Q. Explain the differences between Server-side and Client-side code?
A. Server-side code executes on the server. Client-side code executes in the context of the clients' browser.
Q. What are some ways to manage state in an ASP.Net application?
A. Session objects, Application objects, ViewState, cookies, hidden form fields.
Q. What does the "EnableViewState" property do? Why would I want it on or off?
A. It allows page objects to save their state in a Base64 encoded string in the page HTML. One should only have it enabled when needed because it adds to the page size and can get fairly large for complex pages with many controls. (It takes longer to download the page).
Q. What is the difference between Server.Transfer and Response.Redirect? Why would I choose one over the other?
A. Server.Transfer transfers excution directly to another page. Response.Redirect sends a response to the client and directs the client (the browser) to load the new page (it causes a roundtrip). If you don't need to execute code on the client, Transfer is more efficient.
Q. How can I maintain Session state in a Web Farm or
A. Use a State Server or SQL Server to store the session state.
Q. What base class do all Web Forms inherit from?
A. The Page class.
Q. What does WSDL stand for? What does it do?
A.(Web Services Description Language). It describes the interfaces and other information of a web service.
Q. Which WebForm Validator control would you use if you needed to make sure the values in two different WebForm controls matched?
A. CompareValidator Control
Q. What property must you set, and what method must you call in your code, in order to bind the data from some data source to the Repeater control?
A. You must set the DataSource property and call the DataBind method.
C# Questions
Q. Can you explain what inheritance is and an example of when you might use it?
A. Inheritance allows us to extend the functionality of a base class. It is an "Is a" type of relationship rather than a "Uses" type of relationship (a dalmation IS A dog which IS A canine which IS A mammal - dalmations inherist from dog which inherits from canine which inherits from mammal). All child classes retain the properties and methods of their parent classes but may override them. When you want to inherit (use the functionality of) another class. Base Class Employee. A Manager class could be derived from the Employee base class.
Q. Does C# support multiple-inheritance?
A. No, use interfaces instead.
Q. Can you prevent your class from being inherited by another class?
A. Yes. The keyword “sealed” will prevent the class from being inherited.
Q. What does the keyword “virtual” declare for a method or property?
A. The method or property can be overridden.
Q. What's the top .NET class that everything is derived from?
A. System.Object.
Q. What does it mean that a String is immutable?
A. Strings cannot be altered. When you alter a string (by adding to it for example), you are actually creating a new string.
Q. If I have to alter a string many times, such as mutliple concatenations, what class should I use?
A. StringBuilder. It is not immutable and is very efficient.
Q. In a Try - Catch - Finally block, will the finally block execute if an exception has not occurred? If an Exception has occurred?
A. Yes and yes.
Q. Whats MSIL, and why should developers need an appreciation of it, if at all?
A. MSIL is the Microsoft Intermediate Language. All .NET compatible languages will get converted to MSIL.
Q. Explain the three tier or n-Tier model.
A. Presentation (UI), business (logic and underlying code) and data (from storage or other sources).
Q. What is SOA?
A. Service Oriented Architecture. In SOA you create an abstract layer that your applications use to access various "services" and can aggregate the services. These services could be databases, web services, message queues or other sources. The Service Layer provides a way to access these services that the applications do not need to know how the access is done. For example, to get a full customer record, I might need to get data from a SGL Server database, a web service and a message queue. The Service layer hides this from the calling application. All the application knows is that it asked for a full customer record. It doesn't know what system or systems it came from or how it was retrieved.
Q. What is the role of the DataReader class in ADO.NET connections?
A. It returns a forward-only, read-only view of data from the data source when the command is executed.
Q. Is XML case-sensitive?
A. Yes.
Q. What is the CLR?
A. Common Language Runtime
Q. Can you explain some differences between an ADO.NET Dataset and an
A. A DataSet can represent an entire relational database in memory, complete with tables, relations, and views. A DataSet is designed to work without any continuing connection to the original data source. Data in a DataSet is bulk-loaded, rather than being loaded on demand. There's no concept of cursor types in a DataSet. DataSets have no current record pointer You can use For Each loops to move through the data. You can store many edits in a DataSet, and write them to the original data source in a single operation. Though the DataSet is universal, other objects in ADO.NET come in different versions for different data sources
Q. Name some of the Microsoft Application Blocks. Have you used any? Which ones?
A. Examples:
Exception Management
Logging
Data Access
User Interface
Caching Application Block for .NET
Asynchronous Invocation Application Block for .NET
Configuration Management Application Block for .NET
(there are others) We use Exception and Data Access
1. What’s a Windows process?
It’s an application that’s running and had been allocated memory.
