What is WCF?
Windows Communication Foundation (WCF) is an SDK for developing and deploying services on Windows. WCF provides a runtime environment for services, enabling you to expose CLR types as services, and to consume other services as CLR types. WCF is part of .NET 3.0 and requires .NET 2.0, so it can only run on systems that support it.
ABC is the three building blocks of WCF and they are known as
A - Address (Where): Address tells us where to find the services, like url B - Bindings (How) : Bindings tells us how to find the services or using which protocols finds the services (SOAP, HTTP, TCT etc.) C - Contacts (What): Contracts are an agreement between the consumer and the service providers that explains what parameters the service expects and what return values it gives. Hope this will be very helpful to understand three building blocks of WCF, a very frequently asked interview questions.
What is service and client in perspective of data communication?
A service is a unit of functionality exposed to the world.
The client of a service is merely the party consuming the service.
What is address in WCF and how many types of transport schemas are there in WCF?
Address is a way of letting client know that where a service is located. In WCF, every service is associated with a unique address. This contains the location of the service and transport schemas. WCF supports following transport schemas HTTP TCP Peer network IPC (Inter-Process Communication over named pipes) MSMQ
The sample address for above transport schema may look like
http://localhost:81 http://localhost:81/MyService net.tcp://localhost:82/MyService net.pipe://localhost/MyPipeService net.msmq://localhost/private/MyMsMqService net.msmq://localhost/MyMsMqService
What are contracts in WCF?
In WCF, all services expose contracts. The contract is a platform-neutral and standard way of describing what the service does. WCF defines four types of contracts. Service contracts Describe which operations the client can perform on the service. There are two types of Service Contracts. ServiceContract - This attribute is used to define the Interface. OperationContract - This attribute is used to define the method inside Interface. [ServiceContract]
interface IMyContract
{
[OperationContract]
string MyMethod( );
}
class MyService : IMyContract
{
public string MyMethod( )
{
return "Hello World";
}
}
Data contracts
Define which data types are passed to and from the service. WCF defines implicit contracts for built-in types such as int and string, but we can easily define explicit opt-in data contracts for custom types. There are two types of Data Contracts. DataContract - attribute used to define the class DataMember - attribute used to define the properties. [DataContract]
class Contact
{
[DataMember]
public string FirstName;
[DataMember]
public string LastName;
}
If DataMember attributes are not specified for a properties in the class, that property can't be passed to-from web service. Fault contracts Define which errors are raised by the service, and how the service handles and propagates errors to its clients. Message contracts Allow the service to interact directly with messages. Message contracts can be typed or untyped, and are useful in interoperability cases and when there is an existing message format we have to comply with.
Where we can host WCF services?
Every WCF services must be hosted somewhere. There are three ways of hosting WCF services. They are 1. IIS 2. Self Hosting 3. WAS (Windows Activation Service) For more details see http://msdn.microsoft.com/en-us/library/bb332338.aspx
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Sunday, 27 May 2012
FAQ's - WCF (Windows Communication Foundation)
Thursday, 24 May 2012
FAQ's - ASP.NET MVC
What are the 3 main components of an ASP.NET MVC application?
“ASP.NET MVC is the evolution of Classic ASP, adding an easier separation of concerns while not using an event based model like WebForms.”
1. M - Model
2. V - View
3. C - Controller
In which assembly is the MVC framework defined?
System.Web.Mvc
Is it possible to combine ASP.NET webforms and ASP.MVC and develop a single web application?
Yes, it is possible to combine ASP.NET webforms and ASP.MVC and develop a single web application.
What does Model, View and Controller represent in an MVC application?
Model: Model represents the application data domain. In short the applications business logic is contained with in the model.
View: Views represent the user interface, with which the end users interact. In short the all the user interface logic is contained with in the UI.
Controller: Controller is the component that responds to user actions. Based on the user actions, the respective controller, work with the model, and selects a view to render that displays the user interface. The user input logic is contained with in the controller.
What is the greatest advantage of using asp.net mvc over asp.net webforms?
