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• Version Assemblies with TFS 2010 Continuous Integration

  - by Steve Michelotti

  When I first heard that TFS 2010 had moved to Workflow Foundation for Team Build, I was *extremely* skeptical. I’ve loved MSBuild and didn’t quite understand the reasons for this change. In fact, given that I’ve been exclusively using Cruise Control for Continuous Integration (CI) for the last 5+ years of my career, I was skeptical of TFS for CI in general. However, after going through the learning process for TFS 2010 recently, I’m starting to become a believer. I’m also starting to see some of the benefits with Workflow Foundation for the overall processing because it gives you constructs not available in MSBuild such as parallel tasks, better control flow constructs, and a slightly better customization story. The first customization I had to make to the build process was to version the assemblies of my solution. This is not new. In fact, I’d recommend reading Mike Fourie’s well known post on Versioning Code in TFS before you get started. This post describes several foundational aspects of versioning assemblies regardless of your version of TFS. The main points are: 1) don’t use source control operations for your version file, 2) use a schema like <Major>.<Minor>.<IncrementalNumber>.0, and 3) do not keep AssemblyVersion and AssemblyFileVersion in sync. To do this in TFS 2010, the best post I’ve found has been Jim Lamb’s post of building a custom TFS 2010 workflow activity. Overall, this post is excellent but the primary issue I have with it is that the assembly version numbers produced are based in a date and look like this: “2010.5.15.1”. This is definitely not what I want. I want to be able to communicate to the developers and stakeholders that we are producing the “1.1 release” or “1.2 release” – which would have an assembly version number of “1.1.317.0” for example. In this post, I’ll walk through the process of customizing the assembly version number based on this method – customizing the concepts in Lamb’s post to suit my needs. I’ll also be combining this with the concepts of Fourie’s post – particularly with regards to the standards around how to version the assemblies. The first thing I’ll do is add a file called SolutionAssemblyVersionInfo.cs to the root of my solution that looks like this: 1: using System; 2: using System.Reflection; 3: [assembly: AssemblyVersion("1.1.0.0")] 4: [assembly: AssemblyFileVersion("1.1.0.0")] I’ll then add that file as a Visual Studio link file to each project in my solution by right-clicking the project, “Add – Existing Item…” then when I click the SolutionAssemblyVersionInfo.cs file, making sure I “Add As Link”: Now the Solution Explorer will show our file. We can see that it’s a “link” file because of the black arrow in the icon within all our projects. Of course you’ll need to remove the AssemblyVersion and AssemblyFileVersion attributes from the AssemblyInfo.cs files to avoid the duplicate attributes since they now leave in the SolutionAssemblyVersionInfo.cs file. This is an extremely common technique so that all the projects in our solution can be versioned as a unit. At this point, we’re ready to write our custom activity. The primary consideration is that I want the developer and/or tech lead to be able to easily be in control of the Major.Minor and then I want the CI process to add the third number with a unique incremental number. We’ll leave the fourth position always “0” for now – it’s held in reserve in case the day ever comes where we need to do an emergency patch to Production based on a branched version.   Writing the Custom Workflow Activity Similar to Lamb’s post, I’m going to write two custom workflow activities. The “outer” activity (a xaml activity) will be pretty straight forward. It will check if the solution version file exists in the solution root and, if so, delegate the replacement of version to the AssemblyVersionInfo activity which is a CodeActivity highlighted in red below:   Notice that the arguments of this activity are the “solutionVersionFile” and “tfsBuildNumber” which will be passed in. The tfsBuildNumber passed in will look something like this: “CI_MyApplication.4” and we’ll need to grab the “4” (i.e., the incremental revision number) and put that in the third position. Then we’ll need to honor whatever was specified for Major.Minor in the SolutionAssemblyVersionInfo.cs file. For example, if the SolutionAssemblyVersionInfo.cs file had “1.1.0.0” for the AssemblyVersion (as shown in the first code block near the beginning of this post), then we want to resulting file to have “1.1.4.0”. Before we do anything, let’s put together a unit test for all this so we can know if we get it right: 1: [TestMethod] 2: public void Assembly_version_should_be_parsed_correctly_from_build_name() 3: { 4: // arrange 5: const string versionFile = "SolutionAssemblyVersionInfo.cs"; 6: WriteTestVersionFile(versionFile); 7: var activity = new VersionAssemblies(); 8: var arguments = new Dictionary<string, object> { 9: { "tfsBuildNumber", "CI_MyApplication.4"}, 10: { "solutionVersionFile", versionFile} 11: }; 12:   13: // act 14: var result = WorkflowInvoker.Invoke(activity, arguments); 15:   16: // assert 17: Assert.AreEqual("1.2.4.0", (string)result["newAssemblyFileVersion"]); 18: var lines = File.ReadAllLines(versionFile); 19: Assert.IsTrue(lines.Contains("[assembly: AssemblyVersion(\"1.2.0.0\")]")); 20: Assert.IsTrue(lines.Contains("[assembly: AssemblyFileVersion(\"1.2.4.0\")]")); 21: } 22: 23: private void WriteTestVersionFile(string versionFile) 24: { 25: var fileContents = "using System.Reflection;\n" + 26: "[assembly: AssemblyVersion(\"1.2.0.0\")]\n" + 27: "[assembly: AssemblyFileVersion(\"1.2.0.0\")]"; 28: File.WriteAllText(versionFile, fileContents); 29: }   At this point, the code for our AssemblyVersion activity is pretty straight forward: 1: [BuildActivity(HostEnvironmentOption.Agent)] 2: public class AssemblyVersionInfo : CodeActivity 3: { 4: [RequiredArgument] 5: public InArgument<string> FileName { get; set; } 6:   7: [RequiredArgument] 8: public InArgument<string> TfsBuildNumber { get; set; } 9:   10: public OutArgument<string> NewAssemblyFileVersion { get; set; } 11:   12: protected override void Execute(CodeActivityContext context) 13: { 14: var solutionVersionFile = this.FileName.Get(context); 15: 16: // Ensure that the file is writeable 17: var fileAttributes = File.GetAttributes(solutionVersionFile); 18: File.SetAttributes(solutionVersionFile, fileAttributes & ~FileAttributes.ReadOnly); 19:   20: // Prepare assembly versions 21: var majorMinor = GetAssemblyMajorMinorVersionBasedOnExisting(solutionVersionFile); 22: var newBuildNumber = GetNewBuildNumber(this.TfsBuildNumber.Get(context)); 23: var newAssemblyVersion = string.Format("{0}.{1}.0.0", majorMinor.Item1, majorMinor.Item2); 24: var newAssemblyFileVersion = string.Format("{0}.{1}.{2}.0", majorMinor.Item1, majorMinor.Item2, newBuildNumber); 25: this.NewAssemblyFileVersion.Set(context, newAssemblyFileVersion); 26:   27: // Perform the actual replacement 28: var contents = this.GetFileContents(newAssemblyVersion, newAssemblyFileVersion); 29: File.WriteAllText(solutionVersionFile, contents); 30:   31: // Restore the file's original attributes 32: File.SetAttributes(solutionVersionFile, fileAttributes); 33: } 34:   35: #region Private Methods 36:   37: private string GetFileContents(string newAssemblyVersion, string newAssemblyFileVersion) 38: { 39: var cs = new StringBuilder(); 40: cs.AppendLine("using System.Reflection;"); 41: cs.AppendFormat("[assembly: AssemblyVersion(\"{0}\")]", newAssemblyVersion); 42: cs.AppendLine(); 43: cs.AppendFormat("[assembly: AssemblyFileVersion(\"{0}\")]", newAssemblyFileVersion); 44: return cs.ToString(); 45: } 46:   47: private Tuple<string, string> GetAssemblyMajorMinorVersionBasedOnExisting(string filePath) 48: { 49: var lines = File.ReadAllLines(filePath); 50: var versionLine = lines.Where(x => x.Contains("AssemblyVersion")).FirstOrDefault(); 51:   52: if (versionLine == null) 53: { 54: throw new InvalidOperationException("File does not contain [assembly: AssemblyVersion] attribute"); 55: } 56:   57: return ExtractMajorMinor(versionLine); 58: } 59:   60: private static Tuple<string, string> ExtractMajorMinor(string versionLine) 61: { 62: var firstQuote = versionLine.IndexOf('"') + 1; 63: var secondQuote = versionLine.IndexOf('"', firstQuote); 64: var version = versionLine.Substring(firstQuote, secondQuote - firstQuote); 65: var versionParts = version.Split('.'); 66: return new Tuple<string, string>(versionParts[0], versionParts[1]); 67: } 68:   69: private string GetNewBuildNumber(string buildName) 70: { 71: return buildName.Substring(buildName.LastIndexOf(".") + 1); 72: } 73:   74: #endregion 75: }   At this point the final step is to incorporate this activity into the overall build template. Make a copy of the DefaultTempate.xaml – we’ll call it DefaultTemplateWithVersioning.xaml. Before the build and labeling happens, drag the VersionAssemblies activity in. Then set the LabelName variable to “BuildDetail.BuildDefinition.Name + "-" + newAssemblyFileVersion since the newAssemblyFileVersion was produced by our activity.   Configuring CI Once you add your solution to source control, you can configure CI with the build definition window as shown here. The main difference is that we’ll change the Process tab to reflect a different build number format and choose our custom build process file:   When the build completes, we’ll see the name of our project with the unique revision number:   If we look at the detailed build log for the latest build, we’ll see the label being created with our custom task:     We can now look at the history labels in TFS and see the project name with the labels (the Assignment activity I added to the workflow):   Finally, if we look at the physical assemblies that are produced, we can right-click on any assembly in Windows Explorer and see the assembly version in its properties:   Full Traceability We now have full traceability for our code. There will never be a question of what code was deployed to Production. You can always see the assembly version in the properties of the physical assembly. That can be traced back to a label in TFS where the unique revision number matches. The label in TFS gives you the complete snapshot of the code in your source control repository at the time the code was built. This type of process for full traceability has been used for many years for CI – in fact, I’ve done similar things with CCNet and SVN for quite some time. This is simply the TFS implementation of that pattern. The new features that TFS 2010 give you to make these types of customizations in your build process are quite easy once you get over the initial curve.

