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• Classification: Dealing with Abstain/Rejected Class

  - by abner.ayala

  I am asking for your input and/help on a classification problem. If anyone have any references that I can read to help me solve my problem even better. I have a classification problem of four discrete and very well separated classes. However my input is continuous and has a high frequency (50Hz), since its a real-time problem. The circles represent the clusters of the classes, the blue line the decision boundary and Class 5 equals the (neutral/resting do nothing class). This class is the rejected class. However the problem is that when I move from one class to the other I activate a lot of false positives in the transition movements, since the movement is clearly non-linear. For example, every time I move from class 5 (neutral class) to 1 I first see a lot of 3's before getting to the 1 class. Ideally, I will want my decision boundary to look like the one in the picture below where the rejected class is Class =5. Has a higher decision boundary than the others classes to avoid misclassification during transition. I am currently implementing my algorithm in Matlab using naive bayes, kNN, and SVMs optimized algorithms using Matlab. Question: What is the best/common way to handle abstain/rejected classes classes? Should I use (fuzzy logic, loss function, should I include resting cluster in the training)?

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• Problem with DSL and Business Rules creation in Drools

  - by jillika iyer

  Hi, I am using Eclipse with the Drools plugin to create rules. I want to create business rules and main aim is to try and provide the user a set of options which he can use to create rules. For eg:If an Apple can have only 3 colors: I want to provide an option like a drop down so that the user can know before hand which are the options he can use in his rules. Is it possible? I am creating a dsl but unable to still provide the above functionality for a business rule. I am having an error implementing a basic dsl also. The code to add the dsl is as follows in my RuleRunner class() InputStream ruleSource = RuleRunner.class.getClassLoader().getResourceAsStream("/Rule1.dslr"); InputStream dslSource = RuleRunner.class.getClassLoader().getResourceAsStream("/sample-dsl.dsl"); //Load the rules , using DSL addRulesToThisPackage.addPackageFromDrl( new InputStreamReader(ruleSource),new InputStreamReader(dslSource)); I have both the sample-dsl .dsl and Rule1.dslr in my working directory. Error encountered at adding the dsl to the package (last line) Error stack: Exception in thread "main" java.lang.NullPointerException at java.io.Reader.<init>(Unknown Source) at java.io.InputStreamReader.<init>(Unknown Source) at com.org.RuleRunner.loadRuleFile(RuleRunner.java:96) at com.org.RuleRunner.loadRules(RuleRunner.java:48) at com.org.RuleRunner.runStatelessRules(RuleRunner.java:109) at com.org.RulesTest.main(RulesTest.java:41) my dsl file has basic mapping as per the online documentations. The dsl rule I created is: expander sample-dsl.dsl rule "A status changes B status" when There is an A - has an address There is a B - has name then - print updated A and Aaddress End I have created DSL in eclipse. Is the code I added for it to be loaded to my package correct?? Or am I missing something???? It seems like my program is unable to find the dsl? Please help. Can you point me towards the right direction to create a user friendly business rule ?? Thanks. J

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• Compilation Error: "The modifier 'public' is not valid for this item" while creating public method o

  - by Lalit

  I am getting this error while creating public method on a class for explicitly implementing the interface. I have the workaround: by removing the explicit implementation of PrintName Method, But surprised why i am getting this error. Can anyone explain the error. Code for Library: using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace Test.Lib1 { public class Customer : i1 { public string i1.PrintName() //Error Here... { return this.GetType().Name + " called from interface i1"; } } public interface i1 { string PrintName(); } interface i2 { string PrintName(); } } Code for Console Test Application: using System; using System.Collections.Generic; using System.Linq; using System.Text; using Test.Lib1; namespace ca1.Test { class Program { static void Main(string[] args) { Customer customer = new Customer(); Console.WriteLine(customer.PrintName()); //i1 i1o = new Customer(); //Console.WriteLine(i1o.printname()); //i2 i2o = new Customer(); //Console.WriteLine(i2o.printname()); } } }

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• Auditing in Entity Framework.

