Events use a publisher/subscriber model. What is that?

1 Answer

Answer :

Objects publish events to which other applications subscribe. When the publisher raises an event all subscribers to that event are notified.

Related questions

Description : Can a subscriber subscribe to more than one publisher?

Last Answer : Yes, also - here's some code for a publisher with multiple subscribers. using System; namespace Console1 { class Class1 { delegate void myDelegate(int parameter1); static event myDelegate myEvent; ... TimeEventArgs time) { Console.WriteLine("Subscriber2:" + time.instanceSeconds); } } }

Description : What si the difference between interface and abstractclass Select Answer:  1. interface contain only methods  2. we can't declare a variable for interface  3. interface contain only events  4. None  5. All

Last Answer : Ans : 2 The only Difference between Interface and Abstract class is we can declare a variable in abstract class but we can't declare in variable interface

Description : Are events synchronous of asynchronous? 

Last Answer : Asynchronous

Description : Can events have access to modifiers?

Last Answer : Yes, you can have access to modifiers in events. You can have events with the protected keyword, which will be accessible only to inherited classes. You can have private events only for objects in that class.

Description : Do events have return type?

Last Answer : No, events do not have a return type.

Description : Define what is events?

Last Answer : An event is a member that enables a class or object to provide notifications. An event is declared like a field except that the declaration includes an event keyword and the type must be a delegate type.

Description : Explain the three services model commonly know as a three-tier application.

Last Answer : Presentation (UI), Business (logic and underlying code) and Data (from storage or other sources).

Description : Explain the three services model commonly know as a three-tier application.

Last Answer : Presentation (UI), Business (logic and underlying code) and Data (from storage or other sources). 

Description :  ___ is a stateful communication model and server is aware of all open connection. A. Request-Response B. Publish-Subscriber C. Push-Pull D. Exclusive Pair

Last Answer : D. Exclusive Pair 

Description :  _____ is a bi-directional, fully duplex communication model that uses a persistent connection between client and server. A. Request-Response B. Publish-Subscriber C. Push-Pull D. Exclusive Pair

Last Answer : D. Exclusive Pair 

Description : Describe how to use code to retrieve resources at run time.

Last Answer : You must first create an instance of the ResourceManager class that is associated with the assembly that contains the desired resource. You can then use the GetString method to retrieve string resources or the GetObject method to retrieve object resources.

Description : Explain how to use the PrintPreviewDialog control to display a preview of a printed document before it is printed.

Last Answer : You display a preview of a printed document with the PrintPreviewDialog control by first setting the PrintDocument property of the PrintPreviewDialog instance to the PrintDocument you want to preview, then by calling the PrintPreviewDialog.Show command to display the dialog box. 

Description : Explain how to use the HelpProvider component to provide help for UI elements.

Last Answer : You can provide either a HelpString or a help topic for UI elements with the HelpProvider. The HelpProvider provides HelpString, HelpKeyWord, and HelpNavigator properties for each control on the form. If ... particular element is displayed when the element has the focus and the F1 key is pressed.

Description : Explain how to use the Begin and End methods on a Web Service to make an asynchronous method call.

Last Answer : Every public Web method on a Web Service can be called either synchronously or asynchronously. To make an asynchronous call to a Web method, you call the method named Begin, where is the name of ... returned by Begin. This will allow you to retrieve the actual data returned by the Web method.

Description : Briefly describe how to use the PrintDocument component to print a document. Discuss maintaining correct line spacing and multipage documents.

Last Answer : The PrintDocument class exposes the Print method, which raises the PrintPage event. Code to render printed items to the printer should be placed in the PrintPage event handler. The PrintPage event ... been printed, you must incorporate all logic for printing multiple pages into your event handler.

Description : In Visual Basic .NET or Visual C# programming, when would you use Structured Query Language (SQL)? How are they executed? 

Last Answer : ADO.NET handles most of the database communication for you behind-thescenes. You would only use SQL statements when generating ad-hoc queries for the database. You execute SQL statements by ... returning statements, such as DELETE, INSERT INTO, or UPDATE statements, use the ExecuteNonQuery method.

Description : Describe how to use a DataView to filter or sort data.

Last Answer : You can apply sort criteria to a DataView by setting the Sort property to the name of a column or columns to be sorted by. The data represented in a DataView object can be filtered by setting the RowFilter property to a valid filter expression.

Description : When would you use the Watch window? 

Last Answer : You would use the Watch window to observe the values of application variables while in Break mode.

Description : Explain why you might use enums and constants instead of their associated literal values.

Last Answer : Enums and constants make code easier to read and maintain by substituting human-legible tokens for frequently used constant values.

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Last Answer : Use the Imports keyword (Visual Basic .NET) or the using keyword (Visual C#) to make a .NET Framework namespace visible to your application. 

Description : Write code to use threading and the lock keyword. 

Last Answer : using System; using System.Threading; namespace ConsoleApplication4 { class Class1 { [STAThread] static void Main(string[] args) { ThreadClass tc1 = new ThreadClass(1); ThreadClass tc2 = new ThreadClass( ... Console.WriteLine(threadNumber + " working"); Thread.Sleep(1000); } } } } }

Description : Write code to define and use your own custom attribute.

