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  • What is the best workaround for the WCF client `using` block issue?

    - by Eric King
    I like instantiating my WCF service clients within a using block as it's pretty much the standard way to use resources that implement IDisposable: using (var client = new SomeWCFServiceClient()) { //Do something with the client } But, as noted in this MSDN article, wrapping a WCF client in a using block could mask any errors that result in the client being left in a faulted state (like a timeout or communication problem). Long story short, when Dispose() is called, the client's Close() method fires, but throws and error because it's in a faulted state. The original exception is then masked by the second exception. Not good. The suggested workaround in the MSDN article is to completely avoid using a using block, and to instead instantiate your clients and use them something like this: try { ... client.Close(); } catch (CommunicationException e) { ... client.Abort(); } catch (TimeoutException e) { ... client.Abort(); } catch (Exception e) { ... client.Abort(); throw; } Compared to the using block, I think that's ugly. And a lot of code to write each time you need a client. Luckily, I found a few other workarounds, such as this one on IServiceOriented. You start with: public delegate void UseServiceDelegate<T>(T proxy); public static class Service<T> { public static ChannelFactory<T> _channelFactory = new ChannelFactory<T>(""); public static void Use(UseServiceDelegate<T> codeBlock) { IClientChannel proxy = (IClientChannel)_channelFactory.CreateChannel(); bool success = false; try { codeBlock((T)proxy); proxy.Close(); success = true; } finally { if (!success) { proxy.Abort(); } } } } Which then allows: Service<IOrderService>.Use(orderService => { orderService.PlaceOrder(request); } That's not bad, but I don't think it's as expressive and easily understandable as the using block. The workaround I'm currently trying to use I first read about on blog.davidbarret.net. Basically you override the client's Dispose() method wherever you use it. Something like: public partial class SomeWCFServiceClient : IDisposable { void IDisposable.Dispose() { if (this.State == CommunicationState.Faulted) { this.Abort(); } else { this.Close(); } } } This appears to be able to allow the using block again without the danger of masking a faulted state exception. So, are there any other gotchas I have to look out for using these workarounds? Has anybody come up with anything better?

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  • Create UserControl DependencyProperty of which value can be chosen in dropdown list (as combo box)

    - by Viet
    Hello everybody, I'm a starter at WPF, now i would like to make a WPF userControl library which include a Rating bar userControl. All the steps of creating the rating Bar has been done, however i would like to add a property RatingValue: public static readonly DependencyProperty RatingValueProperty = DependencyProperty.Register("RatingValue", typeof(int), typeof(RatingControl), new FrameworkPropertyMetadata(0, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, new PropertyChangedCallback(RatingValueChanged))); public int RatingValue { get { return (int)GetValue(RatingValueProperty); } set { SetValue(RatingValueProperty, value); } } private static void RatingValueChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e) { //... change the rating value } that the user of my UserControl can modify by a value from 0 to 5 that are shown in a dropdown list (combo box) in the Properties windows (as some exist properties of Usercontrols like Visibility, windows style, background ...) How can i do? Thank you very much in advance, Viet

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  • C# TraceSource class in multithreaded application

    - by matti
    msdn: "Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe." it contains only instance methods. How should I use it in a way that all activity gets recorder by TextWriterTraceListener to a text file. Is one static member which all threads use (by calling) TraceEvent-method safe. (I've kind of asked this question in http://stackoverflow.com/questions/1901086/how-to-instantiate-c-tracesources-to-log-multithreaded-asp-net-2-0-web-applica, but I cannot just believe if somebody just says it's OK despite the documentation).

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  • System.AccessViolation in DllImport method after redeploy

    - by gall
    Hi Everyone, My environment: Windows 2003, VS 2008, .NET 3.5 C# .NET application. During loading my application I call method from C++ dll (Knowl.dll) through my third-party dll library (Common.dll) written in C#. After first deploy (from VS to Developing server) evrything works fine. Then I stops Developing Server, doesn't any changes in code and redeploy. Throws AccessViolationException on this imported method. What is it? On second and after redeplies - the same error. Only after deletin source code and recheckout it from CVS I can normally start server. Dll import: [DllImport("Knowl.dll", EntryPoint = "GetBaseName")] private static extern IntPtr getNameDll(); public static string GetName() { IntPtr p = IntPtr.Zero; p = getNameDll(); return Marshal.PtrToStringUni(p); }

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  • Java OutOfMemoryError strange behaviour

    - by Evgeniy Dorofeev
    Assuming we have a max memory of 256M, why does this code work: public static void main(String... args) { for (int i = 0; i < 2; i++) { byte[] a1 = new byte[150000000]; } byte[] a2 = new byte[150000000]; } but this one throw an OOME? public static void main(String... args) { //for (int i = 0; i < 2; i++) { byte[] a1 = new byte[150000000]; } byte[] a2 = new byte[150000000]; }

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  • ASP.NET MVC2 custom rolemanager (webconfig problem)

