Cache Expiry Question

ErkDog · 07-07-2005, 12:03 AM

I see that from the Daily JPL Thread cache expiration works in that XML.

My question is how does the cache behave for the main imagery sets.

For example, if I have a cache set to 1h.

Does that mean after an hour my client will arbitrarily download any imagery again?

Or does it listen to "Not Modified" HTTP Responses, and consequently keep and use the file that was downloaded?

Thanks

5of0 · 07-07-2005, 01:02 AM

Pretty sure it listens to the "Not Modified" message.

ErkDog · 07-07-2005, 04:01 AM

then if it listens to Not Modified, what's the point in putting a time on the cache? to completely skip the check for new data? until X period of time has lapsed ?

If X period of time has lapsed, does it honor Not Modified, download no data for X period again ?

5of0 · 07-07-2005, 05:33 AM

Here's how I understand it:
Normally, WW looks to the cache. If there's a file there, it loads it up. Otherwise, it downloads.
If the file is past expiry, it checks for a new file. If it gets a "not modified" message, it just uses the existing file.
If it doesn't get the "not modified" message, it goes ahead and downloads the new file, then loads it up.

At least that's what I've gotten, but I never have quite understood it completely.

07-07-2005, 01:02 AM	#2
5of0 Dabbling Geek Join Date: Jan 2005 Location: Washington State, USA Posts: 1,623	Pretty sure it listens to the "Not Modified" message. __________________ Note: The above statement is probably an educated guess, derived from much forum reading, IRC chatting, general curiosity, etc. Use at your own risk. Before asking, check the FAQ or search, and Ask a good question. Having problems? Make sure you have Managed DirectX and .NET Framework. Then check the Video Card Compatibility List

07-07-2005, 05:33 AM	#4
5of0 Dabbling Geek Join Date: Jan 2005 Location: Washington State, USA Posts: 1,623	Here's how I understand it: Normally, WW looks to the cache. If there's a file there, it loads it up. Otherwise, it downloads. If the file is past expiry, it checks for a new file. If it gets a "not modified" message, it just uses the existing file. If it doesn't get the "not modified" message, it goes ahead and downloads the new file, then loads it up. At least that's what I've gotten, but I never have quite understood it completely. __________________ Note: The above statement is probably an educated guess, derived from much forum reading, IRC chatting, general curiosity, etc. Use at your own risk. Before asking, check the FAQ or search, and Ask a good question. Having problems? Make sure you have Managed DirectX and .NET Framework. Then check the Video Card Compatibility List

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
WorldWindData.com - World Wind Cache Packs	f0urtyfive	Add-ons & Scripts	152	09-19-2012 07:58 PM
Basic Cache / Data Sets Question	HectorHector1970	Technical Support	3	04-07-2006 11:50 PM
Combining Cache From Multiple Computors	Ken Williams	Technical Support	4	08-01-2005 09:49 AM
About Cache and Data question	lightyear	WorldWind General	1	05-21-2005 05:14 PM
Cache files	cadmar	Technical Support	1	05-17-2005 08:22 PM

07-07-2005, 12:03 AM	#1
ErkDog Junior Member Join Date: Jul 2005 Posts: 16	I see that from the Daily JPL Thread cache expiration works in that XML. My question is how does the cache behave for the main imagery sets. For example, if I have a cache set to 1h. Does that mean after an hour my client will arbitrarily download any imagery again? Or does it listen to "Not Modified" HTTP Responses, and consequently keep and use the file that was downloaded? Thanks

07-07-2005, 04:01 AM	#3
ErkDog Junior Member Join Date: Jul 2005 Posts: 16	then if it listens to Not Modified, what's the point in putting a time on the cache? to completely skip the check for new data? until X period of time has lapsed ? If X period of time has lapsed, does it honor Not Modified, download no data for X period again ?

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)