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  • Reading ResultSet from multiple threads

    - by superdario
    Hello, In the database, I have a definition table that is read from the application once upon starting. This definition table rarely changes, so it makes sense to read it once and restart the application every time it changes. However, after the table is read (put into a ResultSet), it will be read by multiple handlers running in their own threads. How do you suggest to accomplish this? My idea was to populate a CachedRowSet, and then create a copy of this set (through the createCopy() method) for each handler every time a new request comes. Do you think this is wise? Does this offer a good performance? Thanks.

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  • WPF binding to a boolean on a control

    - by Jose
    I'm wondering if someone has a simple succinct solution to binding to a dependency property that needs to be the converse of the property. Here's an example I have a textbox that is disabled based on a property in the datacontext e.g.: <TextBox IsEnabled={Binding CanEdit} Text={Binding MyText}/> The requirement changes and I want to make it ReadOnly instead of disabled, so without changing my ViewModel I could do this: In the UserControl resources: <UserControl.Resources> <m:NotConverter x:Key="NotConverter"/> </UserControl.Resources> And then change the TextBox to: <TextBox IsReadOnly={Binding CanEdit,Converter={StaticResource NotConverter}} Text={Binding MyText}/> Which I personally think is EXTREMELY verbose I would love to be able to just do this(notice the !): <TextBox IsReadOnly={Binding !CanEdit} Text={Binding MyText}/> But alas, that is not an option that I know of. I can think of two options. Create an attached property IsNotReadOnly to FrameworkElement(?) and bind to that property If I change my ViewModel then I could add a property CanEdit and another CannotEdit which I would be kind of embarrassed of because I believe it adds an irrelevant property to a class, which I don't think is a good practice. The main reason for the question is that in my project the above isn't just for one control, so trying to keep my project as DRY as possible and readable I am throwing this out to anyone feeling my pain and has come up with a solution :)

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  • De-normalization for the sake of reports - Good or Bad?

    - by Travis
    What are the pros/cons of de-normalizing an enterprise application database because it will make writing reports easier? Pro - designing reports in SSRS will probably be "easier" since no joins will be necessary. Con - developing/maintaining the app to handle de-normalized data will become more difficult due to duplication of data and synchronization. Others?

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  • Using switch and enumerations as substitute for named methods

    - by MatthewMartin
    This pattern pops up a lot. It looks like a very verbose way to move what would otherwise be separate named methods into a single method and then distinguished by a parameter. Is there any good reason to have this pattern over just having two methods Method1() and Method2() ? The real kicker is that this pattern tends to be invoked only with constants at runtime-- i.e. the arguments are all known before compiling is done. public enum Commands { Method1, Method2 } public void ClientCode() { //Always invoked with constants! Never user input. RunCommands(Commands.Method1); RunCommands(Commands.Method2); } public void RunCommands(Commands currentCommand) { switch (currentCommand) { case Commands.Method1: // Stuff happens break; case Commands.Method2: // Other stuff happens break; default: throw new ArgumentOutOfRangeException("currentCommand"); } }

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  • standard debugging way for javascript/jquery

    - by ZX12R
    This is my usual way to debug javascript. Include alert(0); to break the flow and find out what is happening. sometimes when i need multiple check points i do alert('the flow is now in function 1'); alert('the flow is now in function 2'); or sometimes just alert('success'); i would like to know if there is any standard way for debugging adopted as i am finding my current method very intrusive. thanks in advance..:)

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  • Is there a pattern for this?

    - by Timmy
    i have something that requires a matrix of values, similar to pokemon: i have a class object for each of the types, is there a pattern or a good way to implement this, as a middle layer or in the classes?

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  • How to determine which inheriting class is using an abstract class's methods.

    - by Kin
    In my console application have an abstract Factory class "Listener" which contains code for listening and accepting connections, and spawning client classes. This class is inherited by two more classes (WorldListener, and MasterListener) that contain more protocol specific overrides and functions. I also have a helper class (ConsoleWrapper) which encapsulates and extends System.Console, containing methods for writing to console info on what is happening to instances of the WorldListener and MasterListener. I need a way to determine in the abstract ListenerClass which Inheriting class is calling its methods. Any help with this problem would be greatly appreciated! I am stumped :X Simplified example of what I am trying to do. abstract class Listener { public void DoSomething() { if(inheriting class == WorldListener) ConsoleWrapper.WorldWrite("Did something!"); if(inheriting class == MasterListener) ConsoleWrapper.MasterWrite("Did something!"); } } public static ConsoleWrapper { public void WorldWrite(string input) { System.Console.WriteLine("[World] {0}", input); } } public class WorldListener : Listener { public void DoSomethingSpecific() { ConsoleWrapper.WorldWrite("I did something specific!"); } } public void Main() { new WorldListener(); new MasterListener(); } Expected output [World] Did something! [World] I did something specific! [Master] Did something! [World] I did something specific!

