I'm trying to get a multi-module Google App Engine project to build with Maven. I have two modules and everything builds fine. But I get the stack trace below when I go into the admin console to look at the modules (i.e. by going to http://localhost:8080/_ah/admin/modules while running mvn appengine:devserver):
[INFO] WARNING: /_ah/admin/modules
[INFO] java.lang.NullPointerException: null value in entry: version=null
[INFO] at com.google.appengine.repackaged.com.google.common.collect.CollectPreconditions.checkEntryNotNull(CollectPreconditions.java:33)
[INFO] at com.google.appengine.repackaged.com.google.common.collect.ImmutableMapEntry.<init>(ImmutableMapEntry.java:47)
[INFO] at com.google.appengine.repackaged.com.google.common.collect.ImmutableMapEntry$TerminalEntry.<init>(ImmutableMapEntry.java:67)
[INFO] at com.google.appengine.repackaged.com.google.common.collect.ImmutableMap.entryOf(ImmutableMap.java:134)
[INFO] at com.google.appengine.repackaged.com.google.common.collect.ImmutableMap$Builder.put(ImmutableMap.java:204)
[INFO] at com.google.apphosting.utils.servlet.ModulesServlet$1.apply(ModulesServlet.java:80)
[INFO] at com.google.apphosting.utils.servlet.ModulesServlet$1.apply(ModulesServlet.java:72)
[INFO] at com.google.appengine.repackaged.com.google.common.collect.Iterators$9.transform(Iterators.java:841)
[INFO] at com.google.appengine.repackaged.com.google.common.collect.TransformedIterator.next(TransformedIterator.java:48)
[INFO] at com.google.appengine.repackaged.com.google.common.collect.ImmutableList.copyOf(ImmutableList.java:271)
[INFO] at com.google.appengine.repackaged.com.google.common.collect.ImmutableList.copyOf(ImmutableList.java:228)
[INFO] at com.google.apphosting.utils.servlet.ModulesServlet.doGet(ModulesServlet.java:92)
[INFO] at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
[INFO] at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
[INFO] at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
[INFO] at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
[INFO] at com.google.appengine.api.socket.dev.DevSocketFilter.doFilter(DevSocketFilter.java:74)
[INFO] at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
[INFO] at com.google.appengine.tools.development.ResponseRewriterFilter.doFilter(ResponseRewriterFilter.java:127)
[INFO] at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
[INFO] at com.google.appengine.tools.development.HeaderVerificationFilter.doFilter(HeaderVerificationFilter.java:34)
[INFO] at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
[INFO] at com.google.appengine.api.blobstore.dev.ServeBlobFilter.doFilter(ServeBlobFilter.java:63)
[INFO] at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
[INFO] at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43)
[INFO] at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
[INFO] at com.google.appengine.tools.development.StaticFileFilter.doFilter(StaticFileFilter.java:125)
[INFO] at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
[INFO] at com.google.appengine.tools.development.DevAppServerModulesFilter.doDirectRequest(DevAppServerModulesFilter.java:366)
[INFO] at com.google.appengine.tools.development.DevAppServerModulesFilter.doDirectModuleRequest(DevAppServerModulesFilter.java:349)
[INFO] at com.google.appengine.tools.development.DevAppServerModulesFilter.doFilter(DevAppServerModulesFilter.java:116)
[INFO] at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
[INFO] at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
[INFO] at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
[INFO] at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
[INFO] at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
[INFO] at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
[INFO] at com.google.appengine.tools.development.DevAppEngineWebAppContext.handle(DevAppEngineWebAppContext.java:98)
[INFO] at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
[INFO] at com.google.appengine.tools.development.JettyContainerService$ApiProxyHandler.handle(JettyContainerService.java:491)
[INFO] at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
[INFO] at org.mortbay.jetty.Server.handle(Server.java:326)
[INFO] at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
[INFO] at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923)
[INFO] at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:547)
[INFO] at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:212)
[INFO] at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
[INFO] at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:409)
[INFO] at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)
[INFO]
To construct my project, this is what I've done so-far:
This results in a single module (default module) with a pom.xml that looks like this:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<packaging>war</packaging>
<version>1.0-SNAPSHOT</version>
<groupId>mynetbaseapiapp</groupId>
<artifactId>mynetbaseapiapp</artifactId>
<properties>
<appengine.app.version>1</appengine.app.version>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<prerequisites>
<maven>3.1.0</maven>
</prerequisites>
<dependencies>
<!-- Compile/runtime dependencies -->
<dependency>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-api-1.0-sdk</artifactId>
<version>1.9.14</version>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.5</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>jstl</groupId>
<artifactId>jstl</artifactId>
<version>1.2</version>
</dependency>
<!-- Test Dependencies -->
<dependency>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-testing</artifactId>
<version>1.9.14</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-api-stubs</artifactId>
<version>1.9.14</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<!-- for hot reload of the web application-->
<outputDirectory>${project.build.directory}/${project.build.finalName}/WEB-INF/classes</outputDirectory>
<plugins>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>versions-maven-plugin</artifactId>
<version>2.1</version>
<executions>
<execution>
<phase>compile</phase>
<goals>
<goal>display-dependency-updates</goal>
<goal>display-plugin-updates</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<version>3.1</version>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.7</source>
<target>1.7</target>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
<version>2.4</version>
<configuration>
<archiveClasses>true</archiveClasses>
<webResources>
<!-- in order to interpolate version from pom into appengine-web.xml -->
<resource>
<directory>${basedir}/src/main/webapp/WEB-INF</directory>
<filtering>true</filtering>
<targetPath>WEB-INF</targetPath>
</resource>
</webResources>
</configuration>
</plugin>
<plugin>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-maven-plugin</artifactId>
<version>1.9.14</version>
<configuration>
<enableJarClasses>false</enableJarClasses>
<!-- Comment in the below snippet to bind to all IPs instead of just localhost -->
<!-- address>0.0.0.0</address>
<port>8080</port -->
<!-- Comment in the below snippet to enable local debugging with a remove debugger
like those included with Eclipse or IntelliJ -->
<!-- jvmFlags>
<jvmFlag>-agentlib:jdwp=transport=dt_socket,address=8000,server=y,suspend=n</jvmFlag>
</jvmFlags -->
</configuration>
</plugin>
</plugins>
</build>
</project>
Converted to EAR Project Layout with Multiple Modules:
mkdir mynetbaseapiapp-frontend
mkdir mynetbaseapiapp-backend
cp -R src mynetbaseapiapp-frontend/
cp -R src mynetbaseapiapp-backend/
rm -rf src
mkdir mynetbaseapiapp-ear
Configured Maven pom.xml files by modeling them closely after a project with a similar 2-module structure at https://github.com/GoogleCloudPlatform/appengine-modules-sample-java.
Manually configured the following files by following https://cloud.google.com/appengine/docs/java/modules/#Java_Configuration:
application.xml - I had to create this from scratch because the Maven archetype didn't provide it
appengine-application.xml - Again, I had to create this manually
appengine-web.xml - I didn't have to create this, I got it for from the Maven archetype:
mynetbaseapiapp ${appengine.app.version} mynetbaseapiapp-frontend
true<system-properties> <property name="java.util.logging.config.file" value="WEB-INF/logging.properties"/> </system-properties>
What I notice is the line <version>${appengine.app.version}</version> is not getting the ${appengine.app.version} variable interpolated by Maven. The interpolation happens in the original project generated by the archetype. But it doesn't work in my multi-module configuration.
Where have I gone wrong?
