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• Windows 7 Machine Makes Router Drop -All- Wireless Connections

  - by Hammer Bro.

  Some background: My home network consists of my Desktop, a two-month old Windows 7 (x64) machine which is online most frequently (N-spec), as well as three other Windows XP laptops (all G) that only connect every now and then (one for work, one for Netflix, and the other for infrequent regular laptop uses). I used to have a Belkin F5D8236-4 wireless router, and everything worked great. A week ago, however, I found out that the Belkin absolutely in no way would establish a VPN connection, something that has become important for work. So I bought a Netgear WNR3500v2/U/L. The wireless was acting a little sketchy at first for just the Windows 7 machine, but I thought it had something to do with 802.11N and I was in a hurry so I just fished up an ethernet cable and disabled the computer's wireless. It has now become apparent, though, that whenever the Windows 7 machine is connected to the router, all wireless connections become unstable. I was using my work laptop for a solid six hours today with no trouble, having multiple SSH connections open over VPN and streaming internet radio in the background. Then, within two minutes of turning on this Windows 7 box, I had lost all connectivity over the wireless. And I was two feet away from the router. The same sort of thing happens on all of the other laptops -- Netflix can be playing stuff all weekend, but if I come up here and do things on this (W7) computer, the streaming will be dead within ten minutes. So here are my basic observations: If the Windows 7 machine is off, then all connections will have a Signal Strength of Very Good or Excellent and a Speed of 48-54 Mbps for an indefinite amount of time. Shortly after the Windows 7 machine is turned on, all wireless connections will experience a consistent decline in Speed down to 1.0 Mbps, eventually losing their connection entirely. These machines will continue to maintain 70% signal strength, as observed by themselves and router. Once dropped, a wireless connection will have difficulty reconnecting. And, if a connection manages to become established, it will quickly drop off again. The Windows 7 machine itself will continue to function just fine if it's using a wired connection, although it will experience these same issues over the wireless. All of the drivers and firmwares are up to date, and this happened both with the stock Netgear firmware as well as the (current) DD-WRT. What I've tried: Making sure each computer is being assigned a distinct IP. (They are.) Disabling UPnP and Stateful Packet Inspection on the router. Disabling Network Sharing, SSDP Discovery, TCP/IP NetBios Helper and Computer Browser services on the Windows 7 machine. Disabling QoS Packet Scheduler, IPv6, and Link Layer Topology Discovery options on my ethernet controller (leaving only Client for Microsoft Networks, File and Printer Sharing, and IPv4 enabled). What I think: It seems awfully similar to the problems discussed in detail at http://social.msdn.microsoft.com/Forums/en/wsk/thread/1064e397-9d9b-4ae2-bc8e-c8798e591915 (which was both the most relevant and concrete information I could dig up on the internet). I still think that something the Windows 7 IP stack (or just Operating System itself) is doing is giving the router fits. However, I could be wrong, because I have two key differences. One is that most instances of this problem are reported as the entire router dying or restarting, and mine still works just fine over the wired connection. The other is that it's a new router, tested with both the factory firmware and the (I assume) well-maintained DD-WRT project. Even if Windows 7 is still secretly sending IPv6 packets or the TCP Window Scaling implementation that I hear Vista caused some trouble with (even though I've tried my best to disable anything fancy), this router should support those functions. I don't want to get a new or a replacement router unless someone can convince me that this is a defective unit. But the problem seems too specific and predictable by my instincts to be a hardware hiccup. And I don't want to deal with the inevitable problems that always seem to take half a day to resolve when getting a new router, since I'm frantically working (including tomorrow) to complete a project by next week's deadline. Plus, I think in the worst case scenario, I could keep this router connected directly to the modem, disable its wireless entirely, and connect the old Belkin to it directly. That should allow me to still use VPN (although I'll have to plug my work laptop directly into that router), and then maintain wireless connections for all of the other computers. But that feels so wrong to me. Anyone have any ideas what the cause and possible solution could be? Clarifications: The Windows 7 machine is directly connected via an ethernet cable to the router for everything above. But while it is online, all other computers' wireless connections become unusable. It is not an issue of signal strength or interference -- no other devices within scanning range are using Channel 1, and the problem will affect computers that are literally feet away from the router with 95% signal strength.

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• Hyper-V File Server Clustering - at my wit’s end

  - by René Kåbis

  I am at my wit’s end with File Server clustering under Hyper-V. I am hoping that someone might be able to help me figure out this Gordian Knot of a technology that seems to have dead ends (like forcing cluster VMs to use iSCSI drives where normally-attached VHDX drives could suffice) where logic and reason would normally provide a logical solution. My hardware: I will be running three servers (in the end), but right now everything is taking place on one server. One of the secondary servers will exist purely as a witness/quorum, and another slightly more powerful one will be acting as an emergency backup (with additional storage, just not redundant) to hold the secondary AD VM and the other halves of a set of clustered VMs: the SQL VM and the file system VM. Please note, these each are the depreciated nodes of a cluster, the main nodes will be on the most powerful first machine. My heavy lifter is a machine that also contains all of the truly redundant storage on the network. If this gives anyone the heebie-geebies, too bad. It has a 6TB (usable) RAID-10 array, and will (in the end) hold the primary nodes of both aforementioned clusters, but is right now holding all VMs. This is, right now: DC01, DC02, SQL01, SQL02, FS01 & FS02. Eventually, I will be adding additional VMs to handle Exchange, Sharepoint and Lync, but only to this main server (the secondary server won't be able to handle more than three or four VMs, so why burden it? The AD, SQL & FS VMs are the most critical for the business). If anyone is now saying, “wait, what about a SAN or a NAS for the file servers?”, well too bad. What exists on the main machine is what I have to deal with. I followed these instructions, but I seem to be unable to get things to work. In order to make the file server truly redundant, I cannot trust any one machine to hold the only data store on the network. Therefore, I have created a set of iSCSI drives on the VM-host of the main machine, and attached one to each file server VM. The end result is that I want my FS01 to sit on the heavy lifter, along with its iSCSI “drive”, and FS02 will sit on the secondary machine with its own iSCSI “drive” there as well. That is, neither iSCSI drive will end up sitting on the same machine as the other. As such, the clustered FS will utterly duplicate the contents of the iSCSI drives between each other, so that if one physical machine (or the FS VM) goes toes-up, the other has got a full copy of the data on its own iSCSI drive. My problem occurs when I try to apply the file server role within the failover cluster manager. Actually, it is even before that -- it occurs when adding the disks. Since I have added each disk preferentially to a specific VM (by limiting the initiator by DNS hostname, and by adding two-way CHAP authentication), this forces each VM to be in control of its own iSCSI disk. However, when I try to add the disks to the Disks section of Storage within Failover Cluster Manager, the entire process fails for a random disk of the pair. That is, one will get online, but the other will remain offline because it does not have the correct “owner node”. I mean, really -- WTF? Of course it doesn’t have the right owner node, both drives are showing the same node name!! I cannot seem to have one drive show up with one node name as owner, and the other drive show up with the other node name as owner. And because both drives are not “online”, I cannot create a pool to apply to a cluster role. Talk about getting stuck between a rock and a hard place! I’ve got more to add, but my work is closing for the day and I have to wrap things up. I will try to add more tomorrow morning when I get in. My main objective is to have a file server VM on each machine, the storage on each machine, but a transparent failover in case one physical machine fails. Essentially, a failover FS that doesn’t care which machine fails -- the storage contents are replicated equally on each machine. Am I even heading in the right direction?

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• Question about how to use strong typed dataset in N-tier application for .NET

  - by sb

  Hello All, I need some expert advice on strong typed data sets in ADO.NET that are generated by the Visual Studio. Here are the details. Thank you in advance. I want to write a N-tier application where Presentation layer is in C#/windows forms, Business Layer is a Web service and Data Access Layer is SQL db. So, I used Visual Studio 2005 for this and created 3 projects in a solution. project 1 is the Data access layer. In this I have used visual studio data set generator to create a strong typed data set and table adapter (to test I created this on the customers table in northwind). The data set is called NorthWindDataSet and the table inside is CustomersTable. project 2 has the web service which exposes only 1 method which is GetCustomersDataSet. This uses the project1 library's table adapter to fill the data set and return it to the caller. To be able to use the NorthWindDataSet and table adapter, I added a reference to the project 1. project 3 is a win forms app and this uses the web service as a reference and calls that service to get the data set. In the process of building this application, in the PL, I added a reference to the DataSet generated above in the project 1 and in form's load I call the web service and assign the received DataSet from the web service to this dataset. But I get the error: "Cannot implicitly convert type 'PL.WebServiceLayerReference.NorthwindDataSet' to 'BL.NorthwindDataSet' e:\My Documents\Visual Studio 2008\Projects\DataSetWebServiceExample\PL\Form1.cs". Both the data sets are same but because I added references from different locations, I am getting the above error I think. So, what I did was I added a reference to project 1 (which defines the data set) to project 3 (the UI) and used the web service to get the DataSet and assing to the right type, now when the project 3 (which has the web form) runs, I get the below runtime exception. "System.InvalidOperationException: There is an error in XML document (1, 5058). --- System.Xml.Schema.XmlSchemaException: Multiple definition of element 'http://tempuri.org/NorthwindDataSet.xsd:Customers' causes the content model to become ambiguous. A content model must be formed such that during validation of an element information item sequence, the particle contained directly, indirectly or implicitly therein with which to attempt to validate each item in the sequence in turn can be uniquely determined without examining the content or attributes of that item, and without any information about the items in the remainder of the sequence." I think this might be because of some cross referenceing errors. My question is, is there a way to use the visual studio generated DataSets in such a way that I can use the same DataSet in all layers (for reuse) but separate the Table Adapter logic to the Data Access Layer so that the front end is abstracted from all this by the web service? If I have hand write the code I loose the goodness the data set generator gives and also if there are columns added later I need to add it by hand etc so I want to use the visual studio wizard as much as possible. thanks for any help on this. sb

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• Architecture for a business objects / database access layer

