how to create qr code using vb.net Your First WPF Application in visual basic

Compose QRCode in visual basic Your First WPF Application

There are a couple of options for a component to vote on the outcome of a transaction from code. One is declarative and the other imperative. The declarative method is very easy. A method can be flagged with the AutoComplete attribute, and as long as the method body does not throw an exception, the method s vote will be to commit the transaction. The method must be coded such that if something goes wrong, an exception is thrown. If an exception is thrown by the database, it must be left to ascend the call stack, or be trapped, wrapped, and rethrown. Any violation of business rules that results in the method being unable to complete its work must also be handled by throwing an exception. (You can find this code in XActional.cs in the Serviced project.) [Transaction(TransactionOption.Required)] public class CustomerService { [AutoComplete(true)] public void IncreaseCreditLimit( int customerNum, double increaseAmount) { try { Customer cust = new Customer(customerNum); double max = cust.MaxAllowableCredit; double current = cust.CreditLimit; if (max < current + increaseAmount) { throw new Exception("Max Credit Limit Exceeded"); } cust.CreditLimit += increaseAmount; cust.Save(); } catch (Exception ex) { throw new Exception( "Attempt to increase limit failed", ex); } } } Notice the explicitly thrown exception captures the violation of a business rule. The try/ catch block traps and wraps the explicitly thrown exception, or any other exception that bubbles up the call stack from your calls into the Customer object. The other option is to explicitly vote on the transaction outcome from within the body of your method. In this case, you would omit the AutoComplete attribute, and use the ContextUtil properties to indicate the success or failure of the work that s been done.

Note You might wonder why I wrote It s not that dictionary-managed tablespaces are not supported in a

if (!Csla.Security.AuthorizationRulesManager.PrincipalRoleInList( principal, allow)) result = false; } else { var deny = Csla.Security.AuthorizationRules.GetDenyGetRoles(objectType); if (deny != null) { if (Csla.Security.AuthorizationRulesManager.PrincipalRoleInList( principal, deny)) result = false; } } return result; } The GetAllowGetRoles() and GetDenyGetRoles() methods are helper methods that retrieve the list of roles allowed and denied access to the get operation for the specified type: internal static List<string> GetAllowGetRoles(Type objectType) { var typeRules = ObjectAuthorizationRules.GetRoles(objectType); return typeRules.AllowGetRoles; } The PrincipalRoleInList() method loops through the list of roles to determine whether the current user is in any of the roles in the list. This method is just a simple loop, but it calls a private method named IsInRole() rather than calling the IsInRole() method on the current principal object. Here s the IsInRole() method: private static bool IsInRole(IPrincipal principal, string role) { if (mIsInRoleProvider == null) { string provider = ApplicationContext.IsInRoleProvider; if (string.IsNullOrEmpty(provider)) mIsInRoleProvider = IsInRoleDefault; else { string[] items = provider.Split(','); Type containingType = Type.GetType(items[0] + "," + items[1]); mIsInRoleProvider = (IsInRoleProvider)(Delegate.CreateDelegate( typeof(IsInRoleProvider), containingType, items[2])); } } return mIsInRoleProvider(principal, role); } This method abstracts the IsInRole() concept so it isn t necessarily tied to checking with the current principal object. If the application s config file contains an entry for an IsInRoleProvider() method, that method is used instead of the default. The config entry would go in the <appSettings> element and would look like this:

Imagine, for instance, that your page contains critical and dynamic information such as stock quotes or flight arrival information that needs to be updated on a regular basis. You can use the Timer control on your page to trigger updates to an UpdatePanel control, all without having to do any full-page refreshes.

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The CLR has a tool called the Garbage Collector (GC), which automatically manages memory. The GC automatically deletes objects from memory that your program will no longer access. The GC relieves the programmer of tasks that he or she has traditionally had to perform, such as deallocating memory and hunting for memory leaks. Hunting for memory leaks can be difficult and time-consuming, so this is no small feature.