2. What’s typical about a Windows process in regards to memory allocation?
Each process is allocated its own block of available RAM space, no process can access another process’ code or data. If the process crashes, it dies alone without taking the entire OS or a bunch of other applications down.
3. Explain what relationship is between a Process, Application Domain, and Application?
A process is an instance of a running application. An application is an executable on the hard drive or network. There can be numerous processes launched of the same application (5 copies of Word running), but 1 process can run just 1 application.
4. What are possible implementations of distributed applications in .NET?
.NET Remoting and ASP.NET Web Services. If we talk about the Framework Class Library, noteworthy classes are in System.Runtime.Remoting and System.Web.Services.
5. What are the consideration in deciding to use .NET Remoting or ASP.NET Web Services?
Remoting is a more efficient communication exchange when you can control both ends of the application involved in the communication process. Web Services provide an open-protocol-based exchange of informaion. Web Services are best when you need to communicate with an external organization or another (non-.NET) technology.
6. What’s a proxy of the server object in .NET Remoting?
It’s a fake copy of the server object that resides on the client side and behaves as if it was the server. It handles the communication between real server object and the client object. This process is also known as marshaling.
7. What are remotable objects in .NET Remoting?
Remotable objects are the objects that can be marshaled across the application domains. You can marshal by value, where a deep copy of the object is created and then passed to the receiver. You can also marshal by reference, where just a reference to an existing object is passed.
8. What are channels in .NET Remoting?
Channels represent the objects that transfer the other serialized objects from one application domain to another and from one computer to another, as well as one process to another on the same box. A channel must exist before an object can be transferred.
9. What security measures exist for .NET Remoting in System.Runtime.Remoting?
None. Security should be taken care of at the application level. Cryptography and other security techniques can be applied at application or server level.
10. What is a formatter?
A formatter is an object that is responsible for encoding and serializing data into messages on one end, and deserializing and decoding messages into data on the other end.
11. Choosing between HTTP and TCP for protocols and Binary and SOAP for formatters, what are the trade-offs?
Binary over TCP is the most effiecient, SOAP over HTTP is the most interoperable.
12. What’s SingleCall activation mode used for?
If the server object is instantiated for responding to just one single request, the request should be made in SingleCall mode.
13. What’s Singleton activation mode?
A single object is instantiated regardless of the number of clients accessing it. Lifetime of this object is determined by lifetime lease.
14. How do you define the lease of the object?
By implementing ILease interface when writing the class code.
15. Can you configure a .NET Remoting object via XML file?
Yes, via machine.config and application level .config file (or web.config in ASP.NET). Application-level XML settings take precedence over machine.config.
- How can you automatically generate interface for the remotable object in .NET with Microsoft tools?
Use the Soapsuds tool.
What is view state and use of it?
The current property settings of an ASP.NET page and those of any ASP.NET server controls contained within the page. ASP.NET can detect when a form is requested for the first time versus when the form is posted (sent to the server), which allows you to program accordingly.
What are user controls and custom controls?
Custom controls:
A control authored by a user or a third-party software vendor that does not belong to the .NET Framework class library. This is a generic term that includes user controls. A custom server control is used in Web Forms (ASP.NET pages). A custom client control is used in Windows Forms applications.
User Controls:
In ASP.NET: A user-authored server control that enables an ASP.NET page to be re-used as a server control. An ASP.NET user control is authored declaratively and persisted as a text file with an .ascx extension. The ASP.NET page framework compiles a user control on the fly to a class that derives from the System.Web.UI.UserControl class.
