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• N-tier Repository POCOs - Aggregates?

  - by Sam

  Assume the following simple POCOs, Country and State: public partial class Country { public Country() { States = new List<State>(); } public virtual int CountryId { get; set; } public virtual string Name { get; set; } public virtual string CountryCode { get; set; } public virtual ICollection<State> States { get; set; } } public partial class State { public virtual int StateId { get; set; } public virtual int CountryId { get; set; } public virtual Country Country { get; set; } public virtual string Name { get; set; } public virtual string Abbreviation { get; set; } } Now assume I have a simple respository that looks something like this: public partial class CountryRepository : IDisposable { protected internal IDatabase _db; public CountryRepository() { _db = new Database(System.Configuration.ConfigurationManager.AppSettings["DbConnName"]); } public IEnumerable<Country> GetAll() { return _db.Query<Country>("SELECT * FROM Countries ORDER BY Name", null); } public Country Get(object id) { return _db.SingleById(id); } public void Add(Country c) { _db.Insert(c); } /* ...And So On... */ } Typically in my UI I do not display all of the children (states), but I do display an aggregate count. So my country list view model might look like this: public partial class CountryListVM { [Key] public int CountryId { get; set; } public string Name { get; set; } public string CountryCode { get; set; } public int StateCount { get; set; } } When I'm using the underlying data provider (Entity Framework, NHibernate, PetaPoco, etc) directly in my UI layer, I can easily do something like this: IList<CountryListVM> list = db.Countries .OrderBy(c => c.Name) .Select(c => new CountryListVM() { CountryId = c.CountryId, Name = c.Name, CountryCode = c.CountryCode, StateCount = c.States.Count }) .ToList(); But when I'm using a repository or service pattern, I abstract away direct access to the data layer. It seems as though my options are to: Return the Country with a populated States collection, then map over in the UI layer. The downside to this approach is that I'm returning a lot more data than is actually needed. -or- Put all my view models into my Common dll library (as opposed to having them in the Models directory in my MVC app) and expand my repository to return specific view models instead of just the domain pocos. The downside to this approach is that I'm leaking UI specific stuff (MVC data validation annotations) into my previously clean POCOs. -or- Are there other options? How are you handling these types of things?

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• How perform USort() on an Array of Objects class definition as a method?

  - by user558724

  class Contact{ public $name; public $bgcolor; public $lgcolor; public $email; public $element; public function __construct($name, $bgcolor, $lgcolor, $email, $element) { $this->name = $name; $this->bgcolor = $bgcolor; $this->lgcolor = $lgcolor; $this->email = $email; $this->element = $element; } public static function sortByName(Contact $p1, Contact $p2) { return strcmp($p1->name, $p2->name); } } class ContactList implements Iterator, ArrayAccess { protected $_label; protected $_contacts = array(); public function __construct($label) { $this->_label = $label; } public function getLabel() { return $this->_label; } public function addContact(Contact $contact) { $this->_contacts[] = $contact; } public function current() { return current($this->_contacts); } public function key() { return key($this->_contacts); } public function next() { return next($this->_contacts); } public function rewind() { return reset($this->_contacts); } public function valid() { return current($this->_contacts); } public function offsetGet($offset) { return $this->_contacts[$offset]; } public function offsetSet($offset, $data) { if (!$data instanceof Contact) throw new InvalidArgumentException('Only Contact objects allowed in a ContactList'); if ($offset == '') { $this->_contacts[] = $data; } else { $this->_contacts[$offset] = $data; } } public function offsetUnset($offset) { unset($this->_contacts[$offset]); } public function offsetExists($offset) { return isset($this->_contacts[$offset]); } public function sort($attribute = 'name') { $sortFct = 'sortBy' . ucfirst(strtolower($attribute)); if (!in_array($sortFct, get_class_methods('Contact'))) { throw new Exception('contact->sort(): Can\'t sort by ' . $attribute); } usort($this->contact, 'ContactList::' . $sortFct); } } public function Sort($property, $asc=true) { // this is where sorting logic takes place $_pd = $this->_contact->getProperty($property); if ($_pd == null) { user_error('Property '.$property.' does not exist in class '.$this->_contact->getName(), E_WARNING); return; } // set sortDescriptor ContactList::$sortProperty = $_pd; // and apply sorting usort($this->_array, array('ContactList', ($asc?'USortAsc':'USortDesc'))); } function getItems(){ return $this->_array; } class SortableItem extends ContactList { static public $sortProperty; static function USortAsc($a, $b) { /*@var $_pd ReflectionProperty*/ /* $_pd = self::$sortProperty; if ($_pd !== null) { if ($_pd->getValue($a) === $_pd->getValue($b)) return 0; else return (($_pd->getValue($a) < $_pd->getValue($b))?-1:1); } return 0; } static function USortDesc($a, $b) { return -(self::USortAsc($a,$b)); } } This approach keeps giving me PHP Warnings: usort() [function.usort]: of all kinds which I can provide later as needed to comment out those methods and definitions in order to test and fix some minor bugs of our program. **$billy parameters are already defined. $all -> addContact($billy); // --> ended up adding each contact manually above $all->Sort('name',true); $items = $all->getItems(); foreach($items as $contact) { echo $contact->__toString(); } $all->sort(); The reason for using usort is to re-arrange the order alphabetically by name but somehow is either stating that the function comparison needs to be an array or another errors which obviously I have seemed to pass. Any help would be greatly appreciated, thanks in advance.

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• Is it safe to assert a functions return type?

  - by wb

  This question is related to this question. I have several models stored in a collection. I loop through the collection and validate each field. Based on the input, a field can either be successful, have an error or a warning. Is it safe to unit test each decorator and assert that the type of object returned is what you would expect based on the given input? I could perhaps see this being an issue for a language with function return types since my validation function can return one of 3 types. This is the code I'm fiddling with: <!-- #include file = "../lib/Collection.asp" --> <style type="text/css"> td { padding: 4px; } td.error { background: #F00F00; } td.warning { background: #FC0; } </style> <% Class UserModel Private m_Name Private m_Age Private m_Height Public Property Let Name(value) m_Name = value End Property Public Property Get Name() Name = m_Name End Property Public Property Let Age(value) m_Age = value End Property Public Property Get Age() Age = m_Age End Property Public Property Let Height(value) m_Height = value End Property Public Property Get Height() Height = m_Height End Property End Class Class NameValidation Private m_Name Public Function Init(name) m_Name = name End Function Public Function Validate() Dim validationObject If Len(m_Name) < 5 Then Set validationObject = New ValidationError Else Set validationObject = New ValidationSuccess End If validationObject.CellValue = m_Name Set Validate = validationObject End Function End Class Class AgeValidation Private m_Age Public Function Init(age) m_Age = age End Function Public Function Validate() Dim validationObject If m_Age < 18 Then Set validationObject = New ValidationError ElseIf m_Age = 18 Then Set validationObject = New ValidationWarning Else Set validationObject = New ValidationSuccess End If validationObject.CellValue = m_Age Set Validate = validationObject End Function End Class Class HeightValidation Private m_Height Public Function Init(height) m_Height = height End Function Public Function Validate() Dim validationObject If m_Height > 400 Then Set validationObject = New ValidationError ElseIf m_Height = 324 Then Set validationObject = New ValidationWarning Else Set validationObject = New ValidationSuccess End If validationObject.CellValue = m_Height Set Validate = validationObject End Function End Class Class ValidationError Private m_CSSClass Private m_CellValue Public Property Get CSSClass() CSSClass = "error" End Property Public Property Let CellValue(value) m_CellValue = value End Property Public Property Get CellValue() CellValue = m_CellValue End Property End Class Class ValidationWarning Private m_CSSClass Private m_CellValue Public Property Get CSSClass() CSSClass = "warning" End Property Public Property Let CellValue(value) m_CellValue = value End Property Public Property Get CellValue() CellValue = m_CellValue End Property End Class Class ValidationSuccess Private m_CSSClass Private m_CellValue Public Property Get CSSClass() CSSClass = "" End Property Public Property Let CellValue(value) m_CellValue = value End Property Public Property Get CellValue() CellValue = m_CellValue End Property End Class Class ModelValidator Public Function ValidateModel(model) Dim modelValidation : Set modelValidation = New CollectionClass ' Validate name Dim name : Set name = New NameValidation name.Init model.Name modelValidation.Add name ' Validate age Dim age : Set age = New AgeValidation age.Init model.Age modelValidation.Add age ' Validate height Dim height : Set height = New HeightValidation height.Init model.Height modelValidation.Add height Dim validatedProperties : Set validatedProperties = New CollectionClass Dim modelVal For Each modelVal In modelValidation.Items() validatedProperties.Add modelVal.Validate() Next Set ValidateModel = validatedProperties End Function End Class Dim modelCollection : Set modelCollection = New CollectionClass Dim user1 : Set user1 = New UserModel user1.Name = "Mike" user1.Age = 12 user1.Height = 32 modelCollection.Add user1 Dim user2 : Set user2 = New UserModel user2.Name = "Phil" user2.Age = 18 user2.Height = 432 modelCollection.Add user2 Dim user3 : Set user3 = New UserModel user3.Name = "Michele" user3.Age = 32 user3.Height = 324 modelCollection.Add user3 ' Validate all models in the collection Dim modelValue Dim validatedModels : Set validatedModels = New CollectionClass For Each modelValue In modelCollection.Items() Dim objModelValidator : Set objModelValidator = New ModelValidator validatedModels.Add objModelValidator.ValidateModel(modelValue) Next %> <table> <tr> <td>Name</td> <td>Age</td> <td>Height</td> </tr> <% Dim r, c For Each r In validatedModels.Items() %><tr><% For Each c In r.Items() %><td class="<%= c.CSSClass %>"><%= c.CellValue %></td><% Next %></tr><% Next %> </table> Thank you.