    - by ile
    Structure of the web: SAMembershipProvider.cs namespace User.Membership { public class SAMembershipProvider : MembershipProvider { #region - Properties - private int NewPasswordLength { get; set; } private string ConnectionString { get; set; } //private MachineKeySection MachineKey { get; set; } //Used when determining encryption key values. public bool enablePasswordReset { get; set; } public bool enablePasswordRetrieval { get; set; } public bool requiresQuestionAndAnswer { get; set; } public bool requiresUniqueEmail { get; set; } public int maxInvalidPasswordAttempts { get; set; } public int passwordAttemptWindow { get; set; } public MembershipPasswordFormat passwordFormat { get; set; } public int minRequiredNonAlphanumericCharacters { get; set; } public int minRequiredPasswordLength { get; set; } public string passwordStrengthRegularExpression { get; set; } public override string ApplicationName { get; set; } // Indicates whether passwords can be retrieved using the provider's GetPassword method. // This property is read-only. public override bool EnablePasswordRetrieval { get { return enablePasswordRetrieval; } } // Indicates whether passwords can be reset using the provider's ResetPassword method. // This property is read-only. public override bool EnablePasswordReset { get { return enablePasswordReset; } } // Indicates whether a password answer must be supplied when calling the provider's GetPassword and ResetPassword methods. // This property is read-only. public override bool RequiresQuestionAndAnswer { get { return requiresQuestionAndAnswer; } } public override int MaxInvalidPasswordAttempts { get { return maxInvalidPasswordAttempts; } } // For a description, see MaxInvalidPasswordAttempts. // This property is read-only. public override int PasswordAttemptWindow { get { return passwordAttemptWindow; } } // Indicates whether each registered user must have a unique e-mail address. // This property is read-only. public override bool RequiresUniqueEmail { get { return requiresUniqueEmail; } } public override MembershipPasswordFormat PasswordFormat { get { return passwordFormat; } } // The minimum number of characters required in a password. // This property is read-only. public override int MinRequiredPasswordLength { get { return minRequiredPasswordLength; } } // The minimum number of non-alphanumeric characters required in a password. // This property is read-only. public override int MinRequiredNonAlphanumericCharacters { get { return minRequiredNonAlphanumericCharacters; } } // A regular expression specifying a pattern to which passwords must conform. // This property is read-only. public override string PasswordStrengthRegularExpression { get { return passwordStrengthRegularExpression; } } #endregion #region - Methods - public override void Initialize(string name, NameValueCollection config) { throw new NotImplementedException(); } public override bool ChangePassword(string username, string oldPassword, string newPassword) { throw new NotImplementedException(); } public override bool ChangePasswordQuestionAndAnswer(string username, string password, string newPasswordQuestion, string newPasswordAnswer) { throw new NotImplementedException(); } // Takes, as input, a user name, password, e-mail address, and other information and adds a new user // to the membership data source. CreateUser returns a MembershipUser object representing the newly // created user. It also accepts an out parameter (in Visual Basic, ByRef) that returns a // MembershipCreateStatus value indicating whether the user was successfully created or, if the user // was not created, the reason why. If the user was not created, CreateUser returns null. // Before creating a new user, CreateUser calls the provider's virtual OnValidatingPassword method to // validate the supplied password. It then creates the user or cancels the action based on the outcome of the call. public override MembershipUser CreateUser(string username, string password, string email, string passwordQuestion, string passwordAnswer, bool isApproved, object providerUserKey, out MembershipCreateStatus status) { throw new NotImplementedException(); } public override bool DeleteUser(string username, bool deleteAllRelatedData) { throw new NotImplementedException(); } public override MembershipUserCollection FindUsersByEmail(string emailToMatch, int pageIndex, int pageSize, out int totalRecords) { throw new NotImplementedException(); } // Returns a MembershipUserCollection containing MembershipUser objects representing users whose user names // match the usernameToMatch input parameter. Wildcard syntax is data source-dependent. MembershipUser objects // in the MembershipUserCollection are sorted by user name. If FindUsersByName finds no matching users, it // returns an empty MembershipUserCollection. // For an explanation of the pageIndex, pageSize, and totalRecords parameters, see the GetAllUsers method. public override MembershipUserCollection FindUsersByName(string usernameToMatch, int pageIndex, int pageSize, out int totalRecords) { throw new NotImplementedException(); } // Returns a MembershipUserCollection containing MembershipUser objects representing all registered users. If // there are no registered users, GetAllUsers returns an empty MembershipUserCollection // The results returned by GetAllUsers are constrained by the pageIndex and pageSize input parameters. pageSize // specifies the maximum number of MembershipUser objects to return. pageIndex identifies which page of results // to return. Page indexes are 0-based. // // GetAllUsers also takes an out parameter (in Visual Basic, ByRef) named totalRecords that, on return, holds // a count of all registered users. public override MembershipUserCollection GetAllUsers(int pageIndex, int pageSize, out int totalRecords) { throw new NotImplementedException(); } // Returns a count of users that are currently online-that is, whose LastActivityDate is greater than the current // date and time minus the value of the membership service's UserIsOnlineTimeWindow property, which can be read // from Membership.UserIsOnlineTimeWindow. UserIsOnlineTimeWindow specifies a time in minutes and is set using // the <membership> element's userIsOnlineTimeWindow attribute. public override int GetNumberOfUsersOnline() { throw new NotImplementedException(); } // Takes, as input, a user name and a password answer and returns that user's password. If the user name is not // valid, GetPassword throws a ProviderException. // Before retrieving a password, GetPassword verifies that EnablePasswordRetrieval is true. If // EnablePasswordRetrieval is false, GetPassword throws a NotSupportedException. If EnablePasswordRetrieval is // true but the password format is hashed, GetPassword throws a ProviderException since hashed passwords cannot, // by definition, be retrieved. A membership provider should also throw a ProviderException from Initialize if // EnablePasswordRetrieval is true but the password format is hashed. // // GetPassword also checks the value of the RequiresQuestionAndAnswer property before retrieving a password. If // RequiresQuestionAndAnswer is true, GetPassword compares the supplied password answer to the stored password // answer and throws a MembershipPasswordException if the two don't match. GetPassword also throws a // MembershipPasswordException if the user whose password is being retrieved is currently locked out. public override string GetPassword(string username, string answer) { throw new NotImplementedException(); } // Takes, as input, a user name or user ID (the method is overloaded) and a Boolean value indicating whether // to update the user's LastActivityDate to show that the user is currently online. GetUser returns a MembershipUser // object representing the specified user. If the user name or user ID is invalid (that is, if it doesn't represent // a registered user) GetUser returns null (Nothing in Visual Basic). public override MembershipUser GetUser(object providerUserKey, bool userIsOnline) { throw new NotImplementedException(); } // Takes, as input, a user name or user ID (the method is overloaded) and a Boolean value indicating whether to // update the user's LastActivityDate to show that the user is currently online. GetUser returns a MembershipUser // object representing the specified user. If the user name or user ID is invalid (that is, if it doesn't represent // a registered user) GetUser returns null (Nothing in Visual Basic). public override MembershipUser GetUser(string username, bool userIsOnline) { throw new NotImplementedException(); } // Takes, as input, an e-mail address and returns the first registered user name whose e-mail address matches the // one supplied. // If it doesn't find a user with a matching e-mail address, GetUserNameByEmail returns an empty string. public override string GetUserNameByEmail(string email) { throw new NotImplementedException(); } // Virtual method called when a password is created. The default implementation in MembershipProvider fires a // ValidatingPassword event, so be sure to call the base class's OnValidatingPassword method if you override // this method. The ValidatingPassword event allows applications to apply additional tests to passwords by // registering event handlers. // A custom provider's CreateUser, ChangePassword, and ResetPassword methods (in short, all methods that record // new passwords) should call this method. protected override void OnValidatingPassword(ValidatePasswordEventArgs e) { base.OnValidatingPassword(e); } // Takes, as input, a user name and a password answer and replaces the user's current password with a new, random // password. ResetPassword then returns the new password. A convenient mechanism for generating a random password // is the Membership.GeneratePassword method. // If the user name is not valid, ResetPassword throws a ProviderException. ResetPassword also checks the value of // the RequiresQuestionAndAnswer property before resetting a password. If RequiresQuestionAndAnswer is true, // ResetPassword compares the supplied password answer to the stored password answer and throws a // MembershipPasswordException if the two don't match. // // Before resetting a password, ResetPassword verifies that EnablePasswordReset is true. If EnablePasswordReset is // false, ResetPassword throws a NotSupportedException. If the user whose password is being changed is currently // locked out, ResetPassword throws a MembershipPasswordException. // // Before resetting a password, ResetPassword calls the provider's virtual OnValidatingPassword method to validate // the new password. It then resets the password or cancels the action based on the outcome of the call. If the new // password is invalid, ResetPassword throws a ProviderException. // // Following a successful password reset, ResetPassword updates the user's LastPasswordChangedDate. public override string ResetPassword(string username, string answer) { throw new NotImplementedException(); } // Unlocks (that is, restores login privileges for) the specified user. UnlockUser returns true if the user is // successfully unlocked. Otherwise, it returns false. If the user is already unlocked, UnlockUser simply returns true. public override bool UnlockUser(string userName) { throw new NotImplementedException(); } // Takes, as input, a MembershipUser object representing a registered user and updates the information stored for // that user in the membership data source. If any of the input submitted in the MembershipUser object is not valid, // UpdateUser throws a ProviderException. // Note that UpdateUser is not obligated to allow all the data that can be encapsulated in a MembershipUser object to // be updated in the data source. public override void UpdateUser(MembershipUser user) { throw new NotImplementedException(); } // Takes, as input, a user name and a password and verifies that they are valid-that is, that the membership data // source contains a matching user name and password. ValidateUser returns true if the user name and password are // valid, if the user is approved (that is, if MembershipUser.IsApproved is true), and if the user isn't currently // locked out. Otherwise, it returns false. // Following a successful validation, ValidateUser updates the user's LastLoginDate and fires an // AuditMembershipAuthenticationSuccess Web event. Following a failed validation, it fires an // // AuditMembershipAuthenticationFailure Web event. public override bool ValidateUser(string username, string password) { throw new NotImplementedException(); //if (string.IsNullOrEmpty(password.Trim())) return false; //string hash = EncryptPassword(password); //User user = _repository.GetByUserName(username); //if (user == null) return false; //if (user.Password == hash) //{ // User = user; // return true; //} //return false; } #endregion /// <summary> /// Procuses an MD5 hash string of the password /// </summary> /// <param name="password">password to hash</param> /// <returns>MD5 Hash string</returns> protected string EncryptPassword(string password) { //we use codepage 1252 because that is what sql server uses byte[] pwdBytes = Encoding.GetEncoding(1252).GetBytes(password); byte[] hashBytes = System.Security.Cryptography.MD5.Create().ComputeHash(pwdBytes); return Encoding.GetEncoding(1252).GetString(hashBytes); } } // End Class } SARoleProvider.cs namespace User.Membership { public class SARoleProvider : RoleProvider { #region - Properties - // The name of the application using the role provider. ApplicationName is used to scope // role data so that applications can choose whether to share role data with other applications. // This property can be read and written. public override string ApplicationName { get; set; } #endregion #region - Methods - public override void Initialize(string name, NameValueCollection config) { throw new NotImplementedException(); } // Takes, as input, a list of user names and a list of role names and adds the specified users to // the specified roles. // AddUsersToRoles throws a ProviderException if any of the user names or role names do not exist. // If any user name or role name is null (Nothing in Visual Basic), AddUsersToRoles throws an // ArgumentNullException. If any user name or role name is an empty string, AddUsersToRoles throws // an ArgumentException. public override void AddUsersToRoles(string[] usernames, string[] roleNames) { throw new NotImplementedException(); } // Takes, as input, a role name and creates the specified role. // CreateRole throws a ProviderException if the role already exists, the role name contains a comma, // or the role name exceeds the maximum length allowed by the data source. public override void CreateRole(string roleName) { throw new NotImplementedException(); } // Takes, as input, a role name and a Boolean value that indicates whether to throw an exception if there // are users currently associated with the role, and then deletes the specified role. // If the throwOnPopulatedRole input parameter is true and the specified role has one or more members, // DeleteRole throws a ProviderException and does not delete the role. If throwOnPopulatedRole is false, // DeleteRole deletes the role whether it is empty or not. // // When DeleteRole deletes a role and there are users assigned to that role, it also removes users from the role. public override bool DeleteRole(string roleName, bool throwOnPopulatedRole) { throw new NotImplementedException(); } // Takes, as input, a search pattern and a role name and returns a list of users belonging to the specified role // whose user names match the pattern. Wildcard syntax is data-source-dependent and may vary from provider to // provider. User names are returned in alphabetical order. // If the search finds no matches, FindUsersInRole returns an empty string array (a string array with no elements). // If the role does not exist, FindUsersInRole throws a ProviderException. public override string[] FindUsersInRole(string roleName, string usernameToMatch) { throw new NotImplementedException(); } // Returns the names of all existing roles. If no roles exist, GetAllRoles returns an empty string array (a string // array with no elements). public override string[] GetAllRoles() { throw new NotImplementedException(); } // Takes, as input, a user name and returns the names of the roles to which the user belongs. // If the user is not assigned to any roles, GetRolesForUser returns an empty string array // (a string array with no elements). If the user name does not exist, GetRolesForUser throws a // ProviderException. public override string[] GetRolesForUser(string username) { throw new NotImplementedException(); //User user = _repository.GetByUserName(username); //string[] roles = new string[user.Role.Rights.Count + 1]; //roles[0] = user.Role.Description; //int idx = 0; //foreach (Right right in user.Role.Rights) // roles[++idx] = right.Description; //return roles; } public override string[] GetUsersInRole(string roleName) { throw new NotImplementedException(); } // Takes, as input, a role name and returns the names of all users assigned to that role. // If no users are associated with the specified role, GetUserInRole returns an empty string array (a string array with // no elements). If the role does not exist, GetUsersInRole throws a ProviderException. public override bool IsUserInRole(string username, string roleName) { throw new NotImplementedException(); //User user = _repository.GetByUserName(username); //if (user != null) // return user.IsInRole(roleName); //else // return false; } // Takes, as input, a list of user names and a list of role names and removes the specified users from the specified roles. // RemoveUsersFromRoles throws a ProviderException if any of the users or roles do not exist, or if any user specified // in the call does not belong to the role from which he or she is being removed. public override void RemoveUsersFromRoles(string[] usernames, string[] roleNames) { throw new NotImplementedException(); } // Takes, as input, a role name and determines whether the role exists. public override bool RoleExists(string roleName) { throw new NotImplementedException(); } #endregion } // End Class } From Web.config: <membership defaultProvider="SAMembershipProvider" userIsOnlineTimeWindow="15"> <providers> <clear/> <add name="SAMembershipProvider" type="User.Membership.SAMembershipProvider, User" /> </providers> </membership> <roleManager defaultProvider="SARoleProvider" enabled="true" cacheRolesInCookie="true"> <providers> <clear/> <add name="SARoleProvider" type="User.Membership.SARoleProvider" /> </providers> </roleManager> When running project, I get following error: Server Error in '/' Application. Configuration Error Description: An error occurred during the processing of a configuration file required to service this request. Please review the specific error details below and modify your configuration file appropriately. Parser Error Message: The method or operation is not implemented. Source Error: Line 71: <providers> Line 72: <clear/> Line 73: <add name="SARoleProvider" type="User.Membership.SARoleProvider" /> Line 74: </providers> Line 75: </roleManager> I tried: <add name="SARoleProvider" type="User.Membership.SARoleProvider, User" /> and <add name="SARoleProvider" type="User.Membership.SARoleProvider, SARoleProvider" /> and <add name="SARoleProvider" type="User.Membership.SARoleProvider, User.Membership" /> but none works Any idea what's wrong here? Thanks, Ile

