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  • When to choose which machine learning classifier?

    - by LM
    Suppose I'm working on some classification problem. (Fraud detection and comment spam are two problems I'm working on right now, but I'm curious about any classification task in general.) How do I know which classifier I should use? (Decision tree, SVM, Bayesian, logistic regression, etc.) In which cases is one of them the "natural" first choice, and what are the principles for choosing that one? Examples of the type of answers I'm looking for (from Manning et al.'s "Introduction to Information Retrieval book": http://nlp.stanford.edu/IR-book/html/htmledition/choosing-what-kind-of-classifier-to-use-1.html): a. If your data is labeled, but you only have a limited amount, you should use a classifier with high bias (for example, Naive Bayes). [I'm guessing this is because a higher-bias classifier will have lower variance, which is good because of the small amount of data.] b. If you have a ton of data, then the classifier doesn't really matter so much, so you should probably just choose a classifier with good scalability. What are other guidelines? Even answers like "if you'll have to explain your model to some upper management person, then maybe you should use a decision tree, since the decision rules are fairly transparent" are good. I care less about implementation/library issues, though. Also, for a somewhat separate question, besides standard Bayesian classifiers, are there 'standard state-of-the-art' methods for comment spam detection (as opposed to email spam)? [Not sure if stackoverflow is the best place to ask this question, since it's more machine learning than actual programming -- if not, any suggestions for where else?]

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  • CSS Background image in Redmine template arbitrarily not loading

    - by Pekka
    I`m in the process of building a template for Redmine (a project management system based on Ruby on Rails.) Ruby is running on a virtual server from a Bitnami.org installation package. The OS is Windows. The template essentially consists of a styles.css file. In that file, I have the following line: #header { padding: 0px; padding-top: 48px; background-color: #62DFFF; background-image: url(../images/bkg.jpg) background-position: center bottom; background-repeat: repeat-x; height:150px; } It's a header element with a background image. The problem: This background image arbitrarily appears and disappears when reloading. Say you reload ten times in twenty seconds; the image will appear in two instances, and be missing in the 18 others. I would have put this down to server problems, but the weird thing is that when it's missing, the request for the image doesn't appear in Firebug's net tab at all. Even if it were cached, the request should be there. Raw screenshots of the identical page on two reloads: I am 100% sure the CSS file does not change in between. I have examined both instances with Firebug and the CSS is identical. It happens in both Firefox and Chrome so it must be something basic I'm overlooking. What could be causing a browser not to load a resource at all? I have zero idea about Ruby nor Rails - getting Redmine running and customized is all I have ever had to do with this platform - so I don't really know where to look. Apache's, Mongrel's and Redmine's error logs look fine, though.

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  • How can I tackle 'profoundly found elsewhere' syndrome (inverse of NIH)?

    - by Alistair Knock
    How can I encourage colleagues to embrace small-scale innovation within our team(s), in order to get things done quicker and to encourage skills development? (the term 'profoundly found elsewhere' comes from Wikipedia, although it is scarcely used anywhere else apart from a reference to Proctor & Gamble) I've worked in both environments where there is a strong opposition to software which hasn't been developed in-house (usually because there's a large community of developers), and more recently (with far fewer central developers) where off-the-shelf products are far more favoured for the usual reasons: maintenance, total cost over product lifecycle, risk management and so on. I think the off the shelf argument works in the majority of cases for the majority of users, even though as a developer the product never quite does what I'd like it to do. However, in some cases there are clear gaps where the market isn't able to provide specifically what we would need, or at least it isn't able to without charging astronomical consultancy rates for a bespoke solution. These can be small web applications which provide a short-term solution to a particular need in one specific department, or could be larger developments that have the potential to serve a wider audience, both across the organisation and into external markets. The problem is that while development of these applications would be incredibly cheap in terms of developer hours, and delivered very quickly without the need for glacial consultation, the proposal usually falls flat because of risk: 'Who'll maintain the project tracker that hasn't had any maintenance for the past 7 years while you're on holiday for 2 weeks?' 'What if one of our systems changes and the connector breaks?' 'How can you guarantee it's secure/better/faster/cheaper/holier than Company X's?' With one developer behind these little projects, the answers are invariably: 'Nobody, but...' 'It will break, just like any other application would...' 'I, uh...' How can I better answer these questions and encourage people to take a little risk in order to stimulate creativity and fast-paced, short-lifecycle development instead of using that 6 months to consult about what tender process we might use?

