Building websites with Active Server Pages

#asp #web-development

Written by Anders Marzi Tornblad

In today's fast-paced digital world, the static, one-way communication style of the early web has given way to a new demand for interactive, dynamic websites. Users now expect to be able to interact with web pages, input data, and see the result of their actions instantly. They want content that's tailored to their interests, location, and preferences. That's where Active Server Pages (ASP) come in.

ASP, a server-side scripting environment developed by Microsoft, allows us to build web pages that can interact with databases, process user input, and deliver custom content on the fly. It's the secret sauce that turns a static HTML site into a dynamic web application.

The Basics of ASP

ASP, short for Active Server Pages, operates as a server-side scripting environment developed by Microsoft. Its primary purpose? Building web pages that are not static, but dynamic and interactive. These pages can interface with databases, process user input, and provide users with content tailored to their unique needs and interests. In this sense, the functionality of ASP is a step up from static HTML pages, bringing them into the realm of full-fledged web applications.

A pivotal characteristic of ASP is that it uses scripts that run on the web server rather than within the user's browser, as is the case with client-side scripts such as JavaScript. The advantage here is that these scripts can generate HTML content dynamically, adjusting the output depending on factors such as user input, the time of day, or the results of a database query. Each user's experience can thus be unique, depending on their interactions and data.

ASP scripts are typically written in Microsoft's own language, Visual Basic Scripting Edition (VBScript), a scripting language that shares its roots with Visual Basic. For those who are already acquainted with Visual Basic due to building applications for Windows, this can make for a smoother transition to web development. VBScript is straightforward and intuitive, featuring a syntax that is easy to read and write. This makes it a good choice for those starting in server-side scripting. If you're not a fan of VBScript, don't worry. ASP also supports other languages, such as JScript, which is Microsoft's implementation of JavaScript on the server side.

The real power of ASP becomes evident in its seamless integration with other Microsoft technologies. A prime example is the Component Object Model (COM), a Microsoft technology that allows software components to communicate with one another. This technology is the backbone of many Microsoft technologies and services, and it enables developers to reuse components across different applications, fostering code efficiency and consistency.

Another essential technology closely related to ASP is ActiveX Data Objects (ADO), a set of data access components that provide a uniform way to access data from various sources. ADO's power lies in its ability to interface with databases. With ADO, ASP can perform operations such as querying a database and updating records, which are fundamental tasks for creating interactive, data-driven websites.

The ASP environment offers built-in objects that simplify the process of web development. For example, Request and Response objects handle the exchange of data between the client and server, enabling the retrieval of form data or cookies (via the Request object), or the sending of HTML content or redirects to the client (via the Response object). Session and Application objects allow the storage of information that can be accessed across multiple pages or by all users of an application, respectively. This capability is crucial for maintaining state in what is inherently a stateless environment - the HTTP protocol. Finally, Server and Error objects provide various utility functions and a way to handle and report errors, which is a crucial part of any robust application.

In summary, ASP offers a powerful server-side scripting environment that, coupled with VBScript, COM, and ADO, enables the creation of dynamic, interactive, and data-driven websites. With these tools, you can transform static HTML pages into engaging, user-centric web applications.

Building a Simple ASP Website

Now let's roll up our sleeves and build a small part of an ASP-driven website. For the sake of simplicity, we'll create a user registration form that interacts with a database.

First, we'll need an HTML form:

<form method="post" action="register.asp">
      <td><input type="text" name="username"></td>
      <td><input type="password" name="password"></td>
    <!-- More form fields as needed -->
      <td colspan="2">
        <input type="submit" value="Register">

The "register.asp" in the action attribute is the ASP script that will process this form. Here's what it might look like:

  dim conn, rs, name, email
  set conn = Server.CreateObject("ADODB.Connection")
  conn.Open "DSN=your_dsn;UID=your_uid;PWD=your_pwd;"

  username = Request.Form("username")
  password = Request.Form("password")

  insert = "INSERT INTO users (username, password) "
  values = "VALUES ('" & username & "', '" & password & "')"
  sql = insert & values


  Response.Redirect "success.html"
<p>Thank you for registering!</p>

This script begins with creating an ADO Connection object and opens a connection to the database. Then it retrieves the data submitted by the user with the Request.Form method. A SQL query string is created to insert the new user's details into the "Users" table. The Execute method of the Connection object runs the SQL query, then we close the connection and present the user with a message.

The Importance of Server-Side Scripting

As we move forward in the digital age, the importance of server-side scripting becomes increasingly apparent. With web experiences evolving from static pages to dynamic, interactive applications, mastering server-side scripting has become an essential skill for today's web developers. It's a game-changer, and here's why.

The problem server-side scripting solves is two-fold. First, it allows developers to generate dynamic content that can change based on a myriad of factors, such as user input, the time of day, or the results of a database query. This capability opens the doors to user-centric experiences tailored to an individual's needs or preferences. For example, consider an online shopping website that suggests products based on a user's past purchases or browsing history. This level of personalization wouldn't be possible without server-side scripting.

Second, server-side scripting enables the maintenance of state across multiple pages in what is inherently a stateless protocol - HTTP. The HTTP protocol, which underpins data communication on the World Wide Web, doesn't retain information from one request to another. This stateless nature can pose challenges when trying to create seamless experiences for users, such as keeping a user logged in as they navigate through a website. Server-side scripting addresses this issue by using techniques such as sessions or cookies, enabling state information like user credentials or shopping cart items to be preserved across multiple user requests.