  - by Gabriel Susai

  After going through Entity Framework I have a couple of questions on implementing auditing in Entity Framework. I want to store each column values that is created or updated to a different audit table. Rightnow I am calling SaveChanges(false) to save the records in the DB(still the changes in context is not reset). Then get the added | modified records and loop through the GetObjectStateEntries. But don't know how to get the values of the columns where their values are filled by stored proc. ie, createdate, modifieddate etc. Below is the sample code I am working on it. //Get the changed entires( ie, records) IEnumerable<ObjectStateEntry> changes = context.ObjectStateManager.GetObjectStateEntries(EntityState.Modified); //Iterate each ObjectStateEntry( for each record in the update/modified collection) foreach (ObjectStateEntry entry in changes) { //Iterate the columns in each record and get thier old and new value respectively foreach (var columnName in entry.GetModifiedProperties()) { string oldValue = entry.OriginalValues[columnName].ToString(); string newValue = entry.CurrentValues[columnName].ToString(); //Do Some Auditing by sending entityname, columnname, oldvalue, newvalue } } changes = context.ObjectStateManager.GetObjectStateEntries(EntityState.Added); foreach (ObjectStateEntry entry in changes) { if (entry.IsRelationship) continue; var columnNames = (from p in entry.EntitySet.ElementType.Members select p.Name).ToList(); foreach (var columnName in columnNames) { string newValue = entry.CurrentValues[columnName].ToString(); //Do Some Auditing by sending entityname, columnname, value } }

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• Thread safe lazy contruction of a singleton in C++

  - by pauldoo

  Is there a way to implement a singleton object in C++ that is: Lazily constructed in a thread safe manner (two threads might simultaneously be the first user of the singleton - it should still only be constructed once). Doesn't rely on static variables being constructed beforehand (so the singleton object is itself safe to use during the construction of static variables). (I don't know my C++ well enough, but is it the case that integral and constant static variables are initialized before any code is executed (ie, even before static constructors are executed - their values may already be "initialized" in the program image)? If so - perhaps this can be exploited to implement a singleton mutex - which can in turn be used to guard the creation of the real singleton..) Excellent, it seems that I have a couple of good answers now (shame I can't mark 2 or 3 as being the answer). There appears to be two broad solutions: Use static initialisation (as opposed to dynamic initialisation) of a POD static varible, and implementing my own mutex with that using the builtin atomic instructions. This was the type of solution I was hinting at in my question, and I believe I knew already. Use some other library function like pthread_once or boost::call_once. These I certainly didn't know about - and am very grateful for the answers posted.

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• PayPal integration woes: PDT hangs on return to site

  - by Tom

  Hi, I'm implementing PayPal IPN & PDT. After some headache & time at the sandbox, IPN is working well and PDT returns the correct $_GET data. The implementation is as follows: Pass user ID in form to PayPal User buys product and triggers IPN which updates database for given user ID PDT returns transaction ID when user returns to site The return page says "please wait" and repeat-Ajax-checks for the transaction status User is redirected to success/failure page Everything works well, EXCEPT that when using the PayPal ready PHP code for PDT to do a return POST, the page hangs. PayPal waits for a response and the user never gets back to my site. I'm not getting a fail status, just nothing. The funny thing is that once the unknown error occurs, my test domain becomes unresponsive for a short period. The code (PHP): https://www.paypal.com/us/cgi-bin/webscr?cmd=p/xcl/rec/pdt-code-outside If I comment out the POST back, it all works fine. I'm able to pin down the problem to once the code enters the while{} loop. Unfortunately, I'm not experienced enough to write a replacement from scratch for the PayPal code, so would really appreciate any ideas on what might be wrong. The POST back goes to ssl://www.sandbox.paypal.com, and I'm using button code and an authorisation token that have all been created via a sandbox test account. Thanks in advance.