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  • Passing Derived Class Instances as void* to Generic Callbacks in C++

    - by Matthew Iselin
    This is a bit of an involved problem, so I'll do the best I can to explain what's going on. If I miss something, please tell me so I can clarify. We have a callback system where on one side a module or application provides a "Service" and clients can perform actions with this Service (A very rudimentary IPC, basically). For future reference let's say we have some definitions like so: typedef int (*callback)(void*); // This is NOT in our code, but makes explaining easier. installCallback(string serviceName, callback cb); // Really handled by a proper management system sendMessage(string serviceName, void* arg); // arg = value to pass to callback This works fine for basic types such as structs or builtins. We have an MI structure a bit like this: Device <- Disk <- MyDiskProvider class Disk : public virtual Device class MyDiskProvider : public Disk The provider may be anything from a hardware driver to a bit of glue that handles disk images. The point is that classes inherit Disk. We have a "service" which is to be notified of all new Disks in the system, and this is where things unravel: void diskHandler(void *p) { Disk *pDisk = reinterpret_cast<Disk*>(p); // Uh oh! // Remainder is not important } SomeDiskProvider::initialise() { // Probe hardware, whatever... // Tell the disk system we're here! sendMessage("disk-handler", reinterpret_cast<void*>(this)); // Uh oh! } The problem is, SomeDiskProvider inherits Disk, but the callback handler can't receive that type (as the callback function pointer must be generic). Could RTTI and templates help here? Any suggestions would be greatly appreciated.

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  • JTA or LOCAL transactions in JPA2+Hibernate 3.6.0?

    - by Pangea
    We are in the process of re-thinking our tech stack and below are our choices (We can't live without Spring and Hibernate due to the complexity etc of the app). We are also moving from J2EE 1.4 to JEE 5. Tech stack JEE 5 JPA 2.0 (I know JEE 5 only supports JPA 1.0 but we want to use Hibernate as the JPA provider) Hibernate 3.6.0 (We already have lots of hbm files with custom types etc. so we doesn't want to migrate them at this time to JPA. This means we want both jpa/hbm mappings work together and hence the Hibernate as the JPA provider instead of using the default that comes with App Server) Now the problems is that I want to stick with local transactions but other team members want to use JTA. I have been working with J2EE for last 9 years and I've heard time and again people suggesting to stick with local transactions if I doesn't need two phase commits. This is not only for performance reasons but debugging/troubleshooting a local transaction is lot easier than a distributed transaction. My suggestion is to use spring declarative transaction management + local transactions (HibernateTransactionManager) I want to make sure if I am being paranoid or I have a valid point. I'd like to hear what the rest of the JEE world thinks. Thank you.

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  • Why do I get "request for member in something not a struct or union" from this code?

    - by pyroxene
    I'm trying to teach myself C by coding up a linked list. I'm new to pointers and memory management and I'm getting a bit confused. I have this code: /* Remove a node from the list and rejiggle the pointers */ void rm_node(struct node **listP, int index) { struct node *prev; struct node *n = *listP; if (index == 0) { *listP = *listP->next; free(n); return; } for (index; index > 0; index--) { n = n->next; if (index == 2) { prev = n; } } prev->next = n->next; free(n); } to remove an element from the list. If I want to remove the first node, I still need some way of referring to the list, which is why the listP arg is a double pointer, so it can point to the first element of the list and allow me to free the node that used to be the head. However, when I try to dereference listP to access the pointer to the next node, the compiler tells me error: request for member ‘next’ in something not a structure or union . What am I doing wrong here? I think I might be hopelessly mixed up..?