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• WPF ListView as a DataGrid – Part 2

  - by psheriff

  In my last blog post I showed you how to create GridViewColumn objects on the fly from the meta-data in a DataTable. By doing this you can create columns for a ListView at runtime instead of having to pre-define each ListView for each different DataTable. Well, many of us use collections of our classes and it would be nice to be able to do the same thing for our collection classes as well. This blog post will show you one approach for using collection classes as the source of the data for your ListView.  Figure 1: A List of Data using a ListView Load Property NamesYou could use reflection to gather the property names in your class, however there are two things wrong with this approach. First, reflection is too slow, and second you may not want to display all your properties from your class in the ListView. Instead of reflection you could just create your own custom collection class of PropertyHeader objects. Each PropertyHeader object will contain a property name and a header text value at a minimum. You could add a width property if you wanted as well. All you need to do is to create a collection of property header objects where each object represents one column in your ListView. Below is a simple example: PropertyHeaders coll = new PropertyHeaders(); coll.Add(new PropertyHeader("ProductId", "Product ID"));coll.Add(new PropertyHeader("ProductName", "Product Name"));coll.Add(new PropertyHeader("Price", "Price")); Once you have this collection created, you could pass this collection to a method that would create the GridViewColumn objects based on the information in this collection. Below is the full code for the PropertyHeader class. Besides the PropertyName and Header properties, there is a constructor that will allow you to set both properties when the object is created. C#public class PropertyHeader{  public PropertyHeader()  {  }   public PropertyHeader(string propertyName, string headerText)  {    PropertyName = propertyName;    HeaderText = headerText;  }   public string PropertyName { get; set; }  public string HeaderText { get; set; }} VB.NETPublic Class PropertyHeader  Public Sub New()  End Sub   Public Sub New(ByVal propName As String, ByVal header As String)    PropertyName = propName    HeaderText = header  End Sub   Private mPropertyName As String  Private mHeaderText As String   Public Property PropertyName() As String    Get      Return mPropertyName    End Get    Set(ByVal value As String)      mPropertyName = value    End Set  End Property   Public Property HeaderText() As String    Get      Return mHeaderText    End Get    Set(ByVal value As String)      mHeaderText = value    End Set  End PropertyEnd Class You can use a Generic List class to create a collection of PropertyHeader objects as shown in the following code. C#public class PropertyHeaders : List<PropertyHeader>{} VB.NETPublic Class PropertyHeaders  Inherits List(Of PropertyHeader)End Class Create Property Header Objects You need to create a method somewhere that will create and return a collection of PropertyHeader objects that will represent the columns you wish to add to your ListView prior to binding your collection class to that ListView. Below is a sample method called GetProperties that builds a list of PropertyHeader objects with properties and headers for a Product object. C#public PropertyHeaders GetProperties(){  PropertyHeaders coll = new PropertyHeaders();   coll.Add(new PropertyHeader("ProductId", "Product ID"));  coll.Add(new PropertyHeader("ProductName", "Product Name"));  coll.Add(new PropertyHeader("Price", "Price"));   return coll;} VB.NETPublic Function GetProperties() As PropertyHeaders  Dim coll As New PropertyHeaders()   coll.Add(New PropertyHeader("ProductId", "Product ID"))  coll.Add(New PropertyHeader("ProductName", "Product Name"))  coll.Add(New PropertyHeader("Price", "Price"))   Return collEnd Function WPFListViewCommon Class Now that you have a collection of PropertyHeader objects you need a method that will create a GridView and a collection of GridViewColumn objects based on this PropertyHeader collection. Below is a static/Shared method that you might put into a class called WPFListViewCommon. C#public static GridView CreateGridViewColumns(  PropertyHeaders properties){  GridView gv;  GridViewColumn gvc;   // Create the GridView  gv = new GridView();  gv.AllowsColumnReorder = true;   // Create the GridView Columns  foreach (PropertyHeader item in properties)  {    gvc = new GridViewColumn();    gvc.DisplayMemberBinding = new Binding(item.PropertyName);    gvc.Header = item.HeaderText;    gvc.Width = Double.NaN;    gv.Columns.Add(gvc);  }   return gv;} VB.NETPublic Shared Function CreateGridViewColumns( _    ByVal properties As PropertyHeaders) As GridView  Dim gv As GridView  Dim gvc As GridViewColumn   ' Create the GridView  gv = New GridView()  gv.AllowsColumnReorder = True   ' Create the GridView Columns  For Each item As PropertyHeader In properties    gvc = New GridViewColumn()    gvc.DisplayMemberBinding = New Binding(item.PropertyName)    gvc.Header = item.HeaderText    gvc.Width = [Double].NaN    gv.Columns.Add(gvc)  Next   Return gvEnd Function Build the Product Screen To build the window shown in Figure 1, you might write code like the following: C#private void CollectionSample(){  Product prod = new Product();   // Setup the GridView Columns  lstData.View = WPFListViewCommon.CreateGridViewColumns(       prod.GetProperties());  lstData.DataContext = prod.GetProducts();} VB.NETPrivate Sub CollectionSample()  Dim prod As New Product()   ' Setup the GridView Columns  lstData.View = WPFListViewCommon.CreateGridViewColumns( _       prod.GetProperties())  lstData.DataContext = prod.GetProducts()End Sub The Product class contains a method called GetProperties that returns a PropertyHeaders collection. You pass this collection to the WPFListViewCommon’s CreateGridViewColumns method and it will create a GridView for the ListView. When you then feed the DataContext property of the ListView the Product collection the appropriate columns have already been created and data bound. Summary In this blog you learned how to create a ListView that acts like a DataGrid using a collection class. While it does take a little code to do this, it is an alternative to creating each GridViewColumn in XAML. This gives you a lot of flexibility. You could even read in the property names and header text from an XML file for a truly configurable ListView. NOTE: You can download the complete sample code (in both VB and C#) at my website. http://www.pdsa.com/downloads. Choose Tips & Tricks, then "WPF ListView as a DataGrid – Part 2" from the drop-down. Good Luck with your Coding,Paul Sheriff ** SPECIAL OFFER FOR MY BLOG READERS **Visit http://www.pdsa.com/Event/Blog for a free eBook on "Fundamentals of N-Tier".  

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• Creating a Dynamic DataRow for easier DataRow Syntax

