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https://issues.apache.org/jira/browse/TAP5-769?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Ben Gidley updated TAP5-769:
Attachment: 0004-TAP-769.patch
0003-TAP-769.patch
0002-TAP-769.patch
Here is a patch that implements a solution for this.
This changes the DocumentLinker and RenderSupportImpl so that scripts can be
'grouped' prior to assembly into a single script.
The default behaviour now is to create one 'group' from the
ClientInfrastructure stack and a second group from everything else.
This should address a good percentage of this problem raised in this issue.
Further enhancements that could be made
* Add method to render support to users to create their own groups
* Add a contribution point (similar to that provided by
http://tapestry.formos.com/projects/ioko-tapestry-commons/tapestry-javascript/)
could be provided to allow inclusion of stacks on certain pages
* A further contribution to allow replacement for a stack rolled up javascript
with a 'production' one e.g. from a CDN.
This patch does not address this issue of the length of the filename for the
'stack'. I can't see an easy, generic and cluster safe way to implement that
(except via the contribution mentioned above)
JavaScript aggregation can be inefficient across multiple pages with
different JS requirements
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Key: TAP5-769
URL: https://issues.apache.org/jira/browse/TAP5-769
Project: Tapestry 5
Issue Type: Bug
Components: tapestry-core
Affects Versions: 5.1.0.5
Reporter: Andy Blower
Attachments: 0002-TAP-769.patch, 0003-TAP-769.patch,
0004-TAP-769.patch
I think Tapestry's JavaScript combination functionality is flawed. Each page
component specifies which JS files it needs, which means that JS can be
split into functional units (good for development maintenance) and only the
JS that's actually needed for that page is added for the client to download.
The consequence of this is that pages can have lots of JS files to download,
all of which has to be downloaded before the page is loaded/rendered now that
the script link tags are enforced to be back in the head section. Our search
results page has 34 JS files for instance.
Yahoo's YSlow tool recommends that these files are combined and minified, and
Tapestry includes functionality to do the first (minifying is on the TODO
list I believe) probably as a response to this recommendation which is good.
Unfortunately the implementation based on only having the JS files required
for a page means that the combined JS can easily be unique for most pages of
a site. This means that the client browser has to download cache lots of
large JS multiple times (prototype, scriptaculous, tapestry etc) as part of
bigger combined files, which I think is probably worse than requesting them
separately, but only downloading stuff once and using that for all pages.
To solve this issue, Tapestry script combination could combine all of the
scripts needed for the site, and not just the unique set for each page. That
way only a single JS file needs to be downloaded and cached by the client
browser. I'm aware that this may not be that easy given the existing way only
scripts needed for the page are put on it, so an alternative solution that
may be easier to implement would be to combine scripts into two files for
each page. The first file would contain all of the commonly Tapestry provided
JS such as prototype.js, scriptaculous.js, effects.js, tapestry.js, etc in
one file that's the same for every page, and have the rest in a second file
that is unique for the page but that is not likely to include very large JS
files, just many little ones.
A second flaw that the combination has is that if an external JS file is
requested, script combination is aborted rather than just excluding the
external file from the combination.
One other thing that surprised me about Tapestry's script combination is the
length of the generated filename, for example it's 919 characters long for a
page on our site.
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