It is difficult to unit test UI with webforms, where views in mvc can be very easily unit tested.
Which approach provides better support for test driven development - ASP.NET MVC or ASP.NET Webforms?
ASP.NET MVC
What are the advantages of ASP.NET MVC?
1. Extensive support for TDD. With asp.net MVC, views can also be very easily unit tested.
2. Complex applications can be easily managed
3. Seperation of concerns. Different aspects of the application can be divided into Model, View and Controller.
4. ASP.NET MVC views are light weight, as they donot use viewstate.
Is it possible to unit test an MVC application without running the controllers in an ASP.NET process?
Yes, all the features in an asp.net MVC application are interface based and hence mocking is much easier. So, we don't have to run the controllers in an ASP.NET process for unit testing.
Is it possible to share a view across multiple controllers?
Yes, put the view into the shared folder. This will automatically make the view available across multiple controllers.
What is the role of a controller in an MVC application?
The controller responds to user interactions, with the application, by selecting the action method to execute and alse selecting the view to render.
Where are the routing rules defined in an asp.net MVC application?
In Application_Start event in Global.asax
Name a few different return types of a controller action method?
The following are just a few return types of a controller action method. In general an action method can return an instance of a any class that derives from ActionResult class.
1. ViewResult
2. JavaScriptResult
3. RedirectResult
4. ContentResult
5. JsonResult
What is the significance of NonActionAttribute?
In general, all public methods of a controller class are treated as action methods. If you want prevent this default behaviour, just decorate the public method with NonActionAttribute.
What is the significance of ASP.NET routing?
ASP.NET MVC uses ASP.NET routing, to map incoming browser requests to controller action methods. ASP.NET Routing makes use of route table. Route table is created when your web application first starts. The route table is present in the Global.asax file.
What are the 3 segments of the default route, that is present in an ASP.NET MVC application?
1st Segment - Controller Name
2nd Segment - Action Method Name
3rd Segment - Parameter that is passed to the action method
Example: http://pragimtech.com/Customer/Details/5
Controller Name = Customer
Action Method Name = Details
Parameter Id = 5
ASP.NET MVC application, makes use of settings at 2 places for routing to work correctly. What are these 2 places?
1. Web.Config File : ASP.NET routing has to be enabled here.
2. Global.asax File : The Route table is created in the application Start event handler, of the Global.asax file.
What is the adavantage of using ASP.NET routing?
In an ASP.NET web application that does not make use of routing, an incoming browser request should map to a physical file. If the file does not exist, we get page not found error.
An ASP.NET web application that does make use of routing, makes use of URLs that do not have to map to specific files in a Web site. Because the URL does not have to map to a file, you can use URLs that are descriptive of the user's action and therefore are more easily understood by users.
What are the 3 things that are needed to specify a route?
1. URL Pattern - You can include placeholders in a URL pattern so that variable data can be passed to the request handler without requiring a query string.
2. Handler - The handler can be a physical file such as an .aspx file or a controller class.
3. Name for the Route - Name is optional.
Is the following route definition a valid route definition?
{controller}{action}/{id}
No, the above definition is not a valid route definition, because there is no literal value or delimiter between the placeholders. Therefore, routing cannot determine where to separate the value for the controller placeholder from the value for the action placeholder.
What is the use of the following default route?
{resource}.axd/{*pathInfo}
This route definition, prevent requests for the Web resource files such as WebResource.axd or ScriptResource.axd from being passed to a controller.
What is the difference between adding routes, to a webforms application and to an mvc application?
To add routes to a webforms application, we use MapPageRoute() method of the RouteCollection class, where as to add routes to an MVC application we use MapRoute() method.
How do you handle variable number of segments in a route definition?
Use a route with a catch-all parameter. An example is shown below. * is referred to as catch-all parameter.
controller/{action}/{*parametervalues}
Explain different return types in controllers?
What are the 2 ways of adding constraints to a route?
