Will it play in App Engine - Google App Engine for Java

For information on a particular framework, language, or library, please search for its name on this page. If the item you are interested is not listed, has incorrect information, or you have a fix for a reported issue, please add a comment to the page.

Java Enterprise Edition (Java EE) Technologies

Supported

While we do not support the entirety of the Java EE specification, many of its individual components are supported. These include:

Java Data Objects (JDO) -- notes
Java Persistence API (JPA) -- notes *
Java Server Faces (JSF) 1.1 - 2.0 **
Java Server Pages (JSP) + JSTL ***
Java Servlet API 2.4 -- notes
JavaBeans™ Activation Framework (JAF)
JavaMail -- notes
XML processing APIs including DOM, SAX, and XSLT

* For a guide on "converting" between JPA and JDO, see the blog entry at http://objectuser.wordpress.com/2009/07/04/17-minute-jdo/.

** JSF 1.1 appears to be working out-of-the-box. JSF 1.2 and JSF 2.0 should also work if you set the com.sun.faces.enableMultiThreadedStartup context parameter to false to your web.xml file. Setting this parameter to false (it's set to true by default) will prevent additional threads from being spawned. For more information on running JSF 2.0 in App Engine, see this Site.

*** JSP session beans are not supported; to enable EL parsing, add <%@page isElIgnored="false" %> to your JSPs and <%@tag isElIgnored="false" %> to your tag files.

Not supported

There are various APIs and technologies that are not supported by App Engine at present for various reasons. These include:

Enterprise Java Beans (EJB)
JAX-RPC
JAX-WS
JAXB
Java Database Connectivity (JDBC) **
Java EE™ Connector Architecture (JCA)
Java Management Extensions (JMX)
Java Message Service (JMS)
Java Naming and Directory Interface (JNDI)
Remote Method Invocation (RMI)

** App Engine's underlying datastore is based on BigTable, not a traditional SQL-based RDBMS like MySQL or PostgreSQL. You may either use the low-level datastore API or the JDO or JPA object-relational mapping interfaces provided. Various JDBC wrappers are available for the datastore, and you may still be able to connect to in-memory databases such as the H2 database engine or HSQLDB.

JVM-based Languages

NOTE: All JVM-based languages are subject to the same App Engine sandbox restrictions as Java.

BeanShell
Version(s): ?
Status: COMPATIBLE

CAL
Version(s): ?
Status: COMPATIBLE

CAL, together with the Open Quark framework, can be run on App Engine. More details at http://www.kablambda.org/blog/2009/04/09/functional-programming-on-google-appengine/.

Groovy
Versions: 1.6.1 +
Status: COMPATIBLE

More information is available on the Spring Source blog.

JRuby (Ruby)
Versions: 1.3.1+
Status: COMPATIBLE (see notes)

The latest instructions for rails are at http://rails-primer.appspot.com/.
Ola Bini has posted a series of steps along with his impressions to his blog.
A proof-of-concept sinatra app using JRuby has been posted by Samuel Goebert at http://blog.bigcurl.de/2009/04/running-sinatra-apps-on-google.html. For more on Sinatra, see http://code.google.com/p/appengine-jruby/wiki/GettingStarted.

Jython (Python)
Versions: 2.2, 2.5rc4 +
Status: COMPATIBLE

Modjy, used to bridge Jython WSGI applications to those running inside Java servlet containers, is also compatible with App Engine. See http://opensource.xhaus.com/projects/modjy/wiki/ModjyGoogleAppEngine for a quick tutorial.

Quercus (PHP)
Version(s): ?
Status: COMPATIBLE

See http://brian.brispace.net/2009/04/09/php-on-google-app-engine/#post-398 for an example of how to configure your deployment descriptor to work with Quercus.

Rhino (JavaScript)
Version(s): ?
Status: COMPATIBLE

For a quick tutorial demonstrating how to run Rhino and Helma NG on App Engine, see http://dev.helma.org/ng/Running+Rhino+and+Helma+NG+on+Google+App+Engine/.
Jack, a implementation of the JSGI spec with Rhino support, also works with App Engine. A servlet is available.

Scala
Version(s): ?
Status: COMPATIBLE

Scala works out-of-the-box as does the Lift Web Framework for Scala.
Scala Actors do not work, because they are implemented using threads, which are not supported.
Dave Briccetti has posted his experience running Scala with App Engine to his blog.

