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• Our embedded linux system won't recognize a USB Device if it is plugged in before powerup. Suggestions?

  - by Blaine

  We are developing on a small embedded device. This device us a gumstix overo board running OpenEmbedded linux. We have our development almost completely done, and have run into the strangest of bugs that we can't figure out. We have a USB Device (Spectrophotometer) that has a USB2.0 Connection and an external power supply for the light source. Typical behavior is that you plug in the power supply, then the USB connection to a host. When the usb connection is detected by the device, the device boots up and enables the light source and fan. The device is then able to be used by the host system. The problem is that if the device is plugged into the Gumstix before we turn on the Gumstix, the USB Device apparently is not probed by the system (and hence does not turn on). Under a normal situation, when the connection is initialized by plugging in the usb cable, the spectro turns itself on and becomes available to the system (this can be seen via "lsusb" typically). Neither of these things are happening. There is no device detected via "lsusb" and no dmesg errors of any kind that we can see. It is as if the device is not plugged in. The device does show up and work fine if we unplug the USB cable and plug it back in once the system is booted up. It turns on and shows up on the usb bus, and we can access it with our driver. On any other desktop or laptop, it does not matter if the host system is on or off when we plug in the spectrometer. This behavior is what I would consider to be "normal" - that the usb system is probed and initialized at boot time, and the usb devices come online. In other words, our system is fully functional as long as we plug in the usb device after the system is booted up. Unfortunately this isn't possible in our final product - everything comes on at once. Additional Info: 1) We have tried a flash drive attached to the system when the system is turned off. Booting up the system brings the flash drive online, as expected 2) There are no messages regarding the spectro or usb device (using dmesg). "lsusb" only lists the USB hubs / controllers. It is literally as if the device is not present and not plugged in. 3) We have tried a brand new image from gumstix and an older image from last year. Both images have this problem. This problem exists on all 3 gumstix devices we use. Does anyone have any suggestions? From what I can tell it isn't really possible to do a complete "reboot" of the usb system that is a complete emulation of "unplugging" and "replugging" a usb device. I feel like what is happening is that there is no initial probe on the usb bus that would trigger the usb handshaking, but this is somehow specific to the spectro. This seems to be a kernel issue or at least an issue in how the kernel is initializing the usb subsystem. I'm not really sure though. I have tried the gumstix mailing list, but there doesn't seem to be anyone who has seen this issue before. Any advice or suggestions on where to start looking would be fantastic. Thank you! Blaine output etc. $ uname -a Linux overo 2.6.33 #1 Tue Apr 27 08:35:38 PDT 2010 armv7l GNU/Linux When the system is up and running and spectro is plugged in (working as intended), this is lsusb: Bus 001 Device 116: ID 2457:1022 Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 2.00 bDeviceClass 0 (Defined at Interface level) bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 64 idVendor 0x2457 idProduct 0x1022 bcdDevice 0.02 iManufacturer 1 USB4000 1.01.11 iProduct 2 Ocean Optics USB4000 iSerial 0 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 46 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0x80 (Bus Powered) MaxPower 400mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 4 bInterfaceClass 255 Vendor Specific Class bInterfaceSubClass 0 bInterfaceProtocol 0 iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x01 EP 1 OUT bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x82 EP 2 IN bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x86 EP 6 IN bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Device Qualifier (for other device speed): bLength 10 bDescriptorType 6 bcdUSB 2.00 bDeviceClass 0 (Defined at Interface level) bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 64 bNumConfigurations 1 Device Status: 0x0000 (Bus Powered) dmesg output: usb usb1: usb auto-resume hub 1-0:1.0: hub_resume usb usb2: usb auto-resume ehci-omap ehci-omap.0: resume root hub hub 1-0:1.0: state 7 ports 1 chg 0000 evt 0000 hub 2-0:1.0: hub_resume hub 2-0:1.0: state 7 ports 3 chg 0000 evt 0000 hub 1-0:1.0: hub_suspend usb usb1: bus auto-suspend hub 2-0:1.0: hub_suspend usb usb2: bus auto-suspend ehci-omap ehci-omap.0: suspend root hub usb usb2: usb resume ehci-omap ehci-omap.0: resume root hub hub 2-0:1.0: hub_resume ehci-omap ehci-omap.0: GetStatus port 2 status 001803 POWER sig=j CSC CONNECT hub 2-0:1.0: port 2: status 0501 change 0001 hub 2-0:1.0: state 7 ports 3 chg 0004 evt 0000 hub 2-0:1.0: port 2, status 0501, change 0000, 480 Mb/s ehci-omap ehci-omap.0: port 2 high speed ehci-omap ehci-omap.0: GetStatus port 2 status 001005 POWER sig=se0 PE CONNECT usb 2-2: new high speed USB device using ehci-omap and address 2 ehci-omap ehci-omap.0: port 2 high speed ehci-omap ehci-omap.0: GetStatus port 2 status 001005 POWER sig=se0 PE CONNECT usb 2-2: default language 0x0409 usb 2-2: udev 2, busnum 2, minor = 129 usb 2-2: New USB device found, idVendor=2457, idProduct=1022 usb 2-2: New USB device strings: Mfr=1, Product=2, SerialNumber=0 usb 2-2: Product: Ocean Optics USB4000 usb 2-2: Manufacturer: USB4000 1.01.11 usb 2-2: uevent usb 2-2: usb_probe_device usb 2-2: configuration #1 chosen from 1 choice usb 2-2: uevent usb 2-2: adding 2-2:1.0 (config #1, interface 0) usb 2-2:1.0: uevent drivers/usb/core/inode.c: creating file '002' dmesg has nothing to say, and lusb simply lists nothing else but the two default usb controllers / hubs if we plug the device in before the system is turned on.

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• Are "EXC_BREAKPOINT (SIGTRAP)" exceptions caused by debugging breakpoints?

  - by Dennis

  I have a multithreaded app that is very stable on all my test machines and seems to be stable for almost every one of my users (based on no complaints of crashes). The app crashes frequently for one user, though, who was kind enough to send crash reports. All the crash reports (~10 consecutive reports) look essentially identical: Date/Time: 2010-04-06 11:44:56.106 -0700 OS Version: Mac OS X 10.6.3 (10D573) Report Version: 6 Exception Type: EXC_BREAKPOINT (SIGTRAP) Exception Codes: 0x0000000000000002, 0x0000000000000000 Crashed Thread: 0 Dispatch queue: com.apple.main-thread Thread 0 Crashed: Dispatch queue: com.apple.main-thread 0 com.apple.CoreFoundation 0x90ab98d4 __CFBasicHashRehash + 3348 1 com.apple.CoreFoundation 0x90adf610 CFBasicHashRemoveValue + 1264 2 com.apple.CoreText 0x94e0069c TCFMutableSet::Intersect(__CFSet const*) const + 126 3 com.apple.CoreText 0x94dfe465 TDescriptorSource::CopyMandatoryMatchableRequest(__CFDictionary const*, __CFSet const*) + 115 4 com.apple.CoreText 0x94dfdda6 TDescriptorSource::CopyDescriptorsForRequest(__CFDictionary const*, __CFSet const*, long (*)(void const*, void const*, void*), void*, unsigned long) const + 40 5 com.apple.CoreText 0x94e00377 TDescriptor::CreateMatchingDescriptors(__CFSet const*, unsigned long) const + 135 6 com.apple.AppKit 0x961f5952 __NSFontFactoryWithName + 904 7 com.apple.AppKit 0x961f54f0 +[NSFont fontWithName:size:] + 39 (....more text follows) First, I spent a long time investigating [NSFont fontWithName:size:]. I figured that maybe the user's fonts were screwed up somehow, so that [NSFont fontWithName:size:] was requesting something non-existent and failing for that reason. I added a bunch of code using [[NSFontManager sharedFontManager] availableFontNamesWithTraits:NSItalicFontMask] to check for font availability in advance. Sadly, these changes didn't fix the problem. I've now noticed that I forgot to remove some debugging breakpoints, including _NSLockError, [NSException raise], and objc_exception_throw. However, the app was definitely built using "Release" as the active build configuration. I assume that using the "Release" configuration prevents setting of any breakpoints--but then again I am not sure exactly how breakpoints work or whether the program needs to be run from within gdb for breakpoints to have any effect. My questions are: could my having left the breakpoints set be the cause of the crashes observed by the user? If so, why would the breakpoints cause a problem only for this one user? If not, has anybody else had similar problems with [NSFont fontWithName:size:]? I will probably just try removing the breakpoints and sending back to the user, but I'm not sure how much currency I have left with that user. And I'd like to understand more generally whether leaving the breakpoints set could possibly cause a problem (when the app is built using "Release" configuration).

