The HTTP protocol is quite simple. But many of us under-use it, programmatically speaking. There are many very simple performance mechanisms that are often forgotten. Many developers go for disabling HTTP caching completely, as they often don’t understand how to use it, and because it can cause weird bugs when used incorrectly.
But so much things are cacheable: pages, images, CSS, JavaScript, even many REST web services! Yes, even in this social web era where content changes faster than you can write, there’s still plenty of slow changing information, such as home pages, or lists of countries, regions and cities.
Efficiently using caching translates into:
- Better response and loading time
- Decreased load on the server
- Better user experience
This article aims to present a simple explanation of the HTTP protocol and proper use of HTTP caching.
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If you played with the pretty cool Amazon Web Services, you probably started off fetching a sample off the Developer’s Connection pages. At least, I did.
One cool sample for Simple Queue Service is the one by Justin@AWS. But (you saw it coming, I suppose), being anti-PEAR (for many reason, such as dependencies, weight, version conflicts, non-catchiness of the name, fructose intolerance, etc.), I just couldn’t leave the sample like that. Yes, this is me again reinventing the wheel.
The original library depended on two PEAR components:
Update (Dec 20, 2008): The AMF0Parser library has been updated to better handle broken AMF0 packets. The FLVInfo2 library PHPDoc has been updated.
Update (Aug 15, 2008): The AMF0Parser library has been updated to support the Date type in the metas, added among others by the “inlet media FLVTool2″ tool.
Update (Jun 11, 2009): The project has been moved to Google Code. MP4Info, an F4V file (or more genericaly MP4 file) class is also available: check out blog post and project at Google Code.
If you’ve done Flash banners or micro-sites that embed video with cue points for synchronization before, you know that it’s a pain in the arse. There doesn’t seem to be any tool around to modify the damn points once the file is encoded, so you’ve got to re-encode the file over and over to have your things synced correctly.
If you’ve tried to reverse engineer the FLV format before, you know that it’s a pain in the arse as well. The AMF0 format is anything but intuitive, and the documentation has been lacking for a long long time — although there’s apparently an SDK now. Luckily, there was OSFlash, and SabreAMF and AMFPHP that could be used as a documentation source.
If you recognize yourself, this might be your lucky day. After many hours of trial and error, I’ve finally been able to reverse engineer it, and to build a library that extract essential FLV information, reads the Meta, and allows you to write them back — including the cue points.
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