  - by gregmac

  For various reasons, we are writing a new business objects/data storage library. One of the requirements of this layer is to separate the logic of the business rules, and the actual data storage layer. It is possible to have multiple data storage layers that implement access to the same object - for example, a main "database" data storage source that implements most objects, and another "ldap" source that implements a User object. In this scenario, User can optionally come from an LDAP source, perhaps with slightly different functionality (eg, not possible to save/update the User object), but otherwise it is used by the application the same way. Another data storage type might be a web service, or an external database. There are two main ways we are looking at implementing this, and me and a co-worker disagree on a fundamental level which is correct. I'd like some advice on which one is the best to use. I'll try to keep my descriptions of each as neutral as possible, as I'm looking for some objective view points here. Business objects are base classes, and data storage objects inherit business objects. Client code deals with data storage objects. In this case, common business rules are inherited by each data storage object, and it is the data storage objects that are directly used by the client code. This has the implication that client code determines which data storage method to use for a given object, because it has to explicitly declare an instance to that type of object. Client code needs to explicitly know connection information for each data storage type it is using. If a data storage layer implements different functionality for a given object, client code explicitly knows about it at compile time because the object looks different. If the data storage method is changed, client code has to be updated. Business objects encapsulate data storage objects. In this case, business objects are directly used by client application. Client application passes along base connection information to business layer. Decision about which data storage method a given object uses is made by business object code. Connection information would be a chunk of data taken from a config file (client app does not really know/care about details of it), which may be a single connection string for a database, or several pieces connection strings for various data storage types. Additional data storage connection types could also be read from another spot - eg, a configuration table in a database that specifies URLs to various web services. The benefit here is that if a new data storage method is added to an existing object, a configuration setting can be set at runtime to determine which method to use, and it is completely transparent to the client applications. Client apps do not need to be modified if data storage method for a given object changes. Business objects are base classes, data source objects inherit from business objects. Client code deals primarily with base classes. This is similar to the first method, but client code declares variables of the base business object types, and Load()/Create()/etc static methods on the business objects return the appropriate data source-typed objects. The architecture of this solution is similar to the first method, but the main difference is the decision about which data storage object to use for a given business object is made by the business layer, not the client code. I know there are already existing ORM libraries that provide some of this functionality, but please discount those for now (there is the possibility that a data storage layer is implemented with one of these ORM libraries) - also note I'm deliberately not telling you what language is being used here, other than that it is strongly typed. I'm looking for some general advice here on which method is better to use (or feel free to suggest something else), and why.

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• Resons why I'm using php rather then asp.net [closed]

  - by spirytus

  I have basic idea of how asp .Net works, but finds all framework hard to use if you are a newbie. I found compiling, web applications vs websites and all that stuff you should know to program in asp .net a bit tedious and so personally I go with php to create small, to medium applications for my clients. There are couple of reasons for it: php is easy scripting language, top to bottom and you done. You still can create objects, classes and if you have idea of MVC its fairly easy to create basic structure yourself so you can keep you presentation layer "relatively" clean. Although I find myself still mixing basic logic in my view's, I am trying to stick to booleans, and for each loops. ASP .net keeps it cleaner as far as I know and I agree that this is great. Heaps of free stuff for php and lots of help everywhere Although choice of IDE's for php is very limited, I still don't have to be stuck with VisualStudio. Lets be honest.. you can program in whatever you like but does anyone uses anything else other than VS? For basic applications I create, Visual Studio doesn't come even close to notepad :) / phpEdit (or similar) combination. It lacks of many features I constantly use, although armies of developers are using it and it must be for good reason. Personally not a big fan of VS though. Being on the market for that long should make editing much easier. I know .Net comes with awesome set of controls, validators etc. which is truly awesome. For me the problem starts if I want my validator to behave slightly different way and lets say fade in/out error messages. I know its possible to extend it behavior, plug into lifecycle and output different JS to the client and so on. I just never see it happen in places I work, and honestly, I don't even think most of .net developers I worked with during last couple of years would know how to do that. In php I have to grab some plugin for jQuery and use it for validation, which is fairly easy task once you had done it before. Again I'm sure its easy for .net gurus, but for newbie like me its almost impossible. I found that many asp .net programmers are very limited in what they are able to do and basically whack together .net applications using same lame set of controls, not even bothering in looking into how it works and what if? Now I don't want to anger anyone :) I know there is huge number of excellent .Net developers who know their stuff and are able to extend controls and do all that magic in no time. I found it a bit annoying though that many of them stick to what is provided without even trying to make it better. Nothing against .net here, just a thought really :) I remember when asp.net came out the idea was that front-end people will not be able to screw anything up and do their fron-end stuff without worrying what happens behind. Now its never that easy and I always tend to get server side people to fix this and that during development. Things like ID's assigned to controls can very easily make your application break and if someone is pure HTML guy using VS its easy to break something. Thats my thoughs on php and .net and reasons why for my work I go with php. I know that once learned asp .net is awesome technology and summing all up php doesn't even come close to it. For someone like me however, individually developing small basic applications for clients, php seems to work much better. Please let me know your thoughts on the above :)

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• TwoWay Binding With ItemsControl

  - by Andrew

  I'm trying to write a user control that has an ItemsControl, the ItemsTemplate of which contains a TextBox that will allow for TwoWay binding. However, I must be making a mistake somewhere in my code, because the binding only appears to work as if Mode=OneWay. This is a pretty simplified excerpt from my project, but it still contains the problem: <UserControl x:Class="ItemsControlTest.UserControl1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Height="300" Width="300"> <Grid> <StackPanel> <ItemsControl ItemsSource="{Binding Path=.}" x:Name="myItemsControl"> <ItemsControl.ItemTemplate> <DataTemplate> <TextBox Text="{Binding Mode=TwoWay, UpdateSourceTrigger=LostFocus, Path=.}" /> </DataTemplate> </ItemsControl.ItemTemplate> </ItemsControl> <Button Click="Button_Click" Content="Click Here To Change Focus From ItemsControl" /> </StackPanel> </Grid> </UserControl> Here's the code behind for the above control: using System; using System.Windows; using System.Windows.Controls; using System.Collections.ObjectModel; namespace ItemsControlTest { /// <summary> /// Interaction logic for UserControl1.xaml /// </summary> public partial class UserControl1 : UserControl { public ObservableCollection<string> MyCollection { get { return (ObservableCollection<string>)GetValue(MyCollectionProperty); } set { SetValue(MyCollectionProperty, value); } } // Using a DependencyProperty as the backing store for MyCollection. This enables animation, styling, binding, etc... public static readonly DependencyProperty MyCollectionProperty = DependencyProperty.Register("MyCollection", typeof(ObservableCollection<string>), typeof(UserControl1), new UIPropertyMetadata(new ObservableCollection<string>())); public UserControl1() { for (int i = 0; i < 6; i++) MyCollection.Add("String " + i.ToString()); InitializeComponent(); myItemsControl.DataContext = this.MyCollection; } private void Button_Click(object sender, RoutedEventArgs e) { // Insert a string after the third element of MyCollection MyCollection.Insert(3, "Inserted Item"); // Display contents of MyCollection in a MessageBox string str = ""; foreach (string s in MyCollection) str += s + Environment.NewLine; MessageBox.Show(str); } } } And finally, here's the xaml for the main window: <Window x:Class="ItemsControlTest.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:src="clr-namespace:ItemsControlTest" Title="Window1" Height="300" Width="300"> <Grid> <src:UserControl1 /> </Grid> </Window> Well, that's everything. I'm not sure why editing the TextBox.Text properties in the window does not seem to update the source property for the binding in the code behind, namely MyCollection. Clicking on the button pretty much causes the problem to stare me in the face;) Please help me understand where I'm going wrong. Thanx! Andrew

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• non-static variable cannot be referenced from a static context (java)

  - by Greg

  I ask that you ignore all logic.. i was taught poorly at first and so i still dont understand everything about static crap and its killing me. My error is with every single variable that i declare then try to use later inside my methods... i get the non-static variable cannot~~ error I can simply put all the rough coding of my methods inside my cases, and it works but then i cannot use recursion... What i really need is someone to help on the syntax and point me on the right direction of how to have my methods recognize my variables at the top... like compareCount etc thanks public class MyProgram7 { public static void main (String[]args) throws IOException{ Scanner scan = new Scanner(System.in); int compareCount = 0; int low = 0; int high = 0; int mid = 0; int key = 0; Scanner temp; int[]list; String menu, outputString; int option = 1; boolean found = false; // Prompt the user to select an option menu = "\n\t1 Reads file" + "\n\t2 Finds a specific number in the list" + "\n\t3 Prints how many comparisons were needed" + "\n\t0 Quit\n\n\n"; System.out.println(menu); System.out.print("\tEnter your selection: "); option = scan.nextInt(); // Keep reading data until the user enters 0 while (option != 0) { switch (option) { case 1: readFile(); break; case 2: findKey(list,low,high,key); break; case 3: printCount(); break; default: outputString = "\nInvalid Selection\n"; System.out.println(outputString); break; }//end of switch System.out.println(menu); System.out.print("\tEnter your selection: "); option = scan.nextInt(); }//end of while }//end of main public static void readFile() { int i = 0; temp = new Scanner(new File("CS1302_Data7_2010.txt")); while(temp.hasNext()) { list[i]= temp.nextInt(); i++; }//end of while temp.close(); System.out.println("File Found..."); }//end of readFile() public static void findKey() { while(found!=true) { while(key < 100 || key > 999) { System.out.println("Please enter the number you would like to search for? ie 350: "); key = scan.nextInt(); }//end of inside while //base if (low <= high) { mid = ((low+high)/2); if (key == list[mid]) { found = true; compareCount++; }//end of inside if }//end of outside if else if (key < list[mid]) { compareCount++; high = mid-1; findKey(list,low,high,key); }//end of else if else { compareCount++; low = mid+1; findKey(list,low,high,key); }//end of else }//end of outside while }//end of findKey() public static void printCount() { System.out.println("Total number of comparisons is: " + compareCount); }//end of printCount }//end of class

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• Visual C++ 2010 Winform Errors C2238, C2059, C1075.

