Periodic refresh of a servlet..?

Question

Hai people,
I have an appliaction scope object which is created using setAttribute mehod servletContext object. and the same can be retreived using getAttribute method of servletContext object.
I need to update the application scope object for every specified time interval. How can i periodically refresh my servlet such that my application scope object gets updated !! ??
Awaiting for ur replies !!
Thanks in advance,
Mani.

Answer 1

Hello,
We are also very interested in such feature.
We periodically query some backend databases on their System Change Number (ora_rowscn) to discover inserted and deleted data. The scheduling is currently done with a Spring Framework Container that is embedded in the grid (1) but we would be very interested in having such scheduling integrated in the CacheStore API. This would help us to prevent execution of the same loading task on each node of the grid.
Our pattern today is :
1. create a Named Cache called "cache-loader" to:
** store the context of each loader (last-load-time, last-integrated-system-change-number, etc)
** prevent concurrent execution of a loader using an entryProcessor to send the task on the active node that holds the context
2. Associated each loader ("my-backend-1", "my-backend-2", etc) a key and context stored on the "cache-loader" NamedCache
** Sample : key="my-backend-1-loader", value = MyBackend1LoaderContext[lastExecutionTime,lastIntegratedSystemchangeNumber, ...]
3. Develop an EntryProcessor for each loader (e.g. "my-backend-1-loader") that queries the backend database using the last system change number to retrieve the modified data
4. Schedule the invocation of the the loader EntryProcessors via SpringFramework on each node of the grid
We are aware that our approach does not scale well, that the EntryProcessors are over invoked (once per node of the grid instead of once for the whole grid) . Our trick is the serialization of the entry processors, we look at the last execution time and decide to skip the loader's business logic if this is an over-invocation.
If the number of nodes of the grid increases to numbers that would make the over-invocation problematic, we will schedule the invocations on an external component but we prefer to group all the grid related business logic in the grid.
Cyrille
Cyrille Le Clerc
[email protected]
(1) http://coherence.oracle.com/display/COH35UG/Integrate+CacheFactory+with+Spring