1. High Availability - Clustering ColdFusion
Mike Brunt – Teratech
DDT229

2. High Availability - Clustering ColdFusion
From my experiences in the field I see ColdFusion being used in ever larger Enterprises. Typically these organizations either have clustered environments already or are considering moving to a clustered environment.
In this presentation we will cover all that I have encountered relating to clustering ColdFusion over the past 11 years.

3. High Availability - Clustering ColdFusion
Who am I, what am I and why am I here?
I have been using CF since 1996, version (dbml) and am still actively developing in CF.
I worked for Allaire-Macromedia as a ColdFusion-Spectra consultant.
Co-founded Webapper (SeeFusion crowd) carried on the Allaire-Macromedia consulting work.
Currently heading up the Server division of Alagad Inc.
I am here to talk about my experiences related to Clustering CF and JRun and to answer questions.

4. High Availability - Clustering ColdFusion
What is Clustering?
Consider Clustering from Day One
Software Clustering (Java – CF – JRun)
Hardware Clustering Considerations
Hardware and Software Clustering

5. High Availability - Clustering ColdFusion
What is Clustering - HA?
Load Balancing is a part of
clustering along with fail-over.
Often we here the term
“Load-Balancer” when
It should be Clustering
Device.

6. High Availability - Clustering ColdFusion
Consider Clustering from Day One.
Here are some important things we need to think about as we bring clustering into the picture.
Do we need more than one copy of the web site code, if so how do we replicate it make sure all code is synchronized in case a user is moved from the server they are on to another?
If we are using shared scope memory variables (session) what happens in the case where a user is moved from the server they are on to another? In the J2EE world we can mitigate this by using the “buddy” system but that is only available to us the ColdFusion Enterprise. Can we use Client variables, should we?
Are we connecting to third party devices such as databases, LDAP, mail etc. If so how do we deal with calling out from multiple web-app servers?

7. High Availability - Clustering ColdFusion
Software Clustering.
I recall that whilst working for Allaire with “Cluster Cats” the good practice maximum number of servers to cluster using Cluster Cats was eight. This was is the pre J2EE-JavaEE world where a single physical server could run only one ColdFusion server. Eight physical boxes is a very “comfortable” number in my experience.
As with the replicated code itself, where separate physical servers are used, it is important that all the ColdFusion Administrator settings are identical in each instance created. With the exception of Scheduled Tasks – Client Variable Purge
Also note that it is only the Session scope objects that can be shared among cluster members, using the ColdFusion Administrator.
Software Clustering in ColdFusion JRun clusters the instances only not the external web server.

8. High Availability - Clustering ColdFusion
Hardware Clustering Considerations
Hardware Clustering has pretty much the same needs/planning as Software Clustering.
Do we need more than one copy of the web site code, if so how do we replicate it make sure all code is synchronized in case a user is moved from the server they are on to another?
If we are using shared scope memory variables (session) what happens in the case where a user is moved from the server they are on to another? In the J2EE world we can mitigate this by using the “buddy” system but that is only available to us the ColdFusion Enterprise. Can we use Client variables, should we?
Are we connecting to third party devices such as databases, LDAP, mail etc. If so how do we deal with calling out from multiple web-app servers?
Once again I recommend RoundRobin with Sticky Sessions.
One very important point, if the Hardware Clustering device is “pinging” a template on the server/instance make sure it is not also causing lots of code- processes to run. I have seen that bring applications to their knees.

9. High Availability - Clustering ColdFusion
Clustering Algorithms
RoundRobin

10. High Availability - Clustering ColdFusion
Clustering Algorithms
RoundRobin
With Sticky Sessions

11. High Availability - Clustering ColdFusion
Clustering Algorithms
Weighted RoundRobin
Random Weighted

12. High Availability - Clustering ColdFusion
Q & A Time