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  • Problem saving file on Motorola Droid, Android 2.1?

    - by Rob Kent
    Two of my users have reported a problem with my Android application, OftSeen Gestures. Both of them are using a Motorola Droid. The app saves a text file which is just a list of gesture names and phone numbers, both strings. It saves the file to the private data area. I don't know that it is this code that is failing but they report the assigned numbers disappearing after the phone comes out of screen sleep. Since the file is reread in OnCreate each time, I'm assuming the file doesn't exist on return. As soon as I can get my hands on a Droid I will debug it but in the meantime can you see a reason why this save operation would fail on Droid (no other users have reported this)? OutputStreamWriter out = new OutputStreamWriter(AppGlobal.getContext().openFileOutput(MAPPINGS_FILE_NAME, 0)); for (String key : mMap.keySet()) { String number = mMap.get(key).number; out.write(String.format("%s,%s\n", key, number == null ? "" : number)); } out.close(); AppGlobal.getContext returns the application context and the MAPPINGS_FILE_NAME resolves to "gesture_mappings.txt". Like I say, I don't know that this is the problem. It could be something else to do with state management inside the app. If anyone has a Droid, maybe they could download the app from Market and test it for me? Note this is a genuine request for help - not an attempt to increase my downloads.

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  • Wildcards in T-SQL LIKE vs. ASP.net parameters

    - by Vinzcent
    In my SQL statement I use wildcards. But when I try to select something, it never select something. While when I execute the query in Microsoft SQL Server Management Studio, it works fine. What am I doing wrong? Click handler protected void btnTitelAuteur_Click(object sender, EventArgs e) { cvalTitelAuteur.Enabled = true; cvalTitelAuteur.Validate(); if (Page.IsValid) { objdsSelectedBooks.SelectMethod = "getBooksByTitleAuthor"; objdsSelectedBooks.SelectParameters.Clear(); objdsSelectedBooks.SelectParameters.Add(new Parameter("title", DbType.String)); objdsSelectedBooks.SelectParameters.Add(new Parameter("author", DbType.String)); objdsSelectedBooks.Select(); gvSelectedBooks.DataBind(); pnlZoeken.Visible = false; pnlKiezen.Visible = true; } } In my Data Access Layer public static DataTable getBooksByTitleAuthor(string title, string author) { string sql = "SELECT 'AUTHOR' = tblAuthors.FIRSTNAME + ' ' + tblAuthors.LASTNAME, tblBooks.*, tblGenres.GENRE " + "FROM tblAuthors INNER JOIN tblBooks ON tblAuthors.AUTHOR_ID = tblBooks.AUTHOR_ID INNER JOIN tblGenres ON tblBooks.GENRE_ID = tblGenres.GENRE_ID " +"WHERE (tblBooks.TITLE LIKE '%@title%');"; SqlDataAdapter da = new SqlDataAdapter(sql, GetConnectionString()); da.SelectCommand.Parameters.Add("@title", SqlDbType.Text); da.SelectCommand.Parameters["@title"].Value = title; DataSet ds = new DataSet(); da.Fill(ds, "Books"); return ds.Tables["Books"]; }

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  • How to best future proof my application that needs to connect to Outlook?

    - by Troy
    I have a contact management application written in Delphi which has a “Sync with Outlook” feature that I developed 10 years ago. Now, I’m going back to add some features and fix some bugs. This sync feature uses the Outlook object model to get started, but it has an optional mode called “Use MAPI Enhancements” where it uses pure MAPI to speed up how it looks for changes, and it allows notes to be synced w/ RTF instead of just plain text. I'm wondering if supporting two parallel paths of execution is a good idea or not. If I went with all MAPI, I believe I'd avoid some security prompts, and I'd avoid situations where anti-virus has "script-blocking" features which block my app from connecting to Outlook. But I believe that on the down side, my 32-bit app would not be able to to connect with 64-bit Outlook 2010 using MAPI. And I wonder about the future of MAPI in general. If I stick with the Outlook object model, will my 32-bit app be able to connect to the Outlook object model (since it's out of process COM)? If so, this is a compelling reason to keep my Outlook object model execution path in place. But if not, and if my app needs to be compiled for x64, then why not just go with pure MAPI?

