Caching

[mk]

Do where's servers cache some of our stuff
somewhere? If so, can it be disabled so changes
I make on my server will propagate out?

Just now I made a change to both the Jin on
one of my pages and one of the images that
is loaded by that page. But there was no change in the page
displayed on the device (Nokia N95 running N95NSTL).
I power cycled the device but it still displays the old stuff.

And the really bizarre thing is that s265714bo2el01.uswlhm2.savvis.net
is requesting the new page from my server, yet the
device still displays the old page??

MK

[phillipr360]

MK,

If you do not want WHERE to cache your Jin page, simply use:

<jin cache="false">

at the top of your page. Similarly, if you do want Images to cached,
use:

<img src="Some_Image.png" cache="false"/>

WHERE does not cache Jin pages by default, though the MPowerPlayer
emulator may; that is why it is always a good idea to use
cache="false" in your <jin> tags. On the other hand, images ARE cached
in WHERE unless cache="false" is specified. According to Gil, this is
because most widget-related Images (such as the Soft Key Images) do
not change once the Widget is finalized and it takes considerably less
time to load cached Images in general.

If you want to remove cached Images and/or Jin pages, simply select
the "clear cache" menu option on the widgets page of the MPowerPlayer
Emulator and exit WHERE. The next time you start WHERE the new Images
(and/or Jin pages) should display properly. Similarly, to clear the
cache on a real Handset (such as the Nokia N95), open the Menu on the
WHERE home page, select "settings" -> "Advanced" -> "Clear Cache",
click the button to clear the cache, and restart WHERE.

- Phil

[mk]

Thanks for the quick reply.

I think the unusual behavior I observed may have come because

1. I had a header that mistakenly went out as

<jin stack="" cache="false">
or
<jin stack="0" cache="false">

which your parser may have had trouble with, leading it
to mistakenly cache the page (though I still don't understand
why I saw a hit on my server).

2. When you use "settings" -> "Advanced" -> "Clear Cache",
it says something about refreshing widgets, and then brings
you to the main where menu. As you point out, you have to
actually restart where at that point, but I didn't know that this
morning.

As far as you know, will cached images always persist across
- restarting Where
- power cycling the device
or is it device dependent?

Is anything cached on your servers, or is it all in the device?

Thanks,
MK

[phillipr360]

MK,

1. As far as the <jin> tag goes, you should use:

<jin cache="false">,
<jin cache="false" stack="true">,
or <jin cache="false" stack="false">.

The "stack" attribute is optional and defaults to true. When set to
"false", it simply does not store the page on the stack, which means
that the "back()" will skip it when you try to go Back. Using an empty
stack attribute may very well have been why your Jin page was cached,
though you would need to check with Gil on that.

2. It is true that you need to restart WHERE after clearing the cache
for the change to fully take effect. In general, it is always a good
idea to restart WHERE after the "Refreshing Widgets..." Layer appears
on the WHERE home page unless you just added/removed a new widget
under "Manage Widgets". The reason we don't force users to restart
WHERE is in case they want to continue using WHERE after clearing the
cache; in general, we don't want to force users to exit/restart WHERE
unless it is absolutely necessary (such as during the Web Activation
process).

3. Images cached in WHERE are stored in your Handset's virtual memory.
They will remain cached until the cache is cleared, either by "Clear
Cache" or by an event that automatically clears the cache (such as the
cache being full). As a result, cached images will persist when WHERE
is restarted or power cycles. As a result, to replace a cached image,
you will either need to do "Clear Cache" or use a different Image URL.

- Phil