Connecting Apache and Tomcat using mod_proxy_ajp works but JDBC then fails

Question

I have a working Apache 2.2.16 on Debian Squeeze that serves some PHP applications from /var/www/ using different domains (e.g. phpApp1.com, phpApp2.com).

I also have a working Tomcat 7.x that lives in /opt/tomcat/ and servers a JSF+JPA application that lives in /opt/tomcat/webapps/MyApp/.

So MyApp can be accessed through e.g. myapp.com:8080/MyApp/home.html or phpApp1.com:8080/MyApp/home.html (because of the port). Since I wanted this to be myapp.com/home.html instead, I connected Apache and Tomcat using mod_proxy_ajp using the following config files:

An Apache virtual host in /etc/apache2/sites-available/MyApp

<Virtualhost *:80>
    ServerName myapp.com
    ServerAlias *.myapp.com
    ProxyPass / ajp://localhost:8009/
    ProxyPassReverse / ajp://localhost:8009/
</Virtualhost>

And a Tomcat virtual host in /opt/tomcat/conf/server.xml

<Host name="myapp.com" appBase="webapps" unpackWARs="true" autoDeploy="true">
    <Context path="" reloadable="true" debug="0" docBase="MyApp" />
    <Alias>www.myapp.com</Alias>
</Host>

This works to the point that I cann access http://myapp.com/home.html and get a correct html page including css, images and js. So the AJP connector in tomcat should work.

BUT the app fails to establish a JDBC connection that otherwise works fine. It does not matter whether i use myapp.com or myapp.com:8080, it fails either way. However, it works if I access my app throug http://phpapp1.com:8080/MyApp/home.html. It only fails when I use the proxy-domain "myapp.com".

Has anyone experienced similar problems when using AJP and JDBC? How can I solve this? I had the same problem when using mod_jk, which makes use of AJP, too. Thanks in advance.

Update 1

@Mark Rotteveel: What do you mean by "connecting directly"? I mean the JDBC connection is working if I use one of the domains that are not listed as virtual hosts in tomcats server.xml.

Here is the connection error:

ERROR: HHH000231: Schema export unsuccessful
org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot create JDBC driver of class '' for connect URL 'null'
at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createConnectionFactory(BasicDataSource.java:1452)
at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:1371)
at org.apache.tomcat.dbcp.dbcp.BasicDataSource.getConnection(BasicDataSource.java:1044)
at org.hibernate.service.jdbc.connections.internal.DatasourceConnectionProviderImpl.getConnection(DatasourceConnectionProviderImpl.java:141)
at org.hibernate.tool.hbm2ddl.SuppliedConnectionProviderConnectionHelper.prepare(SuppliedConnectionProviderConnectionHelper.java:51)
at org.hibernate.tool.hbm2ddl.DatabaseExporter.<init>(DatabaseExporter.java:52)
at org.hibernate.tool.hbm2ddl.SchemaExport.execute(SchemaExport.java:367)
at org.hibernate.tool.hbm2ddl.SchemaExport.create(SchemaExport.java:304)
at org.hibernate.tool.hbm2ddl.SchemaExport.create(SchemaExport.java:293)
at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:492)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1744)
at org.hibernate.ejb.EntityManagerFactoryImpl.<init>(EntityManagerFactoryImpl.java:94)
at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:905)
at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:890)
at org.hibernate.ejb.HibernatePersistence.createEntityManagerFactory(HibernatePersistence.java:57)
at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:63)
at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:47)
at com.myapp.util.database.Database.<init>(Database.java:70)
at com.myapp.util.database.Database.<clinit>(Database.java:38)
at com.myapp.controller.file.UploadBacking.ajaxUpload(UploadBacking.java:89)
at com.myapp.controller.file.UploadBacking$Proxy$_$$_WeldClientProxy.ajaxUpload(UploadBacking$Proxy$_$$_WeldClientProxy.java)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.el.parser.AstValue.invoke(AstValue.java:264)
at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:278)
at org.jboss.weld.util.el.ForwardingMethodExpression.invoke(ForwardingMethodExpression.java:39)
at org.jboss.weld.el.WeldMethodExpression.invoke(WeldMethodExpression.java:50)
at org.apache.myfaces.view.facelets.el.ContextAwareTagMethodExpression.invoke(ContextAwareTagMethodExpression.java:96)
at org.apache.myfaces.view.facelets.tag.jsf.core.AjaxHandler$AjaxBehaviorListenerImpl.processAjaxBehavior(AjaxHandler.java:495)
at javax.faces.event.AjaxBehaviorEvent.processListener(AjaxBehaviorEvent.java:57)
at javax.faces.component.behavior.BehaviorBase.broadcast(BehaviorBase.java:74)
at javax.faces.component.UIComponentBase.broadcast(UIComponentBase.java:405)
at javax.faces.component.UICommand.broadcast(UICommand.java:103)
at javax.faces.component.UIViewRoot._broadcastAll(UIViewRoot.java:1028)
at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:286)
at javax.faces.component.UIViewRoot._process(UIViewRoot.java:1375)
at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:752)
at org.apache.myfaces.lifecycle.InvokeApplicationExecutor.execute(InvokeApplicationExecutor.java:38)
at org.apache.myfaces.lifecycle.LifecycleImpl.executePhase(LifecycleImpl.java:170)
at org.apache.myfaces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:117)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:197)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.ocpsoft.rewrite.servlet.RewriteFilter.doFilter(RewriteFilter.java:183)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
at org.apache.coyote.ajp.AjpProcessor.process(AjpProcessor.java:200)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:579)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
Caused by: java.lang.NullPointerException
at sun.jdbc.odbc.JdbcOdbcDriver.getProtocol(JdbcOdbcDriver.java:507)
at sun.jdbc.odbc.JdbcOdbcDriver.knownURL(JdbcOdbcDriver.java:476)
at sun.jdbc.odbc.JdbcOdbcDriver.acceptsURL(JdbcOdbcDriver.java:307)
at java.sql.DriverManager.getDriver(DriverManager.java:253)
at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createConnectionFactory(BasicDataSource.java:1437)
... 60 more

