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• crontab environment

  - by Adamski

  I have written various scripts to launch Java server applications, which are typically run for 24 hours before being shut down (by invoking the same script with a different parameter). The script relies on environment variables defined in a file: ~/<user>.env, which I source from .bashrc. This works fine when invoking the script from the command line but if I want to add the script as a crontab entry I run into the problem where .bashrc isn't read. My question: What is the best practice approach for solving this problem? I realise I could define a crontab entry such as: * * * * 1-5 /usr/bin/bash -c '. /home/myuser/myuser.env && /home/myuser/scripts/myscript.sh' ... but this seems plain ugly. Alternatively I could source myuser.env at the beginning of every script, but this would become a nightmare to maintain. Any help appreciated.

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• ASP.NET "Object reference not set..." error

  - by Roman

  Hi, I have a website written using ASP.NET. We have a development machine and a deployment server. The site works great on the development machine, but when is transfered (using simple FTP Upload) generates strange behavior. It starts working just fine, but after a while stops working and throws an exception "Exception: Object reference not set to an instance of an object.". The deal is that the absolute path of the website on the development machine is different than on the deployment server (and why should they be similar?) and the exact error is: Exception: Object reference not set to an instance of an object. at SOMEPROJECT_Objects.Player..ctor(Int32 PlayerID) in C:\inetpub\wwwroot\SOMEPROJECTSolution\ALLPROJECT\SOMEPROJECT_Objects\Player.cs:line 123 at SOMEPROJECT_GameLayer.M_Game.PlayerActiveGame(Int32 PlayerID) in C:\inetpub\wwwroot\SOMEPROJECTSolution\ALLPROJECT\SOMEPROJECT_GameLayer\M_Game.cs:line 85 at Web.getsms.Page_Load(Object sender, EventArgs e) in C:\inetpub\wwwroot\SOMEPROJECTSolution\ALLPROJECT\SOMEPROJECT-sms\Web\getsms.aspx.cs:line 59 The address that it is looking for is the address on the DEVELOPMENT machine, where as the site now resides on the deployment server. Any ideas why this happens would be appreciated. Thanks, Roman

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• Migration solution for singletons in an OSGI environment

  - by Ido

  I'm working in a JEE Environment in which each application is in a war file of its own. In the WEB-INF/lib of each application war file there is a common jar that is shared by all applications. This common jar contains several Singletons which are accessed from many points in the code. Because of the war-file boundaries each application has its own instances of the Singletons. Which is how we operate today, since we want to configure some of the singletons differently in each application. Now we are moving towards an OSGi environment, where this solution will no longer work since each bundle has its own class loader, so if I try to access MySingleton which resides in bundle "common.jar" from bundle "appA.jar" or from bundle "appB.jar" I will get the same instance. Remember I "want" a different instance of a singleton per bundle. (as ironic as it sounds) Now I realize the ideal solution would be to fix the code to not rely on those singletons, however due to a tight schedule I was wondering if you guys can suggest some sort of a migration solution that would allow me to use bundle-wide singletons so each of them could be configured per bundle.

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• Is it normal for C++ static initialization to appear twice in the same backtrace?

  - by Joseph Garvin

  I'm trying to debug a C++ program compiled with GCC that freezes at startup. GCC mutex protects function's static local variables, and it appears that waiting to acquire such a lock is why it freezes. How this happens is rather confusing. First module A's static initialization occurs (there are __static_init functions GCC invokes that are visible in the backtrace), which calls a function Foo(), that has a static local variable. The static local variable is an object who's constructor calls through several layers of functions, then suddenly the backtrace has a few ??'s, and then it's is in the static initialization of a second module B (the __static functions occur all over again), which then calls Foo(), but since Foo() never returned the first time the mutex on the local static variable is still set, and it locks. How can one static init trigger another? My first theory was shared libraries -- that module A would be calling some function in module B that would cause module B to load, thus triggering B's static init, but that doesn't appear to be the case. Module A doesn't use module B at all. So I have a second (and horrifying) guess. Say that: Module A uses some templated function or a function in a templated class, e.g. foo<int>::bar() Module B also uses foo<int>::bar() Module A doesn't depend on module B at all At link time, the linker has two instances of foo<int>::bar(), but this is OK because template functions are marked as weak symbols... At runtime, module A calls foo<int>::bar, and the static init of module B is triggered, even though module B doesn't depend on module A! Why? Because the linker decided to go with module B's instance of foo::bar instead of module A's instance at link time. Is this particular scenario valid? Or should one module's static init never trigger static init in another module?