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• Historical / auditable database

  - by Mark

  Hi all, This question is related to the schema that can be found in one of my other questions here. Basically in my database I store users, locations, sensors amongst other things. All of these things are editable in the system by users, and deletable. However - when an item is edited or deleted I need to store the old data; I need to be able to see what the data was before the change. There are also non-editable items in the database, such as "readings". They are more of a log really. Readings are logged against sensors, because its the reading for a particular sensor. If I generate a report of readings, I need to be able to see what the attributes for a location or sensor was at the time of the reading. Basically I should be able to reconstruct the data for any point in time. Now, I've done this before and got it working well by adding the following columns to each editable table: valid_from valid_to edited_by If valid_to = 9999-12-31 23:59:59 then that's the current record. If valid_to equals valid_from, then the record is deleted. However, I was never happy with the triggers I needed to use to enforce foreign key consistency. I can possibly avoid triggers by using the extension to the "PostgreSQL" database. This provides a column type called "period" which allows you to store a period of time between two dates, and then allows you to do CHECK constraints to prevent overlapping periods. That might be an answer. I am wondering though if there is another way. I've seen people mention using special historical tables, but I don't really like the thought of maintainling 2 tables for almost every 1 table (though it still might be a possibility). Maybe I could cut down my initial implementation to not bother checking the consistency of records that aren't "current" - i.e. only bother to check constraints on records where the valid_to is 9999-12-31 23:59:59. Afterall, the people who use historical tables do not seem to have constraint checks on those tables (for the same reason, you'd need triggers). Does anyone have any thoughts about this? PS - the title also mentions auditable database. In the previous system I mentioned, there is always the edited_by field. This allowed all changes to be tracked so we could always see who changed a record. Not sure how much difference that might make. Thanks.

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• Using array as map value: Cant see the error

  - by Tom

  Hi all, Im trying to create a map, where the key is an int, and the value is an array int red[3] = {1,0,0}; int green[3] = {0,1,0}; int blue[3] = {0,0,1}; std::map<int, int[3]> colours; colours.insert(std::pair<int,int[3]>(GLUT_LEFT_BUTTON,red)); //THIS IS LINE 24 ! colours.insert(std::pair<int,int[3]>(GLUT_MIDDLE_BUTTON,blue)); colours.insert(std::pair<int,int[3]>(GLUT_RIGHT_BUTTON,green)); However, when I try to compile this code, I get the following error. g++ (Ubuntu 4.4.1-4ubuntu8) 4.4.1 In file included from /usr/include/c++/4.4/bits/stl_algobase.h:66, from /usr/include/c++/4.4/bits/stl_tree.h:62, from /usr/include/c++/4.4/map:60, from ../src/utils.cpp:9: /usr/include/c++/4.4/bits/stl_pair.h: In constructor ‘std::pair<_T1, _T2>::pair(const _T1&, const _T2&) [with _T1 = int, _T2 = int [3]]’: ../src/utils.cpp:24: instantiated from here /usr/include/c++/4.4/bits/stl_pair.h:84: error: array used as initializer /usr/include/c++/4.4/bits/stl_pair.h: In constructor ‘std::pair<_T1, _T2>::pair(const std::pair<_U1, _U2>&) [with _U1 = int, _U2 = int [3], _T1 = const int, _T2 = int [3]]’: ../src/utils.cpp:24: instantiated from here /usr/include/c++/4.4/bits/stl_pair.h:101: error: array used as initializer In file included from /usr/include/c++/4.4/map:61, from ../src/utils.cpp:9: /usr/include/c++/4.4/bits/stl_map.h: In member function ‘_Tp& std::map<_Key, _Tp, _Compare, _Alloc>::operator[](const _Key&) [with _Key = int, _Tp = int [3], _Compare = std::less<int>, _Alloc = std::allocator<std::pair<const int, int [3]> >]’: ../src/utils.cpp:30: instantiated from here /usr/include/c++/4.4/bits/stl_map.h:450: error: conversion from ‘int’ to non-scalar type ‘int [3]’ requested make: *** [src/utils.o] Error 1 I really cant see where the error is. Or even if there's an error. Any help (please include an explanation to help me avoid this mistake) will be appreciated. Thanks in advance.

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• NHibernate criteria query question

  - by Chris

  I have 3 related objects (Entry, GamePlay, Prize) and I'm trying to find the best way to query them for what I need using NHibernate. When a request comes in, I need to query the Entries table for a matching entry and, if found, get a) the latest game play along with the first game play that has a prize attached. Prize is a child of GamePlay and each Entry object has a GamePlays property (IList). Currently, I'm working on a method that pulls the matching Entry and eagerly loads all game plays and associated prizes, but it seems wasteful to load all game plays just to find the latest one and any that contain a prize. Right now, my query looks like this: var entry = session.CreateCriteria<Entry>() .Add(Restrictions.Eq("Phone", phone)) .AddOrder(Order.Desc("Created")) .SetFetchMode("GamePlays", FetchMode.Join) .SetMaxResults(1).UniqueResult<Entry>(); Two problems with this: It loads all game plays up front. With 365 days of data, this could easily balloon to 300k of data per query. It doesn't eagerly load the Prize child property for each game. Therefore, my code that loops through the GamePlays list looking for a non-null Prize must make a call to load each Prize property I check. I'm not an nhibernate expert, but I know there has to be a better way to do this. Ideally, I'd like to do the following (pseudocode): entry = findEntry(phoneNumber) lastPlay = getLatestGamePlay(Entry) firstWinningPlay = getFirstWinningGamePlay(Entry) The end result of course is that I have the entry details, the latest game play, and the first winning game play. The catch is that I want to do this in as few database calls as possible, otherwise I'd just execute 3 separate queries. The object definitions look like: public class Entry { public Guid Id {get;set;} public string Phone {get;set;} public IList<GamePlay> GamePlays {get;set;} // ... other properties } public class GamePlay { public Guid Id {get;set;} public Entry Entry {get;set;} public Prize Prize {get;set;} // ... other properties } public class Prize { public Guid Id {get;set;} // ... other properties } The proper NHibernate mappings are in place, so I just need help figuring out how to set up the criteria query (not looking for HQL, don't use it).