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  • Several Objective-C objects become Invalid for no reason, sometimes.

    - by farnsworth
    - (void)loadLocations { NSString *url = @"<URL to a text file>"; NSStringEncoding enc = NSUTF8StringEncoding; NSString *locationString = [[NSString alloc] initWithContentsOfURL:[NSURL URLWithString:url] usedEncoding:&enc error:nil]; NSArray *lines = [locationString componentsSeparatedByString:@"\n"]; for (int i=0; i<[lines count]; i++) { NSString *line = [lines objectAtIndex:i]; NSArray *components = [line componentsSeparatedByString:@", "]; Restaurant *res = [byID objectForKey:[components objectAtIndex:0]]; if (res) { NSString *resAddress = [components objectAtIndex:3]; NSArray *loc = [NSArray arrayWithObjects:[components objectAtIndex:1], [components objectAtIndex:2]]; [res.locationCoords setObject:loc forKey:resAddress]; } else { NSLog([[components objectAtIndex:0] stringByAppendingString:@" res id not found."]); } } } There are a few weird things happening here. First, at the two lines where the NSArray lines is used, this message is printed to the console- *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSCFDictionary count]: method sent to an uninitialized mutable dictionary object' which is strange since lines is definitely not an NSMutableDictionary, definitely is initialized, and because the app doesn't crash. Also, at random points in the loop, all of the variables that the debugger can see will become Invalid. Local variables, property variables, everything. Then after a couple lines they will go back to their original values. setObject:forKey never has an effect on res.locationCoords, which is an NSMutableDictionary. I'm sure that res, res.locationCoords, and byId are initialized. I also tried adding a retain or copy to lines, same thing. I'm sure there's a basic memory management principle I'm missing here but I'm at a loss.

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  • Managing multiple customer databases in ASP.NET MVC application

    - by Robert Harvey
    I am building an application that requires separate SQL Server databases for each customer. To achieve this, I need to be able to create a new customer folder, put a copy of a prototype database in the folder, change the name of the database, and attach it as a new "database instance" to SQL Server. The prototype database contains all of the required table, field and index definitions, but no data records. I will be using SMO to manage attaching, detaching and renaming the databases. In the process of creating the prototype database, I tried attaching a copy of the database (companion .MDF, .LDF pair) to SQL Server, using Sql Server Management Studio, and discovered that SSMS expects the database to reside in c:\program files\Microsoft SQL Server\MSSQL.1\MSSQL\DATA\MyDatabaseName.MDF Is this a "feature" of SQL Server? Is there a way to manage individual databases in separate directories? Or am I going to have to put all of the customer databases in the same directory? (I was hoping for a little better control than this). NOTE: I am currently using SQL Server Express, but for testing purposes only. The production database will be SQL Server 2008, Enterprise version. So "User Instances" are not an option.

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  • Django: How to dynamically add tag field to third party apps without touching app's source code

    - by Chris Lawlor
    Scenario: large project with many third party apps. Want to add tagging to those apps without having to modify the apps' source. My first thought was to first specify a list of models in settings.py (like ['appname.modelname',], and call django-tagging's register function on each of them. The register function adds a TagField and a custom manager to the specified model. The problem with that approach is that the function needs to run BEFORE the DB schema is generated. I tried running the register function directly in settings.py, but I need django.db.models.get_model to get the actual model reference from only a string, and I can't seem to import that from settings.py - no matter what I try I get an ImportError. The tagging.register function imports OK however. So I changed tactics and wrote a custom management command in an otherwise empty app. The problem there is that the only signal which hooks into syncdb is post_syncdb which is useless to me since it fires after the DB schema has been generated. The only other approach I can think of at the moment is to generate and run a 'south' like database schema migration. This seems more like a hack than a solution. This seems like it should be a pretty common need, but I haven't been able to find a clean solution. So my question is: Is it possible to dynamically add fields to a model BEFORE the schema is generated, but more specifically, is it possible to add tagging to a third party model without editing it's source. To clarify, I know it is possible to create and store Tags without having a TagField on the model, but there is a major flaw in that approach in that it is difficult to simultaneously create and tag a new model.

