Administering Browser-Based Caching
This section provides an overview of browser-based caching and discusses how to:
Implement homepage caching.
Control navigation pagelet caching.
Implement PeopleSoft page caching.
A modern web browser can cache the information that it receives from a web server in several ways. Its preference settings determine how much storage space to use for caching, as well as the criteria by which it should refresh its cache.
How the Portal Controls Browser-Based Caching
If the browser is accessing a straight HTML page, it caches the page as a whole. If it's accessing a frameset, it caches the individual frames in the frameset so that each frame's content can be refreshed independently.
Rather than depend on users to enable and set the timing criteria for caching, PeopleSoft portal technology takes advantage of a feature of HTTP. The portal web server can specify a caching interval in the HTTP response header of the HTML page or frame content that it delivers. The browser applies this value to determine when to stop using its cached copy of the data and request the most recent version from the server.
Note: Even when the browser requests a fresh copy of an HTML page or frame content, the portal web server controls whether the content it sends is cached data or fresh data based on its own caching settings.
When to Disable Browser-Based Caching
The caching system increases system response performance in typical production environments in which users access the portal web site by using computers that have been assigned specifically to them or computers that they own. However, some environments don't conform to this scenario.
You should consider disabling browser-based caching in these environments:
Any environment in which multiple users access the same computer.
These include kiosk-type environments, as well as corporate hoteling environments, in which multiple users access the same machine. Users might access the same machine within minutes of each other before the browser cache for the previous user times out. Security is enforced in this situation, but the new user may be confused by an inability to access certain items.
A development or testing environment.
When content references are created or changed for a portal during development or testing, the new data might not appear to be immediately available due to caching.
Any environment in which you are using web server-based navigation caching.
In a PeopleSoft portal, a homepage is a combination of portal content elements that are assembled by the portal and delivered as a single HTML page, which is cached on each user’s browser.
Based on the configuration that you specify, the portal enables or disables homepage caching by using the homepage's HTTP header. If caching is enabled, the header also conveys the time interval before the web server is accessed again to get a fresh homepage. The browser does not access the web server after it initially receives the homepage until the specified interval elapses. You can also specify whether a particular browser model and version should use or ignore the caching information in the header.
In any case, if a user clicks the browser’s Refresh button, the homepage is accessed from the web server again, overwriting the homepage that is cached on the browser and restarting the interval counter. If any of the content is cached on the web server, the browser is refreshed from the server cache.
Enabling Homepage Caching
Important! Caching applies to classic homepages and pagelets only, and not to fluid homepages.
You enable homepage caching for a site by selecting the Cache Homepage check box in the On the Browser group box of the Web Profile Configuration - Caching page. When this check box is selected (the default value), two related page elements become editable:
Homepage Stale Interval.
When the Cache Homepage check box is selected, the following occurs:
All non-component-based pagelets will be cached on the browser by default unless the pagelet has a PORTAL_NOBROWSERCACHE content reference attribute set to Y.
Component-based pagelets will not be cached on the browser by default unless the pagelet has a PORTAL_NOBROWSERCACHE content reference attribute set to N.
Important! Do not enable homepage caching for any component-based pagelet that uses interactive processing mode.
When this check box is deselected, any PORTAL_NOBROWSERCACHE content reference attributes are ignored.
Specifying the Homepage Stale Interval
Specify the homepage caching interval for a site by entering a value in seconds in the Homepage Stale Interval field in the On the Browser group box of the Web Profile Configuration - Caching page. When the specified interval elapses, the browser sends a new request for the homepage to the portal web server the next time a user accesses the homepage. The default value for this field is 1200.
Disabling Caching for Selected Browsers
Because browsers don't all process HTML in exactly the same way, you might need to disable homepage caching for selected browser versions. This can be useful if you have one or two supported browsers and want to disable caching for nonstandard browsers that could pose an administration problem.
To disable homepage caching for a browser version, add a row to the Browsers grid of the Web Profile Configuration - Caching page, enter the browser's user agent ID, and select the Cache Home Page check box for that row. Homepage caching is enabled for all browser versions except those with this check box deselected, regardless of whether they're listed in the grid.
Note: As a convenience, several well-known browser types are included as sample rows in the configuration. All of the sample rows have homepage caching enabled by default.
When you use the portal menu to access target content other than your homepage, the portal delivers that content within a frameset. The portal header, menu, and target content regions are independent and can be managed separately by the browser. The menu region contains the portal's navigation pagelet, which can be cached on the browser with the user scope.
Without caching, every time the user clicks a menu folder, the browser requests a new copy of the navigation pagelet from the portal web server, which can significantly affect performance. With caching, the browser saves all of the menu states that are generated by user activity and can immediately restore them on demand.
Users manage navigation pagelet caching by using the Time page held in cache personalization option to specify a caching interval.
To specify a caching interval:
In PeopleSoft Pure Internet Architecture, select
On the Personalizations page, click the Personalize Option button for general options.
Enter an override value in minutes for the Time page held in cache option and click OK.
The default value of this option is 900 minutes. To disable navigation pagelet caching, specify 0 minutes. The maximum value can be 525600 minutes, which is one year.
Note: For the new setting to take effect, you must delete the browser cache.
With caching in effect, any changes in the menu structure while the user is signed in to the portal aren't available until the user signs out and signs in again, or until the caching interval elapses.
PeopleSoft pages are application pages that appear in the target content region of the portal frameset.
Being able to control PeopleSoft page caching on the browser is useful for situations in which PeopleSoft applications are deployed to kiosk workstations where multiple users access the applications. Disabling caching means that users can't click the browser's Back button to view another person's transaction or to view any other sensitive data.
Enabling PeopleSoft Page Caching
You enable PeopleSoft page caching for a site by selecting the Cache Generated HTML check box in the On the Browser group box of the Web Profile Configuration - Caching page. PeopleSoft page caching is enabled by default.
With PeopleSoft page caching disabled, when users click the Back button they receive a data missing message in Netscape Navigator and a page expired message in Microsoft Internet Explorer.
Note: The side effect of turning off caching completely is degraded performance. For each new page, the system calls the database. However, PeopleTools offers a compromise related to browser caching in the form of navigation pagelet caching, which doesn't expose any sensitive information.
Specifying Supported States
When the browser caches a PeopleSoft page, it stores the state of that page, including any unsaved changes. With the page state in the cache, users clicking the browser's Back button see the cached page in the state that it was in when they last viewed it. The browser caches as many page states as its own settings for storing temporary data allow.
The portal also maintains its own cache of page states for each browser window. You can specify how many of these states the portal should consider valid and support for further interaction. This setting, combined with the number of states that the browser maintains, determines whether users can continue to work with previously accessed page states.
For example, if you specify that the portal should support two states, and the user clicks the Back button three times, any activity that requires refreshing the displayed page from the web server (such as field validation) fails, producing a page unavailable message in the browser.
You specify how many states the portal should support by entering a number in the Number of States Supported field in the On the Browser group box of the Web Profile Configuration - Caching page. The default value of this field is 5 states.