  - by tracelez

  It errors when I try compile. I cut the code out of the program and the program works and complies correctly. Not sure why it doesn't like this. This part of the code does single digit math with numeric strings that are converted into a char arrays. ** Error 2 error C2238: unexpected token(s) preceding ';' C:\Users\Alpha\documents\visual studio 2010\Projects\Win32 Form c++\Win32 Form c++\Win32 Form c++.cpp 10 1 Win32 Form c++ ** Error 1 error C2059: syntax error : 'namespace' C:\Users\Alpha\documents\visual studio 2010\Projects\Win32 Form c++\Win32 Form c++\Win32 Form c++.cpp 10 1 Win32 Form c++ ** Error 3 error C1075: end of file found before the left brace '{' at 'c:\users\alpha\documents\visual studio 2010\projects\win32 form c++\win32 form c++\Form1.h(40)' was matched C:\Users\Alpha\documents\visual studio 2010\Projects\Win32 Form c++\Win32 Form c++\Win32 Form c++.cpp 23 1 Win32 Form c++ ////// ////// // chX[] and chY[] are char arrays from functional part of program std::reverse( chX, &chX[ strlen( chX ) ] ); std::reverse( chY, &chY[ strlen( chY ) ] ); // makes sure x is larger or equal to y...makes looping logic easier if (strlen(chX) < strlen(chY)) { char *chZ = chX; chX = chY; chY = chZ; } //Variables for this part of the program char chX2; char chY2; std::string strSum; int sum = 0; bool carryth1 = false; int x=0; int y=0; for (int i = 0; i <= (strlen(chX)-1); i++) { if (i <= strlen(chY)-1) { chX2= chX[i]; chY2= chY[i]; x = atoi(chX2); y = atoi(chY2); //x = atoi(chX[i]); sum = x+y+(int)carryth1; carryth1 = false; if (sum > 9) { if(i == 0) { sum -=10; strSum = itoa(sum); carryth1 = true; } else { sum -=10; strSum += itoa(sum); carryth1 = true; } } else { if(i == 0) { strSum = itoa(sum); } else { strSum += itoa(sum); } } else { y = 0; chX2= chX[i]; x = atoi(chX2); sum = x+y+(int)carryth1; if((i == strlen(chX)-1)&& (carryth1 == true) && (x == 9)) { strSum += "10"; } else { strSum = itoa(sum); } } std::reverse( strSum, &strSum[ strlen( strSum ) ] ); //Creates new string for txtDisplay this simplifies conversions String^ strDisplay = "X is " + gcnew String((strX1.c_str())) + " Y is " +gcnew String((strY1.c_str())) + " \r\n " ; strDisplay += "The sum of the X + Y = "; txtDisplay->Text = gcnew String((strSum.c_str())) ;

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• Advance way of using UIView convertRect method to detect CGRectIntersectsRect multiple times

  - by Chris

  I recently asked a question regarding collision detection within subviews, with a perfect answer. I've come to the last point in implementing the collision on my application but I've come across a new issue. Using convertRect was fine getting the CGRect from the subView. I needed it to be a little more complex as it wasn't exactly rectangles that needed to be detected. on XCode I created an abstract class called TileViewController. Amongst other properties it has a IBOutlet UIView *detectionView; I now have multiple classes that inherit from TileViewController, and each class there are multiple views nested inside the detectionView which I have created using Interface Builder. The idea is an object could be a certain shape or size, I've programatically placed these 'tiled' detection points bottom center of each object. A user can select an item and interactive with it, in this circumstance move it around. Here is my touchesMoved method -(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{ UITouch *touch = [[event allTouches] anyObject]; CGPoint location = [touch locationInView:touch.view]; interactiveItem.center = location; // The ViewController the user has chosen to interact with interactiveView.view.center = location; // checks if the user has selected an item to interact with if (interactiveItem) { // First get check there is more then 1 item in the collection NSUInteger assetCount = [itemViewCollection count]; //NSMutableArray that holds the ViewControllers int detectionCount = 0; // To count how many times a CGRectIntersectsRect occured UIView *parentView = self.view; // if there is more then 1 item begin collision detection if (assetCount > 1) { for (TileViewController *viewController in itemViewCollection) { if (viewController.view.tag != interactiveView.view.tag) { if (viewController.detectionView.subviews) { for (UIView *detectView in viewController.detectionView.subviews) { CGRect viewRect; viewRect = [detectView convertRect:[detectView frame] toView:parentView]; // I could have checked to see if the below has subViews but didn't - In my current implementation it does anyway for (UIView *detectInteractView in interactiveView.detectionView.subviews) { CGRect interactRect; interactRect = [detectInteractView convertRect:[detectInteractView frame] toView:parentView]; if (CGRectIntersectsRect(viewRect, interactRect) == 1) { NSLog(@"collision detected"); [detectView setBackgroundColor:[UIColor blueColor]]; [detectInteractView setBackgroundColor:[UIColor blueColor]]; detectionCount++; } else { [detectView setBackgroundColor:[UIColor yellowColor]]; [detectInteractView setBackgroundColor:[UIColor yellowColor]]; } } } } } } // Logic if no items collided if (detectionCount == 0) { NSLog(@"Do something"); } } } } Now the method itself works to an extent but I don't think it's working with the nested values properly as the detection is off. A simplified version of this method works - Using CGRectIntersectsRect on the detectionView itself so I'm wondering if I'm looping through and checking the views correctly? I wasn't sure whether it was comparing in the same view but I suspect it is, I did modify the code slightly at one point, rather then comparing the values in self.view I took the viewController.detectView's UIViews into the interactiveView.detectView but the outcome was the same. It's rigged so the subviews change colour, but they change colour when they are not even touching, and when they do touch the wrong UIviews are changing colour Many thanks in advance

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• Programmatically swap colors from a loaded bitmap to Red, Green, Blue or Gray, pixel by pixel.

  - by eyeClaxton

  Download source code here: http://www.eyeClaxton.com/download/delphi/ColorSwap.zip I would like to take a original bitmap (light blue) and change the colors (Pixel by Pixel) to the red, green, blue and gray equivalence relation. To get an idea of what I mean, I have include the source code and a screen shot. Any help would be greatly appreciated. If more information is needed, please feel free to ask. If you could take a look at the code below, I have three functions that I'm looking for help on. The functions "RGBToRed, RGBToGreen and RGBToRed" I can't seem to come up with the right formulas. unit MainUnit; interface uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, ExtCtrls, StdCtrls; type TMainFrm = class(TForm) Panel1: TPanel; Label1: TLabel; Panel2: TPanel; Label2: TLabel; Button1: TButton; BeforeImage1: TImage; AfterImage1: TImage; RadioGroup1: TRadioGroup; procedure FormCreate(Sender: TObject); procedure Button1Click(Sender: TObject); private { Private declarations } public { Public declarations } end; var MainFrm: TMainFrm; implementation {$R *.DFM} function RGBToGray(RGBColor: TColor): TColor; var Gray: Byte; begin Gray := Round( (0.90 * GetRValue(RGBColor)) + (0.88 * GetGValue(RGBColor)) + (0.33 * GetBValue(RGBColor))); Result := RGB(Gray, Gray, Gray); end; function RGBToRed(RGBColor: TColor): TColor; var Red: Byte; begin // Not sure of the algorithm for this color Result := RGB(Red, Red, Red); end; function RGBToGreen(RGBColor: TColor): TColor; var Green: Byte; begin // Not sure of the algorithm for this color Result := RGB(Green, Green, Green); end; function RGBToBlue(RGBColor: TColor): TColor; var Blue: Byte; begin // Not sure of the algorithm for this color Result := RGB(Blue, Blue, Blue); end; procedure TMainFrm.FormCreate(Sender: TObject); begin BeforeImage1.Picture.LoadFromFile('Images\RightCenter.bmp'); end; procedure TMainFrm.Button1Click(Sender: TObject); var Bitmap: TBitmap; I, X: Integer; Color: Integer; begin Bitmap := TBitmap.Create; try Bitmap.LoadFromFile('Images\RightCenter.bmp'); for X := 0 to Bitmap.Height do begin for I := 0 to Bitmap.Width do begin Color := ColorToRGB(Bitmap.Canvas.Pixels[I, X]); case Color of $00000000: ; // Skip any Color Here! else case RadioGroup1.ItemIndex of 0: Bitmap.Canvas.Pixels[I, X] := RGBToBlue(Color); 1: Bitmap.Canvas.Pixels[I, X] := RGBToRed(Color); 2: Bitmap.Canvas.Pixels[I, X] := RGBToGreen(Color); 3: Bitmap.Canvas.Pixels[I, X] := RGBToGray(Color); end; end; end; end; AfterImage1.Picture.Graphic := Bitmap; finally Bitmap.Free; end; end; end. Okay, I apologize for not making it clearer. I'm trying to take a bitmap (blue in color) and swap the blue pixels with another color. Like the shots below.