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  • Help with accessing a pre-existing window AFTER opener is refreshed!

    - by Wilhelm Murdoch
    Alright, I'm at my wit's end on this issue. First, backstory. I'm working on a video management system where we're allowing users, when adding new content, to upload and, optionally, transcode a media file. We're using Java applet for the browser-based FTP client. What I want to do is allow a user to initiate an upload and then send the FTP connection instance to a popup window. This window will act as a job queue for the FTP transfer process. This will allow users to move about the main interface without having to stay on the original page until an individual file transfer is complete. For the most part I have all of this working, but here's a problem. If the window is closed, all connections are dropped and the upload process for all queued files will be canceled. So, if Window One opens the Popup Window, adds stuff to the queue, refreshes the screen or moves to a different page, how will I access the Popup Window? The popup window and its contents must remain persistent while the user navigates through the original window. The original window must be able to access the popup to add a new job to the queue. The popup window itself is independent of the opening window, so communication only happens in one direction: Parent - Popup Not Parent <- Popup Window.open(null, 'WINDOW_NAME'); will not work in this case. I need to check if a window exists BEFORE using window.open. Help!?!?

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  • Why Android for enterprise applications?

    - by mcabral
    Recently one of our clients is considering the posibility of picking up an old WinMobile 5.0 project. Several features are to be added to the point it will be a major version update. The client is worried about the mobile market, and thinks there's a chance all the effort put in this development will have to be thrown away in a couple of year due to the dinamics of the mobile market and the deprecation of mobile devices. So, the client is not sure whether he should continue with Windows Mobile (changing from WM 5.0 to 6.X) or starting from scratch with another technology. From our part we have been studing the mobile market, looking for clues for which will be the winning horse. The safe move seems to continue with WM just because re writing an entire application from scratch involves more risks and delays. On the other hand WM seems to be losing market and the ghost of an exit on their part is growing stronger everyday. But what can be say about Android? Everyone is talking about it and is growing at full speed but what avantagies will it bring to the table? Why should we start a fresh applicaction on this technology? So the question remains the same.. is Andriod mature enough for an enterprise application? Will you recomend it to one of your clients? Will you port/rewrite a WM application to Andriod? What's the trade-off? EDIT: Addressing commentaries. The app is entirely built with C# and Compact Framework. The app is for logistics/management.

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  • How to Perform Continues Iteration over Shared Dictionary in Multi-threaded Environment

    - by Mubashar Ahmad
    Dear Gurus. Note Pls do not tell me regarding alternative to custom session, Pls answer only relative to the Pattern Scenario I have Done Custom Session Management in my application(WCF Service) for this I have a Dictionary shared to all thread. When a specific function Gets called I add a New Session and Issue SessionId to the client so it can use that sessionId for rest of his calls until it calls another specific function, which terminates this session and removes the session from the Dictionary. Due to any reason Client may not call session terminator function so i have to implement time expiration logic so that i can remove all such sessions from the memory. For this I added a Timer Object which calls ClearExpiredSessions function after the specific period of time. which iterates on the dictionary. Problem: As this dictionary gets modified every time new client comes and leaves so i can't lock the whole dictionary while iterating over it. And if i do not lock the dictionary while iteration, if dictionary gets modified from other thread while iterating, Enumerator will throw exception on MoveNext(). So can anybody tell me what kind of Design i should follow in this case. Is there any standard pattern available.

