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• Security review of an authenticated Diffie Hellman variant

  - by mtraut

  EDIT I'm still hoping for some advice on this, i tried to clarify my intentions... When i came upon device pairing in my mobile communication framework i studied a lot of papers on this topic and and also got some input from previous questions here. But, i didn't find a ready to implement protocol solution - so i invented a derivate and as i'm no crypto geek i'm not sure about the security caveats of the final solution: The main questions are Is SHA256 sufficient as a commit function? Is the addition of the shared secret as an authentication info in the commit string safe? What is the overall security of the 1024 bit group DH I assume at most 2^-24 bit probability of succesful MITM attack (because of 24 bit challenge). Is this plausible? What may be the most promising attack (besides ripping the device out off my numb, cold hands) This is the algorithm sketch For first time pairing, a solution proposed in "Key agreement in peer-to-peer wireless networks" (DH-SC) is implemented. I based it on a commitment derived from: A fix "UUID" for the communicating entity/role (128 bit, sent at protocol start, before commitment) The public DH key (192 bit private key, based on the 1024 bit Oakley group) A 24 bit random challenge Commit is computed using SHA256 c = sha256( UUID || DH pub || Chall) Both parties exchange this commitment, open and transfer the plain content of the above values. The 24 bit random is displayed to the user for manual authentication DH session key (128 bytes, see above) is computed When the user opts for persistent pairing, the session key is stored with the remote UUID as a shared secret Next time devices connect, commit is computed by additionally hashing the previous DH session key before the random challenge. For sure it is not transfered when opening. c = sha256( UUID || DH pub || DH sess || Chall) Now the user is not bothered authenticating when the local party can derive the same commitment using his own, stored previous DH session key. After succesful connection the new DH session key becomes the new shared secret. As this does not exactly fit the protocols i found so far (and as such their security proofs), i'd be very interested to get an opinion from some more crypto enabled guys here. BTW. i did read about the "EKE" protocol, but i'm not sure what the extra security level is.

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• How do I 'globally' catch exceptions thrown in object instances.

  - by SleepyBobos

  I am currently writing a winforms application (C#). I am making use of the Enterprise Library Exception Handling Block, following a fairly standard approach from what I can see. IE : In the Main method of Program.cs I have wired up event handler to Application.ThreadException event etc. This approach works well and handles the applications exceptional circumstances. In one of my business objects I throw various exceptions in the Set accessor of one of the objects properties set { if (value > MaximumTrim) throw new CustomExceptions.InvalidTrimValue("The value of the minimum trim..."); if (!availableSubMasterWidthSatisfiesAllPatterns(value)) throw new CustomExceptions.InvalidTrimValue("Another message..."); _minimumTrim = value; } My logic for this approach (without turning this into a 'when to throw exceptions' discussion) is simply that the business objects are responsible for checking business rule constraints and throwing an exception that can bubble up and be caught as required. It should be noted that in the UI of my application I do explictly check the values that the public property is being set to (and take action there displaying friendly dialog etc) but with throwing the exception I am also covering the situation where my business object may not be used by a UI eg : the Property is being set by another business object for example. Anyway I think you all get the idea. My issue is that these exceptions are not being caught by the handler wired up to Application.ThreadException and I don't understand why. From other reading I have done the Application.ThreadException event and it handler "... catches any exception that occurs on the main GUI thread". Are the exceptions being raised in my business object not in this thread? I have not created any new threads. I can get the approach to work if I update the code as follows, explicity calling the event handler that is wired to Application.ThreadException. This is the approach outlined in Enterprise Library samples. However this approach requires me to wrap any exceptions thrown in a try catch, something I was trying to avoid by using a 'global' handler to start with. try { if (value > MaximumTrim) throw new CustomExceptions.InvalidTrimValue("The value of the minimum..."); if (!availableSubMasterWidthSatisfiesAllPatterns(value)) throw new CustomExceptions.InvalidTrimValue("Another message"); _minimumTrim = value; } catch (Exception ex) { Program.ThreadExceptionHandler.ProcessUnhandledException(ex); } I have also investigated using wiring a handler up to AppDomain.UnhandledException event but this does not catch the exceptions either. I would be good if someone could explain to me why my exceptions are not being caught by my global exception handler in the first code sample. Is there another approach I am missing or am I stuck with wrapping code in try catch, shown above, as required?

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• How to infer the type of a derived class in base class?

  - by enzi

  I want to create a method that allows me to change arbitrary properties of classes that derive from my base class, the result should look like this: SetPropertyValue("size.height", 50); – where size is a property of my derived class and height is a property of size. I'm almost done with my implementation but there's one final obstacle that I want to solve before moving on, to describe this I will first have to explain my implementation a bit: Properties that can be modified are decorated with an attribute There's a method in my base class that searches for all derived classes and their decorated properties For each property I generate a "property modifier", a class that contains 2 delegates: one to set and one to get the value of the property. Property Modifiers are stored in a dictionary, with the name of the property as key In my base class, there is another dictionary that contains all property-modifier-dictionaries, with the Type of the respective class as key. What the SetPropertyValue method does is this: Get the correct property-modifier-dictionary, using the concrete type of the derived class (<- yet to solve) Get the property modifier of the property to change (e.g. of the property size) Use the get or set delegate to modify the property's value Some example code to clarify further: private static Dictionary<RuntimeTypeHandle, object> EditableTypes; //property-modifier-dictionary protected void SetPropertyValue<T>(EditablePropertyMap<T> map, string property, object value) { var property = map[property]; // get the property modifier property.Set((T)this, value); // use the set delegate (encapsulated in a method) } In the above code, T is the Type of the actual (derived) class. I need this type for the get/set delegates. The problem is how to get the EditablePropertyMap<T> when I don't know what T is. My current (ugly) solution is to pass the map in an overriden virtual method in the derived class: public override void SetPropertyValue(string property, object value) { base.SetPropertyValue((EditablePropertyMap<ExampleType>)EditableTypes[typeof(ExampleType)], property, value); } What this does is: get the correct dictionary containing the property modifiers of this class using the class's type, cast it to the appropiate type and pass it to the SetPropertyValue method. I want to get rid of the SetPropertyValue method in my derived class (since there are a lot of derived classes), but don't know yet how to accomplish that. I cannot just make a virtual GetEditablePropertyMap<T> method because I cannot infer a concrete type for T then. I also cannot acces my dictionary directly with a type and retrieve an EditablePropertyMap<T> from it because I cannot cast to it from object in the base class, since again I do not know T. I found some neat tricks to infere types (e.g. by adding a dummy T parameter), but cannot apply them to my specific problem. I'd highly appreciate any suggestions you may have for me.

