Search Results

Search found 11639 results on 466 pages for 'numerical methods'.

Page 111/466 | < Previous Page | 107 108 109 110 111 112 113 114 115 116 117 118  | Next Page >

• The illusion of Competence

  - by tony_lombardo

  Working as a contractor opened my eyes to the developer food chain.  Even though I had similar experiences earlier in my career, the challenges seemed much more vivid this time through.  I thought I’d share a couple of experiences with you, and the lessons that can be taken from them. Lesson 1: Beware of the “funnel” guy.  The funnel guy is the one who wants you to funnel all thoughts, ideas and code changes through him.  He may say it’s because he wants to avoid conflicts in source control, but the real reason is likely that he wants to hide your contributions.  Here’s an example.  When I finally got access to the code on one of my projects, I was told by the developer that I had to funnel all of my changes through him.  There were 4 of us coding on the project, but only 2 of us working on the UI.  The other 2 were working on a separate application, but part of the overall project.  So I figured, I’ll check it into SVN, he reviews and accepts then merges in.  Not even close.  I didn’t even have checkin rights to SVN, I had to email my changes to the developer so he could check those changes in.  Lesson 2: If you point out flaws in code to someone supposedly ‘higher’ than you in the developer chain, they’re going to get defensive.  My first task on this project was to review the code, familiarize myself with it.  So of course, that’s what I did.  And in familiarizing myself with it, I saw so many bad practices and code smells that I immediately started coming up with solutions to fix it.  Of course, when I reviewed these changes with the developer (guy who originally wrote the code), he smiled and nodded and said, we can’t make those changes now, it’s too destabilizing.  I recommended we create a new branch and start working on refactoring, but branching was a new concept for this guy and he was worried we would somehow break SVN. How about some concrete examples? I started out by recommending we remove NUnit dependency and tests from the application project, and create a separate Unit testing project.  This was met with a little bit of resistance because - “How do I access the private methods?”  As it turned out there weren’t really any private methods that weren’t exposed by public methods, so I quickly calmed this fear. Win 1 Loss 0 Next, I recommended that all of the File IO access be wrapped in Using clauses, or at least properly wrapped in try catch finally.  This recommendation was accepted.. but never implemented. Win 2  Loss 1 Next recommendation was to refactor the command pattern implementation.  The command pattern was implemented, but it wasn’t really necessary for the application.  More over, the fact that we had 100 different command classes, each with it’s own specific command parameters class, made maintenance a huge hassle.  The same code repeated over and over and over.  This recommendation was declined, the code was too fragile and this change would destabilize it.  I couldn’t disagree, though it was the commands themselves in many cases that were fragile. Win 2 Loss 2 Next recommendation was to aid performance (and responsiveness) of the application by using asynchronous service calls.  This on was accepted. Win 2 Loss 3 If you’re paying any attention, you’re wondering why the async service calls was scored as a loss.. Let me explain.  The service call was made using the async pattern.  Followed by a thread.sleep  <facepalm>. Now it’s easy to be harsh on this kind of code, especially if you’re an experienced developer.  But I understood how most of this happened.  One junior guy, working as hard as he can to build his first real world application, with little or no guidance from anyone else.  He had his pattern book and theory of programming to help him, but no real world experience.  He didn’t know how difficult it would be to trace the crashes to the coding issues above, but he will one day.  The part that amazed me was the management position that “this guy should be a team lead, because he’s worked so hard”.  I’m all for rewarding hard work, but when you reward someone by promoting them past the point of their competence, you’re setting yourself and them up for failure.  And that’s lesson 3.  Just because you’ve got a hard worker, doesn’t mean he should be leading a development project.  If you’re a junior guy busting your ass, keep at it.  I encourage you to try new things, but most importantly to learn from your mistakes.  And correct your mistakes.  And if someone else looks at your code and shows you a laundry list of things that should be done differently, don’t take it personally – they’re really trying to help you.  And if you’re a senior guy, working with a junior guy, it’s your duty to point out the flaws in the code.  Even if it does make you the bad guy.  And while I’ve used “guy” above, I mean both men and women.  And in some cases mutant dinosaurs. 

  Read the article

• Subterranean IL: Constructor constraints

  - by Simon Cooper

  The constructor generic constraint is a slightly wierd one. The ECMA specification simply states that it: constrains [the type] to being a concrete reference type (i.e., not abstract) that has a public constructor taking no arguments (the default constructor), or to being a value type. There seems to be no reference within the spec to how you actually create an instance of a generic type with such a constraint. In non-generic methods, the normal way of creating an instance of a class is quite different to initializing an instance of a value type. For a reference type, you use newobj: newobj instance void IncrementableClass::.ctor() and for value types, you need to use initobj: .locals init ( valuetype IncrementableStruct s1 ) ldloca 0 initobj IncrementableStruct But, for a generic method, we need a consistent method that would work equally well for reference or value types. Activator.CreateInstance<T> To solve this problem the CLR designers could have chosen to create something similar to the constrained. prefix; if T is a value type, call initobj, and if it is a reference type, call newobj instance void !!0::.ctor(). However, this solution is much more heavyweight than constrained callvirt. The newobj call is encoded in the assembly using a simple reference to a row in a metadata table. This encoding is no longer valid for a call to !!0::.ctor(), as different constructor methods occupy different rows in the metadata tables. Furthermore, constructors aren't virtual, so we would have to somehow do a dynamic lookup to the correct method at runtime without using a MethodTable, something which is completely new to the CLR. Trying to do this in IL results in the following verification error: newobj instance void !!0::.ctor() [IL]: Error: Unable to resolve token. This is where Activator.CreateInstance<T> comes in. We can call this method to return us a new T, and make the whole issue Somebody Else's Problem. CreateInstance does all the dynamic method lookup for us, and returns us a new instance of the correct reference or value type (strangely enough, Activator.CreateInstance<T> does not itself have a .ctor constraint on its generic parameter): .method private static !!0 CreateInstance<.ctor T>() { call !!0 [mscorlib]System.Activator::CreateInstance<!!0>() ret } Going further: compiler enhancements Although this method works perfectly well for solving the problem, the C# compiler goes one step further. If you decompile the C# version of the CreateInstance method above: private static T CreateInstance() where T : new() { return new T(); } what you actually get is this (edited slightly for space & clarity): .method private static !!T CreateInstance<.ctor T>() { .locals init ( [0] !!T CS$0$0000, [1] !!T CS$0$0001 ) DetectValueType: ldloca.s 0 initobj !!T ldloc.0 box !!T brfalse.s CreateInstance CreateValueType: ldloca.s 1 initobj !!T ldloc.1 ret CreateInstance: call !!0 [mscorlib]System.Activator::CreateInstance<T>() ret } What on earth is going on here? Looking closer, it's actually quite a clever performance optimization around value types. So, lets dissect this code to see what it does. The CreateValueType and CreateInstance sections should be fairly self-explanatory; using initobj for value types, and Activator.CreateInstance for reference types. How does the DetectValueType section work? First, the stack transition for value types: ldloca.s 0 // &[!!T(uninitialized)] initobj !!T // ldloc.0 // !!T box !!T // O[!!T] brfalse.s // branch not taken When the brfalse.s is hit, the top stack entry is a non-null reference to a boxed !!T, so execution continues to to the CreateValueType section. What about when !!T is a reference type? Remember, the 'default' value of an object reference (type O) is zero, or null. ldloca.s 0 // &[!!T(null)] initobj !!T // ldloc.0 // null box !!T // null brfalse.s // branch taken Because box on a reference type is a no-op, the top of the stack at the brfalse.s is null, and so the branch to CreateInstance is taken. For reference types, Activator.CreateInstance is called which does the full dynamic lookup using reflection. For value types, a simple initobj is called, which is far faster, and also eliminates the unboxing that Activator.CreateInstance has to perform for value types. However, this is strictly a performance optimization; Activator.CreateInstance<T> works for value types as well as reference types. Next... That concludes the initial premise of the Subterranean IL series; to cover the details of generic methods and generic code in IL. I've got a few other ideas about where to go next; however, if anyone has any itching questions, suggestions, or things you've always wondered about IL, do let me know.