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• Can I load a UIImage from a URL?

  - by progrmr

  I have a URL for an image (got it from UIImagePickerController) but I no longer have the image in memory (the URL was saved from a previous run of the app). Can I reload the UIImage from the URL again? I see that UIImage has a imageWithContentsOfFile: but I have a URL. Can I use NSData's dataWithContentsOfURL: to read the URL? EDIT based on @Daniel's answer I tried the following code but it doesn't work... NSLog(@"%s %@", __PRETTY_FUNCTION__, photoURL); if (photoURL) { NSURL* aURL = [NSURL URLWithString:photoURL]; NSData* data = [[NSData alloc] initWithContentsOfURL:aURL]; self.photoImage = [UIImage imageWithData:data]; [data release]; } When I ran it the console shows: -[PhotoBox willMoveToWindow:] file://localhost/Users/gary/Library/Application%20Support/iPhone%20Simulator/3.2/Media/DCIM/100APPLE/IMG_0004.JPG *** -[NSURL length]: unrecognized selector sent to instance 0x536fbe0 *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSURL length]: unrecognized selector sent to instance 0x536fbe0' Looking at the call stack, I'm calling URLWithString, which calls URLWithString:relativeToURL:, then initWithString:relativeToURL:, then _CFStringIsLegalURLString, then CFStringGetLength, then forwarding_prep_0, then forwarding, then -[NSObject doesNotRecognizeSelector]. Any ideas why my NSString (photoURL's address is 0x536fbe0) doesn't respond to length? Why does it say it doesn't respond to -[NSURL length]? Doesn't it know that param is an NSString, not a NSURL?

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• Fastest way to modify a decimal-keyed table in MySQL?

  - by javanix

  I am dealing with a MySQL table here that is keyed in a somewhat unfortunate way. Instead of using an auto increment table as a key, it uses a column of decimals to preserve order (presumably so its not too difficult to insert new rows while preserving a primary key and order). Before I go through and redo this table to something more sane, I need to figure out how to rekey it without breaking everything. What I would like to do is something that takes a list of doubles (the current keys) and outputs a list of integers (which can be cast down to doubles for rekeying). For example, input {1.00, 2.00, 2.50, 2.60, 3.00} would give output {1, 2, 3, 4, 5). Since this is a database, I also need to be able to update the rows nicely: UPDATE table SET `key`='3.00' WHERE `key`='2.50'; Can anyone think of a speedy algorithm to do this? My current thought is to read all of the doubles into a vector, take the size of the vector, and output a new vector with values from 1 => doubleVector.size. This seems pretty slow, since you wouldn't want to read every value into the vector if, for instance, only the last n/100 elements needed to be modified. I think there is probably something I can do in place, since only values after the first non-integer double need to be modified, but I can't for the life of me figure anything out that would let me update in place as well. For instance, setting 2.60 to 3.00 the first time you see 2.50 in the original key list would result in an error, since the key value 3.00 is already used for the table.

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• actionscript-3: refactor interface inheritance to get rid of ambiguous reference error

  - by maxmc

  hi! imagine there are two interfaces arranged via composite pattern, one of them has a dispose method among other methods: interface IComponent extends ILeaf { ... function dispose() : void; } interface ILeaf { ... } some implementations have some more things in common (say an id) so there are two more interfaces: interface ICommonLeaf extends ILeaf { function get id() : String; } interface ICommonComponent extends ICommonLeaf, IComponent { } so far so good. but there is another interface which also has a dispose method: interface ISomething { ... function dispose() : void; } and ISomething is inherited by ICommonLeaf: interface ICommonLeaf extends ILeaf, ISomething { function get id() : String; } As soon as the dispose method is invoked on an instance which implements the ICommonComponent interface, the compiler fails with an ambiguous reference error because ISomething has a method called dispose and ILeaf also has a dispose method, both living in different interfaces (IComponent, ISomething) within the inheritace tree of ICommonComponent. I wonder how to deal with the situation if the IComponent, the ILeaf and the ISomething can't change. the composite structure must also work for for the ICommonLeaf & ICommonComponent implementations and the ICommonLeaf & ICommonComponent must conform to the ISomething type. this might be an actionscript-3 specific issue. i haven't tested how other languages (for instance java) handle stuff like this.