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  • Populate JSP dropdown with database info

    - by Cano63
    I'm looking for the way to populate a JSP dropdown. I want that when the JSP loads it fills the dropdown with the info that I have in a database table. I'm including the code of my class that will create the array and fill it with the database info. What I don't know is how to call that class from my JSP and fill the dropdown. // this will create my array public static ArrayList<DropDownBrands> getBrandsMakes() { ArrayList<DropDownBrands> arrayBrandsMake = new ArrayList<DropDownBrands>(); while (rs.next()) { arrayBrandsMake.add(loadOB(rs)); // CARGO MI ARREGLO CON UN OBJETO } return arrayBrandsMake; } // this will load my array object private static DropDownBrands loadOB(ResultSet rs) throws SQLException { DropDownBrands OB = new DropDownBrands(); OB.setBrands("BRAN"); return OB; }

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  • Detect Client Computer name when an RDP session is open

    - by Ubiquitous Che
    Hey all, My manager has pointed out to me a few nifty things that one of our accounting applications can do because it can load different settings based on the machine name of the host and the machine name of the client when the package is opened in an RDP session. We want to provide similar functionality in one of my company's applications. I've found out on this site how to detect if I'm in an RDP session, but I'm having trouble finding information anywhere on how to detect the name of the client computer. Any pointers in the right direction would be great. I'm coding in C# for .NET 3.5 EDIT The sample code I cobbled together from the advice below - it should be enough for anyone who has a use for the WTSQuerySessionInformation to get a feel for what's going on. Note that this isn't necessarily the best way of doing it - just a starting point that I've found useful. When I run this locally, I get boring, expected answers. When I run it on our local office server in an RDP session, I see my own computer name in the WTSClientName property. using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Runtime.InteropServices; namespace TerminalServicesTest { class Program { const int WTS_CURRENT_SESSION = -1; static readonly IntPtr WTS_CURRENT_SERVER_HANDLE = IntPtr.Zero; static void Main(string[] args) { StringBuilder sb = new StringBuilder(); uint byteCount; foreach (WTS_INFO_CLASS item in Enum.GetValues(typeof(WTS_INFO_CLASS))) { Program.WTSQuerySessionInformation( WTS_CURRENT_SERVER_HANDLE, WTS_CURRENT_SESSION, item, out sb, out byteCount); Console.WriteLine("{0}({1}): {2}", item.ToString(), byteCount, sb); } Console.WriteLine(); Console.WriteLine("Press any key to exit..."); Console.ReadKey(); } [DllImport("Wtsapi32.dll")] public static extern bool WTSQuerySessionInformation( IntPtr hServer, int sessionId, WTS_INFO_CLASS wtsInfoClass, out StringBuilder ppBuffer, out uint pBytesReturned); } enum WTS_INFO_CLASS { WTSInitialProgram = 0, WTSApplicationName = 1, WTSWorkingDirectory = 2, WTSOEMId = 3, WTSSessionId = 4, WTSUserName = 5, WTSWinStationName = 6, WTSDomainName = 7, WTSConnectState = 8, WTSClientBuildNumber = 9, WTSClientName = 10, WTSClientDirectory = 11, WTSClientProductId = 12, WTSClientHardwareId = 13, WTSClientAddress = 14, WTSClientDisplay = 15, WTSClientProtocolType = 16, WTSIdleTime = 17, WTSLogonTime = 18, WTSIncomingBytes = 19, WTSOutgoingBytes = 20, WTSIncomingFrames = 21, WTSOutgoingFrames = 22, WTSClientInfo = 23, WTSSessionInfo = 24, WTSSessionInfoEx = 25, WTSConfigInfo = 26, WTSValidationInfo = 27, WTSSessionAddressV4 = 28, WTSIsRemoteSession = 29 } }

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  • Android NDK Question

    - by Kyle
    The NDK does not contain very many shared libraries for you to access. As a result, I must build many sources myself and link them into my shared library via static/shared libraries. I want to compile libpng as a Static Library. Trouble is, I have absolutely no idea how, nor does google instruct you how to do so in their NDK. I'm no expert on the NDK even after reading everything I can find, so I would really appreciate someone who actually knows how this is done. I do have the Android.mk file for libpng, as google's Android OS source contains it. Infact, I got the entire directory on the android OS source for libpng and it's dependent libraries. It was somewhat of a shortcut instead of making one myself. I don't know how to make a particular directory which contains this file, though. Thanks for reading!

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  • tripledes encryption not yielding same results in PHP and C#

    - by Jones
    When I encrypt with C# I get arTdPqWOg6VppOqUD6mGITjb24+x5vJjfAufNQ4DN7rVEtpDmhFnMeJGg4n5y1BN static void Main(string[] args) { Encoding byteEncoder = Encoding.Default; String key = "ShHhd8a08JhJiho98ayslcjh"; String message = "Let us meet at 9 o'clock at the secret place."; String encryption = Encrypt(message, key, false); String decryption = Decrypt(encryption , key, false); Console.WriteLine("Message: {0}", message); Console.WriteLine("Encryption: {0}", encryption); Console.WriteLine("Decryption: {0}", decryption); } public static string Encrypt(string toEncrypt, string key, bool useHashing) { byte[] keyArray; byte[] toEncryptArray = UTF8Encoding.UTF8.GetBytes(toEncrypt); if (useHashing) { MD5CryptoServiceProvider hashmd5 = new MD5CryptoServiceProvider(); keyArray = hashmd5.ComputeHash(UTF8Encoding.UTF8.GetBytes(key)); } else keyArray = UTF8Encoding.UTF8.GetBytes(key); TripleDESCryptoServiceProvider tdes = new TripleDESCryptoServiceProvider(); tdes.Key = keyArray; tdes.Mode = CipherMode.ECB; tdes.Padding = PaddingMode.PKCS7; ICryptoTransform cTransform = tdes.CreateEncryptor(); byte[] resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length); return Convert.ToBase64String(resultArray, 0, resultArray.Length); } public static string Decrypt(string toDecrypt, string key, bool useHashing) { byte[] keyArray; byte[] toEncryptArray = Convert.FromBase64String(toDecrypt); if (useHashing) { MD5CryptoServiceProvider hashmd5 = new MD5CryptoServiceProvider(); keyArray = hashmd5.ComputeHash(UTF8Encoding.UTF8.GetBytes(key)); } else keyArray = UTF8Encoding.UTF8.GetBytes(key); TripleDESCryptoServiceProvider tdes = new TripleDESCryptoServiceProvider(); tdes.Key = keyArray; tdes.Mode = CipherMode.ECB; tdes.Padding = PaddingMode.PKCS7; ICryptoTransform cTransform = tdes.CreateDecryptor(); byte[] resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length); return UTF8Encoding.UTF8.GetString(resultArray); } When I encrypt with PHP I get: arTdPqWOg6VppOqUD6mGITjb24+x5vJjfAufNQ4DN7rVEtpDmhFnMVM+W/WFlksR <?php $key = "ShHhd8a08JhJiho98ayslcjh"; $input = "Let us meet at 9 o'clock at the secret place."; $td = mcrypt_module_open('tripledes', '', 'ecb', ''); $iv = mcrypt_create_iv (mcrypt_enc_get_iv_size($td), MCRYPT_RAND); mcrypt_generic_init($td, $key, $iv); $encrypted_data = mcrypt_generic($td, $input); mcrypt_generic_deinit($td); mcrypt_module_close($td); echo base64_encode($encrypted_data); ?> I don't know enough about cryptography to figure out why. Any ideas? Thanks.

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  • Quercus on Google App Engine: Class not loading

    - by gAMBOOKa
    Fatal Error: no matching class connection index.php <?php import database.connection; $connection = connection::get()->getPersistenceManager(); // ***ERROR HERE*** ?> connection.java package database; import javax.jdo.JDOHelper; import javax.jdo.PersistenceManagerFactory; public final class connection { private static final PersistenceManagerFactory pmfInstance = JDOHelper.getPersistenceManagerFactory("transactions-optional"); private connection() {} public static PersistenceManagerFactory get() { return pmfInstance; } } Quercus is otherwise configured fine, PHP implementation works smoothly on GAE. But when I try to initialize classes, PHP can't find them. What am I doing wrong?

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  • Custom ASP.NET MVC cache controllers in a shared hosting environment?

    - by Daniel Crenna
    I'm using custom controllers that cache static resources (CSS, JS, etc.) and images. I'm currently working with a hosting provider that has set me up under a full trust profile. Despite being in full trust, my controllers fail because the caching strategy relies on the File class to directly open a resource file prior to treatment and storage in memory. Is this something that would likely occur in all full trust shared hosting environments or is this specific to my host? The static files live within my application's structure and not in an arbitrary server path. It seems to me that custom caching would require code to access the file directly, and am hoping someone else has dealt with this issue.