Miscellaneous Java™ Libraries and Frameworks

Apache Commons FileUpload
Version: 1.2.1
Status: SEMI-COMPATIBLE

The streaming API added in version 1.2.1 works out of the box.
The traditional API is not supported due to dependencies on java.io.File (App Engine does not expose a writable file system), although a custom FileItemFactory implementation that does not rely on writing files should work.

Apache HttpClient
Version: 4
Status: COMPATIBLE

Requires a custom ConnectionManager that wraps UrlFetch. Details are here and here.

Apache POI
Version(s): ?
Status: INCOMPATIBLE

Apache POI relies on several classes not in the JRE class whitelist including java.awt.Color. A bug has been filed at https://issues.apache.org/bugzilla/show_bug.cgi?id=47497.

Base64 (link)
Version(s): ?
Status: COMPATIBLE

BlazeDS
Version: 3.2.0.3978
Status: COMPATIBLE

To workaround an EMFException thrown by flex.messaging.io.amf.AbstractAmfInput, follow Martin Zoldano's workarounds at http://martinzoldano.blogspot.com/2009/04/appengine-adobe-blazeds-fix.html.
You will need to enable sessions to get BlazeDS working.

Compass
Version(s): ?
Status: SEMI-COMPATIBLE

Shay Banon has posted a screencast at http://www.kimchy.org/searchable-google-appengine-with-compass/ which shows the basic configuration changes needed to enable full text search of datastore entities.
To workaround issues with Compass and JPA persistence, see http://forum.compass-project.org/thread.jspa?threadID=216243&tstart=0.

Direct Web Remoting (DWR)
Version(s): 2.0.5, 3.0 RC1
Status: COMPATIBLE

dyuproject (OpenID RelyingParty 2.0 implementation, OAuth consumer and service provider, JSON IOC, lightweight Servlet-based REST framework)
Version(s): ?
Status: COMPATIBLE

Ehcache
Version: 1.6.0
Status: COMPATIBLE

All features work aside from the DiskStore and replication, but workarounds are available. See http://ehcache.sourceforge.net/documentation/googleappengine.html for more.

Facelets
Version: 1.1.14
Status: COMPATIBLE

Force.com Web Service Connector (sfdc-wsc)
Version(s): ?
Status: COMPATIBLE

A pre-built JAR of the App Engine-compatible sfdc-wsc library is available for download at http://code.google.com/p/sfdc-wsc/downloads/list.

Google Data (GData) client library for Java
Version(s): all
Status: COMPATIBLE

As per this FAQ, you need set a specific configuration error to avoid a runtime permissions error. Otherwise, you will see java.security.AccessControlException: access denied (java.net.NetPermission getCookieHandler) when you try to use the library.

Google Web Toolkit (GWT)
Versions: All
Status: COMPATIBLE

The Google Plugin for Eclipse enhances GWT and App Engine cross-development.

Grails
Version: 1.1.1
Status: SEMI-COMPATIBLE

A plugin has been made available which integrates the App Engine SDK with Grails, adding features to upload Grails application automatically and run the local dev server. To download this plugin or see a screencast and tutorial, see http://grails.org/plugin/app-engine.
As of now, you have to use the "grails app-engine run" command rather than "grails run-app", which blocks other plugins that extend run-app including the GWT plugin. More incompatibilities noted in this thread.

GraniteDS
Version(s): ?
Status: COMPATIBLE

Guice
Version(s): ?
Status: SEMI-COMPATIBLE
Notes:

Guice should work if you build it from trunk.
You may have to add a try-catch block to Finalizer.java to prevent a SecurityException from being thrown. More details at http://groups.google.com/group/google-guice/browse_thread/thread/13a63dc40684abe8.

Hibernate
Versions: All
Status: INCOMPATIBLE

You cannot currently use Hibernate directly. The differences between the App Engine datastore and SQL were too great to get the standard Hibernate up and running under App Engine. App Engine does support JDO and JPA, so you may be able to convert your Hibernate code to use one of these ORM interfaces.

ICEfaces
Version(s): 1.8.1
Status: INCOMPATIBLE

iText
Version(s): ?
Status: INCOMPATIBLE

iText relies on several classes not in the JRE class whitelist including java.awt.Color and java.nio.MappedByteBuffer. A bug has been filed at http://sourceforge.net/tracker/?func=detail&atid=365255&aid=2810312&group_id=15255.