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• How to get a handle to all JCheckBox objects in order to loop?

  - by EmmyS

  I'm very new to Java and am having some issues looping through JCheckBoxes on a UI. The idea is that I have a bunch of checkboxes (not in a group because more than one can be selected.) When I click a JButton, I want to build a string containing the text from each selected checkbox. The issue I'm having is that our instructor told us that the checkboxes need to be created via a method, which means (see code below) that there isn't a discrete instance name for each checkbox. If there were, I could say something like if(checkBox1.isSelected()) { myString.append(checkBox.getText()); } That would repeat for checkBox2, checkBox3, and so on. But the method provided to us for adding checkboxes to a panel looks like this: public class CheckBoxPanel extends JPanel { private static final long serialVersionUID = 1L; public CheckBoxPanel(String title, String... options) { setBorder(BorderFactory.createTitledBorder(BorderFactory .createEtchedBorder(), title)); setLayout(new BoxLayout(this, BoxLayout.Y_AXIS)); // make one checkbox for each option for (String option : options) { JCheckBox b = new JCheckBox(option); b.setActionCommand(option); add(b); } } } This is called like this: toppingPanel = new CheckBoxPanel("Each Topping $1.50", "Tomato", "Green Pepper", "Black Olives", "Mushrooms", "Extra Cheese", "Pepperoni", "Sausage"); So I now have a panel that contains a border with the title "Each Topping $1.50", and 7 visible checkboxes. What I need to do is get a list of all the selected toppings. We are not supposed to use an ActionListener for each checkbox, but rather get the list when a button is clicked. I'm feeling really clueless here, but I just can't figure out how to get the isSelected property of the checkboxes when the individual checkboxes don't have instance names. Ideally I'd like to somehow add all the checkboxes to an array and loop through the array in the button's action listener to determine which ones are checked, but if I have to check each one individually I will. I just can't figure out how to refer to an individual checkbox when they've been created dynamically.

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• Configure all hosts, then create a list of the config for all hosts?

  - by AME

  I deployed a huge number of hosts with Ansible - which did work very nice. Each host got its individual settings and configuration. Now I'd like to generate a config file for another system that uses these hosts. For it, I need for every host a part of the generated configuration (the one that configures the database). Here is an example of the situation with two hosts having different configuration and the other system that uses a part of the Ansible-generated configuration: host1 ansible configured dbA host2 ansible configured dbQ The other system: host1 = dbA host2 = dbQ The values are computed differently (dbQ instead of dbB for host2 for example) if it belongs in a different cluster and so on, making it unpractical to just read out host configuration from the host_vars. I believe I would need to iterate over the hosts and let Ansible figure out the computed values for the variables like it would when deploying, but I do not know how to put that result in one template. Please advise :)

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• Should I define a single "DataContext" and pass references to it around or define muliple "DataConte

  - by Nate Bross

  I have a Silverlight application that consists of a MainWindow and several classes which update and draw images on the MainWindow. I'm now expanding this to keep track of everything in a database. Without going into specifics, lets say I have a structure like this: MainWindow Drawing-Surface Class1 -- Supports Drawing DataContext + DataServiceCollection<T> w/events Class2 -- Manages "transactions" (add/delete objects from drawing) Class3 Each "Class" is passed a reference to the Drawing Surface so they can interact with it independently. I'm starting to use WCF Data Services in Class1 and its working well; however, the other classes are also going to need access to the WCF Data Services. (Should I define my "DataContext" in MainWindow and pass a reference to each child class?) Class1 will need READ access to the "transactions" data, and Class2 will need READ access to some of the drawing data. So my question is, where does it make the most sense to define my DataContext? Does it make sense to: Define a "global" WCF Data Service "Context" object and pass references to that in all of my subsequent classes? Define an instance of the "Context" for each Class1, Class2, etc Have each method that requires access to data define its own instance of the "Context" and use closures handle the async load/complete events? Would a structure like this make more sense? Is there any danger in keeping an active "DataContext" open for an extended period of time? Typical usecase of this application could range from 1 minute to 40+ minutes. MainWindow Drawing-Surface DataContext Class1 -- Supports Drawing DataServiceCollection<DrawingType> w/events Class2 -- Manages "transactions" (add/delete objects from drawing) DataServiceCollection<TransactionType> w/events Class3 DataServiceCollection<T> w/events

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• DataGrid Column names don't seem to be binding

