Thanks everyone for the posts. @Mike, I am still not convinced that using the Remote Notification Feature is really nessecary here. After all, there seems to be a JVM shared between webapps in Tomcat and the article posted seems to proof that there is a possiblity to share information between the webapps on a JVM level. So I think that using Remote Notification, which I understand to be designed for Cross JVM notification creates too much overhead.
You mentioned the possibility of sharing the DataContext between the webapps. I think I have to explore this possibility first, as this would have less overhead compared to the notification based solution. Currently I am using the org.objectstyle.cayenne.conf.ServletUtil.getSessionContext(request.getSession()) to obtain my DataContexts per request. If I could change the scope the DataContexts are stored to cross web app scope instead of session scope I could share the DataContexts between the two web apps. Assuming that I can setup the two webapps to share the same session Ids as described in the article. This might be a no go for me as the two contexts use different authentication realms - I have to check this. But even then wouldn't it be possbile to configure the cayenne shared cache to use this cross web context scope for its shared cache. Then I could use org.objectstyle.cayenne.conf.ServletUtil.getSessionContext(session) in the two web apps transparently and cayenne would refresh the DataContext from this shared cache in the background. Could somebody point me to where this shared cayenne cache is configured to have its scope? I assume it uses JVM static scope? @Malcolm, thanks for suggesting this alternative. If I understand you correctly you suggest to switch off the cayenne cache alltogether and use the jsptag based caching of the OScache project? The problem with this is that not all my responses are generated from jsptags. I have many ajax requests generating json responses without bothering the jsp container. Tobias On Thu, Jul 30, 2009 at 3:00 AM, Malcolm Edgar <[email protected]>wrote: > You can also use OSCache with Cayenne and have the cached queries > expire frequently, i.e. after 30 seconds > > regards Malcolm Edgar > > On Thu, Jul 30, 2009 at 6:36 AM, Mike Kienenberger<[email protected]> > wrote: > > Before you make your own custom solution, you might want to read up on > > Javagroup. It might not be a problem to use it in your environment. > > > > The main page starts off with this: > > > > http://www.jgroups.org/ > > ================================== > > JGroups is a toolkit for reliable multicast communication. > > (Note that this doesn't necessarily mean IP Multicast, JGroups can > > also use transports such as TCP). > > > > [...] > > > > JGroups comes with a number of protocols (but anyone can write their > > own), for example > > * Transport protocols: UDP (IP Multicast), TCP, JMS > > > > ================================== > > > > So even if the TCP version doesn't do what you need, you might find it > > easier to write your own Jgroup protocol than to write your own > > cayenne event bridge. It's more likely to be documented and there > > will be more examples/end users to ask questions of. There might even > > be a tomcat shared session protocol out there somewhere. > > > > > > On Wed, Jul 29, 2009 at 4:16 PM, Tobias > > Schoessler<[email protected]> wrote: > >> well i am reading this from the documentation: > >> > >> "... At the minimum, JMS setup requires a JMS server running, and > subjects > >> for each of the DataDomains to be configured. JavaGroups is peer-to-peer > >> library that is embedded into applications. Default configuration > provided > >> by CayenneModeler will work out of the box, provided that IP multicast > is > >> enabled on the network." > >> > >> for the JMS solution the JMS server setup is a problem > >> for the JavaGroups setup the "IP multicast is enabled on the network." > is a > >> problem > >> > >> so for the custom tranport mechanism that you mentioned I stumbled upon > >> this here > >> > >> > http://jee-bpel-soa.blogspot.com/2009/06/session-sharing-in-apache-tomcat.html > >> > >> which seems to describe cross context data sharing on tomcat web > contexts > >> > >> but is there any code to look at to see how a custom transport mechanism > can > >> be setup? > >> > >> Tobias > >> > >> > >> On Wed, Jul 29, 2009 at 8:28 PM, Mike Kienenberger <[email protected] > >wrote: > >> > >>> I've never set it up, but it's easily configurable. > >>> > >>> If you don't like the javagroups or JMS methodologies, you can define > >>> your own -- I don't know what tomcat app-data-sharing ability is > >>> available -- it probably depends on the container, but I don't > >>> remember reading about any in the past. > >>> > >>> However, the docs seem to indicate that using Javagroups is pretty > >>> painless with no external configuration to deal with. > >>> > >>> I have a Cayenne 1.1.x application I wrote that used remote > >>> notification internally to broadcast events between sessions, so I > >>> know it's not difficult to set up and define your own event > >>> broadcaster. My guess is that doing it for javagroups is pretty easy > >>> since it sounds like a matter of just filling in the forms on the > >>> modeler. > >>> > >>> On Wed, Jul 29, 2009 at 2:15 PM, Tobias > >>> Schoessler<[email protected]> wrote: > >>> > Thanks Mike, > >>> > > >>> > so the answer is yes, this can only be done using remote > notification? is > >>> > this correct? > >>> > > >>> > Isn't there a way to share the cache among two web application scopes > >>> > without going through the hassle of setting up remote notification? > >>> > > >>> > When the two webapps are running on the same physical machine, inside > the > >>> > same application server this seems overkill. > >>> > > >>> > Tobias > >>> > > >>> > On Wed, Jul 29, 2009 at 6:50 PM, Mike Kienenberger < > [email protected] > >>> >wrote: > >>> > > >>> >> Yes, > >>> >> > >>> >> Here's a Cayenne 2.0 document on it: > >>> >> > >>> >> http://cayenne.apache.org/doc20/configuring-caching-behavior.html > >>> >> > >>> >> For 3.0: > >>> >> > >>> >> http://cayenne.apache.org/doc/configuring-caching-behavior.html > >>> >> > >>> >> On Wed, Jul 29, 2009 at 12:46 PM, Tobias > >>> >> Schoessler<[email protected]> wrote: > >>> >> > Hi, > >>> >> > > >>> >> > is it possible to sync the cayenne cache of two web applications > >>> running > >>> >> in > >>> >> > the same tomcat? > >>> >> > > >>> >> > I observe one web app showing outdated data when the other is > >>> committing > >>> >> > updates. Both apps are using the same mapping configuration. > >>> >> > > >>> >> > Do I need to use remote notification for this? > >>> >> > > >>> >> > thanks > >>> >> > > >>> >> > Tobias > >>> >> > > >>> >> > >>> > > >>> > >> > > >
