Asp Net Web Services

Asp Net Web Services: Here are some web services interview questions which is very helpful in interviews. This great listing of interview questions provides a lot of information on Web Services Questions and Web Services Faqs. Not at all, instead of web services faqs and interview questions you can also learn how to use web services in asp net. If you need more web services faqs used in asp net you can also contact us for more info.
Question: Can you define basic element of WebServices and explain any one from them?
Answer: These are as follows SOAP, WSDL and UDDI. And I am explaining about the SOAP(Simple Object Access Protocol) it is a communication protocol it is for communication between application it is platform and language independent.It is based on XML and also help to get from Firwall.

Question: Explain functioning of Web Services Protocols ?
Answer: Http-Get:- This is standard protocol that helps client to communicate with server with HTTP.When client send a request to server via HTTP request and reuired parameter are attached with the querystring.Example:-
http://www.dotnetquestion.info/dotnet/interview.aspx?id=pervej&cast=munjal and we get the value from querystring.
Request.querystring("id")
Request.querystring("cast").

Http-Post:-This is same as Http-Get but the diffrence is that in place of sending parameters onto the URL information is send with HTTP request message with some extra information which contains Parameters and their values.This Protocols is limited to sending name/value pairs.
SOAP:-The only diffrence is that its relies on the XML as compares to Http-Get,Http-Post.SOAP can send not only the name/value pairs but also some complex object also as for example datatypes,class,objects.SOAP can also uses request/reponse model as Http-Get,Http-post but it is not limited to Request/Response it can also send types of message.Because its uses XML that is pure text so firewalls not created so much problem because its easily converted in to HTML. .

Question: Why do some web service classes derive from System.Web.WebServices while others do not ?
Answer: Those asp net Web Service classes which employ objects like Application, Session, Context, Server, and User have to derive from System.Web.WebServices. If it does not use these objects, it is not necessary to be derived from it.



Question: What is WSDL ?
Answer: WSDL is an XML format for describing network services as a set of endpoints operating on messages containing either document-oriented or procedure-oriented information. The operations and messages are described abstractly, and then bound to a concrete network protocol and message format to define an endpoint. Related concrete endpoints are combined into abstract endpoints (services). (Source: www.w3.org).

Question: What is the standard you use to wrap up a call to a Web service ?
Answer: HTTP with SOAP.

Question: What is Asp Net Web Services ?
Answer: Web services are programmable business logic components that provide access to functionality through the Internet. Standard protocols like HTTP can be used to access them. Web services are based on the Simple Object Access Protocol (SOAP), which is an application of XML. Web services are given the .asmx extension..

Question: Define Protocols that helps Web Services in Asp Net?
Answer: From my point of view Web Services used three protocols for interacting with the clients.Http-Post,Http-Get,SOAP.

Question: What are VSDISCO files ?
Answer: VSDISCO files are DISCO files that enable dynamic discovery of Web Services. ASP.NET links the VSDISCO to a HTTP handler that scans the host directory and subdirectories for ASMX and DISCO files and returns a dynamically generated DISCO document. A client who requests a VSDISCO file gets back what appears to be a static DISCO document.

Question: What is UDDI ?
Answer: UDDI stands for Universal Description, Discovery, and Integration. It is like an "Yellow Pages" for Web Services. It is maintained by Microsoft, IBM, and Ariba, and is designed to provide detailed information regarding registered Web Services for all vendors. The UDDI can be queried for specific Web Services.

Question: Is it possible to generate the source code for an ASP.NET Web service from a WSDL ?
Answer: The Wsdl.exe tool (.NET Framework SDK) can be used to generate source code for an ASP.NET web service with its WSDL link.
Example: wsdl /server http://api.google.com/GoogleSearch.wsdl.



Question: Can you give an example of when it would be appropriate to use a web service as opposed to a non-serviced .NET component ?
Answer: When to Use Asp Net Web Services:
(i)Communicating through a Firewall When building a distributed application with 100s/1000s of users spread over multiple locations, there is always the problem of communicating between client and server because of firewalls and proxy servers. Exposing your middle tier components as Web Services and invoking the directly from a Windows UI is a very valid option.

(ii)Application Integration When integrating applications written in various languages and running on disparate systems. Or even applications running on the same platform that have been written by separate vendors.

(iii)Business-to-Business Integration This is an enabler for B2B intergtation which allows one to expose vital business processes to authorized supplier and customers. An example would be exposing electronic ordering and invoicing, allowing customers to send you purchase orders and suppliers to send you invoices electronically.

(iv)Software Reuse This takes place at multiple levels. Code Reuse at the Source code level or binary componet-based resuse. The limiting factor here is that you can reuse the code but not the data behind it. Webservice overcome this limitation. A scenario could be when you are building an app that aggregates the functionality of serveral other Applicatons. Each of these functions could be performed by individual apps, but there is value in perhaps combining the the multiple apps to present a unifiend view in a Portal or Intranet.

Question: What are Service Oriented Architectures (SOA) ?
Answer: SOA describes an information technology architecture that enables distributed computing environments with many different types of computing platforms and applications. Web services in asp net are one of the technologies that help make SOAs possible. As a concept, SOA has been around since the 1980s, but many early IT technologies failed to achieve the goal of linking different types of applications and systems. By making early investments with .NET, Microsoft has helped provide the building blocks that today are putting many enterprise customers on the path to successfully implementing SOAs. With SOAs, companies can benefit from the unimpeded flow of information that is the hallmark of connected systems.

Question: What is .NET Passport ?
Answer: .NET Passport is a Web-based service that is designed to make signing in to Web sites fast and easy. Passport enables participating sites to authenticate a user with a single set of sign-in credentials, alleviating the need for users to remember numerous passwords and user names.