Seeing Double, Detecting Duplicate Logins with Flex and ColdFusion...
I'm working with Kevin Kazmierczak on a Flex and ColdFusion project with Universal Mind and the need arose for us to be able to detect duplicate logins. Specifically, if a user logs in a second time without logging out of their initial session, we need to know. If the user does login twice, their ColdFusion session needs to be killed and they need to be logged out of the Flex application.
I'm going to detail the ColdFusion/Flex Data Services side of things and Kevin has written about the Flex portion on his blog.
The ColdFusion portion ended up being very simple, yet, very effective. We created an application variable called usersLoggedIn and made it a structure. This is done in the onApplicationStart method of Application.cfc.
Every time a user logs in, we store the user value object in the usersLoggedIn structure with their username as the structure key. We also added a unique session id to the user value object. We are using a UUID for this unique id.
<cfset application.usersLoggedIn[ arguments.userName ] = userVO />
</cflock>
Now, we need to be able to tell the Flex application when we detect a duplicate login. This is where we leveraged Flex Data Services. We're using the Flex Message Gateway (NOTE: ColdFusion Enterprise is required to leverage the Flex Message Gateway) to send a message to Flex clients when we detect a duplicate login.
<cfset msg = StructNew() />
<cfset msg.body = "Double Login Detected" />
<cfset msg.headers = StructNew() />
<cfset msg.headers.SESSIONID = application.usersLoggedIn[ arguments.userName ].sessionId />
<cfset msg.headers.COMMAND = "logout" />
<cfset msg.destination = "ColdFusionGateway" />
<cfset SendGatewayMessage("Flex2CF",msg)/>
</cfif>
When a user logs in, we are checking to see if they are already in the usersLoggedIn structure. If they are, we construct a message to send to the Flex clients with the users unique session id.
If you need help setting up the Flex Message Gateway, check out the Adobe docs. No need for me to reinvent the wheel.
That's all from the ColdFusion side of things, if you want to see what happens in the Flex application, head on over to Kevin's blog.
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Really nice tips!
will try to keep it in my mind
thanks!