meljun cortes vb.net understanding web service.net
TRANSCRIPT
Visual Basic .NET Programming
What is a What is a What is a What is a Web Service?Web Service?Web Service?Web Service?
� allows access to components by means of
Internet and HTTP
� a class that is stored on one computer
that can be accessed on another computer
over the network
Understanding Web Service * Property of STIPage 1 of 14
� supporting frameworks for the Web
services:
� Open Internet Protocols
� XML Messages and SOAP
� Messages defined by Web Services
Description Language (WSDL)
Visual Basic .NET Programming
Web Service Web Service Web Service Web Service ModuleModuleModuleModule
� used to group the files needed to create a
Web service
� contains two files:
� .asmx
• includes the WebService directive
.asmx.vb file
Understanding Web Service * Property of STIPage 2 of 14
� .asmx.vb file
• contains the code that executes when a
Web Service method is invoked
<%@ WebService Language=”vb”
CodeBehind=”AdminUsr.asmx.vb”
Class=”WebApp.AdminUsr” %>
Visual Basic .NET Programming
Adding Public Adding Public Adding Public Adding Public Subroutines or FunctionsSubroutines or FunctionsSubroutines or FunctionsSubroutines or Functions
� Example:
<WebMethod()> Public Function
AddAdminUsr(ByVal strName As
String) As String
‘ Functionality to add a user and
return new ID
Understanding Web Service * Property of STIPage 3 of 14
return new ID
…
Return strNewId
End Function
<WebMethod()> Public Sub
DeleteAdminUsr(ByVal strId As
String)
‘ Functionality to delete a user based
on ID
…
End Sub
Visual Basic .NET Programming
Dynamic Dynamic Dynamic Dynamic Discovery DocumentDiscovery DocumentDiscovery DocumentDiscovery Document
� contains information about the Web
service
� used to locate and discover Web services
� automatically created by ASP.NET
Understanding Web Service * Property of STIPage 4 of 14
� automatically created by ASP.NET
� return the details of all Web Services
� uses the .vsdisco file extension
� used to exclude particular folders from
the dynamic discovery process
Visual Basic .NET Programming
HTML Description Page HTML Description Page HTML Description Page HTML Description Page and WSDL Documentand WSDL Documentand WSDL Documentand WSDL Document
� The HTML description page
� describes Web services methods and
arguments
� displayed when Web service URL is entered
without specifying a particular method
name
� contains simple test utility methods
� provides test facilities for each methods of
Understanding Web Service * Property of STIPage 5 of 14
� provides test facilities for each methods of
the Web service
� allows you to provide parameter through
an input field
� follows the format:
http://webservername:port/webservi
ce.asmx.
� Example:
http://localhost:3163/MyService.as
mx
Visual Basic .NET Programming
HTML Description Page HTML Description Page HTML Description Page HTML Description Page and WSDL Documentand WSDL Documentand WSDL Documentand WSDL Document
� Web Services Description Language (WSDL)
� describes methods, arguments and
responses of a Web service
� created automatically by adding the ?WSDL
switch to the Web service URL
� Example:
Understanding Web Service * Property of STIPage 6 of 14
� Example:
http://localhost:3163/MyService.as
mx?WSDL
Visual Basic .NET Programming
Invoking a Web Service Invoking a Web Service Invoking a Web Service Invoking a Web Service from a Browser from a Browser from a Browser from a Browser
and a Clientand a Clientand a Clientand a Client
� To invoke a Web Service from a browser:
� enter the URL of the service, specify the
method name to run as well as parameter
values
� Syntax:
http://webservername/vdir/webservi
Understanding Web Service * Property of STIPage 7 of 14
http://webservername/vdir/webservi
cename.asmx/MethodName?parameter
=value
� Examples:
http://www.myserver.com/User/Admin
Usr.asmx/AddAdminUsr?strName=Man
ny
<?xml version=”1.0” ?>
<string
xmlns=http://tempuri.org/>43-
124-21</string>
Visual Basic .NET Programming
Invoking a Web Service Invoking a Web Service Invoking a Web Service Invoking a Web Service from a Browser from a Browser from a Browser from a Browser
and a Clientand a Clientand a Clientand a Client
� HTTP GET method
� used to send the form data to the Web
server
� most commonly used for testing purposes
� SOAP protocol
� used for real application-to-application
Understanding Web Service * Property of STIPage 8 of 14
� used for real application-to-application
communication
� difference between the HTTP-GET and
SOAP
� the way of sending data to the Web server
Visual Basic .NET Programming
Invoking a Web Service Invoking a Web Service Invoking a Web Service Invoking a Web Service from a Browser from a Browser from a Browser from a Browser
and a Clientand a Clientand a Clientand a Client
� To invoke a Web service from a client:
� add a Web reference to the Web Service
� enter the URL for the .asmx file
� select the required references
� create the client code for accessing a
component
Understanding Web Service * Property of STIPage 9 of 14
� Example:
Private Sub btnSubmit_Click(ByVal
sender As System.Object, _
ByVal e As System.EventArgs)
Handles btnSubmit.Click
’Services is the given namespace
Dim usr As New Services.user( )
MessageBox.Show(usr.AddUser(txtNam
e.Text))
End Sub
Visual Basic .NET Programming
Demo: Creating a Demo: Creating a Demo: Creating a Demo: Creating a Web ServiceWeb ServiceWeb ServiceWeb Service
� open Visual Studio 2005
� File > New Web Site
� select ASP.NET Web Service
� set Location to File System
� set Language to Visual Basic then click
OK
� delete the asmx file
Understanding Web Service * Property of STIPage 10 of 14
� delete the asmx file
� delete the vb file
� right-click on the project name and click
Add New Item
� select Web Service in the Templates list
then set the Web service and click Add
� right-click on the App_Code and click
Add New Item
� select Class from the Installed Templates
list
� set the class name then click Add
Visual Basic .NET Programming
Demo: Creating a Demo: Creating a Demo: Creating a Demo: Creating a Web ServiceWeb ServiceWeb ServiceWeb Service
� open the Code Editor for the .asmx file,
locate the Public Class definition then
modify the WebService attribute
<WebService(Namespace:=”http://tem
puri.org/”, _
Description:=” Web service demo
information.”
Understanding Web Service * Property of STIPage 11 of 14
information.”
)> Public Class WebServiceDemo
� delete the code:
<WebMethod()> _
Public Function HelloWorld()
As String
Return "Hello World"
End Function
Visual Basic .NET Programming
Demo: Creating a Demo: Creating a Demo: Creating a Demo: Creating a Web ServiceWeb ServiceWeb ServiceWeb Service
� To define the Web Service methods:
� add WebMethod attribute and Web service
method
<WebMethod(Description:="Retrieves
welcome message.")> _
Public Function GetMessage()
As String
Understanding Web Service * Property of STIPage 12 of 14
As String
GetMessage = "Learning Web
services is fun!"
End Function
� To test the Web Service:
� right-click on the project name and select
Build Web Site
� right-click the .asmx file, and then click
View in Browser
Visual Basic .NET Programming
Demo: Creating a Demo: Creating a Demo: Creating a Demo: Creating a Web ServiceWeb ServiceWeb ServiceWeb Service
Understanding Web Service * Property of STIPage 13 of 14
� click the Service Description hyperlink
Visual Basic .NET Programming
Demo: Creating a Demo: Creating a Demo: Creating a Demo: Creating a Web ServiceWeb ServiceWeb ServiceWeb Service
� click the Back button
� click the hyperlink of the method of the
Web Service
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� click the Invoke button