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• How do I write test code to exercise a C# generic Pair<TKey, TValue> ?

  - by Scott Davies

  Hi, I am reading through Jon Skeet's "C# in Depth", first edition (which is a great book). I'm in section 3.3.3, page 84, "Implementing Generics". Generics always confuse me, so I wrote some code to exercise the sample. The code provided is: using System; using System.Collections.Generic; public sealed class Pair<TFirst, TSecond> : IEquatable<Pair<TFirst, TSecond>> { private readonly TFirst first; private readonly TSecond second; public Pair(TFirst first, TSecond second) { this.first = first; this.second = second; } ...property getters... public bool Equals(Pair<TFirst, TSecond> other) { if (other == null) { return false; } return EqualityComparer<TFirst>.Default.Equals(this.First, other.First) && EqualityComparer<TSecond>.Default.Equals(this.Second, other.Second); } My code is: class MyClass { public static void Main (string[] args) { // Create new pair. Pair thePair = new Pair(new String("1"), new String("1")); // Compare a new pair to previous pair by generating a second pair. if (thePair.Equals(new Pair(new string("1"), new string("1")))) System.Console.WriteLine("Equal"); else System.Console.WriteLine("Not equal"); } } The compiler complains: "Using the generic type 'ManningListing36.Paie' requires 2 type argument(s) CS0305" What am I doing wrong ? Thanks, Scott

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• why won't Eclipse use the compiler I specify for my project?

  - by codeman73

  I'm using Eclipse 3.3. In my project, I've set the compiler compliance level to 5.0 In the build path for the project. I've added the Java 1.5 JDK in the Installed JREs section and am referencing that System Library in my project build path. However, I'm getting compile errors for a class that implements PreparedStatement for not implementing abstract methods that only exist in Java 1.6 PreparedStatement. Specifically, the methods setAsciiStream(int, InputStream, long) and setAsciiStream(int, InputStream) Strangely enough, it worked when we were compiling it against Java 1.4, which it was originally written for. We added the JREs for Java 1.4 and referenced that system library in the project, and set the project's compiler level to 1.4, and it works fine. But when I do the same changes to try to point to Java 5.0, it instead uses Java 6. Any ideas why? I wrote a similar question earlier, here: http://stackoverflow.com/questions/2540548/how-do-i-get-eclipse-to-use-a-different-compiler-version-for-java I know how you're supposed to choose a different compiler but it seems Eclipse isn't taking it. It seems to be defaulting to Java 6, even though I have deleted all Java 6 JDKs and JREs that I could find. I've also updated the -vm option in my eclipse.ini to point to the Java5 JDK.

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• PHP Post Count in Forum

  - by Chris

  I'm currently desiging a forum application, I considered using a premade but decided against it as it's useful for me to learn some of the techniques. So I've written a fairly full featured forum... great. One of the problems I want to solve is to include user data for each post, at the minute the post table includes the poster ID (obviously) and I added the poster's username at a later date so I didn't have to query the User DB for X number of posts in a thread. However, it's become apparent I now want to do this, usernames don't need to update retrospectively, however avatars, sigs, and especially post counts need to update actively, so data in some form needs keeping up to date somewhere... What would be a good way of implementing this? I obviously don't want to include any more user data on the Posts DB table than necessary, but I'm struggling to find an easy way to do this short of querying the DB for each post in a thread, which is potentially going to create a lot of traffic. How have other people solved this, I've been examining the code on some other open source apps but I can't find what I'm looking for. Is it possible to select multiple records in one query? In which case I could build an array dynamically on each page request (eg 'SQL blah blah' then a for each loop to insert the ID's). Could I join the tables each time? Do I submit a query for each post? Hmm.