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• EF Code First to SQL Azure

  - by Predrag Pejic

  I am using EF Code First to create a database on local .\SQLEXPRESS. Among others. I have these 2 classes: public class Shop { public int ShopID { get; set; } [Required(AllowEmptyStrings = false, ErrorMessage = "You must enter a name!")] [MaxLength(25, ErrorMessage = "Name must be 25 characters or less")] public string Name { get; set; } [Required(AllowEmptyStrings = false, ErrorMessage = "You must enter an address!")] [MaxLength(30, ErrorMessage = "Address must be 30 characters or less")] public string Address { get; set; } [Required(AllowEmptyStrings = false, ErrorMessage = "You must enter a valid city name!")] [MaxLength(30, ErrorMessage = "City name must be 30 characters or less")] public string City { get; set; } [Required(AllowEmptyStrings = false, ErrorMessage = "You must enter a phone number!")] [MaxLength(14, ErrorMessage = "Phone number must be 14 characters or less")] public string Phone { get; set; } [MaxLength(100, ErrorMessage = "Description must be 50 characters or less")] public string Description { get; set; } [Required(AllowEmptyStrings = false, ErrorMessage = "You must enter a WorkTime!")] public DateTime WorkTimeBegin { get; set; } [Required(AllowEmptyStrings = false, ErrorMessage = "You must enter a WorkTime!")] public DateTime WorkTimeEnd { get; set; } public DateTime? SaturdayWorkTimeBegin { get; set; } public DateTime? SaturdayWorkTimeEnd { get; set; } public DateTime? SundayWorkTimeBegin { get; set; } public DateTime? SundayWorkTimeEnd { get; set; } public int ShoppingPlaceID { get; set; } public virtual ShoppingPlace ShoppingPlace { get; set; } public virtual ICollection<Category> Categories { get; set; } } public class ShoppingPlace { [Key] public int ShopingplaceID { get; set; } [Required(AllowEmptyStrings = false, ErrorMessage = "You must enter a name!")] [MaxLength(25, ErrorMessage = "Name must be 25 characters or less")] public string Name { get; set; } [Required(AllowEmptyStrings = false, ErrorMessage = "You must enter an address!")] [MaxLength(50, ErrorMessage = "Address must be 50 characters or less")] public string Address { get; set; } [Required(AllowEmptyStrings = false, ErrorMessage = "You must enter a city name!")] [MaxLength(30, ErrorMessage = "City must be 30 characters or less")] public string City { get; set; } [Required(AllowEmptyStrings = false, ErrorMessage = "You must enter a valid phone number!")] [MaxLength(14, ErrorMessage = "Phone number must be 14 characters or less")] public string Phone { get; set; } public int ShoppingCenterID { get; set; } public virtual ShoppingCenter ShoppingCenter { get; set; } public virtual ICollection<Shop> Shops { get; set; } } and a method in DbContext: modelBuilder.Entity<Item>() .HasRequired(p => p.Category) .WithMany(a => a.Items) .HasForeignKey(a => a.CategoryID) .WillCascadeOnDelete(false); modelBuilder.Entity<Category>() .HasRequired(a => a.Shop) .WithMany(a => a.Categories) .HasForeignKey(a => a.ShopID) .WillCascadeOnDelete(false); modelBuilder.Entity<Shop>() .HasOptional(a => a.ShoppingPlace) .WithMany(a => a.Shops) .HasForeignKey(a => a.ShoppingPlaceID) .WillCascadeOnDelete(false); modelBuilder.Entity<ShoppingPlace>() .HasOptional(a => a.ShoppingCenter) .WithMany(a => a.ShoppingPlaces) .HasForeignKey(a => a.ShoppingCenterID) .WillCascadeOnDelete(false); Why I can't create Shop without creating and populating ShopingPlace. How to achieve that? EDIT: Tried with: modelBuilder.Entity<Shop>() .HasOptional(a => a.ShoppingPlace) .WithOptionalPrincipal(); modelBuilder.Entity<ShoppingPlace>() .HasOptional(a => a.ShoppingCenter) .WithOptionalPrincipal(); and it passed, but what is the difference? And why in SQL Server i am allowed to see ShoppingPlaceID and ShoppingPlace_ShopingPlaceID when in the case of Item and Category i see only one?

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• Unity – Part 5: Injecting Values

  - by Ricardo Peres

  Introduction This is the fifth post on Unity. You can find the introductory post here, the second post, on dependency injection here, a third one on Aspect Oriented Programming (AOP) here and the latest so far, on writing custom extensions, here. This time we will talk about injecting simple values. An Inversion of Control (IoC) / Dependency Injector (DI) container like Unity can be used for things other than injecting complex class dependencies. It can also be used for setting property values or method/constructor parameters whenever a class is built. The main difference is that these values do not have a lifetime manager associated with them and do not come from the regular IoC registration store. Unlike, for instance, MEF, Unity won’t let you register as a dependency a string or an integer, so you have to take a different approach, which I will describe in this post. Scenario Let’s imagine we have a base interface that describes a logger – the same as in previous examples: 1: public interface ILogger 2: { 3: void Log(String message); 4: } And a concrete implementation that writes to a file: 1: public class FileLogger : ILogger 2: { 3: public String Filename 4: { 5: get; 6: set; 7: } 8:  9: #region ILogger Members 10:  11: public void Log(String message) 12: { 13: using (Stream file = File.OpenWrite(this.Filename)) 14: { 15: Byte[] data = Encoding.Default.GetBytes(message); 16: 17: file.Write(data, 0, data.Length); 18: } 19: } 20:  21: #endregion 22: } And let’s say we want the Filename property to come from the application settings (appSettings) section on the Web/App.config file. As usual with Unity, there is an extensibility point that allows us to automatically do this, both with code configuration or statically on the configuration file. Extending Injection We start by implementing a class that will retrieve a value from the appSettings by inheriting from ValueElement: 1: sealed class AppSettingsParameterValueElement : ValueElement, IDependencyResolverPolicy 2: { 3: #region Private methods 4: private Object CreateInstance(Type parameterType) 5: { 6: Object configurationValue = ConfigurationManager.AppSettings[this.AppSettingsKey]; 7:  8: if (parameterType != typeof(String)) 9: { 10: TypeConverter typeConverter = this.GetTypeConverter(parameterType); 11:  12: configurationValue = typeConverter.ConvertFromInvariantString(configurationValue as String); 13: } 14:  15: return (configurationValue); 16: } 17: #endregion 18:  19: #region Private methods 20: private TypeConverter GetTypeConverter(Type parameterType) 21: { 22: if (String.IsNullOrEmpty(this.TypeConverterTypeName) == false) 23: { 24: return (Activator.CreateInstance(TypeResolver.ResolveType(this.TypeConverterTypeName)) as TypeConverter); 25: } 26: else 27: { 28: return (TypeDescriptor.GetConverter(parameterType)); 29: } 30: } 31: #endregion 32:  33: #region Public override methods 34: public override InjectionParameterValue GetInjectionParameterValue(IUnityContainer container, Type parameterType) 35: { 36: Object value = this.CreateInstance(parameterType); 37: return (new InjectionParameter(parameterType, value)); 38: } 39: #endregion 40:  41: #region IDependencyResolverPolicy Members 42:  43: public Object Resolve(IBuilderContext context) 44: { 45: Type parameterType = null; 46:  47: if (context.CurrentOperation is ResolvingPropertyValueOperation) 48: { 49: ResolvingPropertyValueOperation op = (context.CurrentOperation as ResolvingPropertyValueOperation); 50: PropertyInfo prop = op.TypeBeingConstructed.GetProperty(op.PropertyName); 51: parameterType = prop.PropertyType; 52: } 53: else if (context.CurrentOperation is ConstructorArgumentResolveOperation) 54: { 55: ConstructorArgumentResolveOperation op = (context.CurrentOperation as ConstructorArgumentResolveOperation); 56: String args = op.ConstructorSignature.Split('(')[1].Split(')')[0]; 57: Type[] types = args.Split(',').Select(a => Type.GetType(a.Split(' ')[0])).ToArray(); 58: ConstructorInfo ctor = op.TypeBeingConstructed.GetConstructor(types); 59: parameterType = ctor.GetParameters().Where(p => p.Name == op.ParameterName).Single().ParameterType; 60: } 61: else if (context.CurrentOperation is MethodArgumentResolveOperation) 62: { 63: MethodArgumentResolveOperation op = (context.CurrentOperation as MethodArgumentResolveOperation); 64: String methodName = op.MethodSignature.Split('(')[0].Split(' ')[1]; 65: String args = op.MethodSignature.Split('(')[1].Split(')')[0]; 66: Type[] types = args.Split(',').Select(a => Type.GetType(a.Split(' ')[0])).ToArray(); 67: MethodInfo method = op.TypeBeingConstructed.GetMethod(methodName, types); 68: parameterType = method.GetParameters().Where(p => p.Name == op.ParameterName).Single().ParameterType; 69: } 70:  71: return (this.CreateInstance(parameterType)); 72: } 73:  74: #endregion 75:  76: #region Public properties 77: [ConfigurationProperty("appSettingsKey", IsRequired = true)] 78: public String AppSettingsKey 79: { 80: get 81: { 82: return ((String)base["appSettingsKey"]); 83: } 84:  85: set 86: { 87: base["appSettingsKey"] = value; 88: } 89: } 90: #endregion 91: } As you can see from the implementation of the IDependencyResolverPolicy.Resolve method, this will work in three different scenarios: When it is applied to a property; When it is applied to a constructor parameter; When it is applied to an initialization method. The implementation will even try to convert the value to its declared destination, for example, if the destination property is an Int32, it will try to convert the appSettings stored string to an Int32. Injection By Configuration If we want to configure injection by configuration, we need to implement a custom section extension by inheriting from SectionExtension, and registering our custom element with the name “appSettings”: 1: sealed class AppSettingsParameterInjectionElementExtension : SectionExtension 2: { 3: public override void AddExtensions(SectionExtensionContext context) 4: { 5: context.AddElement<AppSettingsParameterValueElement>("appSettings"); 6: } 7: } And on the configuration file, for setting a property, we use it like this: 1: <appSettings> 2: <add key="LoggerFilename" value="Log.txt"/> 3: </appSettings> 4: <unity xmlns="http://schemas.microsoft.com/practices/2010/unity"> 5: <container> 6: <register type="MyNamespace.ILogger, MyAssembly" mapTo="MyNamespace.ConsoleLogger, MyAssembly"/> 7: <register type="MyNamespace.ILogger, MyAssembly" mapTo="MyNamespace.FileLogger, MyAssembly" name="File"> 8: <lifetime type="singleton"/> 9: <property name="Filename"> 10: <appSettings appSettingsKey="LoggerFilename"/> 11: </property> 12: </register> 13: </container> 14: </unity> If we would like to inject the value as a constructor parameter, it would be instead: 1: <unity xmlns="http://schemas.microsoft.com/practices/2010/unity"> 2: <sectionExtension type="MyNamespace.AppSettingsParameterInjectionElementExtension, MyAssembly" /> 3: <container> 4: <register type="MyNamespace.ILogger, MyAssembly" mapTo="MyNamespace.ConsoleLogger, MyAssembly"/> 5: <register type="MyNamespace.ILogger, MyAssembly" mapTo="MyNamespace.FileLogger, MyAssembly" name="File"> 6: <lifetime type="singleton"/> 7: <constructor> 8: <param name="filename" type="System.String"> 9: <appSettings appSettingsKey="LoggerFilename"/> 10: </param> 11: </constructor> 12: </register> 13: </container> 14: </unity> Notice the appSettings section, where we add a LoggerFilename entry, which is the same as the one referred by our AppSettingsParameterInjectionElementExtension extension. For more advanced behavior, you can add a TypeConverterName attribute to the appSettings declaration, where you can pass an assembly qualified name of a class that inherits from TypeConverter. This class will be responsible for converting the appSettings value to a destination type. Injection By Attribute If we would like to use attributes instead, we need to create a custom attribute by inheriting from DependencyResolutionAttribute: 1: [Serializable] 2: [AttributeUsage(AttributeTargets.Parameter | AttributeTargets.Property, AllowMultiple = false, Inherited = true)] 3: public sealed class AppSettingsDependencyResolutionAttribute : DependencyResolutionAttribute 4: { 5: public AppSettingsDependencyResolutionAttribute(String appSettingsKey) 6: { 7: this.AppSettingsKey = appSettingsKey; 8: } 9:  10: public String TypeConverterTypeName 11: { 12: get; 13: set; 14: } 15:  16: public String AppSettingsKey 17: { 18: get; 19: private set; 20: } 21:  22: public override IDependencyResolverPolicy CreateResolver(Type typeToResolve) 23: { 24: return (new AppSettingsParameterValueElement() { AppSettingsKey = this.AppSettingsKey, TypeConverterTypeName = this.TypeConverterTypeName }); 25: } 26: } As for file configuration, there is a mandatory property for setting the appSettings key and an optional TypeConverterName  for setting the name of a TypeConverter. Both the custom attribute and the custom section return an instance of the injector AppSettingsParameterValueElement that we implemented in the first place. Now, the attribute needs to be placed before the injected class’ Filename property: 1: public class FileLogger : ILogger 2: { 3: [AppSettingsDependencyResolution("LoggerFilename")] 4: public String Filename 5: { 6: get; 7: set; 8: } 9:  10: #region ILogger Members 11:  12: public void Log(String message) 13: { 14: using (Stream file = File.OpenWrite(this.Filename)) 15: { 16: Byte[] data = Encoding.Default.GetBytes(message); 17: 18: file.Write(data, 0, data.Length); 19: } 20: } 21:  22: #endregion 23: } Or, if we wanted to use constructor injection: 1: public class FileLogger : ILogger 2: { 3: public String Filename 4: { 5: get; 6: set; 7: } 8:  9: public FileLogger([AppSettingsDependencyResolution("LoggerFilename")] String filename) 10: { 11: this.Filename = filename; 12: } 13:  14: #region ILogger Members 15:  16: public void Log(String message) 17: { 18: using (Stream file = File.OpenWrite(this.Filename)) 19: { 20: Byte[] data = Encoding.Default.GetBytes(message); 21: 22: file.Write(data, 0, data.Length); 23: } 24: } 25:  26: #endregion 27: } Usage Just do: 1: ILogger logger = ServiceLocator.Current.GetInstance<ILogger>("File"); And off you go! A simple way do avoid hardcoded values in component registrations. Of course, this same concept can be applied to registry keys, environment values, XML attributes, etc, etc, just change the implementation of the AppSettingsParameterValueElement class. Next stop: custom lifetime managers.