What are the validation controls?
A set of server controls included with ASP.NET that test user input in HTML and Web server controls for programmer-defined requirements. Validation controls perform input checking in server code. If the user is working with a browser that supports DHTML, the validation controls can also perform validation using client script.
What's the difference between Response.Write() andResponse.Output.Write()?
The latter one allows you to write formattedoutput.
What methods are fired during the page load? Init()
When the page is instantiated, Load() - when the page is loaded into server memory,PreRender () - the brief moment before the page is displayed to the user as HTML, Unload() - when page finishes loading.
Where does the Web page belong in the .NET Framework class hierarchy?
System.Web.UI.Page
Where do you store the information about the user's locale?
System.Web.UI.Page.Culture
What's the difference between Codebehind="MyCode.aspx.cs" and Src="MyCode.aspx.cs"?
CodeBehind is relevant to Visual Studio.NET only.
What's a bubbled event?
When you have a complex control, likeDataGrid, writing an event processing routine for each object (cell, button,row, etc.) is quite tedious. The controls can bubble up their eventhandlers, allowing the main DataGrid event handler to take care of its constituents.
Suppose you want a certain ASP.NET function executed on MouseOver over a certain button.
Where do you add an event handler?
It's the Attributesproperty, the Add function inside that property.
e.g. btnSubmit.Attributes.Add("onMouseOver","someClientCode();")
What data type does the RangeValidator control support?
Integer,String and Date.
What are the different types of caching?
Caching is a technique widely used in computing to increase performance by keeping frequently accessed or expensive data in memory. In context of web application, caching is used to retain the pages or data across HTTP requests and reuse them without the expense of recreating them.ASP.NET has 3 kinds of caching strategiesOutput CachingFragment CachingData
CachingOutput Caching: Caches the dynamic output generated by a request. Some times it is useful to cache the output of a website even for a minute, which will result in a better performance. For caching the whole page the page should have OutputCache directive.<%@ OutputCache Duration="60" VaryByParam="state" %>
Fragment Caching: Caches the portion of the page generated by the request. Some times it is not practical to cache the entire page, in such cases we can cache a portion of page<%@ OutputCache Duration="120" VaryByParam="CategoryID;SelectedID"%>
Data Caching: Caches the objects programmatically. For data caching asp.net provides a cache object for eg: cache["States"] = dsStates;
What do you mean by authentication and authorization?
Authentication is the process of validating a user on the credentials (username and password) and authorization performs after authentication. After Authentication a user will be verified for performing the various tasks, It access is limited it is known as authorization.
What are different types of directives in .NET?
@Page: Defines page-specific attributes used by the ASP.NET page parser and compiler. Can be included only in .aspx files <%@ Page AspCompat="TRUE" language="C#" %>
@Control:Defines control-specific attributes used by the ASP.NET page parser and compiler. Can be included only in .ascx files. <%@ Control Language="VB" EnableViewState="false" %>
@Import: Explicitly imports a namespace into a page or user control. The Import directive cannot have more than one namespace attribute. To import multiple namespaces, use multiple @Import directives. <% @ Import Namespace="System.web" %>
@Implements: Indicates that the current page or user control implements the specified .NET framework interface.<%@ Implements Interface="System.Web.UI.IPostBackEventHandler" %>
@Register: Associates aliases with namespaces and class names for concise notation in custom server control syntax.<%@ Register Tagprefix="Acme" Tagname="AdRotator" Src="AdRotator.ascx" %>
@Assembly: Links an assembly to the current page during compilation, making all the assembly's classes and interfaces available for use on the page. <%@ Assembly Name="MyAssembly" %><%@ Assembly Src="MySource.vb" %>
@OutputCache: Declaratively controls the output caching policies of an ASP.NET page or a user control contained in a page<%@ OutputCache Duration="#ofseconds" Location="Any | Client | Downstream | Server | None" Shared="True | False" VaryByControl="controlname" VaryByCustom="browser | customstring" VaryByHeader="headers" VaryByParam="parametername" %>
@Reference: Declaratively indicates that another user control or page source file should be dynamically compiled and linked against the page in which this directive is declared.