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• WPF and events from dynamically created controls

  - by OKB

  Hi, I need some help to implement a common behavior in some controls. In my WPF application, I have a main form that contains a panel and a button: Ok The button will run a Save method when clicked.The Save method reads some data from the form and saves the data to a database. The panel is populated with dynamically created controls (such as textbox, dropdownlists, etc). The main form instantiates a MainViewModel class. This MainViewModel class instantiates a class called UIFactory. So we have 3 levels here. In the UIFactory class the controls is being created. The Panel from the main form is sent as a parameter to a method in the MainModelView class called GenerateUI. This GenerateUI method in the MainViewModel class calls a GenerateControls method on the UIFactory class that takes the same panel as a parameter. The GenerateControls method in the UIFactory class then adds dynamically created controls on the panel. What I want to achieve is that whenever the user hits ENTER when he is typing in one of those dynamically created controls e.g a textbox, I want that behavior to be the same as clicking on the button in my main form. But how do I do that? I thought of implementing Routed events on my controls, but I can't figure out how to do it. Could you please advise me on how to achieve my goal? Best Regards, OKB

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• How do I test database-related code with NUnit?

  - by Michael Haren

  I want to write unit tests with NUnit that hit the database. I'd like to have the database in a consistent state for each test. I thought transactions would allow me to "undo" each test so I searched around and found several articles from 2004-05 on the topic: http://weblogs.asp.net/rosherove/archive/2004/07/12/180189.aspx http://weblogs.asp.net/rosherove/archive/2004/10/05/238201.aspx http://davidhayden.com/blog/dave/archive/2004/07/12/365.aspx http://haacked.com/archive/2005/12/28/11377.aspx These seem to resolve around implementing a custom attribute for NUnit which builds in the ability to rollback DB operations after each test executes. That's great but... Does this functionality exists somewhere in NUnit natively? Has this technique been improved upon in the last 4 years? Is this still the best way to test database-related code? Edit: it's not that I want to test my DAL specifically, it's more that I want to test pieces of my code that interact with the database. For these tests to be "no-touch" and repeatable, it'd be awesome if I could reset the database after each one. Further, I want to ease this into an existing project that has no testing place at the moment. For that reason, I can't practically script up a database and data from scratch for each test.

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• ListView Final Column Autosize creates scrollbar

  - by Courtney de Lautour

  Hi There, I am implementing a custom control which derives from ListView. I would like for the final column to fill the remaining space (Quite a common task), I have gone about this via overriding the OnResize method: protected override void OnResize(EventArgs e) { base.OnResize(e); if (Columns.Count == 0) return; Columns[Columns.Count - 1].Width = -2; // -2 = Fill remaining space } or via another method: protected override void OnResize(EventArgs e) { base.OnResize(e); if (!_autoFillLastColumn) return; if (Columns.Count == 0) return; int TotalWidth = 0; int i = 0; for (; i < Columns.Count - 1; i++) { TotalWidth += Columns[i].Width; } Columns[i].Width = this.DisplayRectangle.Width - TotalWidth; } Edit: This works fine until I dock the ListView into a parent container and resize via that control. Every second time the control size shrinks (IE, drag the the border one pixel), I get a scroll bar on the bottom which can't move at all (not even one pixel). The result of which is when I drag the size of the parent I am left with a flickering scroll bar in the ListView, and a 50% chance it will be there when the dragging stops.

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• Programmatically disable WiredHeadset

  - by tyrone-tudehope

  Hi, I have an HTC Hero with a major issue. It thinks that the headset/headphones are plugged in. I sent it to HTC and they said there is water damage so no fix. I have tried toggleheadset, toggleheadset2. I've rooted my device and installed the Android 2.1 ROM. Now I found out that AudioManager.setRouting and .setWiredHeadsetOn(bool) have been deprecated and subsequently removed. I read a post somewhere about how you can create a wrapper for the AudioSystem class as the setRouting is still available there. I as of yet have not been able to figure out how to go about doing this as the AudioSystem class is hidden in the SDK and the code makes use of native functions. Does anybody know of a way to go about creating and implementing a wrapper for AudioSystem or of another way to disable the headset? P.S. I've cleaned out the headset port so there is no dust or anything sending false signals to the mainboard. Any help will be greatly appreciated. Thanks, Tyrone