1. Use regular expressions
2. Use an object that implements IRouteConstraint interface
Give 2 examples for scenarios when routing is not applied?
1. A Physical File is Found that Matches the URL Pattern - This default behaviour can be overriden by setting the RouteExistingFiles property of the RouteCollection object to true.
2. Routing Is Explicitly Disabled for a URL Pattern - Use the RouteCollection.Ignore() method to prevent routing from handling certain requests.
“ASP.NET MVC is the evolution of Classic ASP, adding an easier separation of concerns while not using an event based model like WebForms.”
1. M - Model
2. V - View
3. C - Controller
In which assembly is the MVC framework defined?
System.Web.Mvc
Is it possible to combine ASP.NET webforms and ASP.MVC and develop a single web application?
Yes, it is possible to combine ASP.NET webforms and ASP.MVC and develop a single web application.
What does Model, View and Controller represent in an MVC application?
Model: Model represents the application data domain. In short the applications business logic is contained with in the model.
View: Views represent the user interface, with which the end users interact. In short the all the user interface logic is contained with in the UI.
Controller: Controller is the component that responds to user actions. Based on the user actions, the respective controller, work with the model, and selects a view to render that displays the user interface. The user input logic is contained with in the controller.
What is the greatest advantage of using asp.net mvc over asp.net webforms?
It is difficult to unit test UI with webforms, where views in mvc can be very easily unit tested.
Which approach provides better support for test driven development - ASP.NET MVC or ASP.NET Webforms?
ASP.NET MVC
What are the advantages of ASP.NET MVC?
1. Extensive support for TDD. With asp.net MVC, views can also be very easily unit tested.
2. Complex applications can be easily managed
3. Seperation of concerns. Different aspects of the application can be divided into Model, View and Controller.
4. ASP.NET MVC views are light weight, as they donot use viewstate.
Is it possible to unit test an MVC application without running the controllers in an ASP.NET process?
Yes, all the features in an asp.net MVC application are interface based and hence mocking is much easier. So, we don't have to run the controllers in an ASP.NET process for unit testing.
Is it possible to share a view across multiple controllers?
Yes, put the view into the shared folder. This will automatically make the view available across multiple controllers.
What is the role of a controller in an MVC application?
The controller responds to user interactions, with the application, by selecting the action method to execute and alse selecting the view to render.
Where are the routing rules defined in an asp.net MVC application?
In Application_Start event in Global.asax
Name a few different return types of a controller action method?
The following are just a few return types of a controller action method. In general an action method can return an instance of a any class that derives from ActionResult class.
1. ViewResult
2. JavaScriptResult
3. RedirectResult
4. ContentResult
5. JsonResult
What is the significance of NonActionAttribute?
In general, all public methods of a controller class are treated as action methods. If you want prevent this default behaviour, just decorate the public method with NonActionAttribute.
What is the significance of ASP.NET routing?
ASP.NET MVC uses ASP.NET routing, to map incoming browser requests to controller action methods. ASP.NET Routing makes use of route table. Route table is created when your web application first starts. The route table is present in the Global.asax file.
What are the 3 segments of the default route, that is present in an ASP.NET MVC application?
1st Segment - Controller Name
2nd Segment - Action Method Name
3rd Segment - Parameter that is passed to the action method
Example: http://pragimtech.com/Customer/Details/5
Controller Name = Customer
Action Method Name = Details
Parameter Id = 5
ASP.NET MVC application, makes use of settings at 2 places for routing to work correctly. What are these 2 places?
1. Web.Config File : ASP.NET routing has to be enabled here.
2. Global.asax File : The Route table is created in the application Start event handler, of the Global.asax file.
What is the adavantage of using ASP.NET routing?
In an ASP.NET web application that does not make use of routing, an incoming browser request should map to a physical file. If the file does not exist, we get page not found error.
An ASP.NET web application that does make use of routing, makes use of URLs that do not have to map to specific files in a Web site. Because the URL does not have to map to a file, you can use URLs that are descriptive of the user's action and therefore are more easily understood by users.