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• LazyInitializationException when adding to a list that is held within a entity class using hibernate

  - by molleman

  Right so i am working with hibernate gilead and gwt to persist my data on users and files of a website. my users have a list of file locations. i am using annotations to map my classes to the database. i am getting a org.hibernate.LazyInitializationException when i try to add file locations to the list that is held in the user class. this is a method below that is overridden from a external file upload servlet class that i am using. when the file uploads it calls this method. the user1 is loaded from the database elsewhere. the exception occurs at user1.getFileLocations().add(fileLocation); . i dont understand it really at all.! any help would be great. the stack trace of the error is below public String executeAction(HttpServletRequest request, List<FileItem> sessionFiles) throws UploadActionException { for (FileItem item : sessionFiles) { if (false == item.isFormField()) { try { YFUser user1 = (YFUser)getSession().getAttribute(SESSION_USER); // This is the location where a file will be stored String fileLocationString = "/Users/Stefano/Desktop/UploadedFiles/" + user1.getUsername(); File fl = new File(fileLocationString); fl.mkdir(); // so here i will create the a file container for my uploaded file File file = File.createTempFile("upload-", ".bin",fl); // this is where the file is written to disk item.write(file); // the FileLocation object is then created FileLocation fileLocation = new FileLocation(); fileLocation.setLocation(fileLocationString); //test System.out.println("file path = "+file.getPath()); user1.getFileLocations().add(fileLocation); //the line above is where the exception occurs } catch (Exception e) { throw new UploadActionException(e.getMessage()); } } removeSessionFileItems(request); } return null; } //This is the class file for a Your Files User @Entity @Table(name = "yf_user_table") public class YFUser implements Serializable,ILightEntity { @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "user_id",nullable = false) private int userId; @Column(name = "username") private String username; @Column(name = "password") private String password; @Column(name = "email") private String email; @ManyToMany(cascade = CascadeType.ALL) @JoinTable(name = "USER_FILELOCATION", joinColumns = { @JoinColumn(name = "user_id") }, inverseJoinColumns = { @JoinColumn(name = "locationId") }) private List<FileLocation> fileLocations = new ArrayList<FileLocation>() ; public YFUser(){ } public int getUserId() { return userId; } private void setUserId(int userId) { this.userId = userId; } public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } public List<FileLocation> getFileLocations() { if(fileLocations ==null){ fileLocations = new ArrayList<FileLocation>(); } return fileLocations; } public void setFileLocations(List<FileLocation> fileLocations) { this.fileLocations = fileLocations; } /* public void addFileLocation(FileLocation location){ fileLocations.add(location); }*/ @Override public void addProxyInformation(String property, Object proxyInfo) { // TODO Auto-generated method stub } @Override public String getDebugString() { // TODO Auto-generated method stub return null; } @Override public Object getProxyInformation(String property) { // TODO Auto-generated method stub return null; } @Override public boolean isInitialized(String property) { // TODO Auto-generated method stub return false; } @Override public void removeProxyInformation(String property) { // TODO Auto-generated method stub } @Override public void setInitialized(String property, boolean initialised) { // TODO Auto-generated method stub } @Override public Object getValue() { // TODO Auto-generated method stub return null; } } @Entity @Table(name = "fileLocationTable") public class FileLocation implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "locationId", updatable = false, nullable = false) private int ieId; @Column (name = "location") private String location; public FileLocation(){ } public int getIeId() { return ieId; } private void setIeId(int ieId) { this.ieId = ieId; } public String getLocation() { return location; } public void setLocation(String location) { this.location = location; } } Apr 2, 2010 11:33:12 PM org.hibernate.LazyInitializationException <init> SEVERE: failed to lazily initialize a collection of role: com.example.client.YFUser.fileLocations, no session or session was closed org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.example.client.YFUser.fileLocations, no session or session was closed at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:380) at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationExceptionIfNotConnected(AbstractPersistentCollection.java:372) at org.hibernate.collection.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:365) at org.hibernate.collection.AbstractPersistentCollection.write(AbstractPersistentCollection.java:205) at org.hibernate.collection.PersistentBag.add(PersistentBag.java:297) at com.example.server.TestServiceImpl.saveFileLocation(TestServiceImpl.java:132) 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 net.sf.gilead.gwt.PersistentRemoteService.processCall(PersistentRemoteService.java:174) at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:224) at com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost(AbstractRemoteServiceServlet.java:62) at javax.servlet.http.HttpServlet.service(HttpServlet.java:713) at javax.servlet.http.HttpServlet.service(HttpServlet.java:806) at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:487) at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:362) at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216) at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181) at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:729) at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:405) at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152) at org.mortbay.jetty.handler.RequestLogHandler.handle(RequestLogHandler.java:49) at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152) at org.mortbay.jetty.Server.handle(Server.java:324) at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:505) at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:843) at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:647) at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:211) at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:380) at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:396) at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:488) Apr 2, 2010 11:33:12 PM net.sf.gilead.core.PersistentBeanManager clonePojo INFO: Third party instance, not cloned : org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.example.client.YFUser.fileLocations, no session or session was closed

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• Overriding GetHashCode in a mutable struct - What NOT to do?

  - by Kyle Baran

  I am using the XNA Framework to make a learning project. It has a Point struct which exposes an X and Y value; for the purpose of optimization, it breaks the rules for proper struct design, since its a mutable struct. As Marc Gravell, John Skeet, and Eric Lippert point out in their respective posts about GetHashCode() (which Point overrides), this is a rather bad thing, since if an object's values change while its contained in a hashmap (ie, LINQ queries), it can become "lost". However, I am making my own Point3D struct, following the design of Point as a guideline. Thus, it too is a mutable struct which overrides GetHashCode(). The only difference is that mine exposes and int for X, Y, and Z values, but is fundamentally the same. The signatures are below: public struct Point3D : IEquatable<Point3D> { public int X; public int Y; public int Z; public static bool operator !=(Point3D a, Point3D b) { } public static bool operator ==(Point3D a, Point3D b) { } public Point3D Zero { get; } public override int GetHashCode() { } public override bool Equals(object obj) { } public bool Equals(Point3D other) { } public override string ToString() { } } I have tried to break my struct in the way they describe, namely by storing it in a List<Point3D>, as well as changing the value via a method using ref, but I did not encounter they behavior they warn about (maybe a pointer might allow me to break it?). Am I being too cautious in my approach, or should I be okay to use it as is?

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• Is the IP from the source or target in this System.Net.Sockets.SocketException?

  - by Jeremy Mullin

  I'm making an outbound connection using a DNS name to a server other than the localhost, and I get this exception: System.Net.WebException: Unable to connect to the remote server --- System.Net.Sockets.SocketException: No connection could be made because the target machine actively refused it 127.0.0.1:5555 The text implies that the TARGET machine refused the connection, but the IP address and port are from the localhost, which is kind of confusing. So is that IP address really the outgoing IP and port, even though the exception was caused by the target refusing the connection? Or is the exception from the local firewall blocking the outgoing connection?

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• Relationship between Repository and Unit of Work

  - by NullOrEmpty

  I am going to implement a repository, and I would like to use the UOW pattern since the consumer of the repository could do several operations, and I want to commit them at once. After read several articles about the matter, I still don't get how to relate this two elements, depending on the article it is being done in a way u other. Sometimes the UOW is something internal to the repository: public class Repository { UnitOfWork _uow; public Repository() { _uow = IoC.Get<UnitOfWork>(); } public void Save(Entity e) { _uow.Track(e); } public void SubmittChanges() { SaveInStorage(_uow.GetChanges()); } } And sometimes it is external: public class Repository { public void Save(Entity e, UnitOfWork uow) { uow.Track(e); } public void SubmittChanges(UnitOfWork uow) { SaveInStorage(uow.GetChanges()); } } Other times, is the UOW whom references the Repository public class UnitOfWork { Repository _repository; public UnitOfWork(Repository repository) { _repository = repository; } public void Save(Entity e) { this.Track(e); } public void SubmittChanges() { _repository.Save(this.GetChanges()); } } How are these two elements related? UOW tracks the elements that needs be changed, and repository contains the logic to persist those changes, but... who call who? Does the last make more sense? Also, who manages the connection? If several operations have to be done in the repository, I think using the same connection and even transaction is more sound, so maybe put the connection object inside the UOW and this one inside the repository makes sense as well. Cheers

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• Which database engines support IP addresses as a native type?

