The issue with the AppEngine enhancer still exists with Windows 7. Let’s hope for the next version of Windows then…

I’m struggling with an issue where Google AppEngine will take over 30 seconds to do the initial loading of my hosted web-application. Now apparently it does take a while to load applications that rely on allot of different jar files. Which mine naturally does.

There are however some rumors on the AppEngine group that they are looking to improve the loading time of the applications. Here is a link to one of the discussions. Now this  is just one, I’ve seen others where similar statements have been made.

Now I’m looking forward to get the speed up on my application. Especially if I don’t have to do much about it. However there are some tips out there, due to my lack of computer at the moment I haven’t tested the recommendations but in the thread called: startup takes forver “stumpy” has a few recommendations to improve the start time for Google AppEngine for Java.

I upgraded this morning, figuring that the changes related to the .gsp views and their pre-compiling would reduce the cold start issues I’m having with Google AppEngine.

However the 1.2-M2 release of Grails, doesn’t fly on Google AppEngine right now. As far as I can see on the mailing list others have had this issue as well.

The problem I’m experiencing is that the LogManager cannot instantiate.

Context initialization failed
org.springframework.beans.factory.access.BootstrapException: Error executing bootstraps; nested exception is org.codehaus.groovy.runtime.InvokerInvocationException: java.lang.NoClassDefFoundError: java.util.logging.LogManager is a restricted class. Please see the Google App Engine developer's guide for more details.
	at org.codehaus.groovy.grails.web.context.GrailsContextLoader.createWebApplicationContext(GrailsContextLoader.java:74)
	at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:197)
	at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:47)
	at org.mortbay.jetty.handler.ContextHandler.startContext(ContextHandler.java:530)

And

Context initialization failed
org.springframework.beans.factory.access.BootstrapException: Error executing bootstraps; nested exception is org.codehaus.groovy.runtime.InvokerInvocationException: java.lang.NoClassDefFoundError: Could not initialize class com.google.apphosting.runtime.security.shared.stub.java.util.logging.LogManager

Update: Chad has created a JIRA for this issue located here:http://jira.codehaus.org/browse/GRAILSPLUGINS-1546

Also here is a link to the discussion on the Grails thread:

http://www.nabble.com/java.util.logging.LogManager-is-a-restricted-class.-Please-see-the–Google-App-Engine-developer%27s-guide-for-more-details.-td25453128.html

I’ve been having this issue for a while. Putting it off, but now I had to get my hands dirty. The findBy… methods weren’t returning any objects even though there were data fitting the specified values.

So tonight I finally took the time to take a look at it. My theory was that I could figure out what was wrong by reading the code in JpaPluginSupport.groovy, located in the GORM-JPA plugin.

Now I didn’t find out why its not working. It even looks like its not supported, but I can’t say for sure. What I did however, was find a workaround.

Instead of doing

User.findByEmail(newSaga.email)

I do

User.findWhere(email: newSaga.email)

Using the findWhere method I get results. This is the workaround I’ll go for for now.

Sending emails with Google AppEngine is quite straight forward once you get a hang of things. I ran into some issues, for example I never got the high level api’s to work. The code executed but the emails were never received. Instead I went for Google AppEngines own “low level” api, it worked much better.

What I did is that I set up a really simple MailService, similar to that which is installed with the Mail plug in. However, I do not handle templates instead I just send strings with the mail message.

package mail

import com.google.appengine.api.mail.MailService
import com.google.appengine.api.mail.MailService.Message
import com.google.appengine.api.mail.MailServiceFactory
import javax.mail.MessagingException
import javax.mail.internet.AddressException

class MailService {

 boolean transactional = true

 def sendMail(subject, msgBody, too) {

 try {
 def service = MailServiceFactory.getMailService();

 def msg = new com.google.appengine.api.mail.MailService.Message();
 msg.setSender("xxx");
 msg.setTo(too);
 msg.setSubject(subject);
 msg.setHtmlBody(msgBody);
 service.send(msg);

 } catch (AddressException e) {
 // ...
 } catch (MessagingException e) {
 // ...
 }

 }
}

As you can see it is quite straight forward. I’d like to mention though that in the above code you see a red xxx. This is where you put your sender address. It needs to either be the email to an admin (registered developer) of the app, or it has to be a user logged in using Google’s own login.

With the low-level api it throws an exception like the one below:

Uncaught exception from servlet
org.codehaus.groovy.runtime.InvokerInvocationException: java.lang.IllegalArgumentException: Unauthorized Sender: Unauthorized sender

Good luck!