What are the 3 things that are needed to specify a route?
1. URL Pattern - You can include placeholders in a URL pattern so that variable data can be passed to the request handler without requiring a query string.
2. Handler - The handler can be a physical file such as an .aspx file or a controller class.
3. Name for the Route - Name is optional.
Is the following route definition a valid route definition?
{controller}{action}/{id}
No, the above definition is not a valid route definition, because there is no literal value or delimiter between the placeholders. Therefore, routing cannot determine where to separate the value for the controller placeholder from the value for the action placeholder.
What is the use of the following default route?
{resource}.axd/{*pathInfo}
This route definition, prevent requests for the Web resource files such as WebResource.axd or ScriptResource.axd from being passed to a controller.
What is the difference between adding routes, to a webforms application and to an mvc application?
To add routes to a webforms application, we use MapPageRoute() method of the RouteCollection class, where as to add routes to an MVC application we use MapRoute() method.
How do you handle variable number of segments in a route definition?
Use a route with a catch-all parameter. An example is shown below. * is referred to as catch-all parameter.
controller/{action}/{*parametervalues}
Explain different return types in controllers?
ActionResult is an abstract class that can have several subtypes:
a) ViewResult - Renders a specifed view to the response stream b) PartialViewResult - Renders a specifed partial view to the response stream c) EmptyResult - An empty response is returned d) RedirectResult - Performs an HTTP redirection to a specifed URL e) RedirectToRouteResult - Performs an HTTP redirection to a URL that is determined by the routing engine, based on given route data f) JsonResult - Serializes a given ViewData object to JSON format g) JavaScriptResult - Returns a piece of JavaScript code that can be executed on the client h) ContentResult - Writes content to the response stream without requiring a view i) FileContentResult - Returns a fle to the client j) FileStreamResult - Returns a fle to the client, which is provided by a Stream k) FilePathResult - Returns a fle to the client |
What are the 2 ways of adding constraints to a route?
1. Use regular expressions
2. Use an object that implements IRouteConstraint interface
Give 2 examples for scenarios when routing is not applied?
1. A Physical File is Found that Matches the URL Pattern - This default behaviour can be overriden by setting the RouteExistingFiles property of the RouteCollection object to true.
2. Routing Is Explicitly Disabled for a URL Pattern - Use the RouteCollection.Ignore() method to prevent routing from handling certain requests.
Difference Between ViewBag and ViewData in MVC 3?
View Data
|
View Bag
|
ViewData is a dictionary of objects that are accessible
using strings as keys. This means that we will write code like this:
|
ViewBag uses the dynamic feature that was added in to C#
4. It allows an object to dynamically have properties added to it. The code
we write using ViewBag will look like this:
|
In Controller
public ActionResult Index()
{ var softwareDevelopers = new List<string> { "Brendan Enrick", "Kevin Kuebler", "Todd Ropog" }; ViewData["softwareDevelopers"] = softwareDevelopers; return View(); }
In View
<ul>
@foreach (var developer in (List<string>)ViewData["softwareDevelopers"]) { <li> @developer li> } ul>
Notice that when we go to use out object on the view that
we have to cast it since the ViewData is storing everything as object. Also,
we need to be careful since we’re using magic strings to access these values.
|
In Controller
public ActionResult Index()
{ var softwareDevelopers = new List<string> { "Brendan Enrick", "Kevin Kuebler", "Todd Ropog" }; ViewBag.softwareDevelopers = softwareDevelopers; return View(); }
In View
<ul>
@foreach (var developer in ViewBag.softwareDevelopers) { <li> @developer li> } ul>
Notice here that we did not have to cast our object when
using the ViewBag. This is because the dynamic we used lets us know the type.
Keep in mind that these dynamics are as the
name suggest, dynamic, which means that you need to be careful as these are
basically magic properties instead of magic strings.
|
Difference Between ASP.NET WebForms and ASP.NET MVC?