  - by Matt McClellan

  I'm trying to find databases with support for IP addresses as a native type (as opposed to storing as a string, or an unsigned integer, which at least one commenter has already pointed out won't work for IPv6). The primary reason I'm looking for this is ease of development. For example, sorting on a "native" IP address column would be correct (as opposed to when it's stored as a string). I would assume support for such a type would also include useful operations such as determining if an IP address is inside a specified network for use in WHERE clauses. The only one I'm aware of so far is PostgreSQL with its inet class. Does anyone have any others?

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• Interview Questions that can be asked on TCP/IP, UDP, Socket Programming ?

  - by Shantanu Gupta

  I am going for an interview day after tomorrow where i will be asked vaious questions related to TCP/IP and UDP. As of now i have prepared theoritical knowledge about it. But now I am looking up for gaining some practicle knowledge related to how it works in a network. What all is going in vaious .NET classes. I want to create a very small application like a chat or something that can make me all these concepts very much clear. Could you please suggest some questions related to TCP/IP that you generally ask or that you might have faced. How communication is going from server to client. Right now I am studying TcpClient, TcpListener and UdpClient Class but I want to implement all of them so as to get aware about its working. Is Chat application a Tcp/IP application ? I would appreciate your help.

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• How to print PCL Directly to the printer? Vb.net VS 2010

  - by Justin

  Good day, I've been trying to upgrade an old Print Program that prints raw pcl directly to the printer. The print program takes a PCL Mask and a PCL Batch Spool File (just pcl with page turn commands, I think) merges them and sends them off to the printer. I'm able to send to the Printer a file stream of PCL but I get mixed results and i do not understand why printing is so difficult under .net. I mean yes there is the PrintDocument class, but to print PCL... Let's just say I'm ready to detach my printer from the network and burn it a live. Here is my class PrintDirect (rather a hybrid class) Imports System Imports System.Text Imports System.Runtime.InteropServices <StructLayout(LayoutKind.Sequential)> _ Public Structure DOCINFO <MarshalAs(UnmanagedType.LPWStr)> _ Public pDocName As String <MarshalAs(UnmanagedType.LPWStr)> _ Public pOutputFile As String <MarshalAs(UnmanagedType.LPWStr)> _ Public pDataType As String End Structure 'DOCINFO Public Class PrintDirect <DllImport("winspool.drv", CharSet:=CharSet.Unicode, ExactSpelling:=False, CallingConvention:=CallingConvention.StdCall)> _ Public Shared Function OpenPrinter(ByVal pPrinterName As String, ByRef phPrinter As IntPtr, ByVal pDefault As Integer) As Long End Function <DllImport("winspool.drv", CharSet:=CharSet.Unicode, ExactSpelling:=False, CallingConvention:=CallingConvention.StdCall)> _ Public Shared Function StartDocPrinter(ByVal hPrinter As IntPtr, ByVal Level As Integer, ByRef pDocInfo As DOCINFO) As Long End Function <DllImport("winspool.drv", CharSet:=CharSet.Unicode, ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _ Public Shared Function StartPagePrinter(ByVal hPrinter As IntPtr) As Long End Function <DllImport("winspool.drv", CharSet:=CharSet.Ansi, ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _ Public Shared Function WritePrinter(ByVal hPrinter As IntPtr, ByVal data As String, ByVal buf As Integer, ByRef pcWritten As Integer) As Long End Function <DllImport("winspool.drv", CharSet:=CharSet.Unicode, ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _ Public Shared Function EndPagePrinter(ByVal hPrinter As IntPtr) As Long End Function <DllImport("winspool.drv", CharSet:=CharSet.Unicode, ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _ Public Shared Function EndDocPrinter(ByVal hPrinter As IntPtr) As Long End Function <DllImport("winspool.drv", CharSet:=CharSet.Unicode, ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _ Public Shared Function ClosePrinter(ByVal hPrinter As IntPtr) As Long End Function 'Helps uses to work with the printer Public Class PrintJob ''' <summary> ''' The address of the printer to print to. ''' </summary> ''' <remarks></remarks> Public PrinterName As String = "" Dim lhPrinter As New System.IntPtr() ''' <summary> ''' The object deriving from the Win32 API, Winspool.drv. ''' Use this object to overide the settings defined in the PrintJob Class. ''' </summary> ''' <remarks>Only use this when absolutly nessacary.</remarks> Public OverideDocInfo As New DOCINFO() ''' <summary> ''' The PCL Control Character or the ascii escape character. \x1b ''' </summary> ''' <remarks>ChrW(27)</remarks> Public Const PCL_Control_Character As Char = ChrW(27) ''' <summary> ''' Opens a connection to a printer, if false the connection could not be established. ''' </summary> ''' <returns></returns> ''' <remarks></remarks> Public Function OpenPrint() As Boolean Dim rtn_val As Boolean = False PrintDirect.OpenPrinter(PrinterName, lhPrinter, 0) If Not lhPrinter = 0 Then rtn_val = True End If Return rtn_val End Function ''' <summary> ''' The name of the Print Document. ''' </summary> ''' <value></value> ''' <returns></returns> ''' <remarks></remarks> Public Property DocumentName As String Get Return OverideDocInfo.pDocName End Get Set(ByVal value As String) OverideDocInfo.pDocName = value End Set End Property ''' <summary> ''' The type of Data that will be sent to the printer. ''' </summary> ''' <value>Send the print data type, usually "RAW" or "LPR". To overide use the OverideDocInfo Object</value> ''' <returns>The DataType as it was provided, if it is not part of the enumeration it is set to "UNKNOWN".</returns> ''' <remarks></remarks> Public Property DocumentDataType As PrintDataType Get Select Case OverideDocInfo.pDataType.ToUpper Case "RAW" Return PrintDataType.RAW Case "LPR" Return PrintDataType.LPR Case Else Return PrintDataType.UNKOWN End Select End Get Set(ByVal value As PrintDataType) OverideDocInfo.pDataType = [Enum].GetName(GetType(PrintDataType), value) End Set End Property Public Property DocumentOutputFile As String Get Return OverideDocInfo.pOutputFile End Get Set(ByVal value As String) OverideDocInfo.pOutputFile = value End Set End Property Enum PrintDataType UNKOWN = 0 RAW = 1 LPR = 2 End Enum ''' <summary> ''' Initializes the printing matrix ''' </summary> ''' <param name="PrintLevel">I have no idea what the hack this is...</param> ''' <remarks></remarks> Public Sub OpenDocument(Optional ByVal PrintLevel As Integer = 1) PrintDirect.StartDocPrinter(lhPrinter, PrintLevel, OverideDocInfo) End Sub ''' <summary> ''' Starts the next page. ''' </summary> ''' <remarks></remarks> Public Sub StartPage() PrintDirect.StartPagePrinter(lhPrinter) End Sub ''' <summary> ''' Writes a string to the printer, can be used to write out a section of the document at a time. ''' </summary> ''' <param name="data">The String to Send out to the Printer.</param> ''' <returns>The pcWritten as an integer, 0 may mean the writter did not write out anything.</returns> ''' <remarks>Warning the buffer is automatically created by the lenegth of the string.</remarks> Public Function WriteToPrinter(ByVal data As String) As Integer Dim pcWritten As Integer = 0 PrintDirect.WritePrinter(lhPrinter, data, data.Length - 1, pcWritten) Return pcWritten End Function Public Sub EndPage() PrintDirect.EndPagePrinter(lhPrinter) End Sub Public Sub CloseDocument() PrintDirect.EndDocPrinter(lhPrinter) End Sub Public Sub ClosePrint() PrintDirect.ClosePrinter(lhPrinter) End Sub ''' <summary> ''' Opens a connection to a printer and starts a new document. ''' </summary> ''' <returns>If false the connection could not be established. </returns> ''' <remarks></remarks> Public Function Open() As Boolean Dim rtn_val As Boolean = False rtn_val = OpenPrint() If rtn_val Then OpenDocument() End If Return rtn_val End Function ''' <summary> ''' Closes the document and closes the connection to the printer. ''' </summary> ''' <remarks></remarks> Public Sub Close() CloseDocument() ClosePrint() End Sub End Class End Class 'PrintDirect Here is how I print my file. I'm simple printing the PCL Masks, to show proof of concept. But I can't even do that. I can effectively create PCL and send it the printer without reading the file and it works fine... Plus I get mixed results with different stream reader text encoding as well. Dim pJob As New PrintDirect.PrintJob pJob.DocumentName = " test doc" pJob.DocumentDataType = PrintDirect.PrintJob.PrintDataType.RAW pJob.PrinterName = sPrinter.GetDevicePath '//This is where you'd stick your device name, sPrinter stands for Selected Printer from a dropdown (combobox). 'pJob.DocumentOutputFile = "C:\temp\test-spool.txt" If Not pJob.OpenPrint() Then MsgBox("Unable to connect to " & pJob.PrinterName, MsgBoxStyle.OkOnly, "Print Error") Exit Sub End If pJob.OpenDocument() pJob.StartPage() Dim sr As New IO.StreamReader(Me.txtFile.Text, Text.Encoding.ASCII) '//I've got best results with ASCII before, but only mized. Dim line As String = sr.ReadLine 'Fix for fly code on first run 'If line = 27 Then line = PrintDirect.PrintJob.PCL_Control_Character Do While (Not line Is Nothing) pJob.WriteToPrinter(line) line = sr.ReadLine Loop 'pJob.WriteToPrinter(ControlChars.FormFeed) pJob.EndPage() pJob.CloseDocument() sr.Close() sr.Dispose() sr = Nothing pJob.Close() I was able to get to print the mask, in the morning... now I'm getting strange printer characters scattered through 5 pages... I'm totally clueless. I must have changed something or the printer is at fault. You can access my test Check Mask, here http://kscserver.com/so/chk_mask.zip .