  - by Rick Strahl

  I've been thrown back into an older project that uses DataSets and DataRows as their entity storage model. I have several applications internally that I still maintain that run just fine (and I sometimes wonder if this wasn't easier than all this ORM crap we deal with with 'newer' improved technology today - but I disgress) but use this older code. For the most part DataSets/DataTables/DataRows are abstracted away in a pseudo entity model, but in some situations like queries DataTables and DataRows are still surfaced to the business layer. Here's an example. Here's a business object method that runs dynamic query and the code ends up looping over the result set using the ugly DataRow Array syntax:public int UpdateAllSafeTitles() { int result = this.Execute("select pk, title, safetitle from " + Tablename + " where EntryType=1", "TPks"); if (result < 0) return result; result = 0; foreach (DataRow row in this.DataSet.Tables["TPks"].Rows) { string title = row["title"] as string; string safeTitle = row["safeTitle"] as string; int pk = (int)row["pk"]; string newSafeTitle = this.GetSafeTitle(title); if (newSafeTitle != safeTitle) { this.ExecuteNonQuery("update " + this.Tablename + " set safeTitle=@safeTitle where pk=@pk", this.CreateParameter("@safeTitle",newSafeTitle), this.CreateParameter("@pk",pk) ); result++; } } return result; } The problem with looping over DataRow objecs is two fold: The array syntax is tedious to type and not real clear to look at, and explicit casting is required in order to do anything useful with the values. I've highlighted the place where this matters. Using the DynamicDataRow class I'll show in a minute this code can be changed to look like this:public int UpdateAllSafeTitles() { int result = this.Execute("select pk, title, safetitle from " + Tablename + " where EntryType=1", "TPks"); if (result < 0) return result; result = 0; foreach (DataRow row in this.DataSet.Tables["TPks"].Rows) { dynamic entry = new DynamicDataRow(row); string newSafeTitle = this.GetSafeTitle(entry.title); if (newSafeTitle != entry.safeTitle) { this.ExecuteNonQuery("update " + this.Tablename + " set safeTitle=@safeTitle where pk=@pk", this.CreateParameter("@safeTitle",newSafeTitle), this.CreateParameter("@pk",entry.pk) ); result++; } } return result; } The code looks much a bit more natural and describes what's happening a little nicer as well. Well, using the new dynamic features in .NET it's actually quite easy to implement the DynamicDataRow class. Creating your own custom Dynamic Objects .NET 4.0 introduced the Dynamic Language Runtime (DLR) and opened up a whole bunch of new capabilities for .NET applications. The dynamic type is an easy way to avoid Reflection and directly access members of 'dynamic' or 'late bound' objects at runtime. There's a lot of very subtle but extremely useful stuff that dynamic does (especially for COM Interop scenearios) but in its simplest form it often allows you to do away with manual Reflection at runtime. In addition you can create DynamicObject implementations that can perform  custom interception of member accesses and so allow you to provide more natural access to more complex or awkward data structures like the DataRow that I use as an example here. Bascially you can subclass DynamicObject and then implement a few methods (TryGetMember, TrySetMember, TryInvokeMember) to provide the ability to return dynamic results from just about any data structure using simple property/method access. In the code above, I created a custom DynamicDataRow class which inherits from DynamicObject and implements only TryGetMember and TrySetMember. Here's what simple class looks like:/// <summary> /// This class provides an easy way to turn a DataRow /// into a Dynamic object that supports direct property /// access to the DataRow fields. /// /// The class also automatically fixes up DbNull values /// (null into .NET and DbNUll to DataRow) /// </summary> public class DynamicDataRow : DynamicObject { /// <summary> /// Instance of object passed in /// </summary> DataRow DataRow; /// <summary> /// Pass in a DataRow to work off /// </summary> /// <param name="instance"></param> public DynamicDataRow(DataRow dataRow) { DataRow = dataRow; } /// <summary> /// Returns a value from a DataRow items array. /// If the field doesn't exist null is returned. /// DbNull values are turned into .NET nulls. /// /// </summary> /// <param name="binder"></param> /// <param name="result"></param> /// <returns></returns> public override bool TryGetMember(GetMemberBinder binder, out object result) { result = null; try { result = DataRow[binder.Name]; if (result == DBNull.Value) result = null; return true; } catch { } result = null; return false; } /// <summary> /// Property setter implementation tries to retrieve value from instance /// first then into this object /// </summary> /// <param name="binder"></param> /// <param name="value"></param> /// <returns></returns> public override bool TrySetMember(SetMemberBinder binder, object value) { try { if (value == null) value = DBNull.Value; DataRow[binder.Name] = value; return true; } catch {} return false; } } To demonstrate the basic features here's a short test: [TestMethod] [ExpectedException(typeof(RuntimeBinderException))] public void BasicDataRowTests() { DataTable table = new DataTable("table"); table.Columns.Add( new DataColumn() { ColumnName = "Name", DataType=typeof(string) }); table.Columns.Add( new DataColumn() { ColumnName = "Entered", DataType=typeof(DateTime) }); table.Columns.Add(new DataColumn() { ColumnName = "NullValue", DataType = typeof(string) }); DataRow row = table.NewRow(); DateTime now = DateTime.Now; row["Name"] = "Rick"; row["Entered"] = now; row["NullValue"] = null; // converted in DbNull dynamic drow = new DynamicDataRow(row); string name = drow.Name; DateTime entered = drow.Entered; string nulled = drow.NullValue; Assert.AreEqual(name, "Rick"); Assert.AreEqual(entered,now); Assert.IsNull(nulled); // this should throw a RuntimeBinderException Assert.AreEqual(entered,drow.enteredd); } The DynamicDataRow requires a custom constructor that accepts a single parameter that sets the DataRow. Once that's done you can access property values that match the field names. Note that types are automatically converted - no type casting is needed in the code you write. The class also automatically converts DbNulls to regular nulls and vice versa which is something that makes it much easier to deal with data returned from a database. What's cool here isn't so much the functionality - even if I'd prefer to leave DataRow behind ASAP -  but the fact that we can create a dynamic type that uses a DataRow as it's 'DataSource' to serve member values. It's pretty useful feature if you think about it, especially given how little code it takes to implement. By implementing these two simple methods we get to provide two features I was complaining about at the beginning that are missing from the DataRow: Direct Property Syntax Automatic Type Casting so no explicit casts are required Caveats As cool and easy as this functionality is, it's important to understand that it doesn't come for free. The dynamic features in .NET are - well - dynamic. Which means they are essentially evaluated at runtime (late bound). Rather than static typing where everything is compiled and linked by the compiler/linker, member invokations are looked up at runtime and essentially call into your custom code. There's some overhead in this. Direct invocations - the original code I showed - is going to be faster than the equivalent dynamic code. However, in the above code the difference of running the dynamic code and the original data access code was very minor. The loop running over 1500 result records took on average 13ms with the original code and 14ms with the dynamic code. Not exactly a serious performance bottleneck. One thing to remember is that Microsoft optimized the DLR code significantly so that repeated calls to the same operations are routed very efficiently which actually makes for very fast evaluation. The bottom line for performance with dynamic code is: Make sure you test and profile your code if you think that there might be a performance issue. However, in my experience with dynamic types so far performance is pretty good for repeated operations (ie. in loops). While usually a little slower the perf hit is a lot less typically than equivalent Reflection work. Although the code in the second example looks like standard object syntax, dynamic is not static code. It's evaluated at runtime and so there's no type recognition until runtime. This means no Intellisense at development time, and any invalid references that call into 'properties' (ie. fields in the DataRow) that don't exist still cause runtime errors. So in the case of the data row you still get a runtime error if you mistype a column name:// this should throw a RuntimeBinderException Assert.AreEqual(entered,drow.enteredd); Dynamic - Lots of uses The arrival of Dynamic types in .NET has been met with mixed emotions. Die hard .NET developers decry dynamic types as an abomination to the language. After all what dynamic accomplishes goes against all that a static language is supposed to provide. On the other hand there are clearly scenarios when dynamic can make life much easier (COM Interop being one place). Think of the possibilities. What other data structures would you like to expose to a simple property interface rather than some sort of collection or dictionary? And beyond what I showed here you can also implement 'Method missing' behavior on objects with InvokeMember which essentially allows you to create dynamic methods. It's all very flexible and maybe just as important: It's easy to do. There's a lot of power hidden in this seemingly simple interface. Your move…© Rick Strahl, West Wind Technologies, 2005-2011Posted in CSharp  .NET   Tweet (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• Can static methods be called using object/instance in .NET

  Ans is Yes and No   Yes in C++, Java and VB.NET No in C#   This is only compiler restriction in c#. You might see in some websites that we can break this restriction using reflection and delegates, but we can’t, according to my little research J I shall try to explain you…   Following is code sample to break this rule using reflection, it seems that it is possible to call a static method using an object, p1 using System; namespace T {     class Program     {         static void Main()         {             var p1 = new Person() { Name = "Smith" };             typeof(Person).GetMethod("TestStatMethod").Invoke(p1, new object[] { });                     }         class Person         {             public string Name { get; set; }             public static void TestStatMethod()             {                 Console.WriteLine("Hello");             }         }     } } but I do not think so this method is being called using p1 rather Type Name “Person”. I shall try to prove this… look at another example…  Test2 has been inherited from Test1. Let’s see various scenarios… Scenario1 using System; namespace T {     class Program     {         static void Main()         {             Test1 t = new Test1();            typeof(Test2).GetMethod("Method1").Invoke(t,                                  new object[] { });         }     }     class Test1     {         public static void Method1()         {             Console.WriteLine("At test1::Method1");         }     }       class Test2 : Test1     {         public static void Method1()         {             Console.WriteLine("At test1::Method2");         }     } } Output:   At test1::Method2 Scenario2         static void Main()         {             Test2 t = new Test2();            typeof(Test2).GetMethod("Method1").Invoke(t,                                          new object[] { });         }   Output:   At test1::Method2   Scenario3         static void Main()         {             Test1 t = new Test2();            typeof(Test2).GetMethod("Method1").Invoke(t,                             new object[] { });         }   Output: At test1::Method2 In all above scenarios output is same, that means, Reflection also not considering the object what you pass to Invoke method in case of static methods. It is always considering the type which you specify in typeof(). So, what is the use passing instance to “Invoke”. Let see below sample using System; namespace T {     class Program     {         static void Main()         {            typeof(Test2).GetMethod("Method1").                Invoke(null, new object[] { });         }     }       class Test1     {         public static void Method1()         {             Console.WriteLine("At test1::Method1");         }     }     class Test2 : Test1     {         public static void Method1()         {             Console.WriteLine("At test1::Method2");         }     } }   Output is   At test1::Method2   I was able to call Invoke “Method1” of Test2 without any object.  Yes, there no wonder here as Method1 is static. So we may conclude that static methods cannot be called using instances (only in c#) Why Microsoft has restricted it in C#? Ans: Really there Is no use calling static methods using objects because static methods are stateless. but still Java and C++ latest compilers allow calling static methods using instances. Java sample class Test {      public static void main(String str[])      {            Person p = new Person();            System.out.println(p.GetCount());      } }   class Person {   public static int GetCount()   {      return 100;   } }   Output          100 span.fullpost {display:none;}

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• Windows 7 Complete PC Backup - Fails with error code: 0x80070002

  - by leeand00

  While doing a Complete PC Backup in Windows 7 I received dialog reading: Windows Backup...error The backup did not complete successfully. Open the Backup and Restore Control Panel to view settings From there I clicked the Options button. Windows Backup: Troubleshooting Options Check your backup Windows Backup encountered invalid MediaID.bin file on the drive where the backup is saved. Restore from a different backup or delete the MediaID.bin file and try to create another backup. The MediaID.bin file can be found under \MediaID.Bin & \\MediaId.Bin. I deleted the file in question (MediaID.bin) from X:\ (one of the drives being backedup( and tried the backup again. Next I was presented with a dialog that read: Windows Backups: Troubleshooting Options Check your backup The system connot find the file specified. Try to run backup again Change backup settings Backup Time: 2/10/2010 12:17 PM Backup location: FreeAgent Drive (E:) Error code: 0x80070002 Additionally I checked the error log and I found this: <Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event"> <System> <Provider Name="Windows Backup" /> <EventID Qualifiers="0">4104</EventID> <Level>2</Level> <Task>0</Task> <Keywords>0x80000000000000</Keywords> <TimeCreated SystemTime="2010-02-10T17:17:48.000000000Z" /> <EventRecordID>5107</EventRecordID> <Channel>Application</Channel> <Computer>leeand00-PC</Computer> <Security /> </System> - <EventData> <Data>The system cannot find the file specified. (0x80070002)</Data> <Binary>02000780E30500003F0900005B090000420ED1665C2BEE174B64529CB14610EA71000000</Binary> </EventData> </Event> Viewed the following document: http://blogs.technet.com/filecab/archive/2008/03/12/common-causes-and-solutions-to-backup-system-restore-and-complete-pc-backup-problems-updated.aspx searched for 0x80070002 and tried and follow the directions... I noticed that none of the profiles was missing a ProfileImagePath, I also noticed that the people commenting on the page said that they weren't missing it either. I'm currently trying the backup again, but this time I unchecked all of the user's profiles and opted only to backup the two drives X: and C: on to E:\ I'll let you know what happens. Any ideas?