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  • Drawbacks with using Class Methods in Objective C.

    - by RickiG
    Hi I was wondering if there are any memory/performance drawbacks, or just drawbacks in general, with using Class Methods like: + (void)myClassMethod:(NSString *)param { // much to be done... } or + (NSArray*)myClassMethod:(NSString *)param { // much to be done... return [NSArray autorelease]; } It is convenient placing a lot of functionality in Class Methods, especially in an environment where I have to deal with memory management(iPhone), but there is usually a catch when something is convenient? An example could be a thought up Web Service that consisted of a lot of classes with very simple functionality. i.e. TomorrowsXMLResults; TodaysXMLResults; YesterdaysXMLResults; MondaysXMLResults; TuesdaysXMLResults; . . . n I collect a ton of these in my Web Service Class and just instantiate the web service class and let methods on this class call Class Methods on the 'Results' Classes. The classes are simple but they handle large amount of Xml, instantiate lots of objects etc. I guess I am asking if Class Methods lives or are treated different on the stack and in memory than messages to instantiated objects? Or are they just instantiated and pulled down again behind the scenes and thus, just a way of saving a few lines of code?

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  • Python on Mac: Fink? MacPorts? Builtin? Homebrew? Binary installer?

    - by BastiBechtold
    For the last few days, I have been trying to use Python for some audio development. The thing is, Mac OSX does not handle uninstalling stuff well. Actually, there is no way to uninstall anything. Once it is on your system, you better pray that it didn't do any funny stuff. Hence, I don't really want to rely on installer packages for Python. So I turn to Homebrew and install Python using Homebrew. Works fabulously. Using pip, Numpy, SciPy, Matplotlib were no (big) problem, either. Now I want to play audio. There is a host of different packages out there, but pip does not seem willing to install any. But, there is a binary distribution for PyGame, which I guess should work with the built-in Python. Hence my question: What would you do? Would you just install the binary distributions and hope that they interoperate well and never need uninstalling? Would you hack your way through whichever package control management system you prefer and deal with its problems? Something else?

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  • how to upgrade compact framework applications?

    - by Derick Bailey
    i'm looking for a way to manage application upgrades for my compact framework app. let's say i have v1 of the app installed on my device, and v1.1 has been released. I want the app to make a call to my server to see if there is a new version. since a new version is found, i want to send down the new version of the app to the device and have it installed, replacing the old version. my first thought was just to have the app download the .cab file and kick off the cab file just before exiting the app. this would mostly get the job done but it would prompt the user to pick the installation location if they have a storage card or other partitions on their device. i would like to prevent any user input and just have the new version of the app installed, replacing the old app. i'm certain that there are others doing this already and i don't want to reinvent the wheel, here. what application management tools and systems exist for this type of process? how can I facilitate this type of process?

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  • DotNetNuke and Subversion guidelines

    - by David Stratton
    I've Googled, Binged, and here at StackOverflow, looked through the related questions and searched, but I'm not finding what I'm looking for. I've also searched documentation on DNN. What I'm looking for is any guidance (tutorials, blogs, step-by-step instructions for setting up a repository) etc from people who are experienced in using DotNetNuke with SVN. We use SVN for all our source control, and have no problem with standard applications, because we pretty much built the repository and directory structure to work with our processes. This means when we do web sites, in Visual Studio, we do file based web sites, rather than setting them up in the local IIS. It just makes things easier for us. However, with DNN, it appears that even if you get the source code, it is expecting to be set up in the local IIS, which means additional headaches for us. For example, we are moving all of our source code off our local C drives, and onto a shared drive on a server. This is to enable backups in addition to our normal source control. (This was a management decision). So that means that we need to change the virtual web app when we make the move. Has anyone come up with a good way to work around this? Can DNN be set up so that the developer web server in Visual Studio can be used, so that we can treat it just like any normal web app? Am I missing something obvious? Edit - added I'm willing to accept answers like "We tried it and never got it to work", and "It can't be done" as answers. I'm always open to hearing "It can't be done the way you want. You need to change your procedures to match how it works" if necessary. I guess if you've got experience trying this and just couldn't get it to work, I can learn from your experience that way as well, but some detail would be good.

