Wednesday, July 18, 2007

sql to list mutual funds

we don't know when the database may get updated. we only know it's very rare

Jingsong J. Feng if the change frequency is very low, create a trigger in the database, when data change, trigger a query, and update result

Jingsong J. Feng schedule Thread to run it every miniute or every 5 miniutes
Bin X. Tan/VEN... to update the local cache?
Jingsong J. Feng yes

Jingsong J. Feng oh, set a timeout variable -- Hibernate

How about an update/insert/delete trigger to send a GET request to our servlet and expire the cache immediately? The next visitor to the website would see the updated list fresh from the database.

If there's a jms broker, trigger can send a cache-expiry alert to the queue even when the web system is unavailable. When the web site comes up again, it receives the jms message and expires the cache?

Without a JMS broker, the GET request could update some persistent expiry-flag on the cache server. Even with frequent reboots, the cache server could check the expiry-flag periodically.

Q: Can a trigger send a GET?
A: yes

Q: Can a trigger be a jms client?
A: Not so common. http://www.oracle.com/technology/products/integration/bam/10.1.3/TechNotes/TechNote_BAM_AQ_Configuration.pdf
(AQ = Oracle Advanced Queuing )

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