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• Error codes 80070490 and 8024200D in Windows Update

  - by Sammy

  How do get past these stupid errors? The way I have set things up is that Windows Update tells me when there are new updates available and then I review them before installing them. Yesterday it told me that there were 11 new updates. So I reviewed them and I saw that about half of them were security updates for Vista x64 and .NET Framework 2.0 SP2, and half of them were just regular updates for Vista x64. I checked them all and hit the Install button. It seemed to work at first, updates were being downloaded and installed, but then at update 11 of 11 total it got stuck and gave me the two error codes you see in the title. Here are some screenshots to give you an idea of what it looks like. This is what it looks like when it presents the updates to me. This is how it looks like when the installation fails. I'm not sure if you're gonna see this very well but these are the updates it's trying to install. Update: This is on Windows Vista Ultimate 64-bit with integrated SP2, installed only two weeks ago on 2012-10-02. Aside from this, the install is working flawlessly. I have not done any major changes to the system like installing new devices or drivers. What I have tried so far: - I tried installing the System Update Readiness Tool (the correct one for Vista x64) from Microsoft. This did not solve the issue. Microsoft resource links: Solutions to 80070490 Windows Update error 80070490 System Update Readiness Tool fixes Windows Update errors in Windows 7, Windows Vista, Windows Server 2008 R2, and Windows Server 2008 Solutions to 8024200D: Windows Update error 8024200d Essentially both solutions tell you to install the System Update Readiness Tool for your system. As I have done so and it didn't solve the problem the next step would be to try to repair Windows. Before I do that, is there anything else I can try? Microsoft automatic troubleshooter If I click the automatic troubleshooter link available on the solution web page above it directs me to download a file called windowsupdate.diagcab. But after download this file is not associated to any Windows program. Is this the so called Microsoft Fix It program? It doesn't have its icon, it's just blank file. Does it need to be associated? And to what Windows program?

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• Python error after installing libboost-all-dev on debian [migrated]

  - by Cameron Metzke

  A friend of mine wanted the liboost libraries installed on our shared computer so after installing libboost-all-dev 1.49.0.1 ( A debian wheezy machine ), I get this error when using the "pydoc modules" command on the commandline. It spits out the following error -- root@debian:/usr/include/c++/4.7# pydoc modules Please wait a moment while I gather a list of all available modules... **[debian:49065] [[INVALID],INVALID] ORTE_ERROR_LOG: A system-required executable either could not be found or was not executable by this user in file ../../../../../../orte/mca/ess/singleton/ess_singleton_module.c at line 357 [debian:49065] [[INVALID],INVALID] ORTE_ERROR_LOG: A system-required executable either could not be found or was not executable by this user in file ../../../../../../orte/mca/ess/singleton/ess_singleton_module.c at line 230 [debian:49065] [[INVALID],INVALID] ORTE_ERROR_LOG: A system-required executable either could not be found or was not executable by this user in file ../../../orte/runtime/orte_init.c at line 132 -------------------------------------------------------------------------- It looks like orte_init failed for some reason; your parallel process is likely to abort. There are many reasons that a parallel process can fail during orte_init; some of which are due to configuration or environment problems. This failure appears to be an internal failure; here's some additional information (which may only be relevant to an Open MPI developer): orte_ess_set_name failed --> Returned value A system-required executable either could not be found or was not executable by this user (-127) instead of ORTE_SUCCESS -------------------------------------------------------------------------- -------------------------------------------------------------------------- It looks like MPI_INIT failed for some reason; your parallel process is likely to abort. There are many reasons that a parallel process can fail during MPI_INIT; some of which are due to configuration or environment problems. This failure appears to be an internal failure; here's some additional information (which may only be relevant to an Open MPI developer): ompi_mpi_init: orte_init failed --> Returned "A system-required executable either could not be found or was not executable by this user" (-127) instead of "Success" (0) -------------------------------------------------------------------------- *** The MPI_Init() function was called before MPI_INIT was invoked. *** This is disallowed by the MPI standard. *** Your MPI job will now abort. [debian:49065] Abort before MPI_INIT completed successfully; not able to guarantee that all other processes were killed!** root@debian:/usr/include/c++/4.7# I tried looking into the problem and ended up uninstalling the following to get it to work again. openmpi common all 1.4.5-1 libibverbs-dev amd64 1.1.6-1 libopenmpi-dev amd64 1.4.5-1 mpi-default-dev amd64 1.0.1 libboost-mpi-python1.49.0 although pydoc works again, I'm assuming the packages I removed are gunna hurt somethiong else down the track ? As you guessed im not a c/c++ programmer. So I guess my question is, will this hurt something later ? is their a way to install those packages without hurting python ?

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• Weird random application hang problem

  - by haridsv

  I am trying to understand an application hang problem that started up lately on my windows xp system. The system runs fine for days (sometimes) without ever shutting down or putting it to sleep, but the problem first shows up as one of the apps hanging. The application's UI stops responding or one or more background threads hang, so even though the GUI is responding, it is not doing anything (e.g., in VirtualDub's case, the UI responds fine, but the job doesn't progress and I won't even be able to abort it). The weirdness part comes from the fact that if I try to kill such an app, the program that is used to kill it goes into the same mode (i.e, that hangs instead of the original). E.g., if I use Process Explorer to kill it, the original program exits, but procexp now hangs. If I use another instance of procexp to kill the one that is hanging, this repeats, so there is always at least one program hanging in that state. This is not specific to procexp, I tried the native task manager and even the "End Process" dialog from windows explorer that shows up when you try to close a non-responsive GUI (in this case, the explorer itself hangs). The only program that didn't hang after the kill, is the command line taskkill. However, in this case, explorer hangs instead of taskkill. Also, once this problem starts manifesting, it soon ends up freezing the whole system to the extent that even a clean shutdown is not possible, so I have learned to reboot as soon as I notice this problem, however this is very inconvenient, as I often have encoding batch jobs going on which can't continue the job after the restart. The longer I leave the system running after seeing this problem, the more applications get into this state. I have tried to do a repair install but that didn't make any difference. I also uninstalled some of the newer installs, but again no difference. I tried to search online, but got inundating results for generic hang and crash related problems. Though I couldn't notice any pattern, it seems as though the problem is more frequent if I have some video encoding going on at that time. I had the system running for days when I only do browsing and internet audio/video chat before I decide to start encoding something and the problem starts to show up. I am not too sure if it is the encoding program that first hangs, though I almost always noticed that too hanging (like the VirtualDub stopping to make progress). I also had to reboot 3 times on one day when I was heavily experimenting with encoding. I would appreciate any help in narrowing down this problem and save me the trouble of reinstalling. I don't especially want to loose my gotd installs.

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• Windows Server 2008 R2 time keeps changing unexpectedly

  - by lmhost

  There is a serious problem with one of my servers time. At some random hours (5:59 localtime in the following example) it goes 1 hour back and keeps doing this again and again next times it reaches 5:59. Like this: 5:59-4:59 … 5:59- 4:59 and so on. It stays in the loop until I manually update its time. The server OS is Windows 2008 R2 Standard x64, acting as a standalone web server on the internet. time zone (UTC-05:00). system log: Information 4/13/2012 5:59:34 PM Kernel-General 1 None Information 4/13/2012 5:59:34 PM Kernel-General 1 None Information 4/13/2012 5:59:34 PM Kernel-General 1 None Information 4/13/2012 5:59:34 PM Kernel-General 1 None Information 4/13/2012 5:59:34 PM Kernel-General 1 None Information 4/13/2012 5:59:34 PM Kernel-General 1 None all of the above entries have same content: The system time has changed to ?2012?-?04?-?13T21:59:34.500000000Z from ?2012?-?04?-?13T22:59:34.500000000Z. Details XML View: - <Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event"> - <System> <Provider Name="Microsoft-Windows-Kernel-General" Guid="{A68CA8B7-004F-D7B6-A698-07E2DE0F1F5D}" /> <EventID>1</EventID> <Version>0</Version> <Level>4</Level> <Task>0</Task> <Opcode>0</Opcode> <Keywords>0x8000000000000010</Keywords> <TimeCreated SystemTime="2012-04-13T21:59:34.500000000Z" /> <EventRecordID>4060</EventRecordID> <Correlation /> <Execution ProcessID="4" ThreadID="80" /> <Channel>System</Channel> <Computer>********</Computer> <Security UserID="S-1-5-18" /> </System> - <EventData> <Data Name="NewTime">2012-04-13T21:59:34.500000000Z</Data> <Data Name="OldTime">2012-04-13T22:59:34.500000000Z</Data> </EventData> </Event> Any idea about what’s going on? Thanks

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• Windows 7 The boot selection failed because a required device is inaccessible 0xc000000f

  - by piratejackus

  I have a problem with my Windows 7, hardware : Acer 3820TG Operating Systems : Windows 7 and Ubuntu 10.04 dual Case: When I try to boot my windows 7 I see an error: "Window failed to start. A recent hardware or software change might be the cause. To fix the problem: 1.Insert.... 2. .... ... status : 0xc000000f info : The boot selection failed because a required device is inaccessible .... " I can't exactly remember what were my last actions on Windows. I already searched this error and applied the proposed solutions, I created a repair USB (because I don't have a CD-ROM nor a Windows 7 CD) such as; -repair operating system :it says it cannot repair it -checking disk (chkdsk D: /f /r) : it checks the disk without a problem or error and it takes pretty long (more than a hour). But when I restart, still the same error. -I didn't create a restore point so I pass this option -I don't have a system image -I tried to run windows recovery (I have a recovery partition) but there are just two options: 1- Format the operating system but retain user data (copies the files under users to c\backup folder, but when I searched deeper I found that there are some people who already tried this option and couldn't find their user files under backup directory). Plus, I have unfortunately just one partition D (it is a fault I know) because I use always Ubuntu. So this is not applicable in my situation 2- Format entire system (Windows). I keep my valuable data in windows but not in user folder. I was reaching them from Windows. -I tried to repair windows boot by: bootrec /fixMBR bootrec /fixBoot bootrec /rebuildBCD I lost all grub menu, and reinstalled it. - ubuntuforums.org/showthread.php?t=1014708&page=29 nothing changed, same error. I created a thread in microsoft forums - http://social.answers.microsoft.com/Forums/en-US/w7install/thread/69517faf-850a-45fd- 8195-6d4ed831f805 but I couldn't find a solution. Before I run chkdsk from usb repair disk I couldn't able to mount Windows (NTFS) partition from Ubuntu, I was getting "couldn't mount file system, error code 2". I tried to fix ntfs partition from ubuntu and got "segmentation fault". I also created a thread on ubuntuforums for this mount problem: - http://ubuntuforums.org/showthread.php?t=1606427 So, after chkdsk, I could enable to mount windows partition but all I see in this partition is chkdsk logs, no any other data. Now, I don't think I lost my data because I don't get any filesystem errors, just the boot section, but this log files under windows partition makes me afraid. I see that Microsoft developers don't have a solution yet for this error. If you need any information to get more idea I can give, maybe I miss some points or it could be complicated. Thanks in advance.

