nodes needing serialization, you can share the "CustomHandle" inner class above between all the other nodes, while all the other nodes will also need to extend BaseNode (or provide their own non-serializable super class that explicitly declares a no-args constructor). Now, when I run the application, I select a node, then I close the application, restart it, and the previously selected node is automatically selected when the application has restarted.

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  • Session and Cache are By Reference

    Recently a colleague remarked that if he got a List of some type out of the ASP.NET Cache, and changed an item, the Cache item would also change.That is correct. Session (InProc) , Cache and Application all return "live" references. A good writeup on this can be found by friend and fellow MVP Rick Strahl here:http://www.west-wind.com/Weblog/posts/1214.aspxIf you do not want this behavior, you need to either delete the Session / Cache / Application object and replace it with what you want later, or...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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  • Open source projects, how to choose?!

    - by Dhaivat Pandya
    I would like to join an open source project since I think I am good enough at programming to progress onto reading others code and to modify it. But the proble mis, how would I choose an open source project to work on? I know many languages and chief ones that I am good are python, C++ (not really very good at C, the lack of object orientation is difficult for me) and Java. For c++, I am proficient wit Qt. I would like to start with something that isn't huge, and hasn't reached a phase where the bugs are so complicated it would take me a month to understand what affects the bug. Any suggestions? At the current time, I don't use any libraries in either of the mentioned libraries that I would need to modify (AFAIK).

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  • How does a BSP tree work for Z sorting?

    - by Jenko
    I'm developing a 3D engine in software, and so I must compute Z sorting manually. I'm currently using the painters algorithm to sort triangles and then drawing them back-to-front. This causes artifacts that I'm trying to correct. Would using a dynamic BSP-tree ensure "correct Z sorting" of triangles? Why? Because the bounding volumes of triangles would be similar? Since I would have a single "world" BSP tree, would I have to remove and re-add any moved/scaled/rotated object into the tree? Is it possible to add triangles into a BSP tree without the expensive cutting process? Why do you need to cut triangles on the axis planes anyway? Is it faster to traverse a BSP tree from any angle, than to sort all tris each draw like the painters algorithm?

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  • Cannot install ia32-libs on a 64 bit Ubuntu installation

    - by Swarnendu Biswas
    I am using a 64-bit installation of Oneiric. I need to install the ia32-libs package to get some applications (evince, adobe reader) to work. For example, adobe reader is giving the following error: error while loading shared libraries: libGL.so.1: cannot open shared object file: No such file or directory. However, I am not able to install it since it is showing a dependency on ia32-libs-multiarch, which in turn is showing a dependency on gstreamer0.10-plugins-good:i386. This in turn depends on few other packages. How can I install these packages safely and still meet all the dependencies.

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  • Why do we use Pythagoras in game physics?

