Automate population of DMZ WebCache

Question

I have writen a package that makes specific http requests to our DMZ server using the SYS.UTL_HTTP package functionality. With the aim of populating our DMZ server webcache after a batch load of new data.
I have noticed the http request made by the UTL_HTTP package is not logged the same as an identical http request made by a Browser in the http log. Below is a copy of the log tail for each
FROM UTL_HTTP package:
SELECT utl_http.request('machine_name/JournalDetail.html?PubID=104&Precis=SC')
FROM DUAL;
in which the following is logged in the http log on the DMZ server:
[IP ADDRESS]- - [14/Feb/2002:11:17:34 +0000] "GET /JournalDetail.html?PubID=104&Precis=SC HTTP/1.0" 200 34008 "-" "-"
FROM IE:
URL = http://machine_name/JournalDetail.html?PubID=104&Precis=SC
in which the following is logged in the same http log:
[IP ADDRESS] - - [14/Feb/2002:11:18:08 +0000] "GET /JournalDetail.html?PubID=104&Precis=SC HTTP/1.0" 200 34008 "-" "Mozilla/4.0 (compatible; MSIE 5.5; Windows NT 5.0)"
Webcache doesn't seem to recognise the UTL_HTTP http request as such, even though it executes successfully from my package. It doesn't match it against the corresponding configured webcache rule. Has anyone done something like this?...Am I on the right track here?... how else may it be possible to send cachable http requests from the database (preferably a trigger), to the DMZ webcache in order to force new data to be cached?

Answer 1

here is the other relevant line from the event log
Insertion not done for /blah.html?ID=104. Reason: Response and request cookies don't match. Shaun,
I presume you are using Web Cache 2.0.0.x as in iAS 1.0.2.2 release.
What you have encountered is an expected behaviour in Web Cache 2.0.0.x. Here is what happened. This JServSessionIdawg cookie, which seems to be a JServ session cookie is set by JServ if your request does not have such a cookie. Your UTL_HTTP package obviously does not send such a cookie, but your browser does since it caches cookies.
Now what does that mean to Web Cache? In 2.0.0.x and earlier versions, Web Cache is "protective" in this case. If it sees a cookie set from the response but not in the request, or if the cookie values are different in the request and in the response, it would consider that this request has caused some state changes at the backend server, so it would not cache the response, thinking the request has side effects. There is an exception to this. If this cookie is defined as a session in the Session Definition, then Web Cache will only consider the response non-cacheable if the request does not have the cookie but the response does. In other words, if the request and response merely have different values in this "session" cookie, Web Cache does not care.
So, so solve your problem, since this cookie value probably changes as the session expire, you can send the correct cookie value from the request in UTL_HTTP. What you can do is, define this cookie as a "session", which you probably are already, and then, send this cookie with any cookie value in your UTL_HTTP request. If this random cookie value won't cause your application to freak out except for a new cookie value, then the response will be correctly cached in Web Cache.
By the way, I thought you might be interested in knowing that we have disabled this implicit protectoin feature in the upcoming iAS 9.0.2, but it oftens causes problem under the cover. If you want such protection, you can still do that by setting Session-Related Caching Rules (force request to be cacheable, non-cacheable based on the existing of cookies in the request).
Hope this can solve your problem. Good day!