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• Areca 1280ml RAID6 volume set failed

  - by Richard

  Today we hit some kind of worst case scenario and are open to any kind of good ideas. Here is our problem: We are using several dedicated storage servers to host our virtual machines. Before I continue, here are the specs: Dedicated Server Machine Areca 1280ml RAID controller, Firmware 1.49 12x Samsung 1TB HDDs We configured one RAID6-set with 10 discs that contains one logical volume. We have two hot spares in the system. Today one HDD failed. This happens from time to time, so we replaced it. Upon rebuilding a second disc failed. Normally this is no fun. We stopped heavy IO-operations to ensure a stable RAID rebuild. Sadly the hot-spare disc failed while rebuilding and the whole thing stopped. Now we have the following situation: The controller says that the raid set is rebuilding The controller says that the volume failed It is a RAID 6 system and two discs failed, so the data has to be intact, but we cannot bring the volume online again to access the data. While searching we found the following leads. I don't know whether they are good or bad: Mirroring all the discs to a second set of drives. So we would have the possibility to try different things without loosing more than we already have. Trying to rebuild the array in R-Studio. But we have no real experience with the software. Pulling all drives, rebooting the system, changing into the areca controller bios, reinserting the HDDs one-by-one. Some people are saying that the brought the system online by this. Some are saying that the effect is zero. Some say, that they blew the whole thing. Using undocumented areca commands like "rescue" or "LeVel2ReScUe". Contacting a computer forensics service. But whoa... primary estimates by phone exceeded 20.000€. That's why we would kindly ask for help. Maybe we are missing the obvious? And yes of course, we have backups. But some systems lost one week of data, thats why we'd like to get the system up and running again. Any help, suggestions and questions are more than welcome.

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• Why is my new Phenom II 965 BE not significantly faster than my old Athlon 64 X2 4600+?

  - by Software Monkey

  I recently rebuilt my 5 year old computer. I upgraded all core components, in particular from an Athlon 64 X2 4600+ at 2.4 GHz with DDR2 800 to a Phenom II 965 BE (quad core) at 3.6 GHz with DDR3 1333 (actually 1600, but testing consistently detected memory errors at 1600). The motherboard is also much newer and better. The HDD's (x3), DVD writer and card reader are the same. The BIOS memory config is auto-everything except the base timing which I overrode to 1T instead of 2T. The BIOS CPU multiplier is slightly over-clocked to 3.6 GHz from the stock 3.4 GHz. I noticed compiling Java is slower than I expected. As it happens I have some (single-threaded) Java pattern-matching code which is CPU and memory bound and for which I have performance numbers recorded on a number of hardware platforms, including my old system. So I did a test run on the new equipment and was stunned to find that the numbers are only slightly better than my old system, about 25%. The data set it is operating on is a 148,975 character array, which should easily fit in caches, but in any event the new CPU has larger caches all around. The system was, of course, otherwise idle for the test and the test run is a timed 10 seconds to eliminate scheduling anomalies. A long while ago, when I upgraded only memory from DD2 667 to DDR2 800 there was no change in performance of this test, which subjectively supports that the test cycle does not need to (significantly) access main memory, but yes it is creating and garbage collecting a large number of objects in the process of this test (low millions of matches are found for the pattern set). I am about 99.999% certain the code hasn't changed since I last ran it on 2009-03-17 - but I can't easily retest the old hardware, because it is currently in pieces on my work-bench waiting to be built into a new computer for my kids. Note that Windows (XP) reports a CPU speed of 795 MHz unless I have some thing running. With stuff running it seems to jump all over the place each time I use ALT-Pause to display the system properties, everywhere from 795 MHz to 3.4 Ghz. So why might my shiny new hardware under-performing so badly? EDIT: The old memory was Mushkin DDR2 800 with timings set for auto which should have been 5-5-5-12. The new memory is Corsair DDR3 1600, running at 1333 with timings also auto which are 9-9-9-21. In both cases they are a paired set of dual channel DIMMs. I was waiting to ensure my system was stable before tweaking with memory timings.

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• Wake On Lan only works on first boot, not sequent ones

  - by sp3ctum

  I have converted my old Dell Latitude D410 laptop to a server for tinkering. It is running an updated Debian Squeeze (6) with a Xen enabled kernel (I want to toy with virtual machines later on). I am running it 'headless' via an ethernet connection. I am struggling to enable Wake On Lan for the box. I have enabled the setting in the BIOS, and it works nicely, but only for the first time after the power cord is plugged in. Here is my test: Plug in power cord, don't boot yet Send magic Wake On Lan packet from test machine (Ubuntu) using the wakeonlan program Server expected to start (does every time) Once server has booted, log in via ssh and shut it down via the operating system After shutdown, wake server up via WOL again (fails every time) Some observations: Right after step 1 I can see the integrated NIC has a light on. I deduce this means the NIC gets adequate power and that the ethernet cable is connected to my switch. This light is not on after step 4 (the shutdown stage). The light becomes back on after I disconnect and reconnect the power cord, after which WOL works as well. After step 4 I can verify that wake on lan is enabled via the ethtool program (repeatable each time) This blog post suggested the problem may lay in the fact the motherboard might not be giving adequate power to the NIC after shutdown, so I copied an acpitool script that supposedly should signal the system to give the needed power to the card when shut down. Obviously it did not fix my issue. I have included the relevant power settings in the paste below. I have tried different combinations of parameters of shutdown (the program) options, as well as the poweroff program. I even tried "telinit 0", which I figured would do the most direct boot via software. If I keep the laptop's power button pressed down and do a hard boot this way, the light on the ethernet port stays lit and a WOL is possible. I copied a bunch of hopefully useful information in this paste I have tried this with the laptop battery connected and without it. I get the same result. Promptly pressing the power button causes the system to shut down with the message "The system is going down for system halt NOW!", and WOL is still unsuccessful.

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• HP UX can not boot from Ignite Tape

  - by Spirit

  We have hp rp2470 server running hp-ux 11.00, with LVM mirroring. As for redundancy we have second rp2470 same hw (same two processors, same ram, same two hdd’s, same number of lan cards). I want to clone first one to the second. For that purpose I am making ignite tape with the following command: make_tape_recovery -x inc_entire=vg00 Ignite tape finishes without problems. When I boot second server from this ignate tape, server is starting to boot, and ignite restore finishes without any errors, only few notes, which are normal. However vmunix is not booting and when restore finishes, it boot to ISL prompt. From this I cannot boot /stand/vmunix. I tried to run recovery shell but no success. When recovery shell ask to do frecover to restore critical files, then I receive error: frecover(5405): unable to open /dev/rmt/0m At first I thought that the problem might be in the difference of the firmware version of the servers: fw version of production server is: Firmware Version 43.50 and fw version of backup server is: Firmware Version 42.19 So i did a fw upgrade of my backup server so that both servers are v43.50, and tried a recovery but again cant boot the system. Next I did another archive tape with -I (Interactive) flag: make_tape_recovery -I -x inc_entire=vg00 and tried recovery with it, again no good. I cannot find any error or warnings on ignite log, and I cannot boot hpux. I am only on ISL prompt. This is what i've noticed on the gsp logs: ************* SYSTEM ALERT ************** SYSTEM NAME: mcnfwim1 DATE: 07/27/2003 TIME: 10:18:49 ALERT LEVEL: 6 = Boot possible, pending failure - action required REASON FOR ALERT SOURCE: 8 = I/O SOURCE DETAIL: 6 = disk SOURCE ID: 0 PROBLEM DETAIL: 0 = no problem detail LEDs: RUN ATTENTION FAULT REMOTE POWER FLASH OFF ON ON ON LED State: Boot Failed. Running non-OS code. Check Chassis and Console Logs for error messages. 0x00000060860010B0 00000000 00000000 - type 0 = Data Field Unused 0x58000860860010B0 00006706 1B0A1231 - type 11 = Timestamp 07/27/2003 10:18:49 And another gsp log: Log Entry # 3 : SYSTEM NAME: mcnfwim1 DATE: 07/27/2003 TIME: 10:12:20 ALERT LEVEL: 6 = Boot possible, pending failure - action required SOURCE: 8 = I/O SOURCE DETAIL: 6 = disk SOURCE ID: 0 PROBLEM DETAIL: 0 = no problem detail CALLER ACTIVITY: 1 = test STATUS: 0 CALLER SUBACTIVITY: 0B = implementation dependent REPORTING ENTITY TYPE: 0 = system firmware REPORTING ENTITY ID: 00 0x00000060860010B0 00000000 00000000 type 0 = Data Field Unused 0x58000860860010B0 00006706 1B0A0C14 type 11 = Timestamp 07/27/2003 10:12:20 Type CR for next entry, - CR for previous entry, Q CR to quit. Please note that I can not change anything on the production server. I can only make changes to the backup server. Any help is appreciated.