  Read the article

• Implementing synchronous MediaTypeFormatters in ASP.NET Web API

  - by cibrax

  One of main characteristics of MediaTypeFormatter’s in ASP.NET Web API is that they leverage the Task Parallel Library (TPL) for reading or writing an model into an stream. When you derive your class from the base class MediaTypeFormatter, you have to either implement the WriteToStreamAsync or ReadFromStreamAsync methods for writing or reading a model from a stream respectively. These two methods return a Task, which internally does all the serialization work, as it is illustrated bellow. public abstract class MediaTypeFormatter { public virtual Task WriteToStreamAsync(Type type, object value, Stream writeStream, HttpContent content, TransportContext transportContext); public virtual Task<object> ReadFromStreamAsync(Type type, Stream readStream, HttpContent content, IFormatterLogger formatterLogger); }   .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } However, most of the times, serialization is a safe operation that can be done synchronously. In fact, many of the serializer classes you will find in the .NET framework only provide sync methods. So the question is, how you can transform that synchronous work into a Task ?. Creating a new task using the method Task.Factory.StartNew for doing all the serialization work would be probably the typical answer. That would work, as a new task is going to be scheduled. However, that might involve some unnecessary context switches, which are out of our control and might be affect performance on server code specially.   If you take a look at the source code of the MediaTypeFormatters shipped as part of the framework, you will notice that they actually using another pattern, which uses a TaskCompletionSource class. public Task WriteToStreamAsync(Type type, object value, Stream writeStream, HttpContent content, TransportContext transportContext) {   var tsc = new TaskCompletionSource<AsyncVoid>(); tsc.SetResult(default(AsyncVoid));   //Do all the serialization work here synchronously   return tsc.Task; }   /// <summary> /// Used as the T in a "conversion" of a Task into a Task{T} /// </summary> private struct AsyncVoid { } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } They are basically doing all the serialization work synchronously and using a TaskCompletionSource for returning a task already done. To conclude this post, this is another approach you might want to consider when using serializers that are not compatible with an async model. Update: Henrik Nielsen from the ASP.NET team pointed out the existence of a built-in media type formatter for writing sync formatters. BufferedMediaTypeFormatter http://t.co/FxOfeI5x

  Read the article

• Is this how dynamic language copes with dynamic requirement?

  - by Amumu

  The question is in the title. I want to have my thinking verified by experienced people. You can add more or disregard my opinion, but give me a reason. Here is an example requirement: Suppose you are required to implement a fighting game. Initially, the game only includes fighters, who can attack each other. Each fighter can punch, kick or block incoming attacks. Fighters can have various fighting styles: Karate, Judo, Kung Fu... That's it for the simple universe of the game. In an OO like Java, it can be implemented similar to this way: abstract class Fighter { int hp, attack; void punch(Fighter otherFighter); void kick(Fighter otherFighter); void block(Figther otherFighter); }; class KarateFighter extends Fighter { //...implementation...}; class JudoFighter extends Fighter { //...implementation... }; class KungFuFighter extends Fighter { //...implementation ... }; This is fine if the game stays like this forever. But, somehow the game designers decide to change the theme of the game: instead of a simple fighting game, the game evolves to become a RPG, in which characters can not only fight but perform other activities, i.e. the character can be a priest, an accountant, a scientist etc... At this point, to make it more generic, we have to change the structure of our original design: Fighter is not used to refer to a person anymore; it refers to a profession. The specialized classes of Fighter (KaraterFighter, JudoFighter, KungFuFighter) . Now we have to create a generic class named Person. However, to adapt this change, I have to change the method signatures of the original operations: class Person { int hp, attack; List<Profession> skillSet; }; abstract class Profession {}; class Fighter extends Profession { void punch(Person otherFighter); void kick(Person otherFighter); void block(Person otherFighter); }; class KarateFighter extends Fighter { //...implementation...}; class JudoFighter extends Fighter { //...implementation... }; class KungFuFighter extends Fighter { //...implementation ... }; class Accountant extends Profession { void calculateTax(Person p) { //...implementation...}; void calculateTax(Company c) { //...implementation...}; }; //... more professions... Here are the problems: To adapt to the method changes, I have to fix the places where the changed methods are called (refactoring). Every time a new requirement is introduced, the current structural design has to be broken to adapt the changes. This leads to the first problem. Rigid structure makes it hard for code reuse. A function can only accept the predefined types, but it cannot accept future unknown types. A written function is bound to its current universe and has no way to accommodate to the new types, without modifications or rewrite from scratch. I see Java has a lot of deprecated methods. OO is an extreme case because it has inheritance to add up the complexity, but in general for statically typed language, types are very strict. In contrast, a dynamic language can handle the above case as follow: ;;fighter1 punch fighter2 (defun perform-punch (fighter1 fighter2) ...implementation... ) ;;fighter1 kick fighter2 (defun perform-kick (fighter1 fighter2) ...implementation... ) ;;fighter1 blocks attacks from fighter2 (defun perform-block (fighter1 fighter2) ...implementation... ) fighter1 and fighter2 can be anything as long as it has the required data for calculation; or methods (duck typing). You don't have to change from the type Fighter to Person. In the case of Lisp, because Lisp only has a single data structure: list, it's even easier to adapt to changes. However, other dynamic languages can have similar behaviors as well. I work primarily with static languages (mainly C and Java, but working with Java was a long time ago). I started learning Lisp and some other dynamic languages this year. I can see how it helps improving my productivity.