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• .LazyInitializationException when adding to a list that is held within a entity class using hibernat

  - by molleman

  Right so i am working with hibernate gilead and gwt to persist my data on users and files of a website. my users have a list of file locations. i am using annotations to map my classes to the database. i am getting a org.hibernate.LazyInitializationException when i try to add file locations to the list that is held in the user class. this is a method below that is overridden from a external file upload servlet class that i am using. when the file uploads it calls this method. the user1 is loaded from the database elsewhere. the exception occurs at user1.getFileLocations().add(fileLocation); . i dont understand it really at all.! any help would be great. the stack trace of the error is below public String executeAction(HttpServletRequest request, List<FileItem> sessionFiles) throws UploadActionException { for (FileItem item : sessionFiles) { if (false == item.isFormField()) { try { YFUser user1 = (YFUser)getSession().getAttribute(SESSION_USER); // This is the location where a file will be stored String fileLocationString = "/Users/Stefano/Desktop/UploadedFiles/" + user1.getUsername(); File fl = new File(fileLocationString); fl.mkdir(); // so here i will create the a file container for my uploaded file File file = File.createTempFile("upload-", ".bin",fl); // this is where the file is written to disk item.write(file); // the FileLocation object is then created FileLocation fileLocation = new FileLocation(); fileLocation.setLocation(fileLocationString); //test System.out.println("file path = "+file.getPath()); user1.getFileLocations().add(fileLocation); //the line above is where the exception occurs } catch (Exception e) { throw new UploadActionException(e.getMessage()); } } removeSessionFileItems(request); } return null; } //This is the class file for a Your Files User @Entity @Table(name = "yf_user_table") public class YFUser implements Serializable,ILightEntity { @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "user_id",nullable = false) private int userId; @Column(name = "username") private String username; @Column(name = "password") private String password; @Column(name = "email") private String email; @ManyToMany(cascade = CascadeType.ALL) @JoinTable(name = "USER_FILELOCATION", joinColumns = { @JoinColumn(name = "user_id") }, inverseJoinColumns = { @JoinColumn(name = "locationId") }) private List<FileLocation> fileLocations = new ArrayList<FileLocation>() ; public YFUser(){ } public int getUserId() { return userId; } private void setUserId(int userId) { this.userId = userId; } public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } public List<FileLocation> getFileLocations() { if(fileLocations ==null){ fileLocations = new ArrayList<FileLocation>(); } return fileLocations; } public void setFileLocations(List<FileLocation> fileLocations) { this.fileLocations = fileLocations; } /* public void addFileLocation(FileLocation location){ fileLocations.add(location); }*/ @Override public void addProxyInformation(String property, Object proxyInfo) { // TODO Auto-generated method stub } @Override public String getDebugString() { // TODO Auto-generated method stub return null; } @Override public Object getProxyInformation(String property) { // TODO Auto-generated method stub return null; } @Override public boolean isInitialized(String property) { // TODO Auto-generated method stub return false; } @Override public void removeProxyInformation(String property) { // TODO Auto-generated method stub } @Override public void setInitialized(String property, boolean initialised) { // TODO Auto-generated method stub } @Override public Object getValue() { // TODO Auto-generated method stub return null; } } @Entity @Table(name = "fileLocationTable") public class FileLocation implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "locationId", updatable = false, nullable = false) private int ieId; @Column (name = "location") private String location; /* private List uploadedUsers = new ArrayList(); */ public FileLocation(){ } public int getIeId() { return ieId; } private void setIeId(int ieId) { this.ieId = ieId; } public String getLocation() { return location; } public void setLocation(String location) { this.location = location; } /* public List getUploadedUsers() { return uploadedUsers; } public void setUploadedUsers(List<YFUser> uploadedUsers) { this.uploadedUsers = uploadedUsers; } public void addUploadedUser(YFUser user){ uploadedUsers.add(user); } */ } Apr 2, 2010 11:33:12 PM org.hibernate.LazyInitializationException <init> SEVERE: failed to lazily initialize a collection of role: com.example.client.YFUser.fileLocations, no session or session was closed org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.example.client.YFUser.fileLocations, no session or session was closed at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:380) at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationExceptionIfNotConnected(AbstractPersistentCollection.java:372) at org.hibernate.collection.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:365) at org.hibernate.collection.AbstractPersistentCollection.write(AbstractPersistentCollection.java:205) at org.hibernate.collection.PersistentBag.add(PersistentBag.java:297) at com.example.server.TestServiceImpl.saveFileLocation(TestServiceImpl.java:132) 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 net.sf.gilead.gwt.PersistentRemoteService.processCall(PersistentRemoteService.java:174) at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:224) at com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost(AbstractRemoteServiceServlet.java:62) at javax.servlet.http.HttpServlet.service(HttpServlet.java:713) at javax.servlet.http.HttpServlet.service(HttpServlet.java:806) at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:487) at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:362) at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216) at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181) at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:729) at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:405) at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152) at org.mortbay.jetty.handler.RequestLogHandler.handle(RequestLogHandler.java:49) at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152) at org.mortbay.jetty.Server.handle(Server.java:324) at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:505) at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:843) at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:647) at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:211) at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:380) at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:396) at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:488) Apr 2, 2010 11:33:12 PM net.sf.gilead.core.PersistentBeanManager clonePojo INFO: Third party instance, not cloned : org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.example.client.YFUser.fileLocations, no session or session was closed

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• C# delegates problem

  - by Mick Taylor

  Hello I am getting the following error from my C# Windows Application: Error 1 No overload for 'CreateLabelInPanel' matches delegate 'WorksOrderStore.ProcessDbConnDetailsDelegate' H:\c\WorksOrderFactory\WorksOrderFactory\WorksOrderClient.cs 43 39 WorksOrderFactory I have 3 .cs files that essentially: Opens a windows Has an option for the users to connect to a db When that is selected, the system will go off and connect to the db, and load some data in (just test data for now) Then using a delegate, the system should do soemthing, which for testing will be to create a label. However I haven't coded this part yet. But I can't build until I get this error sorted. The 3 fiels are called: WorksOrderClient.cs (which is the MAIN) WorksOrderStore.cs LoginBox.cs Here's the code for each file: WorksOrderClient.cs using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using WorksOrderStore; namespace WorksOrderFactory { using WorksOrderStore; public partial class WorksOrderClient : Form { LoginBox lb = new LoginBox(); private static WorksOrderDB wodb = new WorksOrderDB(); private static int num_conns = 0; public WorksOrderClient() { InitializeComponent(); } private void connectToADBToolStripMenuItem_Click(object sender, EventArgs e) { lb.ShowDialog(); lb.Visible = true; } public static bool createDBConnDetObj(string username, string password, string database) { // increase the number of connections num_conns = num_conns + 1; // create the connection object wodb.AddDbConnDetails(username, password, database, num_conns); // create a new delegate object associated with the static // method WorksOrderClient.createLabelInPanel wodb.ProcessDbConnDetails(new ProcessDbConnDetailsDelegate(CreateLabelInPanel)); return true; } static void CreateLabelInPanel(DbConnDetails dbcd) { Console.Write("hellO"); string tmp = (string)dbcd.username; //Console.Write(tmp); } private void WorksOrderClient_Load(object sender, EventArgs e) { } } } WorksOrderStore.cs using System; using System.Collections.Generic; using System.Linq; using System.Text; using WorksOrderFactory; namespace WorksOrderStore { using System.Collections; // Describes a book in the book list: public struct WorksOrder { public string contractor_code { get; set; } // contractor ID public string email_address { get; set; } // contractors email address public string date_issued { get; set; } // date the works order was issued public string wo_ref { get; set; } // works order ref public string status { get; set; } // status ... not used public job_status js { get; set; } // status of this worksorder within this system public WorksOrder(string contractor_code, string email_address, string date_issued, string wo_ref) : this() { this.contractor_code = contractor_code; this.email_address = email_address; this.date_issued = date_issued; this.wo_ref = wo_ref; this.js = job_status.Pending; } } // Declare a delegate type for processing a WorksOrder: //public delegate void ProcessWorksOrderDelegate(WorksOrder worksorder); // Maintains a worksorder database. public class WorksOrderDB { // List of all worksorders in the database: ArrayList list = new ArrayList(); // Add a worksorder to the database: public void AddWorksOrder(string contractor_code, string email_address, string date_issued, string wo_ref) { list.Add(new WorksOrder(contractor_code, email_address, date_issued, wo_ref)); } // Call a passed-in delegate on each pending works order to process it: /*public void ProcessPendingWorksOrders(ProcessWorksOrderDelegate processWorksOrder) { foreach (WorksOrder wo in list) { if (wo.js.Equals(job_status.Pending)) // Calling the delegate: processWorksOrder(wo); } }*/ // Add a DbConnDetails to the database: public void AddDbConnDetails(string username, string password, string database, int conn_num) { list.Add(new DbConnDetails(username, password, database, conn_num)); } // Call a passed-in delegate on each dbconndet to process it: public void ProcessDbConnDetails(ProcessDbConnDetailsDelegate processDBConnDetails) { foreach (DbConnDetails wo in list) { processDBConnDetails(wo); } } } // statuses for worksorders in this system public enum job_status { Pending, InProgress, Completed } public struct DbConnDetails { public string username { get; set; } // username public string password { get; set; } // password public string database { get; set; } // database public int conn_num { get; set; } // this objects connection number. public ArrayList woList { get; set; } // list of works orders for this connection // this constructor just sets the db connection details // the woList array will get created later .. not a lot later but a bit. public DbConnDetails(string username, string password, string database, int conn_num) : this() { this.username = username; this.password = password; this.database = database; this.conn_num = conn_num; woList = new ArrayList(); } } // Declare a delegate type for processing a DbConnDetails: public delegate void ProcessDbConnDetailsDelegate(DbConnDetails dbConnDetails); } and LoginBox.cs using System; using System.Collections.Generic; using System.ComponentModel; using System.Drawing; using System.Data; using System.Linq; using System.Text; using System.Windows.Forms; namespace WorksOrderFactory { public partial class LoginBox : Form { public LoginBox() { InitializeComponent(); } private void LoginBox_Load(object sender, EventArgs e) { this.Visible = true; this.Show(); //usernameText.Text = "Username"; //new Font(usernameText.Font, FontStyle.Italic); } private void cancelBtn_Click(object sender, EventArgs e) { this.Close(); } private void loginBtn_Click(object sender, EventArgs e) { // set up a connection details object. bool success = WorksOrderClient.createDBConnDetObj(usernameText.Text, passwordText.Text, databaseText.Text); } private void LoginBox_Load_1(object sender, EventArgs e) { } } } Any ideas?? Cheers, m

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• Understanding C# async / await (1) Compilation