How do I debug an ASP.NET application that wasn't written with Visual Studio.NET and that doesn't use code-behind?
Start the DbgClr debugger that comes with the .NET Framework SDK, open the file containing the code you want to debug, and set your breakpoints. Start the ASP.NET application. Go back to DbgClr, choose Debug Processes from the Tools menu, and select aspnet_wp.exe from the list of processes. (If aspnet_wp.exe doesn't appear in the list,check the "Show system processes" box.) Click the Attach button to attach to aspnet_wp.exe and begin debugging.
Be sure to enable debugging in the ASPX file before debugging it with DbgClr. You can enable tell ASP.NET to build debug executables by placing a
<%@ Page Debug="true" %> statement at the top of an ASPX file or a
No. The
RegisterClientScriptBlock is for returning blocks of client-side script containing functions. RegisterStartupScript is for returning blocks of client-script not packaged in functions-in other words, code that's to execute when the page is loaded. The latter positions script blocks near the end of the document so elements on the page that the script interacts are loaded before the script runs.<%@ Reference Control="MyControl.ascx" %>
WEB SERVICES
What platforms do .NET XML Web Services run on?
Currently, they're supported on Windows 2000 and Windows XP. ASP.NET integrates with Internet Information Server (IIS) and thus requires that IIS be installed. It runs on server and non-server editions of Windows 2000 and XP as long as IIS is
installed.
Can two different programming languages be mixed in a single ASMX file?
No.
What is code-behind?
Code-behind allows you to associate Web Service source code written in a CLR compliant language (such as C# or VB.NET) as compiled in a separate file (typically *.asmx.cs or *.asmx.vb). You would otherwise typically find the executable code directly inserted into the .asmx file.
What namespaces are imported by default in ASMX files?
The following namespaces are imported by default. Other namespaces must be imported manually.· System, System.Collections,System.ComponentModel,System.Data, System.Diagnostics,System.Web,System.Web.Services
How do I provide information to the Web Service when the information is required as a SOAP Header?
The key here is the Web Service proxy you created using wsdl.exe or through Visual Studio .NET's Add Web Reference menu option. If you happen to download a WSDL file for a Web Service that requires a SOAP header, .NET will create a SoapHeader class in the proxy source file. Using the previous example:
public class Service1 : System.Web.Services.Protocols.SoapHttpClientProtocol
{
public AuthToken AuthTokenValue;
[System.Xml.Serialization.XmlRootAttribute(Namespace="http://tempuri.org/", IsNullable=false)]
public class AuthToken : SoapHeader { public string Token; }}
In this case, when you create an instance of the proxy in your main application file, you'll also create an instance of the AuthToken class and assign the string:
Service1 objSvc = new Service1();
processingobjSvc.AuthTokenValue = new AuthToken();
objSvc.AuthTokenValue.Token =
Web Servicestring strResult = objSvc.MyBillableWebMethod();
What is WSDL?
WSDL is the Web Service Description Language, and it is implemented as a specific XML vocabulary. While it's very much more complex than what can be described here, there are two important aspects to WSDL with which you should be aware. First, WSDL provides instructions to consumers of Web Services to describe the layout and contents of the SOAP packets the Web Service intends to issue. It's an interface description document, of sorts. And second, it isn't intended that you read and interpret the WSDL. Rather, WSDL should be processed by machine, typically to generate proxy source code (.NET) or create dynamic proxies on the fly (the SOAP Toolkit or Web Service Behavior).
When was .NET announced?
Bill Gates delivered a keynote at Forum 2000, held
When was the first version of .NET released?
The final version of the 1.0 SDK and runtime was made publicly available around
What platforms does the .NET Framework run on?
The runtime supports Windows XP, Windows 2000, NT4 SP6a and Windows ME/98. Windows 95 is not supported. Some parts of the framework do not work on all platforms - for example, ASP.NET is only supported on Windows XP and Windows 2000. Windows 98/ME cannot be used for development.
IIS is not supported on Windows XP Home Edition, and so cannot be used to host ASP.NET. However, the ASP.NET Web Matrix
web server does run on XP Home.