  - by Jason

  Sort of a Flex newbie here so bear with me. I've got a DataGrid defined as follows: <mx:Script> ... private function getColumns(names:ArrayCollection):Array { var ret:Array = new Array(); for each (var name:String in names) { var column:DataGridColumn = new DataGridColumn(name); ret.push(column); } return ret; } </mx:Script> <mx:DataGrid id="grid" width="100%" height="100%" paddingTop="0" columns="{getColumns(_dataSetLoader.columnNames)}" horizontalScrollPolicy="auto" labelFunction="labelFunction" dataProvider="{_dataSetLoader.data}" /> ...where _dataSetLoader is an instance of an object that looks like: [Bindable] public class DataSetLoader extends EventDispatcher { ... private var _data:ArrayCollection = new ArrayCollection(); private var _columnNames:ArrayCollection = new ArrayCollection(); ... public function reset():void { _status = NOTLOADED; _data.removeAll(); _columnNames.removeAll(); } ... When reset() is called on the dataSetLoader instance, the DataGrid empties the data in the cells, as expected, but leaves the column names, even though reset() calls _columnNames.removeAll(). Shouldn't the change in the collection trigger a change in the DataGrid?

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• Javascript onclick stops working, multiple dynamically created divs.

  - by Patrick

  I have run into a strange problem, i am creating a lot of dynamically divs. And i recently found out that some of my divs doesn't fire the onclick event? All the divs are created using the same template, so why are some not working? Most of the time, its the 4-5 from the bottom. If you click on one of the others and then try again, you might get one of those to trigger. But only sporadically. Code to create the divs: GameField.prototype.InitField = function(fieldNumber) { var newField = document.createElement("div"); if (fieldNumber == 0 || fieldNumber == 6 || fieldNumber == 8 || fieldNumber == 17) newField.className = 'gameCellSmall borderFull gameText gameTextAlign'; else newField.className = 'gameCellSmall borderWithoutTop gameText gameTextAlign'; var instance = this; if (fieldNumber == 6 || fieldNumber == 7 || fieldNumber == 17) { } else newField.onclick = function() { instance.DivClick(fieldNumber); return false; } this.fields[fieldNumber] = newField; this.score[fieldNumber] = 0; return newField; } I added the return false to the click function, but it still behaves strangely. Why are some not triggering? I create around 18 divs / player. But it happens even if i just create one player. Do i perhaps need to cancel the event once i am done with it? (Like the return false; is trying to do)

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• Segmentation Fault with mod_include

  - by Benedikt Eger

  Hi, I'm using a rather complex structure with multiple ssi-includes, set- and echo-commands. The first document writes a lot of set-commands, includes another document which then again includes a third document. On the last included document the variable values are printed using the echo-command. I noticed that with an increasing number of variables the probability for a segmentation fault to happen rises. Did anyone experience something similar? How do I go about debugging such a problem? I'm using IBM_HTTP_Server/2.0.47.1-PK65782 Apache/2.0.47

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• WPF : Access Application Resources when not referencing Shell from App.xaml

  - by CF_Maintainer

  I am beginner in WPF. My App.xaml looks like below app.xaml <Application x:Class="ContactManager.App" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"> <Application.Resources> <Color x:Key="lightBlueColor">#FF145E9D</Color> <SolidColorBrush x:Key="lightBlueBrush" Color="{StaticResource lightBlueColor}" /> </Application.Resources> I do not set the startupuri since I want to a presenter first approach. I do the following in app.xaml.cs protected override void OnStartup(StartupEventArgs e) { base.OnStartup(e); var appPresenter = new ApplicationPresenter( new Shell(), new ContactRepository()); appPresenter.LaunchView(); } I have a usercontrol called "SearchBar.xaml" which references "lightBlueBrush" as a staticResource. When I try to open "Shell.xaml" in the designer it tells me : The "shell.xaml" cannot be loaded at design time because it says it could not create an instance of type "SearchBar.xaml". When I debugged the devenv.exe using another visual studio instance it tells me that it does not have access to the Brush I created in app.resources. If one is doing a Presenter first approach, how does one access resources? I had this working when the startupURI was "Shell.xaml" and the startup event was not present. Any clues/ideas/suggestions. I am just trying to understand. Everything works as expected when I run the application just not @ design time.

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• Which tools to use and how to find file descriptors leaking from Glassfish?

