MELJUN CORTES VB.net_Understanding Web Service.net

8/8/2019 MELJUN CORTES VB.net_Understanding Web Service.net

http://slidepdf.com/reader/full/meljun-cortes-vbnetunderstanding-web-servicenet 1/14

Visual Basic .NET Programming

What is aWhat is aWhat is aWhat 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 STI

Page 1 of 14

supporting frameworks for the Web

services: Open Internet Protocols

XML Messages and SOAP

Messages defined by Web Services

Description Language (WSDL)




Web ServiceWeb ServiceWeb ServiceWeb Service

Module Module Module Module

used to group the files needed to create a

Web service

contains two files:

.asmx

• includes the WebService directive


Page 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” %>




Adding Public Adding Public Adding Public Adding Public

Subroutines or FunctionsSubroutines or FunctionsSubroutines or FunctionsSubroutines or Functions

Example:

<WebMethod()> Public FunctionAddAdminUsr(ByVal strName As

String) As String

‘ Functionality to add a user and


Page 3 of 14

re urn new

…

Return strNewIdEnd Function

<WebMethod()> Public Sub

DeleteAdminUsr(ByVal strId As

String)

‘ Functionality to delete a user based

on ID

…

End Sub




DynamicDynamicDynamicDynamic

Discovery Document Discovery Document Discovery Document Discovery Document

contains information about the Web

service

used to locate and discover Web services

automaticall created b ASP.NET


Page 4 of 14

return the details of all Web Services

uses the .vsdisco file extension

used to exclude particular folders from

the dynamic discovery process




HTML Description PageHTML Description PageHTML Description PageHTML Description Page

and WSDL Document and WSDL Document and WSDL Document and WSDL Document

The HTML description page

describes Web services methods and

arguments

displayed when Web service URL is enteredwithout specifying a particular method

name

contains simple test utility methods


Page 5 of 14

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




HTML Description PageHTML Description PageHTML Description PageHTML Description Page

and WSDL Document and WSDL Document and WSDL Document and 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


Page 6 of 14

Example:

http://localhost:3163/MyService.asmx?WSDL




Invoking a Web ServiceInvoking a Web ServiceInvoking a Web ServiceInvoking a Web Service from a Browser from a Browser from a Browser from a Browser

and a Client and a Client and a Client and 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


Page 7 of 14

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>






HTTP GET method

used to send the form data to the Web

server

most commonly used for testing purposes

SOAP protocol

used for real a lication-to-a lication


Page 8 of 14

communication

difference between the HTTP-GET andSOAP

the way of sending data to the Web server






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


Page 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




Demo: Creating aDemo: Creating aDemo: Creating aDemo: Creating a


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


Page 10 of 14

e e e e asmx e

delete the vb file

right-click on the project name and clickAdd 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






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

”


Page 11 of 14

)> Public Class WebServiceDemo

delete the code:

<WebMethod()> _

Public Function HelloWorld()

As String

Return "Hello World"

End Function






To define the Web Service methods:

add WebMethod attribute and Web service

method

<WebMethod(Description:="Retrieves

welcome message.")> _

Public Function GetMessage()


Page 12 of 14

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







Page 13 of 14

click the Service Description hyperlink






click the Back button

click the hyperlink of the method of the

Web Service


Page 14 of 14

click the Invoke button

Documents

MELJUN CORTES VB.net_Understanding Web Service.net