The Mono project is attempting to implement the .NET framework on Linux.
What is the CLR?
CLR = Common Language Runtime. The CLR is a set of standard resources that (in theory) any .NET program can take advantage of, regardless of programming language. Robert Schmidt (Microsoft) lists the following CLR resources in his MSDN PDC# article:
Object-oriented programming model (inheritance, polymorphism, exception handling, garbage collection)
Security model
Type system
All .NET base classes
Many .NET framework classes
Development, debugging, and profiling tools
Execution and code management
IL-to-native translators and optimizers
What this means is that in the .NET world, different programming languages will be more equal in capability than they have ever been before, although clearly not all languages will support all CLR services.
What is the CTS?
CTS = Common Type System. This is the range of types that the .NET runtime understands, and therefore that .NET applications can use. However note that not all .NET languages will support all the types in the CTS. The CTS is a superset of the CLS.
What is the CLS?
CLS = Common Language Specification. This is a subset of the CTS which all .NET languages are expected to support. The idea is that any program which uses CLS-compliant types can interoperate with any .NET program written in any language.
In theory this allows very tight interop between different .NET languages - for example allowing a C# class to inherit from a VB class.
What is IL?
IL = Intermediate Language. Also known as MSIL (Microsoft Intermediate Language) or CIL (Common Intermediate Language). All .NET source code (of any language) is compiled to IL. The IL is then converted to machine code at the point where the software is installed, or at run-time by a Just-In-Time (JIT) compiler.
What does 'managed' mean in the .NET context?
The term 'managed' is the cause of much confusion. It is used in various places within .NET, meaning slightly different things.Managed code: The .NET framework provides several core run-time services to the programs that run within it - for example
exception handling and security. For these services to work, the code must provide a minimum level of information to the runtime.
Such code is called managed code. All C# and Visual Basic.NET code is managed by default. VS7 C++ code is not managed by default, but the compiler can produce managed code by specifying a command-line switch (/com+).
Managed data: This is data that is allocated and de-allocated by the .NET runtime's garbage collector. C# and VB.NET data is always managed. VS7 C++ data is unmanaged by default, even when using the /com+ switch, but it can be marked as managed using the __gc keyword.Managed classes: This is usually referred to in the context of Managed Extensions (ME) for C++. When using ME C++, a class can be marked with the __gc keyword. As the name suggests, this means that the memory for instances of the class is managed by the garbage collector, but it also means more than that. The class becomes a fully paid-up member of the .NET community with the benefits and restrictions that brings. An example of a benefit is proper interop with classes written in other languages - for example, a managed C++ class can inherit from a VB class. An example of a restriction is that a managed class can only inherit from one base class.
What is reflection?
All .NET compilers produce metadata about the types defined in the modules they produce. This metadata is packaged along with the module (modules in turn are packaged together in assemblies), and can be accessed by a mechanism called reflection. The System.Reflection namespace contains classes that can be used to interrogate the types for a module/assembly.
Using reflection to access .NET metadata is very similar to using ITypeLib/ITypeInfo to access type library data in COM, and it is used for similar purposes - e.g. determining data type sizes for marshaling data across context/process/machine boundaries.
Reflection can also be used to dynamically invoke methods (see System.Type.InvokeMember ) , or even create types dynamically at run-time (see System.Reflection.Emit.TypeBuilder).
What is the difference between Finalize and Dispose (Garbage collection) ?
Class instances often encapsulate control over resources that are not managed by the runtime, such as window handles (HWND), database connections, and so on. Therefore, you should provide both an explicit and an implicit way to free those resources. Provide implicit control by implementing the protected Finalize Method on an object (destructor syntax in C# and the Managed Extensions for C++). The garbage collector calls this method at some point after there are no longer any valid references to the object. In some cases, you might want to provide programmers using an object with the ability to explicitly release these external resources before the garbage collector frees the object. If an external resource is scarce or expensive, better performance can be achieved if the programmer explicitly releases resources when they are no longer being used. To provide explicit control, implement the Dispose method provided by the IDisposable Interface. The consumer of the object should call this method when it is done using the object.