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• How to approach copying objects with smart pointers as class attributes?

  - by tomislav-maric

  From the boost library documentation I read this: Conceptually, smart pointers are seen as owning the object pointed to, and thus responsible for deletion of the object when it is no longer needed. I have a very simple problem: I want to use RAII for pointer attributes of a class that is Copyable and Assignable. The copy and assignment operations should be deep: every object should have its own copy of the actual data. Also, RTTI needs to be available for the attributes (their type may also be determined at runtime). Should I be searching for an implementation of a Copyable smart pointer (the data are small, so I don't need Copy on Write pointers), or do I delegate the copy operation to the copy constructors of my objects as shown in this answer? Which smart pointer do I choose for simple RAII of a class that is copyable and assignable? (I'm thinking that the unique_ptr with delegated copy/assignment operations to the class copy constructor and assignment operator would make a proper choice, but I am not sure) Here's a pseudocode for the problem using raw pointers, it's just a problem description, not a running C++ code: // Operation interface class ModelOperation { public: virtual void operate = (); }; // Implementation of an operation called Special class SpecialModelOperation : public ModelOperation { private: // Private attributes are present here in a real implementation. public: // Implement operation void operate () {}; }; // All operations conform to ModelOperation interface // These are possible operation names: // class MoreSpecialOperation; // class DifferentOperation; // Concrete model with different operations class MyModel { private: ModelOperation* firstOperation_; ModelOperation* secondOperation_; public: MyModel() : firstOperation_(0), secondOperation_(0) { // Forgetting about run-time type definition from input files here. firstOperation_ = new MoreSpecialOperation(); secondOperation_ = new DifferentOperation(); } void operate() { firstOperation_->operate(); secondOperation_->operate(); } ~MyModel() { delete firstOperation_; firstOperation_ = 0; delete secondOperation_; secondOperation_ = 0; } }; int main() { MyModel modelOne; // Some internal scope { // I want modelTwo to have its own set of copied, not referenced // operations, and at the same time I need RAII to work for it, // as soon as it goes out of scope. MyModel modelTwo (modelOne); } return 0; }

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• Parsing CSV File to MySQL DB in PHP

  - by Austin

  I have a some 350-lined CSV File with all sorts of vendors that fall into Clothes, Tools, Entertainment, etc.. categories. Using the following code I have been able to print out my CSV File. <?php $fp = fopen('promo_catalog_expanded.csv', 'r'); echo '<tr><td>'; echo implode('</td><td>', fgetcsv($fp, 4096, ',')); echo '</td></tr>'; while(!feof($fp)) { list($cat, $var, $name, $var2, $web, $var3, $phone,$var4, $kw,$var5, $desc) = fgetcsv($fp, 4096); echo '<tr><td>'; echo $cat. '</td><td>' . $name . '</td><td><a href="http://www.' . $web .'" target="_blank">' .$web.'</a></td><td>'.$phone.'</td><td>'.$kw.'</td><td>'.$desc.'</td>' ; echo '</td></tr>'; } fclose($file_handle); show_source(__FILE__); ?> First thing you will probably notice is the extraneous vars within the list(). this is because of how the excel spreadsheet/csv file: Category,,Company Name,,Website,,Phone,,Keywords,,Description ,,,,,,,,,, Clothes,,4imprint,,4imprint.com,,877-466-7746,,"polos, jackets, coats, workwear, sweatshirts, hoodies, long sleeve, pullovers, t-shirts, tees, tshirts,",,An embroidery and apparel company based in Wisconsin. ,,Apollo Embroidery,,apolloemb.com,,1-800-982-2146,,"hats, caps, headwear, bags, totes, backpacks, blankets, embroidery",,An embroidery sales company based in California. One thing to note is that the last line starts with two commas as it is also listed within "Clothes" category. My concern is that I am going about the CSV output wrong. Should I be using a foreach loop instead of this list way? Should I first get rid of any unnecessary blank columns? Please advise any flaws you may find, improvements I can use so I can be ready to import this data to a MySQL DB.

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• Abnormally disconnected TCP sockets and write timeout

  - by James

  Hello I will try to explain the problem in shortest possible words. I am using c++ builder 2010. I am using TIdTCPServer and sending voice packets to a list of connected clients. Everything works ok untill any client is disconnected abnormally, For example power failure etc. I can reproduce similar disconnect by cutting the ethernet connection of a connected client. So now we have a disconnected socket but as you know it is not yet detected at server side so server will continue to try to send data to that client too. But when server try to write data to that disconnected client ...... Write() or WriteLn() HANGS there in trying to write, It is like it is wating for somekind of Write timeout. This hangs the hole packet distribution process as a result creating a lag in data transmission to all other clients. After few seconds "Socket Connection Closed" Exception is raised and data flow continues. Here is the code try { EnterCriticalSection(&SlotListenersCriticalSection); for(int i=0;i<SlotListeners->Count;i++) { try { //Here the process will HANG for several seconds on a disconnected socket ((TIdContext*) SlotListeners->Objects[i])->Connection->IOHandler->WriteLn("Some DATA"); }catch(Exception &e) { SlotListeners->Delete(i); } } }__finally { LeaveCriticalSection(&SlotListenersCriticalSection); } Ok i already have a keep alive mechanism which disconnect the socket after n seconds of inactivity. But as you can imagine, still this mechnism cant sync exactly with this braodcasting loop because this braodcasting loop is running almost all the time. So is there any Write timeouts i can specify may be through iohandler or something ? I have seen many many threads about "Detecting disconnected tcp socket" but my problem is little different, i need to avoid that hangup for few seconds during the write attempt. So is there any solution ? Or should i consider using some different mechanism for such data broadcasting for example the broadcasting loop put the data packet in some kind of FIFO buffer and client threads continuously check for available data and pick and deliver it to themselves ? This way if one thread hangs it will not stop/delay the over all distribution thread. Any ideas please ? Thanks for your time and help. Regards Jams