Last Answer : (From MSDN) // cs_attributes_retr.cs using System; [AttributeUsage(AttributeTargets.Class|AttributeTargets.Struct, AllowMultiple=true)] public class Author : Attribute { public Author(string name) { this.name ... double version; string name; public string GetName() { return name; } }

Description : What keyword would you use for scope name clashes?

Last Answer : this

Description : What namespace would you use for reflection?

Last Answer : System.Reflection 

Description : Can nested classes use any of the 5 types of accessibility?

Last Answer : Yes

Description : Write some code to declare and use properties.

Last Answer : // instance public string InstancePr { get { return a; } set { a = value; } } //read-only static public static int ClassPr { get { return b; } }

Description : Write some code that declares an array on ints, assigns the values: 0,1,2,5,7,8,11 to that array and use a foreach to do something with those values.

Last Answer : int x = 0, y = 0; int[] arr = new int [] {0,1,2}; foreach (int i in arr) { if (i%2 == 0) x++; else y++; }

Description : Write some code to use a delegate. 

Last Answer : Member function with a parameter using System; namespace Console1 { class Class1 { delegate void myDelegate(int parameter1); static void Main(string[] args) { MyClass myInstance = new ... void AMethod(int param1) { Console.WriteLine(param1); } } }

Description : Can you use access modifiers with destructors? 

Last Answer : No

Description : Define what is the main use of delegates in C#?

Last Answer : Delegates are mainly used to define call back methods.

Description : Define what is the use of the return statement?

Last Answer : The return statement is associated with procedures (methods or functions). On executing the return statement, the system passes the control from the called procedure to the calling procedure. This ... the currently executed code to return some value to the caller of the currently executed code.

Description : Define what is the use of a goto statement?

Last Answer : The goto statement is also included in the C# language. This goto can be used to jump from inside a loop to outside. But jumping from outside to inside a loop is not allowed.

Description : Define what is the use of the abstract keyword?

Last Answer : The modifier abstract is a keyword used with a class, to indicate that this class cannot itself have direct instances or objects, and it is intended to be only a ‘base’ class to other classes.

Description : Can we use “this” inside a static method in C#?

Last Answer : No. We can’t use “this” in a static method.

Description : Why use “finally” block in C#?

Last Answer : Finally block will be executed irrespective of exception. So while executing the code in try block when an exception occurs, control is returned to catch block and at last finally block will be ... the closing connection to database / releasing the file handlers can be kept in finally block.

Description : Why use the keyword “const” in C#? Give an example.

Last Answer : “Const” keyword is used for making an entity constant. We can’t reassign the value to constant. Eg: const string _name = “Test”;

Description : Why use “using” in C#?

Last Answer : “Using” statement calls – “dispose of” method internally, whenever any exception occurred in any method call and in “Using” statement objects are read-only and cannot be reassignable or modifiable.

Description : What is the lifespan for items stored in ViewState? Select Answer:  1. Item stored in ViewState exist for the life of the current page  2. Item stored in ViewState exist for the life ... of the current Applicaiton  4. Item stored in ViewState exist for the life of the current configuration

Last Answer : 1. Item stored in ViewState exist for the life of the current page AS any web application works on request and response basis ,so on every post backs, The data in control gets lost. To retain page ... control with data. The life cycle of the view state exist for life of current running page only. 

Description : Which one of the following tools is used to view the metadata information contained in a .NET assembly? Select Answer:  1. al.exe  2. ilasm.exe  3. vbx.exe  4. csc.exe  5. ildasm.exe

Last Answer :  5. ildasm.exe

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Last Answer : You can ensure that registry entries are removed, as well as perform any other “clean-up” tasks, by creating an Installer class and writing the appropriate code in the Rollback event handler. Then create a new Custom Action and set the InstallerClass, and EntryPoint properties to appropriate values.

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Last Answer : First, create a file search to search the file system for the specific file. Then create a launch condition to evaluate the results of the search. You can connect the launch condition to ... in the search's Property property in the expression specified by the launch condition's Condition property. 

Description : What is the purpose of a bootstrapper application? When do you not need to create one?

Last Answer : A bootstrapper application automatically detects if Windows Installer is installed on the target machine. If Windows Installer is not present, it installs Windows Installer before proceeding with the rest ... Installer 1.5 already installed) or have had Microsoft Installer 1.5 installed previously.

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Last Answer : A native image is a precompiled version of a .NET assembly. You can create a native image of your application by using the Ngen.exe utility.

Description : Describe XCOPY deployment. Under what conditions is it useful? When can it not be used?

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Description : Briefly highlight the differences between imperative and declarative security as they pertain to code access security.

Last Answer : Imperative security is implemented by calling methods of Permission objects in code at run time. Declarative security is configured by attaching attributes representing permissions to classes ... request assembly-wide permissions using the Assembly (assembly) directive with declarative security.

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Description : Describe how to sign your assembly with a strong name. Why would you want to do this?

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Last Answer : Globalization refers to the application of culture-specific format to existing data. Localization refers to providing new culture-specific resources and retrieving the appropriate resources based on the culture setting. 

Description : Explain how to convert data in legacy code page formats to the Unicode format.

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