Chapter 14 Communicating with Other Applications Outline and Objectives

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Chapter 14 Communicating with Other
ApplicationsOutline and Objectives

• OLE Object Linking and Embedding
• Accessing the Internet With Visual Basic
• Web Page Programming with VBScript

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14.1 OLE

• Is the evolving technology that allows
  programmers to use Visual Basic to glue together
  applications like spreadsheet and word
  processing.
• The three types of OLE are known as automation,
  linking, and embedding.
• With automation, you control an application from
  your program.
• With linking and embedding, you bring an
  application into your program.

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OLE Automation

• An Excel spreadsheet or a Word document can be
  specified as an OLE Automation object.
• The application can be declared as an object with
  the Set statement and CreateObject function.

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OLE Automation

• OLE Automation involves the following four
  steps
• Declare an object variable with a Dim statement
• Create an OLE Automation object with a
  CreateObject function and assign it to the
  variable with a Set statement
• Transfer commands and/or data to the OLE
  Automation object to carry out the desired task
• Close the object and assign the value Nothing to
  the object variable.

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Example 2, pp. 669creates a Word document and
saves the document to a file

• Private Sub cmdCreate_Click()
• Dim objWord As Object
• Set objWord CreateObject("Word.Basic")
• objWord.FileNewDefault
• objWord.Insert "I can resist anything."
• objWord.Wordleft
• objWord.Bold
• objWord.Insert ", except temptation
• objWord.FileSaveAs App.Path "\QUOTE.DOCThe
  word document is created
• objWord.FileClose
• Set objWord Nothing
• End Sub

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The OLE Container Control

• An OLE Container control provides a bridge to
  Windows applications.
• The application can be either linked or embedded
  through the OLE Container control.
• With linking, a link is established to the data
  associated with the application and only a
  snapshot of the data is displayed.
• With embedding, all the applications data are
  actually contained in the OLE Container control
  and no other application has access to the data.

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14.2 What is the Internet?

• Internet stands for inter-net worked
  communication
• The Internet is a collection of thousands of
  networks linked by a common set of technical
  protocols.
• The Internet is a global system of networked
  computers.
• The Internet consists of the following
  components
• The World Wide Web (WWW)
• Usenet newsgroup
• E- mail (SMTP)
• File Transfer Protocol (FTP)
• Telnet

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Internet

• To add the Web Browser Control to Your Visual
  Basic ToolBox
• Invoke Visual Basic
• Press CtrlT to invoke the Components dialog box
• Click the check box next to Microsoft Internet
  Controls.
• Click the OK button
• The Web Browser icon should now appear in your
  toolbox.

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Example of A Simple Web Browser
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Example 1, pp. 678 - creates a simplified web
browser

• Private Sub cmdRetrieve_Click()
• 'Calls up the URL typed in the Text Box
• WebBrowser1.Navigate (txtURL.Text)
• End Sub
• Private Sub Form_Load()
• WebBrowser1.GoHome 'Calls up Internet
  Explorer's home page
• End Sub
• Private Sub Form_Resize()
• 'Resizes the Web Browser control with the Form,
  as long
• 'as the form is not minimized.
• 'Occurs when an object is first displayed
• If Form1.WindowState ltgt 1 Then
• WebBrowser1.Width Form1.ScaleWidth
• WebBrowser1.Height Form1.ScaleHeight - 740
  'Subtract Toolbar height
• End If
• End Sub

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Example continues

• Private Sub WebBrowser1_NavigateComplete(ByVal
  URL As String)
• 'Is activated when the HTML control finishes
• 'retrieving the requested Web page.
• 'Updates Text Boxs URL Display to show current
  URL
• On Error Resume Next 'Eliminates error
  messages
• txtURL.Text WebBrowser1.LocationURL
• End Sub

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Web Browser Control

• Additional properties of the Web Browser control
  are
• LocationURL gives the URL of the current page.
• LocationName gives the title of the current
  page.
• Busy Has the value True if the control is
  downloading a file or navigating to a new
  location.
• Some additional methods of the Web Browser
  control are
• GoForward Undoes the most recent GoBack method.
• GoSearch Goes to the users web searching page.
• Stop Cancels the current operation of the
  control.

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Web Browser Control

• Some additional events of the Web Browser control
  are
• BeforeNavigate Triggered right before the
  control moves to a new location
• ProgressChange Triggered periodically as the
  downloading continues.
• DownloadComplete Triggered when the download is
  complete, halted, or failed.

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Web Page Programming with VBScript

• Web browser displays Web pages created as text
  files, called HTML (HyperText Markup Language)
  documents.
• VBScript is a subset of the VB programming
  language that is used to make Web pages
  interactive.

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HTML

• An example of an HTML document
• ltHTMLgt
• ltHEADgt
• ltTITLEgtIntroduction to Visual Basic lt/TITLEgt
• lt/HEADgt
• ltCENTERgt
• ltA HREF"http//www.eas.asu.edu/csedept/"gt
• ltIMG SRC"../dlogo.gif" border0 ALT"CSE
  Department Home Page"gt
• lt/Agt
• lt/CENTERgt
• ltBODY bgcolor"FFF9E6"gt
• ..
• ..
• lt/BODYgt
• lt/HTMLgt

Every html document starts with this tag
Creates a hyperlink to an image
Ending tag
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HTML

• Tags are used to mark up text with display
  instructions
• The combination of a pair of tags and the text
  enclosed is called an element.

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Placing ActiveX controls in HTML documents

• With Internet Explorer, ActiveX controls, such as
  textboxes, command buttons, and user-built
  controls, can be placed on Web pages.
• The ActiveX control pad makes it easier to place
  text, controls, and programs into HTML document.

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Steps to Create ActiveX Control

• Create a New Project
• From the File menu, select Add Project command,
  click on ActiveX Control (VB uses the same
  metaphor for building ActiveX Controls as
  building applications)
• Draw the Visual Interface for the Control
• Write event driven Code
• Use and Test the Control
• Prepare your Control for Internet Explorer
• To learn more on the ActiveX Control Pad, enter
  the following address
• http//msdn.microsoft.com/vbasic/technical/tutori
  al/activex.aspintro