Hi John,
- Oracle documentation says WebKit has an in-memory cache which can be
overridden by ResponseCache, this is not the case.
http://docs.oracle.com/javase/8/javafx/embedded-browser-tutorial/overview.htm#JFXWV135
-- "Other features". Explained below.
- JDK-8014501 states the problem, but has been flagged "not an issue". Why is
it not an issue?
Handling network cache within the webkit engine would be more efficient
rather than in java.net.ResponseCache. Currently its marked as Enhancement and
will be taken forward based on priority.
- signifant coding around "URL.setURLStreamHandlerFactory" and "URLConnection"
interception produces a functional cache with significant performance gains,
but is undone by problems deliberately introduced into URLLoader code.
i can answer for "deliberately introduced into URLLoader code." :
Webkit has 3 layer of cache (Memory and Disk based) Memory Cache :
1. Network level : storing raw network data, But this feature is not
implemented for our javafx port.
[Its by default provided in webkit2, JavaFX uses single process model
not the webkit2]
2. Cached resource for images, scripts, stylesheets, xlsstylesheets and
fonts (all resource decoded)
3. Page Cache (Entire DOM tree is cached, except the main page)
This can be tested with Page forward and Page backward.
"URLLoader code was setting setUsesCaches(false)" was added while
fixing JDK-8112030, where webview had duplicate RAW data (in ResponseCache) and
Decoded data (2 and 3 from above) inside the webcore. We should have updated
our tutorial well after this fix.
If you have considered below options, then please ignore
1. Making single page application and managing context with Z-Order.
2. Page navigation with Forward and backward.
3. lazy loading JavaScript files based on their first time usage
4. Choosing closest CDN for their 3rd party script files.
Thanks,
Guru
-----Original Message-----
From: John Maton [mailto:john201...@gmail.com]
Sent: Saturday, October 17, 2015 3:14 PM
To: openjfx-dev@openjdk.java.net
Subject: WebKit Cache
I have been trying to implement a disc based cache for WebView but with only
partial success, I am particularly trying to cache the .js javascript external
files which slow down the loading of javascript web pages a lot.
The Oracle documentation states that:
"When working with the WebView component, you should remember that it has the
default in-memory cache.
It means that any cached content is lost once the application containing the
WebView component is closed.
However, developers can implement cache at the application level by means of
the java.net.ResponseCache class. "
but this is not the case. I implemented an in-memory cache using the
java.net.ResponseCache class but it is very rarely used by WebView - from time
to time it stores and retrieves favicon.png from the cache - no performance
gain.
I confirmed by analysing the net traffic that WebView is not caching, thus
confirming what is stated in JDK-8014501:
"While navigating with JavaFX WebView component javafx.scene.web.WebView, it
was found, that every request retrieves all resources from the server each time
even if previous activities have just retrieved the resources. This behaviour
was verified by capturing and analyzing the network traffic.
The performance impact is considerable. "
nothing seems to have come out of JDK-8014501, so I then wrote a cache handler
using "URL.setURLStreamHandlerFactory" to intercept all URLConnections to the
default sun handler. I had some success with this and was able to cache .js
javascript files and increase performance significantly, but there were bugs on
a few web sites, notably Outlook's email.
On looking into the way my code was handled, I found for example that the
URLLoader code was setting setUsesCaches(false) with the following comments in
the code (at line 279 of URLLoader.java in current 1.8.0_66 code):
// Given that WebKit has its own cache, do not use
// any URLConnection caches, even if someone installs them.
// As a side effect, this fixes the problem of WebPane not
// working well with the plug-in cache, which was one of
// the causes for RT-11880.
So can somebody out there please give me a heads up on what is really going on?
- Oracle documentation says WebKit has an in-memory cache which can be
overriden by ResponseCache, this is not the case.
- JDK-8014501 states the problem, but has been flagged "not an issue". Why is
it not an issue?
- signifant coding around "URL.setURLStreamHandlerFactory" and "URLConnection"
interception produces a functional cache with significant performance gains,
but is undone by problems deliberately introduced into URLLoader code.
Thanks in advance for any feedback,
John Maton
