I want the last 2 hours back!

I just spent a few hours writing an Acegi filter to get a certificate from a form post, and put it into a modified User Detail principle. All well and good, except after a redirect back to / I got the error below. Normally this would redirect you back into the application using a JSP page. It turned out that because I’m using Acegi 1.0.5 which has a bug when there is no access denied page handler defined. The reason this occurs only when I was logged in was because I neglected to add ROLE_ANONYMOUS authentication authority list. If only the error meant something debugging wouldn’t have been so hard.

HTTP ERROR: 500

INTERNAL_SERVER_ERROR

RequestURI=/

Caused by:

java.lang.NullPointerException
	at org.acegisecurity.ui.ExceptionTranslationFilter.handleException(ExceptionTranslationFilter.java:229)
	at org.acegisecurity.ui.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:176)
	at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:275)
	at org.acegisecurity.providers.anonymous.AnonymousProcessingFilter.doFilter(AnonymousProcessingFilter.java:125)
	at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:275)
	at org.acegisecurity.ui.AbstractProcessingFilter.doFilter(AbstractProcessingFilter.java:271)
	at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:275)
	at org.acegisecurity.ui.logout.LogoutFilter.doFilter(LogoutFilter.java:110)
	at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:275)
	at org.acegisecurity.context.HttpSessionContextIntegrationFilter.doFilter(HttpSessionContextIntegrationFilter.java:249)
	at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:275)
	at org.acegisecurity.util.FilterChainProxy.doFilter(FilterChainProxy.java:149)
	at org.acegisecurity.util.FilterToBeanProxy.doFilter(FilterToBeanProxy.java:98)
	at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1089)
	at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:365)
	at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
	at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
	at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:712)
	at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:405)
	at org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:211)
	at org.mortbay.jetty.handler.HandlerCollection.handle(HandlerCollection.java:114)
	at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:139)
	at org.mortbay.jetty.Server.handle(Server.java:295)
	at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:503)
	at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:827)
	at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:511)
	at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:210)
	at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:379)
	at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:361)
	at org.mortbay.thread.BoundedThreadPool$PoolThread.run(BoundedThreadPool.java:442)

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Spring and JNDI (Tomcat or Jetty)

Recently I had need to deploy some Spring webapps which required predeploy configuration. Being the first time I had to find a serious answer I looked to the mythical JNDI for an answer. This document is meant to complement other Spring JNDI documents out there.

Essentially the problem is this. We need to deploy a webapp. The webapp needs configurations (database and webservice endpoint locations). Editing properties files or XML config within the webapp isn’t nice, because on a redeploy the config will be lost. Inside containers like Tomcat I am not aware of a way to easily add extra items to the classpath which won’t get nuked unexpectedly, so solutions like PropertyPlaceholderConfigurer don’t really fly as the properties file will end up within the webapp. And I don’t like the idea of setting environment variables for to locate such things.

In steps JNDI. JNDI is the Java answer to namespaced, centralised configuration. Application containers like Tomcat, Jetty, Glassfish, etc all allow you to export objects via JNDI. This may not be a completely correct description, but it is sufficient for this demonstration. The trick is how to use these. I’ll show Jetty configs (which in Maven live in src/main/webapp/WEB-INF/jetty-env.xml) as well as some references to Tomcat (in $CATALINA_HOME/conf/server.xml or better still, in $CATALINA_HOME/conf/Catalina/[engine]/<webapp>.xml) (more on Tomcat here). This means that the config lives OUTSIDE the webapp, and is immune to inadvertant changes, making hot-patching sites easier as War/webapp is independent of the site config.