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• Linked List Sorting with Strings In C

  - by user308583

  I have a struct, with a Name and a single Node called nextName It's a Singly Linked list, and my task is to create the list, based on alphabetical order of the strings. So iff i enter Joe Zolt and Arthur i should get my list structured as Joe Than Joe Zolt Than Arthur Joe Zolt I'm having trouble implementing the correct Algorithm, which would put the pointers in the right order. This is What I have as of Now. Temp would be the name the user just entered and is trying to put into the list, namebox is just a copy of my root, being the whole list if(temp != NULL) { struct node* namebox = root; while (namebox!=NULL && (strcmp((namebox)->name,temp->name) <= 0)) { namebox = namebox->nextName; printf("here"); } temp->nextName = namebox; namebox = temp; root = namebox; This Works right now, if i enter names like CCC BBB than AAA I Get Back AAA BBB CCC when i print But if i put AAA BBB CCC , When i print i only get CCC, it cuts the previous off.

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• Problem with TTWebController… alternative view controller template for UIWebView?

  - by prendio2

  I have a UIWebView with content populated from a Last.fm API call. This content contains links, many of which are handled by parsing info from the URL in: - (BOOL)webView:(UIWebView *)aWbView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType; …and passing that info on to appropraite view controllers. When I cannot handle a URL I would like to push a new view controller on the stack and load the webpage into a UIWebView there. The TTWebController in Three20 looks very promising since it has also implemented a navigation toolbar, loading indicators etc. Somewhat naively perhaps I thought I would be able to use this controller to display web content in my app, without implementing Three20 throughout the app. I followed the instructions on github to add Three20 to my project and added the following code to deal with URLs in shouldStartLoadWithRequest: TTWebController* browser = [[TTWebController alloc]init]; [browser openURL:@"http://three20.info"]; //initially test with this URL [self.navigationController pushViewController:navigator animated:YES]; This crashes my app however with the following notice: *** -[TTNavigator setParentViewController:]: unrecognized selector sent to instance 0x3d5db70 What else do I need to do to implement the TTWebController in my app? Or do you know of an alternative view controller template that I can use instead of the Three20 implementation?

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• How to make UISlider output nice rounded numbers exponentially?

  - by RickiG

  Hi I am implementing a UISlider a user can manipulate to set a distance. I have never used the CocoaTouch UISlider, but have used other frameworks sliders, usually there is a variable for setting the "step" and other "helper" properties. The documentation for the UISlider deals only with a max and min value, and the output is always a 6 decimal float with a linear relation to the position of the "slider nob". I guess I will have to implement the desired functionality step by step. To the user, the min/max values range from 10 m to 999 Km, I am trying to implement this in an exponential way, that will feel natural to the user. I.e. the user experiences a feeling of control over the values, big or small. Also that the "output" has reasonable values. Values like 10m 200m 2.5km 150 km etc. instead of 1.2342356 m or 108.93837756 km. I would like for the step size to increase by 10m for the first 200m, then maybe by 50m up to 500m, then when passing the 1000 m value, it starts to deal with Kilometers, so then it is step size = 1 km up until 50 km, then maybe 25 km steps etc. Any way I go about this I end up doing a lot of rounding and a lot of calculations wrapped in a forrest of if statements and NSString/Number conversions, each time the user moves the slider just a little. I was hoping someone could lend me a bit of inspiration/math help or make me aware of a more lean approach to solving this problem. My last idea is to populate and array with a 100 string values, then have the slider int value correspond to a string, this is not very flexible, but doable. Thank you in advance for any help given:)