When considering server-side scripting, it's helpful to contrast it with its client-side counterpart. Client-side scripting, such as JavaScript, operates in the user's browser and is excellent for handling user interactivity, manipulating page elements, and enhancing the user interface. However, it has its limitations, such as the inability to interact directly with server-side resources or maintain state between pages. Furthermore, client-side scripts are exposed to the end user and rely on the user's device and browser capabilities, which can vary widely.

On the other hand, server-side scripts like ASP run on the server, interact directly with server resources, generate HTML before it's sent to the client's browser, and maintain a consistent performance regardless of the user's device or browser. Moreover, they are not exposed to the end user, offering a level of security and control that client-side scripting can't match.

Lastly, let's compare server-side scripting with the Common Gateway Interface (CGI), one of the earliest methods for generating dynamic web content. CGI scripts, often written in languages like Perl or C, are executable files run on the server in response to user requests. However, CGI has several limitations compared to technologies like ASP. For one, CGI creates a new process for each user request, which can be resource-intensive and slow, especially under heavy traffic. In contrast, ASP operates within a single process, handling multiple requests more efficiently. Additionally, ASP's integration with languages like VBScript, its built-in objects, and its compatibility with COM and ADO make it a more feature-rich and developer-friendly option for creating dynamic, interactive websites.

In conclusion, server-side scripting is not just an optional skill in modern web development—it's a necessity. By bridging the gap between client and server, maintaining state across user sessions, and delivering dynamic, personalized content, server-side scripting is key to creating robust, interactive web experiences.

Common Pitfalls and Maintaining Security

While server-side scripting offers a vast array of functionalities, it is also a field riddled with potential pitfalls and vulnerabilities if not properly managed. Two crucial areas that developers need to be especially attentive to are security and performance.

Let's start with security, one of the foremost concerns in web development. One common security vulnerability associated with server-side scripting and database operations is SQL injection. SQL injection occurs when an attacker can insert malicious SQL statements into a query. This could happen if your ASP script takes user input and directly incorporates it into a SQL command. The example above, of a user registration form, is actually vulnerable to SQL injection. Can you see why?

For example, consider an ASP page that accepts a user ID from the client, and then uses it to query the database:

userID = Request.QueryString("id")
sql = "SELECT * FROM Users WHERE ID = " & userID

If an attacker provides 1 OR 1=1 as the user ID, the SQL becomes SELECT * FROM Users WHERE ID = 1 OR 1=1. Since 1=1 is always true, this query would return all users!

How can we mitigate such attacks? By sanitizing user input and utilizing parameterized queries. Parameterized queries allow you to define SQL code with placeholders for each parameter. The actual parameter values are then passed in separately, ensuring they are treated as literal values rather than part of the SQL command:

set cmd = Server.CreateObject("ADODB.Command")
cmd.ActiveConnection = conn
cmd.CommandText = "SELECT * FROM Users WHERE ID = ?"
cmd.Parameters.Append cmd.CreateParameter("@id", adInteger, adParamInput, , userID)
set rs = cmd.Execute

In this case, even if an attacker tries to input a malicious string, it will be treated as a literal string value, not as part of the SQL command, hence preventing SQL injection.

When it comes to performance, managing server resources effectively is key. Server-side scripts that interact with databases can be resource-intensive and slow, especially when dealing with large volumes of web traffic. One way to manage this is to ensure that your scripts are optimized. Avoid unnecessary database calls, use appropriate SQL queries, and close any database connections as soon as they're no longer needed. These best practices ensure that resources are freed up quickly, ready to be allocated to new incoming requests.

Another approach is to use paging techniques to limit the number of records returned by a single request, hence reducing the load on the server and speeding up response times. For instance, you might only return ten records at a time, and then provide 'Next' and 'Previous' buttons so users can navigate through the data:

sql = "SELECT TOP 10 * FROM Users WHERE ID > " & lastDisplayedID

Caching is another strategy to consider. By storing the results of expensive operations or frequently accessed data in memory, you can avoid the need to repeatedly retrieve the same data or perform the same operations, resulting in performance gains.

Handling large volumes of web traffic can also involve strategies like load balancing, where incoming network traffic is distributed across several servers to ensure no single server becomes overwhelmed. Additionally, creating efficient code, optimizing database queries, and making judicious use of caching can significantly enhance the performance of your web application.

In conclusion, being proficient in server-side scripting with technologies like ASP involves more than just knowing how to create dynamic web pages. It's equally important to be aware of the potential pitfalls and how to navigate them, ensuring your web applications are not only functional, but secure and performant too.

Wrapping up

In conclusion, Active Server Pages provide an excellent platform for developing dynamic web applications. While client-side technologies like HTML, CSS, and JavaScript handle the look and feel of a website, server-side scripting with ASP empowers developers to deliver a more personalized, interactive experience.

Web development is a journey, and ASP is just one of the many tools you'll come across. So, dive in, experiment, and continue to hone your skills. The more tools you have in your belt, the more capable you'll be in meeting the needs of the ever-evolving World Wide Web.