How to use JESI template/fragment model to cache dynamic content
OracleAS Web Cache How-to
Date: October 22, 2003
How
to use JESI template/fragment model to cache dynamic content
After
completing this How-To you should be able to:
Know
about the JESI template/fragment model to cache dynamic content
Use
<jesi:template>, <jesi:fragment> tags
Introduction
Oracle
JESI tag library provides convenient interface to ESI tags and Edge Sides Include
functionality for Web caching. It provides two models to cache dynamic content.
Control/ Include model
Template/ Fragment
model
This How-To explains the template/fragment
model. In the template/ fragment model, the web page is split into separate cacheable
fragments. JESI template tag is used to enclose the aggregate of all cacheable
fragments. JESI template tag and JESI fragment tag are always used together. JESI
template model should be used, when a single page has to be split into separate
cacheable fragments. If the page need not be split into fragments, JESI control
tag can be used to cache the content.
Pre-requisites
for running the example
You will need the following
to run this example -
Oracle Application Server (9.0.3 or
above). This can be downloaded from here
Oracle JDeveloper (9.0.3 or above). This can be downloaded from here.
This is optional and required only if you wish to deploy from JDeveloper.
Description
Each
of the fragment and the content outside the fragments, i.e. the template are considered
to be independent cacheable objects. All these objects can have different cache
policies set. When the fragment expires, ESI processor built within OracleAS Web
Cache will request the origin server for that particular fragment.
The
example depicts the sales information system. The example displays sales information
page, which consists of sales summary for the current year and sales history showing
past sales records. For the current year, sales data will be streamed into the
system, hence sales summary content has to be updated frequently than the sales
history content.
Using the JESI template/fragment
model, the sales information page is split into two fragments. Sales summary fragment
which has expiration time of 60 seconds and sales history fragment which has expiration
of 300 seconds. For demo purpose, sales history fragment has been set as 300 seconds.
However these expiration values can be set to higher/lower values.
Following
is the code snippet used to split the content into separate cacheable fragments.
..... <jesi:template cache="yes"> ....
<jesi:fragment
cache="yes" expiration="60" maxRemovalDelay="0">
<%@ include file="salessummary.jsp"%> </jesi:fragment>
<!-- sales history --> <jesi:fragment cache="yes" expiration="300"
maxRemovalDelay="0"> <%@ include file="saleshistory.jsp"%>
</jesi:fragment>
..... </jesi:template>
The
cache poilcy for the template and the fragment is set by the cache
attribute. expiration attribute specifies how long the
cached object should stay in the cache and maxRemovalDelay
attribute specifies how long the document can be served stale after expiration.
expiration and maxRemovalDelay are specified in seconds.
Deploying
the Sample
The complete source code for this sample
is available here. This section discusses
the instruction to run the sample application
Step 1
Unjar
jesitemplate.jar using Winzip, or using the following
command:
> jar xvf jesitemplate.jar
This creates a directory jesitemplate.
Step 2
If you are using JDeveloper then, follow these steps
Open
Oracle9i JDeveloper and use File/Open option to select the
jesitemplate.jws from the jesitemplate directory.
Next, select Project/Make jesitemplate.jpr
from main menu.
Create an application server connection
Go to
Connections -> Application Server Connection. Right Click and click New connection..
In
step 1, enter connection name and select Oracle9i Application Server
In
step 2, enter user name and password
In step 3, enter Enterprise Manager's
host name, port number and Remote Oracle AS home directory(required only if deployed
on remote machine).
In step 4, click Next and Test the connection. Click
Finish button.
Now, Right click jesitemplate.deploy
and select Deploy to <connection name>, to the application server connection,
which you have created in the previous step.
Step
3
To deploy the application using EM. follow
the steps.
Go to EM web site -> default oc4j
home.,
Choose Deploy EAR file
Enter J2EE Application name, Click
the Browse button and choose jesitemplate.ear from
<SAMPLE_HOME>/deploy/jesitemplate.ear
Enter
the Application name as jesitemplate and click next
Enter URL mapping
as /jesitemplate and click Finish
Click Deploy to deploy the application.
Running the Sample
Access
the page on the browser, using the following URL
Bookmark