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• Remove Item From Object SubList (LINQ)

  - by X3074861X

  I have an object that looks like this : public class Consortium { public string Id { get; set; } [JsonConverter(typeof(EnumDescriptionConverter))] public SourceType Type { get; set; } public List<UserLibrary> Branches { get; set; } } Each Consortium has a list of UserLibrary's associated with it, and that class looks like this : public class UserLibrary { public string LibraryId { get; set; } public string RetailerId {get; set;} public string UserId { get; set; } public string Name { get; set; } public DateTime CreatedAt { get; set; } } I have a method which will allow the user to remove a library from one of their consortium (note: There may be many branches associated to the consortium). However, I'm only being supplied a LibraryId, so I'm forced to traverse their list of Consortium, find which one contains the given id, then iterate over the branches and remove the one that matches the id. Here is how I'm currently accomplishing this : // Get the current list of consortiums var user = _mediator.Send(new GetUserProfileCommand { UserProfileId = _principle.UserProfileId }); var userConsortia = user.SavedConsortia; // the consortium to remove the library from var branchToRemove = _libraryService.GetLibrary(id); var consortRemove = new UserConsortium(); foreach (var userConsortium in userConsortia) { if (userConsortium.Branches.FirstOrDefault(c => string.Equals(c.LibraryId, id, StringComparison.OrdinalIgnoreCase)) != null) { consortRemove = userConsortium; } } // if the consortium id is null, something is f* if (consortRemove.Id == null) { return new JsonDotNetResult(HttpStatusCode.BadRequest); } // first remove the consortia userConsortia.Remove(consortRemove); // remove the branch from the consortium consortRemove.Branches.RemoveAll(ul => string.Equals(ul.LibraryId, id, StringComparison.OrdinalIgnoreCase)); // add it back in without the branch userConsortia.Add(consortRemove); Question : Is there a LINQ expression I'm missing here that can help me consolidate this logic, or is there a better way of doing this?

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• Load/Store Objects in file in Java

  - by brain_damage

  I want to store an object from my class in file, and after that to be able to load the object from this file. But somewhere I am making a mistake(s) and cannot figure out where. May I receive some help? public class GameManagerSystem implements GameManager, Serializable { private static final long serialVersionUID = -5966618586666474164L; HashMap<Game, GameStatus> games; HashMap<Ticket, ArrayList<Object>> baggage; HashSet<Ticket> bookedTickets; Place place; public GameManagerSystem(Place place) { super(); this.games = new HashMap<Game, GameStatus>(); this.baggage = new HashMap<Ticket, ArrayList<Object>>(); this.bookedTickets = new HashSet<Ticket>(); this.place = place; } public static GameManager createManagerSystem(Game at) { return new GameManagerSystem(at); } public boolean store(File f) { try { FileOutputStream fos = new FileOutputStream(f); ObjectOutputStream oos = new ObjectOutputStream(fos); oos.writeObject(games); oos.writeObject(bookedTickets); oos.writeObject(baggage); oos.close(); fos.close(); } catch (IOException ex) { return false; } return true; } public boolean load(File f) { try { FileInputStream fis = new FileInputStream(f); ObjectInputStream ois = new ObjectInputStream(fis); this.games = (HashMap<Game,GameStatus>)ois.readObject(); this.bookedTickets = (HashSet<Ticket>)ois.readObject(); this.baggage = (HashMap<Ticket,ArrayList<Object>>)ois.readObject(); ois.close(); fis.close(); } catch (IOException e) { return false; } catch (ClassNotFoundException e) { return false; } return true; } . . . } public class JUnitDemo { GameManager manager; @Before public void setUp() { manager = GameManagerSystem.createManagerSystem(Place.ENG); } @Test public void testStore() { Game g = new Game(new Date(), Teams.LIONS, Teams.SHARKS); manager.registerGame(g); File file = new File("file.ser"); assertTrue(airport.store(file)); } }

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• How to discover classes with [Authorize] attributes using Reflection in C#? (or How to build Dynamic

  - by Pretzel

  Maybe I should back-up and widen the scope before diving into the title question... I'm currently writing a web app in ASP.NET MVC 1.0 (although I do have MVC 2.0 installed on my PC, so I'm not exactly restricted to 1.0) -- I've started with the standard MVC project which has your basic "Welcome to ASP.NET MVC" and shows both the [Home] tab and [About] tab in the upper-right corner. Pretty standard, right? I've added 4 new Controller classes, let's call them "Astronomer", "Biologist", "Chemist", and "Physicist". Attached to each new controller class is the [Authorize] attribute. For example, for the BiologistController.cs [Authorize(Roles = "Biologist,Admin")] public class BiologistController : Controller { public ActionResult Index() { return View(); } } These [Authorize] tags naturally limit which user can access different controllers depending on Roles, but I want to dynamically build a Menu at the top of my website in the Site.Master Page based on the Roles the user is a part of. So for example, if JoeUser was a member of Roles "Astronomer" and "Physicist", the navigation menu would say: [Home] [Astronomer] [Physicist] [About] And naturally, it would not list links to "Biologist" or "Chemist" controller Index page. Or if "JohnAdmin" was a member of Role "Admin", links to all 4 controllers would show up in the navigation bar. Ok, you prolly get the idea... Starting with the answer from this StackOverflow topic about Dynamic Menu building in ASP.NET, I'm trying to understand how I would fully implement this. (I'm a newbie and need a little more guidance, so please bare with me.) The answer proposes Extending the Controller class (call it "ExtController") and then have each new WhateverController inherit from ExtController. My conclusion is that I would need to use Reflection in this ExtController Constructor to determine which Classes and Methods have [Authorize] attributes attached to them to determine the Roles. Then using a Static Dictionary, store the Roles and Controllers/Methods in key-value pairs. I imagine it something like this: public class ExtController : Controller { protected static Dictionary<Type,List<string>> ControllerRolesDictionary; protected override void OnActionExecuted(ActionExecutedContext filterContext) { // build list of menu items based on user's permissions, and add it to ViewData IEnumerable<MenuItem> menu = BuildMenu(); ViewData["Menu"] = menu; } private IEnumerable<MenuItem> BuildMenu() { // Code to build a menu SomeRoleProvider rp = new SomeRoleProvider(); foreach (var role in rp.GetRolesForUser(HttpContext.User.Identity.Name)) { } } public ExtController() { // Use this.GetType() to determine if this Controller is already in the Dictionary if (!ControllerRolesDictionary.ContainsKey(this.GetType())) { // If not, use Reflection to add List of Roles to Dictionary // associating with Controller } } } Is this doable? If so, how do I perform Reflection in the ExtController constructor to discover the [Authorize] attribute and related Roles (if any) ALSO! Feel free to go out-of-scope on this question and suggest an alternate way of solving this "Dynamic Site.Master Menu based on Roles" problem. I'm the first to admit that this may not be the best approach.