  - by Dixin

  Now the async / await keywords are in C#. Just like the async and ! in F#, this new C# feature provides great convenience. There are many nice documents talking about how to use async / await in specific scenarios, like using async methods in ASP.NET 4.5 and in ASP.NET MVC 4, etc. In this article we will look at the real code working behind the syntax sugar. According to MSDN: The async modifier indicates that the method, lambda expression, or anonymous method that it modifies is asynchronous. Since lambda expression / anonymous method will be compiled to normal method, we will focus on normal async method. Preparation First of all, Some helper methods need to make up. internal class HelperMethods { internal static int Method(int arg0, int arg1) { // Do some IO. WebClient client = new WebClient(); Enumerable.Repeat("http://weblogs.asp.net/dixin", 10) .Select(client.DownloadString).ToArray(); int result = arg0 + arg1; return result; } internal static Task<int> MethodTask(int arg0, int arg1) { Task<int> task = new Task<int>(() => Method(arg0, arg1)); task.Start(); // Hot task (started task) should always be returned. return task; } internal static void Before() { } internal static void Continuation1(int arg) { } internal static void Continuation2(int arg) { } } Here Method() is a long running method doing some IO. Then MethodTask() wraps it into a Task and return that Task. Nothing special here. Await something in async method Since MethodTask() returns Task, let’s try to await it: internal class AsyncMethods { internal static async Task<int> MethodAsync(int arg0, int arg1) { int result = await HelperMethods.MethodTask(arg0, arg1); return result; } } Because we used await in the method, async must be put on the method. Now we get the first async method. According to the naming convenience, it is named MethodAsync. Of course a async method can be awaited. So we have a CallMethodAsync() to call MethodAsync(): internal class AsyncMethods { internal static async Task<int> CallMethodAsync(int arg0, int arg1) { int result = await MethodAsync(arg0, arg1); return result; } } After compilation, MethodAsync() and CallMethodAsync() becomes the same logic. This is the code of MethodAsyc(): internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MethodAsync(int arg0, int arg1) { MethodAsyncStateMachine methodAsyncStateMachine = new MethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; methodAsyncStateMachine.Builder.Start(ref methodAsyncStateMachine); return methodAsyncStateMachine.Builder.Task; } } It just creates and starts a state machine, MethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Result; private TaskAwaiter<int> awaitor; void IAsyncStateMachine.MoveNext() { try { if (this.State != 0) { this.awaitor = HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaitor.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaitor, ref this); return; } } else { this.State = -1; } this.Result = this.awaitor.GetResult(); } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); return; } this.State = -2; this.Builder.SetResult(this.Result); } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine param0) { this.Builder.SetStateMachine(param0); } } The generated code has been refactored, so it is readable and can be compiled. Several things can be observed here: The async modifier is gone, which shows, unlike other modifiers (e.g. static), there is no such IL/CLR level “async” stuff. It becomes a AsyncStateMachineAttribute. This is similar to the compilation of extension method. The generated state machine is very similar to the state machine of C# yield syntax sugar. The local variables (arg0, arg1, result) are compiled to fields of the state machine. The real code (await HelperMethods.MethodTask(arg0, arg1)) is compiled into MoveNext(): HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(). CallMethodAsync() will create and start its own state machine CallMethodAsyncStateMachine: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(CallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> CallMethodAsync(int arg0, int arg1) { CallMethodAsyncStateMachine callMethodAsyncStateMachine = new CallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; callMethodAsyncStateMachine.Builder.Start(ref callMethodAsyncStateMachine); return callMethodAsyncStateMachine.Builder.Task; } } CallMethodAsyncStateMachine has the same logic as MethodAsyncStateMachine above. The detail of the state machine will be discussed soon. Now it is clear that: async /await is a C# language level syntax sugar. There is no difference to await a async method or a normal method. As long as a method returns Task, it is awaitable. State machine and continuation To demonstrate more details in the state machine, a more complex method is created: internal class AsyncMethods { internal static async Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; } } In this method: There are multiple awaits. There are code before the awaits, and continuation code after each await After compilation, this multi-await method becomes the same as above single-await methods: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; multiCallMethodAsyncStateMachine.Builder.Start(ref multiCallMethodAsyncStateMachine); return multiCallMethodAsyncStateMachine.Builder.Task; } } It creates and starts one single state machine, MultiCallMethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Arg2; public int Arg3; public int ResultOfAwait1; public int ResultOfAwait2; public int ResultToReturn; private TaskAwaiter<int> awaiter; void IAsyncStateMachine.MoveNext() { try { switch (this.State) { case -1: HelperMethods.Before(); this.awaiter = AsyncMethods.MethodAsync(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 0: this.ResultOfAwait1 = this.awaiter.GetResult(); HelperMethods.Continuation1(this.ResultOfAwait1); this.awaiter = AsyncMethods.MethodAsync(this.Arg2, this.Arg3).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 1; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 1: this.ResultOfAwait2 = this.awaiter.GetResult(); HelperMethods.Continuation2(this.ResultOfAwait2); this.ResultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; this.State = -2; this.Builder.SetResult(this.ResultToReturn); break; } } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); } } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine) { this.Builder.SetStateMachine(stateMachine); } } Once again, the above state machine code is already refactored, but it still has a lot of things. More clean up can be done if we only keep the core logic, and the state machine can become very simple: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { // State: // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End public int State; public TaskCompletionSource<int> ResultToReturn; // int resultToReturn ... public int Arg0; // int Arg0 public int Arg1; // int arg1 public int Arg2; // int arg2 public int Arg3; // int arg3 public int ResultOfAwait1; // int resultOfAwait1 ... public int ResultOfAwait2; // int resultOfAwait2 ... private Task<int> currentTaskToAwait; /// <summary> /// Moves the state machine to its next state. /// </summary> public void MoveNext() // IAsyncStateMachine member. { try { switch (this.State) { // Original code is split by "await"s into "case"s: // case -1: // HelperMethods.Before(); // MethodAsync(Arg0, arg1); // case 0: // int resultOfAwait1 = await ... // HelperMethods.Continuation1(resultOfAwait1); // MethodAsync(arg2, arg3); // case 1: // int resultOfAwait2 = await ... // HelperMethods.Continuation2(resultOfAwait2); // int resultToReturn = resultOfAwait1 + resultOfAwait2; // return resultToReturn; case -1: // -1 is begin. HelperMethods.Before(); // Code before 1st await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg0, this.Arg1); // 1st task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 0. this.State = 0; MultiCallMethodAsyncStateMachine that1 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => that1.MoveNext()); break; case 0: // Now 1st await is done. this.ResultOfAwait1 = this.currentTaskToAwait.Result; // Get 1st await's result. HelperMethods.Continuation1(this.ResultOfAwait1); // Code after 1st await and before 2nd await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg2, this.Arg3); // 2nd task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 1. this.State = 1; MultiCallMethodAsyncStateMachine that2 = this; this.currentTaskToAwait.ContinueWith(_ => that2.MoveNext()); break; case 1: // Now 2nd await is done. this.ResultOfAwait2 = this.currentTaskToAwait.Result; // Get 2nd await's result. HelperMethods.Continuation2(this.ResultOfAwait2); // Code after 2nd await. int resultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; // Code after 2nd await. // End with resultToReturn. this.State = -2; // -2 is end. this.ResultToReturn.SetResult(resultToReturn); break; } } catch (Exception exception) { // End with exception. this.State = -2; // -2 is end. this.ResultToReturn.SetException(exception); } } /// <summary> /// Configures the state machine with a heap-allocated replica. /// </summary> /// <param name="stateMachine">The heap-allocated replica.</param> [DebuggerHidden] public void SetStateMachine(IAsyncStateMachine stateMachine) // IAsyncStateMachine member. { // No core logic. } } Only Task and TaskCompletionSource are involved in this version. And MultiCallMethodAsync() can be simplified to: [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, ResultToReturn = new TaskCompletionSource<int>(), // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End State = -1 }; multiCallMethodAsyncStateMachine.MoveNext(); // Original code are moved into this method. return multiCallMethodAsyncStateMachine.ResultToReturn.Task; } Now the whole state machine becomes very clean - it is about callback: Original code are split into pieces by “await”s, and each piece is put into each “case” in the state machine. Here the 2 awaits split the code into 3 pieces, so there are 3 “case”s. The “piece”s are chained by callback, that is done by Builder.AwaitUnsafeOnCompleted(callback), or currentTaskToAwait.ContinueWith(callback) in the simplified code. A previous “piece” will end with a Task (which is to be awaited), when the task is done, it will callback the next “piece”. The state machine’s state works with the “case”s to ensure the code “piece”s executes one after another. Callback If we focus on the point of callback, the simplification  can go even further – the entire state machine can be completely purged, and we can just keep the code inside MoveNext(). Now MultiCallMethodAsync() becomes: internal static Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { TaskCompletionSource<int> taskCompletionSource = new TaskCompletionSource<int>(); try { // Oringinal code begins. HelperMethods.Before(); MethodAsync(arg0, arg1).ContinueWith(await1 => { int resultOfAwait1 = await1.Result; HelperMethods.Continuation1(resultOfAwait1); MethodAsync(arg2, arg3).ContinueWith(await2 => { int resultOfAwait2 = await2.Result; HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; // Oringinal code ends. taskCompletionSource.SetResult(resultToReturn); }); }); } catch (Exception exception) { taskCompletionSource.SetException(exception); } return taskCompletionSource.Task; } Please compare with the original async / await code: HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; Yeah that is the magic of C# async / await: Await is not to wait. In a await expression, a Task object will be return immediately so that execution is not blocked. The continuation code is compiled as that Task’s callback code. When that task is done, continuation code will execute. Please notice that many details inside the state machine are omitted for simplicity, like context caring, etc. If you want to have a detailed picture, please do check out the source code of AsyncTaskMethodBuilder and TaskAwaiter.

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• Replacing “if”s with your own number system

  - by Michael Williamson

  During our second code retreat at Red Gate, the restriction for one of the sessions was disallowing the use of if statements. That includes other constructs that have the same effect, such as switch statements or loops that will only be executed zero or one times. The idea is to encourage use of polymorphism instead, and see just how far it can be used to get rid of “if”s. The main place where people struggled to get rid of numbers from their implementation of Conway’s Game of Life was the piece of code that decides whether a cell is live or dead in the next generation. For instance, for a cell that’s currently live, the code might look something like this: if (numberOfNeighbours == 2 || numberOfNeighbours == 3) { return CellState.LIVE; } else { return CellState.DEAD; } The problem is that we need to change behaviour depending on the number of neighbours each cell has, but polymorphism only allows us to switch behaviour based on the type of a value. It follows that the solution is to make different numbers have different types: public interface IConwayNumber { IConwayNumber Increment(); CellState LiveCellNextGeneration(); } public class Zero : IConwayNumber { public IConwayNumber Increment() { return new One(); } public CellState LiveCellNextGeneration() { return CellState.DEAD; } } public class One : IConwayNumber { public IConwayNumber Increment() { return new Two(); } public CellState LiveCellNextGeneration() { return CellState.LIVE; } } public class Two : IConwayNumber { public IConwayNumber Increment() { return new ThreeOrMore(); } public CellState LiveCellNextGeneration() { return CellState.LIVE; } } public class ThreeOrMore : IConwayNumber { public IConwayNumber Increment() { return this; } public CellState LiveCellNextGeneration() { return CellState.DEAD; } } In the code that counts the number of neighbours, we use our new number system by starting with Zero and incrementing when we find a neighbour. To choose the next state of the cell, rather than inspecting the number of neighbours, we ask the number of neighbours for the next state directly: return numberOfNeighbours.LiveCellNextGeneration(); And now we have no “if”s! If C# had double-dispatch, or if we used the visitor pattern, we could move the logic for choosing the next cell out of the number classes, which might feel a bit more natural. I suspect that reimplementing the natural numbers is still going to feel about the same amount of crazy though.