  Read the article

• .NET Security Part 4

  - by Simon Cooper

  Finally, in this series, I am going to cover some of the security issues that can trip you up when using sandboxed appdomains. DISCLAIMER: I am not a security expert, and this is by no means an exhaustive list. If you actually are writing security-critical code, then get a proper security audit of your code by a professional. The examples below are just illustrations of the sort of things that can go wrong. 1. AppDomainSetup.ApplicationBase The most obvious one is the issue covered in the MSDN documentation on creating a sandbox, in step 3 – the sandboxed appdomain has the same ApplicationBase as the controlling appdomain. So let’s explore what happens when they are the same, and an exception is thrown. In the sandboxed assembly, Sandboxed.dll (IPlugin is an interface in a partially-trusted assembly, with a single MethodToDoThings on it): public class UntrustedPlugin : MarshalByRefObject, IPlugin { // implements IPlugin.MethodToDoThings() public void MethodToDoThings() { throw new EvilException(); } } [Serializable] internal class EvilException : Exception { public override string ToString() { // show we have read access to C:\Windows // read the first 5 directories Console.WriteLine("Pwned! Mwuahahah!"); foreach (var d in Directory.EnumerateDirectories(@"C:\Windows").Take(5)) { Console.WriteLine(d.FullName); } return base.ToString(); } } And in the controlling assembly: // what can possibly go wrong? AppDomainSetup appDomainSetup = new AppDomainSetup { ApplicationBase = AppDomain.CurrentDomain.SetupInformation.ApplicationBase } // only grant permissions to execute // and to read the application base, nothing else PermissionSet restrictedPerms = new PermissionSet(PermissionState.None); restrictedPerms.AddPermission( new SecurityPermission(SecurityPermissionFlag.Execution)); restrictedPerms.AddPermission( new FileIOPermission(FileIOPermissionAccess.Read, appDomainSetup.ApplicationBase); restrictedPerms.AddPermission( new FileIOPermission(FileIOPermissionAccess.pathDiscovery, appDomainSetup.ApplicationBase); // create the sandbox AppDomain sandbox = AppDomain.CreateDomain("Sandbox", null, appDomainSetup, restrictedPerms); // execute UntrustedPlugin in the sandbox // don't crash the application if the sandbox throws an exception IPlugin o = (IPlugin)sandbox.CreateInstanceFromAndUnwrap("Sandboxed.dll", "UntrustedPlugin"); try { o.MethodToDoThings() } catch (Exception e) { Console.WriteLine(e.ToString()); } And the result? Oops. We’ve allowed a class that should be sandboxed to execute code with fully-trusted permissions! How did this happen? Well, the key is the exact meaning of the ApplicationBase property: The application base directory is where the assembly manager begins probing for assemblies. When EvilException is thrown, it propagates from the sandboxed appdomain into the controlling assembly’s appdomain (as it’s marked as Serializable). When the exception is deserialized, the CLR finds and loads the sandboxed dll into the fully-trusted appdomain. Since the controlling appdomain’s ApplicationBase directory contains the sandboxed assembly, the CLR finds and loads the assembly into a full-trust appdomain, and the evil code is executed. So the problem isn’t exactly that the sandboxed appdomain’s ApplicationBase is the same as the controlling appdomain’s, it’s that the sandboxed dll was in such a place that the controlling appdomain could find it as part of the standard assembly resolution mechanism. The sandbox then forced the assembly to load in the controlling appdomain by throwing a serializable exception that propagated outside the sandbox. The easiest fix for this is to keep the sandbox ApplicationBase well away from the ApplicationBase of the controlling appdomain, and don’t allow the sandbox permissions to access the controlling appdomain’s ApplicationBase directory. If you do this, then the sandboxed assembly can’t be accidentally loaded into the fully-trusted appdomain, and the code can’t be executed. If the plugin does try to induce the controlling appdomain to load an assembly it shouldn’t, a SerializationException will be thrown when it tries to load the assembly to deserialize the exception, and no damage will be done. 2. Loading the sandboxed dll into the application appdomain As an extension of the previous point, you shouldn’t directly reference types or methods in the sandboxed dll from your application code. That loads the assembly into the fully-trusted appdomain, and from there code in the assembly could be executed. Instead, pull out methods you want the sandboxed dll to have into an interface or class in a partially-trusted assembly you control, and execute methods via that instead (similar to the example above with the IPlugin interface). If you need to have a look at the assembly before executing it in the sandbox, either examine the assembly using reflection from within the sandbox, or load the assembly into the Reflection-only context in the application’s appdomain. The code in assemblies in the reflection-only context can’t be executed, it can only be reflected upon, thus protecting your appdomain from malicious code. 3. Incorrectly asserting permissions You should only assert permissions when you are absolutely sure they’re safe. For example, this method allows a caller read-access to any file they call this method with, including your documents, any network shares, the C:\Windows directory, etc: [SecuritySafeCritical] public static string GetFileText(string filePath) { new FileIOPermission(FileIOPermissionAccess.Read, filePath).Assert(); return File.ReadAllText(filePath); } Be careful when asserting permissions, and ensure you’re not providing a loophole sandboxed dlls can use to gain access to things they shouldn’t be able to. Conclusion Hopefully, that’s given you an idea of some of the ways it’s possible to get past the .NET security system. As I said before, this post is not exhaustive, and you certainly shouldn’t base any security-critical applications on the contents of this blog post. What this series should help with is understanding the possibilities of the security system, and what all the security attributes and classes mean and what they are used for, if you were to use the security system in the future.

  Read the article

• Local LINQtoSQL Database For Your Windows Phone 7 Application

  - by Tim Murphy

  There aren’t many applications that are of value without having some for of data store.  In Windows Phone development we have a few options.  You can store text directly to isolated storage.  You can also use a number of third party libraries to create or mimic databases in isolated storage.  With Mango we gained the ability to have a native .NET database approach which uses LINQ to SQL.  In this article I will try to bring together the components needed to implement this last type of data store and fill in some of the blanks that I think other articles have left out. Defining A Database The first things you are going to need to do is define classes that represent your tables and a data context class that is used as the overall database definition.  The table class consists of column definitions as you would expect.  They can have relationships and constraints as with any relational DBMS.  Below is an example of a table definition. First you will need to add some assembly references to the code file. using System.ComponentModel;using System.Data.Linq;using System.Data.Linq.Mapping; You can then add the table class and its associated columns.  It needs to implement INotifyPropertyChanged and INotifyPropertyChanging.  Each level of the class needs to be decorated with the attribute appropriate for that part of the definition.  Where the class represents the table the properties represent the columns.  In this example you will see that the column is marked as a primary key and not nullable with a an auto generated value. You will also notice that the in the column property’s set method It uses the NotifyPropertyChanging and NotifyPropertyChanged methods in order to make sure that the proper events are fired. [Table]public class MyTable: INotifyPropertyChanged, INotifyPropertyChanging{ public event PropertyChangedEventHandler PropertyChanged; private void NotifyPropertyChanged(string propertyName) { if(PropertyChanged != null) { PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); } } public event PropertyChangingEventHandler PropertyChanging; private void NotifyPropertyChanging(string propertyName) { if(PropertyChanging != null) { PropertyChanging(this, new PropertyChangingEventArgs(propertyName)); } } private int _TableKey; [Column(IsPrimaryKey = true, IsDbGenerated = true, DbType = "INT NOT NULL Identity", CanBeNull = false, AutoSync = AutoSync.OnInsert)] public int TableKey { get { return _TableKey; } set { NotifyPropertyChanging("TableKey"); _TableKey = value; NotifyPropertyChanged("TableKey"); } } The last part of the database definition that needs to be created is the data context.  This is a simple class that takes an isolated storage location connection string its constructor and then instantiates tables as public properties. public class MyDataContext: DataContext{ public MyDataContext(string connectionString): base(connectionString) { MyRecords = this.GetTable<MyTable>(); } public Table<MyTable> MyRecords;} Creating A New Database Instance Now that we have a database definition it is time to create an instance of the data context within our Windows Phone app.  When your app fires up it should check if the database already exists and create an instance if it does not.  I would suggest that this be part of the constructor of your ViewModel. db = new MyDataContext(connectionString);if(!db.DatabaseExists()){ db.CreateDatabase();} The next thing you have to know is how the connection string for isolated storage should be constructed.  The main sticking point I have found is that the database cannot be created unless the file mode is read/write.  You may have different connection strings but the initial one needs to be similar to the following. string connString = "Data Source = 'isostore:/MyApp.sdf'; File Mode = read write"; Using you database Now that you have done all the up front work it is time to put the database to use.  To make your life a little easier and keep proper separation between your view and your viewmodel you should add a couple of methods to the viewmodel.  These will do the CRUD work of your application.  What you will notice is that the SubmitChanges method is the secret sauce in all of the methods that change data. private myDataContext myDb;private ObservableCollection<MyTable> _viewRecords;public ObservableCollection<MyTable> ViewRecords{ get { return _viewRecords; } set { _viewRecords = value; NotifyPropertyChanged("ViewRecords"); }}public void LoadMedstarDbData(){ var tempItems = from MyTable myRecord in myDb.LocalScans select myRecord; ViewRecords = new ObservableCollection<MyTable>(tempItems);}public void SaveChangesToDb(){ myDb.SubmitChanges();}public void AddMyTableItem(MyTable newScan){ myDb.LocalScans.InsertOnSubmit(newScan); myDb.SubmitChanges();}public void DeleteMyTableItem(MyTable newScan){ myDb.LocalScans.DeleteOnSubmit(newScan); myDb.SubmitChanges();} Updating existing database What happens when you need to change the structure of your database?  Unfortunately you have to add code to your application that checks the version of the database which over time will create some pollution in your codes base.  On the other hand it does give you control of the update.  In this example you will see the DatabaseSchemaUpdater in action.  Assuming we added a “Notes” field to the MyTable structure, the following code will check if the database is the latest version and add the field if it isn’t. if(!myDb.DatabaseExists()){ myDb.CreateDatabase();}else{ DatabaseSchemaUpdater dbUdater = myDb.CreateDatabaseSchemaUpdater(); if(dbUdater.DatabaseSchemaVersion < 2) { dbUdater.AddColumn<MyTable>("Notes"); dbUdater.DatabaseSchemaVersion = 2; dbUdater.Execute(); }} Summary This approach does take a fairly large amount of work, but I think the end product is robust and very native for .NET developers.  It turns out to be worth the investment. del.icio.us Tags: Windows Phone,Windows Phone 7,LINQ to SQL,LINQ,Database,Isolated Storage