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  • load/unload C dll with C# problems

    - by Goran
    I'm having problems with external native DLL. I'm working on ASP.NET 1.1 web application and have this DLL which I load through DLLImport directives. This is how I map DLL functions: [DllImport("somedllname", CallingConvention=CallingConvention.StdCall)] public static extern int function1(string lpFileName,string lpOwnerPw,string lpUserPw); [DllImport("somedllname", CallingConvention=CallingConvention.StdCall)] public static extern int function2(int nHandle); I call the dll methods and all works great, but I have problems with this DLL crashing my web site on some cases, so I would like an option to unload the dll after I use it. I found a solution at this link, but I don't have 'UnmanagedFunctionPointer' attribute in .NET 1.1 available. http://blogs.msdn.com/jonathanswift/archive/2006/10/03/Dynamically-calling-an-unmanaged-dll-from-.NET-_2800_C_23002900_.aspx Is there a way I can achieve what this guy did with his example?

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  • Timeout Considerations for Solicit Response

    - by Michael Stephenson
    Background One of the clients I work with had been experiencing some issues for a while surrounding web service timeouts.  It's been a little challenging to work through the problems due to limitations in the diagnostic information available from one of the applications, but I learned some interesting things while troubleshooting the problem which don't seem to have been discussed much in the community so I thought I'd share my findings. In the scenario we have BizTalk trying to make calls to a .net web service which was exposed as a WSE 2 endpoint.  In the process BizTalk will try to make a large number of concurrent web service calls to the application, and the backend application has more than enough infrastructure and capability to handle the load. We have configured the <ConnectionManagement> section of the BizTalk configuration file to support up to 100 concurrent connections from each of our 2 BizTalk send servers to the web servers of the application. The problem we were facing was that the BizTalk side was reporting a significant number of timeouts when calling the web service.   One of the biggest issues was the challenge of being able to correlate a message from BizTalk to the IIS log in the .net application and the custom logs in the application especially when there was a fairly large number of servers hosting the web services.  However the key moment came when we were able to identify a specific call which had taken 40 seconds to execute on the server (yes a long time I know but that's a different story!).  Anyway we were able to identify that this had timed out on the BizTalk side.  Based on the normal 2 minute timeout we knew something unexpected was going on. From here I decided to do some experimentation and I wanted to start outside of BizTalk because my hunch was this was not a BizTalk behaviour but something which was being highlighted by BizTalk because of our large load.     Server-side - Sample Web Service To begin with I created a sample web service.  Nothing special just a vanilla asmx web service hosted in IIS6 on Windows 2003 Standard Edition.  The web service is just a hello world style web service as shown in the below picture.  The only key feature is that the server side web method has a 30 second sleep in it and will trace out some information before and after the thread is set to sleep.      In the configuration for this web service there again is nothing special it's pretty much the most plain simple web service you could build. Client-Side To begin looking at what was happening with our example I created a number of different ways to consume the web service. SoapHttpClientProtocol Example I created a small application which would use a normal proxy generated to call the web service.  It would iterate around a loop and make calls using the begin/end methods so I can do this asynchronously.  I would do a loop of 20 calls with the ConnectionManager configuration section supporting only 5 concurrent connections to the server.     <connectionManagement> <remove address="*"/> <add address = "*" maxconnection = "12" /> <add address = "http://<ServerName>" maxconnection = "5" />                         </connectionManagement> </system.net>     The below picture shows an example of the service calling code, key points are: I have configured the timeout of 40 seconds for the proxy I am using the asynchronous methods on the proxy to call the web service         The Test I would run the client and execute 21 calls to the web service.   The Results  Below is the client side trace showing what's happening on the client. In the below diagram is the web service side trace showing what's happening on the server Some observations on the results are: All of the calls were successful from the clients perspective You could see the next call starting on the server as soon as the previous one had completed Calls took significantly longer than 40 seconds from the start of our call to the return. In fact call 20 took 2 minutes and 30 seconds from the perspective of my code to execute even though I had set the timeout to 40 seconds     WSE 2 Sample In the second example I used the exact same code to call the web service again with a single exception that I modified the web service proxy to derive from WebServiceClient protocol which is part of WSE 2 (using SP3).  The below picture shows the basic code and the key points are: I have configured the timeout of 40 seconds for the proxy I am using the asynchronous methods on the proxy to call the web service        The Test This test would execute 21 calls from the client to the web service.   The Results  The below trace is from the client side: The below trace is from the server side:   Some observations on the trace results for this scenario are: With call 4 if you look at the server side trace it did not start executing on the server for a number of seconds after the other 4 initial calls which were accepted by the server. I re-ran the test and this happened a couple of times and not on most others so at this point I'm just putting this down to something unexpected happening on the development machine and we will leave this observation out of scope of this article. You can see that the client side trace statement executed almost immediately in all cases All calls after the initial few calls would timeout On the client side the calls that did timeout; timed out in a longer duration than the 40 seconds we set as the timeout You can see that as calls were completing on the server the next calls were starting to come through The calls that timed out on the client did actually connect to the server and their server side execution completed successfully     Elaboration on the findings Based on the above observations I have drawn the below sequence diagram to illustrate conceptually what is happening.  Everything except the final web service object is on the client side of the call. In the diagram below I've put two notes on the Web Service Proxy to show the two different places where the different base classes seem to start their timeout counters. From the earlier samples we can work out that the timeout counter for the WSE web service proxy starts before the one for the SoapHttpClientProtocol proxy and the WSE one includes the time to get a connection from the pool; whereas the Soap proxy timeout just covers the method execution. One interesting observation is if we rerun the above sample and increase the number of calls from 21 to 100,000 then for the WSE sample we will see a similar pattern where everything after the first few calls will timeout on the client as soon as it makes a connection to the server whereas the soap proxy will happily plug away and process all of the calls without a single timeout. I have actually set the sample running overnight and this did happen. At this point you are probably thinking the same thoughts I was at the time about the differences in behaviour and which is right and why are they different? I'm not sure there is a definitive answer to this in the documentation, or at least not that I could find! I think you just have to consider that they are different and they could have different effects depending on your messaging solution. In lots of situations this is just not an issue as your concurrent requests doesn't get to the situation where you end up throttling the web service calls on the client side, however this is definitely more common with an integration broker such as BizTalk where you often have high throughput requirements.  Some of the considerations you should make Based on this behaviour you should be aware of the following: In a .net application if you are making lots of concurrent web service calls from an application in an asynchronous manner your user may thing they are experiencing poor performance but you think your web service is working well. The problem could be that the client will have a default of 2 connections to remote servers so you should bear this in mind When you are developing a BizTalk solution or a .net solution with the WSE 2 stack you may experience timeouts under load and throttling the number of connections using the max connections element in the configuration file will not help you For an application using WSE2 or SoapHttpClientProtocol an expired timeout will not throw an error until after a connection to the server has been made so you should consider this in your transaction and durability patterns     Our Work Around In the short term for our specific scenario we know that we can handle this by just increasing our timeout value.  There is only a specific small window when we get lots of concurrent traffic that causes this scenario so we should be able to increase the timeout to take into consideration the additional client side wait, and on the odd occasion where we do get a timeout the BizTalk send port retry will handle this. What was causing our original problem was that for that short window we were getting a lot of retries which significantly increased the load on our send servers and highlighted the issue.  Longer Term Solution As a longer term solution this really gives us more ammunition to argue a migration to WCF. The application we are calling has some factors which limit the protocols we can use but with WCF we would have more control on the various timeout options because in WCF you can configure specific parts of the timeout. Summary I've had this blog post on my to do list for ages but hopefully it will be useful to some people to just understand this behaviour and to possibly help you with some performance issues you may have. I do not believe there is too much in the way of documentation particularly around WSE2 and ASMX in this area so again another bit of ammunition for migrating to WCF. I'll try to do a follow up post with the sample for WCF to show how this changes things.

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  • adding tabs to tabcontrol from inside usercontrol

    - by Jakob
    How can I add tabs to a tabcontrol that exists in one usercontrol from another usercontrol that is contained within a tab itself?? Can I do it without passing in the tabcontrol as a parameter in the constructor, perhaps via some static global method? I've tried public static ObservableTabCollection FindCollectionFromUC(this DependencyObject depObject) { bool loop = true; var parent = (VisualTreeHelper.GetParent(depObject) as FrameworkElement); while (loop) { if (parent.GetType() is TabControl) { loop = false; return ((ObservableTabCollection)((TabControl)parent).ItemsSource); } } return null; } but this is just an infinite loop

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  • Contracts vs Exceptions

    - by devoured elysium
    Let's assume I have the following code: public class MainClass { public static void main(String[] args) { System.out.println(sumNumbers(10, 10)); } //@requires a >= 10; //@ensures \result < 0; public static int sumNumbers(int a, int b) { return a+b; } } I can make 2 things here: Use Code Contracts (in this case, what is in comments). When sumNumbers is run and a < 10, it will throw immediatly an exception (although it doesn't seem to be very descriptive): Exception in thread "main" org.jmlspecs.jmlrac.runtime.JMLInternalNormalPostconditionError: by method MainClass.sumNumbers at MainClass.sumNumbers(MainClass.java:500) at MainClass.internal$main(MainClass.java:9) at MainClass.main(MainClass.java:286) or... Throw an exception. The exception can be as descriptive as I want. I'd also to check in the end of the function to see whenever the post conditions are true or not. Which would you use here and why?