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• How to handle "circular dependency" in dependency injection

  - by Roel

  The title says "Circular Dependency", but it is not the correct wording, because to me the design seems solid. However, consider the following scenario, where the blue parts are given from external partner, and orange is my own implementation. Also assume there is more then one ConcreteMain, but I want to use a specific one. (In reality, each class has some more dependencies, but I tried to simplify it here) I would like to instanciate all of this with Depency Injection (Unity), but I obviously get a StackOverflowException on the following code, because Runner tries to instantiate ConcreteMain, and ConcreteMain needs a Runner. IUnityContainer ioc = new UnityContainer(); ioc.RegisterType<IMain, ConcreteMain>() .RegisterType<IMainCallback, Runner>(); var runner = ioc.Resolve<Runner>(); How can I avouid this? Is there any way to structure this so that I can use it with DI? The scenario I'm doing now is setting everything up manually, but that puts a hard dependency on ConcreteMain in the class which instantiates it. This is what i'm trying to avoid (with Unity registrations in configuration). All source code below (very simplified example!); public class Program { public static void Main(string[] args) { IUnityContainer ioc = new UnityContainer(); ioc.RegisterType<IMain, ConcreteMain>() .RegisterType<IMainCallback, Runner>(); var runner = ioc.Resolve<Runner>(); Console.WriteLine("invoking runner..."); runner.DoSomethingAwesome(); Console.ReadLine(); } } public class Runner : IMainCallback { private readonly IMain mainServer; public Runner(IMain mainServer) { this.mainServer = mainServer; } public void DoSomethingAwesome() { Console.WriteLine("trying to do something awesome"); mainServer.DoSomething(); } public void SomethingIsDone(object something) { Console.WriteLine("hey look, something is finally done."); } } public interface IMain { void DoSomething(); } public interface IMainCallback { void SomethingIsDone(object something); } public abstract class AbstractMain : IMain { protected readonly IMainCallback callback; protected AbstractMain(IMainCallback callback) { this.callback = callback; } public abstract void DoSomething(); } public class ConcreteMain : AbstractMain { public ConcreteMain(IMainCallback callback) : base(callback){} public override void DoSomething() { Console.WriteLine("starting to do something..."); var task = Task.Factory.StartNew(() =>{ Thread.Sleep(5000);/*very long running task*/ }); task.ContinueWith(t => callback.SomethingIsDone(true)); } }

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• Loading class instance from XML with Texture2D

  - by Thegluestickman

  I'm having trouble with XML and XNA. I want to be able to load weapon settings through XML to make my weapons easier to make and to have less code in the actual project file. So I started out making a basic XML document, something to just assign variables with. But no matter what I changed it gave me a new error every time. The code below gives me a "XML element 'Tag' not found", I added and it started to say the variables weren't found. What I wanted to do in the XML file as well, was load a texture for the file too. So I created a static class to hold my texture values, then in the Texture tag of my XML document I would set it to that instance too. I think that's were the problems are occuring because that's where the "XML element 'Tag' not found" error is pointing me too. My XML document: <XnaContent> <Asset Type="ConversationEngine.Weapon"> <weaponStrength>0</weaponStrength> <damageModifiers>0</damageModifiers> <speed>0</speed> <magicDefense>0</magicDefense> <description>0</description> <identifier>0</identifier> <weaponTexture>LoadWeaponTextures.ironSword</weaponTexture> </Asset> </XnaContent> My Class to load the weapon XML: public class Weapon { public int weaponStrength; public int damageModifiers; public int speed; public int magicDefense; public string description; public string identifier; public Texture2D weaponTexture; } public static class LoadWeaponXML { static Weapon Weapons; public static Weapon WeaponLoad(ContentManager content, int id) { Weapons = content.Load<Weapon>(@"Weapons/" + id); return Weapons; } } public static class LoadWeaponTextures { public static Texture2D ironSword; public static void TextureLoad(ContentManager content) { ironSword = content.Load<Texture2D>("Sword"); } } I'm not entirely sure if you can load textures through XML, but any help would be greatly appreciated.

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• nginx problem accessing virtual hosts

  - by Sc0rian

  I am setting up nginx as a reverse proxy. The server runs on directadmin and lamp stack. I have nginx running on port 81. I can access all my sites (including virtual ips) on the port 81. However when I forward the traffic from port 80 to 81, the virtual ips have a message saying "Apache is running normally". Server IPs are fine, and I can still access virtual IP's on 81. [root@~]# netstat -an | grep LISTEN | egrep ":80|:81" tcp 0 0 <virtual ip>:81 0.0.0.0:* LISTEN tcp 0 0 <virtual ip>:81 0.0.0.0:* LISTEN tcp 0 0 <serverip>:81 0.0.0.0:* LISTEN tcp 0 0 :::80 :::* LISTEN apache 24090 0.6 1.3 29252 13612 ? S 18:34 0:00 /usr/sbin/httpd -k start -DSSL apache 24092 0.9 2.1 39584 22056 ? S 18:34 0:00 /usr/sbin/httpd -k start -DSSL apache 24096 0.2 1.9 35892 20256 ? S 18:34 0:00 /usr/sbin/httpd -k start -DSSL apache 24120 0.3 1.7 35752 17840 ? S 18:34 0:00 /usr/sbin/httpd -k start -DSSL apache 24495 0.0 1.4 30892 14756 ? S 18:35 0:00 /usr/sbin/httpd -k start -DSSL apache 24496 1.0 2.1 39892 22164 ? S 18:35 0:00 /usr/sbin/httpd -k start -DSSL apache 24516 1.5 3.6 55496 38040 ? S 18:35 0:00 /usr/sbin/httpd -k start -DSSL apache 24519 0.1 1.2 28996 13224 ? S 18:35 0:00 /usr/sbin/httpd -k start -DSSL apache 24521 2.7 4.0 58244 41984 ? S 18:35 0:00 /usr/sbin/httpd -k start -DSSL apache 24522 0.0 1.2 29124 12672 ? S 18:35 0:00 /usr/sbin/httpd -k start -DSSL apache 24524 0.0 1.1 28740 12364 ? S 18:35 0:00 /usr/sbin/httpd -k start -DSSL apache 24535 1.1 1.7 36008 17876 ? S 18:35 0:00 /usr/sbin/httpd -k start -DSSL apache 24536 0.0 1.1 28592 12084 ? S 18:35 0:00 /usr/sbin/httpd -k start -DSSL apache 24537 0.0 1.1 28592 12112 ? S 18:35 0:00 /usr/sbin/httpd -k start -DSSL apache 24539 0.0 0.0 0 0 ? Z 18:35 0:00 [httpd] <defunct> apache 24540 0.0 1.1 28592 11540 ? S 18:35 0:00 /usr/sbin/httpd -k start -DSSL apache 24541 0.0 1.1 28592 11548 ? S 18:35 0:00 /usr/sbin/httpd -k start -DSSL root 24548 0.0 0.0 4132 752 pts/0 R+ 18:35 0:00 egrep apache|nginx root 28238 0.0 0.0 19576 284 ? Ss May29 0:00 nginx: master process /usr/local/nginx/sbin/nginx -c /usr/local/nginx/conf/nginx.conf apache 28239 0.0 0.0 19888 804 ? S May29 0:00 nginx: worker process apache 28240 0.0 0.0 19888 548 ? S May29 0:00 nginx: worker process apache 28241 0.0 0.0 19736 484 ? S May29 0:00 nginx: cache manager process here is my nginx conf: cat /usr/local/nginx/conf/nginx.conf user apache apache; worker_processes 2; # Set it according to what your CPU have. 4 Cores = 4 worker_rlimit_nofile 8192; pid /var/run/nginx.pid; events { worker_connections 1024; } http { include mime.types; default_type application/octet-stream; log_format main '$remote_addr - $remote_user [$time_local] ' '"$request" $status $body_bytes_sent "$http_referer" ' '"$http_user_agent" "$http_x_forwarded_for"'; server_tokens off; access_log /var/log/nginx_access.log main; error_log /var/log/nginx_error.log debug; server_names_hash_bucket_size 64; sendfile on; tcp_nopush on; tcp_nodelay off; keepalive_timeout 30; gzip on; gzip_comp_level 9; gzip_proxied any; proxy_buffering on; proxy_cache_path /usr/local/nginx/proxy_temp levels=1:2 keys_zone=one:15m inactive=7d max_size=1000m; proxy_buffer_size 16k; proxy_buffers 100 8k; proxy_connect_timeout 60; proxy_send_timeout 60; proxy_read_timeout 60; server { listen <server ip>:81 default rcvbuf=8192 sndbuf=16384 backlog=32000; # Real IP here server_name <server host name> _; # "_" is for handle all hosts that are not described by server_name charset off; access_log /var/log/nginx_host_general.access.log main; location / { proxy_set_header Host $host; proxy_set_header X-Real-IP $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_pass http://<server ip>; # Real IP here client_max_body_size 16m; client_body_buffer_size 128k; proxy_buffering on; proxy_connect_timeout 90; proxy_send_timeout 90; proxy_read_timeout 120; proxy_buffer_size 16k; proxy_buffers 32 32k; proxy_busy_buffers_size 64k; proxy_temp_file_write_size 64k; } location /nginx_status { stub_status on; access_log off; allow 127.0.0.1; deny all; } } include /usr/local/nginx/vhosts/*.conf; } here is my vhost conf: # cat /usr/local/nginx/vhosts/1.conf server { listen <virt ip>:81 default rcvbuf=8192 sndbuf=16384 backlog=32000; # Real IP here server_name <virt domain name>.com ; # "_" is for handle all hosts that are not described by server_name charset off; access_log /var/log/nginx_host_general.access.log main; location / { proxy_set_header Host $host; proxy_set_header X-Real-IP $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_pass http://<virt ip>; # Real IP here client_max_body_size 16m; client_body_buffer_size 128k; proxy_buffering on; proxy_connect_timeout 90; proxy_send_timeout 90; proxy_read_timeout 120; proxy_buffer_size 16k; proxy_buffers 32 32k; proxy_busy_buffers_size 64k; proxy_temp_file_write_size 64k; } }

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• Only draw visible objects to the camera in 2D

  - by Deukalion

  I have Map, each map has an array of Ground, each Ground consists of an array of VertexPositionTexture and a texture name reference so it renders a texture at these points (as a shape through triangulation). Now when I render my map I only want to get a list of all objects that are visible in the camera. (So I won't loop through more than I have to) Structs: public struct Map { public Ground[] Ground { get; set; } } public struct Ground { public int[] Indexes { get; set; } public VertexPositionNormalTexture[] Points { get; set; } public Vector3 TopLeft { get; set; } public Vector3 TopRight { get; set; } public Vector3 BottomLeft { get; set; } public Vector3 BottomRight { get; set; } } public struct RenderBoundaries<T> { public BoundingBox Box; public T Items; } when I load a map: foreach (Ground ground in CurrentMap.Ground) { Boundaries.Add(new RenderBoundaries<Ground>() { Box = BoundingBox.CreateFromPoints(new Vector3[] { ground.TopLeft, ground.TopRight, ground.BottomLeft, ground.BottomRight }), Items = ground }); } TopLeft, TopRight, BottomLeft, BottomRight are simply the locations of each corner that the shape make. A rectangle. When I try to loop through only the objects that are visible I do this in my Draw method: public int Draw(GraphicsDevice device, ICamera camera) { BoundingFrustum frustum = new BoundingFrustum(camera.View * camera.Projection); // Visible count int count = 0; EffectTexture.World = camera.World; EffectTexture.View = camera.View; EffectTexture.Projection = camera.Projection; foreach (EffectPass pass in EffectTexture.CurrentTechnique.Passes) { pass.Apply(); foreach (RenderBoundaries<Ground> render in Boundaries.Where(m => frustum.Contains(m.Box) != ContainmentType.Disjoint)) { // Draw ground count++; } } return count; } When I try adding just one ground, then moving the camera so the ground is out of frame it still returns 1 which means it still gets draw even though it's not within the camera's view. Am I doing something or wrong or can it be because of my Camera? Any ideas why it doesn't work?