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• ASP.NET WebControl ITemplate child controls are null

  - by tster

  Here is what I want: I want a control to put on a page, which other developers can place form elements inside of to display the entities that my control is searching. I have the Searching logic all working. The control builds custom search fields and performs searches based on declarative C# classes implementing my SearchSpec interface. Here is what I've been trying: I've tried using ITemplate on a WebControl which implements INamingContainer I've tried implementing a CompositeControl The closest I can get to working is below. OK I have a custom WebControl [ AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal), AspNetHostingPermission(SecurityAction.InheritanceDemand, Level = AspNetHostingPermissionLevel.Minimal), DefaultProperty("SearchSpecName"), ParseChildren(true), ToolboxData("<{0}:SearchPage runat=\"server\"> </{0}:SearchPage>") ] public class SearchPage : WebControl, INamingContainer { [Browsable(false), PersistenceMode(PersistenceMode.InnerProperty), DefaultValue(typeof(ITemplate), ""), Description("Form template"), TemplateInstance(TemplateInstance.Single), TemplateContainer(typeof(FormContainer))] public ITemplate FormTemplate { get; set; } public class FormContainer : Control, INamingContainer{ } public Control MyTemplateContainer { get; private set; } [Bindable(true), Category("Behavior"), DefaultValue(""), Description("The class name of the SearchSpec to use."), Localizable(false)] public virtual string SearchSpecName { get; set; } [Bindable(true), Category("Behavior"), DefaultValue(true), Description("True if this is query mode."), Localizable(false)] public virtual bool QueryMode { get; set; } private SearchSpec _spec; private SearchSpec Spec { get { if (_spec == null) { Type type = Assembly.GetExecutingAssembly().GetTypes().Where(t => t.Name == SearchSpecName).First(); _spec = (SearchSpec)Assembly.GetExecutingAssembly().CreateInstance(type.Namespace + "." + type.Name); } return _spec; } } protected override void CreateChildControls() { if (FormTemplate != null) { MyTemplateContainer = new FormTemplateContainer(this); FormTemplate.InstantiateIn(MyTemplateContainer); Controls.Add(MyTemplateContainer); } else { Controls.Add(new LiteralControl("blah")); } } protected override void RenderContents(HtmlTextWriter writer) { // <snip> } protected override HtmlTextWriterTag TagKey { get { return HtmlTextWriterTag.Div; } } } public class FormTemplateContainer : Control, INamingContainer { private SearchPage parent; public FormTemplateContainer(SearchPage parent) { this.parent = parent; } } then the usage: <tster:SearchPage ID="sp1" runat="server" SearchSpecName="TestSearchSpec" QueryMode="False"> <FormTemplate> <br /> Test Name: <asp:TextBox ID="testNameBox" runat="server" Width="432px"></asp:TextBox> <br /> Owner: <asp:TextBox ID="ownerBox" runat="server" Width="427px"></asp:TextBox> <br /> Description: <asp:TextBox ID="descriptionBox" runat="server" Height="123px" Width="432px" TextMode="MultiLine" Wrap="true"></asp:TextBox> </FormTemplate> </tster:SearchPage> The problem is that in the CodeBehind, the page has members descriptionBox, ownerBox and testNameBox. However, they are all null. Furthermore, FindControl("ownerBox") returns null as does this.sp1.FindControl("ownerBox"). I have to do this.sp1.MyTemplateContainer.FindControl("ownerBox") to get the control. How can I make it so that the C# Code Behind will have the controls generated and not null in my Page_Load event so that developers can just do this: testNameBox.Text = "foo"; ownerBox.Text = "bar"; descriptionBox.Text = "baz";

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• Joystick input in Java

  - by typoknig

  Hi all, I am making a 2D game in Java and I want to use a joystick to control the movement of some crosshairs. Right now I have it so the mouse can control those crosshairs. My only criteria for this is that the control for the crosshair must stay in the game window unless a user clicks off into another window. Basically I want my game to capture whatever device is controlling the crosshairs much like a virtual machine captures a mouse. The joystick I am using (Thrustmaster Hotas Cougar) comes with some pretty advanced features, so that may make this easier (or harder). I have tried the solution listed on this page, but I am using a 64bit computer and for some reason it does not like that. I have also tried to use the key emulation feature of my joystick, but with little success. Here is what I have so far, any pointer would be appreciated. Main Class: import java.awt.Color; import java.awt.Cursor; import java.awt.event.MouseEvent; import java.awt.event.MouseMotionListener; import java.awt.Graphics; import java.awt.Image; import java.awt.image.BufferStrategy; import java.awt.image.MemoryImageSource; import java.awt.Point; import java.awt.Toolkit; import javax.swing.JFrame; public class Game extends JFrame implements MouseMotionListener{ private int windowWidth = 1280; private int windowHeight = 1024; private Crosshair crosshair; public static void main(String[] args) { new Game(); } public Game() { this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); this.setSize(windowWidth, windowHeight); this.setResizable(false); this.setLocation(0,0); this.setVisible(true); this.createBufferStrategy(2); addMouseMotionListener(this); initGame(); while(true) { long start = System.currentTimeMillis(); gameLoop(); while(System.currentTimeMillis()-start < 5) { //empty while loop } } } private void initGame() { hideCursor(); crosshair = new Crosshair (windowWidth/2, windowHeight/2); } private void gameLoop() { //game logic drawFrame(); } private void drawFrame() { BufferStrategy bf = this.getBufferStrategy(); Graphics g = (Graphics)bf.getDrawGraphics(); try { g = bf.getDrawGraphics(); Color darkBlue = new Color(0x010040); g.setColor(darkBlue); g.fillRect(0, 0, windowWidth, windowHeight); drawCrossHair(g); } finally { g.dispose(); } bf.show(); Toolkit.getDefaultToolkit().sync(); } private void drawCrossHair(Graphics g){ Color yellow = new Color (0xEDFF62); g.setColor(yellow); g.drawOval(crosshair.x, crosshair.y, 40, 40); g.fillArc(crosshair.x + 10, crosshair.y + 21 , 20, 20, -45, -90); g.fillArc(crosshair.x - 1, crosshair.y + 10, 20, 20, -135, -90); g.fillArc(crosshair.x + 10, crosshair.y - 1, 20, 20, -225, -90); g.fillArc(crosshair.x + 21, crosshair.y + 10, 20, 20, -315, -90); } @Override public void mouseDragged(MouseEvent e) { //empty method } @Override public void mouseMoved(MouseEvent e) { crosshair.x = e.getX(); crosshair.y = e.getY(); } private void hideCursor() { int[] pixels = new int[16 * 16]; Image image = Toolkit.getDefaultToolkit().createImage(new MemoryImageSource(16, 16, pixels, 0, 16)); Cursor transparentCursor = Toolkit.getDefaultToolkit().createCustomCursor(image, new Point(0, 0), "invisiblecursor"); getContentPane().setCursor(transparentCursor); } } Another Class: public class Crosshair{ public int x; public int y; public Crosshair(int x, int y) { this.x = x; this.y = y; } }

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• Contructor parameters for dependent classes with Unity Framework

  - by Onisemus

  I just started using the Unity Application Block to try to decouple my classes and make it easier for unit testing. I ran into a problem though that I'm not sure how to get around. Looked through the documentation and did some Googling but I'm coming up dry. Here's the situation: I have a facade-type class which is a chat bot. It is a singleton class which handles all sort of secondary classes and provides a central place to launch and configure the bot. I also have a class called AccessManager which, well, manages access to bot commands and resources. Boiled down to the essence, I have the classes set up like so. public class Bot { public string Owner { get; private set; } public string WorkingDirectory { get; private set; } private IAccessManager AccessManager; private Bot() { // do some setup // LoadConfig sets the Owner & WorkingDirectory variables LoadConfig(); // init the access mmanager AccessManager = new MyAccessManager(this); } public static Bot Instance() { // singleton code } ... } And the AccessManager class: public class MyAccessManager : IAccessManager { private Bot botReference; public MyAccesManager(Bot botReference) { this.botReference = botReference; SetOwnerAccess(botReference.Owner); } private void LoadConfig() { string configPath = Path.Combine( botReference.WorkingDirectory, "access.config"); // do stuff to read from config file } ... } I would like to change this design to use the Unity Application Block. I'd like to use Unity to generate the Bot singleton and to load the AccessManager interface in some sort of bootstrapping method that runs before anything else does. public static void BootStrapSystem() { IUnityContainer container = new UnityContainer(); // create new bot instance Bot newBot = Bot.Instance(); // register bot instance container.RegisterInstance<Bot>(newBot); // register access manager container.RegisterType<IAccessManager,MyAccessManager>(newBot); } And when I want to get a reference to the Access Manager inside the Bot constructor I can just do: IAcessManager accessManager = container.Resolve<IAccessManager>(); And elsewhere in the system to get a reference to the Bot singleton: // do this Bot botInstance = container.Resolve<Bot>(); // instead of this Bot botInstance = Bot.Instance(); The problem is the method BootStrapSystem() is going to blow up. When I create a bot instance it's going to try to resolve IAccessManager but won't be able to because I haven't registered the types yet (that's the next line). But I can't move the registration in front of the Bot creation because as part of the registration I need to pass the Bot as a parameter! Circular dependencies!! Gah!!! This indicates to me I have a flaw in the way I have this structured. But how do I fix it? Help!!

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• Deploying an HttpHandler web service

  - by baron

  I am trying to build a webservice that manipulates http requests POST and GET. Here is a sample: public class CodebookHttpHandler: IHttpHandler { public void ProcessRequest(HttpContext context) { if (context.Request.HttpMethod == "POST") { //DoHttpPostLogic(); } else if (context.Request.HttpMethod == "GET") { //DoHttpGetLogic(); } } ... public void DoHttpPostLogic() { ... } public void DoHttpGetLogic() { ... } I need to deploy this but I am struggling how to start. Most online references show making a website, but really, all I want to do is respond when an HttpPost is sent. I don't know what to put in the website, just want that code to run. Edit: I am following this site as its exactly what I'm trying to do. I have the website set up, I have the code for the handler in a .cs file, i have edited the web.config to add the handler for the file extension I need. Now I am at the step 3 where you tell IIS about this extension and map it to ASP.NET. Also I am using IIS 7 so interface is slightly different than the screenshots. This is the problem I have: 1) Go to website 2) Go to handler mappings 3) Go Add Script Map 4) request path - put the extension I want to handle 5) Executable- it seems i am told to set aspnet_isapi.dll here. Maybe this is incorrect? 6) Give name 7) Hit OK button: Add Script Map Do you want to allow this ISAPI extension? Click "Yes" to add the extension with an "Allowed" entry to the ISAPI and CGI Restrictions list or to update an existing extension entry to "Allowed" in the ISAPI and CGI Restrictions list. Yes No Cancel 8) Hit Yes Add Script Map The specified module required by this handler is not in the modules list. If you are adding a script map handler mapping, the IsapiModule or the CgiModule must be in the modules list. OK edit 2: Have just figured out that that managed handler had something to do with handlers witten in managed code, script map was to help configuring an executable and module mapping to work with http Modules. So I should be using option 1 - Add Managed Handler. See: http://yfrog.com/11managedhandlerp I know what my request path is for the file extension... and I know name (can call it whatever I like), so it must be the Type field I am struggling with. In the applications folder (in IIS) so far I just have the MyHandler.cs and web.config (Of course also a file with the extension I am trying to create the handler for!) edit3: progress So now I have the code and the web.config set up I test to see If I can browse to the filename.CustomExtension file: HTTP Error 404.3 - Not Found The page you are requesting cannot be served because of the extension configuration. If the page is a script, add a handler. If the file should be downloaded, add a MIME map. So in IIS7 I go to Handler Mappings and add it in. See this MSDN example, it is exactly what I am trying to follow The class looks like this: using System.Web; namespace HandlerAttempt2 { public class MyHandler : IHttpHandler { public MyHandler() { //TODO: Add constructor logic here } public void ProcessRequest(HttpContext context) { var objResponse = context.Response; objResponse.Write("<html><body><h1>It just worked"); objResponse.Write("</body></html>"); } public bool IsReusable { get { return true; } } } } I add the Handler in as follows: Request path: *.whatever Type: MyHandler (class name - this appears correct as per example!) Name: whatever Try to browse to the custom file again (this is in app pool as Integrated): HTTP Error 500.21 - Internal Server Error Handler "whatever" has a bad module "ManagedPipelineHandler" in its module list Try to browse to the custom file again (this is in app pool as CLASSIC): HTTP Error 404.17 - Not Found The requested content appears to be script and will not be served by the static file handler.

