Daniel,
I do try to watch out for T5/GAE related posts on this list and try to
respond to the best of my ability. I would blog about this more if I weren't
as swamped with things to do.
I would be interested in hearing from other folks (e.g. Dmitry) that have
deployed on GAE - in previous questions relating to this issue, folks had
mentioned that they don't have a problem w/ this, which makes me think that
I might have something configured incorrectly (although I'm not doing
special here, other than having a few images loaded from the stylesheet). I
do use the AssetAuthorizer (that was eventually added to 5.2) and that's
another possible failure point (e.g. if for whatever reason, the
authorization fails in some cases and denies access).
On the other hand, serving these assets as static content has dropped my
CPU usage - I had an cron job watching the site and keeping it warm (so that
GAE doesn't swap it out), which was using up about 40% of the free CPU quota
- so far, the CPU usage should be about 20% lower.
Regards,
Alex Kotchnev
On Tue, Apr 13, 2010 at 3:44 AM, Daniel Henze <dhe...@googlemail.com> wrote:
> Hi Alex,
>
> thanks for that follow-up post. Since I'm going to develop with T5 on GAE
> as well, this will be in the back of my head as a potential cave-at. I'll be
> interested in any further findings regarding GAE since it seems that
> Tapestry is better tailored towards this particular platform (compared to
> Wicket).
>
> Best regards
> Daniel
>
> Am 13.04.2010 06:23, schrieb Alex Kotchnev:
>
> I spent some more time looking at this and I ended up removing the usage
>> of
>> the ${asset:context:css/foobar.css} from the main templates. After doing
>> so,
>> all of the issues related to the stylesheet (and the sub-stylesheets and
>> images that it loads) were cleared up - now, the stylesheets load properly
>> every time when they're not loaded through the asset service.
>>
>> I first thought that this might be an issue w/ how GAE handles static
>> files
>> - supposedly, all files in the web context are handled specially ( w/ the
>> exception of JSPs of course, but that's not relevant in T5), probably
>> served
>> up from outside of Jetty (which is what runs the app in GAE) and there
>> might
>> be something that is weird in GAE giving access to those static assets.
>> However, after I switched to just using the raw path to the css (w/o using
>> the asset:context binding prefixes), I continued having the same
>> intermittent access issues for assets that are served from a component.
>> Which on its own indicates that the issue is somewhere between the Asset
>> service (which I haven't looked at the source code for yet) and the way it
>> uses the servlet API and/or the filesystem to serve the assets that it's
>> asked for.
>>
>> I haven't moved all my css / image serving out of the asset service - it
>> has
>> some cool ideas in terms of being able to package the app. However,
>> considering that I'm dealing w/ a fairly simple app, and despite that I
>> like
>> the ideas behind the asset service, I'll probably move off of it - I do
>> recall seeing some mentions of an alternative binding prefix to serve the
>> assets in question from a CDN ; however, considering that the google
>> static
>> file serving infrastructure is probably as good as serving from a CDN,
>> I'll
>> probably just stick to static files.
>>
>> Anyway, I thought this might be useful to someone else that might run into
>> issues with the Asset service and GAE. It would be interesting to look at
>> the asset service implementation and see if there is an issue to be filed
>> w/
>> GAE re: accessing resources (classpath and web context).
>>
>> Regards,
>>
>> Alex K
>>
>> On Mon, Apr 12, 2010 at 1:27 PM, akochnev_chub<akoch...@commercehub.com
>> >wrote:
>>
>>
>>
>>> I've been running into some issues w/ the asset service, in that at times
>>> it
>>> responds to service requests with 404s. After "warming up" the app by
>>> reloading the pages in question a few times, the asset service eventually
>>> responds w/ the assets. However, this results in a very unreliable
>>> rendering
>>> of the pages - at times (if the app happens to be "warm"), the pages
>>> render
>>> just fine; at other times, I have to reload them a few times before
>>> getting
>>> to proper rendering. Below are some more details on the issue, any
>>> suggestions on how to deal w/ it would be highly appreciated.
>>>
>>>
>>> There is a pretty good chance that this might be an issue w/ the
>>> underlying
>>> platform (GAE), and the way it chooses to swap the application in and
>>> out;
>>> however, if that were the case, I would have expected more of the
>>> requests
>>> to fail instead of the page content rendering fine and then the assets
>>> not
>>> returning in time.
>>>
>>> I think the issue is partially aggravated by the fact that I load the
>>> main
>>> stylesheet as a context asset (asset:context:/css/foo.css or something
>>> similar), instead of just using the "naked" (e.g. /css/foo.css w/o a
>>> context: prefix) path to the css in the layout; as a result, all of the
>>> "other" css (using yaml for layout) and the images referenced by the main
>>> css depend on the asset service (e.g.
>>>
>>>
>>> http://zadachite-dev.appspot.com/assets/ctx/91328db67ddf7725/images/layout_v2/footer.jpg
>>> )
>>> instead of just being loaded as static files. I was thinking that
>>> switching
>>> the reference to the main stylesheet to not be a context: reference and
>>> marking the web app context resources as static (in the GAE web config
>>> file)
>>> might resolve the issue.
>>>
>>> So, here's an example :
>>> 1. go to http://zadachite-dev.appspot.com (this is the "dev" version
>>> which
>>> is unlikely to be warm right now)
>>>
>>> 2. Upon the initial loading of the pages, some of the graphics (more or
>>> less
>>> randomly) or stylesheets don't return as they get 404s:
>>>
>>> <html><head>
>>> <meta http-equiv="content-type" content="text/html;charset=utf-8">
>>> <title>404 Unable to locate asset
>>> 'classpath:ctx/91328db67ddf7725/yaml/core/base.css' (the file does not
>>> exist).</title>
>>> </head>
>>> <body text=#000000 bgcolor=#ffffff>
>>> <h1>Error: Unable to locate asset
>>> 'classpath:ctx/91328db67ddf7725/yaml/core/base.css' (the file does not
>>> exist).</h1>
>>> </body></html>
>>>
>>>
>>> or for images, it's a straight 404 w/o any further response.
>>>
>>> 3. Browse to some of the other pages of the site - one by one, the
>>> "missing"
>>> assets start showing up one by one and eventually the layout renders
>>> correctly. After the app is "warmed up" now, even if you refresh the page
>>> including the initially cached assets, they load fine.
>>> --
>>> View this message in context:
>>>
>>> http://old.nabble.com/Asset-service-issues-in-GAE-tp28219164p28219164.html
>>> Sent from the Tapestry - User mailing list archive at Nabble.com.
>>>
>>>
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>>>
>>>
>>
>>
>
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