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  • Automatically create bug resolution task using the TFS 2010 API

    - by Bob Hardister
    My customer requires bug resolution to be approved and tracked.  To minimize the overhead for developers I implemented a TFS 2010 server-side plug-in to automatically create a child resolution task for the bug when the “CCB” field is set to approved. The CCB field is a custom field.  I also added the story points field to the bug WIT for sizing purposes. Redundant tasks will not be created unless the bug title is changed or the prior task is closed. The program writes an audit trail to a log file visible in the TFS Admin Console Log view. Here’s the code. BugAutoTask.cs /* SPECIFICATION * When the CCB field on the bug is set to approved, create a child task where the task: * name = Resolve bug [ID] - [Title of bug] * assigned to = same as assigned to field on the bug * same area path * same iteration path * activity = Bug Resolution * original estimate = bug points * * The source code is used to build a dll (Ows.TeamFoundation.BugAutoTaskCreation.PlugIns.dll), * which needs to be copied to * C:\Program Files\Microsoft Team Foundation Server 2010\Application Tier\Web Services\bin\Plugins * on ALL TFS application-tier servers. * * Author: Bob Hardister. */ using System; using System.Collections.Generic; using System.IO; using System.Xml; using System.Text; using System.Diagnostics; using System.Linq; using Microsoft.TeamFoundation.Common; using Microsoft.TeamFoundation.Framework.Server; using Microsoft.TeamFoundation.WorkItemTracking.Client; using Microsoft.TeamFoundation.WorkItemTracking.Server; using Microsoft.TeamFoundation.Client; using System.Collections; namespace BugAutoTaskCreation { public class BugAutoTask : ISubscriber { public EventNotificationStatus ProcessEvent(TeamFoundationRequestContext requestContext, NotificationType notificationType, object notificationEventArgs, out int statusCode, out string statusMessage, out ExceptionPropertyCollection properties) { statusCode = 0; properties = null; statusMessage = String.Empty; // Error message for for tracing last code executed and optional fields string lastStep = "No field values found or set "; try { if ((notificationType == NotificationType.Notification) && (notificationEventArgs.GetType() == typeof(WorkItemChangedEvent))) { WorkItemChangedEvent workItemChange = (WorkItemChangedEvent)notificationEventArgs; // see ConnectToTFS() method below to select which TFS instance/collection // to connect to TfsTeamProjectCollection tfs = ConnectToTFS(); WorkItemStore wiStore = tfs.GetService<WorkItemStore>(); lastStep = lastStep + ": connection to TFS successful "; // Get the work item that was just changed by the user. WorkItem witem = wiStore.GetWorkItem(workItemChange.CoreFields.IntegerFields[0].NewValue); lastStep = lastStep + ": retrieved changed work item, ID:" + witem.Id + " "; // Filter for Bug work items only if (witem.Type.Name == "Bug") { // DEBUG lastStep = lastStep + ": changed work item is a bug "; // Filter for CCB (i.e. Baseline Status) field set to approved only bool BaselineStatusChange = false; if (workItemChange.ChangedFields != null) { ProcessBugRevision(ref lastStep, workItemChange, wiStore, ref witem, ref BaselineStatusChange); } } } } catch (Exception e) { Trace.WriteLine(e.Message); Logger log = new Logger(); log.WriteLineToLog(MsgLevel.Error, "Application error: " + lastStep + " - " + e.Message + " - " + e.InnerException); } statusCode = 1; statusMessage = "Bug Auto Task Evaluation Completed"; properties = null; return EventNotificationStatus.ActionApproved; } // PRIVATE METHODS private static void ProcessBugRevision(ref string lastStep, WorkItemChangedEvent workItemChange, WorkItemStore wiStore, ref WorkItem witem, ref bool BaselineStatusChange) { foreach (StringField field in workItemChange.ChangedFields.StringFields) { // DEBUG lastStep = lastStep + ": last changed field is - " + field.Name + " "; if (field.Name == "Baseline Status") { lastStep = lastStep + ": retrieved bug baseline status field value, bug ID:" + witem.Id + " "; BaselineStatusChange = (field.NewValue != field.OldValue); if ((BaselineStatusChange) && (field.NewValue == "Approved")) { // Instanciate logger Logger log = new Logger(); // *** Create resolution task for this bug *** // ******************************************* // Get the team project and selected field values of the bug work item Project teamProject = witem.Project; int bugID = witem.Id; string bugTitle = witem.Fields["System.Title"].Value.ToString(); string bugAssignedTo = witem.Fields["System.AssignedTo"].Value.ToString(); string bugAreaPath = witem.Fields["System.AreaPath"].Value.ToString(); string bugIterationPath = witem.Fields["System.IterationPath"].Value.ToString(); string bugChangedBy = witem.Fields["System.ChangedBy"].OriginalValue.ToString(); string bugTeamProject = witem.Project.Name; lastStep = lastStep + ": all mandatory bug field values found "; // Optional fields Field bugPoints = witem.Fields["Microsoft.VSTS.Scheduling.StoryPoints"]; if (bugPoints.Value != null) { lastStep = lastStep + ": all mandatory and optional bug field values found "; } // Initialize child resolution task title string childTaskTitle = "Resolve bug " + bugID + " - " + bugTitle; // At this point I can check if a resolution task (of the same name) // for the bug already exist // If so, do not create a new resolution task bool createResolutionTask = true; WorkItem parentBug = wiStore.GetWorkItem(bugID); WorkItemLinkCollection links = parentBug.WorkItemLinks; foreach (WorkItemLink wil in links) { if (wil.LinkTypeEnd.Name == "Child") { WorkItem childTask = wiStore.GetWorkItem(wil.TargetId); if ((childTask.Title == childTaskTitle) && (childTask.State != "Closed")) { createResolutionTask = false; log.WriteLineToLog(MsgLevel.Info, "Team project " + bugTeamProject + ": " + bugChangedBy + " - set the CCB field to \"Approved\" for bug, ID: " + bugID + ". Task not created as open one of the same name already exist, ID:" + childTask.Id); } } } if (createResolutionTask) { // Define the work item type of the new work item WorkItemTypeCollection workItemTypes = wiStore.Projects[teamProject.Name].WorkItemTypes; WorkItemType wiType = workItemTypes["Task"]; // Setup the new task and assign field values witem = new WorkItem(wiType); witem.Fields["System.Title"].Value = "Resolve bug " + bugID + " - " + bugTitle; witem.Fields["System.AssignedTo"].Value = bugAssignedTo; witem.Fields["System.AreaPath"].Value = bugAreaPath; witem.Fields["System.IterationPath"].Value = bugIterationPath; witem.Fields["Microsoft.VSTS.Common.Activity"].Value = "Bug Resolution"; lastStep = lastStep + ": all mandatory task field values set "; // Optional fields if (bugPoints.Value != null) { witem.Fields["Microsoft.VSTS.Scheduling.OriginalEstimate"].Value = bugPoints.Value; lastStep = lastStep + ": all mandatory and optional task field values set "; } // Check for validation errors before saving the new task and linking it to the bug ArrayList validationErrors = witem.Validate(); if (validationErrors.Count == 0) { witem.Save(); // Link the new task (child) to the bug (parent) var linkType = wiStore.WorkItemLinkTypes[CoreLinkTypeReferenceNames.Hierarchy]; // Fetch the work items to be linked var parentWorkItem = wiStore.GetWorkItem(bugID); int taskID = witem.Id; var childWorkItem = wiStore.GetWorkItem(taskID); // Add a new link to the parent relating the child and save it parentWorkItem.Links.Add(new WorkItemLink(linkType.ForwardEnd, childWorkItem.Id)); parentWorkItem.Save(); log.WriteLineToLog(MsgLevel.Info, "Team project " + bugTeamProject + ": " + bugChangedBy + " - set the CCB field to \"Approved\" for bug, ID:" + bugID + ", which automatically created child resolution task, ID:" + taskID); } else { log.WriteLineToLog(MsgLevel.Error, "Error in creating bug resolution child task for bug ID:" + bugID); foreach (Field taskField in validationErrors) { log.WriteLineToLog(MsgLevel.Error, " - Validation Error in task field: " + taskField.ReferenceName); } } } } } } } private TfsTeamProjectCollection ConnectToTFS() { // Connect to TFS string tfsUri = string.Empty; // Production TFS instance production collection tfsUri = @"xxxx"; // Production TFS instance admin collection //tfsUri = @"xxxxx"; // Local TFS testing instance default collection //tfsUri = @"xxxxx"; TfsTeamProjectCollection tfs = new TfsTeamProjectCollection(new System.Uri(tfsUri)); tfs.EnsureAuthenticated(); return tfs; } // HELPERS public string Name { get { return "Bug Auto Task Creation Event Handler"; } } public SubscriberPriority Priority { get { return SubscriberPriority.Normal; } } public enum MsgLevel { Info, Warning, Error }; public Type[] SubscribedTypes() { return new Type[1] { typeof(WorkItemChangedEvent) }; } } } Logger.cs using System; using System.Collections.Generic; using System.IO; using System.Linq; using System.Text; using System.Windows.Forms; namespace BugAutoTaskCreation { class Logger { // fields private string _ApplicationDirectory = @"C:\ProgramData\Microsoft\Team Foundation\Server Configuration\Logs"; private string _LogFileName = @"\CFG_ACCT_AT_OWS_BugAutoTaskCreation.log"; private string _LogFile; private string _LogTimestamp = DateTime.Now.ToString("MM/dd/yyyy HH:mm:ss"); private string _MsgLevelText = string.Empty; // default constructor public Logger() { // check for a prior log file FileInfo logFile = new FileInfo(_ApplicationDirectory + _LogFileName); if (!logFile.Exists) { CreateNewLogFile(ref logFile); } } // properties public string ApplicationDirectory { get { return _ApplicationDirectory; } set { _ApplicationDirectory = value; } } public string LogFile { get { _LogFile = _ApplicationDirectory + _LogFileName; return _LogFile; } set { _LogFile = value; } } // PUBLIC METHODS public void WriteLineToLog(BugAutoTask.MsgLevel msgLevel, string logRecord) { try { // set msgLevel text if (msgLevel == BugAutoTask.MsgLevel.Info) { _MsgLevelText = "[Info @" + MsgTimeStamp() + "] "; } else if (msgLevel == BugAutoTask.MsgLevel.Warning) { _MsgLevelText = "[Warning @" + MsgTimeStamp() + "] "; } else if (msgLevel == BugAutoTask.MsgLevel.Error) { _MsgLevelText = "[Error @" + MsgTimeStamp() + "] "; } else { _MsgLevelText = "[Error: unsupported message level @" + MsgTimeStamp() + "] "; } // write a line to the log file StreamWriter logFile = new StreamWriter(_ApplicationDirectory + _LogFileName, true); logFile.WriteLine(_MsgLevelText + logRecord); logFile.Close(); } catch (Exception) { throw; } } // PRIVATE METHODS private void CreateNewLogFile(ref FileInfo logFile) { try { string logFilePath = logFile.FullName; // write the log file header _MsgLevelText = "[Info @" + MsgTimeStamp() + "] "; string cpu = string.Empty; if (Environment.Is64BitOperatingSystem) { cpu = " (x64)"; } StreamWriter newLog = new StreamWriter(logFilePath, false); newLog.Flush(); newLog.WriteLine(_MsgLevelText + "===================================================================="); newLog.WriteLine(_MsgLevelText + "Team Foundation Server Administration Log"); newLog.WriteLine(_MsgLevelText + "Version : " + "1.0.0 Author: Bob Hardister"); newLog.WriteLine(_MsgLevelText + "DateTime : " + _LogTimestamp); newLog.WriteLine(_MsgLevelText + "Type : " + "OWS Custom TFS API Plug-in"); newLog.WriteLine(_MsgLevelText + "Activity : " + "Bug Auto Task Creation for CCB Approved Bugs"); newLog.WriteLine(_MsgLevelText + "Area : " + "Build Explorer"); newLog.WriteLine(_MsgLevelText + "Assembly : " + "Ows.TeamFoundation.BugAutoTaskCreation.PlugIns.dll"); newLog.WriteLine(_MsgLevelText + "Location : " + @"C:\Program Files\Microsoft Team Foundation Server 2010\Application Tier\Web Services\bin\Plugins"); newLog.WriteLine(_MsgLevelText + "User : " + Environment.UserDomainName + @"\" + Environment.UserName); newLog.WriteLine(_MsgLevelText + "Machine : " + Environment.MachineName); newLog.WriteLine(_MsgLevelText + "System : " + Environment.OSVersion + cpu); newLog.WriteLine(_MsgLevelText + "===================================================================="); newLog.WriteLine(_MsgLevelText); newLog.Close(); } catch (Exception) { throw; } } private string MsgTimeStamp() { string msgTimestamp = string.Empty; return msgTimestamp = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss:fff"); } } }