  Read the article

• Plagued by multithreaded bugs

  - by koncurrency

  On my new team that I manage, the majority of our code is platform, TCP socket, and http networking code. All C++. Most of it originated from other developers that have left the team. The current developers on the team are very smart, but mostly junior in terms of experience. Our biggest problem: multi-threaded concurrency bugs. Most of our class libraries are written to be asynchronous by use of some thread pool classes. Methods on the class libraries often enqueue long running taks onto the thread pool from one thread and then the callback methods of that class get invoked on a different thread. As a result, we have a lot of edge case bugs involving incorrect threading assumptions. This results in subtle bugs that go beyond just having critical sections and locks to guard against concurrency issues. What makes these problems even harder is that the attempts to fix are often incorrect. Some mistakes I've observed the team attempting (or within the legacy code itself) includes something like the following: Common mistake #1 - Fixing concurrency issue by just put a lock around the shared data, but forgetting about what happens when methods don't get called in an expected order. Here's a very simple example: void Foo::OnHttpRequestComplete(statuscode status) { m_pBar->DoSomethingImportant(status); } void Foo::Shutdown() { m_pBar->Cleanup(); delete m_pBar; m_pBar=nullptr; } So now we have a bug in which Shutdown could get called while OnHttpNetworkRequestComplete is occuring on. A tester finds the bug, captures the crash dump, and assigns the bug to a developer. He in turn fixes the bug like this. void Foo::OnHttpRequestComplete(statuscode status) { AutoLock lock(m_cs); m_pBar->DoSomethingImportant(status); } void Foo::Shutdown() { AutoLock lock(m_cs); m_pBar->Cleanup(); delete m_pBar; m_pBar=nullptr; } The above fix looks good until you realize there's an even more subtle edge case. What happens if Shutdown gets called before OnHttpRequestComplete gets called back? The real world examples my team has are even more complex, and the edge cases are even harder to spot during the code review process. Common Mistake #2 - fixing deadlock issues by blindly exiting the lock, wait for the other thread to finish, then re-enter the lock - but without handling the case that the object just got updated by the other thread! Common Mistake #3 - Even though the objects are reference counted, the shutdown sequence "releases" it's pointer. But forgets to wait for the thread that is still running to release it's instance. As such, components are shutdown cleanly, then spurious or late callbacks are invoked on an object in an state not expecting any more calls. There are other edge cases, but the bottom line is this: Multithreaded programming is just plain hard, even for smart people. As I catch these mistakes, I spend time discussing the errors with each developer on developing a more appropriate fix. But I suspect they are often confused on how to solve each issue because of the enormous amount of legacy code that the "right" fix will involve touching. We're going to be shipping soon, and I'm sure the patches we're applying will hold for the upcoming release. Afterwards, we're going to have some time to improve the code base and refactor where needed. We won't have time to just re-write everything. And the majority of the code isn't all that bad. But I'm looking to refactor code such that threading issues can be avoided altogether. One approach I am considering is this. For each significant platform feature, have a dedicated single thread where all events and network callbacks get marshalled onto. Similar to COM apartment threading in Windows with use of a message loop. Long blocking operations could still get dispatched to a work pool thread, but the completion callback is invoked on on the component's thread. Components could possibly even share the same thread. Then all the class libraries running inside the thread can be written under the assumption of a single threaded world. Before I go down that path, I am also very interested if there are other standard techniques or design patterns for dealing with multithreaded issues. And I have to emphasize - something beyond a book that describes the basics of mutexes and semaphores. What do you think? I am also interested in any other approaches to take towards a refactoring process. Including any of the following: Literature or papers on design patterns around threads. Something beyond an introduction to mutexes and semaphores. We don't need massive parallelism either, just ways to design an object model so as to handle asynchronous events from other threads correctly. Ways to diagram the threading of various components, so that it will be easy to study and evolve solutions for. (That is, a UML equivalent for discussing threads across objects and classes) Educating your development team on the issues with multithreaded code. What would you do?

  Read the article

• How do I calculate the amount of tuning needed for my server ?

  - by Low Kian Seong

  I have a server which is running a few discrete Python, Java application which most of the time imports data into a PostGreSQL database. I would like to know from people out there who have experience tuning enterprise grade servers how do i go about calculating in a holistic way the amount of tuning needed for my server for example vm.swappiness, vm.overcommit_ratio and other numerical tunings needed for my server. I tried to enable sar on my server to capture daily numbers but these are more along the lines of total numbers and I can't figure out how to allocate memory for my applications. Help would be appreciated. Thanks.

  Read the article

• Is there a way to communicate DBMS with raw memory block or binaries

  - by darkcminor

  I am trying to communicate a numerical matrix operations library like LAPACK with any DBMS. Is it possible to send/receive complete matrices as binary or as a direct memory pointers to process them (it will be something like: The Outside library processes data stored in DBMS, then it computes some huge matrix stuff and then via memory block or a binary DBMS get the result from library)? The main purpose is speed and avoid passing through a flat file, and last but not least, use library toefficiently do some operations DBMS are not designed to. * Is it possible that Oracle, SQL Server, MySQL support this technique?.

  Read the article

• File corruption when copying different file on raid 1

  - by Stephan

  I have a RAID 1 configuration of 2 1TB drives on a Fedora 12 box. Most of what is stored there are video files that are numerical labeled. The problem I'm having is that I had one of the video files get corrupted. I copied a replacement from a backup and replaced the bad file and now it works fine. However, after doing this the next numbered file goes from 350MB to 200KB and all but about .5 second of video disappears. If I then replace that file it happens to the next one down the line. Ex: Replace corrupt file 1.avi and file 2.avi shrinks to 200KB. Replace now corrupted 2.avi and it works but 3.avi gets screwed up. I have run SMART tests on the drives and they report fine. Does anyone have any tests I can run to try to figure out what is going on? EDIT: It is a two disk software RAID 1 with an ext4 filesystem

  Read the article

• Asus EEE PC 1005HA (XP Home) refuses to connect to Virgin Mobile MiFi

  - by Dennis Wurster

  My client has an Asus EEE PC model 1005HA, and we're attempting to connect it to the WiFi network created by a VirginMobile MiFi unit. They also have a MacBook Pro with Snow Leopard that has absolutely no issue connecting to the MiFi. The specific symptom is that the netbook fails to lease an IP address from the MiFi unit. I supply the 12-digit numerical password (WPA) to the netbook, it throws a 'waiting for network' dialog with an indeterminate progress indicator, and then times out. Update: We've determined that this behavior has stopped when the EEE PC and the MiFi unit were taken out of the client's home, and to a different home that didn't have an existing wifi network. Similarly, when taken to a third location that didn't have wifi, the EEE PC and MiFi got along swimmingly. My current theory is that the existing wifi networks and the wifi leg of the MiFi unit are on the same channel and competing with one another. Perhaps the MacBook Pro has the capability to overcome this interference, while the EEE PC doesn't.

  Read the article

• Extract part of a image from a big image

  - by rajat

  I have a 6 images , and each image has a certain section that i want to save as a separate image , the problem is that it has to be accurate because i am doing some animation using the sub-image so they should exactly . so I want to accurately extract a that part from each of the 6 images , i can't do it using a image editor in which i have to make the bounding box myself because it will not be accurate , is there any program that lets me do this by like defining a box using numerical values. PS: I don't want to write matlab or opencv program for this .

  Read the article

• Set an Excel cell's color based on multiple other cells' colors

  - by Lord Torgamus

  I have an Excel 2007 spreadsheet for a list of products and a bunch of factors to rate each one on, and I'm using Conditional Formatting to set the color of the cells in the individual attribute columns. It looks something like this: I want to fill in the rating column for each item with a color, based on the color ratings of its individual attributes. Examples of ways to determine this: the color of the category in which the item scored worst the statistical mode of the category colors the average of the category ratings, where each color is assigned a numerical value How can I implement any or all of the above rules? (I'm really just asking for a quick overview of the relevant Excel feature; I don't need step-by-step instructions for each rule.)

  Read the article

• What's the advantage of using a bash script for cron jobs?

