📤 ASP – Response / Request – Handle Server Communication in Classic ASP

🧲 Introduction – What Are Response and Request in Classic ASP?

In Classic ASP, the Request and Response objects are core components that allow your server-side scripts to interact with browser clients.

• Request is used to receive data from a client (such as form input, cookies, or query strings).
• Response is used to send data back to the client (such as HTML content, headers, cookies, or redirects).

🎯 In this guide, you’ll learn:

• How to use the Request object to retrieve user input
• How to use the Response object to send content and headers
• Real-world usage with forms, cookies, and redirects
• Output examples and best practices

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📥 The Request Object – Receiving Client Data

📌 Common Request Collections

Collection	Description
Request.Form	Data from HTML forms using POST
Request.QueryString	Data from the URL (GET method)
Request.Cookies	Cookies sent by the client
Request.ServerVariables	Info about the server and environment
Request.Headers	HTTP headers sent from client (IIS 5+)

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✅ Example: Read Form Input

HTML form (POST):

<form method="post" action="submit.asp">
  <input type="text" name="username">
  <input type="submit" value="Submit">
</form>

submit.asp (ASP):

<%
Dim user
user = Request.Form("username")
Response.Write "Hello, " & user
%>

🧪 Output:
Hello, Alex (if Alex was entered)

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🔍 Example: Read Query String Parameters

<%
Dim page
page = Request.QueryString("id")
Response.Write "Page ID: " & page
%>

🧪 URL: example.asp?id=5
🧪 Output: Page ID: 5

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🍪 Example: Access Client Cookies

<%
Dim theme
theme = Request.Cookies("Theme")
Response.Write "Your theme: " & theme
%>

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📤 The Response Object – Sending Output to Browser

✅ Basic Output with Response.Write

<%
Response.Write "Welcome to my site!"
%>

🧪 Output:
Welcome to my site!

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🔄 Redirect to Another Page

<%
Response.Redirect "home.asp"
%>

📌 Immediately redirects the user to home.asp.

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🍪 Set a Cookie

<%
Response.Cookies("Theme") = "Dark"
Response.Cookies("Theme").Expires = Date + 30
%>

🧪 Sets a cookie named Theme valid for 30 days.

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🧾 Set Content Type (e.g., JSON or CSV)

<%
Response.ContentType = "application/json"
Response.Write "{""status"":""success""}"
%>

🧪 Used in API or AJAX responses.

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⚠️ Common Mistakes to Avoid

Mistake	Correction
Using Request("field") without checking	Use IsEmpty() or Len() to validate input
Writing to Response after Redirect	Always Exit after Response.Redirect()
Not escaping user input	Always sanitize inputs to prevent XSS or SQLi

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🧘 Bonus: Loop Through All Form Values

<%
Dim field
For Each field In Request.Form
    Response.Write field & ": " & Request.Form(field) & "<br>"
Next
%>

🧪 Output: Displays all submitted form fields and their values.

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📘 Best Practices for Request/Response

✅ Do:

• Use Request.Form("field") for POST data
• Always validate and sanitize input values
• Use Response.Write to debug server logic
• Exit immediately after Response.Redirect

❌ Avoid:

• Mixing GET and POST unless intentional
• Trusting Request data directly in queries
• Forgetting to set ContentType for APIs

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📌 Summary – Recap & Next Steps

The Request and Response objects are the heartbeat of Classic ASP communication. Together, they allow your ASP pages to receive user input, send dynamic content, and manage browser interaction smoothly.

🔍 Key Takeaways:

• Use Request.Form and Request.QueryString to capture input
• Use Response.Write, Redirect, and Cookies to control output
• Always validate and sanitize data from Request

⚙️ Real-world Use Cases:

• Handling form submissions
• Redirecting users after login
• Setting language/theme preferences using cookies

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❓ FAQs – Classic ASP Request / Response

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❓ What’s the difference between Request.Form and Request.QueryString?
✅ Request.Form is for POST data, while Request.QueryString reads from the URL (GET data).

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❓ How do I output a variable in Classic ASP?
✅ Use Response.Write, or the shorthand <%= variable %>.

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❓ Can I write to the response after a redirect?
❌ No. Use Response.Redirect("url") followed by Response.End or Exit.

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