CAS Distributed Ticket Registry ?

[Dan Mindler]

Hi Frank-

I believe the release included (un-tested) support for distributed EhCache. Our tests indicated problems under even a low amount of traffic. Therefore, Scott was working with others in supporting other implementations:

Scott Battaglia wrote:
> We're currently testing a JBossCacheTicketRegistry that performs much 
> better than the EhCache ticket registry.  Its scheduled to be included 
> in 3.1


> Another possibility could be the jdbc based ticket registry on CASM. 
> Any opinions ?

We've also considered a backend db (oracle here) to support clustered CAS servers. The two obvious solutions seem:

1. distributed caches
2. database backend

I like distributed caches since it is generally light-weight though I'm not sure how it will scale with the number of servers/traffic increasing. Assuming you have a DB backend available/scalable, this seems to support a large number of CAS server front-ends though the DB will be hit pretty hard.

In the end, we are trying to do two things: 

a. insuring availability of the CAS session - if one CAS server goes down or a request goes to another CAS server, the ticket is available for validating

b. insuring scalability of the CAS service - adding additional CAS servers to increase capacity


Note that item "b" plays into item "a", i.e., adding a second (or third) CAS server requires the ticket be accessible (through a distributed registry or db).


There is a third option that we considered. It could be possible to generate tickets with a suffix identifier, then configure HTTP request routing to the CAS servers (through a content switch or apache) to inspect the Request URIs and/or cookies for this identifier and route to the correct CAS server. This insures scalability of the CAS service (item b), though it does not insure availability of the CAS session (item a). This seemed more difficult to configure/maintain in production, so we stopped looking into this.

Anyway, Scott should be back from holiday in a few days, so he might be able to shed more light on this topic.

Dan



Frank Taffelt wrote:
> Hi,
> 
> in the release notes for the CAS Server 3.0.5 is the new distributed Ticket 
> Registry feature mentioned. Could someone elaborate more on this topic, 
> mainly how to configure and use it ?
> 
> I want to use CAS now in a loadbalanced enviroment and i'm trying to figure 
> out how to realize this. Maybe the distributed ticketregistry could help 
> here. Another possibility could be the jdbc based ticket registry on CASM. 
> Any opinions ?
> 
> Thanks,
> Frank 
>