  - by AlxVallejo

  From my understanding you can write your crons by editing crontab -e I've found several sources that instead refer to a bash script in the cron job, rather than writing a job line for line. Is the only benefit that you can consolidate many tasks into one cron job using a bash script? Additional question for a newbie: Editing crontab -e refers to one file correct? I've noticed that if I open crontab -e and close without editing, when I open the file again there is a different numerical extension such as: "/tmp/crontab.XXXXk1DEaM" 0L, 0C I though the crontab is stored in /var/spool/cron or /etc/crontab ?? Why would it store the cron in the tmp folder?

  Read the article

• Asterisk Register username with special character like "@"

  - by Najibul Huq

  I am using a SIP provider that has provided me with a username like: [email protected] (Note this is only the username part) And has a numerical password. My Register string looks something like this: [email protected]:[email protected] But this is not working, as asterisk is only sending the first part +112223344 before the first @. My provider is adamant about having the full form of it. This is the first time I am facing this issue that is quite unusual for me. Please help.

  Read the article

• Clone/mirror a textbox in a PDF form

  - by Tim Pietzcker

  I've got a PDF form in Acrobat X Pro where users can enter their name in a textbox on the first page. I would like the contents of that box to be cloned/mirrored in another box on the second page of the same form: However, in the Properties dialog of the second textbox, I can't find a way to reference the first one. I do have options to calculate numerical values and perform validation etc. etc., but I can't seem to simply have it display the contents of another textbox. Is this not possible in PDF forms, or am I overlooking something obvious?

  Read the article

• Add Free Windows Live Apps to Your Website or Blog

  - by Matthew Guay

  Would you like to use Hotmail, Office Web Apps, Messenger, and more on your website domain?  Here’s how you can add Windows Live to your website for free. Microsoft offers a popular suite of online communications products including Hotmail and Messenger.  Although Hotmail hasn’t been as popular in recent years as Gmail, it is getting a refresh this summer that might make it an even better email solution.  Additionally, the new Office Web Apps offer great compatibility with Office documents. While Skydrive offers 25Gb of free online file storage for all users, so Windows Live can make a great communications solution for your domain. Note: To signup for Windows Live for your domain, you will need to be able to add info to your WordPress.com blog or change Domain settings manually. Getting Started Open the Windows Live Custom Domains page (Link below) to get started adding Windows Live to your domain.  Your free Windows Live account will let you create up to 500 accounts, so it’s great for teams and groups that want to have customized email addresses in addition to those who just want an email account for their website. Enter your domain or subdomain you want to add to Windows Live in the box, and then select whether you want to setup Hotmail with this or now.  We want to add email to our domain, so select Set up Windows Live Hotmail for my domain and click Continue. You’ll need to sign in with a Windows Live ID to create the account, or choose to create a new Windows Live account associated with your domain.   Sign in with your Windows Live ID…this can be a Hotmail, Live Messenger, XBOX Live, Zune ID, or Microsoft.com account. Or, enter your information to create a new Windows Live ID if you selected the second option. Now, review your settings and make sure everything looks correct.  Click the I Accept button to setup your account.   Your account is now fully setup, but you’ll need to add or edit DNS information on your site.  The steps are slightly different depending if your site is hosted on WordPress.com, on your own server, or hosting service. We’ll show you how to do it on either one. First, though, note the information below this box.  You’ll see settings for your Mail setup…   Security settings…   And Messenger integration.  Make note of the settings, especially the circled ones, as we’ll need them in the next step. Integrate Windows Live with Your WordPress Blog If the domain you added to Windows Live is for your WordPress blog, login to your WordPress dashboard in a separate browser window or tab.  Click the arrow beside Upgrades, and select Domains from the menu. Click the Edit DNS link beside the domain name you’re adding to Windows Live. In the text box on this page, enter the following, replacing Your_info with your code from the Mail Setup box in your Windows Live Dashboard.  Note that this is the blurred section in our screenshots.  It should be a numerical code like 1234567890.pamx1.hotmail.com. MX 10 Your_info.pamx1.hotmail.com. TXT v=spf1 include:hotmail.com ~all CNAME Your_info domains.live.com. Click Save DNS records, and your settings are saved to WordPress.  Note that this will only integrate email with your WordPress account; you cannot integrate Messenger with a domain hosted on WordPress.com. Finally, return to your Windows Live Settings page and click Refresh.  If your settings are correct, you’ll now be ready to use Windows Live on your WordPress.com domain. Integrate Windows Live with Your Own Server If your website is hosted on your own server or hosting account, you’ll need to take a few more steps to add Windows Live to your domain.  This is fairly easy, but the steps may be different depending on your hosting company or registrar.  With some hosts, you may have to contact support to have them add the MX records for you.  Our site’s host uses the popular cPanel for website administration, so here’s how we added the MX Entries through cPanel. Login to your website’s cPanel, and select MX Entry under the Mail section. In the text box on this page, enter the following, replacing Your_info with your code from the Mail Setup box in your Windows Live Dashboard.  Note that this is the blurred section in our screenshots.  It should be a numerical code like 1234567890.pamx1.hotmail.com. MX 10 Your_info.pamx1.hotmail.com. Now, go back to your cPanel home, and select Advanced DNS Zone Editor under Domains. Here, add a TXT record with the following info: Name: yoursite.com. TTL: 3600 TXT Data: v=spf1 include:hotmail.com ~all Click Add Record and your Mail integration data is all configured. To integrate Messenger with your own domain, you’ll have to add an SRV entry to your DNS settings.  cPanel doesn’t have an option for this, so we had to contact our site’s hosting company and they added the entry for us.  Copy all of the information in the Messenger box and send it to your domain support, and they should be able to add this for you.  Alternately, if you don’t want or need Messenger, then you can simply skip this step. Once all of your settings are in place, return to your Windows Live Settings page and click Refresh.  If your settings are correct, you’ll now be ready to use Windows Live on your WordPress.com domain. Create a New Email Account On Your Domain Welcome to your new Windows Live admin page!  Now you can add email accounts so you and anyone else you want can access Hotmail and the other Windows Live apps with your domain.  Click Add to add an account. Enter an account name, which will be the email address of the account, e.g. [email protected].  Then enter the user’s name and a password for the account.  By default this will be a temporary password, and the user will have to change it on first log-in, but if you’re setting up this account for yourself, you can uncheck the box and keep this as your standard password. Now, go to www.mail.live.com, and sign in with your new email address and password.  Remember, your email address is your username previously entered followed by @yourdomain.com. To finish setting up the email account, enter your password, secret question and answer, alternate email, and location information.  Click I accept to finish setting up your new email account. Enter the characters in the Captcha to confirm you’re a human, and click Continue. Your new Hotmail inbox will now load, and you’ll have a welcome email in your inbox.  This works the same as normal Hotmail, except this time, your email address is with your own domain. You can now access any of the Windows Live services from the top-level menu. Here’s an Excel Spreadsheet open in the new Office Web Apps via SkyDrive on our new Windows Live account. If you setup Messenger access previously, you can now sign in to Windows Live Messenger using your new @yourdomain.com account as well. Important Links Accessing your Windows Live accounts is easy.  Simply go to any Windows Live site, such as www.hotmail.com or www.skydrive.com, and sign in with your new Windows Live ID from your domain as normal.  You don’t need a special address to access your account; it works just like the standard public Hotmail accounts. To administer your Windows Live for your domain, go to https://domains.live.com/ and sign in with the Windows Live ID you used to create the account.  Here you can add more users, change settings, and view usage details for the Windows Live accounts on your domain. Conclusion Windows Live is easy to add to your domain, and lets you create up to 500 email address for it.  With the upcoming updates to Hotmail and Office Web Apps coming this summer, this can be a nice way to make your domain even more useful.  And with 500 email accounts, you can easily let your team take advantage of your unique address as well. If you’d rather use Google’s online applications with your domain, check out our article on how to add free Google apps to your website or blog. Link Signup for Windows Live for Your Domain Similar Articles Productive Geek Tips Tools to Help Post Content On Your WordPress BlogBackup Your Windows Live Writer SettingsInstall Windows Live Essentials In Windows 7Add Your Gmail To Windows Live MailMysticgeek Blog: A Look at Internet Explorer 8 Beta 1 on Windows XP TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips HippoRemote Pro 2.2 Xobni Plus for Outlook All My Movies 5.9 CloudBerry Online Backup 1.5 for Windows Home Server Backup Drivers With Driver Magician TubeSort: YouTube Playlist Organizer XPS file format & XPS Viewer Explained Microsoft Office Web Apps Guide Know if Someone Accessed Your Facebook Account Shop for Music with Windows Media Player 12