First, exposing a DB.
This exposes a Postgres DB on the name icatDB. Note, there is a special JDBC namespace. Also note I am not using the normal Postgres connection class, rather I’m using the connection pooling class.
Jetty:
<?xml version="1.0"?>
<!DOCTYPE Configure PUBLIC "-//Mort Bay Consulting//DTD Configure//EN"
"http://jetty.mortbay.org/configure.dtd">
<Configure class="org.mortbay.jetty.webapp.WebAppContext">
<New id="icatDB" class="org.mortbay.jetty.plus.naming.Resource">
<Arg>jdbc/icatDB</Arg>
<Arg>
<New class="org.postgresql.ds.PGPoolingDataSource">
<Set name="serverName">localhost</Set>
<Set name="databaseName">icat2</Set>
<Set name="user">nigel</Set>
<Set name="password"></Set>
</New>
</Arg>
</New>
</Configure>
Tomcat: Example from a different project:
<Context path="/continuum">
<Resource name="jdbc/users"
auth="Container"
type="javax.sql.DataSource"
username="sa"
password=""
driverClassName="org.apache.derby.jdbc.EmbeddedDriver"
url="jdbc:derby:database/users;create=true" />
</Context>
Spring: I am going to pass this into an entity manager:
...
<bean id="entityManagerFactory"
class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="dataSource" ref="dataSource" />
<property name="jpaVendorAdapter">
<bean
class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
<property name="database" value="POSTGRESQL" />
<property name="showSql" value="true" />
<property name="generateDdl" value="true" />
</bean>
</property>
</bean>
<bean id="dataSource" class="org.springframework.jndi.JndiObjectFactoryBean">
<property name="jndiName" value="java:comp/env/jdbc/icatDB"/>
</bean>

So I cheated here. The data source already has a JNDI entrypoint so Spring isn’t involved. However in this next example I need to pass in a String which is a webservice endpoint address:Passing a String:
These kinds of elements are passed via the env namespace. From the Jetty JNDI page it tells me we can only pass in these types:

• java.lang.String
• java.lang.Integer
• java.lang.Float
• java.lang.Double
• java.lang.Long
• java.lang.Short
• java.lang.Character
• java.lang.Byte
• java.lang.Boolean

This is fine for configuration work, which is all we are doing.
Jetty:
<?xml version="1.0"?>
<!DOCTYPE Configure PUBLIC "-//Mort Bay Consulting//DTD Configure//EN"
"http://jetty.mortbay.org/configure.dtd">
<Configure class="org.mortbay.jetty.webapp.WebAppContext">
<New class="org.mortbay.jetty.plus.naming.EnvEntry">
<Arg>icatWebservice</Arg>
<Arg type="java.lang.String">http://hostname:8081/ws/ICAT</Arg>
</New>
</Configure>

Tomcat:

<Context path="/icat"
docBase="/var/home/tomcat/icat.war">
<Environment name="mcatextWebservice"
type="java.lang.String"
value="http://localhost:8180/mcatext/ws"/>
</Context>

Now Spring.

First import the jee namespace into your Spring config:
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
...
xmlns:jee="http://www.springframework.org/schema/jee"
xsi:schemaLocation="...
http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-2.0.xsd">
...
Now we can use the jee:jndi-lookup element in place of a value element:
...
<bean id="icatConnectionManagerBase" scope="session"
class="au.edu.archer.services.icat.ICATWsClientImpl">
<constructor-arg index="0">
<jee:jndi-lookup jndi-name="java:comp/env/icatWebservice"/>
</constructor-arg>
</bean>

There has also been discussion of writing a PropertyPlaceholderConfigurer like bean which can bring all the JNDI into the properties scope so we could just use ${env.property} notation.

Hibernate, spring, and different jars

The situation is this. I had a working application which used Hibernate annotated classes, and JTA for data bindings, within a spring framework. Then I moved the annotated classes into a Jar file, and the application stopped working. Hibernate knew nothing about the classes because the PersistenceAnnotationBeanPostProcessor does not traverse into the JARS on the classpath. Further neither the entity manager or HibernateJpaVendorAdapter have options to specify the explicit paths to the classes.

So, after heaps of trials and tests I’ve had to abandon the JPA approach and use the direct Spring-Hibernate bindings, as they allow you to specify the path to a mappings file. This is a pain, as all my code is written to use an entityManager and now I have to have duplicate implementation which use the hibernate session factory. Perhaps there is a hibernate implementation of the entity manager, but I could not find it.

I used this blog entry for most of the config code.

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