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• Server 2008 Likes to restart itself

  - by Campo

  I have a weird issue here. I notice about once a week the web server restarts itself. This would be only a minor issue if we were not planning on implementing an IP failover. I have checked the event logs. I don't see anything that indicates a reason for the restart. I need some help diagnosing the reason the server restarts. It happened last night at 5:00AM Last even in the log was 1 hour before the unexpected shutdown. Here is the Log for the shutdown event. Any help is much appreciated. I know there isn't much to go on yet. Log Name: System Source: EventLog Date: 5/5/2010 5:01:12 AM Event ID: 6008 Task Category: None Level: Error Keywords: Classic User: N/A Computer: SERVERNAME Description: The previous system shutdown at 4:56:41 AM on 5/5/2010 was unexpected. Event Xml: <Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event"> <System> <Provider Name="EventLog" /> <EventID Qualifiers="32768">6008</EventID> <Level>2</Level> <Task>0</Task> <Keywords>0x80000000000000</Keywords> <TimeCreated SystemTime="2010-05-05T09:01:12.000Z" /> <EventRecordID>346094</EventRecordID> <Channel>System</Channel> <Computer>SERVERNAME</Computer> <Security /> </System> <EventData> <Data>4:56:41 AM</Data> <Data>5/5/2010</Data> <Data> </Data> <Data> </Data> <Data>39594</Data> <Data> </Data> <Data> </Data> <Binary>DA070500030005000400380029008E03DA070500030005000800380029008E033C0000003C000000000 000000000000000000000000000000100000000000000</Binary> </EventData> </Event>

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• Should use EXT4 or XFS to be able to 'sync'/backup to S3?

  - by Rafa

  It's my first message here, so bear with me... (I have already checked quite a few of the "Related Questions" suggested by the editor) Here's the setup, a brand new dedicated server (8GB RAM, some 140+ GB disk, Raid 1 via HW controller, 15000 RPM) it's a production web server (with MySQL in it, too, not just serving web requests); not a personal desktop computer or similar. Ubuntu Server 64bit 10.04 LTS We have an Amazon EC2+EBS setup with the EBS volume formatted as XFS for easily taking snapshots to S3, via AWS' console. We are now migrating to the dedicated server and I want to be able to backup our data to Amazon's S3. The main reason being the possibility of using the latest snapshot from an EC2 instance in case of hardware failure on the dedicated server. There are two approaches I am thinking of: do a "simple" file-based backup with rsync, dumping the database' and other files, and uploading to amazon via S3 API commands, or to an EC2 instance, or something. do a file-system "freeze" (using XFS) with the usual ebs/ec2 snapshot tool to take part of the file system, take a snapshot, and upload it to Amazon. Here's my question (or series of questions): Can I safely use XFS for the whole system as the main and only format on the dedicated server? If not, is it safe to use EXT4? Or should I use something else? would then be possible to make snapshots of the system to upload to Amazon? Is it possible/feasible/practical to do what I want to do, anyway? any recommendations? When searching around for S3/EBS/XFS, anything relevant to my problem is usually focused on taking snapshots of a XFS system that is already an EBS volume. My intention is to do it in a "real"/metal dedicated server. Update: I just saw this on Wikipedia: XFS does not provide direct support for snapshots, as it expects the snapshot process to be implemented by the volume manager. I had always assumed that I could choose 2 ways of doing snapshots: via LVM or via XFS (without LVM). After reading this, I realize these 2 options are more like it: With XFS: 1) do xfs_freeze; 2) copy the frozen files via, eg, rsync; 3) unfreeze xfs With LVM and XFS: 1) do xfs_freeze; 2) make a binary copy of the frozen fs via lvcreate and related commands; 3) unfreeze xfs; 4) somehow backup the LVM snapshot. Thanks a lot in advance, Let me know if I need to clarify something.

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• Network Services disabled (not starting) on Windows XP

  - by Rickesh John

  I am currently running Windows XP Service Pack 3 on my system. But today, when I failed to connect to the internet, via a LAN cable, I realized that almost all of the vital network services had stopped functioning. Any attempts to start it through services.msc gives me the following message: Could not start the DNS Client Service on Local Computer Error 1068: The dependency service group failed to start All my software or services that are related to networking have stopped functioning, for example, Windows Firewall is turned off permanently, so is my Avast Anti-Virus' service of Real Time Shields and Web Shield. When I insert the LAN wire into my laptop, it registers itself, but this is what I get when I do a ping localhost C:>ping localhost Unable to contact IP driver, error code 2 Moveover, with ipconfig I get this : Windows IP Configuration An internal error occurred: The request is not supported. Please contact Microsoft Product Support Services for further help. Additional Information: Unable to query host name On some further poking around, I saw that none of the "NETWORK SERVICE" process in task manager, except svchost.exe were running. Also, when I first opened the task manager, I saw some 20 processes running with username column empty for most of them. With some search in Google, I found out that these services were important, DHCP DNS Net logon Network connection Network location Awareness TCP/IP Net BIOS Helper none of them, except Network Connections are working, they do not start. The event viewer of my system shows a bunch of 7000 and 7001 event errors. I have tried re installing the network driver, booting in safe mode with networking and tried to enable those services mentioned above. I had disabled System Restore some time back, so I have no restore points for my system. I tried a lot of things from Google searches but none of them worked. Also, with such a long list of issue, I am a little confused as to what should I search on the internet. :( One more thing I would like to mention, previous morning, my anti-virus Avast detected a RootKit buried deep in my system folders. It was removed, but maybe this was a problem caused by the root kit. I did run a boot-time scan but no viruses were found. Please please please advice. Is formatting and re-installation of Windows my only option?

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• Hardware for multipurpose home server

  - by Michael Dmitry Azarkevich

  Hi guys, I'm looking to set up a multipurpose home server and hoped you could help me with the hardware selection. First of all, the services it will provide: Hosting a MySQL database (for training and testing purposes) FTP server Personal Mail Server Home media server So with this in mind I've done some research, and found some viable solutions: A standard PC with the appropriate software (Either second hand or new) A non-solid state mini-ITX system A solid state, fanless mini-ITX system I've also noted the pros and cons of each system: A standard second hand PC with old hardware would be the cheapest option. It could also have lacking processing power, not enough RAM and generally faulty hardware. Also, huge power consumption heat generation and noise levels. A standard new PC would have top-notch hardware and will stay that way for quite some time, so it's a good investment. But again, the main problem is power consumption, heat generation and noise levels. A non-solid state mini-ITX system would have the advantages of lower power consumption, lower cost (as far as I can see) and long lasting hardware. But it will generate noise and heat which will be even worse because of the size. A solid state, fanless mini-ITX system would have all the advantages of a non-solid state mini-ITX but with minimal noise and heat. The main disadvantage is the read\write problems of flash memory. All in all I'm leaning towards a non-solid state mini-ITX because of the read\write issues of flash memory. So, after this overview of what I do know, my questions are: Are all these services even providable from a single server? To my best understanding they are, but then again, I might be wrong. Is any of these solutions viable? If yes, which one is the best for my purposes? If not, what would you suggest? Also, on a more software oriented note: OS wise, I'm planning to run Linux. I'm currently thinking of four options I've been recommended: CentOS, Gentoo, DSL (Damn Small Linux) and LFS (Linux From Scratch). Any thoughts on this? Any other distro you would recomend? Regarding FTP services, I've herd good things about FileZila. Anyone has any experience with that? Do you recommend it? Do you recommend something else? Regarding the Mail service, I know nothing about this except that it exists. Any software you recommend for this task? Home media, same as mail service. Any recommended software? Thank you very much.

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• TrueCrypt partition will no longer mount

  - by sparkyuiop

  I am hoping for some advice to help me out of my situation, with luck. I have a computer running Windows 7 Ultimate x64 with 3 hard disks installed. On my 2TB hard disk 2 (non-system disk) I have 4 partitions. One is for music, another for video, a downloads partition and a 500GB RAW Truecrypt encrypted partition / volume that I had setup to mount with 4 photographs used as keyfiles. The 4 photographs are located in my 'Documents' partition which is one of four partitions on my 1.5TB hard disk 1 (non-system disk) When I setup the disk encryption I did not (I'm 99% sure) create a password, I only used the 4 photograph keyfiles to mount the volume. Recently my 1TB hard disk 0 (system / boot) started to fail so I decided to replace it. I was going to clone the old disk to a new disk but decided that a fresh installation would be more beneficial. Once I had transferred all the required 'User Data' from my old hard disk 0 (C: disk) I discarded it. I reinstalled Truecrypt, pointed to the partition, selected my 4 keyfiles photographs and I mounted my encrypted volume with no issues. In fact I mounted it several times after re-installing Windows and after reboots. Now all of a sudden when I try and mount it I get the message "incorrect keyfile(s) and/or password or not a Truecrypt volume". Now I am not sure why this happened as I do not recall exactly what I did between last mounting the volume successfully and it not mounting. Here are some of the possible things I may have done to cause it to stop working but I am at a loss as to where to start to try and resolve the problem. 1. I had swapped the drive letters to a preferred order. 2. I possibly swapped the physical SATA connectors on the mainboard. 3. I enabled 'Hot Plugging' for the two non-system hard disk SATA ports and the DVD SATA port in the BIOS. I have tried changing the encrypted partition drive letter as suggested in another post but this does not help. On my old system the encrypted drive was drive "X". I have about tried it with all the other free drive letters but alas nothing changes. I do not recall what drive letter was allocated to the encrypted partition before I changed them all. I have not tried to change the letter back to what it possibly was to start with as I am happy with the current layout. I will try this is anyone thinks it would be worthwhile though. I do hope I have managed to convey my situation in an understandable manner and live in hope someone could help me recover years of personal files. Thank you very much for taking the time to read my post and for any suggestions you may offer. Regards Phillip Thorne (UK) Anyone???