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  • Converting ASP.NET MVC to n-Tiered Architecture

    - by Jeff
    I just built an application using ASP.NET MVC. The programmers at my company want to build all future modules using n-Tiered (Presentation Layer, Business Logic Layer, Data Access Layer) architecture. I am not the programmer and need to know why this makes sense? Do I have to completely rewrite the entire code or can it be converted? We are building an HRIS system with Business Intelligence. Somebody please explain why or why not this approach does or does not make sense.

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  • Is there anything bad in declaring static inner class inside interface in java?

    - by Roman
    I have an interface ProductService with method findByCriteria. This method had a long list of nullable parameters, like productName, maxCost, minCost, producer and so on. I refactored this method by introducing Parameter Object. I created class SearchCriteria and now method signature looks like this: findByCriteria (SearchCriteria criteria) I thought that instances of SearchCriteria are only created by method callers and are only used inside findByCriteria method, i.e.: void processRequest() { SearchCriteria criteria = new SearchCriteria () .withMaxCost (maxCost) ....... .withProducer (producer); List<Product> products = productService.findByCriteria (criteria); .... } and List<Product> findByCriteria(SearchCriteria criteria) { return doSmthAndReturnResult(criteria.getMaxCost(), criteria.getProducer()); } So I did not want to create separate public class for SearchCriteria and put it inside ProductServiceInterface: public interface ProductService { List<Product> findByCriteria (SearchCriteria criteria); static class SearchCriteria { ... } } Is there anything bad in this interface? Where whould you place SearchCriteria class?

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  • Are there any downsides in using C++ for network daemons?

    - by badcat
    Hey guys! I've been writing a number of network daemons in different languages over the past years, and now I'm about to start a new project which requires a new custom implementation of a properitary network protocol. The said protocol is pretty simple - some basic JSON formatted messages which are transmitted in some basic frame wrapping to have clients know that a message arrived completely and is ready to be parsed. The daemon will need to handle a number of connections (about 200 at the same time) and do some management of them and pass messages along, like in a chat room. In the past I've been using mostly C++ to write my daemons. Often with the Qt4 framework (the network parts, not the GUI parts!), because that's what I also used for the rest of the projects and it was simple to do and very portable. This usually worked just fine, and I didn't have much trouble. Being a Linux administrator for a good while now, I noticed that most of the network daemons in the wild are written in plain C (of course some are written in other languages, too, but I get the feeling that 80% of the daemons are written in plain C). Now I wonder why that is. Is this due to a pure historic UNIX background (like KISS) or for plain portability or reduction of bloat? What are the reasons to not use C++ or any "higher level" languages for things like daemons? Thanks in advance! Update 1: For me using C++ usually is more convenient because of the fact that I have objects which have getter and setter methods and such. Plain C's "context" objects can be a real pain at some point - especially when you are used to object oriented programming. Yes, I'm aware that C++ is a superset of C, and that C code is basically C++. But that's not the point. ;)

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  • [MySQL] Efficiently store last X records per item

    - by Saif Bechan
    I want to store the last X records in an MySQL database in an efficient way. So when the 4th record is stored the first should be deleted. The way I do this not is first run a query getting the items. Than check what I should do then insert/delete. There has to be a better way to do this. Any suggestions? Edit I think I should add that the records stored do not have a unique number. They have a mixed par. For example article_id and user_id. Then I want to make a table with the last X items for user_x. Just selecting the article from the table grouped by user and sorted by time is not an option for me. The table where I do the sort and group on has millions of records and gets hit a lot for no reason. So making a table in between with the last X records is way more effient. PS. I am not using this for articles and users.

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  • Projects with browsable source using dependency injection w/ guice?