  Read the article

• Box 2d basic questions

  - by philipp

  I am a bit new to box2d and I am developing an game with type and letters. I am using an svg font and generate the box2d bodies direct from the glyphs path definition, using the convex hull of them. I also have an decomposition routine the decomposes this hull if necessary. All this it is more or less working, except that I got some strange errors which definitely are caused by the scale factors. The problem is caused by two factors: first: the world scale of box2d, second: the the precision of curve-approximation of the glyph vectors. So through scaling down the input vertices for box2d, it happens that they become equal caused by numerical precision, what causes errors in box2d. Through scaling the my glyphs a bit up, this goes away. I also goes away if I chose a different world scale factor, but this slows down the whole animation quite much! So if my view port is about 990px * 600px and i want to animate Glyphs in box2d which should have a size from about 50px * 50px up to 300px * 300px, which scale factor of the b2world should i choose? How small should the smallest distance from on vertex to another be, while approximating the glyph vectors? Thanks for help greetings philipp EDIT:: I continued reading the docs of box2d and after rethinking of the units system, which is designed to handle object from 0.1 up to 10 meters, I calculated a scale factor of 75. So Objects 600px width will are 8 meters wide in box2d and even small objects of about 20px width will become 0.26 meters width in box2d. I will go on trying with this values, but if there is somebody out there who could give me a clever advice i would be happy!

  Read the article

• CodePlex Daily Summary for Wednesday, April 14, 2010

  CodePlex Daily Summary for Wednesday, April 14, 2010New Projectsbitly.net: A bitly (useing Version 3 of their API's) client for .NET (Version 3.5)Chord Sheet Editor Add-In for Word: Transpose music chord sheets (guitar chord sheets, etc.) in Microsoft Word using this VSTO Add-In.CloudSponge.Net: Simple .Net wrapper for www.cloudsponge.com's REST API.Database Searcher: This is a small tool for searching a typed value inside all type matching columns and rows of a database. For connecting the database a .NET data p...Edu Math: PL: Program Edu Math, ma na celu ułatwienie wykonywania skomplikowanych obliczeń oraz analiz matematycznych. EN: Program Edu Math, aims to facilita...fluent AOP: This project is not yet publishedFNA Fractal Numerical Algorithm for a new encryption technology: FNA Fractal Numerical Algorithm for a new encryption technology is a symmetrical encryption method based on two algorithms that I developed for: 1....Image viewer cum editor: This is a project on image viewing and editing. The project have following features VIEWER: Album Password security for albums Inbuilt Browser...JEngine - Tile Map Editor v1: JEngine - Tile Map Editor v1Jeremy Knight: Code samples, snippets, etc from my personal blog.lcskey: lcs test codemoldme: testesds ssdfsdfsNanoPrompt: NanoPrompt makes it more pleasant to work on a command-line. Features: - syntax-highlighting - graphical output possible - up to 12 "displays" (cha...nirvana: for testOffInvoice Add-in for MS Office 2010: Project Description: The project it's based in the ability to extend funtionality in the Microsoft Office 2010 suite.PowerSlim - Acceptance Testing for Enterprise Applications: PowerSlim makes it possible to use PowerShell in the acceptance testing. It is a small but powerful plugin for the Fitnesse acceptance testing fram...Proxi [Proxy Interface]: Proxi is a light-weight library that allows to generate dynamic proxies using different providers. By utilizing Proxi frameworks and libraries can ...Reality show about ASP.NET development: This application is created with using ASP.NET and Microsoft SQL Server for the demo purposes with the following target goals: example of usage fo...RecordLogon.vbs login script: RecordLogon.vbs is a script applied at logon via Group or Local policy. It records specific user and computer information and writes the data to a ...SpaceGameApplet: A java game ;)SpaceShipsGame: A game with space ships ";..;"SysHard: Info for Linux system.System Etheral™ - Developer: SE Dev (System Etheral™ - Developer) is an OS (Operating System) that is a bit like UNIX but it is for you to edit! We have not gave you much but w...TimeSheet Reporting Silverlight: TimeSheet Reporting application in Silver light. Contains a data grid containing combo boxes bound to different data sources like Members and Proje...TrayBird: A minimalistic twitter client for windows.Twitter4You: This appliction for windows is a communication for twitter!WCF RIA Services (+ PRISM + MVVM) LoB Application: WCF RIA Services sample LoB application (case study) built on PRISM with Entity Framework Model. It's a simple application for a fictive company Te...New ReleasesBluetooth Radar: Version 1.9: Change Search and Close Icons Add Device Detail ViewCloudSponge.Net: Alpha: Initial alpha release very limited tested includes *CloudSponge.dll *Sponge.exe (simple cmd line utility to import contacts, and test API)Global Assembly Cache comparison tool: GAC Compare version 3.1: Version 3.1Added export assemblies to directory functionalityHTML Ruby: 6.21.2: Some style adjustments Ruby text spacing is spaced out to keep Firefox responsive Status bar is backJEngine - Tile Map Editor v1: JEngine - Tile Map Editor V1: JEngine - Tile Map Editor V1 Discription SoonJeremy Knight: SQL Padding Functions v1.0: The entire scripts, including if exists logic, for SQL Padding Functions are included in this download.jqGrid ASP.Net MVC Control: Version 1.1.0.0: UPDATE 14-04 Fixed a small problem with the custom column renderers controller, And added a new example for a cascading-dropdownlist grid column A...JulMar MVVM Helpers + Behaviors: Version 1.06: This version is an update to MVVM Helpers that is built on Visual Studio 2010 RTM. It includes some minor updates to classes and a few new convert...lcskey: v 1.0: v1.0 基本能跑，未详细测试LINQ To Blippr: LINQ to Blippr: Download to test out and play around LINQ to Blippr based from blog posts: http://consultingblogs.emc.com/jonsharrattLINQ to XSD: 1.1.0: The LINQ to XSD technology provides .NET developers with support for typed XML programming. LINQ to XSD contributes to the LINQ project (.NET Langu...LINQ to XSD: 2.0.0: It is the same code as version 1.1 but compiled for .NET framework 4.0. Requirements: .NET Framework 4.0.LocoSync: LocoSync v0.1r2010.04.12: Second Alpha version of LocoSync. Download unzip and run setup. It will download the .NET framework if needed. It will create an icon in the start ...mojoPortal: 2.3.4.2: see release note on mojoportal.com http://www.mojoportal.com/mojoportal-2342-released.aspxNanoPrompt: Setup (.NET 4.0) - 20100414-A Nightly: The setup for NanoPrompt 0.Xa for Intel-80386- (32 or 64 bits) or Intel-Itanium-compatible targets with installed .NET-Framework 4.0 Client Profile...Neural Cryptography in F#: Neural Cryptography 0.0.5: This release provides the basic functionality that this project was supposed to have from the very beginning: it can hash strings using neural netw...NodeXL: Network Overview, Discovery and Exploration for Excel: NodeXL Class Libraries, version 1.0.1.121: The NodeXL class libraries can be used to display network graphs in .NET applications. To include a NodeXL network graph in a WPF desktop or Windo...nRoute Framework: nRoute.Toolkit Release Version 0.4: Note, both "nRoute.Framework (x3)" and "nRoute.Toolkit (x3)" zip files contains binaries for Web, Desktop and Mobile targets. Also this release wa...Numina Application/Security Framework: Numina.Framework Core 50381: Rebuilt using .NET 4 RTM One minor change made to the web.config file - added System.Data.Linq to the assemblies list.PokeIn Comet Ajax Library: PokeIn Lib and Sample: Great sample with usefull comet ajax library! .Net 2.0 Note : It was very easy to build this project with Visual Studio 10 ;)Powershell Zip File Export/Import Cmdlet Module: PowershellZip 0.1.0.3: Powershell-Zip 0.1.0.3 contains the cmdlets Export-Zip and Import-ZipPowerSlim - Acceptance Testing for Enterprise Applications: PowerSlim 0.1: Just PowerSlim. http://vlasenko.org/2010/04/09/howto-setup-powerslim-step-by-step/RDA Collaboration Team Projects: SharePoint BPOS Logging Framework: RDA's SharePoint BPOS logging framework is a very lightweight WSP Builder project that provides the following items: A Site feature that creates a...RecordLogon.vbs login script: LogonSearchGadget: This is the Windows Gadget companion for RecordLogon.RecordLogon.vbs login script: LogonSearchTool.hta: This is the HTA standalone script that runs inside of an IE window. The HTA is what presents the data the recordlogon.vbs creates. Please remember...RecordLogon.vbs login script: recordlogon.vbs: This is the main script that grabs the logon and computer information and dumps the info as text files to a defined folder share. Make sure to chec...Rensea Image Viewer: RIV 0.4.3: New Release of RIV. Added many many features! You would love it. You would need .NET Framework 4.0 to make it run With separated RIV up-loader, to...SharePoint Site Configurator Feature: SharePoint Site Configurator V2.0: Updated for SharePoint 2010 and added quite a lot of new functions. Compatible with SP2010, MOSS and WSS 3.0Sharp Tests Ex: Sharp Tests Ex 1.0.0RC2: Project Description #TestsEx (Sharp Tests Extensions) is a set of extensible extensions. The main target is write short assertions where the Visual...SQL Server Extended Properties Quick Editor: Release 1.6.2: Whats new in 1.6.2: Fixed several errors in LinqToSQL generated classes, solved generation EntitySet members. Its highly recomended to download and...SSRS SDK for PHP: SugarCRM Sample for SSRSReport: The zip file contains a sample SugarCRM module that shows how the SSRS SDK for PHP can be used to add simple reporting capabilities to the SugarCRM...System Etheral™ - Developer: System Etheral Dev v1.00: Comes with a VERY basic text editor and the ability to shutdown. Hopefully we will have a lot more stuff in version 1.01! But this is fine for now....Text to HTML: 0.4.2.0: ¡Gracias a Martin Lemburg por avisar de los errores y por sus sugerencias! Cambios de la versiónSustitución de los caracteres especiales alemanes:...TimeSheet Reporting Silverlight: v1.0 Source Code: Source CodeTwitter4You: Twitter 4 You - Version 1.0 (TESTER): Serialcode: http://joeynl.blogspot.com/2010/04/test-version-of-t4yv1.html Thanks JoeyNLVCC: Latest build, v2.1.30413.0: Automatic drop of latest buildVisioAutomation: VisioAutomation 2.5.1: VisioAutomation 2.5.1- Moved to Visual Studio 2010 (Still using .NET Framework 3.5) Changes Since 2.5.0- Solution and Projects are all based on Vi...Most Popular ProjectsRawrWBFS ManagerAJAX Control ToolkitMicrosoft SQL Server Product Samples: DatabaseSilverlight ToolkitWindows Presentation Foundation (WPF)ASP.NETMicrosoft SQL Server Community & SamplesPHPExcelFacebook Developer ToolkitMost Active ProjectsRawrAutoPocopatterns & practices – Enterprise LibraryGMap.NET - Great Maps for Windows Forms & PresentationFarseer Physics EngineNB_Store - Free DotNetNuke Ecommerce Catalog ModuleBeanProxyjQuery Library for SharePoint Web ServicesBlogEngine.NETFacebook Developer Toolkit