Dispose can be called even if other references to the object are alive. Note that even when you provide explicit control by way of Dispose, you should provide implicit cleanup using the Finalize method. Finalize provides a backup to prevent resources from
permanently leaking if the programmer fails to call Dispose.
What is Partial Assembly References?
Full Assembly reference: A full assembly reference includes the assembly's text name, version, culture, and public key token (if the assembly has a strong name). A full assembly reference is required if you reference any assembly that is part of the common
language runtime or any assembly located in the global assembly cache.
Partial Assembly reference: We can dynamically reference an assembly by providing only partial information, such as specifying only the assembly name. When you specify a partial assembly reference, the runtime looks for the assembly only in the application
directory.
We can make partial references to an assembly in your code one of the following ways:
-> Use a method such as System.Reflection.Assembly.Load and specify only a partial reference. The runtime checks for the assembly in the application directory.
-> Use the System.Reflection.Assembly.LoadWithPartialName method and specify only a partial reference. The runtime checks for the assembly in the application directory and in the global assembly cache
Changes to which portion of version number indicates an incompatible change?
Major or minor. Changes to the major or minor portion of the version number indicate an incompatible change. Under this convention then, version 2.0.0.0 would be considered incompatible with version 1.0.0.0. Examples of an incompatible change would be a change to the types of some method parameters or the removal of a type or method altogether. Build. The Build number is typically used to distinguish between daily builds or smaller compatible releases. Revision. Changes to the revision number are typically reserved for an incremental build needed to fix a particular bug. You'll sometimes hear this referred to as the "emergency bug fix" number in that the revision is what is often changed when a fix to a specific bug is shipped to a customer.
What distributed process frameworks outside .NET do you know?
Distributed Computing Environment/Remote Procedure Calls (DEC/RPC), Microsoft Distributed Component Object Model (DCOM), Common Object Request Broker Architecture (CORBA), and Java Remote Method Invocation (RMI).
What are possible implementations of distributed applications in .NET?
.NET Remoting and ASP.NET Web Services. If we talk about the Framework Class Library, noteworthy classes are in System.Runtime.Remoting and System.Web.Services.
When would you use .NET Remoting and when Web services?
Use remoting for more efficient exchange of information when you control both ends of the application. Use Web services for open-protocol-based information exchange when you are just a client or a server with the other end belonging to someone else.
What's a proxy of the server object in .NET Remoting?
It's a fake copy of the server object that resides on the client side and behaves as if it was the server. It handles the communication between real server object and the client object. This process is also known as marshaling.
What are remotable objects in .NET Remoting?
Remotable objects are the objects that can be marshaled across the application domains. You can marshal by value, where a deep copy of the object is created and then passed to the receiver. You can also marshal by reference, where just a reference to an existing object is passed.
What are channels in .NET Remoting?
Channels represent the objects that transfer the other serialized objects from one application domain to another and from one computer to another, as well as one process to another on the same box. A channel must exist before an object can be transferred.
What security measures exist for .NET Remoting in System.Runtime.Remoting?
None. Security should be taken care of at the application level. Cryptography and other security techniques can be applied at application or server level.
What is a formatter?
A formatter is an object that is responsible for encoding and serializing data into messages on one end, and deserializing and decoding messages into data on the other end.
Choosing between HTTP and TCP for protocols and Binary and SOAP for formatters, what are the trade-offs?
Binary over TCP is the most effiecient, SOAP over HTTP is the most interoperable.
What's SingleCall activation mode used for?
If the server object is instantiated for responding to just one single request, the request should be made in SingleCall mode.
What's Singleton activation mode?
A single object is instantiated regardless of the number of clients accessing it. Lifetime of this object is determined by lifetime lease.
How do you define the lease of the object?
By implementing ILease interface when writing the class code.
Can you configure a .NET Remoting object via XML file?
Yes, via machine.config and application level .config file (or web.config in ASP.NET). Application-level XML settings take precedence over machine.config.
How can you automatically generate interface for the remotable object in .NET with Microsoft tools?
Use the Soapsuds tool.
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