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• xstream handles non-english character

  - by Yan Cheng CHEOK

  I have the following code : /* * To change this template, choose Tools | Templates * and open the template in the editor. */ package helloworld; import com.thoughtworks.xstream.XStream; import java.io.File; import java.io.FileOutputStream; import java.io.InputStream; import java.io.OutputStream; import javax.swing.JOptionPane; /** * * @author yccheok */ public class Test { @SuppressWarnings("unchecked") public static <A> A fromXML(Class c, File file) { XStream xStream = new XStream(); InputStream inputStream = null; try { inputStream = new java.io.FileInputStream(file); Object object = xStream.fromXML(inputStream); if (c.isInstance(object)) { return (A)object; } } catch (Exception exp) { exp.printStackTrace(); } finally { if (inputStream != null) { try { inputStream.close(); inputStream = null; } catch (java.io.IOException exp) { exp.printStackTrace(); return null; } } } return null; } @SuppressWarnings("unchecked") public static <A> A fromXML(Class c, String filePath) { return (A)fromXML(c, new File(filePath)); } public static boolean toXML(Object object, File file) { XStream xStream = new XStream(); OutputStream outputStream = null; try { outputStream = new FileOutputStream(file); xStream.toXML(object, outputStream); } catch (Exception exp) { exp.printStackTrace(); return false; } finally { if (outputStream != null) { try { outputStream.close(); outputStream = null; } catch (java.io.IOException exp) { exp.printStackTrace(); return false; } } } return true; } public static boolean toXML(Object object, String filePath) { return toXML(object, new File(filePath)); } public static void main(String args[]) { String s = "\u6210\u4EA4\u91CF"; // print ??? System.out.println(s); // fine! show ??? JOptionPane.showMessageDialog(null, s); toXML(s, "C:\\A.XML"); String o = fromXML(String.class, "C:\\A.XML"); // show ??? JOptionPane.showMessageDialog(null, o); } } I run the following code through command prompt in Windows Vista. 1) May I know why System.out.println unable to print out Chinese Character in console? 2) I open up the xstream file. The saved value is <string>???</string> How can I make xstream save Chinese Character correctly? Thanks.

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• How to use JSON response in the form of JSTL?

  - by HariKrishna

  I am getting JSON response,now i need to construct a table using this response.The table may be contain more than one record and i know one way of doing this is using Jstl tags but not JSON response.Here is my jsp code <div id="divHideAllergies" class="clone"> <div class="copy"> <div class="col-md-12"> <div class="portlet box carrot "> <div class="portlet-title"> <div class="caption"> <i class="fa fa-medkit"></i> Allergies </div> </div> <div class="portlet-body form"> <div class="form-body"> <div class="form-group"> <label class="control-label col-md-3">Allergy Type:</label> <div class="col-md-9"> <div class="input-group"> <span class="input-group-addon"><i class="fa fa-medkit"></i></span> <select class="form-control" id="allergy_type"> <option selected value="">--Select One--</option> <option value="Drug">Drug</option> <option value="Environmental">Environmental</option <option value="Food">Food</option> </select> </div> </div> </div> <div class="form-group"> <label class="control-label col-md-3">Allergic to:</label> <div class="col-md-9"> <div class="input-group"> <span class="input-group-addon"><i class="fa fa-medkit"></i></span> <input type="text" class="form-control" name="first name" id="allergy_to"/> </div> </div> </div> </div> </div> </div> </div> </div> </div> </div>

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• XML serialization options in .NET

  - by Borek

  I'm building a service that returns an XML (no SOAP, no ATOM, just plain old XML). Say that I have my domain objects already filled with data and just need to transform them to the XML format. What options do I have on .NET? Requirements: The transformation is not 1:1. Say that I have an Address property of type Address with nested properties like Line1, City, Postcode etc. This may need to result in an XML like <xaddr city="...">Line1, Postcode</xaddr>, i.e. quite different. Some XML elements/attributes are conditional, for example, if a Customer is under 18, the XML needs to contain some additional information. I only need to serialize the objects to XML, the other direction (XML to objects) is not important Some technologies, i.e. Data Contracts use .NET attributes. Other means of configuration (external XML config, buddy classes etc.) would be a plus. Here are the options as I see them as the moment. Corrections / additions will be very welcome. String concatenation - forget it, it was a joke :) Linq 2 XML - complete control but quite a lot of hand written code, would need good suite of unit tests View engines in ASP.NET MVC (or even Web Forms theoretically), the logic being in controllers. It's a question how to structure it, I can have simple rules engine in my controller(s) and one view template per each possible output, or have the decision logic directly in the template. Both have upsides and downsides. XML Serialization - I'm not sure about the flexibility here Data Contracts from WCF - not sure about the flexibility either, plus would they work in a simple ASP.NET MVC app (non-WCF service)? Are they a super-set of the standard XML serialization now? If it exists, some XML-to-object mapper. The more I think about it the more I think I'm looking for something like this but I couldn't find anything appropriate. Any comments / other options?

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• C - What is the proper format to allow a function to show an error was encountered?

