Semi Dynamic Content

[Anon]

I am having trouble finding out a good way to implement a simple concept.

Web content isn't strictly DYNAMIC or STATIC. Some things change once a day, so why should each hit to the page access this same data over and over throughout the day.

Can PHP (or another technology) make available the static content and then regenerate the static content when a certain event happens (either on a time schedule or by using a semaphore).

Any thoughts, suggestions, or ideas are greatly appreciated.

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[Anon]

Updating or regenerating static html pages on a timed basis is easy.
Whether or not you want to use PHP for this depends on what other
tools you have available. The basic concept is to write a shell script
file that uses perl or whatever favorite language you like to generate
the page which is then written to disk. If you want to use PHP, you
can either install the standalone version (which is supposed to coexist
with mod_php but I've never actually tried that) or your shell script
can just use lynx or wget or whatever to access the php script that
accomplishes the task. You then put an entry for the shell script
into your crontab. Task accomplished!

Triggering the update by a semaphore (or, more generally, on any
kind of event other than the clock) is more complicated if only because
there's no unified model of how to sense the event.

Finally, there's a very interesting post around here from Steve
Yelvington describing a different kind of "semidynamic" content
very useful for news publishing and similar things, where static
pages are built out of the news database the first time the
page is requested. See:

http://www.phpbuilder.com/forum/read.php3?num=2&id=111360&thread=111358

[Anon]

Thanks Kirk, for all the good info. I'm in a similar situation and was thinking I'd have to 'preprocess' the rarely dynamic pages (the ones that probably won't change more than once a year) and take the database hits on the semi-dynamic pages (that change daily). The cron job is definitely a better solution, but ideally the pages would regenerate whenever the mysql database is updated. Any ideas on that?

[Anon]

Beth, you've put your finger on the tricky part of maintaining a cache system. If "right now" is important to you, the processes that update information in the core database need to trigger a "flush" of appropriate cache information. If "right now" is not important, then you can manage the situation by flushing the entire cache periodically. Since PHP is a programming language and not a content-management system, it doesn't provide that functionality directly, but it could be implemented in a system built using PHP.

You should give some thought to how caching applies to different types of information, and how pages can be decomposed into separately cacheable elements. On some Web sites it might be appropriate to have certan navigational elements that would be unique to a day cycle. Those elements might be built on demand out of a database, and placed into a particular cache area that would be flushed at midnight. Other elements (such as sitewide branding) might be maintained in a content-management system but could persist in cache until the designer decides to rejigger the look and feel. Some elements might be appropriately subjected to short-cycle time-based cache flushing (latest headlines, updated every six minutes) and others might have to be "right now" coherent with the core database.

The object of all of this would be to move into a content-management database all elements that site managers might want to update at their whim, while avoiding needless hits on the database.

[Anon]

Thank you, Kirk, for the solution you suggested. This simple solution will work well for our site.

As a database developer, I want to minimize unnecessary access to the database, yet I have been unable to find any suggestions on how people accomplish this.

Thanks again,

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