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How do I access the built-in ASP objects from VB?

by Adrian Forbes, MVP
Skill rating level 11.

When using IIS3 the only way to get a handle on the built-in ASP objects was via the ScriptingContext. When you use Server.CreateObject, ASP would call the OnStartPage method of your object and pass in a ScriptingContext object. Using that object you could then get a reference to the built-in ASP objects.

Private objScript As ScriptingContext
 
Sub OnStartPage(obj As ScriptingContext)
    Set objScript = obj
End Sub
 
Sub DoSomething()
Dim objResponse As ASPTypeLibrary.Response

    Set objResponse = objScript.Response
    objResponse.Write "<p>Hello World</p>"
End Sub

IIS4 and IIS5 provide this same functionality for backward compatibility but you shouldn't use it. Instead you should get a handle on the built-in objects using the object's ObjectContext. Objects created in ASP are given their own context and you can choose to hook into that context if you want to. In your VB Object Add a reference to COM+ Services Type Library if you are using Win2k , or to MTS if you are using Windows NT, and a reference to Microsoft Active Server Pages Object Library. Although we are adding a reference to MTS/COM+ you don't actually need to register the DLL with MTS, or register it as a configured component under Win2k. The reason being is that, under the covers, your scripts are running in the MTS environment anyway, we're just choosing to utilise it. If you do want to add your component to MTS/COM+ then that is fine too. The thing to note is that you can add the object to MTS or you can leave it as a normal DLL, using this technique does not restrict your deployment choices.

In our VB code the built-in ASP objects are held in the Items collection of the ObjectContext. Getting a handle on them is a simple matter of;

Dim objResponse As ASPTypeLibrary.Response
    
Set objResponse = GetObjectContext.Item("Response")

We can now use objResponse just as we would the Response object in ASP. Below is a small demo

ContextTest1.asp
<%@ Language=VBScript %>
<HTML>
<BODY>

<%
if len(trim(Session("FullName"))) > 0 then
	Response.Write "<p>I remember your name as " & Session("FullName") & "</p>"
end if
%>

<FORM action="ContextTest2.asp" method=POST>
Surname: <input type="text" name="txtSurname"><br>
Forename: <input type="text" name="txtForename"><br>
<input type="submit" value="Submit">
</FORM>

ContextTest2.asp
<%@ Language=VBScript %>
<%
set obj = Server.CreateObject("ASPObject.ASPClass")
obj.DoStuff
set obj = nothing
%>

VB Code

Create an ActiveX DLL project called ASPObject and add a class called ASPClass. Add a reference to MTS (if using Win NT) or COM+ Services Type Library (if using Win2k) and a reference to ASP (Microsoft Active Server Pages Object Library). Inside ASPClass put the following code.

Option Explicit

Public Sub DoStuff()
Dim objResponse As ASPTypeLibrary.Response
Dim objRequest As ASPTypeLibrary.Request
Dim objSession As ASPTypeLibrary.Session
Dim sSurname As String
Dim sForename As String
Dim sFullName As String
    
    Set objResponse = GetObjectContext.Item("Response")
    Set objRequest = GetObjectContext.Item("Request")
    Set objSession = GetObjectContext.Item("Session")
    
    objResponse.Write "<HTML>" & vbCrLf

    objResponse.Write "<HEAD>" & vbCrLf
    objResponse.Write "</HEAD>" & vbCrLf
    objResponse.Write "<BODY>" & vbCrLf

    sSurname = Trim(objRequest("txtSurname"))
    sForename = Trim(objRequest("txtForename"))

    If Len(sSurname) < 2 Then
        sSurname = UCase(sSurname)
    Else
        sSurname = UCase(Left(sSurname, 1)) & Mid(sSurname, 2)
    End If
    
    If Len(sForename) < 2 Then
        sForename = UCase(sForename)
    Else
        sForename = UCase(Left(sForename, 1)) & Mid(sForename, 2)
    End If
    
    sFullName = sForename & " " & sSurname
    objSession("FullName") = sFullName
    objResponse.Write "<p>Hello " & sFullName & "</p>" & vbCrLf
    
    If Len(Trim(objRequest.ServerVariables("HTTP_REFERER"))) > 0 Then
        objResponse.Write "<p><a href=""" & objRequest.ServerVariables("HTTP_REFERER") & """>Back</a>" & vbCrLf
    End If
    
    objResponse.Write "</BODY>" & vbCrLf
    objResponse.Write "</HTML>"

    Set objResponse = Nothing
    Set objRequest = Nothing
    Set objSession = Nothing

End Sub

 

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