  - by BrainSteel

  I have a question about what a function should do if the arguments to said function don't line up quite right, through no fault of the function call. Since that sentence doesn't make much sense, I'll offer my current issue. To keep it simple, here is the most relevant and basic function I have. float getYValueAt(float x, PHYS_Line line, unsigned short* error) *error = 0; if(x < line.start.x || x > line.end.x){ *error = 1; return -1; } if(line.slope.value != 0){ //line's equation: y - line.start.y = line.slope.value(x - line.start.x) return line.slope.value * (x - line.start.x) + line.start.y; } else if(line.slope.denom == 0){ if(line.start.x == x) return line.start.y; else{ *error = 1; return -1; } } else if(line.slope.num == 0){ return line.start.y; } } The function attempts to find the point on a line, given a certain x value. However, under some circumstances, this may not be possible. For example, on the line x = 3, if 5 is passed as a value, we would have a problem. Another problem arises if the chosen x value is not within the interval the line is on. For this, I included the error pointer. Given this format, a function call could work as follows: void foo(PHYS_Line some_line){ unsigned short error = 0; float y = getYValueAt(5, some_line, &error); if(error) fooey(); else do_something_with_y(y); } My question pertains to the error. Note that the value returned is allowed to be negative. Returning -1 does not ensure that an error has occurred. I know that it is sometimes preferred to use the following method to track an error: float* getYValueAt(float x, PHYS_Line line); and then return NULL if an error occurs, but I believe this requires dynamic memory allocation, which seems even less sightly than the solution I was using. So, what is standard practice for an error occurring?

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• How do you remind your Scrum Product Owner about his promises/actions?

  - by Felix Ogg

  ** EDIT: Rephrased the question to re-focus ** Our Scrum team meets as seldomly as possible, but we meet with the product owner every chance we get. We track everyone's agreed action points (particularly theirs). We are 100% agile, but our product owner lives in traditional world, we remain off-site. We facilitate him in crossing over to our fast-paced world. There's not much wrong. The team and the PO are in good spirits. PO is present at every meeting and positively energized. Just imagine this person as a 70 year old, slow grandpa, who is forgetful, yet kind. In reality he isn't, but he is used to a working environment (public servants) that is much slooooower. Manyana-manyana etc. It is frustrating for my team to cooperate: PO lives in a non-prioritized environment, and everyone in it has learned the productivity-technique of NGTD (Not Getting Things Done). He WANTS to, it's just that he forgets or 'sinks' somewhere along the away. We have experimented with a text file, maintained by the Scrum master (low-tech), which he broadcasts by e-mail every day JIRA, our issue tracker. Turns out this is nice for programmers, but too steep for 'regular people' I Googled for Issue tracking webtools but came up empty handed: All tools are aimed at IT issue tracking, instead of meeting action point tracking/planning for mere mortals. I did find TODO-lists like RememberTheMilk, but they don't track comments, and - to be honest - I doubt we could get our product owner to use it (too complicated). We have three requirements: Register action points, assign to a team member and a deadline Offer anyone to 'comment' on progress of any action point Do not build our own tool from scratch We do not need: - impressive authorization models, - multi-project, - workflow, - crosslinking. Is there any trick/tool you use to assist your product owner 'fly' like the rest of the rest of the team? Communication before tools I agree with the general consensus that one should not try to apply technology to a communication problem, however in this case I am merely looking for a tool to save me time in setting up prioritized lists. I found www.thymer.com today, may be what I am looking for. The guys are cool. It is getting rather feature-bloated though.

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• Best approach for using Scanner Objects in Java?

  - by devjeetroy

  Although I'm more of a C++/ASM guy, I have to work with java as a part of my undergrad course at college. Our teacher taught us input using Scanner(System.in), and told us that if multiple functions are were taking user input, it would be advisable that a single Scanner object is passed around so as to reduce chances of the input stream getting screwed up. Now using this approach has gotten me into a situation where I'm trying to use a Scanner.nextLine(), and this statement does not wait for user input. It just moves on to the following statement. I figured there may be some residual cr/lf or other characters in the Scanner that might not have been retrieved are causing the problem. Here is the code. while(lineScanner.hasNext()) { if(isPlaceHolder(temp = lineScanner.next())) { temp = temp.replace("<",""); temp = temp.replace(">", ""); System.out.print("Enter "+aOrA(temp.charAt(0)) +" " +temp + " : "); temp = consoleInput.nextLine(); } outputFileStream.print(temp + " "); } All of the code is inside a function which receives a Scanner object consoleInput. Ok, so what happens when i run it is that when the program enters the if() the first time, It carries out theSystem.out.print, does not wait for user input, and moves on to the second time that it enters the 'if' block. This time, it takes the input and the rest of the program operates normally. What is even more surprising is that when i check the output file created by the program, it is perfect, just as i want to be. Almost as if the first time input using the scanner is correct. I have solved this problem by creating a new system.in Scanner in the function itself, instead of receiving the Scanner object as a parameter. But I am still very curious to know what the hell is happening and why it couldn't be solved using a simple Scanner.reset(). Would it be better to just simply create a Scanner Object for each function? Thanks, Devjeet PS. Although I know how to take input using fileinputstreams and the like, we are not supposed to use it with the homework.

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• MVC EditorFor bind to type in array

  - by BradBrening

  I have a ViewModel that, among other properties, contains an array of 'EmailAddress' objects. EmailAddress itself has properties such as "Address", and "IsPrimary". My view model breakdown is: public class UserDetailsViewModel { public BUser User { get; set; } public string[] Roles { get; set; } public EmailAddress[] EmailAddresses { get; set; } } I am showing a "User Details" page that is pretty standard. For example, I'm displaying data using @Html.DisplayFor(model => model.User.UserName) and @Html.DisplayFor(model => model.User.Comment) I also have a section on the page that lists all of the EmailAddress objects associated with the user: @if(Model.EmailAddresses.Length > 0) { foreach (var address in Model.EmailAddresses) { <div> @Html.DisplayFor(model => address.Address) </div> } } else { <div class="center">User does not have any email addresses.</div> } My problem is that I would like to show an "Add Email Address" form above the list of email addresses. I thought I would take the "normal" approach thusly: @using(Html.BeginForm(new { id=Model.User.UserName, action="AddUserEmailAddress" })) { <text>Address:</text> @Html.EditorFor(model => ** HERE I AM STUCK **) <input type="submit" value="Add Email" class="button" /> } As you may be able to tell, I am stuck here. I've tried model => Model.EmailAddresses[0] and model => Model.EmailAddresses.FirstOrDefault(). Both of these have failed horribly. I am sure that I am going about this all wrong. I've even thought of adding a "dummy" property to my ViewModel of type EmailAddress just so that I can bind to that in my EditorFor - but that seems to be a really bad hack. There has to be something simple that I'm overlooking! I would appreciate any help anyone can offer with this matter. Thank you in advance!