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• Beyond core java

  - by Paul

  Coming to the end of the first year of my CS degree, we've done some Java but just the core stuff; manipulating strings and arrays, inheritance, implementing logic etc. I visit this website daily and I see so much stuff that is beyond me; using frameworks; managing databases etc. It makes me feel like I've just learned the syntax of Java, and there is so much more to do with it. My question is though, how do I get there? I don't think I'm advanced enough to join an open source project, which seems to be suggested often (though I'd love to) and I've looked at other similar questions on here (like this one) but even then I don't think that'd work for me.. firstly, could somebody try give me some commonly used frameworks etc and how and what they are used for? Where would be a good place to start? How did you get started in using the things you do? Or perhaps you think I'm going down the wrong route. Should I learn another language, and just wait until the moment occurs where it's clear what I should be doing? I'm only in the first year of my degree, so far we've lightly covered Haskell and Java, and I've done a little HTML and CSS in my free time. I know that next year we cover python, so perhaps I should just wait till then and see if I prefer that? I feel like I also risk learning something in depth and then never using it... I suppose I'm also asking for personal experiences; was there a point where you felt you'd exceeded the basic grasp of a language (does not necessarily have to be Java related) and reach a more "advanced" level? I guess I'll put subjective tag on this, but really I just want to know how to get beyond the basic understanding of a language.

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• Export database data to csv from view by date range asp.net mvc3

  - by Benjamin Randal

  I am trying to find a way to export data from my database and save it as a .csv file. Ideally the user will be able to select a date range on a view, which will display the data to be exported, then the user can click an "export to CSV" link. I've done quite a bit of searching and but have not found much specific enough to help me step through the process. Any help would be great. I would like to export data from this database model... { public class InspectionInfo { [Key] public int InspectionId { get; set; } [DisplayName("Date Submitted")] [DataType(DataType.Date)] // [Required] public DateTime Submitted { get; set; } [DataType(DataType.MultilineText)] [MaxLength(1000)] // [Required] public string Comments { get; set; } // [Required] public Contact Contact { get; set; } [ForeignKey("Contact")] public Int32 ContactId { get; set; } [MaxLength(100)] public String OtherContact { get; set; } I have a service for search also, just having difficulty implementing public SearchResults SearchInspections(SearchRequest request) { using (var db = new InspectionEntities()) { var results = db.InspectionInfos .Where( i=> ( (null == request.StartDate || i.Submitted >= request.StartDate.Value) && (null == request.EndDate || i.Submitted <= request.EndDate.Value) ) ) .OrderBy(i=>i.Submitted) .Skip(request.PageSize*request.PageIndex).Take(request.PageSize); return new SearchResults{ TotalResults=results.Count(), PageIndex=request.PageIndex, Inspections=results.ToList(), SearchRequest=request }; } }

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• Pros/cons of reading connection string from physical file vs Application object (ASP.NET)?

  - by HaterTot

  my ASP.NET application reads an xml file to determine which environment it's currently in (e.g. local, development, production). It checks this file every single time it opens a connection to the database, in order to know which connection string to grab from the Application Settings. I'm entering a phase of development where efficiency is becoming a concern. I don't think it's a good idea to have to read a file on a physical disk ever single time I wish to access the database (very often). I was considering storing the connection string in Application["ConnectionString"]. So the code would be public static string GetConnectionString { if (Application["ConnectionString"] == null) { XmlDocument doc = new XmlDocument(); doc.Load(HttpContext.Current.Request.PhysicalApplicationPath + "bin/ServerEnvironment.xml"); XmlElement xe = (XmlElement) xnl[0]; switch (xe.InnerText.ToString().ToLower()) { case "local": connString = Settings.Default.ConnectionStringLocal; break; case "development": connString = Settings.Default.ConnectionStringDevelopment; break; case "production": connString = Settings.Default.ConnectionStringProduction; break; default: throw new Exception("no connection string defined"); } Application["ConnectionString"] = connString; } return Application["ConnectionString"].ToString(); } I didn't design the application so I figure there must have been a reason for reading the xml file every time (to change settings while the application runs?) I have very little concept of the inner workings here. What are the pros and cons? Do you think I'd see a small performance gain by implementing the function above? THANKS