From Database.java:

private Database() {
    entityManagerFactory = Persistence.createEntityManagerFactory("myapp_persistence_unit");
}

MyApp/META-INF/context.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE Context>

<Context>

<Resource
    name="jdbc/db_myapp" 
    auth="Container"
    type="javax.sql.DataSource" 
    username="user_myapp" 
    password="##########"
    driverClassName="com.mysql.jdbc.Driver"
    url="jdbc:mysql://localhost:3306/db_myapp?autoReconnect=true"
    validationQuery="select 1"
    maxActive="15" 
    maxIdle="3" />

<Valve
    className="org.apache.catalina.valves.AccessLogValve"
    directory="logs/myapp"
    prefix="myapp_access_"
    suffix=".log"
    pattern="%h %l %u %t &quot;%r&quot; %s %b"
    resolveHosts="false" />

</Context>

From WEB-INF/web.xml

<resource-ref>
    <description>MySQL database</description>
    <res-ref-name>jdbc/db_myapp</res-ref-name>
    <res-type>javax.sql.DataSource</res-type>
    <res-auth>Container</res-auth>
</resource-ref>

And finally WEB-INF/classes/META-INF/persistence.xml:

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0"
    xmlns="http://java.sun.com/xml/ns/persistence"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/persistence 
    http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">

    <persistence-unit name="myapp_persistence_unit">
        <properties>
            <property name="hibernate.connection.datasource" value="java:comp/env/jdbc/db_myapp" />
            <property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5InnoDBDialect" />
            <property name="hibernate.current_session_context_class" value="thread" />
            <property name="hibernate.show_sql" value="true" />
            <property name="hibernate.format_sql" value="true" />
            <property name="hibernate.hbm2ddl.auto" value="create-drop" />
        </properties>
    </persistence-unit>

</persistence>

Answer 1

I finally got it to work. If you create a virtual host in tomcat, you have to put an exact copy of your applications /META-INF/context.xml into /tomcat/conf/Catalina/domain.com/ and name it context.xml.default. Well, I don't know if this is always the case, but for my setting it was. So these are my current config files that do the job:

/etc/apache2/sites-enabled/domain.com

<Virtualhost *:80>
    ServerName domain.com
    ServerAlias *.domain.com

    ProxyRequests Off
    <Proxy *>
        Order deny,allow
        Allow from all
    </Proxy>
    ProxyPass / ajp://my.server.ip:8009/
</Virtualhost>

/tomcat/conf/server.xml

<Host name="domain.com">
    <Context path="" docBase="MyApp" />
    <Alias>www.domain.com</Alias>
</Host>

I tried this after reading this thread on coderanch.com from 2006 (the authors solution is in the last post). I did not change the web.xml or context.xml since this was not a misconfiguration of the <Resource> element. Anyway, thanks for your attempts to help :)

Answer 2

Make sure you have your mysql-connector-j.x.y.z.jar file in exactly one place: Tomcat's lib directory. Make sure you don't have a stray copy in any of your webapps' WEB-INF/lib directories.

Two unrelated tips:

1. Don't use autoReconnect
2. Use /* ping */ SELECT 1 as your validation query: recent versions of Connector/J will use a lightweight "ping" instead of actually issuing a query in order to test a connection's validity