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  • How to make a UserControl with a custom DefaultBackColor?

    - by Blorgbeard
    When I right-click on my custom UserControl's BackColor property in the property-grid, then click Reset, I would like the BackColor property to change to (for example) Color.LightGreen, and the property value to appear un-bolded, to indicate that it is the default value. Currently, I know I can do this: public override void ResetBackColor() { BackColor = Color.LightGreen; } Which works as far as setting it to LightGreen on reset. But it still appears bolded in the property-grid, indicating that the current value is not the default. I notice that the Control class has a static read-only property, DefaultBackColor. Unfortunately, since it's static, I cannot override it. Is there some way to get all the functionality I want?

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  • How can I limit access to a particular class to one caller at a time in a web service?

    - by MusiGenesis
    I have a web service method in which I create a particular type of object, use it for a few seconds, and then dispose it. Because of problems arising from multiple threads creating and using instances of this class at the same time, I need to restrict the method so that only one caller at a time ever has one of these objects. To do this, I am creating a private static object: private static object _lock = new object(); ... and then inside the web service method I do this around the critical code: lock (_lock) { using (DangerousObject do = new DangerousObject()) { do.MakeABigMess(); do.CleanItUp(); } } I'm not sure this is working, though. Do I have this right? Will this code ensure that only one instance of DangerousObject is instantiated and in use at a time?

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  • Test-Driven Development Problem

    - by Zeck
    Hi guys, I'm newbie to Java EE 6 and i'm trying to develop very simple JAX-RS application. RESTfull web service working fine. However when I ran my test application, I got the following. What have I done wrong? Or am i forget any configuration? Of course i'm create a JNDI and i'm using Netbeans 6.8 IDE. In finally, thank you for any advise. My Entity: @Entity @Table(name = "BOOK") @NamedQueries({ @NamedQuery(name = "Book.findAll", query = "SELECT b FROM Book b"), @NamedQuery(name = "Book.findById", query = "SELECT b FROM Book b WHERE b.id = :id"), @NamedQuery(name = "Book.findByTitle", query = "SELECT b FROM Book b WHERE b.title = :title"), @NamedQuery(name = "Book.findByDescription", query = "SELECT b FROM Book b WHERE b.description = :description"), @NamedQuery(name = "Book.findByPrice", query = "SELECT b FROM Book b WHERE b.price = :price"), @NamedQuery(name = "Book.findByNumberofpage", query = "SELECT b FROM Book b WHERE b.numberofpage = :numberofpage")}) public class Book implements Serializable { private static final long serialVersionUID = 1L; @Id @Basic(optional = false) @Column(name = "ID") private Integer id; @Basic(optional = false) @Column(name = "TITLE") private String title; @Basic(optional = false) @Column(name = "DESCRIPTION") private String description; @Basic(optional = false) @Column(name = "PRICE") private double price; @Basic(optional = false) @Column(name = "NUMBEROFPAGE") private int numberofpage; public Book() { } public Book(Integer id) { this.id = id; } public Book(Integer id, String title, String description, double price, int numberofpage) { this.id = id; this.title = title; this.description = description; this.price = price; this.numberofpage = numberofpage; } public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getTitle() { return title; } public void setTitle(String title) { this.title = title; } public String getDescription() { return description; } public void setDescription(String description) { this.description = description; } public double getPrice() { return price; } public void setPrice(double price) { this.price = price; } public int getNumberofpage() { return numberofpage; } public void setNumberofpage(int numberofpage) { this.numberofpage = numberofpage; } @Override public int hashCode() { int hash = 0; hash += (id != null ? id.hashCode() : 0); return hash; } @Override public boolean equals(Object object) { // TODO: Warning - this method won't work in the case the id fields are not set if (!(object instanceof Book)) { return false; } Book other = (Book) object; if ((this.id == null && other.id != null) || (this.id != null && !this.id.equals(other.id))) { return false; } return true; } @Override public String toString() { return "com.entity.Book[id=" + id + "]"; } } My Junit test class: public class BookTest { private static EntityManager em; private static EntityManagerFactory emf; public BookTest() { } @BeforeClass public static void setUpClass() throws Exception { emf = Persistence.createEntityManagerFactory("E01R01PU"); em = emf.createEntityManager(); } @AfterClass public static void tearDownClass() throws Exception { em.close(); emf.close(); } @Test public void createBook() { Book book = new Book(); book.setId(1); book.setDescription("Mastering the Behavior Driven Development with Ruby on Rails"); book.setTitle("Mastering the BDD"); book.setPrice(25.9f); book.setNumberofpage(1029); em.persist(book); assertNotNull("ID should not be null", book.getId()); } } My persistence.xml jta-data-sourceBookstoreJNDI And exception is: May 7, 2009 11:10:37 AM org.hibernate.validator.util.Version INFO: Hibernate Validator bean-validator-3.0-JBoss-4.0.2 May 7, 2009 11:10:37 AM org.hibernate.validator.engine.resolver.DefaultTraversableResolver detectJPA INFO: Instantiated an instance of org.hibernate.validator.engine.resolver.JPATraversableResolver. [EL Info]: 2009-05-07 11:10:37.531--ServerSession(13671123)--EclipseLink, version: Eclipse Persistence Services - 2.0.0.v20091127-r5931 May 7, 2009 11:10:40 AM com.sun.enterprise.transaction.JavaEETransactionManagerSimplified initDelegates INFO: Using com.sun.enterprise.transaction.jts.JavaEETransactionManagerJTSDelegate as the delegate May 7, 2009 11:10:43 AM com.sun.enterprise.connectors.ActiveRAFactory createActiveResourceAdapter SEVERE: rardeployment.class_not_found May 7, 2009 11:10:43 AM com.sun.enterprise.connectors.ActiveRAFactory createActiveResourceAdapter SEVERE: com.sun.appserv.connectors.internal.api.ConnectorRuntimeException: Error in creating active RAR at com.sun.enterprise.connectors.ActiveRAFactory.createActiveResourceAdapter(ActiveRAFactory.java:104) at com.sun.enterprise.connectors.service.ResourceAdapterAdminServiceImpl.createActiveResourceAdapter(ResourceAdapterAdminServiceImpl.java:216) at com.sun.enterprise.connectors.ConnectorRuntime.createActiveResourceAdapter(ConnectorRuntime.java:352) at com.sun.enterprise.resource.naming.ConnectorObjectFactory.getObjectInstance(ConnectorObjectFactory.java:106) at javax.naming.spi.NamingManager.getObjectInstance(NamingManager.java:304) at com.sun.enterprise.naming.impl.SerialContext.getObjectInstance(SerialContext.java:472) at com.sun.enterprise.naming.impl.SerialContext.lookup(SerialContext.java:437) at com.sun.enterprise.naming.impl.SerialContext.lookup(SerialContext.java:569) at javax.naming.InitialContext.lookup(InitialContext.java:396) at org.eclipse.persistence.sessions.JNDIConnector.connect(JNDIConnector.java:110) at org.eclipse.persistence.sessions.JNDIConnector.connect(JNDIConnector.java:94) at org.eclipse.persistence.sessions.DatasourceLogin.connectToDatasource(DatasourceLogin.java:162) at org.eclipse.persistence.internal.sessions.DatabaseSessionImpl.loginAndDetectDatasource(DatabaseSessionImpl.java:584) at org.eclipse.persistence.internal.jpa.EntityManagerFactoryProvider.login(EntityManagerFactoryProvider.java:228) at org.eclipse.persistence.internal.jpa.EntityManagerSetupImpl.deploy(EntityManagerSetupImpl.java:368) at org.eclipse.persistence.internal.jpa.EntityManagerFactoryImpl.getServerSession(EntityManagerFactoryImpl.java:151) at org.eclipse.persistence.internal.jpa.EntityManagerFactoryImpl.createEntityManagerImpl(EntityManagerFactoryImpl.java:207) at org.eclipse.persistence.internal.jpa.EntityManagerFactoryImpl.createEntityManager(EntityManagerFactoryImpl.java:195) at com.entity.BookTest.setUpClass(BookTest.java:31) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41) at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:27) at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:31) at org.junit.runners.ParentRunner.run(ParentRunner.java:220) at junit.framework.JUnit4TestAdapter.run(JUnit4TestAdapter.java:39) at org.apache.tools.ant.taskdefs.optional.junit.JUnitTestRunner.run(JUnitTestRunner.java:515) at org.apache.tools.ant.taskdefs.optional.junit.JUnitTestRunner.launch(JUnitTestRunner.java:1031) at org.apache.tools.ant.taskdefs.optional.junit.JUnitTestRunner.main(JUnitTestRunner.java:888) Caused by: java.lang.ClassNotFoundException: com.sun.gjc.spi.ResourceAdapter at java.net.URLClassLoader$1.run(URLClassLoader.java:200) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:188) at java.lang.ClassLoader.loadClass(ClassLoader.java:306) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:276) at java.lang.ClassLoader.loadClass(ClassLoader.java:251) at com.sun.enterprise.connectors.ActiveRAFactory.createActiveResourceAdapter(ActiveRAFactory.java:96) ... 32 more [EL Severe]: 2009-05-07 11:10:43.937--ServerSession(13671123)--Local Exception Stack: Exception [EclipseLink-7060] (Eclipse Persistence Services - 2.0.0.v20091127-r5931): org.eclipse.persistence.exceptions.ValidationException Exception Description: Cannot acquire data source [BookstoreJNDI]. Internal Exception: javax.naming.NamingException: Lookup failed for 'BookstoreJNDI' in SerialContext ,orb'sInitialHost=localhost,orb'sInitialPort=3700 [Root exception is javax.naming.NamingException: Failed to look up ConnectorDescriptor from JNDI [Root exception is com.sun.appserv.connectors.internal.api.ConnectorRuntimeException: Error in creating active RAR]] at org.eclipse.persistence.exceptions.ValidationException.cannotAcquireDataSource(ValidationException.java:451) at org.eclipse.persistence.sessions.JNDIConnector.connect(JNDIConnector.java:116) at org.eclipse.persistence.sessions.JNDIConnector.connect(JNDIConnector.java:94) at org.eclipse.persistence.sessions.DatasourceLogin.connectToDatasource(DatasourceLogin.java:162) at org.eclipse.persistence.internal.sessions.DatabaseSessionImpl.loginAndDetectDatasource(DatabaseSessionImpl.java:584) at org.eclipse.persistence.internal.jpa.EntityManagerFactoryProvider.login(EntityManagerFactoryProvider.java:228) at org.eclipse.persistence.internal.jpa.EntityManagerSetupImpl.deploy(EntityManagerSetupImpl.java:368) at org.eclipse.persistence.internal.jpa.EntityManagerFactoryImpl.getServerSession(EntityManagerFactoryImpl.java:151) at org.eclipse.persistence.internal.jpa.EntityManagerFactoryImpl.createEntityManagerImpl(EntityManagerFactoryImpl.java:207) at org.eclipse.persistence.internal.jpa.EntityManagerFactoryImpl.createEntityManager(EntityManagerFactoryImpl.java:195) at com.entity.BookTest.setUpClass(BookTest.java:31) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41) at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:27) at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:31) at org.junit.runners.ParentRunner.run(ParentRunner.java:220) at junit.framework.JUnit4TestAdapter.run(JUnit4TestAdapter.java:39) at org.apache.tools.ant.taskdefs.optional.junit.JUnitTestRunner.run(JUnitTestRunner.java:515) at org.apache.tools.ant.taskdefs.optional.junit.JUnitTestRunner.launch(JUnitTestRunner.java:1031) at org.apache.tools.ant.taskdefs.optional.junit.JUnitTestRunner.main(JUnitTestRunner.java:888) Caused by: javax.naming.NamingException: Lookup failed for 'BookstoreJNDI' in SerialContext ,orb'sInitialHost=localhost,orb'sInitialPort=3700 [Root exception is javax.naming.NamingException: Failed to look up ConnectorDescriptor from JNDI [Root exception is com.sun.appserv.connectors.internal.api.ConnectorRuntimeException: Error in creating active RAR]] at com.sun.enterprise.naming.impl.SerialContext.lookup(SerialContext.java:442) at com.sun.enterprise.naming.impl.SerialContext.lookup(SerialContext.java:569) at javax.naming.InitialContext.lookup(InitialContext.java:396) at org.eclipse.persistence.sessions.JNDIConnector.connect(JNDIConnector.java:110) ... 23 more Caused by: javax.naming.NamingException: Failed to look up ConnectorDescriptor from JNDI [Root exception is com.sun.appserv.connectors.internal.api.ConnectorRuntimeException: Error in creating active RAR] at com.sun.enterprise.resource.naming.ConnectorObjectFactory.getObjectInstance(ConnectorObjectFactory.java:109) at javax.naming.spi.NamingManager.getObjectInstance(NamingManager.java:304) at com.sun.enterprise.naming.impl.SerialContext.getObjectInstance(SerialContext.java:472) at com.sun.enterprise.naming.impl.SerialContext.lookup(SerialContext.java:437) ... 26 more Caused by: com.sun.appserv.connectors.internal.api.ConnectorRuntimeException: Error in creating active RAR at com.sun.enterprise.connectors.ActiveRAFactory.createActiveResourceAdapter(ActiveRAFactory.java:104) at com.sun.enterprise.connectors.service.ResourceAdapterAdminServiceImpl.createActiveResourceAdapter(ResourceAdapterAdminServiceImpl.java:216) at com.sun.enterprise.connectors.ConnectorRuntime.createActiveResourceAdapter(ConnectorRuntime.java:352) at com.sun.enterprise.resource.naming.ConnectorObjectFactory.getObjectInstance(ConnectorObjectFactory.java:106) ... 29 more Caused by: java.lang.ClassNotFoundException: com.sun.gjc.spi.ResourceAdapter at java.net.URLClassLoader$1.run(URLClassLoader.java:200) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:188) at java.lang.ClassLoader.loadClass(ClassLoader.java:306) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:276) at java.lang.ClassLoader.loadClass(ClassLoader.java:251) at com.sun.enterprise.connectors.ActiveRAFactory.createActiveResourceAdapter(ActiveRAFactory.java:96) ... 32 more Exception Description: Cannot acquire data source [BookstoreJNDI]. Internal Exception: javax.naming.NamingException: Lookup failed for 'BookstoreJNDI' in SerialContext ,orb'sInitialHost=localhost,orb'sInitialPort=3700 [Root exception is javax.naming.NamingException: Failed to look up ConnectorDescriptor from JNDI [Root exception is com.sun.appserv.connectors.internal.api.ConnectorRuntimeException: Error in creating active RAR]])

