Per #1, the GAE people highly discourage pinging to keep the instance alive. Also, I tried it for a bit anyways, and it didn't help. I get instance restarts in the MIDDLE of page loads (hint hint: I could use help on my other post!). The thing to realize with GAE is that you need to keep everything out of your Application init().
It takes some effort, but you can get pretty good Wicket apps running on GAE. It's certainly a lot harder, though, than running it on your own. Jake marc fawzi wrote: > > Hey guys > > I'm new to Wicket > > I've made two discoveries with respect to GAE and Wicket: > > 1. I figured out how to keep my GAE app instance hot at all times (well, > at > least for 99.9% of the time.. the GAE still produces "transient errors" > every now and then) -- It's really simple: just have a script that > launches > a new task every 12 seconds and set the task url to a url that is routed > to/handled by the script itself then when the script runs again (in this > way) it will do two things: 1) urlfetch a url that is handled by the app > you > wish to keep hot (which is on another *.appspot.com url) and 2) starts > schedule another task in 12 seconds. Infinite task loop. Google does kill > the task loop eventually so then you need a cron job to run every 1 hour > to > restart the script :) and that's it. > > 2. Someone (srfarley) is working on a version of Wicket for GAE: > > "This project provides a template to help you get started with building a > Wicket <http://wicket.apache.org/> application for Google App > Engine<http://code.google.com/appengine/>. > It is a re-implementation of the Guestbook application described by the > App > Engine tutorial > <http://code.google.com/appengine/docs/java/gettingstarted/>. > Whereas the tutorial uses raw servlets and JSP to demonstrate a some of > the > basic features of App Engine, this project uses Wicket as the web > framework. > > > In addition, the project defines classes for handing persistence using > JDO<http://code.google.com/appengine/docs/java/datastore/>, > and uses Google Guice <http://code.google.com/p/google-guice/> to inject > instances of these classes into the Wicket pages for interacting with the > App Engine datastore. > > For unit testing, the project contains base classes that set up the App > Engine development environment so you can write tests against the full > stack, including those that interact directly with the Wicket pages. The > testing framework is TestNG <http://testng.org/doc/index.html>, but it is > possible to convert them to JUnit tests with some work." > > http://code.google.com/p/wicket-gae-template/ > > Given that I've never used Wicket (I looked at a couple examples so far) > I'm > hoping that we can help each other as we attempt to get good outcome for > our > Wicket+GAE implementations .... To make things more challenging, I'm using > Scala, which I've never run on GAE before and I'm also new to it :) > > Is there an IRC channel for Wicket users or is this the best place for > newbies like me to post questions and get help? > > Thanks, > > Marc > > On Tue, Apr 13, 2010 at 6:20 AM, jbrookover <jbrooko...@cast.org> wrote: > >> >> I'm pretty committed to a project using Wicket on GAE. I haven't >> encountered >> any deserialization issues that people have been bringing up, which makes >> me >> worry a bit since I've encountered (and dealt with) a slew of other >> issues >> :) >> >> Regarding the HttpSessionStore, I discovered a bad coding practice of >> mine >> when every single session entry in the datastore was 500KB+. Once I >> resolved that issue, using more transient fields and detachable models, >> I'm >> relatively happy with the results. GAE, by default, uses the MemCache to >> implement this feature so it should be relatively speedy. It's no >> different >> from any other application storing data in the >> javax.servlet.http.HttpSession. >> >> My only lingering problem (another thread here) is that GAE can trash >> your >> application instance at any point. If you are relying on >> SharedResources, >> those can go away - even in the middle of an active page load, >> potentially >> breaking some links. Currently looking for a way around that :) >> >> Jake >> >> >> Richard Nichols-3 wrote: >> > >> > Biggest problem, and IMO a show stopper, is the Serialization issues. >> > >> > Since Wicket serializes session data (pagemap etc) you have to enable >> > the GAE session-store to get wicket working correctly on GAE. >> > >> > GAE clusters sessions by writing them to the GAE data store to spread >> > the session across the cluster - and writes are *slow*. >> > >> > Worse though, if you create an incompatible change to a serialized >> > page/component/model, when that user returns to your application, GAE >> > will quietly fail and the user will get a blank page. Checking the GAE >> > error log reveals a deserialization error in the core GAE engine. >> > >> > This is because the session reserialization in GAE is handled at the >> > GAE/Jetty level and any error in reconsitution of the error currently >> > breaks GAE completely. Google has acknowledged this problem, but for >> > most frameworks it's not a big deal as you don't store large Objects >> > in the HttpSession. >> > >> > I had planned to deploy the site I'm currently working on >> > http://www.onmydoorstep.com.au/ on GAE but after a few weeks of >> > running the prototypes on GAE, I found the performance to be too poor >> > and the infrastructure too flakey for a production site. >> > >> > NB - It's certainly possible to create high-performance/reliable sites >> > using GAE/J, but Wicket is not a suitable framework due to the >> > Serialization data store write problem. >> > >> > Even if the performance were better and the deserialization issue was >> > fixed, you would blow through your data store quota in no-time due to >> > the amount of data store in the session. >> > >> > If anyone has solutions or further experience with these issues - I'm >> > all ears! :) >> > >> > cheers, >> > Rich >> > >> > On 8 April 2010 17:00, Josh Kamau <joshnet2...@gmail.com> wrote: >> >> What are the main issues with wicket and Google app engine >> >> >> > >> > >> > >> > -- >> > Richard Nichols :: http://www.visural.com/ :: >> > http://www.richardnichols.net/ >> > >> > --------------------------------------------------------------------- >> > To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org >> > For additional commands, e-mail: users-h...@wicket.apache.org >> > >> > >> > >> >> -- >> View this message in context: >> http://old.nabble.com/Wicket-And-GAE-tp28174925p28229863.html >> Sent from the Wicket - User mailing list archive at Nabble.com. >> >> >> --------------------------------------------------------------------- >> To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org >> For additional commands, e-mail: users-h...@wicket.apache.org >> >> > > -- View this message in context: http://old.nabble.com/Wicket-And-GAE-tp28174925p28242292.html Sent from the Wicket - User mailing list archive at Nabble.com. --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org For additional commands, e-mail: users-h...@wicket.apache.org
