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Published: Wednesday, November 01, 2000

Using Microsoft's XMLHTTP Object to Get Data From Other Web Pages

By Richard Lowe

There are several popular commercial COM components that retrieve data from other web sites via HTTP requests, such as AspTear and AspHTTP. There is another lesser know option from Microsoft, however. Microsoft's suite of XML DOM (Document Object Model) components includes the XMLHTTP object. This object was originally designed to provide client-side access to XML documents on remote servers through the HTTP protocol. It exposes a simple API which allows you to send requests (yes, even POSTS) and get the resultant XML, HTML or binary data!

- continued -

(There is one side note at the time of this writing: Microsoft's MSXML 3.0 has just been released. It contains a server-side specific version of the XMLHTTP component for use in web or application servers. Therefore, unless you download v3.0 you are going to have to use the original version, which shouldn't be a problem for most applications.)

Getting Started
If you've been keeping up with versions of Internet Explorer, you probably have some version of MSXML installed. If you need to install it, you can either install the latest version of MDAC or the MSXML component itself. If you don't have it installed, you may get the error: Invalid ProgID when you execute Server.CreateObject("Microsoft.XMLHTTP").

The most basic function of XMLHTTP is simply returning the entire text of a web page, here is the syntax:

  Response.Buffer = True
  Dim objXMLHTTP, xml

  ' Create an xmlhttp object:
  Set xml = Server.CreateObject("Microsoft.XMLHTTP")
  ' Or, for version 3.0 of XMLHTTP, use:
  ' Set xml = Server.CreateObject("MSXML2.ServerXMLHTTP")

  ' Opens the connection to the remote server.
  xml.Open "GET", "http://www.4Guysfromrolla.com/", False
  ' Actually Sends the request and returns the data:

  'Display the HTML both as HTML and as text
  Response.Write "<h1>The HTML text</h1><xmp>"
  Response.Write xml.responseText
  Response.Write "</xmp><p><hr><p><h1>The HTML Output</h1>"

  Response.Write xml.responseText
  Set xml = Nothing
[View the live demo!]

This code will write the entire 4GuysFromRolla.com default page to the browser that requests it. The responseText property contains a the entire text of the page returned as a string.

Getting Binary Data
It's extremely simple to return binary data using the XMLHTTP object, the syntax is exactly the same, but you return the respondsBody property, which is an array of unsigned bytes:

  Response.Buffer = True
  Dim objXMLHTTP, xml
  Set xml = Server.CreateObject("Microsoft.XMLHTTP")
  xml.Open "GET", _
      "http://www.4guysfromrolla.com/webtech/code/mitchell-pres.zip", _

  ' Add a header to give it a file name:
  Response.AddHeader "Content-Disposition", _
  ' Specify the content type to tell the browser what to do:
  Response.ContentType = "application/zip"
  ' Binarywrite the bytes to the browser
  Response.BinaryWrite xml.responseBody

  Set xml = Nothing
[View the live demo!]

We'll continue our investigation of XMLHTTP's capabilities in Part 2 of this article!

  • Read Part 2!

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