    - by André
    I often read about dependency injection and I did research on google and I understand in theory what it can do and how it works, but I'd like to see an actual code base using it (Java/guice would be preferred). Can anyone point me to an open source project, where I can see, how it's really used? I think browsing the code and seeing the whole setup shows me more than the ususal snippets in the introduction articles you find around the web. Thanks in advance!

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  • Routing redirection decision

    - by programming late night
    I have really no idea why I'm asking this as this a really completely irrelevant question for which I should have figured out an answer within milliseconds, yet I'm doing it. So in my project I have a Router class which splits up the request and selects the right page to be loaded. Fine so far. Now I have a page displayed when the user requests a page that doesn't exist, you know, 404. So theoretically, if the user entered mydomain.com/404 (I use mod_rewrite with a requests collector via index.php?req=*) the 404 error would be shown to him, but in fact there was no error - the 404 page would be displayed as a perfectly normal page. So if someone would try out requesting the 404 page via /404, he would be shown the page but he can't tell if the 404 page he requested doesn't exist and he is actually getting a, you guessed it, 404 error or if he actually found some flaw in the system that makes him able to see an error page when there is no error. I don't know how dumb this whole thing here is but I'm sure some of you have in fact ran into this problem already. Short version: If the user enters mydomain.com/404 the 404 page is shown even though there is no 404 error. I know this is a completely irrelevant question, please don't tell me, but I just spontaneously wanted to hear your thoughts on it. Strange eh? Should I redirect direct access to my 404-page to the home page? Should I do nothing? Should I just go to bed and stop asking irrelevant stuff?

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  • Java: Make a method abstract for each extending class

    - by Martijn Courteaux
    Hi, Is there any keyword or design pattern for doing this? public abstract class Root { public abstract void foo(); } public abstract class SubClass extends Root { public void foo() { // Do something } } public class SubberClass extends SubClass { // Here is it not necessary to override foo() // So is there a way to make this necessary? // A way to obligate the developer make again the override } Thanks

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  • Unit Testing User Interface. What is an effective way ?

    - by pierocampanelli
    I have an accounting & payroll client/server application where there are several input form with complex data validation rules. I am finding an effective way to perform unit testing of user interface. For complex validation rules I mean: "Disable button X if I Insert a value in textfield Y" "Enable a combobox if I insert a value in a textfield" ...... ...... Most promising pattern i have found is suggested by M. Fowler (http://martinfowler.com/eaaDev/ModelViewPresenter.html). Have you any experience about Unit Testing of User Interface? As technology stack I am using: .NET 3.5 & Windows Forms Widget Library.

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  • Best Practice: Software Versioning

    - by Sebi
    I couldn't find a similar question here on SO, but if you find one please link. Is there any guideline or standard best practice how to version a software you develop in your spare time for fun, but nevertheless will be used by some people? I think it's necessary to version such software so that you know about with version one is talking about (e.g. for bug fixing, support, and so on). But where do I start the versioning? 0.0.0? or 0.0? And then how to I increment the numbers? major release.minor change? and should'nt any commit to a version control system be another version? or is this only for versions which are used in a productive manner?

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  • What is the procedure for debugging a production-only error?

    - by Lord Torgamus
    Let me say upfront that I'm so ignorant on this topic that I don't even know whether this question has objective answers or not. If it ends up being "not," I'll delete or vote to close the post. Here's the scenario: I just wrote a little web service. It works on my machine. It works on my team lead's machine. It works, as far as I can tell, on every machine except for the production server. The exception that the production server spits out upon failure originates from a third-party JAR file, and is skimpy on information. I search the web for hours, but don't come up with anything useful. So what's the procedure for tracking down an issue that occurs only on production machines? Is there a standard methodology, or perhaps category/family of tools, for this? The error that inspired this question has already been fixed, but that was due more to good fortune than a solid approach to debugging. I'm asking this question for future reference. Some related questions: Test accounts and products in a production system Running test on Production Code/Server

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  • What is the recommended way of parsing an XML feed with multiple namespaces with ActionScript 3.0?