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• ASP.NET Web API Exception Handling

  - by Fredrik N

  When I talk about exceptions in my product team I often talk about two kind of exceptions, business and critical exceptions. Business exceptions are exceptions thrown based on “business rules”, for example if you aren’t allowed to do a purchase. Business exceptions in most case aren’t important to log into a log file, they can directly be shown to the user. An example of a business exception could be "DeniedToPurchaseException”, or some validation exceptions such as “FirstNameIsMissingException” etc. Critical Exceptions are all other kind of exceptions such as the SQL server is down etc. Those kind of exception message need to be logged and should not reach the user, because they can contain information that can be harmful if it reach out to wrong kind of users. I often distinguish business exceptions from critical exceptions by creating a base class called BusinessException, then in my error handling code I catch on the type BusinessException and all other exceptions will be handled as critical exceptions. This blog post will be about different ways to handle exceptions and how Business and Critical Exceptions could be handled. Web API and Exceptions the basics When an exception is thrown in a ApiController a response message will be returned with a status code set to 500 and a response formatted by the formatters based on the “Accept” or “Content-Type” HTTP header, for example JSON or XML. Here is an example:   public IEnumerable<string> Get() { throw new ApplicationException("Error!!!!!"); return new string[] { "value1", "value2" }; } .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; } The response message will be: HTTP/1.1 500 Internal Server Error Content-Length: 860 Content-Type: application/json; charset=utf-8 { "ExceptionType":"System.ApplicationException","Message":"Error!!!!!","StackTrace":" at ..."} .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; }   The stack trace will be returned to the client, this is because of making it easier to debug. Be careful so you don’t leak out some sensitive information to the client. So as long as you are developing your API, this is not harmful. In a production environment it can be better to log exceptions and return a user friendly exception instead of the original exception. There is a specific exception shipped with ASP.NET Web API that will not use the formatters based on the “Accept” or “Content-Type” HTTP header, it is the exception is the HttpResponseException class. Here is an example where the HttpReponseExcetpion is used: // GET api/values [ExceptionHandling] public IEnumerable<string> Get() { throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError)); return new string[] { "value1", "value2" }; } .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; } The response will not contain any content, only header information and the status code based on the HttpStatusCode passed as an argument to the HttpResponseMessage. Because the HttpResponsException takes a HttpResponseMessage as an argument, we can give the response a content: public IEnumerable<string> Get() { throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent("My Error Message"), ReasonPhrase = "Critical Exception" }); return new string[] { "value1", "value2" }; } .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; }   The code above will have the following response:   HTTP/1.1 500 Critical Exception Content-Length: 5 Content-Type: text/plain; charset=utf-8 My Error Message .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; } The Content property of the HttpResponseMessage doesn’t need to be just plain text, it can also be other formats, for example JSON, XML etc. By using the HttpResponseException we can for example catch an exception and throw a user friendly exception instead: public IEnumerable<string> Get() { try { DoSomething(); return new string[] { "value1", "value2" }; } catch (Exception e) { throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent("An error occurred, please try again or contact the administrator."), ReasonPhrase = "Critical Exception" }); } } .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; }   Adding a try catch to every ApiController methods will only end in duplication of code, by using a custom ExceptionFilterAttribute or our own custom ApiController base class we can reduce code duplicationof code and also have a more general exception handler for our ApiControllers . By creating a custom ApiController’s and override the ExecuteAsync method, we can add a try catch around the base.ExecuteAsync method, but I prefer to skip the creation of a own custom ApiController, better to use a solution that require few files to be modified. The ExceptionFilterAttribute has a OnException method that we can override and add our exception handling. Here is an example: using System; using System.Diagnostics; using System.Net; using System.Net.Http; using System.Web.Http; using System.Web.Http.Filters; public class ExceptionHandlingAttribute : ExceptionFilterAttribute { public override void OnException(HttpActionExecutedContext context) { if (context.Exception is BusinessException) { throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent(context.Exception.Message), ReasonPhrase = "Exception" }); } //Log Critical errors Debug.WriteLine(context.Exception); throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent("An error occurred, please try again or contact the administrator."), ReasonPhrase = "Critical Exception" }); } } .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; }   Note: Something to have in mind is that the ExceptionFilterAttribute will be ignored if the ApiController action method throws a HttpResponseException. The code above will always make sure a HttpResponseExceptions will be returned, it will also make sure the critical exceptions will show a more user friendly message. The OnException method can also be used to log exceptions. By using a ExceptionFilterAttribute the Get() method in the previous example can now look like this: public IEnumerable<string> Get() { DoSomething(); return new string[] { "value1", "value2" }; } .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; } To use the an ExceptionFilterAttribute, we can for example add the ExceptionFilterAttribute to our ApiControllers methods or to the ApiController class definition, or register it globally for all ApiControllers. You can read more about is here. Note: If something goes wrong in the ExceptionFilterAttribute and an exception is thrown that is not of type HttpResponseException, a formatted exception will be thrown with stack trace etc to the client. How about using a custom IHttpActionInvoker? We can create our own IHTTPActionInvoker and add Exception handling to the invoker. The IHttpActionInvoker will be used to invoke the ApiController’s ExecuteAsync method. Here is an example where the default IHttpActionInvoker, ApiControllerActionInvoker, is used to add exception handling: public class MyApiControllerActionInvoker : ApiControllerActionInvoker { public override Task<HttpResponseMessage> InvokeActionAsync(HttpActionContext actionContext, System.Threading.CancellationToken cancellationToken) { var result = base.InvokeActionAsync(actionContext, cancellationToken); if (result.Exception != null && result.Exception.GetBaseException() != null) { var baseException = result.Exception.GetBaseException(); if (baseException is BusinessException) { return Task.Run<HttpResponseMessage>(() => new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent(baseException.Message), ReasonPhrase = "Error" }); } else { //Log critical error Debug.WriteLine(baseException); return Task.Run<HttpResponseMessage>(() => new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent(baseException.Message), ReasonPhrase = "Critical Error" }); } } return result; } } .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; } You can register the IHttpActionInvoker with your own IoC to resolve the MyApiContollerActionInvoker, or add it in the Global.asax: GlobalConfiguration.Configuration.Services.Remove(typeof(IHttpActionInvoker), GlobalConfiguration.Configuration.Services.GetActionInvoker()); GlobalConfiguration.Configuration.Services.Add(typeof(IHttpActionInvoker), new MyApiControllerActionInvoker()); .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; }   How about using a Message Handler for Exception Handling? By creating a custom Message Handler, we can handle error after the ApiController and the ExceptionFilterAttribute is invoked and in that way create a global exception handler, BUT, the only thing we can take a look at is the HttpResponseMessage, we can’t add a try catch around the Message Handler’s SendAsync method. The last Message Handler that will be used in the Wep API pipe-line is the HttpControllerDispatcher and this Message Handler is added to the HttpServer in an early stage. The HttpControllerDispatcher will use the IHttpActionInvoker to invoke the ApiController method. The HttpControllerDipatcher has a try catch that will turn ALL exceptions into a HttpResponseMessage, so that is the reason why a try catch around the SendAsync in a custom Message Handler want help us. If we create our own Host for the Wep API we could create our own custom HttpControllerDispatcher and add or exception handler to that class, but that would be little tricky but is possible. We can in a Message Handler take a look at the HttpResponseMessage’s IsSuccessStatusCode property to see if the request has failed and if we throw the HttpResponseException in our ApiControllers, we could use the HttpResponseException and give it a Reason Phrase and use that to identify business exceptions or critical exceptions. I wouldn’t add an exception handler into a Message Handler, instead I should use the ExceptionFilterAttribute and register it globally for all ApiControllers. BUT, now to another interesting issue. What will happen if we have a Message Handler that throws an exception?  Those exceptions will not be catch and handled by the ExceptionFilterAttribute. I found a  bug in my previews blog post about “Log message Request and Response in ASP.NET WebAPI” in the MessageHandler I use to log incoming and outgoing messages. Here is the code from my blog before I fixed the bug:   public abstract class MessageHandler : DelegatingHandler { protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) { var corrId = string.Format("{0}{1}", DateTime.Now.Ticks, Thread.CurrentThread.ManagedThreadId); var requestInfo = string.Format("{0} {1}", request.Method, request.RequestUri); var requestMessage = await request.Content.ReadAsByteArrayAsync(); await IncommingMessageAsync(corrId, requestInfo, requestMessage); var response = await base.SendAsync(request, cancellationToken); var responseMessage = await response.Content.ReadAsByteArrayAsync(); await OutgoingMessageAsync(corrId, requestInfo, responseMessage); return response; } protected abstract Task IncommingMessageAsync(string correlationId, string requestInfo, byte[] message); protected abstract Task OutgoingMessageAsync(string correlationId, string requestInfo, byte[] message); } .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; }   If a ApiController throws a HttpResponseException, the Content property of the HttpResponseMessage from the SendAsync will be NULL. So a null reference exception is thrown within the MessageHandler. The yellow screen of death will be returned to the client, and the content is HTML and the Http status code is 500. The bug in the MessageHandler was solved by adding a check against the HttpResponseMessage’s IsSuccessStatusCode property: public abstract class MessageHandler : DelegatingHandler { protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) { var corrId = string.Format("{0}{1}", DateTime.Now.Ticks, Thread.CurrentThread.ManagedThreadId); var requestInfo = string.Format("{0} {1}", request.Method, request.RequestUri); var requestMessage = await request.Content.ReadAsByteArrayAsync(); await IncommingMessageAsync(corrId, requestInfo, requestMessage); var response = await base.SendAsync(request, cancellationToken); byte[] responseMessage; if (response.IsSuccessStatusCode) responseMessage = await response.Content.ReadAsByteArrayAsync(); else responseMessage = Encoding.UTF8.GetBytes(response.ReasonPhrase); await OutgoingMessageAsync(corrId, requestInfo, responseMessage); return response; } protected abstract Task IncommingMessageAsync(string correlationId, string requestInfo, byte[] message); protected abstract Task OutgoingMessageAsync(string correlationId, string requestInfo, byte[] message); } .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; } If we don’t handle the exceptions that can occur in a custom Message Handler, we can have a hard time to find the problem causing the exception. The savior in this case is the Global.asax’s Application_Error: protected void Application_Error() { var exception = Server.GetLastError(); Debug.WriteLine(exception); } .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; } I would recommend you to add the Application_Error to the Global.asax and log all exceptions to make sure all kind of exception is handled. Summary There are different ways we could add Exception Handling to the Wep API, we can use a custom ApiController, ExceptionFilterAttribute, IHttpActionInvoker or Message Handler. The ExceptionFilterAttribute would be a good place to add a global exception handling, require very few modification, just register it globally for all ApiControllers, even the IHttpActionInvoker can be used to minimize the modifications of files. Adding the Application_Error to the global.asax is a good way to catch all unhandled exception that can occur, for example exception thrown in a Message Handler.   If you want to know when I have posted a blog post, you can follow me on twitter @fredrikn