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• .NET 4.0 Dynamic object used statically?

  - by Kevin Won

  I've gotten quite sick of XML configuration files in .NET and want to replace them with a format that is more sane. Therefore, I'm writing a config file parser for C# applications that will take a custom config file format, parse it, and create a Python source string that I can then execute in C# and use as a static object (yes that's right--I want a static (not the static type dyanamic) object in the end). Here's an example of what my config file looks like: // my custom config file format GlobalName: ExampleApp Properties { ExternalServiceTimeout: "120" } Python { // this allows for straight python code to be added to handle custom config def MyCustomPython: return "cool" } Using ANTLR I've created a Lexer/Parser that will convert this format to a Python script. So assume I have that all right and can take the .config above and run my Lexer/Parser on it to get a Python script out the back (this has the added benefit of giving me a validation tool for my config). By running the resultant script in C# // simplified example of getting the dynamic python object in C# // (not how I really do it) ScriptRuntime py = Python.CreateRuntime(); dynamic conf = py.UseFile("conftest.py"); dynamic t = conf.GetConfTest("test"); I can get a dynamic object that has my configuration settings. I can now get my config file settings in C# by invoking a dynamic method on that object: //C# calling a method on the dynamic python object var timeout = t.GetProperty("ExternalServiceTimeout"); //the config also allows for straight Python scripting (via the Python block) var special = t.MyCustonPython(); of course, I have no type safety here and no intellisense support. I have a dynamic representation of my config file, but I want a static one. I know what my Python object's type is--it is actually newing up in instance of a C# class. But since it's happening in python, it's type is not the C# type, but dynamic instead. What I want to do is then cast the object back to the C# type that I know the object is: // doesn't work--can't cast a dynamic to a static type (nulls out) IConfigSettings staticTypeConfig = t as IConfigSettings Is there any way to figure out how to cast the object to the static type? I'm rather doubtful that there is... so doubtful that I took another approach of which I'm not entirely sure about. I'm wondering if someone has a better way... So here's my current tactic: since I know the type of the python object, I am creating a C# wrapper class: public class ConfigSettings : IConfigSettings that takes in a dynamic object in the ctor: public ConfigSettings(dynamic settings) { this.DynamicProxy = settings; } public dynamic DynamicProxy { get; private set; } Now I have a reference to the Python dynamic object of which I know the type. So I can then just put wrappers around the Python methods that I know are there: // wrapper access to the underlying dynamic object // this makes my dynamic object appear 'static' public string GetSetting(string key) { return this.DynamicProxy.GetProperty(key).ToString(); } Now the dynamic object is accessed through this static proxy and thus can obviously be passed around in the static C# world via interface, etc: // dependency inject the dynamic object around IBusinessLogic logic = new BusinessLogic(IConfigSettings config); This solution has the benefits of all the static typing stuff we know and love while at the same time giving me the option of 'bailing out' to dynamic too: // the DynamicProxy property give direct access to the dynamic object var result = config.DynamicProxy.MyCustomPython(); but, man, this seems rather convoluted way of getting to an object that is a static type in the first place! Since the whole dynamic/static interaction world is new to me, I'm really questioning if my solution is optimal or if I'm missing something (i.e. some way of casting that dynamic object to a known static type) about how to bridge the chasm between these two universes.

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• Emulating old-school sprite flickering (theory and concept)

  - by Jeffrey Kern

  I'm trying to develop an oldschool NES-style video game, with sprite flickering and graphical slowdown. I've been thinking of what type of logic I should use to enable such effects. I have to consider the following restrictions if I want to go old-school NES style: No more than 64 sprites on the screen at a time No more than 8 sprites per scanline, or for each line on the Y axis If there is too much action going on the screen, the system freezes the image for a frame to let the processor catch up with the action From what I've read up, if there were more than 64 sprites on the screen, the developer would only draw high-priority sprites while ignoring low-priority ones. They could also alternate, drawing each even numbered sprite on opposite frames from odd numbered ones. The scanline issue is interesting. From my testing, it is impossible to get good speed on the XBOX 360 XNA framework by drawing sprites pixel-by-pixel, like the NES did. This is why in old-school games, if there were too many sprites on a single line, some would appear if they were cut in half. For all purposes for this project, I'm making scanlines be 8 pixels tall, and grouping the sprites together per scanline by their Y positioning. So, dumbed down I need to come up with a solution that.... 64 sprites on screen at once 8 sprites per 'scanline' Can draw sprites based on priority Can alternate between sprites per frame Emulate slowdown Here is my current theory First and foremost, a fundamental idea I came up with is addressing sprite priority. Assuming values between 0-255 (0 being low), I can assign sprites priority levels, for instance: 0 to 63 being low 63 to 127 being medium 128 to 191 being high 192 to 255 being maximum Within my data files, I can assign each sprite to be a certain priority. When the parent object is created, the sprite would randomly get assigned a number between its designated range. I would then draw sprites in order from high to low, with the end goal of drawing every sprite. Now, when a sprite gets drawn in a frame, I would then randomly generate it a new priority value within its initial priority level. However, if a sprite doesn't get drawn in a frame, I could add 32 to its current priority. For example, if the system can only draw sprites down to a priority level of 135, a sprite with an initial priority of 45 could then be drawn after 3 frames of not being drawn (45+32+32+32=141) This would, in theory, allow sprites to alternate frames, allow priority levels, and limit sprites to 64 per screen. Now, the interesting question is how do I limit sprites to only 8 per scanline? I'm thinking that if I'm sorting the sprites high-priority to low-priority, iterate through the loop until I've hit 64 sprites drawn. However, I shouldn't just take the first 64 sprites in the list. Before drawing each sprite, I could check to see how many sprites were drawn in it's respective scanline via counter variables . For example: Y-values between 0 to 7 belong to Scanline 0, scanlineCount[0] = 0 Y-values between 8 to 15 belong to Scanline 1, scanlineCount[1] = 0 etc. I could reset the values per scanline for every frame drawn. While going down the sprite list, add 1 to the scanline's respective counter if a sprite gets drawn in that scanline. If it equals 8, don't draw that sprite and go to the sprite with the next lowest priority. SLOWDOWN The last thing I need to do is emulate slowdown. My initial idea was that if I'm drawing 64 sprites per frame and there's still more sprites that need to be drawn, I could pause the rendering by 16ms or so. However, in the NES games I've played, sometimes there's slowdown if there's not any sprite flickering going on whereas the game moves beautifully even if there is some sprite flickering. Perhaps give a value to each object that uses sprites on the screen (like the priority values above), and if the combined values of all objects w/ sprites surpass a threshold, introduce the sprite flickering? IN CONCLUSION... Does everything I wrote actually sound legitimate and could work, or is it a pipe dream? What improvements can you all possibly think with this game programming theory of mine?

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• Modern Java alternatives

  - by Ralph

  I'm not sure if stackoverflow is the best forum for this discussion. I have been a Java developer for 14 years and have written an enterprise-level (~500,000 line) Swing application that uses most of the standard library APIs. Recently, I have become disappointed with the progress that the language has made to "modernize" itself, and am looking for an alternative for ongoing development. I have considered moving to the .NET platform, but I have issues with using something the only runs well in Windows (I know about Mono, but that is still far behind Microsoft). I also plan on buying a new Macbook Pro as soon as Apple releases their new rumored Arrandale-based machines and want to develop in an environment that will feel "at home" in Unix/Linux. I have considered using Python or Ruby, but the standard Java library is arguably the largest of any modern language. In JVM-based languages, I looked at Groovy, but am disappointed with its performance. Rumor has it that with the soon-to-be released JDK7, with its InvokeDynamic instruction, this will improve, but I don't know how much. Groovy is also not truly a functional language, although it provides closures and some of the "functional" features on collections. It does not embrace immutability. I have narrowed my search down to two JVM-based alternatives: Scala and Clojure. Each has its strengths and weaknesses. I am looking for the stackoverflow readerships' opinions. I am not an expert at either of these languages; I have read 2 1/2 books on Scala and am currently reading Stu Halloway's book on Clojure. Scala is strongly statically typed. I know the dynamic language folks claim that static typing is a crutch for not doing unit testing, but it does provide a mechanism for compile-time location of a whole class of errors. Scala is more concise than Java, but not as much as Clojure. Scala's inter-operation with Java seems to be better than Clojure's, in that most Java operations are easier to do in Scala than in Clojure. For example, I can find no way in Clojure to create a non-static initialization block in a class derived from a Java superclass. For example, I like the Apache commons CLI library for command line argument parsing. In Java and Scala, I can create a new Options object and add Option items to it in an initialization block as follows (Java code): final Options options = new Options() { { addOption(new Option("?", "help", false, "Show this usage information"); // other options } }; I can't figure out how to the same thing in Clojure (except by using (doit...)), although that may reflect my lack of knowledge of the language. Clojure's collections are optimized for immutability. They rarely require copy-on-write semantics. I don't know if Scala's immutable collections are implemented using similar algorithms, but Rich Hickey (Clojure's inventor) goes out of his way to explain how that language's data structures are efficient. Clojure was designed from the beginning for concurrency (as was Scala) and with modern multi-core processors, concurrency takes on more importance, but I occasionally need to write simple non-concurrent utilities, and Scala code probably runs a little faster for these applications since it discourages, but does not prohibit, "simple" mutability. One could argue that one-off utilities do not have to be super-fast, but sometimes they do tasks that take hours or days to complete. I know that there is no right answer to this "question", but I thought I would open it up for discussion. If anyone has a suggestion for another JVM-based language that can be used for enterprise level development, please list it. Also, it is not my intent to start a flame war. Thanks, Ralph

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• How to overcome shortcomings in reporting from EAV database?