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• Hosting a WCF Service Lib through a Windows service get a System.InvalidOperationException: attempti

  - by JohnL

  I have a WCF Service Library containing five service contracts. The library is hosted through a Windows Service. Most if not all my configuration for the WCF Library is declaritive. The only thing I am doing in code for configuration is to pass the type of the class implementing the service contracts into ServiceHost. I then call Open on each of the services during the Windows Service OnStart event. Here is the error message I get: Service cannot be started. System.InvalidOperationException: Service '[Fubu.Conversion.Service1' has zero application (non-infrastructure) endpoints. This might be because no configuration file was found for your application, or because no service element matching the service name could be found in the configuration file, or because no endpoints were defined in the service element. at System.ServiceModel.Description.DispatcherBuilder.EnsureThereAreNonMexEndpoints(ServiceDescription description) at System.ServiceModel.Description.DispatcherBuilder.InitializeServiceHost(ServiceDescription description, ServiceHostBase serviceHost) at System.ServiceModel.ServiceHostBase.InitializeRuntime() at System.ServiceModel.ServiceHostBase.OnBeginOpen() at System.ServiceModel.ServiceHostBase.OnOpen(TimeSpan timeout) at System.ServiceModel.Channels.CommunicationObject.Open(TimeSpan timeout) at System.ServiceModel.Channels.CommunicationObject.Open() at Fubu.RemotingHost.RemotingHost.StartServ... protected override void OnStart(string[] args) { // Uncomment to debug this properly //System.Diagnostics.Debugger.Break(); StartService1(); StartService2(); StartService3(); StartService4(); StartService5(); } Each of the above simply do the following: private void StartSecurityService() { host = new ServiceHost(typeof(Service1)); host.Open(); } Service Lib app.congfig summary <services> <service behaviorConfiguration="DefaultServiceBehavior" name="Fubu.Conversion.Service1"> <endpoint address="" binding="netTcpBinding" bindingConfiguration="TCPBindingConfig" name="Service1" bindingName="TCPEndPoint" contract="Fubu.Conversion.IService1"> <identity> <dns value="localhost" /> </identity> </endpoint> <endpoint address="mex" binding="mexTcpBinding" bindingConfiguration="" name="mexSecurity" bindingName="TcpMetaData" contract="IMetadataExchange" /> <host> <baseAddresses> <add baseAddress="net.tcp://localhost:8025/Fubu/Conversion/Service1/" /> </baseAddresses> </host> </service> ... Contract is set up as follows: namespace Fubu.Conversion.Service1 { [ServiceContract(Namespace = "net.tcp://localhost:8025/Fubu")] public interface IService1 { I have looked "high and low" for a solution without any luck. Is the answer obvious? The solution to this does not appear to be. Thanks

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• Tracking upstream svn changes with git-svn and github?

  - by Joseph Turian

  How do I track upstream SVN changes using git-svn and github? I used git-svn to convert an SVN repo to git on github: $ git svn clone -s http://svn.osqa.net/svnroot/osqa/ osqa $ cd osqa $ git remote add origin [email protected]:turian/osqa.git $ git push origin master I then made a few changes in my git repo, committed, and pushed to github. Now, I am on a new machine. I want to take upstream SVN changes, merge them with my github repo, and push them to my github repo. This documentation says: "If you ever lose your local copy, just run the import again with the same settings, and you’ll get another working directory with all the necessary SVN metainfo." So I did the following. But none of the commands work as desired. How do I track upstream SVN changes using git-svn and github? What am I doing wrong? $ git svn clone -s http://svn.osqa.net/svnroot/osqa/ osqa $ cd osqa $ git remote add origin [email protected]:turian/osqa.git $ git push origin master To [email protected]:turian/osqa.git ! [rejected] master -> master (non-fast forward) error: failed to push some refs to '[email protected]:turian/osqa.git' $ git pull remote: Counting objects: 21, done. remote: Compressing objects: 100% (17/17), done. remote: Total 17 (delta 7), reused 9 (delta 0) Unpacking objects: 100% (17/17), done. From [email protected]:turian/osqa * [new branch] master -> origin/master From [email protected]:turian/osqa * [new tag] master -> master You asked me to pull without telling me which branch you want to merge with, and 'branch.master.merge' in your configuration file does not tell me either. Please name which branch you want to merge on the command line and try again (e.g. 'git pull <repository> <refspec>'). See git-pull(1) for details on the refspec. ... $ /usr//lib/git-core/git-svn rebase warning: refname 'master' is ambiguous. First, rewinding head to replay your work on top of it... Applying: Added forum/management/commands/dumpsettings.py error: Ref refs/heads/master is at 6acd747f95aef6d9bce37f86798a32c14e04b82e but expected a7109d94d813b20c230a029ecd67801e6067a452 fatal: Cannot lock the ref 'refs/heads/master'. Could not move back to refs/heads/master rebase refs/remotes/trunk: command returned error: 1

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• What does N years of experience with a language really mean?

  - by marcgg

  I've been looking at jobs descriptions since I'm graduating soon and looking for a job and what's always coming back - I'm not teaching you anything - is the "N years of experience in this language". It has been discussed in this question that if you work professionally with let's say Ruby for 2 years, but during these two years you also did some C# and PHP and were actually coding in Ruby 50% of the time. Do you say you have 1 year of experience in Ruby? 2 years? Another issue that hasn't been reviewed in the other post is for "non-professional experience". I'll give you a personal example: I've been working with Ruby on Rails since 2004 while at school. I did a lot of personal projects and school projects using this technology. I also used Rails in 2 6-month internships. Do I have 5 years of Rails experience (2004-now)? Do I have 1 year(2 internships)? Do I have nothing? I feel like I don't deserve the credit for 5 years, because the first years I wasn't working a lot with rails, but since last year I launched some websites and invested myself a lot in this technology and just saying 1 year doesn't really reflect how much I know the technology... Another example: I Learned C++ at school and did 1 big project with it (2-3 month of work and a semester of classes). I never used it in a company but I'd be able to be productive fairly quickly if I had to work on a C++ project and I have a good grasp of the concepts. Do I have no experience? 3 months? 6 months? ... something else? What I'm really trying to do is to find a way to present my skill set in a way that is compliant to what recruiters expect. I also don't want to end up at an interview that would go something like this... Recruiter (finding out the horrible truth): Oh but you said that you had 2 years of experience with this when you have none! / slaps me in the face / Me (in pain): Oh! The irony! Recruiter (yelling): Get out of my office / calls security, punches me in the throat /

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• Why won't this hit test fire a second time? wpf

