Handling session management effectively is crucial for maintaining performance, security and user experience of ColdFusion applications. This guide is aimed to help outline the best practices for managing sessions in ColdFusion and hopefully avoid unnecessary memory leaks, compromised data and of course user frustration.

What is session management?

Session management is a crucial aspect of web development that allows you to maintain user interactions and state within your application across multiple requests. In ColdFusion, session management enables you to store user-specific data, ensuring a seamless and personalized experience for each user.

For example, when a user interacts with a ColdFusion e-commerce website, they may add items to their shopping cart. These items are stored in the user's session, which is associated with the currently logged-in or anonymous user. Session variables make it possible to keep track of the user's cart items, preferences, and other relevant data throughout their visit.

Without session management, or if a user session expires, the stored data, such as the items in their cart, will be lost. This can lead to a confusing and frustrating experience for the user, as they may not see the items they previously added to their cart. To prevent this, ColdFusion provides a robust session management system that helps maintain user state and interactions effectively.

Handling Bots and Spiders

You may have heard of one or more of the terms bots, spiders, crawlers, or scrapers. While these are not legitimate users accessing your website, they do make requests to your website in order to obtain data and store information related to that data in their own systems. Often times, websites get more traffic from these bots and spiders than real users. If you do not handle sessions appropriately in your ColdFusion application, then it can cause an overwhelming number of sessions within ColdFusion and, therefore, a heavy memory allocation within the Java heap space. This could cause potential memory leaks, resulting in an eventual crash of ColdFusion.

So, how should you handle these bots to prevent performance issues with your ColdFusion service? Well, a long time ago, the answer you would have been told was to disable sessions for bots. This is not the recommended approach to handle these bots, as disabling sessions could cause unexpected errors in your application that depend on the session being active. Instead, it is recommended to limit sessions for bots to a lower threshold such as 2 minutes.

Since these bots do not utilize cookies, you can check for the presence of a cookie in your application. If a cookie is found, apply your standard session timeout (e.g., 30 minutes, as shown in the example below). If no cookie is detected, it is likely a bot request, and you can restrict the session timeout to a shorter duration, such as 2 minutes (as demonstrated below).

<!--- If no cookie is detected, then a shorter session timeout is applied. --->
<cfif StructKeyExists(cookie, "cfid") or StructKeyExists(cookie, "jsessionid")>
 <cfset this.sessiontimeout = CreateTimeSpan(0,0,30,0) />
 <cfelse>
 <cfset this.sessiontimeout = CreateTimeSpan(0,0,0,2) />
</cfif>

<!--- If no cookie is detected, then a shorter session timeout is applied. --->
<cfif StructKeyExists(cookie, "cfid") or StructKeyExists(cookie, "jsessionid")>
 <cfset REQUEST.sessionTimeout = CreateTimeSpan(0,0,30,0) />
<cfelse>
 <cfset REQUEST.sessionTimeout = CreateTimeSpan(0,0,0,2) />
</cfif>

<cfapplication name="myExampleSite"
sessionmanagement="Yes"
sessiontimeout="#REQUEST.sessionTimeout#">

By configuring a shorter session timeout for bots and spiders, the Java garbage collector, as defined in ColdFusion's JVM settings, will clean up these sessions more efficiently. This significantly boosts ColdFusion's performance by reducing the Java heap load, ensuring that ColdFusion remains readily available for legitimate user requests.

Configuring Secure Cookies

Secure cookies are a type of HTTP cookie that can only be transmitted over secure, encrypted connections (HTTPS). They have the "Secure" attribute set, ensuring that the cookie data is not exposed to potential interception or tampering during transmission between the client and the server. Additionally, setting the "HttpOnly" attribute prevents client-side scripts (such as JavaScript) from accessing the cookie, further enhancing security.

Without secure cookies, user data could be compromised, or the attacker could hijack the user's session, allowing them to gain access to the system as that user. So let's show how to enable secure cookies to prevent this:

component {

    // Application settings
    this.name = "myExampleSite";
    this.applicationTimeout = createTimeSpan(1, 0, 0, 0);
    this.sessionManagement = true;
    this.sessionTimeout = createTimeSpan(0, 0, 30, 0);
    this.setClientCookies = true;
    this.sessionCookie = {HttpOnly="true", Secure="true"}; // Sets the secure cookie

}

<cfapplication
    name="myExampleSite"
    sessionManagement="Yes"
    sessionTimeout="#CreateTimeSpan(0,0,30,0)#"
    setClientCookies="Yes"
    sessionCookie="HttpOnly, Secure" <!-- Sets the secure cookie -->
>