How To Read and Display Binary Data in ASP

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This article shows how to read and display binary data using Active Server Pages.

Many developers appreciate the ease of using the Scripting.FileSystemObject to open an ASCII file and then display its contents in Microsoft Word or Microsoft Excel from within Internet Explorer. In its current inception, ASP does not directly provide any comparable objects to read files that contain binary data such as an Excel worksheet with macros, an Adobe Acrobat (.pdf) file, a .gif image, or any other files that contain binary data. However, an ASP developer can write a custom business object or component that adds this functionality.


Part I provides the ASP code that receives and then displays the binary file using an appropriate MIME type, and Part II shows how to create the Visual Basic 5.0 (or later) ActiveX DLL component that extends the capability of ASP to read binary data.

Part I: ASP Sample That Opens an Excel Worksheet Containing Macros

   Response.buffer = TRUE
   Response.ContentType = "application/x-msexcel"

   Dim vntStream

   Set oMyObject = Server.CreateObject("MyObject.BinRead")
   vntStream = oMyObject.readBinFile("c:\temp\tempxls.xls")


   Set oMyObject = Nothing


NOTE: For Acrobat files, change the MIME type by using Response.ContentType = "application/pdf". For a .gif image, use Response.ContentType = "image/gif".

Part II: The Visual Basic 5.0 ActiveX DLL (MyObject.BinRead)

To create the component that performs the binary read, perform the following steps:
  1. Create a new ActiveX DLL project in Visual Basic 5.0 or later.
  2. Rename the project MyObject.
  3. Rename the class module BinRead.
  4. Cut and paste the following code into the General Declarations section of the class module:
       Function readBinFile(ByVal bfilename As String) As Variant
              Dim fl As Long
              Dim FileNum As Long
              Dim binbyte() As Byte
              Dim binfilestr As String
              On Error GoTo errHandler
              FileNum = FreeFile
              Open bfilename For Binary Access Read As #FileNum
              fl = FileLen(bfilename)
              ReDim binbyte(fl)
              Get #FileNum, , binbyte
              Close #FileNum
              readBinFile = binbyte
              Exit Function
              Exit Function
          End Function
  5. Save the project.
  6. On the File menu click Make MyObject.dll.
If your Web server is on a separate machine from where you created the component, you need to copy the component onto the Web server and register it using RegSvr32.

To incorporate the file created in Part I into another ASP page that has text or other formatting, use a server side include statement.


Article ID: 193998 - Last Review: March 16, 2005 - Revision: 2.5
  • Microsoft Visual Basic 5.0 Professional Edition
  • Microsoft Visual Basic 6.0 Professional Edition
  • Microsoft Visual Basic 5.0 Enterprise Edition
  • Microsoft Visual Basic Enterprise Edition for Windows 6.0
  • Microsoft Active Server Pages 4.0
kbcode kbfso kbhowto kbscript KB193998

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