  - by csciguy

  All, I have a main window that contains two custom objects (AnimatedCharacter). These objects are nothing but images. These images might contain transparent portions. One of these objects slightly overlaps the other object. There is a listener attached to the main window and is as follows. private void Window_MouseLeftButtonUp_1(object sender, MouseButtonEventArgs e) { Point pt = e.GetPosition((UIElement)sender); //store off the mouse pt hitPointMouse = pt; //clear the result list hitResultsSubList.Clear(); EllipseGeometry m_egHitArea = new EllipseGeometry(pt, 1, 1); VisualTreeHelper.HitTest(sender as Visual, HitTestFilterFuncNew, new HitTestResultCallback(HitTestCallback), new GeometryHitTestParameters(m_egHitArea)); //Check all sub items you have now hit if (hitResultsSubList.Count > 0) { CheckSubHitItems(hitResultsSubList); } } The idea is to filter out only a select group of items (called AnimatedCharacters). The hittest and filters are as follows public HitTestResultBehavior HitTestCallback(HitTestResult htrResult) { IntersectionDetail idDetail = ((GeometryHitTestResult)htrResult).IntersectionDetail; switch (idDetail) { case IntersectionDetail.FullyContains: return HitTestResultBehavior.Continue; case IntersectionDetail.Intersects: return HitTestResultBehavior.Continue; case IntersectionDetail.FullyInside: return HitTestResultBehavior.Continue; default: return HitTestResultBehavior.Stop; } } public HitTestFilterBehavior HitTestFilterFuncNew(DependencyObject potentialHitTestTarget) { if (potentialHitTestTarget.GetType() == typeof(AnimatedCharacter)) { hitResultsSubList.Add(potentialHitTestTarget as AnimatedCharacter); } return HitTestFilterBehavior.Continue; } This returns me back a list (called hitResultsSubList) that I attempt to then process further. I want to take everything in the hitResultsSubList and run a hit test on it again. This time, the hit test will be checking alpha levels on the particular animatedCharacter object. private void CheckSubHitItems(List<DependencyObject> hitResultsSub) { for(int i = 0; i<hitResultsSub.Count; i++) { hitResultsList.Clear(); AnimatedCharacter ac = hitResultsSub[i] as AnimatedCharacter; try { //DEBUGGER SKIPS THIS NEXT LINE EVERY SINGLE TIME. VisualTreeHelper.HitTest(ac, null, new HitTestResultCallback(hitCallBack), new PointHitTestParameters(hitPointMouse)); } catch (Exception e) { System.Diagnostics.Debug.WriteLine(e.StackTrace); } if (hitResultsList.Count > 0) { //do something here } } } Here is my problem now. The hit test in the second function (CheckSubHitItems) never gets called. There are definitely items (DependencyObjects of the type AnimatedCharacter) in the hitResultSub, but no matter what, the second hit test will not fire. I can walk the for loop fine, but when that line is hit, I get the following console statement. Step into: Stepping over non-user code 'System.MulticastDelegate.CtorClosed' No exceptions are thrown. Any help is appreciated.

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• One entityManger finds entity , the other does not.

  - by Pitelk

  Hi all, I have a very strange behavior in my program. I have 2 classes (class LogIn and CreateGame) where i have injected an EntityManager in each using the annotation @PersistenceContext(unitName="myUnitPU") EntityManager entitymanger; In some point i remove an object called "user" from the database using entitymanger.remove(user) from a method in LogIn class. The business logic is that a user can host and join games ( in the same time) so removing the user all the entries in database about the games the user has created are removed and all the entries showing in which games the user has joined are removed also. After that, i call another function which checks if the user exists using a method in the LogIn class entitymanager.find(user) which surprisingly enough, finds the user. After that I call a method in CreateGame class which tries to find the user by using again entitymanger.find(user) the entitymanger in that class fails to find the user (which is the expected result as the user is removed and it's not in the database) So the question is : Why the entitymanager in one class finds the user (which is wrong) where the other doesn't find it? Does anyone has ever the same problem? PS : This "bug" occurs when the user has hosted a game which is joined by another user (lets call him Buser) and the Buser has made a game which is joined by the current user. GAME | HOST | CLIENTS game1 | user | userB game2 | userB | user where in this case by removing the user, the game1 is deleted and the user is removed from game2 so the result is GAME | HOST | CLIENTS game2 | userB | PS2 : The Beans are EJB3.0. The methods are called from a delegate class. The beans in the delegate class are instantiated using the InitialContext.lookup() method. Note that for logging in ,creating , joining games the appropriate delegate class calls the correspondent EJB which does the transactions. In the case of logOut, the delegate calls an EJB to logout the user but becuase other stuff must be done (as said above) this EJB calls other EJB (again using lookup() ) which has methods like removegame(), removeUserFromGame() etc. After those methods are executed the user is then logged out. Maybe it has something to do with the fact the the first entity manager is called by a delegate but the second from inside an EJb and thats why the one entitymanger can see the non-existent user while the other cannot? Also all the methods have TRANSACTIONTYPE.REQUIRED Thank you in advance

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• ActiveMQ 5.2.0 + REST + HTTP POST = java.lang.OutOfMemoryError

  - by Bruce Loth

  First off, I am a newbie when it comes to JMS & ActiveMQ. I have been looking into a messaging solution to serve as middleware for a message producer that will insert XML messages into a queue via HTTP POST. The producer is an existing system written in C++ that cannot be modified (so Java and the C++ API are out). Using the "demo" examples and some trial and error, I have cobbled together a working example of what I want to do (on a windows box). The web.xml I configured in a test directory under "webapps" specifies that the HTTP POST messages received from the producer are to be handled by the MessageServlet. I added a line for the text app in "activemq.xml" ('ow' is the test app dir): I created a test script to "insert" messages into the queue which works well. The problem I am running into is that it as I continue to insert messages via REST/HTTP POST, the memory consumption and thread count used by ActiveMQ continues to rise (It happens when I have timely consumers as well as slow or non-existent consumers). When memory consumption gets around 250MB's and the thread count exceeds 5000 (as shown in windows task manager), ActiveMQ crashes and I see this in the log: Exception in thread "ActiveMQ Transport Initiator: vm://localhost#3564" java.lang.OutOfMemoryError: unable to create new native thread It is as if Jetty is spawning a new thread to handle each HTTP POST and the thread never dies. I did look at this page: http://activemq.apache.org/javalangoutofmemory.html and tried but that didn't fix the problem (although I didn't fully understand the implications of the change either). Does anyone have any ideas? Thanks! Bruce Loth PS - I included the "test message producer" python script below for what it is worth. I created batches of 100 messages and continued to run the script manually from the command line while watching the memory consumption and thread count of ActiveMQ in task manager. def foo(): import httplib, urllib body = "<?xml version='1.0' encoding='UTF-8'?>\n \ <ROOT>\n \ [snip: xml deleted to save space] </ROOT>" headers = {"content-type": "text/xml", "content-length": str(len(body))} conn = httplib.HTTPConnection("127.0.0.1:8161") conn.request("POST", "/ow/message/RDRCP_Inbox?type=queue", body, headers) response = conn.getresponse() print response.status, response.reason data = response.read() conn.close() ## end method definition ## Begin test code count = 0; while(count < 100): # Test with batches of 100 msgs count += 1 foo()

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• MySQL table organization and optimization (Rails)

  - by aguynamedloren

  I've been learning Ruby on Rails over the past few months with no prior programming experience. Lately, I've been thinking about database optimization and table organization. I know there are great books on the subject, but I typically learn by example / as I go. Here's a hypothetical situation: Let's say I am building a social network for a niche community with 250,000 members (users). The users have the ability to attend events. Let's say there are 50,000 past/present/future events. Much like Facebook events, a user can attend any number of events and an event can have any number of attendees. In the database, there would be a table for users and a table for events. Somehow I would have to create an association between the users and events. I could create an "events" column in the users table such that each user row would contain a hash of event IDs, or I could create an "attendees" column in the events table such that each event row would contain a hash of user IDs. Neither of these solutions seem ideal, however. On a users profile page, I want to display the list of events they are associated with, which would require scanning the 50,000 event rows for the user ID of said user if I include an "attendees" column in the events table. Likewise, on an event page, I want to display a list of attendees for the event, which would require scanning the 250,000 user rows for the event ID of said event if I include an "events" column in the users table. Option 3 would be to create a third table that contains the attendee information for each and every event - but I don't see how this would solve any problems. Are these non-issues? Rails makes accessing all of this information easy, but I guess I'm worried about scale. It is entirely possible that I am under-estimating the speed and processing power of modern databases / servers / etc. How long would it take to scan 250,000 user rows for specific event IDs - 10ms? 100ms? 1,000ms? I guess that's not that bad. Am I just over-thinking this?