ASP.NET WebForms
|
ASP.NET MVC
|
| Uses the ‘Page Controller’ pattern. Each page has a code-behind class that acts as a controller and is responsible for rendering the layout. | Uses the ‘Front Controller’ pattern. There is a single central controller for all pages to process web application requests and facilitates a rich routing architecture |
| Uses an architecture that combines the Controller (code behind) and the View (.aspx). Thus the Controller has a dependency on the View. Due to this, testing and maintainability becomes an issue. | ASP.NET MVC enforces a "separation of concerns". The Model does not know anything about the View. The View does not know there’s a Controller. This makes MVC applications easier to test and maintain |
| The View is called before the Controller. | Controller renders View based on actions as a result of the User Interactions on the UI. |
| At its core, you ‘cannot’ test your controller without instantiating a View. There are ways to get around it using tools. | At its core, ASP.NET MVC was designed to make test-driven development easier. You ‘can’ test your Controller without instantiating a View and carry out unit-tests without having to run the controllers in an ASP.NET process. |
| WebForms manage state by using view state and server-based controls. | ASP.NET MVC does not maintain state information by using view state |
| WebForms supports an event-driven programming style that is like Windows applications and is abstracted from the user. The State management is made transparent by using sessions, viewstate etc. In the process, the HTML output is not clean making it difficult to manage later. The ViewState also increases your page size. | In ASP.NET MVC, the output is clean and you have full control over the rendered HTML. The orientation is towards building standard compliant pages and provides full control over the behavior of an application. |
| Deep understanding of HTML, CSS and JavaScript is not required to a large extent since the WebForm model abstracts a lot of these details and provides automatic plumbing. While abstracting details to provide ease of use, sometimes a solution is overcomplicated, than it needs to be. | A thorough understanding of how HTML, CSS and JavaScript work together is required. The advantage is you can do a lot of jQuery and AJAX stuff in an efficient and simple manner than you would do in an ASP.NET application. |
| WebForms can drastically reduce time while building up intranet and internet applications that use a lot of controls (drag and drop model). Although this is true for development, a lot of time is spent later to code around limitations. | You lose the 'drag and drop' quick model of building your web applications. The focus is on control over the application behavior and test-driven development. The model is extensible and you do not have to spend time working around limitations. |
| Relatively simple to learn and pickup. Works very well for developers who initially have trouble with the HTTP/HTML model and are coming from a similar WinForms oriented event model. | There is a learning curve to understand the why, when and how of ASP.NET MVC. |
| Lesser amount of code is required to build webapps since a lot of components are integrated and provided out of the box. You can also use a lot of data controls provided out of the box that rely on ViewState. | Since the application tasks are separated into different components, amount of code required is more. Since ASP.NET MVC does not use ViewState, you cannot use Data controls like GridView, Repeater. |
| Works very well for small teams where focus is on rapid application development | Works well for large projects where focus in on testability and maintainability. |
Wednesday, 23 May 2012
FAQ's - JQuery
If you put jQuery in your CV, then beware, you should be able to answer following questions. Better you read on, and test yourself how much you can score.
1. What is jQuery & its significance? Why it is so popular?
jQuery is lightweight, client side script JavaScript library file that supports all browsers.JQuery is a fast and concise JavaScript Library that simplifies HTML document traversing, event handling, animating, and Ajax interactions for rapid web development. jQuery makes it easy to play with the DOM, add effects, and execute Ajax requests.
This helps developer to reduce lines of code while he/she program. For example huge code written in Java Script, can be done easily with JQuery in one or two lines as it uses pre compiled JavaScript library internally. For example To find a Div that have class xxx we can do this using custom JavaScript by looping through all DOM elements, Find Div element write if statement checking the class then write the code to manipulate cross browser. But this can be achieved using jQuery with 2 lines of code. jQuery is a fun library to use and play.
It is so popular due to the below 10 reasons.
Now the Client side development is fun using jQuery Agree or not ??
jQuery is lightweight, client side script JavaScript library file that supports all browsers.JQuery is a fast and concise JavaScript Library that simplifies HTML document traversing, event handling, animating, and Ajax interactions for rapid web development. jQuery makes it easy to play with the DOM, add effects, and execute Ajax requests.