  - by David Archer

  The major shortcomings with Entity-Attribute-Value database designs in SQL all seem to be related to being able to query and report on the data efficiently and quickly. Most of the information I read on the subject warn against implementing EAV due to these problems and the commonality of querying/reporting for almost all applications. I am currently designing a system where almost all the fields necessary for data storage are not known at design/compile time and are defined by the end-user of the system. EAV seems like a good fit for this requirement but due to the problems I've read about, I am hesitant in implementing it as there are also some pretty heavy reporting requirements for this system as well. I think I've come up with a way around this but would like to pose the question to the SO community. Given that typical normalized database (OLTP) still isn't always the best option for running reports, a good practice seems to be having a "reporting" database (OLAP) where the data from the normalized database is copied to, indexed extensively, and possibly denormalized for easier querying. Could the same idea be used to work around the shortcomings of an EAV design? The main downside I see are the increased complexity of transferring the data from the EAV database to reporting as you may end up having to alter the tables in the reporting database as new fields are defined in the EAV database. But that is hardly impossible and seems to be an acceptable tradeoff for the increased flexibility given by the EAV design. This downside also exists if I use a non-SQL data store (i.e. CouchDB or similar) for the main data storage since all the standard reporting tools are expecting a SQL backend to query against. Do the issues with EAV systems mostly go away if you have a seperate reporting database for querying? EDIT: Thanks for the comments so far. One of the important things about the system I'm working on it that I'm really only talking about using EAV for one of the entities, not everything in the system. The whole gist of the system is to be able to pull data from multiple disparate sources that are not known ahead of time and crunch the data to come up with some "best known" data about a particular entity. So every "field" I'm dealing with is multi-valued and I'm also required to track history for each. The normalized design for this ends up being 1 table per field which makes querying it kind of painful anyway. Here are the table schemas and sample data I'm looking at (obviously changed from what I'm working on but I think it illustrates the point well): EAV Tables Person ------------------- - Id - Name - ------------------- - 123 - Joe Smith - ------------------- Person_Value ------------------------------------------------------------------- - PersonId - Source - Field - Value - EffectiveDate - ------------------------------------------------------------------- - 123 - CIA - HomeAddress - 123 Cherry Ln - 2010-03-26 - - 123 - DMV - HomeAddress - 561 Stoney Rd - 2010-02-15 - - 123 - FBI - HomeAddress - 676 Lancas Dr - 2010-03-01 - ------------------------------------------------------------------- Reporting Table Person_Denormalized ---------------------------------------------------------------------------------------- - Id - Name - HomeAddress - HomeAddress_Confidence - HomeAddress_EffectiveDate - ---------------------------------------------------------------------------------------- - 123 - Joe Smith - 123 Cherry Ln - 0.713 - 2010-03-26 - ---------------------------------------------------------------------------------------- Normalized Design Person ------------------- - Id - Name - ------------------- - 123 - Joe Smith - ------------------- Person_HomeAddress ------------------------------------------------------ - PersonId - Source - Value - Effective Date - ------------------------------------------------------ - 123 - CIA - 123 Cherry Ln - 2010-03-26 - - 123 - DMV - 561 Stoney Rd - 2010-02-15 - - 123 - FBI - 676 Lancas Dr - 2010-03-01 - ------------------------------------------------------ The "Confidence" field here is generated using logic that cannot be expressed easily (if at all) using SQL so my most common operation besides inserting new values will be pulling ALL data about a person for all fields so I can generate the record for the reporting table. This is actually easier in the EAV model as I can do a single query. In the normalized design, I end up having to do 1 query per field to avoid a massive cartesian product from joining them all together.

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• SCORM 2004 Sequencing: What Am I doing wrong?

  - by Van

  This quiz is the last SCO in a grouping of 4 SCOs. SCO 1,2,3 have to be completed before this quiz becomes available. The problem is that when 1,2,3 are completed the menu skips right over this quiz and goes to the first page in the next module. This quiz stats grayed out the entire time. I think it has to do with the precondition logic or the objectives but I've tried everything I can think of and nothing works. <item identifier="quiz1_100" identifierref="res-quiz1" isvisible="true"> <title>Quiz 1</title> <imsss:sequencing> <imsss:controlMode choice="true" choiceExit="false" flow="true" forwardOnly="false" useCurrentAttemptObjectiveInfo="false" useCurrentAttemptProgressInfo="false" /> <imsss:sequencingRules> <imsss:preConditionRule> <imsss:ruleConditions conditionCombination="any"> <imsss:ruleCondition referencedObjective="obj_1000_VHKP_test" operator="not" condition="objectiveStatusKnown" /> <imsss:ruleCondition referencedObjective="obj_2000_VHKP_test" operator="not" condition="objectiveStatusKnown" /> <imsss:ruleCondition referencedObjective="obj_3000_VHKP_test" operator="not" condition="objectiveStatusKnown" /> <imsss:ruleCondition referencedObjective="quiz_primary" operator="not" condition="objectiveStatusKnown" /> </imsss:ruleConditions> <imsss:ruleAction action="disabled" /> </imsss:preConditionRule> <imsss:preConditionRule> <imsss:ruleConditions conditionCombination="any"> <imsss:ruleCondition referencedObjective="obj_1000_VHKP_test" operator="not" condition="objectiveStatusKnown" /> <imsss:ruleCondition referencedObjective="obj_2000_VHKP_test" operator="not" condition="objectiveStatusKnown" /> <imsss:ruleCondition referencedObjective="obj_3000_VHKP_test" operator="not" condition="objectiveStatusKnown" /> <imsss:ruleCondition referencedObjective="quiz_primary" operator="not" condition="objectiveStatusKnown" /> </imsss:ruleConditions> <imsss:ruleAction action="skip" /> </imsss:preConditionRule> <imsss:preConditionRule> <imsss:ruleConditions conditionCombination="all"> <imsss:ruleCondition condition="completed" /> </imsss:ruleConditions> <imsss:ruleAction action="skip" /> </imsss:preConditionRule> </imsss:sequencingRules> <imsss:objectives> <imsss:primaryObjective objectiveID="quiz_primary" satisfiedByMeasure="true"> <imsss:minNormalizedMeasure>0.8</imsss:minNormalizedMeasure> <imsss:mapInfo targetObjectiveID="quiz_complete" writeNormalizedMeasure="true" writeSatisfiedStatus="true" /> </imsss:primaryObjective> <imsss:objective satisfiedByMeasure="false" objectiveID="obj_1000_VHKP_test"> <imsss:mapInfo targetObjectiveID="gObj_1000_VHKP" readSatisfiedStatus="true" readNormalizedMeasure="false" /> </imsss:objective> <imsss:objective satisfiedByMeasure="false" objectiveID="obj_2000_VHKP_test"> <imsss:mapInfo targetObjectiveID="gObj_2000_VHKP" readSatisfiedStatus="true" readNormalizedMeasure="false" /> </imsss:objective> <imsss:objective satisfiedByMeasure="false" objectiveID="obj_3000_VHKP_test"> <imsss:mapInfo targetObjectiveID="gObj_3000_VHKP" readSatisfiedStatus="true" readNormalizedMeasure="false" /> </imsss:objective> <!-- <imsss:objective satisfiedByMeasure="false" objectiveID="obj_quiz1"> <imsss:mapInfo targetObjectiveID="quiz_primary" readSatisfiedStatus="true" readNormalizedMeasure="false" /> </imsss:objective> --> <imsss:objective satisfiedByMeasure="false" objectiveID="course_complete"> <imsss:mapInfo targetObjectiveID="obj_EJBOWNADV_primary" readSatisfiedStatus="true" readNormalizedMeasure="false" /> </imsss:objective> </imsss:objectives> <imsss:deliveryControls tracked="true" completionSetByContent="true" objectiveSetByContent="false" /> </imsss:sequencing> </item>

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• If Nvidia Shield can stream a game via WiFi (~150-300Mbps), where is the 1-10Gbps wired streaming?