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• Problem getting correct parameters for C# P/Invoke call to C++ dll

  - by Jim Jones

  Trying to Interop a functionality from the Outside In API from Oracle. Have the following function: SCCERR EXOpenExport {VTHDOC hDoc, VTDWORD dwOutputId, VTDWORD dwSpecType, VTLPVOID pSpec, VTDWORD dwFlags, VTSYSPARAM dwReserved, VTLPVOID pCallbackFunc, VTSYSPARAM dwCallbackData, VTLPHEXPORT phExport); From the header files I reduced the parameters to: typedef VTSYSPARAM VTHDOC, VTLPHDOC * typedef DWORD_PTR VTSYSPARAM typedef unsigned long DWORD_PTR typedef unsigned long VTDWORD typedef VTVOID* VTLPVOID #define VTVOID void typedef VTHDOC VTHEXPORT, *VTLPEXPORT These are for 32 bit windows Going through the header files, the example programs, and the documentation I found: 1. That pSpec could be a pointer to a buffer or NULL, so I set it to a IntPtr.Zero (documentation). 2. That dwFlags and dwReserved according to the documentation "Must be set by the developer to 0". 3. That pCallbackFunc can be set to NULL if I don't want to handle callbacks. 4. That the last two are based on structs that I wrote C# wrappers for using the [StructLayout(LayoutKind.Sequential)]. Then instatiated an instance and generated the parameters by first creating a IntPtr with Marshal.AllocHGlobal(Marshal.SizeOf(instance)), then getting the address value which is passed as a uint for dwCallbackData and a IntPtr for phExport. The final parameter list is as follows: 1. phDoc as a IntPtr which was loaded with an address by the DAOpenDocument function called before. 2. dwOutputId as uint set to 1535 which represents FI_JPEGFIF 3. dwSpecType as int set to 2 which represents IOTYPE_ANSIPATH 4. pSpec as an IntPtr.Zero where the output will be written 5. dwFlags as uint set to 0 as directed 6. dwReserved as uint set to 0 as directed 7. pCallbackFunc as IntPtr set to NULL as I will handle results 8. dwCallBackDate as uint the address of a buffer for a struct 9. phExport as IntPtr to another struct buffer still get an undefined error from the API. Meaning that the call returns a 961 which is not defined in any of the header files. In the past I have gotten this when my choice of parameter types are incorrect. I started out using Interop Assistant which was helpful in learning how many of the parameter types get translated. It is however limited by how well I am able to glean the correct native type from the header files. For example the hDoc parameter used in the preceding function was defined as a non-filesytem handle, so attempted to use Marshal to create a handle, then used an IntPtr, and finally it turned out to be an int (actually it was &phDoc used here). So is there a more scientific way of doing this, other than trial and error? Jim

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• Purpose of Explicit Default Constructors

  - by Dennis Zickefoose

  I recently noticed a class in C++0x that calls for an explicit default constructor. However, I'm failing to come up with a scenario in which a default constructor can be called implicitly. It seems like a rather pointless specifier. I thought maybe it would disallow Class c; in favor of Class c = Class(); but that does not appear to be the case. Some relevant quotes from the C++0x FCD, since it is easier for me to navigate [similar text exists in C++03, if not in the same places] 12.3.1.3 [class.conv.ctor] A default constructor may be an explicit constructor; such a constructor will be used to perform default-initialization or value initialization (8.5). It goes on to provide an example of an explicit default constructor, but it simply mimics the example I provided above. 8.5.6 [decl.init] To default-initialize an object of type T means: — if T is a (possibly cv-qualified) class type (Clause 9), the default constructor for T is called (and the initialization is ill-formed if T has no accessible default constructor); 8.5.7 [decl.init] To value-initialize an object of type T means: — if T is a (possibly cv-qualified) class type (Clause 9) with a user-provided constructor (12.1), then the default constructor for T is called (and the initialization is ill-formed if T has no accessible default constructor); In both cases, the standard calls for the default constructor to be called. But that is what would happen if the default constructor were non-explicit. For completeness sake: 8.5.11 [decl.init] If no initializer is specified for an object, the object is default-initialized; From what I can tell, this just leaves conversion from no data. Which doesn't make sense. The best I can come up with would be the following: void function(Class c); int main() { function(); //implicitly convert from no parameter to a single parameter } But obviously that isn't the way C++ handles default arguments. What else is there that would make explicit Class(); behave differently from Class();? The specific example that generated this question was std::function [20.8.14.2 func.wrap.func]. It requires several converting constructors, none of which are marked explicit, but the default constructor is.

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• How does MySQL's ORDER BY RAND() work?

  - by Eugene

  Hi, I've been doing some research and testing on how to do fast random selection in MySQL. In the process I've faced some unexpected results and now I am not fully sure I know how ORDER BY RAND() really works. I always thought that when you do ORDER BY RAND() on the table, MySQL adds a new column to the table which is filled with random values, then it sorts data by that column and then e.g. you take the above value which got there randomly. I've done lots of googling and testing and finally found that the query Jay offers in his blog is indeed the fastest solution: SELECT * FROM Table T JOIN (SELECT CEIL(MAX(ID)*RAND()) AS ID FROM Table) AS x ON T.ID >= x.ID LIMIT 1; While common ORDER BY RAND() takes 30-40 seconds on my test table, his query does the work in 0.1 seconds. He explains how this functions in the blog so I'll just skip this and finally move to the odd thing. My table is a common table with a PRIMARY KEY id and other non-indexed stuff like username, age, etc. Here's the thing I am struggling to explain SELECT * FROM table ORDER BY RAND() LIMIT 1; /*30-40 seconds*/ SELECT id FROM table ORDER BY RAND() LIMIT 1; /*0.25 seconds*/ SELECT id, username FROM table ORDER BY RAND() LIMIT 1; /*90 seconds*/ I was sort of expecting to see approximately the same time for all three queries since I am always sorting on a single column. But for some reason this didn't happen. Please let me know if you any ideas about this. I have a project where I need to do fast ORDER BY RAND() and personally I would prefer to use SELECT id FROM table ORDER BY RAND() LIMIT 1; SELECT * FROM table WHERE id=ID_FROM_PREVIOUS_QUERY LIMIT 1; which, yes, is slower than Jay's method, however it is smaller and easier to understand. My queries are rather big ones with several JOINs and with WHERE clause and while Jay's method still works, the query grows really big and complex because I need to use all the JOINs and WHERE in the JOINed (called x in his query) sub request. Thanks for your time!

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• Fairness: Where can it be better handled?

  - by Srinivas Nayak

  Hi, I would like to share one of my practical experience with multiprogramming here. Yesterday I had written a multiprogram. Modifications to sharable resources were put under critical sections protected by P(mutex) and V(mutex) and those critical section code were put in a common library. The library will be used by concurrent applications (of my own). I had three applications that will use the common code from library and do their stuff independently. my library --------- work_on_shared_resource { P(mutex) get_shared_resource work_with_it V(mutex) } --------- my application ----------- application1 { *[ work_on_shared_resource do_something_else_non_ctitical ] } application2 { *[ work_on_shared_resource do_something_else_non_ctitical ] } application3 { *[ work_on_shared_resource ] } *[...] denote a loop. ------------ I had to run the applications on Linux OS. I had a thought in my mind, hanging over years, that, OS shall schedule all the processes running under him with all fairness. In other words, it will give all the processes, their pie of resource-usage equally well. When first two applications were put to work, they run perfectly well without deadlock. But when the third application started running, always the third one got the resources, but since it is not doing anything in its non-critical region, it gets the shared resource more often when other tasks are doing something else. So the other two applications were found almost totally halted. When the third application got terminated forcefully, the previous two applications resumed their work as before. I think, this is a case of starvation, first two applications had to starve. Now how can we ensure fairness? Now I started believing that OS scheduler is innocent and blind. It depends upon who won the race; he got the largest pie of CPU and resource. Shall we attempt to ensure fairness of resource users in the critical-section code in library? Or shall we leave it up to the applications to ensure fairness by being liberal, not greedy? To my knowledge, adding code to ensure fairness to the common library shall be an overwhelming task. On the other hand, believing on the applications will also never ensure 100% fairness. The application which does a very little task after working with shared resources shall win the race where as the application which does heavy processing after their work with shared resources shall always starve. What is the best practice in this case? Where we ensure fairness and how? Sincerely, Srinivas Nayak

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• List of Django model instance foreign keys losing consistency during state changes.

