Brian and Jay OK, I've got a "working" implementation of OSCache for OJB. There are a couple of loose ends on methods/params that I'm unclear with for OSCache, so I'm waiting for a response from their mailing list before I post.
Hopefully today though, I should be able to have a working OSCache for you. Jason McKerr On Tue, 2003-07-22 at 11:19, Glanville, Jay wrote: > Jason, thanks for the reply. The answers to your questions are inline. > > > > Lemme get this straight first. Both the web and the desktop > > would have > > their own instances of OJB? > > > That's my impression at this point. > > > > The caching issue somewhat depends on your requirements. If > > you're in a > > highly "pessimistic" transactional environment, then there > > are a couple > > of options. You can, as you said, disable caching, or you can set the > > systems up to clear the caches regularly. > > > The concept of periodic-cache-clearing requires too much of this bottle of > head-ache pills: they allow for the opportunity of non-recreatable timing > bugs (user a makes a modification, but user b has to wait for the cache > clear to see it). It just leaves a bad taste. > > > > At NACSE, we run OJB in a heavily clustered/failover/load-balanced > > environment. To get around the problem that you are encountering > > (Caches being out of Synch) we decided to use a clustered/distributed > > cache. > > > > This ensures that the cache structures on different nodes are notified > > of changes in the cache structure. However, we are in a carefully > > controlled server only environment. I'm not sure if this > > would work for > > you, since the desktops would have to initialize, and synchronize the > > caches (through multicast) every time someone started their > > desktop app. > > > I'm interesting in learning more about your environment (the non-proprietary > aspects ;-) ). I might be able to learn something that can help my > architecture. > > > > Another question: What are the different apps for? For > > example: if the > > desktop apps are for entering/updating data for the web > > system, then why > > not disable caching on the desktop? If the web-system is more to > > display (more reads than writes) that input data, then it would be a > > more logical place for the cache. You can then flush the web > > cache, and > > update for input changes at the database. > > > Currently, we've limited things to three clients: a network-based service > (non-web), a restricted access web-service (exterior of firewall) and a > non-restricted web-service (interior of firewall). Now, the non-web service > is duplicated on a parallel machine (ok, that's 4 clients). Additionally, > we're looking at desktop client (possibly to aid in offloading work from the > web-services). Due to the fact that some clients would be outside of a > firewall, I'm not sure how much clustering would be able to help me. > > The web-services and desktop clients allow users to modify / add / remove / > control the services that the non-web service provides for them. Both also > communicate with the non-web service. > > > > So again, it is likely possible to do what you want. But it > > depends on > > your requirements. > > > Final requirement that has yet to be mentioned: we are not currently using > EJBs for communication between clients / services / etc. Data communication > is through the database, data change notifications is through an > RMI-broadcasting structure (that I REALLY, REALLY want to get rid of). > > I guess one of the ancillary things I was looking for was a way for a DB to > push information down a JDBC connection, thus allowing the clients to react > appropriately to the change of information. If such a thing actually > existed, then OJB would/should be using it for cache synch. Does anybody > know of any such architecture? > > > > > ps. If you're interested in the distributed cache, I think there is a > > contrib file somewhere for adding Tangosol Coherence support that I > > wrote. With the release this week of OSCache 2.0, I am also > > planning on > > writing a plug for using OSCache's distributed cache with OJB > > (Tangosol > > is expensive, OSCache is free). OJB also supports JCS, but I had real > > problems with it. > > > > Jason > > > Thanks for the feedback Jason. It is certainly appreciated. > > Jay Glanville > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