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  • Opening my application when a usb device is inserted on Windows using WMI

    - by rsteckly
    Hi, I'm trying to launch an event when someone plugs in a usb device. For now, I'm content to simply print something to the console (in the finished product, it will launch an application). This code is very loosely adapted from: http://serverfault.com/questions/115496/use-wmi-to-detect-a-usb-drive-was-connected-regardless-of-whether-it-was-mounted There's two problems: 1) I need to pass the argument to Management scope dynamically because this will be installed on computers I don't use or whose name I don't know. 2) I'm getting an invalid namespace exception when I call w.Start(); Any ideas what I'm doing wrong? static ManagementEventWatcher w=null; static void Main(string[] args) { AddInstUSBHandler(); for(;;); } public static void USBRemoved(object sneder, EventArgs e) { Console.WriteLine("A USB device inserted"); } static void AddInstUSBHandler() { WqlEventQuery q; ManagementScope scope = new ManagementScope("HQ\\DEV1"); scope.Options.EnablePrivileges=true; q=new WqlEventQuery(); q.EventClassName+="_InstanceCreationEvent"; q.WithinInterval=new TimeSpan(0,0,3); q.Condition=@"TargetInstance ISA 'Win32_USBControllerdevice'"; w=new ManagementEventWatcher(scope,q); w.EventArrived+=new EventArrivedEventHandler(USBRemoved); w.Start(); }

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  • Saving tree-structures in Databases

    - by Nina Null
    Hello everyone. I use Hibernate/Spring and a MySQL Database for my data management. Currently I display a tree-structure in a JTable. A tree can have several branches, in turn a branch can have several branches (up to nine levels) again, or having leaves. Lately I have performanceproblemes, as soon as I want to create new branches on deeper levels. At this time a branch has a foreign key to its parent. The domainobject has access to its parent by calling getParent(), which returns the parent-branch. The deeper the level, the longer it takes to create a new branch. Microbenchmark results for creating a new branch are like: Level 1: 32 ms. Level 3: 80 ms. Level 9: 232 ms. Obviously the level (which means the number of parents) is responsible for this. So I wanted to ask, if there are any appendages to work around this kind of problem. I don’t understand why Hibernate needs to know about the whole object tree (all parents until the root) while creating a new branch. But as far as I know this can be the only reason for the delay while creating a new branch, because a branch doesn’t have any other relations to any other objects. I would be very thankful for any workarounds or suggestions. greets, jambusa

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  • Want to display a 3D model on the iPhone: how to get started?

    - by JeremyReimer
    I want to display and rotate a single 3D model, preferably textured, on the iPhone. Doesn't have to zoom in and out, or have a background, or anything. I have the following: an iPhone a MacBook the iPhone SDK Blender My knowledge base: I can make 3D models in various 3D programs (I'm most comfortable with 3D Studio Max, which I once took a course on, but I've used others) General knowledge of procedural programming from years ago (QuickBasic - I'm old!) Beginner's knowledge of object-oriented programming from going through simple Java and C# tutorials (Head Start C# book and my wife's intro to OOP course that used Java) I have managed to display a 3D textured model and spin it using a tutorial in C# I got off the net (I didn't just copy and paste, I understand basically how it works) and the XNA game development library, using Visual Studio on Windows. What I do not know: Much about Objective C Anything about OpenGL or OpenGL ES, which the iPhone apparently uses Anything about XCode My main problem is that I don't know where to start! All the iPhone books I found seem to be about creating GUI applications, not OpenGL apps. I found an OpenGL book but I don't know how much, if any, applies to iPhone development. And I find the Objective C syntax somewhat confusing, with the weird nested method naming, things like "id" that don't make sense, and the scary thought that I have to do manual memory management. Where is the best place to start? I couldn't find any tutorials for this sort of thing, but maybe my Google-Fu is weak. Or maybe I should start with learning Objective C? I know of books like Aaron Hillgrass', but I've also read that they are outdated and much of the sample code doesn't work on the iPhone SDK, plus it seems geared towards the Model-View-Controller paradigm which doesn't seem that suited for 3D apps. Basically I'm confused about what my first steps should be.