  Read the article

• Mission critical embedded language

  - by Moe

  Maybe the question sounds a bit strange, so i'll explain a the background a little bit. Currently i'm working on a project at y university, which will be a complete on-board software for an satellite. The system is programmed in c++ on top of a real-time operating system. However, some subsystems like the attitude control system and the fault detection and a space simulation are currently only implemented in Matlab/Simulink, to prototype the algorithms efficiently. After their verification, they will be translated into c++. The complete on-board software grew very complex, and only a handful people know the whole system. Furthermore, many of the students haven't program in c++ yet and the manual memory management of c++ makes it even more difficult to write mission critical software. Of course the main system has to be implemented in c++, but i asked myself if it's maybe possible to use an embedded language to implement the subsystem which are currently written in Matlab. This embedded language should feature: static/strong typing and compiler checks to minimize runtime errors small memory usage, and relative fast runtime attitude control algorithms are mainly numerical computations, so a good numeric support would be nice maybe some sort of functional programming feature, matlab/simulink encourage you to use it too I googled a bit, but only found Lua. It looks nice, but i would not use it in mission critical software. Have you ever encountered a situation like this, or do you know any language, which could satisfies the conditions? EDIT: To clarify some things: embedded means it should be able to embed the language into the existing c++ environment. So no compiled languages like Ada or Haskell ;)

  Read the article

• Using Umbraco&rsquo;s Dropdown Datatype

  - by MightyZot

  In Umbraco, you could consider document types like models and data types as property types for those modes. For example, you may create a document type called “Prices” to represent a page that displays a list of prices. And, then, you might create a document type called “Price Item” to represent the price list items. A property called “Price” could then represent the price of an item. When you create the Price property, you specify the data type, which in this case might be “Number”, indicating that this particular field accepts only numerical values. Consequently, you could also create a drop down list property called “Category”, allowing you to categorize the items in your price list. To add items to the drop down list, you modify the data type definition in the Developer module of the Umbraco administrative utility. Instead of modifying the drop down data type itself, you should first make a copy by right-clicking on the Data Types node and choosing Create. Give your new data type a name in the Create dialog and click the Create button. In the Edit datatype dialog, change “Render control” to “Dropdown list”.  To add your list items, simply enter that value into the textbox next to “Add prevalue” and click Save or press the Enter key. Now that you have a new drop down list data type created, along with assigned list items, you can use it in your document type definitions just like you would the other data types.

  Read the article

• Teaching myself, as a physicist, to become a better programmer

  - by user787267

  I've always liked physics, and I've always liked coding, so when I got the offer for a PhD position doing numerical physics (details are not relevant, it's mostly parallel programming for a cluster) at a university, it was a no-brainer for me. However, as most physicists, I'm self taught. I don't have broad background knowledge about how to code in an object oriented way, or the name of that specific algorithm that optimizes the search in some kD tree. Since all my work so far has been more concerned about the physics and the scientific results, I undoubtedly have some bad habits - more so because my coding is my own, and not really teamwork. I have mostly used C since it is very straightforward and "what you write is what you get" - no need for fancy abstractions. However, I have recently switched to C++ since I'd like to learn more about the power that comes with abstraction, and it's pretty C-like (syntax-wise at least). How do I teach myself to code in a good, abstract way like a graduate in computer science? I know my code is efficient, but I want it to be elegant as well, and readable. Keep in mind that I don't have time to read several 1000-page tomes about abstract programming. I need to spend time on actual, physics related research (my supervisor would laugh at me if he knew I spent time thinking about how to program elegantly). How do I assess if my work is also good from a programmer's perspective?