  - by Enigma

  Facts: It is surprising and uncharacteristic that a wireless game streaming solution is the *first to hit the market when a 1000mbps+ Ethernet connection would accomplish the same feat with roughly 6x the available bandwidth. 150-300mbps WiFi is in no way superior to a 1000mbps+ LAN connection aside from well wireless mobility. Throughout time, (since the internet was created) wired services have **always come first yet in this particular case, the opposite seems to be true. We had wired internet first, wired audio streaming, and wired video streaming all before their wireless counterparts. Why? Largely because the wireless bandwidth was and is inferior. Even today despite being significantly better and capable of a lot more, it is still inferior to a wired connection. Situation: Chief among these is that NVIDIA’s Shield handheld game console will be getting a microconsole-like mode, dubbed “Shield Console Mode”, that will allow the handheld to be converted into a more traditional TV-connected console. In console mode Shield can be controlled with a Bluetooth controller, and in accordance with the higher resolution of TVs will accept 1080p game streaming from a suitably equipped PC, versus 720p in handheld mode. With that said 1080p streaming will require additional bandwidth, and while 720p can be done over WiFi NVIDIA will be requiring a hardline GigE connection for 1080p streaming (note that Shield doesn’t have Ethernet, so this is presumably being done over USB). Streaming aside, in console mode Shield will also support its traditional local gaming/application functionality. - http://www.anandtech.com/show/7435/nvidia-consolidates-game-streaming-tech-under-gamestream-brand-announces-shield-console-mode ^ This is not acceptable to me for a number of reasons not to mention the ridiculousness of having a little screen+controller unit sitting there while using a secondary controller and screen instead. That kind of redundant absurdity exemplifies how wrong of a solution that is. They need a second product for this solution without the screen or controller for it to make sense... at which point your just buying a little computer that does what most other larger computers do better. While this secondary project will provide a wired connection, it still shouldn't be necessary to purchase a Shield to have this benefit. Not only this but Intel's WiDi claims game streaming support as well - wirelessly. Where is the wired streaming? All that is required, by my understanding, is the ability to decode H.264 video compression and transmit control/feedback so by any logical comparison, one (Nvidia especially) should have no difficulty in creating an application for PC's (win32/64 environment) that does the exact same thing their android app does. I have 2 video cards capable of streaming (encoding) H.264 so by right they must be capable of decoding it I would think. I should be able to stream to my second desktop or my laptop both of which by hardware comparison are superior to the Shield. I haven't found anything stating plans to allow non-shield owners to do this. Can a third party create this software or does it hinge on some limitation that only Nvidia can overcome? Reiteration of questions: Is there a technical reason (non marketing) for why Nvidia opted to bottleneck the streaming service with a wireless connection limiting the resolution to 720p and introducing intermittent video choppiness when on a wired connection one could achieve, presumably, 1080p with significantly less or zero choppiness? Is there anything limiting developers from creating a PC/Desktop application emulating the same H.264 decoding functionality that circumvents the need to get an Nvidia Shield altogether? (It is not a matter of being too cheap to support Nvidia - I have many Nvidia cards that aren't being used. One should not have to purchase specialty hardware when = hardware already exists) Same questions go for Intel Widi also. I am just utterly perplexed that there are wireless live streaming solution and yet no wired. How on earth can wireless be the goto transmission medium? Is there another solution that takes advantage of H.264 video compression allowing live streaming over a wired connection? (*) - Perhaps this isn't the first but afaik it is the first complete package. (**) - I cant back that up with hard evidence/links but someone probably could. Edit: Maybe this will be the solution I am looking for but I still find it hard to believe that they would be the first and after wireless solutions already exist. In-home Streaming You can play all your Windows and Mac games on your SteamOS machine, too. Just turn on your existing computer and run Steam as you always have - then your SteamOS machine can stream those games over your home network straight to your TV! - http://store.steampowered.com/livingroom/SteamOS/

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• WFP: How do you properly Bind a DependencyProperty to the GUI

  - by Robert Ross

  I have the following class (abreviated for simplicity). The app it multi-threaded so the Set and Get are a bit more complicated but should be ok. namespace News.RSS { public class FeedEngine : DependencyObject { public static readonly DependencyProperty _processing = DependencyProperty.Register("Processing", typeof(bool), typeof(FeedEngine), new FrameworkPropertyMetadata(true, FrameworkPropertyMetadataOptions.AffectsRender)); public bool Processing { get { return (bool)this.Dispatcher.Invoke( DispatcherPriority.Normal, (DispatcherOperationCallback)delegate { return GetValue(_processing); }, Processing); } set { this.Dispatcher.BeginInvoke(DispatcherPriority.Normal, (SendOrPostCallback)delegate { SetValue(_processing, value); }, value); } } public void Poll() { while (Running) { Processing = true; //Do my work to read the data feed from remote source Processing = false; Thread.Sleep(PollRate); } // } } } Next I have my main form as the following: <Window x:Class="News.Main" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:converter="clr-namespace:News.Converters" xmlns:local="clr-namespace:News.Lookup" xmlns:rss="clr-namespace:News.RSS" Title="News" Height="521" Width="927" Initialized="Window_Initialized" Closing="Window_Closing" > <Window.Resources> <ResourceDictionary> <converter:BooleanConverter x:Key="boolConverter" /> <converter:ArithmeticConverter x:Key="arithConverter" /> ... </ResourceDictionary> </Window.Resources> <DockPanel Name="dockPanel1" SnapsToDevicePixels="False" > <ToolBarPanel Height="37" Name="toolBarPanel" Orientation="Horizontal" DockPanel.Dock="Top" > <ToolBarPanel.Children> <Button DataContext="{DynamicResource FeedEngine}" HorizontalAlignment="Right" Name="btnSearch" ToolTip="Search" Click="btnSearch_Click" IsEnabled="{Binding Path=Processing, Converter={StaticResource boolConverter}}"> <Image Width="32" Height="32" Name="imgSearch" Source="{Resx ResxName=News.Properties.Resources, Key=Search}" /> </Button> ... </DockPanel> </Window> As you can see I set the DataContext to FeedEngine and Bind IsEnabled to Processing. I have also tested the boolConverter separately and it functions (just applies ! (Not) to a bool). Here is my Main window code behind in case it helps to debug. namespace News { /// <summary> /// Interaction logic for Main.xaml /// </summary> public partial class Main : Window { public FeedEngine _engine; List<NewsItemControl> _newsItems = new List<NewsItemControl>(); Thread _pollingThread; public Main() { InitializeComponent(); this.Show(); } private void Window_Initialized(object sender, EventArgs e) { // Load current Feed data. _engine = new FeedEngine(); ThreadStart start = new ThreadStart(_engine.Poll); _pollingThread = new Thread(start); _pollingThread.Start(); } } } Hope someone can see where I missed a step. Thanks.

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• Does anyone have database, programming language/framework suggestions for a GUI point of sale system

  - by Jason Down

  Our company has a point of sale system with many extras, such as ordering and receiving functionality, sales and order history etc. Our main issue is that the system was not designed properly from the ground up, so it takes too long to make fixes and handle requests from our customers. Also, the current technology we are using (Progress database, Progress 4GL for the language) incurs quite a bit of licensing expenses on our customers due to mutli-user license fees for database connections etc. After a lot of discussion it is looking like we will probably start over from scratch (while maintaining the current product at least for the time being). We are looking for a couple of things: Create the system with a nice GUI front end (it is currently CHUI and the application was not built in a way that allows us to redesign the front end... no layering or separation of business logic and gui...shudder). Create the system with the ability to modularize different functionality so the product doesn't have to include all features. This would keep the cost down for our current customers that want basic functionality and a lower price tag. The bells and whistles would be available for those that would want them. Use proper design patterns to make the product easy to add or change any part at any time (i.e. change the database or change the front end without needing to rewrite the application or most of it). This is a problem today because the Progress 4GL code is directly compiled against the database. Small changes in the database requires lots of code recompiling. Our new system will be Linux based, with a possibility of a client application providing functionality from one or more windows boxes. So what I'm looking for is any suggestions on which database and/or framework or programming language(s) someone might recommend for this sort of product. Anyone that has experience in this field might be able to point us in the right direction or even have some ideas of what to avoid. We have considered .NET and SQL Express (we don't need an enterprise level DB), but that would limit us to windows (as far as I know anyway). I have heard of Mono for writing .NET code in a Linux environment, but I don't know much about it yet. We've also considered a Java and MySql based implementation. To summarize we are looking to do the following: Keep licensing costs down on the technology we will use to develop the product (Oracle, yikes! MySQL, nice.) Deliver a solution that is easily maintainable and supportable. A solution that has a component capable of running on "old" hardware through a CHUI front end. (some of our customers have 40+ terminals which would be a ton of cash in order to convert over to a PC). Suggestions would be appreciated. Thanks [UPDATE] I should note that we are currently performing a total cost analysis. This question is intended to give us a couple of "educated" options to look into to include in or analysis. Anyone who could share experiences/suggestions about client/server setups would be appreciated (not just those who have experience with point of sale systems... that would just be a bonus).

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• Mysql - Help me change this single complex query to use temporary tables