I ran into an issue last night where Google AppEngine wouldn’t persist my entities. If I create an entity using the parameters provided by Grails; then the Save operations would fail with the following error

Uncaught exception from servlet
org.codehaus.groovy.runtime.InvokerInvocationException: groovy.lang.MissingMethodException: No signature of method: java.lang.StringBuilder.leftShift() is applicable for argument types: (org.codehaus.groovy.runtime.GStringImpl) values: [(login.email  = ?1 )]
	at com.studentsonly.grails.plugins.uiperformance.CacheFilter.doFilter(CacheFilter.java:71)
	at com.google.apphosting.runtime.jetty.SaveSessionFilter.doFilter(SaveSessionFilter.java:35)
	at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43)
	at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.handle(AppVersionHandlerMap.java:237)
	at com.google.apphosting.runtime.jetty.RpcRequestParser.parseAvailable(RpcRequestParser.java:76)
	at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:139)
	at com.google.apphosting.runtime.JavaRuntime.handleRequest(JavaRuntime.java:235)
	at com.google.apphosting.base.RuntimePb$EvaluationRuntime$6.handleBlockingRequest(RuntimePb.java:4823)
	at com.google.apphosting.base.RuntimePb$EvaluationRuntime$6.handleBlockingRequest(RuntimePb.java:4821)
	at com.google.net.rpc.impl.BlockingApplicationHandler.handleRequest(BlockingApplicationHandler.java:24)
	at com.google.net.rpc.impl.RpcUtil.runRpcInApplication(RpcUtil.java:359)
	at com.google.net.rpc.impl.Server$2.run(Server.java:820)
	...

The issue is described here. I tried their solution and it works fine for me.

I ran into another problem with Google AppEngine. I finally got it to save my entities, only to find it crashing as I wanted to send them back again rendered as JSON.

I had a piece of code looking like this:

def services = {
 params.max = Math.min(params.max ? params.max.toInteger() : 10, 100)
 render Offering.list(params) as JSON;
 }

The code is simple enough, it loads all the Service offerings using GORM and then renders them as JSON using the built in converter. This resulted in the following error:

Uncaught exception from servlet
org.codehaus.groovy.runtime.InvokerInvocationException: org.codehaus.groovy.grails.web.converters.exceptions.ConverterException: Error converting Bean with class org.codehaus.groovy.reflection.ClassLoaderForClassArtifacts
...
Caused by: org.codehaus.groovy.grails.web.converters.exceptions.ConverterException: Error converting Bean with class org.codehaus.groovy.reflection.ClassLoaderForClassArtifacts
	at grails.converters.JSON.value(JSON.java:199)
	at grails.converters.JSON.convertAnother(JSON.java:156)
...
	at com.google.apphosting.runtime.security.shared.intercept.java.lang.reflect.Method_$3.run(Method_.java:149)
	at java.security.AccessController.doPrivileged(Native Method)
	at com.google.apphosting.runtime.security.shared.intercept.java.lang.reflect.Method_.privilegedInvoke(Method_.java:147)
	at com.google.apphosting.runtime.security.shared.intercept.java.lang.reflect.Method_.invoke(Method_.java:120)
	... 26 more
Caused by: java.lang.reflect.InvocationTargetException
	at com.google.apphosting.runtime.security.shared.intercept.java.lang.reflect.Method_$3.run(Method_.java:149)
	at java.security.AccessController.doPrivileged(Native Method)
	at com.google.apphosting.runtime.security.shared.intercept.java.lang.reflect.Method_.privilegedInvoke(Method_.java:147)
	at com.google.apphosting.runtime.security.shared.intercept.java.lang.reflect.Method_.invoke(Method_.java:120)
...
Caused by: java.security.AccessControlException: access denied (java.lang.RuntimePermission getClassLoader)
	at java.security.AccessControlContext.checkPermission(Unknown Source)
	at java.security.AccessController.checkPermission(Unknown Source)
	at java.lang.SecurityManager.checkPermission(Unknown Source)
	at java.lang.ClassLoader.getParent(Unknown Source)
	... 59 more

The problem is that the GORM loads the class with some meta data attached to it. I’m not allowed to reflect over this meta data, so the normal converter fails with the above error. I took the privilege to shorten the stack trace somewhat.

The work around is simple and elegant. I use the groovy collection method called select. With this I can construct a list with maps with the fields I want in my JSON and render them using the normal converter.

def services = {
 params.max = Math.min(params.max ? params.max.toInteger() : 10, 100)
 def list =  Offering.list(params);
 render list.collect { offering->[id:offering.id, name:offering.name]} as JSON
 }

The above code works fine on Google AppEngine.

I hope this helps someone else.