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  • How to add correct cancellation when downloading a file with the example in the samples of the new P

    - by Mike
    Hello everybody, I have downloaded the last samples of the Parallel Programming team, and I don't succeed in adding correctly the possibility to cancel the download of a file. Here is the code I ended to have: var wreq = (HttpWebRequest)WebRequest.Create(uri); // Fire start event DownloadStarted(this, new DownloadStartedEventArgs(remoteFilePath)); long totalBytes = 0; wreq.DownloadDataInFileAsync(tmpLocalFile, cancellationTokenSource.Token, allowResume, totalBytesAction => { totalBytes = totalBytesAction; }, readBytes => { Log.Debug("Progression : {0} / {1} => {2}%", readBytes, totalBytes, 100 * (double)readBytes / totalBytes); DownloadProgress(this, new DownloadProgressEventArgs(remoteFilePath, readBytes, totalBytes, (int)(100 * readBytes / totalBytes))); }) .ContinueWith( (antecedent ) => { if (antecedent.IsFaulted) Log.Debug(antecedent.Exception.Message); //Fire end event SetEndDownload(antecedent.IsCanceled, antecedent.Exception, tmpLocalFile, 0); }, cancellationTokenSource.Token); I want to fire an end event after the download is finished, hence the ContinueWith. I slightly changed the code of the samples to add the CancellationToken and the 2 delegates to get the size of the file to download, and the progression of the download: return webRequest.GetResponseAsync() .ContinueWith(response => { if (totalBytesAction != null) totalBytesAction(response.Result.ContentLength); response.Result.GetResponseStream().WriteAllBytesAsync(filePath, ct, resumeDownload, progressAction).Wait(ct); }, ct); I had to add the call to the Wait function, because if I don't, the method exits and the end event is fired too early. Here are the modified method extensions (lot of code, apologies :p) public static Task WriteAllBytesAsync(this Stream stream, string filePath, CancellationToken ct, bool resumeDownload = false, Action<long> progressAction = null) { if (stream == null) throw new ArgumentNullException("stream"); // Copy from the source stream to the memory stream and return the copied data return stream.CopyStreamToFileAsync(filePath, ct, resumeDownload, progressAction); } public static Task CopyStreamToFileAsync(this Stream source, string destinationPath, CancellationToken ct, bool resumeDownload = false, Action<long> progressAction = null) { if (source == null) throw new ArgumentNullException("source"); if (destinationPath == null) throw new ArgumentNullException("destinationPath"); // Open the output file for writing var destinationStream = FileAsync.OpenWrite(destinationPath); // Copy the source to the destination stream, then close the output file. return CopyStreamToStreamAsync(source, destinationStream, ct, progressAction).ContinueWith(t => { var e = t.Exception; destinationStream.Close(); if (e != null) throw e; }, ct, TaskContinuationOptions.ExecuteSynchronously, TaskScheduler.Current); } public static Task CopyStreamToStreamAsync(this Stream source, Stream destination, CancellationToken ct, Action<long> progressAction = null) { if (source == null) throw new ArgumentNullException("source"); if (destination == null) throw new ArgumentNullException("destination"); return Task.Factory.Iterate(CopyStreamIterator(source, destination, ct, progressAction)); } private static IEnumerable<Task> CopyStreamIterator(Stream input, Stream output, CancellationToken ct, Action<long> progressAction = null) { // Create two buffers. One will be used for the current read operation and one for the current // write operation. We'll continually swap back and forth between them. byte[][] buffers = new byte[2][] { new byte[BUFFER_SIZE], new byte[BUFFER_SIZE] }; int filledBufferNum = 0; Task writeTask = null; int readBytes = 0; // Until there's no more data to be read or cancellation while (true) { ct.ThrowIfCancellationRequested(); // Read from the input asynchronously var readTask = input.ReadAsync(buffers[filledBufferNum], 0, buffers[filledBufferNum].Length); // If we have no pending write operations, just yield until the read operation has // completed. If we have both a pending read and a pending write, yield until both the read // and the write have completed. yield return writeTask == null ? readTask : Task.Factory.ContinueWhenAll(new[] { readTask, writeTask }, tasks => tasks.PropagateExceptions()); // If no data was read, nothing more to do. if (readTask.Result <= 0) break; readBytes += readTask.Result; if (progressAction != null) progressAction(readBytes); // Otherwise, write the written data out to the file writeTask = output.WriteAsync(buffers[filledBufferNum], 0, readTask.Result); // Swap buffers filledBufferNum ^= 1; } } So basically, at the end of the chain of called methods, I let the CancellationToken throw an OperationCanceledException if a Cancel has been requested. What I hoped was to get IsFaulted == true in the appealing code and to fire the end event with the canceled flags and the correct exception. But what I get is an unhandled exception on the line response.Result.GetResponseStream().WriteAllBytesAsync(filePath, ct, resumeDownload, progressAction).Wait(ct); telling me that I don't catch an AggregateException. I've tried various things, but I don't succeed to make the whole thing work properly. Does anyone of you have played enough with that library and may help me? Thanks in advance Mike

