Introduction to VB.Net Internet Tools

1. Introduction to VB.Net Internet Tools

2. Web Server • Default directory • C:\InetPub\wwwroot • Computer lab: Zip drive • dchao • Default home page • Default.aspx, default.asp, default.htm

3. Web Project • File/New/ ASP.Net Application • Website folder • Web form: • Webform.aspx • Design view and HTML view • WebForm.Aspx.VB • CodeBehind

4. Web Data Form • Web Data Form Wizard: • Project/Add Web Form/Data Form Wizard

5. 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()

6. 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.

7. ASP.NET Object Model Client Server Request Object Server Object Response Object Application Object Session Object

8. 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.

9. 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

10. 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”>

11. 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

12. 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

13. 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

14. Imports System.IO Imports System.Net Imports System.Text Private 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

15. Change Downloaded Page • For example, use string’s Replace method to change page content. • webData = webData.Replace("Chao", "You") • Search/Replace with Regular Expression

16. 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.

17. 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.

18. 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

19. WebClient/DownloadFile .Save the dowloaded data directly in a file: Dim wc As New WebClient() wc.DownloadFile(txtURL.Text, "c:\testDownLoad.txt")

20. 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

21. 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.

22. 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)

23. 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.

24. 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

25. Creating a Web Service Using VS • New Project/ASP.Net Web Service

26. 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.

27. 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

28. Universal Description, Discovery, and Integration (UDDI) • A directory service for web services. • http://uddi.org

29. 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.

30. 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

31. Using MailMessage Class to Set Email Properties • Email properties: • Attachments • Bcc • Body • BodyFormat • Text or Html • Cc • From • Headers • Subject • To

32. 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