    - by dafko
    I have seen the following methods to be used in several online examples, but haven't found any documentation on the recommended way of parsing an XML feed. Method 1: protected function xmlResponseHandler(event:ResultEvent):void { var atom:Namespace = new Namespace("http://www.w3.org/2005/Atom"); var microsoftData:Namespace = new Namespace("http://schemas.microsoft.com/ado/2007/08/dataservices"); var microsoftMetadata:Namespace = new Namespace("http://schemas.microsoft.com/ado/2007/08/dataservices/metadata"); var ac:ArrayCollection = new ArrayCollection(); var keyValuePairs:KeyValuePair; var propertyList:XMLList = (event.result as XML)..atom::entry.atom::content.microsoftMetadata::properties; for each (var properties:XML in propertyList) { keyValuePairs = new KeyValuePair(properties.microsoftData::FieldLocation, properties.microsoftData::Locationid); ac.addItem(keyValuePairs); } cb.dataProvider = ac; } Method 2: protected function xmlResponseHandler(event:ResultEvent):void { namespace atom = "http://www.w3.org/2005/Atom"; namespace d = "http://schemas.microsoft.com/ado/2007/08/dataservices"; namespace m = "http://schemas.microsoft.com/ado/2007/08/dataservices/metadata"; use namespace d; use namespace m; use namespace atom; var ac:ArrayCollection = new ArrayCollection(); var keyValuePairs:KeyValuePair; var propertyList:XMLList = (event.result as XML)..entry.content.properties; for each (var properties:XML in propertyList) { keyValuePairs = new KeyValuePair(properties.FieldLocation, properties.Locationid); ac.addItem(keyValuePairs); } cb.dataProvider = ac; } Sample XML feed: <?xml version="1.0" encoding="iso-8859-1" standalone="yes"?> <feed xml:base="http://www.test.com/Test/my.svc/" xmlns:d="http://schemas.microsoft.com/ado/2007/08/dataservices" xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata" xmlns="http://www.w3.org/2005/Atom"> <title type="text">Test_Locations</title> <id>http://www.test.com/test/my.svc/Test_Locations</id> <updated>2010-04-27T20:41:23Z</updated> <link rel="self" title="Test_Locations" href="Test_Locations" /> <entry> <id>1</id> <title type="text"></title> <updated>2010-04-27T20:41:23Z</updated> <author> <name /> </author> <link rel="edit" title="Test_Locations" href="http://www.test.com/id=1" /> <category term="MySQLModel.Test_Locations" scheme="http://schemas.microsoft.com/ado/2007/08/dataservices/scheme" /> <content type="application/xml"> <m:properties> <d:FieldLocation>Test Location</d:FieldLocation> <d:Locationid>test0129</d:Locationid> </m:properties> </content> </entry> <entry> <id>2</id> <title type="text"></title> <updated>2010-04-27T20:41:23Z</updated> <author> <name /> </author> <link rel="edit" title="Test_Locations" href="http://www.test.com/id=2" /> <category term="MySQLModel.Test_Locations" scheme="http://schemas.microsoft.com/ado/2007/08/dataservices/scheme" /> <content type="application/xml"> <m:properties> <d:FieldLocation>Yet Another Test Location</d:FieldLocation> <d:Locationid>test25</d:Locationid> </m:properties> </content> </entry> </feed>

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  • HTTP headers: Last-Modified - how can it mimimize server load?

    - by gotts
    Imagine the following use case: I use an AJAX request for getting some info about Item and use this URL: http://domain/items/show/1 In my database all items have a field called modified_at where we store the moment when this item was previously modified. How can Last-Modified server HTTP header in response can minimize load/reduce requests/increase responsiveness if we need to process this request every time on the server side? It looks like we don't reduce the number of HTTP requests with that response and we don't reduce the load on server. Who needs this anyway?

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  • Is code clearness killing application performance?

    - by Jorge Córdoba
    As today's code is getting more complex by the minute, code needs to be designed to be maintainable - meaning easy to read, and easy to understand. That being said, I can't help but remember the programs that ran a couple of years ago such as Winamp or some games in which you needed a high performance program because your 486 100 Mhz wouldn't play mp3s with that beautiful mp3 player which consumed all of your CPU cycles. Now I run Media Player (or whatever), start playing an mp3 and it eats up a 25-30% of one of my four cores. Come on!! If a 486 can do it, how can the playback take up so much processor to do the same? I'm a developer myself, and I always used to advise: keep your code simple, don't prematurely optimize for performance. It seems that we've gone from "trying to get it to use the least amount of CPU as possible" to "if it doesn't take too much CPU is all right". So, do you think we are killing performance by ignoring optimizations?

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