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• Race condition for thread startup

  - by Ozzah

  A similar question was asked here, but the answers generally all seem to relate to the lambda notation. I get a similar result without the lambda so I thought I'd ask for some clarification: Say I have something like this: for (int i = 0; i < 5; i++) (new Thread(new ThreadStart(delegate() { Console.WriteLine("Thread " + i); }))).Start(); One would expect the following output: Thread 0 Thread 1 Thread 2 Thread 3 Thread 4 Now I realise that the threads aren't started in any particular order, so let's just assume that the above lines can come out in any order. But that is not what happens. What instead happens: Thread 3 Thread 4 Thread 4 Thread 4 Thread 4 or something similar, which leads me to believe that rather than passing the value if i, it is passing the reference. (Which is weird, since an int is a value type). Doing something like this: for (int i = 0; i < 5; i++) (new Thread(new ThreadStart(delegate() { int j = i; Console.WriteLine("Thread " + j); }))).Start(); does not help either, even though we have made a copy of i. I am assuming the reason is that it hasn't made a copy of i in time. Doing something like this: for (int i = 0; i < 5; i++) { (new Thread(new ThreadStart(delegate() { Console.WriteLine("Thread " + i); }))).Start(); Thread.Sleep(50); } seems to fix the problem, however it is extremely undesirable as we're wasting 50ms on each iteration, not to mention the fact that if the computer is heavily loaded then maybe 50ms may not be enough. Here is a sample with my current, specific problem: Thread t = new Thread(new ThreadStart(delgate() { threadLogic(param1, param2, param3, param4); })); t.Start(); param1 = param2 = param3 = param4 = null; with: void threadLogic(object param1, object param2, object param3, object param4) { // Do some stuff here... } I want threadLogic() to run in its own thread, however the above code gives a null reference exception. I assume this is because the values are set to null before the thread has had a chance to start. Again, putting a Thread.Sleep(100) works, but it is an awful solution from every aspect. What do you guys recommend for this particular type of race condition?

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• CultureManager issue

  - by Serge

  I have a bug I don't understand. While the following works fine: Resources.Classes.AFieldFormula.DirectFieldFormula this one throws an exception: new ResourceManager(typeof(Resources.Classes.AFieldFormula)).GetString("DirectFieldFormula"); Could not find any resources appropriate for the specified culture or the neutral culture. Make sure \"Resources.Classes.AFieldFormula.resources\" was correctly embedded or linked into assembly \"MygLogWeb\" at compile time, or that all the satellite assemblies required are loadable and fully signed. How comes? Resource designer.cs file: //------------------------------------------------------------------------------ // <auto-generated> // This code was generated by a tool. // Runtime Version:4.0.30319.18408 // // Changes to this file may cause incorrect behavior and will be lost if // the code is regenerated. // </auto-generated> //------------------------------------------------------------------------------ namespace Resources.Classes { using System; /// <summary> /// A strongly-typed resource class, for looking up localized strings, etc. /// </summary> // This class was auto-generated by the StronglyTypedResourceBuilder // class via a tool like ResGen or Visual Studio. // To add or remove a member, edit your .ResX file then rerun ResGen // with the /str option, or rebuild your VS project. [global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Resources.Tools.StronglyTypedResourceBuilder", "4.0.0.0")] [global::System.Diagnostics.DebuggerNonUserCodeAttribute()] [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()] public class AFieldFormula { private static global::System.Resources.ResourceManager resourceMan; private static global::System.Globalization.CultureInfo resourceCulture; [global::System.Diagnostics.CodeAnalysis.SuppressMessageAttribute("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")] internal AFieldFormula() { } /// <summary> /// Returns the cached ResourceManager instance used by this class. /// </summary> [global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Advanced)] public static global::System.Resources.ResourceManager ResourceManager { get { if (object.ReferenceEquals(resourceMan, null)) { global::System.Resources.ResourceManager temp = new global::System.Resources.ResourceManager("MygLogWeb.Classes.AFieldFormula", typeof(AFieldFormula).Assembly); resourceMan = temp; } return resourceMan; } } /// <summary> /// Overrides the current thread's CurrentUICulture property for all /// resource lookups using this strongly typed resource class. /// </summary> [global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Advanced)] public static global::System.Globalization.CultureInfo Culture { get { return resourceCulture; } set { resourceCulture = value; } } /// <summary> /// Looks up a localized string similar to Direct field. /// </summary> public static string DirectFieldFormula { get { return ResourceManager.GetString("DirectFieldFormula", resourceCulture); } } } }

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• Passing an array of an array of char to a function

  - by L.A. Rabida

  In my program, I may need to load a large file, but not always. So I have defined: char** largefilecontents; string fileName="large.txt"; When I need to load the file, the program calles this function: bool isitok=LoadLargeFile(fileName,largefilecontents); And the function is: bool LoadLargeFile(string &filename, char ** &lines) { if (lines) delete [] lines; ifstream largeFile; #ifdef LINUX largeFile.open(filename.c_str()); #endif #ifdef WINDOWS largeFile.open(filename.c_str(),ios::binary); #endif if (!largeFile.is_open()) return false; lines=new char *[10000]; if (!lines) return false; largeFile.clear(); largeFile.seekg(ios::beg); for (int i=0; i>-1; i++) { string line=""; getline(largeFile,line); if (largeFile.tellg()==-1) break; //when end of file is reached, tellg returns -1 lines[i]=new char[line.length()]; lines[i]=const_cast<char*>(line.c_str()); cout << lines[i] << endl; //debug output } return true; } When I view the debug output of this function, "cout << lines[i] << endl;", it is fine. But when I then check this in the main program like this, it is all messed up: for (i=0; i<10000; i++) cout << largefilecontents[i] << endl; So within the function LoadLargeFile(), the results are fine, but without LoadLargeFile(), the results are all messed up. My guess is that the char ** &lines part of the function isn't right, but I do not know what this should be. Could someone help me? Thank you in advance!