  - by sandeepan-nath

  About the system: - There are tutors who create classes and packs - A tags based search approach is being followed.Tag relations are created when new tutors register and when tutors create packs (this makes tutors and packs searcheable). For details please check the section How tags work in this system? below. Following is the concerned query Can anybody help me suggest an approach using temporary tables. We have indexed all the relevant fields and it looks like this is the least time possible with this approach:- SELECT SUM(DISTINCT( t.tag LIKE "%Dictatorship%" OR tt.tag LIKE "%Dictatorship%" OR ttt.tag LIKE "%Dictatorship%" )) AS key_1_total_matches , SUM(DISTINCT( t.tag LIKE "%democracy%" OR tt.tag LIKE "%democracy%" OR ttt.tag LIKE "%democracy%" )) AS key_2_total_matches , COUNT(DISTINCT( od.id_od )) AS tutor_popularity, CASE WHEN ( IF(( wc.id_wc > 0 ), ( wc.wc_api_status = 1 AND wc.wc_type = 0 AND wc.class_date > '2010-06-01 22:00:56' AND wccp.status = 1 AND ( wccp.country_code = 'IE' OR wccp.country_code IN ( 'INT' ) ) ), 0) ) THEN 1 ELSE 0 END AS 'classes_published' , CASE WHEN ( IF(( lp.id_lp > 0 ), ( lp.id_status = 1 AND lp.published = 1 AND lpcp.status = 1 AND ( lpcp.country_code = 'IE' OR lpcp.country_code IN ( 'INT' ) ) ), 0) ) THEN 1 ELSE 0 END AS 'packs_published', td . *, u . * FROM tutor_details AS td JOIN users AS u ON u.id_user = td.id_user LEFT JOIN learning_packs_tag_relations AS lptagrels ON td.id_tutor = lptagrels.id_tutor LEFT JOIN learning_packs AS lp ON lptagrels.id_lp = lp.id_lp LEFT JOIN learning_packs_categories AS lpc ON lpc.id_lp_cat = lp.id_lp_cat LEFT JOIN learning_packs_categories AS lpcp ON lpcp.id_lp_cat = lpc.id_parent LEFT JOIN learning_pack_content AS lpct ON ( lp.id_lp = lpct.id_lp ) LEFT JOIN webclasses_tag_relations AS wtagrels ON td.id_tutor = wtagrels.id_tutor LEFT JOIN webclasses AS wc ON wtagrels.id_wc = wc.id_wc LEFT JOIN learning_packs_categories AS wcc ON wcc.id_lp_cat = wc.id_wp_cat LEFT JOIN learning_packs_categories AS wccp ON wccp.id_lp_cat = wcc.id_parent LEFT JOIN order_details AS od ON td.id_tutor = od.id_author LEFT JOIN orders AS o ON od.id_order = o.id_order LEFT JOIN tutors_tag_relations AS ttagrels ON td.id_tutor = ttagrels.id_tutor LEFT JOIN tags AS t ON t.id_tag = ttagrels.id_tag LEFT JOIN tags AS tt ON tt.id_tag = lptagrels.id_tag LEFT JOIN tags AS ttt ON ttt.id_tag = wtagrels.id_tag WHERE ( u.country = 'IE' OR u.country IN ( 'INT' ) ) AND CASE WHEN ( ( tt.id_tag = lptagrels.id_tag ) AND ( lp.id_lp > 0 ) ) THEN lp.id_status = 1 AND lp.published = 1 AND lpcp.status = 1 AND ( lpcp.country_code = 'IE' OR lpcp.country_code IN ( 'INT' ) ) ELSE 1 END AND CASE WHEN ( ( ttt.id_tag = wtagrels.id_tag ) AND ( wc.id_wc > 0 ) ) THEN wc.wc_api_status = 1 AND wc.wc_type = 0 AND wc.class_date > '2010-06-01 22:00:56' AND wccp.status = 1 AND ( wccp.country_code = 'IE' OR wccp.country_code IN ( 'INT' ) ) ELSE 1 END AND CASE WHEN ( od.id_od > 0 ) THEN od.id_author = td.id_tutor AND o.order_status = 'paid' AND CASE WHEN ( od.id_wc > 0 ) THEN od.can_attend_class = 1 ELSE 1 END ELSE 1 END AND ( t.tag LIKE "%Dictatorship%" OR t.tag LIKE "%democracy%" OR tt.tag LIKE "%Dictatorship%" OR tt.tag LIKE "%democracy%" OR ttt.tag LIKE "%Dictatorship%" OR ttt.tag LIKE "%democracy%" ) GROUP BY td.id_tutor HAVING key_1_total_matches = 1 AND key_2_total_matches = 1 ORDER BY tutor_popularity DESC, u.surname ASC, u.name ASC LIMIT 0, 20 The problem The results returned by the above query are correct (AND logic working as per expectation), but the time taken by the query rises alarmingly for heavier data and for the current data I have it is like 10 seconds as against normal query timings of the order of 0.005 - 0.0002 seconds, which makes it totally unusable. Somebody suggested in my previous question to do the following:- create a temporary table and insert here all relevant data that might end up in the final result set run several updates on this table, joining the required tables one at a time instead of all of them at the same time finally perform a query on this temporary table to extract the end result All this was done in a stored procedure, the end result has passed unit tests, and is blazing fast. I have never worked with temporary tables till now. Only if I could get some hints, kind of schematic representations so that I can start with... Is there something faulty with the query? What can be the reason behind 10+ seconds of execution time? How tags work in this system? When a tutor registers, tags are entered and tag relations are created with respect to tutor's details like name, surname etc. When a Tutors create packs, again tags are entered and tag relations are created with respect to pack's details like pack name, description etc. tag relations for tutors stored in tutors_tag_relations and those for packs stored in learning_packs_tag_relations. All individual tags are stored in tags table. The explain query output:- Please see this screenshot - http://www.test.examvillage.com/Explain_query_improved.jpg

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• Scope quandary with namespaces, function templates, and static data

  - by Adrian McCarthy

  This scoping problem seems like the type of C++ quandary that Scott Meyers would have addressed in one of his Effective C++ books. I have a function, Analyze, that does some analysis on a range of data. The function is called from a few places with different types of iterators, so I have made it a template (and thus implemented it in a header file). The function depends on a static table of data, AnalysisTable, that I don't want to expose to the rest of the code. My first approach was to make the table a static const inside Analysis. namespace MyNamespace { template <typename InputIterator> int Analyze(InputIterator begin, InputIterator end) { static const int AnalysisTable[] = { /* data */ }; ... // implementation uses AnalysisTable return result; } } // namespace MyNamespace It appears that the compiler creates a copy of AnalysisTable for each instantiation of Analyze, which is wasteful of space (and, to a small degree, time). So I moved the table outside the function like this: namespace MyNamespace { const int AnalysisTable[] = { /* data */ }; template <typename InputIterator> int Analyze(InputIterator begin, InputIterator end) { ... // implementation uses AnalysisTable return result; } } // namespace MyNamespace There's only one copy of the table now, but it's exposed to the rest of the code. I'd rather keep this implementation detail hidden, so I introduced an unnamed namespace: namespace MyNamespace { namespace { // unnamed to hide AnalysisTable const int AnalysisTable[] = { /* data */ }; } // unnamed namespace template <typename InputIterator> int Analyze(InputIterator begin, InputIterator end) { ... // implementation uses AnalysisTable return result; } } // namespace MyNamespace But now I again have multiple copies of the table, because each compilation unit that includes this header file gets its own. If Analyze weren't a template, I could move all the implementation detail out of the header file. But it is a template, so I seem stuck. My next attempt was to put the table in the implementation file and to make an extern declaration within Analyze. // foo.h ------ namespace MyNamespace { template <typename InputIterator> int Analyze(InputIterator begin, InputIterator end) { extern const int AnalysisTable[]; ... // implementation uses AnalysisTable return result; } } // namespace MyNamespace // foo.cpp ------ #include "foo.h" namespace MyNamespace { const int AnalysisTable[] = { /* data */ }; } This looks like it should work, and--indeed--the compiler is satisfied. The linker, however, complains, "unresolved external symbol AnalysisTable." Drat! (Can someone explain what I'm missing here?) The only thing I could think of was to give the inner namespace a name, declare the table in the header, and provide the actual data in an implementation file: // foo.h ----- namespace MyNamespace { namespace PrivateStuff { extern const int AnalysisTable[]; } // unnamed namespace template <typename InputIterator> int Analyze(InputIterator begin, InputIterator end) { ... // implementation uses PrivateStuff::AnalysisTable return result; } } // namespace MyNamespace // foo.cpp ----- #include "foo.h" namespace MyNamespace { namespace PrivateStuff { const int AnalysisTable[] = { /* data */ }; } } Once again, I have exactly one instance of AnalysisTable (yay!), but other parts of the program can access it (boo!). The inner namespace makes it a little clearer that they shouldn't, but it's still possible. Is it possible to have one instance of the table and to move the table beyond the reach of everything but Analyze?

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• multiple-inheritance substitution

  - by Luigi

  I want to write a module (framework specific), that would wrap and extend Facebook PHP-sdk (https://github.com/facebook/php-sdk/). My problem is - how to organize classes, in a nice way. So getting into details - Facebook PHP-sdk consists of two classes: BaseFacebook - abstract class with all the stuff sdk does Facebook - extends BaseFacebook, and implements parent abstract persistance-related methods with default session usage Now I have some functionality to add: Facebook class substitution, integrated with framework session class shorthand methods, that run api calls, I use mostly (through BaseFacebook::api()), authorization methods, so i don't have to rewrite this logic every time, configuration, sucked up from framework classes, insted of passed as params caching, integrated with framework cache module I know something has gone very wrong, because I have too much inheritance that doesn't look very normal.Wrapping everything in one "complex extension" class also seems too much. I think I should have few working togheter classes - but i get into problems like: if cache class doesn't really extend and override BaseFacebook::api() method - shorthand and authentication classes won't be able to use the caching. Maybe some kind of a pattern would be right in here? How would you organize these classes and their dependencies? EDIT 04.07.2012 Bits of code, related to the topic: This is how the base class of Facebook PHP-sdk: abstract class BaseFacebook { // ... some methods public function api(/* polymorphic */) { // ... method, that makes api calls } public function getUser() { // ... tries to get user id from session } // ... other methods abstract protected function setPersistentData($key, $value); abstract protected function getPersistentData($key, $default = false); // ... few more abstract methods } Normaly Facebook class extends it, and impelements those abstract methods. I replaced it with my substitude - Facebook_Session class: class Facebook_Session extends BaseFacebook { protected function setPersistentData($key, $value) { // ... method body } protected function getPersistentData($key, $default = false) { // ... method body } // ... implementation of other abstract functions from BaseFacebook } Ok, then I extend this more with shorthand methods and configuration variables: class Facebook_Custom extends Facebook_Session { public funtion __construct() { // ... call parent's constructor with parameters from framework config } public function api_batch() { // ... a wrapper for parent's api() method return $this->api('/?batch=' . json_encode($calls), 'POST'); } public function redirect_to_auth_dialog() { // method body } // ... more methods like this, for common queries / authorization } I'm not sure, if this isn't too much for a single class ( authorization / shorthand methods / configuration). Then there comes another extending layer - cache: class Facebook_Cache extends Facebook_Custom { public function api() { $cache_file_identifier = $this->getUser(); if(/* cache_file_identifier is not null and found a valid file with cached query result */) { // return the result } else { try { // call Facebook_Custom::api, cache and return the result } catch(FacebookApiException $e) { // if Access Token is expired force refreshing it parent::redirect_to_auth_dialog(); } } } // .. some other stuff related to caching } Now this pretty much works. New instance of Facebook_Cache gives me all the functionality. Shorthand methods from Facebook_Custom use caching, because Facebook_Cache overwrited api() method. But here is what is bothering me: I think it's too much inheritance. It's all very tight coupled - like look how i had to specify 'Facebook_Custom::api' instead of 'parent:api', to avoid api() method loop on Facebook_Cache class extending. Overall mess and ugliness. So again, this works but I'm just asking about patterns / ways of doing this in a cleaner and smarter way.

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