    - by Starkers
    I've recently learned that we use Pythagoras a lot in our physics calculations and I'm afraid I don't really get the point. Here's an example from a book to make sure an object doesn't travel faster than a MAXIMUM_VELOCITY constant in the horizontal plane: MAXIMUM_VELOCITY = <any number>; SQUARED_MAXIMUM_VELOCITY = MAXIMUM_VELOCITY * MAXIMUM_VELOCITY; function animate(){ var squared_horizontal_velocity = (x_velocity * x_velocity) + (z_velocity * z_velocity); if( squared_horizontal_velocity <= SQUARED_MAXIMUM_VELOCITY ){ scalar = squared_horizontal_velocity / SQUARED_MAXIMUM_VELOCITY; x_velocity = x_velocity / scalar; z_velocity = x_velocity / scalar; } } Let's try this with some numbers: An object is attempting to move 5 units in x and 5 units in z. It should only be able to move 5 units horizontally in total! MAXIMUM_VELOCITY = 5; SQUARED_MAXIMUM_VELOCITY = 5 * 5; SQUARED_MAXIMUM_VELOCITY = 25; function animate(){ var x_velocity = 5; var z_velocity = 5; var squared_horizontal_velocity = (x_velocity * x_velocity) + (z_velocity * z_velocity); var squared_horizontal_velocity = 5 * 5 + 5 * 5; var squared_horizontal_velocity = 25 + 25; var squared_horizontal_velocity = 50; // if( squared_horizontal_velocity <= SQUARED_MAXIMUM_VELOCITY ){ if( 50 <= 25 ){ scalar = squared_horizontal_velocity / SQUARED_MAXIMUM_VELOCITY; scalar = 50 / 25; scalar = 2.0; x_velocity = x_velocity / scalar; x_velocity = 5 / 2.0; x_velocity = 2.5; z_velocity = z_velocity / scalar; z_velocity = 5 / 2.0; z_velocity = 2.5; // new_horizontal_velocity = x_velocity + z_velocity // new_horizontal_velocity = 2.5 + 2.5 // new_horizontal_velocity = 5 } } Now this works well, but we can do the same thing without Pythagoras: MAXIMUM_VELOCITY = 5; function animate(){ var x_velocity = 5; var z_velocity = 5; var horizontal_velocity = x_velocity + z_velocity; var horizontal_velocity = 5 + 5; var horizontal_velocity = 10; // if( horizontal_velocity >= MAXIMUM_VELOCITY ){ if( 10 >= 5 ){ scalar = horizontal_velocity / MAXIMUM_VELOCITY; scalar = 10 / 5; scalar = 2.0; x_velocity = x_velocity / scalar; x_velocity = 5 / 2.0; x_velocity = 2.5; z_velocity = z_velocity / scalar; z_velocity = 5 / 2.0; z_velocity = 2.5; // new_horizontal_velocity = x_velocity + z_velocity // new_horizontal_velocity = 2.5 + 2.5 // new_horizontal_velocity = 5 } } Benefits of doing it without Pythagoras: Less lines Within those lines, it's easier to read what's going on ...and it takes less time to compute, as there are less multiplications Seems to me like computers and humans get a better deal without Pythagoras! However, I'm sure I'm wrong as I've seen Pythagoras' theorem in a number of reputable places, so I'd like someone to explain me the benefit of using Pythagoras to a maths newbie. Does this have anything to do with unit vectors? To me a unit vector is when we normalize a vector and turn it into a fraction. We do this by dividing the vector by a larger constant. I'm not sure what constant it is. The total size of the graph? Anyway, because it's a fraction, I take it, a unit vector is basically a graph that can fit inside a 3D grid with the x-axis running from -1 to 1, z-axis running from -1 to 1, and the y-axis running from -1 to 1. That's literally everything I know about unit vectors... not much :P And I fail to see their usefulness. Also, we're not really creating a unit vector in the above examples. Should I be determining the scalar like this: // a mathematical work-around of my own invention. There may be a cleverer way to do this! I've also made up my own terms such as 'divisive_scalar' so don't bother googling var divisive_scalar = (squared_horizontal_velocity / SQUARED_MAXIMUM_VELOCITY); var divisive_scalar = ( 50 / 25 ); var divisive_scalar = 2; var multiplicative_scalar = (divisive_scalar / (2*divisive_scalar)); var multiplicative_scalar = (2 / (2*2)); var multiplicative_scalar = (2 / 4); var multiplicative_scalar = 0.5; x_velocity = x_velocity * multiplicative_scalar x_velocity = 5 * 0.5 x_velocity = 2.5 Again, I can't see why this is better, but it's more "unit-vector-y" because the multiplicative_scalar is a unit_vector? As you can see, I use words such as "unit-vector-y" so I'm really not a maths whiz! Also aware that unit vectors might have nothing to do with Pythagoras so ignore all of this if I'm barking up the wrong tree. I'm a very visual person (3D modeller and concept artist by trade!) and I find diagrams and graphs really, really helpful so as many as humanely possible please!

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  • ASP.NET C# - do you need a separate datasource for each gridview? [closed]

    - by Brian McCarthy
    Do you need a separate datasource for each gridview if each gridview is accessing the same database but different tables in the database? I'm getting an error on AppSettings that says non-invocable member. What is the problem with it? Here's the c# code-behind: protected void Search_Zip_Plan_Age_Button_Click(object sender, EventArgs e) { var _with1 = this.ZipPlan_SqlDataSource; _with1.SelectParameters.Clear(); _with1.ConnectionString = System.Configuration.ConfigurationManager.AppSettings("PriceFinderConnectionString").ToString; _with1.SelectCommand = "ssp_get_zipcode_plan"; _with1.SelectParameters.Add("ZipCode", this.ZipCode.Text); _with1.SelectParameters.Add("PlanCode", this.PlanCode.Text); _with1.SelectParameters.Add("Age", this.Age.Text); _with1.SelectCommandType = SqlDataSourceCommandType.StoredProcedure; _with1.CancelSelectOnNullParameter = false; Search_Results_GridView.DataBind(); } thanks!

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  • Multiple Vertex Buffers per Mesh

    - by Daniel
    I've run into the situation where the size of my mesh with all its vertices and indices, is larger than the (optimal) vertex buffer object upper limit (~8MB). I was wondering if I can sub-divide the mesh across multiple vertex buffers, and somehow retain validity of the indices. Ie a triangle with a indice at the first vertex, and an indice at the last (ie in seperate VBOs). All the while maintaining this within Vertex Array Objects. My thoughts are, save myself the hassle, and for meshes (messes :P) such as this, just use the necessary size ( 8MB); which is what I do at the moment. But ideally my buffer manager (wip) at the moment is using optimal sizes; I may just have to make a special case then... Any ideas? If necessary, a simple C++ code example is appreciated. Note: I have also cross-posted this on stackoverflow, as I was not sure as to which it would be more suitable (its partly a design question).

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  • Logic in Entity Components Systems

    - by aaron
    I'm making a game that uses an Entity/Component architecture basically a port of Artemis's framework to c++,the problem arises when I try to make a PlayerControllerComponent, my original idea was this. class PlayerControllerComponent: Component { public: virtual void update() = 0; }; class FpsPlayerControllerComponent: PlayerControllerComponent { public: void update() { //handle input } }; and have a system that updates PlayerControllerComponents, but I found out that the artemis framework does not look at sub-classes the way I thought it would. So all in all my question here is should I make the framework aware of subclasses or should I add a new Component like object that is used for logic.

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