ItsNat (http://www.itsnat.org)
Version: 0.7
Status: SEMI-COMPATIBLE

It works including AJAX: http://itsnatfeatshow.appspot.com/servlet?itsnat_doc_name=manual.core.example
Core level works but Comet (undefined thread retention is prohibited in GAE and sometimes a new thread is needed). Use timers (polling).
Most of components do not work because most of them use Swing classes (and some AWT class), these classes are not allowed in GAE.
More info: http://code.google.com/p/googleappengine/issues/detail?id=1313

Java Topology Suite (JTS)
Version(s): 1.10
Status: COMPATIBLE

A JTS + Restlet demo is available at http://iqbalyusuf.wordpress.com/java-topology-suite-google-app-engine-restlet-test/.
A JTS + GWT + Google Maps demo is available at http://giscloud.appspot.com.

JBoss Seam
Version(s): ?
Status: SEMI-COMPATIBLE

See http://ctpjava.blogspot.com/2009/04/jboss-seam-on-google-app-engine-first.html for a list of modifications that need to be made in order to get JBoss Seam working in App Engine's sandbox.

Jena Semantic Framework
Version(s): ?
Status: SEMI-COMPATIBLE

Jena Semantic Framework does not run in App Engine's production environment out-of-the-box since it relies on the restricted java.rmi.server package, but you can make some modifications to its source to get it working. The solutions are detailed at the bottom of http://groups.google.com/group/google-appengine-java/browse_thread/thread/c2c0d27a7ed42562.

Jersey
Version: 1.0.2
Status: SEMI-COMPATIBLE

Jersey does not run in App Engine's production environment out-of-the-box, but you can make some modifications to get basic uses working. Several of these are documented at http://lqd.hybird.org/journal/?p=123.

log4j
Version(s): ?
Status: COMPATIBLE

MyFaces
Version: 1.1.6
Status: COMPATIBLE

OpenSocial client library for Java
Version(s): 20090402
Status: COMPATIBLE

OSGi
Version(s): ?
Status: SEMI-COMPATIBLE

At least one developer has managed to get OSGi working locally using the Equinox servlet bridge. Details at http://eclipsesource.com/blogs/2009/04/10/osgi-on-appengine/.
An open source port of Felix OSGi called Lemmon is available and has been successfully run on App Engine for Java. See http://lemmon.googlecode.com/.

PDFJet

Version(s): ?
Status: COMPATIBLE

Requires some tweaks to method definitions in several classes (e.g. Image.java, JPGImage.java) to use InputStream instead of File, and remove an AWT dependency in PixelGrabber.java. See http://groups.google.com/group/google-appengine-java/browse_thread/thread/a06dd822a6cee160 for more.

Restlet
Version(s): 2.0 M5 +
Status: COMPATIBLE

The team has created an adaptation of Restlet just for App Engine.
See http://wiki.restlet.org/developers/172-restlet/251-restlet.html for instructions on tuning a standard installation of Restlet for App Engine.
Here's another blog post from the team about Restlet: http://blog.noelios.com/2009/04/11/restlet-in-the-cloud-with-google-app-engine/

RichFaces
Version: 3.1.6
Status: INCOMPATIBLE

RichFaces depends on the javax.imageio package which is presently not listed on the JRE class whitelist.

SiteMesh
Versions: 2.4.2 +
Status: COMPATIBLE

Beginning with version 2.4.2, SiteMesh contains some fixes to allow it to work more smoothly on App Engine, as indicated on its blog.
To use older versions of SiteMesh you may need to make modifications to the com.opensymphony.module.sitemesh.Factory.getEnvEntry method and build the JAR file for the library. For more details, see http://groups.google.com/group/google-appengine-java/browse_thread/thread/1e3868a6a2661585.

Spring MVC
Version: 2.5.6
Status: COMPATIBLE

To see Spring's MVC framework running on App Engine, check out the autoshoppe sample application.
If you're using Spring forms (e.g. using the spring-form.tld tag library and subclassing SimpleFormController), you will need to register custom editors for your properties. This is covered in http://groups.google.com/group/google-appengine-java/browse_thread/thread/d93fd7385bf85bf7.

