Have you ever been logged into an application and had your session timeout, then when you log back in you are returned to a different place altogether?

This article deals with a way to mark where a user was in your application and return them to that location when they log back in. It also allows a user to deep link into an application. IE when they have a bookmarked link instead of being passed to the home page, they are passed through to their original destination.

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I stumbled upon an interested dilemma recently whilst building a search engine. The results of a search are returned, and can be viewed in a list or thumbnail view. The view toggle is a uses a JQuery function, so no persistent data is stored concerning a users current viewing option. The dilemma is how do you maintain the viewing mode across page reloads, such as for pagination, or filtering of the search results?

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A bug came up in an application that uses the CFchart tag to create flash charts.

On the initial load the charts display just fine, but if you refresh the page, or go back to it later to view the data the images error. They display like this:

There seem to be two potential reasons for this. The first is that the cache for the chart in ColdFusion has expired. It seems that by default the per request cache is for 5 seconds only, so if your template takes longer than this to run then you may end out with expired content before you serve it up.

To fix this try this, excerpt from the CFchart blog: 1. Stop the CF server. 2. Open \lib\webcharts3d.xml 3. You can increase the timeout for keeping the graphs in the cache by editing the minTimeout and maxTimeout attributes:

Change this to whatever values you want.(Values of minTimeout and maxTimeout are in milliseconds.)

Full article here: http://cfchart.blogspot.com/2005/06/image-expired-trouble.html

The second potential reason for this, and the more likely in this case is that the code is running on a clustered server. The error is cause where the CFchart tag generates a temporary file (swf, png, jpg) and serves that up to the user. When the user makes another request there is no guarantee that the request will hit the same server, so it will not find the temporary file, and throws the 'content expired' error message.

You could ensure that the content is served up correctly by tying the user to the server using session management, or more ideally set the temporary file to be written to a central server in a kind of CDN (Content Distributed Network) way.

I'm off to try both and see which one works!

I am a big fan of fusebox, I like the way it handles inheritance, and I love the fact that it instinctively lends itself to a modular approach.

Part of the strength in using fusebox is in knowing exactly when each of the framework fuse actions run, and just what sort of functionality you can embed in them. In this case I'm using the "Pre fuse Action" to perform a basic security validation on any fuseactions in that circuit.

Above is a blank prefuseaction, insert any code you want to perform on any of the other fuseactions in that circuit here. Note that it runs before the circuit action.

A basic session validation script could be something like:

In the code above I am checking for a valid session variables, and if it is not there sets an error message and redirects to the homepage.

This is a pretty basic "catch all - are you logged in?" type query, but if you have an administration circuit then it provides good basic fuseaction protection. I've extended it out one step further by creating a cfc call to this code which just returns true/false. Something like this:

I am currently extending this further with more robust security, and user roles and groups.