(B) What is a WebService ?
Web Services are business logic components which provide functionality via the Internet
using standard protocols such as HTTP.
Web Services uses simple Object Access Protocol (SOAP) in order to expose the business
functionality.SOAP defines a standardized format in XML which can be exchanged
between two entities over standard protocols such as HTTP.SOAP is platform independent
so the consumer of a Web Service is therefore completely shielded from any
implementation details about the platform exposing the Web Service.For the consumer it
is simply a black box of send and receive XML over HTTP.So any webservice hosted on
windows can also be consumed by UNIX and LINUX platform.
(B) What is UDDI ?
Full form of UDDI is Universal Description,Discovery and Integration.It is a directory
that can be used to publish and discover public Web Services.If you want to see more
details you can visit the http://www.UDDI.org .
(B) What is DISCO ?
Abbreviation of DISCO is Discovery.It is basically used to club or group common services
together on a server and provide links to the schema documents of the services it describes
may require.
(B) What is WSDL?
Web Service Description Language (WSDL)is a W3C specification which defines XML
grammar for describing Web Services.XML grammar describes details such as:-
√ Where we can find the Web Service (its URI)
√ What methods and properties that service supports
√ Data type support.
√ Supported protocols
In short its a bible of what the webservice can do.Clients can consume this WSDL and
build proxy objects that clients use to communicate with the Web Services. Full WSDL
specification is available at http://www.w3.org/TR/wsdl.
(A) What the different phase/steps of acquiring a proxy object in
Webservice ?
The following are the different steps needed to get a proxy object of a webservice at the
client side :-
√ Client communicates to UDI node for WebService either through browser or
UDDI's public web service.
√ UDII responds with a list of webservice.
√ Every service listed by webservice has a URI pointing to DISCO or WSDL
document.
√ After parsing the DISCO document, we follow the URI for the WSDL document
related to the webservice which we need.
√ Client then parses the WSDL document and builds a proxy object which can
communicate with Webservice.
(B) What is file extension of Webservices ?
.ASMX is extension for Webservices.
(B)Which attribute is used in order that the method can be used as
WebService ?
WebMethod attribute has to be specified in order that the method and property can be
treated as WebService.
(A) Do webservice have state ?
Twist :- How can we maintain State in Webservices ?
Webservices as such do not have any mechanism by which they can maintain
state.Webservices can access ASP.NET intrinsic objects like Session, application etc. if
they inherit from “WebService” base class.
<%@ Webservice class="TestWebServiceClass" %>
Imports System.Web.Services
Public class TestWebServiceClass
Inherits WebService
<WebMethod> Public Sub SetSession(value As String)
session("Val") = Value
End Sub
End class
Above is a sample code which sets as session object calles as “val”. TestWebserviceClass
is inheriting from WebService to access the session and application objects