  - by cclark

  We release new code to production every week and Glassfish hasn't had any problems. This weekend we had to move racks at our hosting provider. There were not any code changes (they just powered off, moved, re-racked and powered on) but we're on a new network infrastructure and suddenly we're leaking file descriptors like a sieve. So I'm guessing there is some sort of connection attempting to be made which now fails due to a network change. I'm running Glassfish v2ur2-b04/AS9.1_02 on RHEL4 with an embedded IMQ instance. After the move I started seeing: [#|2010-04-25T05:34:02.783+0000|SEVERE|sun-appserver9.1|javax.enterprise.system.container.web|_ThreadID=33;_ThreadName=SelectorThread-?4848;_RequestID=c4de6f6d-c1d6-416d-ac6e-49750b1a36ff;|WEB0756: Caught exception during HTTP processing. java.io.IOException: Too many open files at sun.nio.ch.ServerSocketChannelImpl.accept0(Native Method) ... [#|2010-04-25T05:34:03.327+0000|WARNING|sun-appserver9.1|javax.enterprise.system.stream.err|_ThreadID=34;_ThreadName=Timer-1;_RequestID=d27e1b94-d359-4d90-a6e3-c7ec49a0f383;|java.lang.NullPointerException at com.sun.jbi.management.system.AutoAdminTask.pollAutoDirectory(AutoAdminTask.java:1031) Using lsof I check the number of file descriptors and I see quite a few entries which look like: java 18510 root 8556u sock 0,4 1555182 can't identify protocol java 18510 root 8557u sock 0,4 1555320 can't identify protocol java 18510 root 8558u sock 0,4 1555736 can't identify protocol java 18510 root 8559u sock 0,4 1555883 can't identify protocol If I do a count of open file descriptors every minute I see it growing by 12 every minute. I have no idea what these sockets are. I've undeployed my application so there is only a plain Glassfish instance running and I still see it leaking 12 file descriptors a minute. So I think this leak is in Glassfish or potentially IMQ. What approach should I take to tracking down these sockets of unknown protocol? What tools can I use (or flags can I pass to lsof) to get more information about where to look? thanks, chuck

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• Entity Framework Generic Repository Error

  - by Jeff Ancel

  I am trying to create a very generic generics repository for my Entity Framework repository that has the basic CRUD statements and uses an Interface. I have hit a brick wall head first and been knocked over. Here is my code, written in a console application, using a Entity Framework Model, with a table named Hurl. Simply trying to pull back the object by its ID. Here is the full application code. using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Data.Objects; using System.Linq.Expressions; using System.Reflection; using System.Data.Objects.DataClasses; namespace GenericsPlay { class Program { static void Main(string[] args) { var hs = new HurlRepository(new hurladminEntity()); var hurl = hs.Load<Hurl>(h => h.Id == 1); Console.Write(hurl.ShortUrl); Console.ReadLine(); } } public interface IHurlRepository { T Load<T>(Expression<Func<T, bool>> expression); } public class HurlRepository : IHurlRepository, IDisposable { private ObjectContext _objectContext; public HurlRepository(ObjectContext objectContext) { _objectContext = objectContext; } public ObjectContext ObjectContext { get { return _objectContext; } } private Type GetBaseType(Type type) { Type baseType = type.BaseType; if (baseType != null && baseType != typeof(EntityObject)) { return GetBaseType(type.BaseType); } return type; } private bool HasBaseType(Type type, out Type baseType) { Type originalType = type.GetType(); baseType = GetBaseType(type); return baseType != originalType; } public IQueryable<T> GetQuery<T>() { Type baseType; if (HasBaseType(typeof(T), out baseType)) { return this.ObjectContext.CreateQuery<T>("[" + baseType.Name.ToString() + "]").OfType<T>(); } else { return this.ObjectContext.CreateQuery<T>("[" + typeof(T).Name.ToString() + "]"); } } public T Load<T>(Expression<Func<T, bool>> whereCondition) { return this.GetQuery<T>().Where(whereCondition).First(); } public void Dispose() { if (_objectContext != null) { _objectContext.Dispose(); } } } } Here is the error that I am getting: System.Data.EntitySqlException was unhandled Message="'Hurl' could not be resolved in the current scope or context. Make sure that all referenced variables are in scope, that required schemas are loaded, and that namespaces are referenced correctly., near escaped identifier, line 3, column 1." Source="System.Data.Entity" Column=1 ErrorContext="escaped identifier" ErrorDescription="'Hurl' could not be resolved in the current scope or context. Make sure that all referenced variables are in scope, that required schemas are loaded, and that namespaces are referenced correctly." This is where I am attempting to extract this information from. http://blog.keithpatton.com/2008/05/29/Polymorphic+Repository+For+ADONet+Entity+Framework.aspx