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• The 35 Best Tips and Tricks for Maintaining Your Windows PC

  - by Lori Kaufman

  When working (or playing) on your computer, you probably don’t think much about how you are going to clean up your files, backup your data, keep your system virus free, etc. However, these are tasks that need attention. We’ve published useful article about different aspects of maintaining your computer. Below is a list our most useful articles about maintaining your computer, operating system, software, and data. HTG Explains: Learn How Websites Are Tracking You Online Here’s How to Download Windows 8 Release Preview Right Now HTG Explains: Why Linux Doesn’t Need Defragmenting

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• How to Add Proprietary Drivers to Ubuntu 10.04

  - by Matthew Guay

  Does the hardware on your Ubuntu system need proprietary drivers work at peak performance?  Today we take a look how easy version 10.04 makes it to install them. Ubuntu 10.04 finally automatically recognizes and installs drivers for most hardware today, it even recognized and configured Wi-Fi drivers correctly every time in our tests.  This is in contrast to the past, when it was often difficult to get hardware to work in Linux.  However, most video cards still need proprietary drivers from their manufacturer to get full hardware video acceleration. Even though Ubuntu doesn’t include any non-open source components, it still makes it easy to install proprietary drivers if you wish.  When you first install and boot into Ubuntu, you may see a popup informing you that “restricted” drivers are available. You may see a notification asking you if you’d like to install optional drivers from your graphics card manufacturer when you try to enable advanced desktop effects.  Click Enable to directly install the drivers right there. Or, you can select the tray icon from the first popup, and click Install drivers. Alternately, if the tray icon has disappeared, click System, then Administration, and select Hardware Drivers.   This will open a dialog showing all the proprietary drivers available for your system, which may include drivers for your video card and other hardware depending on your computer.  Select the driver you wish to install, and click Activate. Enter your password, and then Ubuntu will download and install the driver without any more input.  After installation you may be prompted to reboot your system. Now, you should be able to take full advantage of your hardware, including fancy desktop effects with hardware acceleration. If you ever wish to remove these drivers, simply re-open the drivers dialog as above, select the driver, and click Remove.  Once again, a reboot may be required to finish the process. Conclusion Ubuntu has definitely made it easier to use Linux on your desktop computer, no matter what hardware you have.  If your video card or other hardware require proprietary drivers, it makes them available and simple to install.  And, best of all, all of your drivers stay updated with your software updates, so you can be sure you’re always running the latest. Similar Articles Productive Geek Tips Adding extra Repositories on UbuntuBackup and Restore Hardware Drivers the Easy Way with Double DriverCopy Windows Drivers From One Machine to AnotherInstalling PHP4 and Apache on UbuntuInstalling PHP5 and Apache on Ubuntu 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 CloudBerry Online Backup 1.5 for Windows Home Server Snagit 10 VMware Workstation 7 Acronis Online Backup Gmail Button Addon (Firefox) Hyperwords addon (Firefox) Backup Outlook 2010 Daily Motivator (Firefox) FetchMp3 Can Download Videos & Convert Them to Mp3 Use Flixtime To Create Video Slideshows

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• Oracle Linux 6 DVDs Now Available

  - by sergio.leunissen

  On Sunday 6 February 2011, Oracle Linux 6 was released on the Unbreakable Linux Network for customers with an Oracle Linux support subscription. Shortly after that, the Oracle Linux 6 RPMs were made available on our public yum server. Today we published the installation DVD images on edelivery.oracle.com/linux. Oracle Linux 6 is free to download, install and use. The full release notes are here, but similar to my recent post about Oracle Linux 5.6, I wanted to highlight a few items about this release. Unbreakable Enterprise Kernel As is the case with Oracle Linux 5.6, the default installed kernel on x86_64 platform in Oracle Linux 6 is the Unbreakable Enterprise Kernel. If you haven't already, I highly recommend you watch the replay of this webcast by Chris Mason on the performance improvements made in this kernel. # uname -r 2.6.32-100.28.5.el6.x86_64 The Unbreakable Enterprise Kernel is delivered via the package kernel-uek: [root@localhost ~]# yum info kernel-uek ... Installed Packages Name : kernel-uek Arch : x86_64 Version : 2.6.32 Release : 100.28.5.el6 Size : 84 M Repo : installed From repo : anaconda-OracleLinuxServer-201102031546.x86_64 Summary : The Linux kernel URL : http://www.kernel.org/ License : GPLv2 Description: The kernel package contains the Linux kernel (vmlinuz), the core of : any Linux operating system. The kernel handles the basic functions : of the operating system: memory allocation, process allocation, : device input and output, etc. ext4 file system The ext4 or fourth extended filesystem replaces ext3 as the default filesystem in Oracle Linux 6. # mount /dev/mapper/VolGroup-lv_root on / type ext4 (rw) proc on /proc type proc (rw) sysfs on /sys type sysfs (rw) devpts on /dev/pts type devpts (rw,gid=5,mode=620) tmpfs on /dev/shm type tmpfs (rw,rootcontext="system_u:object_r:tmpfs_t:s0") /dev/sda1 on /boot type ext4 (rw) none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw) Red Hat compatible kernel Oracle Linux 6 also includes a Red Hat compatible kernel built directly from RHEL source. It's already installed, so booting it is a matter of editing /etc/grub.conf # rpm -qa | grep kernel-2.6.32 kernel-2.6.32-71.el6.x86_64 Oracle Linux 6 no longer includes a Red Hat compatible kernel with Oracle bug fixes. The only Red Hat compatible kernel included is the one built directly from RHEL source. Yum-only access to Unbreakable Linux Network (ULN) Oracle Linux 6 uses yum exclusively for access to Unbreakable Linux Network. To register your system with ULN, use the following command: # uln_register No Itanium Support Oracle Linux 6 is not supported on the Itanium (ia64) platform. Next Steps Read the release notes Download Oracle Linux 6 for free Discuss on the Oracle Linux forum

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• How do I get an Enter USB TV Box TV tuner aka Gadmei UTV302 to work?

  - by Subhash

  Has anyone had any success in using the Enter USB TV Box from Enter Multimedia? It comes bundled with software that works in Windows. I have had no luck using it in Ubuntu 10.10. Update 1 Here is the output from lsusb Bus 007 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 006 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 004 Device 003: ID 093a:2510 Pixart Imaging, Inc. Optical Mouse Bus 004 Device 002: ID 046d:c312 Logitech, Inc. DeLuxe 250 Keyboard Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 001 Device 006: ID 1f71:3301 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub I can't find the Enter USB TV Box listed in this. In the dmesg tail command, I found something that seems to be related to the card: usb 1-5: new high speed USB device using ehci_hcd and address 6 usb 1-5: config 1 interface 0 altsetting 1 bulk endpoint 0x83 has invalid maxpacket 256 Update 2 From Windows I learned that this USB TV tuner uses some chipset from Gadmei corporation. All computer stores in India sell Enter USB TV Box if you ask for an USB TV tuner. No other brand seems to be interested in this market. Update 3 I learned that this TV tuner is rebranded version of Gadmei UTV302 (USB TV Tuner Box). Update 4 I tried adding em28xx as the chipset (as suggested by user BOBBO below) for the tuner but that did not work. I went back to my Pinnacle PCTV internal card. I don't think the tuner referred by UbuntuForums (Gadmei UTV 330) and the tuner that I have (Gadmei UTV 302) are the same. My USB tuner is several times bigger. My tuner seems to be a newer device with a newer tuner chip. I will submit details of this device to the LinuxTV developers this weekend. Update 5 I opened the tuner box and found that it uses a tuner from a Chinese company - Tenas. Model is TNF 8022-DFA. Update 6 Tuner chip specs (retrived from supplier directory) for Tenas TNF 8022-DFA. Supply voltage: true 5V device(low power dissipation) Control system: I2C bus control of tuning, address selection Tuning system: PLL controlled tuning Receiving system: system PAL D/K,IF(Intermediate Frequency): 38MHz Receiving channels: full frequency range from channel DS1 (49.75MHz) to channel DS57 (863.25MHz); Use Texas Instruments SN761678 IC solution, with mini install size Update 7 Reverse side of the circuit board. Picture of the TV tuner

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• Using linked servers, OPENROWSET and OPENQUERY

  - by BuckWoody

  SQL Server has a few mechanisms to reach out to another server (even another server type) and query data from within a Transact-SQL statement. Among them are a set of stored credentials and information (called a Linked Server), a statement that uses a linked server called called OPENQUERY, another called OPENROWSET, and one called OPENDATASOURCE. This post isn’t about those particular functions or statements – hit the links for more if you’re new to those topics. I’m actually more concerned about where I see these used than the particular method. In many cases, a Linked server isn’t another Relational Database Management System (RDMBS) like Oracle or DB2 (which is possible with a linked server), but another SQL Server. My concern is that linked servers are the new Data Transformation Services (DTS) from SQL Server 2000 – something that was designed for one purpose but which is being morphed into something much more. In the case of DTS, most of us turned that feature into a full-fledged job system. What was designed as a simple data import and export system has been pressed into service doing logic, routing and timing. And of course we all know how painful it was to move off of a complex DTS system onto SQL Server Integration Services. In the case of linked servers, what should be used as a method of running a simple query or two on another server where you have occasional connection or need a quick import of a small data set is morphing into a full federation strategy. In some cases I’ve seen a complex web of linked servers, and when credentials, names or anything else changes there are huge problems. Now don’t get me wrong – linked servers and other forms of distributing queries is a fantastic set of tools that we have to move data around. I’m just saying that when you start having lots of workarounds and when things get really complicated, you might want to step back a little and ask if there’s a better way. Are you able to tolerate some latency? Perhaps you’re able to use Service Broker. Would you like to be platform-independent on the data source? Perhaps a middle-tier might make more sense, abstracting the queries there and sending them to the proper server. Designed properly, I’ve seen these systems scale further and be more resilient than loading up on linked servers. Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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