Introduction to VB.Net Internet Tools

Web Server

• Default directory– C:\InetPub\wwwroot– Computer lab: Zip drive

• dchao

• Default home page– Default.aspx, default.asp, default.htm

Web Project

• File/New/ ASP.Net Application

• Website folder

• Web form:– Webform.aspx

• Design view and HTML view

– WebForm.Aspx.VB• CodeBehind

Web Data Form

• Web Data Form Wizard:– Project/Add Web Form/Data Form Wizard

Bind the DataReader to a DataGrid

Dim strConn As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source = c:\salesDB.mdb" Dim objConn As New OleDbConnection(strConn) Dim strSQL As String = "select * from customer;" Dim objComm As New OleDbCommand(strSQL, objConn) Dim Results As String objConn.Open() Dim objDataReader As OleDbDataReader objDataReader = objComm.ExecuteReader() DataGrid1.DataSource = objDataReader DataGrid1.DataBind()

Note: DataGrid1.DataBind()

ASP.NET

• ASP.NET is a server-side technology for creating dynamic web pages.

• ASP.NET allows you to use a selection of full programming languages. The default language is VB .NET.

• ASP.NET files have a .aspx extension.

ASP.NET Object Model

Client Server

Request Object

Response Object

Server Object

SessionObject

Application

Object

ASP.NET Request Object• When a page is requested, much

information is passed along with the request, such as the URL, queryString, and data from a form. The request object allows you to get the information passed along with the request.

• It is created from the System.Web.HttpRequest class.

FORM Tag

• Form attribute:– Action: Specify the URL of a program on a server or an

email address to which a form’s data will be submitted.

– Method: • Get: the form’s data is appended to the URL specified by the

Action attribute as a QueryString.

• Post: A prefered method for database processing. Form’s data is sent separately from the URL.

– Name: Form’s name

QueryString

• A QueryString is a set of name=value pairs appended to a target URL.

• It can be used to pass information from one webpage to another.

• Example: • <A Href=“

http://my.com/Target.htm?CustID=C1&Cname=Chao”>

Request Object Collections

• QueryString– http://my.com/Target.htm?CustID=C1&CustName=Chao

– cid = Request.queryString(“CustID”)

– cName=Request.queryString(“CustName”)

• Form– A form with two text boxes:CustID, CustName– cid = Request.Form(“CustID”)

– cName=Request.Form(“CustName”)

• Cookies

ASP.NET Response Object

• This object allows you to send information back to client.

• It is created from the System.Web.HttpResponse class.

• Properties:– Cookies (a collection)

• Methods:– Response.Write – Response.Redirect (“URL”)

• Demo: testReqForm.htm, testReqForm.aspx

Downloading Internet Resources

• Download the HTML of a web page and display it in a text box.– System.URI

• A class for expressing a Uniform Resource Identifier.

– System.Net.WebRequest• Makes a request to a Uniform Resource Identifier.

– WebResponse• Provides a response from a Uniform Resource

Identifier.

• Demo: MyBrowser/GetWebPage

Imports System.IO

Imports System.Net

Imports System.TextPrivate Sub BtnGo_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtnGo.Click

Dim URI As New Uri(txtURL.Text)

Dim request As WebRequest = WebRequest.Create(URI)

Dim response As WebResponse = request.GetResponse

Dim stream As Stream = response.GetResponseStream

Dim readStream As New StreamReader(stream)

Dim webData As String = readStream.ReadToEnd

stream.Close()

readStream.Close()

txtData.Text = webData

End sub

Change Downloaded Page

• For example, use string’s Replace method to change page content.– webData = webData.Replace("Chao", "You")

• Search/Replace with Regular Expression

Using the WebClient Class

• This class wraps the Request and Response classes.

• Methods:– DownloadData: Returns a byte array from an

Internet address.– DownloadFile: Save a downloaded file.– OpenRead: Returns a stream from an Internet

address.

UTFEncoding Class

• This class encodes Unicode characters using UCS Transformation Format, 8-bit form (UTF-8). This encoding supports all Unicode character

• Method: GetString– Decodes the specified byte array into a string.