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• MalformedURLException with file URI

  - by Paul Reiners

  While executing the following code: doc = builder.parse(file); where doc is an instance of org.w3c.dom.Document and builder is an instance of javax.xml.parsers.DocumentBuilder, I'm getting the following exception: Exception in thread "main" java.net.MalformedURLException: unknown protocol: c at java.net.URL.<init>(Unknown Source) at java.net.URL.<init>(Unknown Source) at java.net.URL.<init>(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLEntityManager.setupCurrentEntity(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLEntityManager.startEntity(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLEntityManager.startDTDEntity(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLDTDScannerImpl.setInputSource(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$DTDDriver.dispatch(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$DTDDriver.next(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$PrologDriver.next(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source) at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source) at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source) at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(Unknown Source) at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(Unknown Source) at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(Unknown Source) at javax.xml.parsers.DocumentBuilder.parse(Unknown Source) at com.acme.ItemToThetaValues.createFiles(ItemToThetaValues.java:47) It's choking on this line of the file: <!DOCTYPE questestinterop SYSTEM "C:\Program Files\Acme\parsers\acme_full.dtd"> I am not getting this error on my machine, while a user is getting it on his machine. We are both using version 6 of the Sun JRE. This error also occurs when he's uses double backslashes in the path instead of single backslashes and when he uses forward slashes instead of backslashes. First of all, is the XML correct? Is the path expressed correctly? Second of all, why is this error occurring on one computer but not on another?

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• Java: Initializing a public static field in superclass that needs a different value in every subclas

  - by BinaryMuse

  Good evening, I am developing a set of Java classes so that a container class Box contains a List of a contained class Widget. A Widget needs to be able to specify relationships with other Widgets. I figured a good way to do this would be to do something like this: public abstract class Widget { public static class WidgetID { // implementation stolen from Google's GWT private static int nextHashCode; private final int index; public WidgetID() { index = ++nextHashCode; } public final int hashCode() { return index; } } public abstract WidgetID getWidgetID(); } so sublcasses of Widget could: public class BlueWidget extends Widget { public static final WidgetID WIDGETID = new WidgetID(); @Override public WidgetID getWidgetID() { return WIDGETID; } } Now, BlueWidget can do getBox().addWidgetRelationship(RelationshipTypes.SomeType, RedWidget.WIDGETID, and Box can iterate through it's list comparing the second parameter to iter.next().getWidgetID(). Now, all this works great so far. What I'm trying to do is keep from having to declare the public static final WidgetID WIDGETID in all the subclasses and implement it instead in the parent Widget class. The problem is, if I move that line of code into Widget, then every instance of a subclass of Widget appears to get the same static final WidgetID for their Subclassname.WIDGETID. However, making it non-static means I can no longer even call Subclassname.WIDGETID. So: how do I create a static WidgetID in the parent Widget class while ensuring it is different for every instance of Widget and subclasses of Widget? Or am I using the wrong tool for the job here? Thanks!

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• Using XPath on String in Android (JAVA)

  - by Rav

  I am looking for some examples of using xpath in Android? Or if anyone can share their experiences. I have been struggeling to make tail or head of this problem :-( I have a string that contains a standard xml file. I believe I need to convert that into an xml document. I have found this code which I think will do the trick: public static Document stringToDom(String xmlSource) throws SAXException, ParserConfigurationException, IOException { DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); DocumentBuilder builder = factory.newDocumentBuilder(); return builder.parse(new InputSource(new StringReader(xmlSource))); } Next steps Assuming the code above is OK, I need to apply xpath to get values from cat: "/animal/mammal/feline/cat" I look at the dev doc here: http://developer.android.com/reference/javax/xml/xpath/XPath.html and also look online, but I am not sure where to start! I have tried to use the following code: XPathFactory xPathFactory = XPathFactory.newInstance(); // To get an instance of the XPathFactory object itself. XPath xPath = xPathFactory.newXPath(); // Create an instance of XPath from the factory class. String expression = "SomeXPathExpression"; XPathExpression xPathExpression = xPath.compile(expression); // Compile the expression to get a XPathExpression object. Object result = xPathExpression.evaluate(xmlDocument); // Evaluate the expression against the XML Document to get the result. But I get "Cannot be resolved". Eclipse doesn't seem to be able to fix this import. I tried manually entering: javax.xml.xpath.XPath But this did not work. Does anyone know any good source code that I can utilise, for Android platform? 1.5

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• Scrollbar with Sprite and Rectangle won't move text, just the Rectangle it's painted on.