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• First record does not show in pagination script

  - by whitstone86

  This is my pagination script which extracts info for my TV guide project that I am working on. Currently I've been experimenting with different PHP/MySQL before it becomes a production site. This is my current script: <?php /*********************************** * PhpMyCoder Paginator * * Created By PhpMyCoder * * 2010 PhpMyCoder * * ------------------------------- * * You may use this code as long * * as this notice stays intact and * * the proper credit is given to * * the author. * ***********************************/ // set the default timezone to use. Available since PHP 5.1 putenv("TZ=US/Eastern") ?> <head> <title> Pagination Test - Created By PhpMyCoder</title> <style type="text/css"> #nav { font: normal 13px/14px Arial, Helvetica, sans-serif; margin: 2px 0; } #nav a { background: #EEE; border: 1px solid #DDD; color: #000080; padding: 1px 7px; text-decoration: none; } #nav strong { background: #000080; border: 1px solid #DDD; color: #FFF; font-weight: normal; padding: 1px 7px; } #nav span { background: #FFF; border: 1px solid #DDD; color: #999; padding: 1px 7px; } </style> </head> <?php //Require the file that contains the required classes include("pmcPagination.php"); //PhpMyCoder Paginator $paginator = new pmcPagination(20, "page"); //Connect to the database mysql_connect("localhost","root","PASSWORD"); //Select DB mysql_select_db("mytvguide"); //Select only results for today and future $result = mysql_query("SELECT programme, channel, airdate, expiration, episode, setreminder FROM lagunabeach where expiration >= now() order by airdate, 3 ASC LIMIT 0, 100;"); //You can also add reuslts to paginate here mysql_data_seek($queryresult,0) ; while($row = mysql_fetch_array($result)) { $paginator->add(new paginationData($row['programme'], $row['channel'], $row['airdate'], $row['expiration'], $row['episode'], $row['setreminder'])); } ?> <?php //Show the paginated results $paginator->paginate (); ?><? include("pca-footer1.php"); ?> <?php //Show the navigation $paginator->navigation(); ?> Despite me having two records for the programmes airing today, it only shows records from the second one onwards - the programme that airs at 8:35pm UK time GMT does not show, but the later 11:25pm UK time GMT one does show. How should I fix this? Above is my code if that is of any use! Thanks

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• Do you use an exception class in your Perl programs? Why or why not?

  - by daotoad

  I've got a bunch of questions about how people use exceptions in Perl. I've included some background notes on exceptions, skip this if you want, but please take a moment to read the questions and respond to them. Thanks. Background on Perl Exceptions Perl has a very basic built-in exception system that provides a spring-board for more sophisticated usage. For example die "I ate a bug.\n"; throws an exception with a string assigned to $@. You can also throw an object, instead of a string: die BadBug->new('I ate a bug.'); You can even install a signal handler to catch the SIGDIE psuedo-signal. Here's a handler that rethrows exceptions as objects if they aren't already. $SIG{__DIE__} = sub { my $e = shift; $e = ExceptionObject->new( $e ) unless blessed $e; die $e; } This pattern is used in a number of CPAN modules. but perlvar says: Due to an implementation glitch, the $SIG{DIE} hook is called even inside an eval(). Do not use this to rewrite a pending exception in $@ , or as a bizarre substitute for overriding CORE::GLOBAL::die() . This strange action at a distance may be fixed in a future release so that $SIG{DIE} is only called if your program is about to exit, as was the original intent. Any other use is deprecated. So now I wonder if objectifying exceptions in sigdie is evil. The Questions Do you use exception objects? If so, which one and why? If not, why not? If you don't use exception objects, what would entice you to use them? If you do use exception objects, what do you hate about them, and what could be better? Is objectifying exceptions in the DIE handler a bad idea? Where should I objectify my exceptions? In my eval{} wrapper? In a sigdie handler? Are there any papers, articles or other resources on exceptions in general and in Perl that you find useful or enlightening.

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• What is the best practice to segment c#.net projects based on a single base project

  - by Anthony

  Honestly, I can't word my question any better without describing it. I have a base project (with all its glory, dlls, resources etc) which is a CMS. I need to use this project as a base for othe custom bake projects. This base project is to be maintained and updated among all custom bake projects. I use subversion (Collabnet and Tortise SVN) I have two questions: 1 - Can I use subversion to share the base project among other projects What I mean here is can I "Checkout" the base project into another "Checked Out" project and have both update and commit seperatley. So, to paint a picture, let's say I am working on a custom project and I modify the core/base prject in some way (which I know will suit the others) can I then commit those changes and upon doing so when I update the base project in the other "Checked out" resources will it pull the changes? In short, I would like not to have to manually deploy updated core files whenever I make changes into each seperate project. 2 - If I create a custom file (let's say an webcontrol or aspx page etc) can I have it compile seperatley from the base project Another tricky one to explain. When I publish my web application it creates DLLs based on the namespaces of projects attached to it. So I may have a number of DLLs including the "Website's" namespace DLL, which could simply be website. I want to be able to make a seperate, custom, control which does not compile into those DLLs as the custom files should not rely on those DLLS to run. Is it as simple to set a seperate namespace for those files like CustomFiles.ProjectName for example? Think of the whole idea as adding modules to the .NET project, I don't want the module's code in any of the core DLLs but I do need for module to be able to access the core dlls. (There is no need for the core project to access the module code as it should be one way only in theory, though I reckon it woould not be possible anyway without using JSON/SOAP or something like that, maybe I am wrong.) I want to create a pluggable environment much like that of Joomla/Wordpress as since PHP generally doesn't have to be compiled first I see this is the reason why all this is possible/easy. The idea is to allow pluggable themes, modules etc etc. (I haven't tried simply adding .NET themes after compile/publish but I am assuming this is possible anyway? OR does the compiler need to reference items in the files?)