  - by Joshua

  I have model, Match, with two foreign keys: class Match(model.Model): winner = models.ForeignKey(Player) loser = models.ForeignKey(Player) When I loop over Match I find that each model instance uses a unique object for the foreign key. This ends up biting me because it introduces inconsistency, here is an example: >>> def print_elo(match_list): ... for match in match_list: ... print match.winner.id, match.winner.elo ... print match.loser.id, match.loser.elo ... >>> print_elo(teacher_match_list) 4 1192.0000000000 2 1192.0000000000 5 1208.0000000000 2 1192.0000000000 5 1208.0000000000 4 1192.0000000000 >>> teacher_match_list[0].winner.elo = 3000 >>> print_elo(teacher_match_list) 4 3000 # Object 4 2 1192.0000000000 5 1208.0000000000 2 1192.0000000000 5 1208.0000000000 4 1192.0000000000 # Object 4 >>> I solved this problem like so: def unify_refrences(match_list): """Makes each unique refrence to a model instance non-unique. In cases where multiple model instances are being used django creates a new object for each model instance, even if it that means creating the same instance twice. If one of these objects has its state changed any other object refrencing the same model instance will not be updated. This method ensure that state changes are seen. It makes sure that variables which hold objects pointing to the same model all hold the same object. Visually this means that a list of [var1, var2] whose internals look like so: var1 --> object1 --> model1 var2 --> object2 --> model1 Will result in the internals being changed so that: var1 --> object1 --> model1 var2 ------^ """ match_dict = {} for match in match_list: try: match.winner = match_dict[match.winner.id] except KeyError: match_dict[match.winner.id] = match.winner try: match.loser = match_dict[match.loser.id] except KeyError: match_dict[match.loser.id] = match.loser My question: Is there a way to solve the problem more elegantly through the use of QuerySets without needing to call save at any point? If not, I'd like to make the solution more generic: how can you get a list of the foreign keys on a model instance or do you have a better generic solution to my problem? Please correct me if you think I don't understand why this is happening.

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• How should I model the database for this problem? And which ORM can handle it?

  - by Kristof Claes

  I need to build some sort of a custom CMS for a client of ours. These are some of the functional requirements: Must be able to manage the list of Pages in the site Each Page can contain a number of ColumnGroups A ColumnGroup is nothing more than a list of Columns in a certain ColumnGroupLayout. For example: "one column taking up the entire width of the page", "two columns each taking up half of the width", ... Each Column can contain a number ContentBlocks Examples of a ContentBlock are: TextBlock, NewsBlock, PictureBlock, ... ContentBlocks can be given a certain sorting within a Column A ContentBlock can be put in different Columns so that content can be reused without having to be duplicated. My first quick draft of how this could look like in C# code (we're using ASP.NET 4.0 to develop the CMS) can be found at the bottom of my question. One of the technical requirements is that it must be as easy as possible to add new types of ContentBlocks to the CMS. So I would like model everything as flexible as possible. Unfortunately, I'm already stuck at trying to figure out how the database should look like. One of the problems I'm having has to do with sorting different types of ContentBlocks in a Column. I guess each type of ContentBlock (like TextBlock, NewsBlock, PictureBlock, ...) should have it's own table in the database because each has it's own different fields. A TextBlock might only have a field called Text whereas a NewsBlock might have fields for the Text, the Summary, the PublicationDate, ... Since one Column can have ContentBlocks located in different tables, I guess I'll have to create a many-to-many association for each type of ContentBlock. For example: ColumnTextBlocks, ColumnNewsBlocks and ColumnPictureBlocks. The problem I have with this setup is the sorting of the different ContentBlocks in a column. This could be something like this: TextBlock NewsBlock TextBlock TextBlock PictureBlock Where do I store the sorting number? If I store them in the associaton tables, I'll have to update a lot of tables when changing the sorting order of ContentBlocks in a Column. Is this a good approach to the problem? Basically, my question is: What is the best way to model this keeping in mind that it should be easy to add new types of ContentBlocks? My next question is: What ORM can deal with that kind of modeling? To be honest, we are ORM-virgins at work. I have been reading a bit about Linq-to-SQL and NHibernate, but we have no experience with them. Because of the IList in the Column class (see code below) I think we can rule out Linq-to-SQL, right? Can NHibernate handle the mapping of data from many different tables to one IList? Also keep in mind that this is just a very small portion of the domain. Other parts are Users belonging to a certain UserGroup having certain Permissions on Pages, ColumnGroups, Columns and ContentBlocks. The code (just a quick first draft): public class Page { public int PageID { get; set; } public string Title { get; set; } public string Description { get; set; } public string Keywords { get; set; } public IList<ColumnGroup> ColumnGroups { get; set; } } public class ColumnGroup { public enum ColumnGroupLayout { OneColumn, HalfHalf, NarrowWide, WideNarrow } public int ColumnGroupID { get; set; } public ColumnGroupLayout Layout { get; set; } public IList<Column> Columns { get; set; } } public class Column { public int ColumnID { get; set; } public IList<IContentBlock> ContentBlocks { get; set; } } public interface IContentBlock { string GetSummary(); } public class TextBlock : IContentBlock { public string GetSummary() { return "I am a piece of text."; } } public class NewsBlock : IContentBlock { public string GetSummary() { return "I am a news item."; } }

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• Android: dynamically setting links to text in strings.xml

  - by Martyn

  I'm trying to make an app with localisation built in, but I want a way that I can create a web link within the text, the URL being defined elsewhere (for ease of maintenance). So, I have my links in res/values/strings.xml: <?xml version="1.0" encoding="utf-8"?> <resources> ... <string name="link1">http://some.link.com</string> <string name="link2">http://some.link2.com</string> </resources> and my localised text in res/values-en-rGB/strings.xml <?xml version="1.0" encoding="utf-8"?> <resources> ... <string name="sampleText">Sample text\nMore text and link1\nMore text and link2.</string> </resources> I've not tested this bit, but from the localization section of developer.android.com it says that this approach to reducing content duplication should work, although I'm not sure what folder I should put Italian, for example. Would it be in 'res/values-it-rIT/strings.xml'? Lets assume that I have various other languages too. I'm looking for a way of taking the base localised 'sampleText' and inserting my html links in, and getting them to work when clicked on. I've tried two approaches so far: 1, Putting some formatting in the 'sampleText' (%s): <string name="sampleText">Sample text\nMore text and <a href="%s">link1</a>\nMore text and <a href="%s">link2</a>.</string> and then processing the text like this: TextView tv = (TextView) findViewById(R.id.textHolder); tv.setText(getResources().getString(R.string.sampleText, getResources().getString(R.string.link1), getResources().getString(R.string.link2))); But this didn't work when I click on the link, even though the link text is being put in to the correct places. 2, I tried to use Linkify but the regular expression route may be difficult as I'm looking at supporting non-Latin based languages. I tried to put a custom xml tag around the link text and then do something like this: Pattern wordMatcher = Pattern.compile("<span1>.*</span1>"); String viewURL = "content://" + getResources().getString(R.string.someLink); Linkify.addLinks(tv, wordMatcher , viewURL ); But this didn't work either. So, I'd like to know if there's a way of dynamically adding multiple URLs to different sections of the same text which will link to web content? Thank you, Martyn

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• What is the best way to archive data in a relational database?