  - by WebDevHobo

  Warning: school assignment. For those of you still with me, I am tasked with making some scrollable content in Flash. Load in a TextFile using LoadURL(), then display it. To get the text, we've written our own class TextFieldExtended, which is basically just there to give the textfile location to the constructor and then have the class do the various steps of getting it and loading it for you. So I needed to get a Scrollbar, which I got here: http://kirupa.com/forum/showthread.php?t=245468 (all files in a zip linked at the end of this text) The thing is, it works with Sprites. After trying to get it to accept TextFieldExtended, I bumped into a block, since the scrollbar relied heavily on a Sprite property that TextFieldExtended didn't have or could have. So I tried adding the TextFieldExtended instance to a Sprite instance using addchild. A problem occurs here that I do not know how to handle. It seems that a Rectangle is drawn and the Text is drawn on that. I say this because the scrollbar moves the Rectangle up and down a bit, but the text doesn't scroll, just the Rectangle it is positioned in and the text then moves along with it. My question: can this be fixed, or is does this implementation of scrollbars need a lot of adaptations before this is possible? If so, any scrollbars you can recommend, because it's too extended for me at this point. All files: http://www.mediafire.com/?q2ium22gmox This was made in Flash CS4 using ActionScript3. The Example class is the final implementation

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• Caching Authentication Data

  - by PartlyCloudy

  Hi, I'm currently implementing a REST web service using CouchDB and RESTlet. The RESTlet layer is mainly for authentication and some minor filtering of the JSON data served by CouchDB: Clients <= HTTP = [ RESTlet <= HTTP = CouchDB ] I'm using CouchDB also to store user login data, because I don't want to add an additional database server for that purpose. Thus, each request to my service causes two CouchDB requests conducted by RESTlet (auth data + "real" request). In order to keep the service as efficent as possible, I want to reduce the number of requests, in this case redundant requests for login data. My idea now is to provide a cache (i.e.LRU-Cache via LinkedHashMap) within my RESTlet application that caches login data, because HTTP caching will probabily not be enough. But how do I invalidate the cache data, once a user changes the password, for instance. Thanks to REST, the application might run on several servers in parallel, and I don't want to create a central instance just to cache login data. Currently, I save requested auth data in the cache and try to auth new requests by using them. If a authentication fails or there is now entry available, I'll dispatch a GET request to my CouchDB storage in order to obtain the actual auth data. So in a worst case, users that have changed their data will perhaps still be able to login with their old credentials. How can I deal with that? Or what is a good strategy to keep the cache(s) up-to-date in general? Thanks in advance.

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• How to make active services highly available?

  - by Jader Dias

  I know that with Network Load Balancing and Failover Clusteringwe can make passive services highly available. But what about active apps? Example: One of my apps retrieves some content from a external resource in a fixed interval. I have imagined the following scenarios: Run it in a single machine. Problem: if this instance falls, the content won't be retrieved Run it in each machine of the cluster. Problem: the content will be retrieved multiple times Have it in each machine of the cluster, but run it only in one of them. Each instance will have to check some sort of common resource to decide whether it its turn to do the task or not. When I was thinking about the solution #3 I have wondered what should be the common resource. I have thought of creating a table in the database, where we could use it to get a global lock. Is this the best solution? How does people usually do this? By the way it's a C# .NET WCF app running on Windows Server 2008

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• How do I populate a MEF plugin with data that is not hard coded into the assembly?

