John Garmany
The Oracle Web Cache is a powerful tool and one that I see few organizations taking advantage of it ability to cache dynamic documents.
A dynamic document or object is one created from data and is valid only as long as the data does not change.
It's the "does not change" part that makes caching dynamic objects difficult.It of course takes planningin both your application development and database model.
While you still have to determine when an object is no longer valid, Oracle provides some simple tools to perform the actual cache invalidation.
The Web cache listens on an invalidation port (mine installed on 4002) for a simple HTTP POST message.The message can come from a terminal, the application, or the database.
In PL/SQL the WXVUTIL package contains the procedures to send an invalidation message to the web cache.
First, the package must be loaded in the database.It is provides in the webcache/toolkit directory.
/webcache/toolkit/wxvutil.sql.
[oracle@appsvr toolkit]$ pwd
/opt/oracle/portal904/webcache/toolkit
[oracle@appsvr toolkit]$ ls -l
total 104
-rw-r--r--1 oracle oinstall672 Jul 112003 invalidation.dtd
-rw-r--r--1 oracle oinstall65389 Nov 122003 jawc.jar
-rw-r--r--1 oracle oinstall 70 Jul 112003 README.toolkit.txt
-rw-r--r--1 oracle oinstall 4348 Jul 112003 WCSinvalidation.dtd
-rw-r--r--1 oracle oinstall 6083 Jul 112003 wxvappl.sql
-rw-r--r--1 oracle oinstall10757 Jul 112003 wxvutil.sql
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Notice this is the application server (or web cache if on a separate server) ORACLE_HOME, not the database ORACLE HOME.
After the scripts are run you can create triggers on the underlying tables of the dynamic objects.When the database executes a DML operation on the table (INSERT, UPDATE or DELETE), the trigger invalidates the cached objects based on the table data.
CREATE OR REPLACE TRIGGER PRODUCT_INVALID_TRIG
AFTER DELETE OR INSERT OR UPDATE on PRODUCT FOR EACH ROW
BEGIN
wxvutil.invalidate_reset;
wxvutil.invalidate_uri('/MainApp/prod_list.jsp', 0,
null);
wxvutil.invalidate_exec('web.appsvr.com', 4002,
'oracie123');
END;
/
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You can invalidate a single object (as in the example above) or multiple objects.
wxvutil.invalidate_uri('/MainApp/prod_list.*', 0, null);
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