  - by GenericTypeTea

  I have a bit of an issue with a particular aspect of a program I'm working on. I need the ability to archive (fix) a table so that a change anywhere in the system will not affect the results it returns. This is the basic structure of what I need to fix: Recipe --> Recipe (as sub recipe) Recipe --> Ingredients So, if I fix a Recipe, I need to ensure all the sub recipes (including all the sub recipes sub recipes and so forth) are fixed and all its ingredients are fixed. The problem is that the sub recipe and ingredients still need to be modifiable as they are used by other recipes that are not fixed. I came up with a solution whereby I serialize (with protobuf-net) a master object that deals with the recipe and all the sub recipes and ingredients and save the archive data to a table like follows: Archive{ ReferenceId, (i.e. RecipeId) ReferenceTypeId, (i.e. Recipe) ArchiveData varbinary(max) } Now, this works great and is almost perfect... however I totally forgot (I'd love to blame the agile development mentally, however this was just short sighted) that this information needs to be reported on. As far as I'm aware I can't think how I could inflate the serialized data back into my Recipe Object and use it in a Report. I'm using the standard SQL 2005 report services at the moment. Alternatively, I guess I could do the following: Duplicate every table and tag the word "Archive" on the end of the table name. This would then give me an area of specific archive data... but ignoring my simplified example, there'd actually be about 15 tables duplicated. Add a nullable, non-foreign key property called "CopiedFromId" to every table that contains fixed data and duplicate every record that the recipe (and all it's sub recipes and all their sub recipes) touches. Create some sort of denormalised structure that could be restored from at a later date to the original, unfixed recipe. Although I think this would be like option 1 and involve a lot of extra tables. Anyway, I'm at a total loss and do not like any of the ideas particularly. Can anyone please advise the best course of action? EDIT: Or 4) Create tables specific to what the report requires and populate them with the data when the user clicks the report button? This would cause about 4 extra tables for the report in question.

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• XmlDataProvider and XPath bindings don't allow default namespace of XML data?

  - by Andy Dent

  I am struggling to work out how to use default namespaces with XmlDataProvider and XPath bindings. There's an ugly answer using local-name <Binding XPath="*[local-name()='Name']" /> but that is not acceptable to the client who wants this XAML to be highly maintainable. The fallback is to force them to use non-default namespaces in the report XML but that is an undesirable solution. The XML report file looks like the following. It will only work if I remove xmlns="http://www.acme.com/xml/schemas/report so there is no default namespace. <?xml version="1.0" encoding="utf-8"?> <?xml-stylesheet type='text/xsl' href='PreviewReportImages.xsl'?> <Report xsl:schemaLocation="http://www.acme.com/xml/schemas/report BlahReport.xsd" xmlns:xsl="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.acme.com/xml/schemas/report"> <Service>Muncher</Service> <Analysis> <Date>27 Apr 2010</Date> <Time>0:09</Time> <Authoriser>Service Centre Manager</Authoriser> Which I am presenting in a window with XAML: <Window x:Class="AcmeTest.ReportPreview" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="ReportPreview" Height="300" Width="300" > <Window.Resources> <XmlDataProvider x:Key="Data"/> </Window.Resources> <StackPanel Orientation="Vertical" DataContext="{Binding Source={StaticResource Data}, XPath=Report}"> <TextBlock Text="{Binding XPath=Service}"/> </StackPanel> </Window> with code-behind used to load an XmlDocument into the XmlDataProvider (seems the only way to have loading from a file or object varying at runtime). public partial class ReportPreview : Window { private void InitXmlProvider(XmlDocument doc) { XmlDataProvider xd = (XmlDataProvider)Resources["Data"]; xd.Document = doc; } public ReportPreview(XmlDocument doc) { InitializeComponent(); InitXmlProvider(doc); } public ReportPreview(String reportPath) { InitializeComponent(); var doc = new XmlDocument(); doc.Load(reportPath); InitXmlProvider(doc); } }

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• Is it too early to start designing for Task Parallel Library?

  - by Joe Erickson

  I have been following the development of the .NET Task Parallel Library (TPL) with great interest since Microsoft first announced it. There is no doubt in my mind that we will eventually take advantage of TPL. What I am questioning is whether it makes sense to start taking advantage of TPL when Visual Studio 2010 and .NET 4.0 are released, or whether it makes sense to wait a while longer. Why Start Now? The .NET 4.0 Task Parallel Library appears to be well designed and some relatively simple tests demonstrate that it works well on today's multi-core CPUs. I have been very interested in the potential advantages of using multiple lightweight threads to speed up our software since buying my first quad processor Dell Poweredge 6400 about seven years ago. Experiments at that time indicated that it was not worth the effort, which I attributed largely to the overhead of moving data between each CPU's cache (there was no shared cache back then) and RAM. Competitive advantage - some of our customers can never get enough performance and there is no doubt that we can build a faster product using TPL today. It sounds fun. Yes, I realize that some developers would rather poke themselves in the eye with a sharp stick, but we really enjoy maximizing performance. Why Wait? Are today's Intel Nehalem CPUs representative of where we are going as multi-core support matures? You can purchase a Nehalem CPU with 4 cores which share a single level 3 cache today, and most likely a 6 core CPU sharing a single level 3 cache by the time Visual Studio 2010 / .NET 4.0 are released. Obviously, the number of cores will go up over time, but what about the architecture? As the number of cores goes up, will they still share a cache? One issue with Nehalem is the fact that, even though there is a very fast interconnect between the cores, they have non-uniform memory access (NUMA) which can lead to lower performance and less predictable results. Will future multi-core architectures be able to do away with NUMA? Similarly, will the .NET Task Parallel Library change as it matures, requiring modifications to code to fully take advantage of it? Limitations Our core engine is 100% C# and has to run without full trust, so we are limited to using .NET APIs.

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• Annoying Captcha >> How to programm a form that can SMELL difference between human and robot?

  - by Sam

  Hi folks. On the comment of my old form needing a CAPTHA, I felt I share my problem, perhaps you recognize it and find its time we had better solutions: FACTUAL PROBLEM I know most of my clients (typical age= 40~60) hate CAPTCHA things. Now, I myself always feel like a robot, when I have to sueeze my eyes and fill in the strange letters from the Capcha... Sometimes I fail! Go back etc. Turnoff. I mean comon its 2011, shouldnt the forms have better A.I. by now? MY NEW IDEA (please dont laugh) Ive thought about it and this is my idea's to tell difference between human and robot: My idea is to give credibility points. 100 points = human 0% = robot. require real human mouse movements require mousemovements that dont follow any mathematical pattern require non-instantaneous reading delays, between load and first input in form when typing in form, delays are measured between letters and words approve as human when typical human behaviour measured (deleting, rephrasing etc) dont allow instant pasting or all fields give points for real keyboard pressures retract points for credibility when hyperlinks in form Test wether fake email field (invisible by human) is populated (suggested by Tomalak) when more than 75% human cretibility, allow to be sent without captcha when less than 25% human crecibility, force captcha puzzle to be sure Could we write a A.I. PHP that replaces the human-annoying capthas, meanwhile stopping most spamservers filing in the data? Not only for the fun of it, but also actually to provide a 99% better alternative than CAPTHCA's. Imagine the userfriendlyness of your forms! Your site distinguishing itself from others, showing your audience your sites KNOWS the difference between a robot and a human. Imagine the advangage. I am trying to capture the essense of that distinguishing edge. PROGRAMMING QUESTION: 1) Are such things possible to programm? 2) If so how would you start such programm? 3) Are there already very good working solutions available elsewhere? 4) If it isn't so hard, your are welcome to share your answer/solutions below. 5) upon completion of hints and new ideas, could this page be the start of a new AI captcha, OR should I forget about it and just go with the flow, forget about the whole AI dream, and use captcha like everyone else.

