Ask a Jedi: Copy session values from one application to another

Chong asks:

I am trying to copy a session variable from one application scope to another. Could you please enlighten me if this is possible and what is the best practise method for doing so?

The short answer to this question is no. There is no defined way of doing so. In fact, working with Applications and Sessions at a high level is something that ColdFusion doesn’t support in general. The ServerMonitor API gives you some access into this, but I’ve always wished ColdFusion made this more formal. For example, I think I should be able to do the following:

<cfset someapp = getApplication("someotherapp")> <cfset thesessios = someapp.getSessions()>

Now you can do this via undocumented API calls, but to me, that isn’t a real answer.

So considering that we can’t get access at a level like that - how can we solve the problem anyway? Here are a few ideas.

  • One possibility is to use cookies. Assuming both applications are on the same site, or perhaps the same root site, then a cookie could be used so the application A could 'speak' to application B. Cookies aren't 100% safe of course, but for sending simple messages it could be used. Technically this only works though if the user returns to B.
  • You could use database tables to store the information. Let's say app A and app B share a common DSN. You could easily record a message when in app A that app B will pick up. The issue here is connecting a session in app A to a session in app B. You need some unique value, like an email address, that both applications would be able to use to sync up the users.
  • You could use the Server scope in a similar fashion. This has the drawback though of losing the data if the server restarts.
  • Another option would be to perhaps consider migrating the separate applications into one main application. Each 'sub app' can handle keeping its own data separate into a particular portion of the Application and Session scope. </ul> Anyone else doing this? In general I've never had to worry about it. I ran into this a bit at RIAForge. RIAForge uses my blogware, forum, wiki, and bug tracker apps. (Geeze, when do I have time to play GTA??) Each of these applications have their own sessions and application scopes. In order to ease the process for users on the site I used my own hacked up SSO (single sign on) code. This doesn't copy session values over, but basically tries to re-authenticate the user in the new Application space. Not the best code I've written, but it works (afaik).
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