Spring ORM
Version: 2.5.6
Status: COMPATIBLE

To get Spring working with the App Engine-provided JPA interface, follow the instructions at http://objectuser.wordpress.com/2009/05/19/spring-jpa-in-google-app-engine/, which discusses a workaround to the dependency on javax.naming needed for @PersistenceContext. A more complex workaround is available at http://groups.google.com/group/google-appengine-java/browse_thread/thread/187d41712ec1d394.

Spring Security
Version(s): ?
Status: SEMI-COMPATIBLE

To work around a ClassNotFoundException, you can use a re-compiled version of the library which adds a StringInsensitiveComparator class -- the download is provided at http://www.google-app-engine.com/blog/post/Spring-security-fix-for-google-app-engine.aspx.
See http://www.dotnetguru2.org/bmarchesson/index.php?p=1100 for tips on how to get Spring Security running with App Engine and GWT (in French).
See http://groups.google.com/group/google-appengine-java/browse_thread/thread/964e7f5e42840d9c for discussion on the integration.

Stripes Framework
Version(s): ?
Status: COMPATIBLE

The default multipartwrapper implementation needs a temporary directory on the local file system for file uploads, which App Engine doesn't allow. The workaround is to create your own implementation -- more details at http://groups.google.com/group/google-appengine-java/browse_thread/thread/81dbcf7cf2281014.

Struts 1
Version: 1.2.28
Status: COMPATIBLE

Struts 2
Version(s): ?
Status: COMPATIBLE (see notes)

Struts will not initially work because the OGNL permissions which the framework relies on can't be set due to security restrictions in App Engine's sandbox. However, some users have documented a workaround at http://groups.google.com/group/google-appengine-java/browse_thread/thread/19018b0317f27817.
A tutorial is available at http://whyjava.wordpress.com/2009/08/30/creating-struts2-application-on-google-app-engine-gae/.
A tutorial on uploading files using Struts running on App Engine is available at http://whyjava.wordpress.com/2009/10/04/file-upload-on-google-app-engine-using-struts2/.
Will need to set devMode to false in struts.xml: <constant name="struts.devMode" value="false" />
A group post detailing this is here: http://groups.google.com/group/google-appengine-java/browse_thread/thread/b78fea68441eaf4e/4eec677cef795e03

Tapestry
Version: 5.0.18
Status: COMPATIBLE

Version: 5.1
Status: INCOMPATIBLE

Version 5.1 appears to rely on the Woodstox XML processor, which in turn relies on javax.xml.stream.XMLInputFactory, which isn't on the current JRE class white list. No workarounds are known at this time.

Tiles
Version: 2.0.7
Status: COMPATIBLE

Older versions may not work.

Vaadin
Version(s): ?
Status: COMPATIBLE

Vaadin-based applications can be deployed to App Engine. For more, see http://vaadin.com/wiki/-/wiki/Main/Google%20AppEngine%20HOWTO.

VRaptor 2
Version(s): ?
Status: COMPATIBLE

Requires App Engine sessions to be enabled.

WebORB
Version(s): ?
Status: COMPATIBLE

A patch was made available shortly after launch to make WebORB compatible with App Engine. The patch is available at http://www.themidnightcoders.com/blog/2009/04/running-weborb-for-java-in-google-app.html.

Wicket
Version(s): ?
Status: SEMI-COMPATIBLE

With a couple of quick workarounds, Dan Walmsley has deployed a basic app that uses Wicket. His write-up is located at http://www.danwalmsley.com/2009/04/08/apache-wicket-on-google-app-engine-for-java/.
Nick Wiedenbrueck has also published a write-up showing how to get a simple Wicket application running on App Engine, located at http://stronglytypedblog.blogspot.com/2009/04/wicket-on-google-app-engine.html.

Version(s): 3.6.2 +
Status: COMPATIBLE

Ajax + Mobile Java framework
A how-to on configuring a ZK-based application to work with App Engine is available at http://docs.zkoss.org/wiki/ZK/How-Tos/Installation/How_to_Integrate_ZK_with_Google_App_Engine.

Version:

Will it play in App Engine	Nov 19
jython-r5996-patched-for-appengine.jar	Apr 6
jython-r5996-appengine.patch	Apr 6
appengine.png	Apr 1