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• GCC: Simple inheritance test fails

  - by knight666

  I'm building an open source 2D game engine called YoghurtGum. Right now I'm working on the Android port, using the NDK provided by Google. I was going mad because of the errors I was getting in my application, so I made a simple test program: class Base { public: Base() { } virtual ~Base() { } }; // class Base class Vehicle : virtual public Base { public: Vehicle() : Base() { } ~Vehicle() { } }; // class Vehicle class Car : public Vehicle { public: Car() : Base(), Vehicle() { } ~Car() { } }; // class Car int main(int a_Data, char** argv) { Car* stupid = new Car(); return 0; } Seems easy enough, right? Here's how I compile it, which is the same way I compile the rest of my code: /home/oem/android-ndk-r3/build/prebuilt/linux-x86/arm-eabi-4.4.0/bin/arm-eabi-g++ -g -std=c99 -Wall -Werror -O2 -w -shared -fshort-enums -I ../../YoghurtGum/src/GLES -I ../../YoghurtGum/src -I /home/oem/android-ndk-r3/build/platforms/android-5/arch-arm/usr/include -c src/Inheritance.cpp -o intermediate/Inheritance.o (Line breaks are added for clarity). This compiles fine. But then we get to the linker: /home/oem/android-ndk-r3/build/prebuilt/linux-x86/arm-eabi-4.4.0/bin/arm-eabi-gcc -lstdc++ -Wl, --entry=main, -rpath-link=/system/lib, -rpath-link=/home/oem/android-ndk-r3/build/platforms/android-5/arch-arm/usr/lib, -dynamic-linker=/system/bin/linker, -L/home/oem/android-ndk-r3/build/prebuilt/linux-x86/arm-eabi-4.4.0/lib/gcc/arm-eabi/4.4.0, -L/home/oem/android-ndk-r3/build/platforms/android-5/arch-arm/usr/lib, -rpath=../../YoghurtGum/lib/GLES -nostdlib -lm -lc -lGLESv1_CM -z /home/oem/android-ndk-r3/build/platforms/android-5/arch-arm/usr/lib/crtbegin_dynamic.o /home/oem/android-ndk-r3/build/platforms/android-5/arch-arm/usr/lib/crtend_android.o intermediate/Inheritance.o ../../YoghurtGum/bin/YoghurtGum.a -o bin/Galaxians.android As you can probably tell, there's a lot of cruft in there that isn't really needed. That's because it doesn't work. It fails with the following errors: intermediate/Inheritance.o:(.rodata._ZTI3Car[typeinfo for Car]+0x0): undefined reference to `vtable for __cxxabiv1::__si_class_type_info' intermediate/Inheritance.o:(.rodata._ZTI7Vehicle[typeinfo for Vehicle]+0x0): undefined reference to `vtable for __cxxabiv1::__vmi_class_type_info' intermediate/Inheritance.o:(.rodata._ZTI4Base[typeinfo for Base]+0x0): undefined reference to `vtable for __cxxabiv1::__class_type_info' collect2: ld returned 1 exit status make: *** [bin/Galaxians.android] Fout 1 These are the same errors I get from my actual application. If someone could explain to me where I went wrong in my test or what option or I forgot in my linker, I would be very, extremely grateful. Thanks in advance. UPDATE: When I make my destructors non-inlined, I get new and more exciting link errors: intermediate/Inheritance.o:(.rodata+0x78): undefined reference to `vtable for __cxxabiv1::__si_class_type_info' intermediate/Inheritance.o:(.rodata+0x90): undefined reference to `vtable for __cxxabiv1::__vmi_class_type_info' intermediate/Inheritance.o:(.rodata+0xb0): undefined reference to `vtable for __cxxabiv1::__class_type_info' collect2: ld returned 1 exit status make: *** [bin/Galaxians.android] Fout 1

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• Avoiding circular project/assembly references in Visual Studio with statically typed dependency conf

  - by svnpttrssn

  First, I want to say that I am not interested in debating about any non-helpful "answers" to my question, with suggestions to putting everything in one assembly, i.e. there is no need for anyone to provide webpages such as the page titled with "Separate Assemblies != Loose Coupling". Now, my question is if it somehow (maybe with some Visual Studio configuration to allow for circular project dependencies?) is possible to use one project/assembly (I am here calling it the "ServiceLocator" assembly) for retrieving concrete implementation classes, (e.g. with StructureMap) which can be referred to from other projects, while it of course is also necessary for the the ServiceLocator itself to refer to other projects with the interfaces and the implementations ? Visual Studio project example, illustrating the kind of dependency structure I am talking about: http://img10.imageshack.us/img10/8838/testingdependencyinject.png Please note in the above picture, the problem is how to let the classes in "ApplicationLayerServiceImplementations" retrieve and instantiate classes that implement the interfaces in "DomainLayerServiceInterfaces". The goal is here to not refer directly to the classes in "DomainLayerServiceImplementations", but rather to try using the project "ServiceLocator" to retrieve such classes, but then the circular dependency problem occurrs... For example, a "UserInterfaceLayer" project/assembly might contain this kind of code: ContainerBootstrapper.BootstrapStructureMap(); // located in "ServiceLocator" project/assembly MyDomainLayerInterface myDomainLayerInterface = ObjectFactory.GetInstance<MyDomainLayerInterface>(); // refering to project/assembly "DomainLayerServiceInterfaces" myDomainLayerInterface.MyDomainLayerMethod(); MyApplicationLayerInterface myApplicationLayerInterface = ObjectFactory.GetInstance<MyApplicationLayerInterface>(); // refering to project/assembly "ApplicationLayerServiceInterfaces" myApplicationLayerInterface.MyApplicationLayerMethod(); The above code do not refer to the implementation projects/assemblies ApplicationLayerServiceImplementations and DomainLayerServiceImplementations, which contain this kind of code: public class MyApplicationLayerImplementation : MyApplicationLayerInterface and public class MyDomainLayerImplementation : MyDomainLayerInterface The "ServiceLocator" project/assembly might contain this code: using ApplicationLayerServiceImplementations; using ApplicationLayerServiceInterfaces; using DomainLayerServiceImplementations; using DomainLayerServiceInterfaces; using StructureMap; namespace ServiceLocator { public static class ContainerBootstrapper { public static void BootstrapStructureMap() { ObjectFactory.Initialize(x => { // The two interfaces and the two implementations below are located in four different Visual Studio projects x.ForRequestedType<MyDomainLayerInterface>().TheDefaultIsConcreteType<MyDomainLayerImplementation>(); x.ForRequestedType<MyApplicationLayerInterface>().TheDefaultIsConcreteType<MyApplicationLayerImplementation>(); }); } } } So far, no problem, but the problem occurs when I want to let the class "MyApplicationLayerImplementation" in the project/assembly "ApplicationLayerServiceImplementations" use the "ServiceLocator" project/assembly for retrieving an implementation of "MyDomainLayerInterface". When I try to do that, i.e. add a reference from "MyApplicationLayerImplementation" to "ServiceLocator", then Visual Studio complains about circular dependencies between projects. Is there any nice solution to this problem, which does not imply using refactoring-unfriendly string based xml-configuration which breaks whenever an interface or class or its namespace is renamed ? / Sven

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