Problem updating my project to new SDK

[Paul]

Hi,

I am trying to update to the new SDK in my project settings. I am not
using Eclipse plugin as it does not work. I use maven for running and
deploying. Even though my xml points to newest sdk, it does not work
and shows standard message about older sdk version. When running
locally it uses correct version, but not always. But when deploying it
shows that I'm using 2-3 versions older SDK. Am I missing something?

[Ian Marshall]

I believe that the GAE/J SDK files we have in our

war\WEB-INF\lib

folder dictate to GAE/J which version of the SDK we want to be run in
production. For example: I have

appengine-api-1.0-sdk-1.5.5.jar

amongst other .jar files, so my app will run under the Java 1.5.5 SDK
when deployed in production. (Yes, I haven't upgraded my build
environment to take the newest SDK into account.

Any help? (Hello fellow Apache Wicket developer!)

[Ian Marshall]

I love Wicket. I can use my Java experience (and I really like Java
too). Wicket is my first web development framework, and I love the
clean split between the HTML and Java code (for me, the links between
them are just some wicket tags). I do not do all this servlet and
related stuff; I let Wicket do all that for me!

As for start-up times, what's your data persistence technology? I use
JDO. For this, there is a many-second period required to instantiate a
JVM's singleton instance of a persistence manager factory (PMF). My
ways to cope with this are:
1. Enqueue a task at start-up to instantiate a PMF instance.
2. Ensure that the home page does not need to exchange data with
the datastore.

My start-up times can be very slow for my zero traffic due to a new
JVM being started, but that's nothing to do with Wicket or JDO. I can
always have a JVM instance always on to counter this.

-------- Original Message --------
I will take a look at that, it was quite mysterious to me, as I have
even deleted all old sdks from my disk and changed all reference.

Anyway, are you happy with Apache Wicket? I am quite early with my
project and I really like Wicket. I am a bit worried about performance
though - do you have any issues with that? How about startup times?
Mines are really slow, but I am not sure if Wicket has anything to do
with it.

[André Pankraz]

With Frameworks like Wicket and JSF I would be much more worried about this stateful view trees on server side in the session.
These Frameworks are nice to develop heavy form business apps - but i'm not sure if they are really a good fit for open internet apps.
They have another problem class in view than the GAE.

I'm not sure if the usage of such complex (not bad) Frameworks above the GAE abstraction layers will not give you more problems than productivity gains.

[Paul]

I use JDO too, I have built my app on top of that maven archetype with
JDO and Wicket. With Guice too.

I really like same things you mentioned and I am still constantly
surprised that people prefer JSP and JSF. I have to work on Oracle's
ADF at my day job, really ugly stuff.

My home page does not exchange data with datastore, at least not
initially [it has login screen]. Could you tell me more about point
1?

[Paul]

Hmm... I still can't get it to work. I have all references to 1.6.1, I
have deleted everything that could include anything connected to old
SDK and all old SDKs and still the same.

maven gae:version gives that:

[INFO] SDK directory: C:\Users\Zeldor\.m2\repository/com/google/
appengine/appengine-java-sdk/1.6.1/appengine-java-sdk-1.6.1
[INFO] SDK version:
Release: 1.5.2
Timestamp: Tue Jul 19 01:48:56 CEST 2011
API versions: [1.0]

Any ideas? In my pom.xml I have:

<properties>
<!--
This is the App Engine SDK version. It's used by the maven-
gae-plugin.
See http://code.google.com/p/maven-gae-plugin/ for
additional configuration options.
-->
<gae.version>1.6.1</gae.version>

[Ian Marshall]

Hi Paul,

I am not a Maven person; I still use Ant with my NetBeans IDE. So I
probably cannot help you. Hopefully someone else on this forum can.

(As a non-Maven person, does your Maven build a war folder prior to
running your GAE/J development server? If so, you could take a peek in
the folder I mentioned earlier to see which SDK .jar files get put in
there.)

(I'll answer your other question next week when I next open my IDE.)

Ian

[Ian Marshall]

Hi Paul,

Enqueuing a task at start-up to instantiate a PMF instance
----------------------------------------------------------

First, some code.

  private static String g_sDatabaseMode = null;
  private static final Object objLockPMF = new Object();
  private static volatile PersistenceManagerFactory g_pmf = null;

  /**
   * If this class's static singleton <code>PersistenceManagerFactory</code>
   * is <code>null</code>, then construct it in a synchronised block of code.
   * @return
   *   This class's static singleton <code>PersistenceManagerFactory</code>.
   */
  public static PersistenceManagerFactory getPersistenceManagerFactory()
  {
    if (g_pmf == null)
      synchronized(objLockPMF)
      {
        if (g_pmf == null)
        {
          loadProperties();    // Sets g_sDatabaseMode
          g_pmf = JDOHelper.getPersistenceManagerFactory(g_sDatabaseMode);
        }
      }

    return g_pmf;
  }

On a first hit of my web application's home page, a task is enqueued for immediate execution. This task calls the above method. In effect, I am using a separate "thread" to initialise the WebAplication class's singleton instance of a PersistenceManagerFactory. Since the method

  PersistenceManagerFactory pmf = JDOHelper.getPersistenceManagerFactory(String s);

takes a few seconds to return, my use of an enqueued task means that this delay is not shown to the user. Exception: since all my code to exchange data with the datastore uses the above method, a user's attempt to do something before the above call has returned (from the home page or otherwise) will involve a delay to wait for the call to complete, since my typical datastore data exchange code is like this:

  PersistenceManagerFactory pmf = DataExchange.getPersistenceManagerFactory();
  PersistenceManager pm = pmf.getPersistenceManager();
  Transaction tx = pm.currentTransaction();
  try
  {
    tx.begin();

    //
    // Do data exchange stuff
    //

    tx.commit();
  }
  finally
  {
    try
    {
      if (tx.isActive())    // Because of an exception, say
        tx.rollback();
    }
    finally
    {
      pm.close();
    }
  }

Any help?

Ian



-------- Original Message --------

Subject:	[google-appengine] Re: Problem updating my project to new SDK
Date:	Sat, 17 Dec 2011 06:24:14 -0800 (PST)
From:	Paul <pgronk...@gmail.com>
Reply-To:	google-a...@googlegroups.com
To:	Google App Engine <google-a...@googlegroups.com>

[Paul]

Thanks for sharing it, I will see how I can use it. I use Guice
though, so I am injecting repositories into classes and then just
calling persist. So not sure if that can work be initiated before
somehow.

And it looks like I won't be able to test anything today, I just run
out of free quota, when trying to clean up over 30k _ah_SESSION
entities...