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  • how to implement enhanced session handling in PHP

    - by praksant
    Hi, i'm working with sessions in PHP, and i have different applications on single domain. Problem is, that cookies are domain specific, and so session ids are sent to any page on single domain. (i don't know if there is a way to make cookies work in different way). So Session variables are visible in every page on this domain. I'm trying to implement custom session manager to overcome this behavior, but i'm not sure if i'm thinking about it right. I want to completely avoid PHP session system, and make a global object, which would store session data and on the end of script save it to database. On first access i would generate unique session_id and create a cookie On the end of script save session data with session_id, timestamps for start of session and last access, and data from $_SERVER, such as REMOTE_ADDR, REMOTE_PORT, HTTP_USER_AGENT. On every access chceck database for session_id sent in cookie from client, check IP, Port and user agent (for security) and read data into session variable (if not expired). If session_id expired, delete from database. That session variable would be implemented as singleton (i know i would get tight coupling with this class, but i don't know about better solution). I'm trying to get following benefits: Session variables invisible in another scripts on the same server and same domain Custom management of session expiration Way to see open sessions (something like list of online users) i'm not sure if i'm overlooking any disadvantages of this solution. Is there any better way? Thank you!!

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  • How to generate XML from an Excel VBA macro?

    - by SuperNES
    So, I've got a bunch of content that was delivered to us in the form of Excel spreadsheets. I need to take that content and push it into another system. The other system takes its input from an XML file. I could do all of this by hand (and trust me, management has no problem making me do that!), but I'm hoping there's an easy way to write an Excel macro that would generate the XML I need instead. This seems like a better solution to me, as this is a job that will need to be repeated regularly (we'll be getting a LOT of content in Excel sheets) and it just makes sense to have a batch tool that does it for us. However, I've never experimented with generating XML from Excel spreadsheets before. I have a little VBA knowledge but I'm a newbie to XML. I guess my problem in Googling this is that I don't even know what to Google for. Can anyone give me a little direction to get me started? Does my idea sound like the right way to approach this problem, or am I overlooking something obvious? Thanks StackOverflow!

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  • Security Exception when using Custom ASP.NET Healthmonitoring event in medium trust

    - by Elementenfresser
    Hi, I'm using custom healthmonitoring events in ASP.NET We recently moved to a new server with default High Trust Permissions. Literature says that healthmonitoring and custom events should work under Medium or higher trust (http://msdn.microsoft.com/en-us/library/bb398933.aspx). Problem is - it doesn't. In less than full trust I get a SecurityException saying The application attempted to perform an operation not allowed by the security policy It works in Full trust or when I remove the inheritance of System.Web.Management.WebErrorEvent. Any suggestions anyone? Here is the super simple code behind with a custom event defined: public partial class Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { try { CallCustomEvent(); } catch (Exception ex) { Response.Write(ex.Message); throw ex; } } /// <summary> /// this metho is never called due to lacking permissions... /// </summary> private void CallCustomEvent() { try { //do something useful here } catch (Exception) { //code to instantiate the forbidden inheritance... WebBaseEvent.Raise(new CustomEvent()); } } } /// <summary> /// custom error inheriting WebErrorEvent which is not allowed in high trust? can't believe that... /// </summary> public class CustomEvent : WebErrorEvent { public CustomEvent() : base("test", HttpContext.Current.Request, 100001, new ApplicationException("dummy")) { } } and the Web Config excerpt for high trust: <system.web> <trust level="High" originUrl="" />

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