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• plane bombing problems- help

  - by peiska

  I'm training code problems, and on this one I am having problems to solve it, can you give me some tips how to solve it please. The problem is something like this: Your task is to find the sequence of points on the map that the bomber is expected to travel such that it hits all vital links. A link from A to B is vital when its absence isolates completely A from B. In other words, the only way to go from A to B (or vice versa) is via that link. Notice that if we destroy for example link (d,e), it becomes impossible to go from d to e,m,l or n in any way. A vital link can be hit at any point that lies in its segment (e.g. a hit close to d is as valid as a hit close to e). Of course, only one hit is enough to neutralize a vital link. Moreover, each bomb affects an exact circle of radius R, i.e., every segment that intersects that circle is considered hit. Due to enemy counter-attack, the plane may have to retreat at any moment, so the plane should follow, at each moment, to the closest vital link possible, even if in the end the total distance grows larger. Given all coordinates (the initial position of the plane and the nodes in the map) and the range R, you have to determine the sequence of positions in which the plane has to drop bombs. This sequence should start (takeoff) and finish (landing) at the initial position. Except for the start and finish, all the other positions have to fall exactly in a segment of the map (i.e. it should correspond to a point in a non-hit vital link segment). The coordinate system used will be UTM (Universal Transverse Mercator) northing and easting, which basically corresponds to a Euclidian perspective of the world (X=Easting; Y=Northing). Input Each input file will start with three floating point numbers indicating the X0 and Y0 coordinates of the airport and the range R. The second line contains an integer, N, indicating the number of nodes in the road network graph. Then, the next N (<10000) lines will each contain a pair of floating point numbers indicating the Xi and Yi coordinates (1 No two links will ever cross with each other. Output The program will print the sequence of coordinates (pairs of floating point numbers with exactly one decimal place), each one at a line, in the order that the plane should visit (starting and ending in the airport). Sample input 1 102.3 553.9 0.2 14 342.2 832.5 596.2 638.5 479.7 991.3 720.4 874.8 744.3 1284.1 1294.6 924.2 1467.5 659.6 1802.6 659.6 1686.2 860.7 1548.6 1111.2 1834.4 1054.8 564.4 1442.8 850.1 1460.5 1294.6 1485.1 17 1 2 1 3 2 4 3 4 4 5 4 6 6 7 7 8 8 9 8 10 9 10 10 11 6 11 5 12 5 13 12 13 13 14 Sample output 1 102.3 553.9 720.4 874.8 850.1 1460.5 102.3 553.9

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• In R, how do you get the best fitting equation to a set of data?

  - by Matherion

  I'm not sure wether R can do this (I assume it can, but maybe that's just because I tend to assume that R can do anything :-)). What I need is to find the best fitting equation to describe a dataset. For example, if you have these points: df = data.frame(x = c(1, 5, 10, 25, 50, 100), y = c(100, 75, 50, 40, 30, 25)) How do you get the best fitting equation? I know that you can get the best fitting curve with: plot(loess(df$y ~ df$x)) But as I understood you can't extract the equation, see Loess Fit and Resulting Equation. When I try to build it myself (note, I'm not a mathematician, so this is probably not the ideal approach :-)), I end up with smth like: y.predicted = 12.71 + ( 95 / (( (1 + df$x) ^ .5 ) / 1.3)) Which kind of seems to approximate it - but I can't help to think that smth more elegant probably exists :-) I have the feeling that fitting a linear or polynomial model also wouldn't work, because the formula seems different from what those models generally use (i.e. this one seems to need divisions, powers, etc). For example, the approach in Fitting polynomial model to data in R gives pretty bad approximations. I remember from a long time ago that there exist languages (Matlab may be one of them?) that do this kind of stuff. Can R do this as well, or am I just at the wrong place? (Background info: basically, what we need to do is find an equation for determining numbers in the second column based on the numbers in the first column; but we decide the numbers ourselves. We have an idea of how we want the curve to look like, but we can adjust these numbers to an equation if we get a better fit. It's about the pricing for a product (a cheaper alternative to current expensive software for qualitative data analysis); the more 'project credits' you buy, the cheaper it should become. Rather than forcing people to buy a given number (i.e. 5 or 10 or 25), it would be nicer to have a formula so people can buy exactly what they need - but of course this requires a formula. We have an idea for some prices we think are ok, but now we need to translate this into an equation.

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• Thoughts on streamlining multiple .Net apps

  - by John Virgolino

  We have a series of ASP.Net applications that have been written over the course of 8 years. Mostly in the first 3-4 years. They have been running quite well with little maintenance, but new functionality is being requested and we are running into IDE and platform issues. The apps were written in .Net 1.x and 2.x and run in separate spaces but are presented as a single suite of applications which use a common navigation toolbar (implemented as a user control). Every time we want to add something to a menu in the nav we have to modify it in all the apps which is a pain. Also, the various versions of Crystal reports and that we used tables to organize the visual elements and we end up with a mess, especially with all the multi-platform .Net versions running. We need to streamline the suite of apps and make it easier to add on new apps without a hassle. We also need to bring all these apps under one .Net platform and IDE. In addition, there is a WordPress blog styled to match the style of the application suite "integrated" into the UI and a link to a MediaWiki Wiki application as well. My current thinking is to use an open source content management system (CMS) like Joomla (PHP based unfortunately, but it works well) as the user interface framework for style templating and menu management. Joomla's article management would allow us to migrate the Wiki content into articles which could be published without interfering with the .Net apps. Then essentially use an IFrame within an "article" to "host" the .Net application, then... Upgrade the .Net apps to VS2010, strip out all the common header/footer controls and migrate the styles to use the style sheets used in the CMS. As I write this, I certainly realize this is a lot of work and there are optimization issues which this may cause as well as using IFrames seems a bit like cheating and I've read about issues with IFrames. I know that we could use .Net application styling, but it seems like a lot more work (not sure really). Also, the use of a CMS to handle the blog and wiki also seems appealing, unless there is a .Net CMS out there that can handle all of these requirements. Given this information, I am looking to know if I am totally going in the wrong direction? We tried to use open source and integrate it over time, but not this has become hard to maintain. Am I not aware of some technology out there that will meet our requirements? Did we do this right and should we just focus on getting the .Net streamlined? I understand that no matter what we do, it's going to be a lot of work. The communities considerable experience would be helpful. Thanks!! PS - A complete rewrite is not an option.

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