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• Biztalk vs API for databroker layer

  - by jdt199

  My company is about to undergo a large project in which our client wants a large customer portal with a cms, crm implementing. This will require interaction with data from multiple sources across our customers business, these sources include XML office backend systems, sql datbases, webservices etc. Our proposed solution would be to write an API in c# to provide a common interface with all these systems. This would be scalable for future and concurrent projects within the company. Our client expressed an interest in using Biztalk rather than a custom API for this integration, as they feel it is an enterprise solution that any of their suppliers could pick up and use, and it will be better supported. We feel that the configuration work using Biztalk would be rather heavy for all their custom business rules which are required and an interface for the new application to get data to and from Biztalk would still need to be written. Are we right to prefer a custom API solution above Biztalk? Would Biztalk be suitable as a databroker layer to provide an interface for the new Customer portal we are writing. We have not experience with using Biztalk before so any input would be appreciated.

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• Do fluent interfaces significantly impact runtime performance of a .NET application?

  - by stakx

  I'm currently occupying myself with implementing a fluent interface for an existing technology, which would allow code similar to the following snippet: using (var directory = Open.Directory(@"path\to\some\directory")) { using (var file = Open.File("foobar.html").In(directory)) { // ... } } In order to implement such constructs, classes are needed that accumulate arguments and pass them on to other objects. For example, to implement the Open.File(...).In(...) construct, you would need two classes: // handles 'Open.XXX': public static class OpenPhrase { // handles 'Open.File(XXX)': public static OpenFilePhrase File(string filename) { return new OpenFilePhrase(filename); } // handles 'Open.Directory(XXX)': public static DirectoryObject Directory(string path) { // ... } } // handles 'Open.File(XXX).XXX': public class OpenFilePhrase { internal OpenFilePhrase(string filename) { _filename = filename } // handles 'Open.File(XXX).In(XXX): public FileObject In(DirectoryObject directory) { // ... } private readonly string _filename; } That is, the more constituent parts statements such as the initial examples have, the more objects need to be created for passing on arguments to subsequent objects in the chain until the actual statement can finally execute. Question: I am interested in some opinions: Does a fluent interface which is implemented using the above technique significantly impact the runtime performance of an application that uses it? With runtime performance, I refer to both speed and memory usage aspects. Bear in mind that a potentially large number of temporary, argument-saving objects would have to be created for only very brief timespans, which I assume may put a certain pressure on the garbage collector. If you think there is significant performance impact, do you know of a better way to implement fluent interfaces?

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• Why is it not good to use $_SESSION in Restful Implementations?

  - by keisimone

  Original Question: i read that for RESTful websites. it is not good to use $_SESSION. Why is it not good? how then do i properly authenticate users without looking up database all the time to check for the user's roles? I read that it is not good to use $_SESSION. http://www.recessframework.org/page/towards-restful-php-5-basic-tips I am creating a WEBSITE, not web service in PHP. and i am trying to make it more RESTful. at least in spirit. right now i am rewriting all the action to use Form tags POST and add in a hidden value called _method which would be "delete" for deleting action and "put" for updating action. however, i am not sure why it is recommended NOT to use $_SESSION. i would like to know why and what can i do to improve. To allow easy authorization checking, what i did was to after logging in the user, the username is stored in the $_SESSION. Everytime the user navigates to a page, the page would check if the username is stored inside $_SESSION and then based on the $_SESSION retrieves all the info including privileges from the database and then evaluates the authorization to access the page based on the info retrieved. Is the way I am implementing bad? not RESTful? how do i improve performance and security? Thank you.

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• Partial Classes - are they bad design?