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  • The .NET ActiveX component with WPF content can't be loaded by non MFC app

    - by lonelyflyer
    I have a legacy delphi program and want to add some content implemented with WPF. So I encapsulate the WPF control with a .NET/ActiveX interop technology. That means something like: [ComRegisterFunction()] public static void RegisterClass(string key); [ComUnregisterFunction()] public static void UnregisterClass(string key); The activeX component is a WinForms User Control and the WPF materials are attached to an ElemenHost in this User Control. It works fine if the host app of this ActiveX is a MFC program even without /clr switch. But my legacy app is a delphi program, and it always throw a stackoverflow exception within the constructor of my WPF user control as the program be started. I have no clue, Google is no help. and it has puzzled me for days.

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  • Why unhandled exceptions are useful

    - by Simon Cooper
    It’s the bane of most programmers’ lives – an unhandled exception causes your application or webapp to crash, an ugly dialog gets displayed to the user, and they come complaining to you. Then, somehow, you need to figure out what went wrong. Hopefully, you’ve got a log file, or some other way of reporting unhandled exceptions (obligatory employer plug: SmartAssembly reports an application’s unhandled exceptions straight to you, along with the entire state of the stack and variables at that point). If not, you have to try and replicate it yourself, or do some psychic debugging to try and figure out what’s wrong. However, it’s good that the program crashed. Or, more precisely, it is correct behaviour. An unhandled exception in your application means that, somewhere in your code, there is an assumption that you made that is actually invalid. Coding assumptions Let me explain a bit more. Every method, every line of code you write, depends on implicit assumptions that you have made. Take this following simple method, that copies a collection to an array and includes an item if it isn’t in the collection already, using a supplied IEqualityComparer: public static T[] ToArrayWithItem( ICollection<T> coll, T obj, IEqualityComparer<T> comparer) { // check if the object is in collection already // using the supplied comparer foreach (var item in coll) { if (comparer.Equals(item, obj)) { // it's in the collection already // simply copy the collection to an array // and return it T[] array = new T[coll.Count]; coll.CopyTo(array, 0); return array; } } // not in the collection // copy coll to an array, and add obj to it // then return it T[] array = new T[coll.Count+1]; coll.CopyTo(array, 0); array[array.Length-1] = obj; return array; } What’s all the assumptions made by this fairly simple bit of code? coll is never null comparer is never null coll.CopyTo(array, 0) will copy all the items in the collection into the array, in the order defined for the collection, starting at the first item in the array. The enumerator for coll returns all the items in the collection, in the order defined for the collection comparer.Equals returns true if the items are equal (for whatever definition of ‘equal’ the comparer uses), false otherwise comparer.Equals, coll.CopyTo, and the coll enumerator will never throw an exception or hang for any possible input and any possible values of T coll will have less than 4 billion items in it (this is a built-in limit of the CLR) array won’t be more than 2GB, both on 32 and 64-bit systems, for any possible values of T (again, a limit of the CLR) There are no threads that will modify coll while this method is running and, more esoterically: The C# compiler will compile this code to IL according to the C# specification The CLR and JIT compiler will produce machine code to execute the IL on the user’s computer The computer will execute the machine code correctly That’s a lot of assumptions. Now, it could be that all these assumptions are valid for the situations this method is called. But if this does crash out with an exception, or crash later on, then that shows one of the assumptions has been invalidated somehow. An unhandled exception shows that your code is running in a situation which you did not anticipate, and there is something about how your code runs that you do not understand. Debugging the problem is the process of learning more about the new situation and how your code interacts with it. When you understand the problem, the solution is (usually) obvious. The solution may be a one-line fix, the rewrite of a method or class, or a large-scale refactoring of the codebase, but whatever it is, the fix for the crash will incorporate the new information you’ve gained about your own code, along with the modified assumptions. When code is running with an assumption or invariant it depended on broken, then the result is ‘undefined behaviour’. Anything can happen, up to and including formatting the entire disk or making the user’s computer sentient and start doing a good impression of Skynet. You might think that those can’t happen, but at Halting problem levels of generality, as soon as an assumption the code depended on is broken, the program can do anything. That is why it’s important to fail-fast and stop the program as soon as an invariant is broken, to minimise the damage that is done. What does this mean in practice? To start with, document and check your assumptions. As with most things, there is a level of judgement required. How you check and document your assumptions depends on how the code is used (that’s some more assumptions you’ve made), how likely it is a method will be passed invalid arguments or called in an invalid state, how likely it is the assumptions will be broken, how expensive it is to check the assumptions, and how bad things are likely to get if the assumptions are broken. Now, some assumptions you can assume unless proven otherwise. You can safely assume the C# compiler, CLR, and computer all run the method correctly, unless you have evidence of a compiler, CLR or processor bug. You can also assume that interface implementations work the way you expect them to; implementing an interface is more than simply declaring methods with certain signatures in your type. The behaviour of those methods, and how they work, is part of the interface contract as well. For example, for members of a public API, it is very important to document your assumptions and check your state before running the bulk of the method, throwing ArgumentException, ArgumentNullException, InvalidOperationException, or another exception type as appropriate if the input or state is wrong. For internal and private methods, it is less important. If a private method expects collection items in a certain order, then you don’t necessarily need to explicitly check it in code, but you can add comments or documentation specifying what state you expect the collection to be in at a certain point. That way, anyone debugging your code can immediately see what’s wrong if this does ever become an issue. You can also use DEBUG preprocessor blocks and Debug.Assert to document and check your assumptions without incurring a performance hit in release builds. On my coding soapbox… A few pet peeves of mine around assumptions. Firstly, catch-all try blocks: try { ... } catch { } A catch-all hides exceptions generated by broken assumptions, and lets the program carry on in an unknown state. Later, an exception is likely to be generated due to further broken assumptions due to the unknown state, causing difficulties when debugging as the catch-all has hidden the original problem. It’s much better to let the program crash straight away, so you know where the problem is. You should only use a catch-all if you are sure that any exception generated in the try block is safe to ignore. That’s a pretty big ask! Secondly, using as when you should be casting. Doing this: (obj as IFoo).Method(); or this: IFoo foo = obj as IFoo; ... foo.Method(); when you should be doing this: ((IFoo)obj).Method(); or this: IFoo foo = (IFoo)obj; ... foo.Method(); There’s an assumption here that obj will always implement IFoo. If it doesn’t, then by using as instead of a cast you’ve turned an obvious InvalidCastException at the point of the cast that will probably tell you what type obj actually is, into a non-obvious NullReferenceException at some later point that gives you no information at all. If you believe obj is always an IFoo, then say so in code! Let it fail-fast if not, then it’s far easier to figure out what’s wrong. Thirdly, document your assumptions. If an algorithm depends on a non-trivial relationship between several objects or variables, then say so. A single-line comment will do. Don’t leave it up to whoever’s debugging your code after you to figure it out. Conclusion It’s better to crash out and fail-fast when an assumption is broken. If it doesn’t, then there’s likely to be further crashes along the way that hide the original problem. Or, even worse, your program will be running in an undefined state, where anything can happen. Unhandled exceptions aren’t good per-se, but they give you some very useful information about your code that you didn’t know before. And that can only be a good thing.

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  • Is this a good way to manage initializations of COM?

    - by BillyONeal
    Hello everyone :) I'm very new to anything involving Component Object Model, and I'm wondering if this method of managing calls to CoInitalize/CoUninitalize makes sense: COM.hpp: #pragma once namespace WindowsAPI { namespace ComponentObjectModel { class COM { COM(); ~COM(); public: static void Setup(); }; }} COM.cpp: #include <Windows.h> #include "COM.hpp" namespace WindowsAPI { namespace ComponentObjectModel { COM::COM() { if (CoInitializeEx(NULL, COINIT_APARTMENTTHREADED) != S_OK) throw std::runtime_error("Couldn't start COM!"); } COM::~COM() { CoUninitialize(); } void COM::Setup() { static COM instance; } }} Then any component that needs COM just calls COM::Setup() and forgets about it. Does this make sense or am I breaking any "rules" of COM?

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  • Why can final object be modified?

    - by Matt McCormick
    I came across the following code in a code base I am working on: public final class ConfigurationService { private static final ConfigurationService INSTANCE = new ConfigurationService(); private List providers; private ConfigurationService() { providers = new ArrayList(); } public static void addProvider(ConfigurationProvider provider) { INSTANCE.providers.add(provider); } ... INSTANCE is declared as final. Why can objects be added to INSTANCE? Shouldn't that invalidate the use of final. (It doesn't). I'm assuming the answer has to do something with pointers and memory but would like to know for sure.

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