This helps developer to reduce lines of code while he/she program. For example huge code written in Java Script, can be done easily with JQuery in one or two lines as it uses pre compiled JavaScript library internally. For example To find a Div that have class xxx we can do this using custom JavaScript by looping through all DOM elements, Find Div element write if statement checking the class then write the code to manipulate cross browser. But this can be achieved using jQuery with 2 lines of code. jQuery is a fun library to use and play.
It is so popular due to the below 10 reasons.
- Cross Browser Compatibility.
- Fast but micro Famework.The jQuery core library minified is only about 24KB in size, so it is very easily to include in any application and it is pretty fast as well.
- Easy to learn and flexible.
- It is well documented.
- Reuse of plug-ins across projects .These plug ins are extendable.
- Latest CSS Complaint.
- Microsoft, which now includes jQuery with its MVC framework and integrated to VS2010 with intellisense support .
- IBM, Netflix use jQuery. Nokia have adopted it. Google uses and hosts the jQuery library.
- Easy to find support since there is a large development community and variety of plug-ins.
- DOM manipulation with querying and chaining is Wonderful & Robust. It is simple, concise and clear enough.
Now the Client side development is fun using jQuery Agree or not ??
2. What is jQuery UI?
jQuery UI is a library which is built on top of JQuery library. It can be called as one of the JavaScript plug-in that allows to create animations, sortables list, draggle list . This is developed as separate JavaScript File. This can be downloaded from http://ui.jquery.com/download (ui.jQuery.js).
jQuery UI responsible for widgets, components , themes , advanced effects , animation and interaction mechanism that is UI related things.
Accordions, sliders, dialog boxes, date pickers, and more. All these are ready to be used right now.
jQuery UI can be used to build highly interactive web applications.
You need to include latest jQuery , UI Core and Flora theme style sheet to work with jQuery UI.
In addition to the above source files you may need to refer each of the component files like ui.draggable.js, ui.resizable.js, ui.accordian.js etc .
or you may will have to refer jquery.ui.all.js script that contains all component .js files . But do not refer all if you are not using . It is advised to refer only the required files. You can also build the custom download .js file by selecting the required widgets .
This is used for Resizing (resizable method is plugged in jQuery UI), Exploding or animations.
The following is an example code that uses jQuery UI.
Refer the script files.
jQuery UI is a library which is built on top of JQuery library. It can be called as one of the JavaScript plug-in that allows to create animations, sortables list, draggle list . This is developed as separate JavaScript File. This can be downloaded from http://ui.jquery.com/download (ui.jQuery.js).
jQuery UI responsible for widgets, components , themes , advanced effects , animation and interaction mechanism that is UI related things.
Accordions, sliders, dialog boxes, date pickers, and more. All these are ready to be used right now.
jQuery UI can be used to build highly interactive web applications.
You need to include latest jQuery , UI Core and Flora theme style sheet to work with jQuery UI.
In addition to the above source files you may need to refer each of the component files like ui.draggable.js, ui.resizable.js, ui.accordian.js etc .
or you may will have to refer jquery.ui.all.js script that contains all component .js files . But do not refer all if you are not using . It is advised to refer only the required files. You can also build the custom download .js file by selecting the required widgets .
This is used for Resizing (resizable method is plugged in jQuery UI), Exploding or animations.
The following is an example code that uses jQuery UI.
Refer the script files.
1."stylesheet" href="themes/flora/flora.all.css" type="text/css" media="screen" title="Flora (Default)"/>2.3.Refer the required Components
1.2.3.1.$(document).ready(function() {
2.$("#dragme").draggable();
3.$("#dragme-x").draggable({ axis: "x" });
4.$("#accordionDemo").accordion({ event: "mouseover" });
5.$("#dragme-resize").draggable().resizable();
6.})
jQuery UI future is hope to be expecting excited and positive.
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