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• Top down space game control problem

  - by Phil

  As the title suggests I'm developing a top down space game. I'm not looking to use newtonian physics with the player controlled ship. I'm trying to achieve a control scheme somewhat similar to that of FlatSpace 2 (awesome game). I can't figure out how to achieve this feeling with keyboard controls as opposed to mouse controls though. Any suggestions? I'm using Unity3d and C# or javaScript (unityScript or whatever is the correct term) works fine if you want to drop some code examples. Edit: Of course I should describe FlatSpace 2's control scheme, sorry. You hold the mouse button down and move the mouse in the direction you want the ship to move in. But it's not the controls I don't know how to do but rather the feeling of a mix of driving a car and flying an aircraft. It's really well made. Youtube link: FlatSpace2 on iPhone I'm not developing an iPhone game but the video shows the principle of the movement style. Edit 2 As there seems to be a slight interest, I'll post the version of the code I've used to continue. It works good enough. Sometimes good enough is sufficient! using UnityEngine; using System.Collections; public class ShipMovement : MonoBehaviour { public float directionModifier; float shipRotationAngle; public float shipRotationSpeed = 0; public double thrustModifier; public double accelerationModifier; public double shipBaseAcceleration = 0; public Vector2 directionVector; public Vector2 accelerationVector = new Vector2(0,0); public Vector2 frictionVector = new Vector2(0,0); public int shipFriction = 0; public Vector2 shipSpeedVector; public Vector2 shipPositionVector; public Vector2 speedCap = new Vector2(0,0); void Update() { directionModifier = -Input.GetAxis("Horizontal"); shipRotationAngle += ( shipRotationSpeed * directionModifier ) * Time.deltaTime; thrustModifier = Input.GetAxis("Vertical"); accelerationModifier = ( ( shipBaseAcceleration * thrustModifier ) ) * Time.deltaTime; directionVector = new Vector2( Mathf.Cos(shipRotationAngle ), Mathf.Sin(shipRotationAngle) ); //accelerationVector = Vector2(directionVector.x * System.Convert.ToDouble(accelerationModifier), directionVector.y * System.Convert.ToDouble(accelerationModifier)); accelerationVector.x = directionVector.x * (float)accelerationModifier; accelerationVector.y = directionVector.y * (float)accelerationModifier; // Set friction based on how "floaty" controls you want shipSpeedVector.x *= 0.9f; //Use a variable here shipSpeedVector.y *= 0.9f; //<-- as well shipSpeedVector += accelerationVector; shipPositionVector += shipSpeedVector; gameObject.transform.position = new Vector3(shipPositionVector.x, 0, shipPositionVector.y); } }

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• Modify registry for Internet Connection Sharing?

  - by Tim

  My OS is Windows XP. Quoted from How to Change the IP Range for the Internet Connection Sharing DHCP service Use Registry Editor to modify the data value of the IntranetInfo value in the following registry key: Hkey_Local_Machine\System\CurrentControlSet\Services\ICSharing\Settings\General The first number listed is the IP address of the internal IP address of the Connection Sharing host. The second number is the subnet IP address separated by a comma. Enter the first IP address of the new range followed by the subnet mask, separated by a comma. (For example, 169.254.0.1,255.255.0.0.). Modify the data value of the Start value in the following registry key: Hkey_Local_Machine\System\CurrentControlSet\Services\ICSharing\Addressing\Settings Change the value to the second address of the selected IP range. This address cannot be the same or a lower value than the IP address used for the IntranetInfo key. Modify the data value for the Stop value in the same registry key. Enter the last the IP address of the selected IP range. My registry table does not have Hkey_Local_Machine\System\CurrentControlSet\Services\ICSharing, and I don't know how to do with my registry table following the above three steps. Can someone guide me through it step by step?

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• Openconnect for Cisco VPN doesn't recognize private key file - asn1 encoding routines:ASN1_CHECK_TLEN:wrong tag

  - by Alexander Skwar

  I'm trying to use my Synology DS212 NAS box also act as VPN gateway to my companies VPN. Sadly, they only use Cisco ASA and to complicate stuff even further, we've got to use personal certificates (which is of course more secure, but more complicate to get going…). So I compiled OpenConnect v4.06 from http://www.infradead.org/openconnect/. As a very basic test, I tried to build a connection by manually invoking openconnect, passing along the key and cert files, like so: /lib/ld-linux.so.3 --library-path /opt/lib \ /opt/openconnect/sbin/openconnect \ --certificate=$VPN_CFG/alexander.crt \ --sslkey=$VPN_CFG/alexander.key \ --cafile=$VPN_CFG/Company_VPN_CA.crt \ --user=alexander --verbose <ip>:443 It fails :( Attempting to connect to <ip>:443 Using certificate file $VPN_CFG/alexander.crt Using client certificate '/[email protected]/OU=Company VPN' 5919:error:0D0680A8:asn1 encoding routines:ASN1_CHECK_TLEN:wrong tag:tasn_dec.c:1315: Loading private key failed (see above errors) Loading certificate failed. Aborting. Failed to open HTTPS connection to <ip> Failed to obtain WebVPN cookie When I run the same command with the same cert/key files on a Ubuntu 12.04 box, it works: openconnect \ --certificate=$VPN_CFG/alexander.crt \ --sslkey=$VPN_CFG/alexander.key \ --cafile=$VPN_CFG/Company_VPN_CA.crt \ --user=alexander --verbose <ip>:443 Attempting to connect to <ip>:443 Using certificate file $VPN_CFG/alexander.crt Extra cert from cafile: '/CN=Company AG VPN CA/O=Company AG/L=Zurich/ST=ZH/C=CH' SSL negotiation with <ip> Server certificate verify failed: self signed certificate Certificate from VPN server "<ip>" failed verification. Reason: self signed certificate Enter 'yes' to accept, 'no' to abort; anything else to view: yes Connected to HTTPS on <ip> GET https://<ip>/ […] Well… The error on the NAS is this: 5919:error:0D0680A8:asn1 encoding routines:ASN1_CHECK_TLEN:wrong tag:tasn_dec.c:1315: Any ideas, what's causing this? On Syno, I use OpenConnect 4.06. On Ubuntu, I just compiled and installed to a custom location OpenConnect 4.06 as well. Thanks, Alexander

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• missing network usage through iptables

  - by Purres

  I inserted a rule to iptables to track the input usage to a certain ip address. The vps server's IP is 192.168.1.5 and the guest os's IP is 192.168.1.115. I ran 'yum update' inside the guest OS to get some network traffic. Then I ran iptables -vnL from the hypervisor. However it only showed network usage to the host, but not to the guest. Chain INPUT (policy ACCEPT 0 packets, 0 bytes) pkts bytes target source destination 0 0 0.0.0.0/0 0.0.0.0/0 destination IP range 192.168.1.115-192.168.1.115 1853 114K 0.0.0.0/0 0.0.0.0/0 destination IP range 192.168.1.5-192.168.1.5 I ran tcpdump and the log showed that there're data packets to the guest os. 16:17:43.932514 IP mirrordenver.fdcservers.net.http > 192.168.1.115.34471: Flags [.], seq 17694667:17696115, ack 1345, win 113, options [nop,nop,TS val 1060308643 ecr 1958781], length 1448 16:17:43.932559 IP 192.168.1.115.34471 > mirrordenver.fdcservers.net.http: Flags [.], ack 17696115, win 15287, options [nop,nop,TS val 1958869 ecr 1060308643], length 0 Why the guest OS network usage couldn't be tracked? iptables -L will return the INPUT chain as following: Chain INPUT (policy ACCEPT) target prot opt source destination all -- anywhere anywhere destination IP range 192.168.1.115-192.168.1.115 all -- anywhere anywhere destination IP range 192.168.1.5-192.168.1.5 all -- anywhere anywhere

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• Bash Script - Traffic Shaping

  - by Craig-Aaron

  hey all, I was wondering if you could have a look at my script and help me add a few things to it, How do I get it to find how many active ethernet ports I have? and how do I filter more than 1 ethernet port How I get this to do a range of IP address? Once I have a few ethenet ports I need to add traffic control to each one #!/bin/bash # Name of the traffic control command. TC=/sbin/tc # The network interface we're planning on limiting bandwidth. IF=eth0 # Network card interface # Download limit (in mega bits) DNLD=10mbit # DOWNLOAD Limit # Upload limit (in mega bits) UPLD=1mbit # UPLOAD Limit # IP address range of the machine we are controlling IP=192.168.0.1 # Host IP # Filter options for limiting the intended interface. U32="$TC filter add dev $IF protocol ip parent 1:0 prio 1 u32" start() { # Hierarchical Token Bucket (HTB) to shape bandwidth $TC qdisc add dev $IF root handle 1: htb default 30 #Creates the root schedlar $TC class add dev $IF parent 1: classid 1:1 htb rate $DNLD #Creates a child schedlar to shape download $TC class add dev $IF parent 1: classid 1:2 htb rate $UPLD #Creates a child schedlar to shape upload $U32 match ip dst $IP/24 flowid 1:1 #Filter to match the interface, limit download speed $U32 match ip src $IP/24 flowid 1:2 #Filter to match the interface, limit upload speed } stop() { # Stop the bandwidth shaping. $TC qdisc del dev $IF root } restart() { # Self-explanatory. stop sleep 1 start } show() { # Display status of traffic control status. $TC -s qdisc ls dev $IF } case "$1" in start) echo -n "Starting bandwidth shaping: " start echo "done" ;; stop) echo -n "Stopping bandwidth shaping: " stop echo "done" ;; restart) echo -n "Restarting bandwidth shaping: " restart echo "done" ;; show) echo "Bandwidth shaping status for $IF:" show echo "" ;; *) pwd=$(pwd) echo "Usage: tc.bash {start|stop|restart|show}" ;; esac exit 0 thanks

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