  - by hjoelr

  I am working on a program that will communicate with various pieces of hardware. Because of the varied nature of the items it communicates and controls, I need to have a different "driver" for each different piece of hardware. This made me think that MEF would be a great way to make those drivers as plugins that can be added even after the product has been released. I've looked at a lot of examples of how to use MEF, but the question that I haven't been able to find an answer to is how to populate a MEF plugin with external data (eg. from a database). All the examples I can find have the "data" hard-coded into the assembly, like the following example: [Export( typeof( IRule ) )] public class RuleInstance : IRule { public void DoIt() {} public string Name { get { return "Rule Instance 3"; } } public string Version { get { return "1.1.0.0"; } } public string Description { get { return "Some Rule Instance"; } } } What if I want Name, Version and Description to come from a database? How would I tell MEF where to get that information? I may be missing something very obvious, but I don't know what it is. Thanks! Joel

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• Problem bounding name to a class in Django

  - by martinthenext

  Hello! I've got a view function that has to decide which form to use depending on some conditions. The two forms look like that: class OpenExtraForm(forms.ModelForm): class Meta: model = Extra def __init__(self, *args, **kwargs): super(OpenExtraForm, self).__init__(*args, **kwargs) self.fields['opening_challenge'].label = "lame translation" def clean_opening_challenge(self): challenge = self.cleaned_data['opening_challenge'] if challenge is None: raise forms.ValidationError('??????? ???, ??????????? ?????? ???. ???????????') return challenge class HiddenExtraForm(forms.ModelForm): class Meta: model = Extra exclude = ('opening_challenge') def __init__(self, *args, **kwargs): super(HiddenExtraForm, self).__init__(*args, **kwargs) The view code goes like that: @login_required def manage_extra(request, extra_id=None, hidden=False): if not_admin(request.user): raise Http404 if extra_id is None: # Adding a new extra extra = Extra() if hidden: FormClass = HiddenExtraForm else: FormClass = OpenExtraForm else: # Editing an extra extra = get_object_or_404(Extra, pk=extra_id) if extra.is_hidden(): FromClass = HiddenExtraForm else: FormClass = OpenExtraForm if request.POST: form = FormClass(request.POST, instance=extra) if form.is_valid(): form.save() return HttpResponseRedirect(reverse(view_extra, args=[extra.id])) else: form = FormClass(instance=extra) return render_to_response('form.html', { 'form' : form, }, context_instance=RequestContext(request) ) The problem is somehow if extra.is_hidden() returns True, the statement FromClass = HiddenExtraForm doesn't work. I mean, in all other conditions that are used in the code it works fine: the correct Form classes are intantiated and it all works. But if extra.is_hidden(), the debugger shows that the condition is passed and it goes to the next line and does nothing! As a result I get a UnboundLocalVar error which says FormClass hasn't been asssigned at all. Any ideas on what's happening?

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• State Animation on ListBox ItemTemplate

  - by Peanut

  I have a listbox which reads from Observable collection, and is ItemTemplate'ed: <DataTemplate x:Key="DataTemplate1"> <Grid x:Name="grid" Height="47.333" Width="577" Opacity="0.495"> <Image HorizontalAlignment="Left" Margin="10.668,8,0,8" Width="34" Source="{Binding ImageLocation}"/> <TextBlock Margin="56,8,172.334,8" TextWrapping="Wrap" Text="{Binding ApplicationName}" FontSize="21.333"/> <Grid x:Name="grid1" HorizontalAlignment="Right" Margin="0,10.003,-0.009,11.33" Width="26" Opacity="0" RenderTransformOrigin="0.5,0.5"> <Image HorizontalAlignment="Stretch" Margin="0" Source="image/downloads.png" Stretch="Fill" MouseDown="Image_MouseDown" /> </Grid> </Grid> </DataTemplate> <ListBox x:Name="searchlist" Margin="8" ItemTemplate="{DynamicResource DataTemplate1}" ItemsSource="{Binding SearchResults}" SelectionChanged="searchlist_SelectionChanged" ItemContainerStyle="{DynamicResource ListBoxItemStyle1}" /> In general, my question is "What is the easiest way to do Animation on Particular Items in this listbox As they are selected? Basically the image inside the "grid1" will be setting its opacity to 1, slowly. I would prefer to use states, but I do not know of any way to just tell blend and xaml to "When a selected item is changed, change the image opacity to 1 over a period of .3 seconds". Infact, I have been doing this in the .cs file using the VisualStateManager. Also, there is another issue. When the selected index is changed, we goto the CS file and look at SelectedItem. SelectedItem returns an instance of the Object in which it was bound to (The object inside the observable collection), and NOT an instance of the DataTemplate/ListItem etc. So how am I able to pull the correct image out of this list? State animation with VisualStateManager I can handle fine if its just normal things, but when it comes to generated listboxes' items, I'm lost. Thanks

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