  - by dferraro

  Hello, I'm wondering why the 'partial class' concept even exists in .NET. I'm working on an application and we are reading a (actually very good) book relavant to the development platform we are implementing at work. In the book he provides a large code base /wrapper around the platform API and explains how he developed it as he teaches different topics about the platform development. Anyway, long story short - he uses partial classes, all over the place, as a way to fake multiple inheritence in C# (IMO). Why he didnt just split the classes up into multiple ones and use composition is beyond me. He will have 3 'partial class' files to make up his base class, each w/ 3-500 lines of code... And does this several times in his API. Do you find this justifiable? If it were me, I'd have followed the S.R.P. and created multiple classes to handle different required behaviors, then create a base class that has instances of these classes as members (e.g. composition). Why did MS even put partial class into the framework?? They removed the ability to expand/collapse all code at each scope level in C# (this was allowed in C++) because it was obviously just allowing bad habits - partial class is IMO the same thing. I guess my quetion is: Can you explain to me when there would be a legitimate reason to ever use a partial class? I do not mean this to be a rant / war thread. I'm honeslty looking to learn something here. Thanks

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• Fluent Nhibernate Mapping Single class on two database tables

  - by nabeelfarid

  Hi guys, I am having problems with Mapping. I have two tables in my database as follows: Employee and EmployeeManagers Employee EmployeeId int Name nvarchar EmployeeManagers EmployeeIdFk int ManagerIdFk int So the employee can have 0 or more Managers. A manager itself is also an Employee. I have the following class to represent the Employee and Managers public class Employee { public virtual int Id { get; set; } public virtual string Name { get; set; } public virtual IList<Employee> Managers { get; protected set; } public Employee() { Managers = new List<Employee>(); } } I don't have any class to represent Manager because I think there is no need for it, as Manager itself is an Employee. I am using autoMapping and I just can't figure out how to map this class to these two tables. I am implementing IAutoMappingOverride for overriding automappings for Employee but I am not sure what to do in it. public class NodeMap : IAutoMappingOverride { public void Override(AutoMapping<Node> mapping) { //mapping.HasMany(x => x.ValidParents).Cascade.All().Table("EmployeeManager"); //mapping.HasManyToMany(x => x.ValidParents).Cascade.All().Table("EmployeeManager"); } } I also want to make sure that an employee can not be assigned the same manager twice. This is something I can verify in my application but I would like to put constraint on the EmployeeManager table (e.g. a composite key) so a same manager can not be assigned to an employee more than once. Could anyone out there help me with this please? Awaiting Nabeel

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• Is there a version of the removeElement function in Go for the vector package like Java has in its V

  - by Brian T Hannan

  I am porting over some Java code into Google's Go language and I converting all code except I am stuck on just one part after an amazingly smooth port. My Go code looks like this and the section I am talking about is commented out: func main() { var puzzleHistory * vector.Vector; puzzleHistory = vector.New(0); var puzzle PegPuzzle; puzzle.InitPegPuzzle(3,2); puzzleHistory.Push(puzzle); var copyPuzzle PegPuzzle; var currentPuzzle PegPuzzle; currentPuzzle = puzzleHistory.At(0).(PegPuzzle); isDone := false; for !isDone { currentPuzzle = puzzleHistory.At(0).(PegPuzzle); currentPuzzle.findAllValidMoves(); for i := 0; i < currentPuzzle.validMoves.Len(); i++ { copyPuzzle.NewPegPuzzle(currentPuzzle.holes, currentPuzzle.movesAlreadyDone); copyPuzzle.doMove(currentPuzzle.validMoves.At(i).(Move)); // There is no function in Go's Vector that will remove an element like Java's Vector //puzzleHistory.removeElement(currentPuzzle); copyPuzzle.findAllValidMoves(); if copyPuzzle.validMoves.Len() != 0 { puzzleHistory.Push(copyPuzzle); } if copyPuzzle.isSolutionPuzzle() { fmt.Printf("Puzzle Solved"); copyPuzzle.show(); isDone = true; } } } } If there is no version available, which I believe there isn't ... does anyone know how I would go about implementing such a thing on my own?

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