  Read the article

• Solving Big Problems with Oracle R Enterprise, Part I

  - by dbayard

  Abstract: This blog post will show how we used Oracle R Enterprise to tackle a customer’s big calculation problem across a big data set. Overview: Databases are great for managing large amounts of data in a central place with rigorous enterprise-level controls.  R is great for doing advanced computations.  Sometimes you need to do advanced computations on large amounts of data, subject to rigorous enterprise-level concerns.  This blog post shows how Oracle R Enterprise enables R plus the Oracle Database enabled us to do some pretty sophisticated calculations across 1 million accounts (each with many detailed records) in minutes. The problem: A financial services customer of mine has a need to calculate the historical internal rate of return (IRR) for its customers’ portfolios.  This information is needed for customer statements and the online web application.  In the past, they had solved this with a home-grown application that pulled trade and account data out of their data warehouse and ran the calculations.  But this home-grown application was not able to do this fast enough, plus it was a challenge for them to write and maintain the code that did the IRR calculation. IRR – a problem that R is good at solving: Internal Rate of Return is an interesting calculation in that in most real-world scenarios it is impractical to calculate exactly.  Rather, IRR is a calculation where approximation techniques need to be used.  In this blog post, we will discuss calculating the “money weighted rate of return” but in the actual customer proof of concept we used R to calculate both money weighted rate of returns and time weighted rate of returns.  You can learn more about the money weighted rate of returns here: http://www.wikinvest.com/wiki/Money-weighted_return First Steps- Calculating IRR in R We will start with calculating the IRR in standalone/desktop R.  In our second post, we will show how to take this desktop R function, deploy it to an Oracle Database, and make it work at real-world scale.  The first step we did was to get some sample data.  For a historical IRR calculation, you have a balances and cash flows.  In our case, the customer provided us with several accounts worth of sample data in Microsoft Excel.      The above figure shows part of the spreadsheet of sample data.  The data provides balances and cash flows for a sample account (BMV=beginning market value. FLOW=cash flow in/out of account. EMV=ending market value). Once we had the sample spreadsheet, the next step we did was to read the Excel data into R.  This is something that R does well.  R offers multiple ways to work with spreadsheet data.  For instance, one could save the spreadsheet as a .csv file.  In our case, the customer provided a spreadsheet file containing multiple sheets where each sheet provided data for a different sample account.  To handle this easily, we took advantage of the RODBC package which allowed us to read the Excel data sheet-by-sheet without having to create individual .csv files.  We wrote ourselves a little helper function called getsheet() around the RODBC package.  Then we loaded all of the sample accounts into a data.frame called SimpleMWRRData. Writing the IRR function At this point, it was time to write the money weighted rate of return (MWRR) function itself.  The definition of MWRR is easily found on the internet or if you are old school you can look in an investment performance text book.  In the customer proof, we based our calculations off the ones defined in the The Handbook of Investment Performance: A User’s Guide by David Spaulding since this is the reference book used by the customer.  (One of the nice things we found during the course of this proof-of-concept is that by using R to write our IRR functions we could easily incorporate the specific variations and business rules of the customer into the calculation.) The key thing with calculating IRR is the need to solve a complex equation with a numerical approximation technique.  For IRR, you need to find the value of the rate of return (r) that sets the Net Present Value of all the flows in and out of the account to zero.  With R, we solve this by defining our NPV function: where bmv is the beginning market value, cf is a vector of cash flows, t is a vector of time (relative to the beginning), emv is the ending market value, and tend is the ending time. Since solving for r is a one-dimensional optimization problem, we decided to take advantage of R’s optimize method (http://stat.ethz.ch/R-manual/R-patched/library/stats/html/optimize.html). The optimize method can be used to find a minimum or maximum; to find the value of r where our npv function is closest to zero, we wrapped our npv function inside the abs function and asked optimize to find the minimum.  Here is an example of using optimize: where low and high are scalars that indicate the range to search for an answer.   To test this out, we need to set values for bmv, cf, t, emv, tend, low, and high.  We will set low and high to some reasonable defaults. For example, this account had a negative 2.2% money weighted rate of return. Enhancing and Packaging the IRR function With numerical approximation methods like optimize, sometimes you will not be able to find an answer with your initial set of inputs.  To account for this, our approach was to first try to find an answer for r within a narrow range, then if we did not find an answer, try calling optimize() again with a broader range.  See the R help page on optimize()  for more details about the search range and its algorithm. At this point, we can now write a simplified version of our MWRR function.  (Our real-world version is  more sophisticated in that it calculates rate of returns for 5 different time periods [since inception, last quarter, year-to-date, last year, year before last year] in a single invocation.  In our actual customer proof, we also defined time-weighted rate of return calculations.  The beauty of R is that it was very easy to add these enhancements and additional calculations to our IRR package.)To simplify code deployment, we then created a new package of our IRR functions and sample data.  For this blog post, we only need to include our SimpleMWRR function and our SimpleMWRRData sample data.  We created the shell of the package by calling: To turn this package skeleton into something usable, at a minimum you need to edit the SimpleMWRR.Rd and SimpleMWRRData.Rd files in the \man subdirectory.  In those files, you need to at least provide a value for the “title” section. Once that is done, you can change directory to the IRR directory and type at the command-line: The myIRR package for this blog post (which has both SimpleMWRR source and SimpleMWRRData sample data) is downloadable from here: myIRR package Testing the myIRR package Here is an example of testing our IRR function once it was converted to an installable package: Calculating IRR for All the Accounts So far, we have shown how to calculate IRR for a single account.  The real-world issue is how do you calculate IRR for all of the accounts?This is the kind of situation where we can leverage the “Split-Apply-Combine” approach (see http://www.cscs.umich.edu/~crshalizi/weblog/815.html).  Given that our sample data can fit in memory, one easy approach is to use R’s “by” function.  (Other approaches to Split-Apply-Combine such as plyr can also be used.  See http://4dpiecharts.com/2011/12/16/a-quick-primer-on-split-apply-combine-problems/). Here is an example showing the use of “by” to calculate the money weighted rate of return for each account in our sample data set.  Recap and Next Steps At this point, you’ve seen the power of R being used to calculate IRR.  There were several good things: R could easily work with the spreadsheets of sample data we were given R’s optimize() function provided a nice way to solve for IRR- it was both fast and allowed us to avoid having to code our own iterative approximation algorithm R was a convenient language to express the customer-specific variations, business-rules, and exceptions that often occur in real-world calculations- these could be easily added to our IRR functions The Split-Apply-Combine technique can be used to perform calculations of IRR for multiple accounts at once. However, there are several challenges yet to be conquered at this point in our story: The actual data that needs to be used lives in a database, not in a spreadsheet The actual data is much, much bigger- too big to fit into the normal R memory space and too big to want to move across the network The overall process needs to run fast- much faster than a single processor The actual data needs to be kept secured- another reason to not want to move it from the database and across the network And the process of calculating the IRR needs to be integrated together with other database ETL activities, so that IRR’s can be calculated as part of the data warehouse refresh processes In our next blog post in this series, we will show you how Oracle R Enterprise solved these challenges.

  Read the article

• What can be done against language inertia?

  - by gerrit

  Often, projects use programming language X, but would use programming language Y if they were started from scratch. For example, big numerical models may be written entirely in Fortran. Whereas this might be a reasonable choice for the components that need to run fast (alternative would be C or C++), it might be a poor choice for components that either do not need to run fast (such as things dealing with human input or simple visualisations), or where runtime is not the limiting factor (such as I/O, particularly when from the network). Another example may be when a project is built using a propriety language (such as Matlab; no, FOSS clones are not good enough) and was started at a time when FOSS alternatives were not viable, but ten years later, they are; and it would be beneficial to migrate. However, due to language inertia, a migration does not happen. Code that works should not be touched, porting code is a time-consuming, expensive process, and programmers are familiar in language X but not necessarily in language Y. Still, in the long term, a migration would likely be beneficial. Can anything be done to mitigate the problems associated with language inertia? Are there any notable examples of big projects that have successfully overcome this problem? Or is a project bound to stick forever with the initial choices?

  Read the article

• How to boot from toshiba recovery partition after installing ubuntu 14.04.1? [duplicate]

  - by Hunter Dotson

  This question already has an answer here: How to remove Ubuntu and put Windows back on? 14 answers Im new here and have not found a post even close to this so here it is: i installed ubuntu 14.04.1 over my Windows 7 Home Premium installation. didn't loose any important data.skip to when the install is done i tried out ubuntu and got sick of it after a while.(the try ubuntu option was greyed out) i got sick of ubuntu after about an hour and i tried to boot into my recovery partition. That's where im running into trouble: you are supposed to hold down the numerical "0" while turning on the power. but it just proceeds to load grub/ubuntu and does not even try to boot into the recovery partition. "000000000000" is all i get from holding it down I know the recovery partition is intact,but i cant access it,even when setting a boot flag on it. i am stumped and i really need answers thanks in advance! specs Toshiba satellite l775 intel core i3 dual core processor original os:windows 7 home premium 64 bit sp1 let me know if you need more info!

  Read the article

< Previous Page | 107 108 109 110 111 112 113 114 115 116 117 118  | Next Page >