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Calling scripts within scripts

, 29 Jan 2000 CPOL
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A Component for calling a URL from an ASP script and reading back the output
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  • Overview

    When writing an ASP script, it is sometimes useful to temporarily transfer execution to another script, and then continue the original script with the result of the called script.

    This is what the AspRetrieve component does. You can think of it like calling a procedure.

    The AspRetrieve component acts similar to the new function Server.Execute in IIS 5.0. In addition, you can pass parameters, either by GET or by POST.

    The functionality of the AspRetrieve component in brief:

    • call any URL from within an ASP script
    • pass parameters to the URL either in the URL itself (i.e. by GET) or by POST
    • retrieve the results form the called URL as a string

    Because I only needed limited functionality, only textual results are correctly returned from the called URL. i.e. you can call a HTML page, or an ASP script, but you cannot call a GIF or JPEG image, since the latter two return binary data.

    If you would like to extend the functionality, I would love to have this new version.

    Details

    The AspRetrieve component consists of two parts:

    • A MFC/ATL component that uses the Wininet functions to call an URL
    • Some ASP functions that aid in accessing the MFC component

    In addition I included some examples

    Installation

    • Compile the MFC/ATL part of the component, using Visual C++ (I used the german version of Visual C++ 6, SP3)
    • Copy the component to whatever directory you want it, ensuring the account under which IIS runs (IUSR_XXX) has the correct permissions to access the component
    • Register the compiled component using regsvr32 (which is in your windows' system directory). Just type regsvr32 aspretrieve.dll at the command prompt
    • Copy the ASP function file retrieve.inc to whatever directory you want
    • Include retrieve.inc in your projects and begin using it

    Usage

    When everything is installed correctly, just include the retrieve.inc file in your ASP scripts and call the two functions Retrieve(url) and RetrievePost(url,params). You can either use relative URLs or absolute URLs for calling.

    A practical use of the component is at those places, where you would need a lot of Response.Write statements to produce HTML output. Those functions can now be separated into extra ASP files, feeded with parameters and called via the AspRetrieve component.

    Example

    Imagine you have a function that creates a table by code. 

    Without the AspRetrieve component, you would write something like this to implement the function:

    sub makeTable( byval cols, byval rows )
    	dim c,r
    
    	Response.Write "<table border=""0"" width=""100%"">"
    
    	' create rows.
    	for r=1 to rows
    		Response.Write "<tr>"
    
    		' create cols.
    		for c=1 to cols
    			Response.Write "<td width=""100%""></td>"
    		next
    
    		Response.Write "</tr>"
    	next
    
    	Response.Write "</table>"
    end sub

    You call the function like this:

    <% makeTable 10, 20 %>

    When using the AspRetrieve, you implement the function in a separate ASP script like this:

    <table border="1" width="100%">
    	<%
    	' create rows.
    	dim c,r
    	for r=1 to Request("rows")
    	%>
    
    		<tr>
    
    			<%
    			' create cols.
    			for c=1 to Request("cols")
    			%>
    				<td width="100%"></td>
    			<%
    			next
    			%>
    
    		</tr>
    	<%
    	next
    	%>
    </table>

    You could then write a wrapper to simplify calling:

    sub makeTable( byval cols, byval rows )
    	Response.Write Retrieve( "maketable.asp?cols="&cols&"&rows="&rows )
    end sub

    And finally you would call the wrapper in your code

    <% makeTable 10, 20 %>

    Conclusion

    The advantages of using AspRetrieve are that you can divide a complex application into individual modules. You can create a library of ASP scripts that you can call as needed. 

    In addition by cutting down the number of times you need to use Response.Write, you simplify your code. Having code in separate files, you can even use a graphical layout tool to modify your files, which is impossible if you construct your page with Response.Write.

    Another benefit is that you no longer need to include all files "at compile-time" using the <!--#include--> directive, but can "include" these files dynamically at runtime using the Retrieve function! (a feature that e.g. JSP has by default).

    Please feel free to ask any questions you have by e-mail: keim@zeta-software.de.

    License

    This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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    About the Author

    Uwe Keim
    Chief Technology Officer Zeta Producer Desktop CMS
    Germany Germany
    Uwe does programming since 1989 with experiences in Assembler, C++, MFC and lots of web- and database stuff and now uses ASP.NET and C# extensively, too. He has also teached programming to students at the local university.
     
    In his free time, he does climbing, running and mountain biking. Recently he became a father of a cute boy.
     
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    Comments and Discussions

     
    General"Print & Go" script with Uwe's help PinmemberJuliansongs7-May-04 0:34 
    QuestionHave you guys tried this? PinmemberChristianCalderon15-Feb-04 17:32 
    AnswerRe: Have you guys tried this? PinsitebuilderUwe Keim15-Feb-04 20:49 
    Generalaspretrieve.dll in asp .net Pinmemberhaninaya2-Dec-03 4:38 
    QuestionHow to through proxy? Pinsusstonyjun15-Oct-02 23:30 
    QuestionHow to get AspRetrieve? PinsussAnonymous20-Sep-02 0:48 
    How to get AspRetrieve?
    AnswerRe: How to get AspRetrieve? PinsitebuilderUwe Keim20-Sep-02 0:58 
    GeneralRe: How to get AspRetrieve? PinsussAnonymous20-Sep-02 1:06 
    GeneralHey ,Uwe.I use your component,some error occured. PinsussAnonymous20-Sep-02 1:29 
    GeneralConfirmation of Previous Message PinsussGravity6-Aug-02 20:42 
    GeneralRe: Confirmation of Previous Message PinsitebuilderUwe Keim20-Sep-02 0:59 
    QuestionIs WinInet really suitable for this ?? PinmemberChristian Tratz20-Jun-01 5:10 
    QuestionCan someone send me a compiled dll PinmemberAlan Warchuck8-Mar-01 11:21 
    QuestionNew session? PinmemberGuy25-Jan-01 1:01 
    Questionbug? PinmemberAndre Milton18-Jan-01 21:52 
    AnswerRe: bug? PinmemberUwe Keim18-Jan-01 21:54 
    GeneralRe: bug? PinmemberAndre Milton18-Jan-01 22:02 

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