WebClient/Download

Dim wc As New WebClient()

Dim utf8 As New UTF8Encoding()

Dim webData As String

webData = utf8.GetString(wc.DownloadData(txtURL.Text))

txtData.Text = webData

WebClient/DownloadFile

.Save the dowloaded data directly in a file:

Dim wc As New WebClient()

wc.DownloadFile(txtURL.Text, "c:\testDownLoad.txt")

WebClient/OpenRead

Dim wc As New WebClient()

Dim stream As Stream

stream = wc.OpenRead(txtURL.Text)

Dim readStream As New StreamReader(stream)

Dim webData As String = readStream.ReadToEnd

txtData.Text = webData

Hosting Internet Explorer in Windows Forms

• Internet Explorer COM control– Right click Tool Box Windows Form tab and

select Add/Remove Items ….– Select COM Component tab, and Scroll down

to select Microsoft Web Browser.

Internet Explorer COM control• Events

– DownLoadComplete, DownLoadBegin

• Methods:– Navigate

• Dim HomeURL As String = "http://dchaolaptop"• Private Sub MyBrowser_Load(ByVal sender As System.Object, ByVal e

As System.EventArgs) Handles MyBase.Load

• IE.Navigate(HomeURL)• End Sub

– Note: Navigate can take local file path as input to open a local page.

– Goback, GoForward– Stop– Refresh2– GoHome, GoSearch --- (Go to Microsoft home page and

search engine)

Web Service

• XML Web Service

• Web services are classes that are stored on the web which can instantiate and use in both Windows and Web applications.

A Web Service ExampleASPET/TestWebService.ASMX

<%@ WebService Class="CustomerInfo" %>

imports System.Web.Services

imports System

imports System.Data

imports System.Data.Oledb

Public Class CustomerInfo

<webMethod()> public Function GetCname(ByVal CID as String) as String

dim strConn as string ="Provider=Microsoft.Jet.OLEDB.4.0;Data Source = c:\sales2k.mdb"

dim objConn as new OledbConnection(strConn)

dim strSQL as string = "select * from customer where CID = '" & CID & "';"

dim objComm as new OledbCommand(strSQL,objConn)

dim Results as string

objConn.open()

dim objDataReader as oledbDataReader

objDataReader=objComm.executeReader()

objDataReader.read()

return objDataReader("Cname")

end function

Creating a Web Service Using VS

• New Project/ASP.Net Web Service

Web Service Description Language (WSDL)

• A WSDL file is an XML document containing a complete description of the web service. It shows a web service’s name, methods, and parameter types.

• Help page: After entering web service’s URL, a help page is displayed. You can click the Service Description link to see the WSDL file.

Consuming Web Services from a Windows Application

• Add a web reference to the web service.

• Declare a web service class variable.– Dim myWebService As New dchaolaptop.CustomerInfo()

• Demo: UseWebService

Universal Description, Discovery, and Integration (UDDI)

• A directory service for web services.– http://uddi.org

Simple Mail Transport Protocol (SMTP)

• Email messages are text files.• InetPub\MailRoot

– PickUp directory: • SMTP monitors this directory and sends any messages found

in this directory.

– Drop:• Incoming messages received by SMTP are written to this

directory.

– BadMail:• If an email cannot be delivered or returned to the sender it is

moved to this directory.

ASP.Net Email Classes

• SmtpMail class– System.Web.Mail– System.Web.Mail.MailMessage

• Methods:– Send(From, To, Subject, messageText)

• SmtpMail.Send(TextBox1.Text, TextBox2.Text, TextBox3.Text, TextBox4.Text)

– Send(System.Web.Mail.MailMessage)• Demo:

– SendMail.aspx– Import system.web.mail

Using MailMessage Class to Set Email Properties

• Email properties:– Attachments– Bcc– Body– BodyFormat

• Text or Html

– Cc– From– Headers– Subject– To

Using MailMessage with Attachment

Dim objMsg As New MailMessage objMsg.From = TextBox1.Text objMsg.To = TextBox2.Text objMsg.Subject = TextBox3.Text objMsg.Body = TextBox4.Text Dim attachment As MailAttachment = New MailAttachment("c:\paradise.jpg") objMsg.Attachments.Add(attachment) Try SmtpMail.Send(objMsg) Catch ex As SystemException MessageBox.Show(ex.Message) End Try