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Spring and Hibernate: Multiple connections, thread safe

I have an existing Project working fine, but now I have to implement a Backup System that is executed exery day and dumps the Database to a File. I want to solve this using a ScheduledTask, but this means that there is another Thread using Hibernate.
My Question: How exactly can I make Hibernate Thread safe?
I have the following code-(snippets):
In applicationContext.xml
<bean id="myEmf"
class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="dataSource" ref="dbDataSource" />
<property name="packagesToScan" value="redb.main.core.model" />
<property name="jpaVendorAdapter">
<bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter" />
</property>
<property name="jpaProperties">
<props>
<prop key="hibernate.hbm2ddl.auto">validate</prop>
<prop key="hibernate.dialect">org.hibernate.dialect.SQLServer2008Dialect</prop>
<!-- <prop key="hibernate.enable_lazy_load_no_trans">true</prop> -->
</props>
</property>
</bean>
<!-- Transaction Management -->
<tx:annotation-driven transaction-manager="txManager" />
<bean id="txManager" class="org.springframework.orm.jpa.JpaTransactionManager">
<property name="entityManagerFactory" ref="myEmf" />
</bean>
<bean id="persistenceExceptionTranslationPostProcessor"
class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor" />
So I can get the EntityManager by
#PersistenceContext
protected EntityManager entityManager;
But if i understood it correctly, every Thread needs its own EntityManager from the EntityManagerFactory.
How can I create a new EntityManager in an other class?
I have no persistence.xml. Do I have to create it?

He-he. Welcome in the hell.
The main problem, that spring tries to do that with an aspect-based solution. Although this is buggy (or undebuggable), in trivial cases it can work.
The general answer to your question is that the EntityManagerFactory can be a global, static object in your software, although I were stoned if I simply used that.
By default, the spring aop "weaves" your application on deployment, finds all of the database entity classes by their annotations, and wraps their methods to provide always an existing entitymanager. This is the theory. But it is not the practice.
The practice is that you have very little control over what exactly will happen.
What I did: there is a servlet filter named org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter, which can open an entitymanager for every request, and flush/close that on need. Yes, its name is about "views", but soon its name is its first bug: practically we had to call it as "requesttransactionfilter" or such. It hasn't anything with the MVC views to do, it is working on the http request entities coming from your servlet container.
If you don't like to use servlet filters in a spring application, there is a also a spring interceptor named OpenEntityManagerInViewInterceptor with the very similar functionality, too.
Programmatically, you can generate an EntityManager from an EntityManagerFactory by its createEntityManager() method.
Happy googling! You are on the begin of a long way.

Manually open a hibernate session with Spring config

The issue I am having is that I use Spring to manage and load hibernate for my web application. I am currently using OpenSessionInViewFilter. This works as intended when I am viewing the application, but not so well when I am trying to access hibernate from non-view related activities such as a Quartz task or some Runnable thread I create to help with some tasks. This causes the Lazy initialize exception and no session available exceptions to occur.
Here is how I currently use Spring to manage Hibernate
<bean id="mainDataSource"
class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
[..DB config..]
</bean>
<bean id="sessionFactory"
class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
<property name="dataSource">
<ref bean="mainDataSource"/>
</property>
</bean>
<bean id="txManager"
class="org.springframework.orm.hibernate3.HibernateTransactionManager">
<property name="sessionFactory"><ref local="sessionFactory"/></property>
<property name="dataSource"><ref local="mainDataSource"/></property>
</bean>
I then configure DAO objects which extend HibernateDaoSupport and inject them into service classes
<bean id="myDAO"
class="package.myDAO">
<property name="sessionFactory">
<ref bean="sessionFactory" />
</property>
</bean>
<bean id="mySvcTarget" class="package.myService">
<property name="myDAO"><ref bean="myDAO"/></property>
</bean>
<bean id="myService"
class="org.springframework.transaction.interceptor.TransactionProxyFactoryBean">
<property name="transactionManager">
<ref bean="txManager"/>
</property>
<property name="target">
<ref bean="mySvcTarget"/>
</property>
<property name="transactionAttributes">
<props>
<prop key="*">PROPAGATION_REQUIRED</prop>
</props>
</property>
</bean>
So then in my application, myService is injected into my controller classes so I use that to get access to my DAO's. For my situation though it appears I need to access my DAO's (or service preferably) some other way and manually open and close my hibernate sessions since my service classes only seem to be open during view session. I am not exactly sure the best way to do this. All the hibernate configurations are there already in Spring so I'm assuming its just a matter or calling them somehow.

First of all those additional services that you're using (non-views) should be visible by Spring. The simplest way to do it is to use #Service annotation. And to make it work you can add <context:component-scan base-package="your.package"> in your configuration.
After this, if Spring sees your service as a bean, it should be enough to use #Transactional annotation to have Hibernate session in it.

Configuring JPA in Spring application

I am configuring Spring to use JPA by using Hibernate implementation. However I don't understand the process completly. I have gotten it to work by following different blogs etc. I have used EJB 3.1 and there I had a persistence.xml. However in spring I declared a LocalContainer...Bean and provided some properties to it, and I have no persistence.xml. Could someone explain how it works in Spring and what the declared bean is?
<bean id="emf" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="dataSource" ref="dataSource" />
<property name="jpaVendorAdapter">
<bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter" />
</property>
<property name="packagesToScan" value="com.company.domain" />
<property name="jpaProperties">
<props>
<prop key="hibernate.dialect">
org.hibernate.dialect.PostgreSQL82Dialect
</prop>
</props>
</property>
</bean>

There are different flavors of Spring Configuration with JPA, one which requires persistence.xml and other which requires just bean declarations(no persistence.xml).
I am going to take up the Case-2 in your scenario:
The main reasons we want a persistence.xml is because of the following reasons:
Database connectivity details.
Java classes which are treated as Entities or packages in which to scan for Entities.
Other vendor specific settings like hibernate.show_sql or similar stuff.
Now if spring provides a way to mention all this together in bean configurations then there is no need to have the persistence.xml.
In case of your bean definitions, lets break it down.
<bean id="emf" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="dataSource" ref="dataSource" />
<property name="jpaVendorAdapter">
<bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter" />
</property>
<property name="packagesToScan" value="com.company.domain" />
<property name="jpaProperties">
<props>
<prop key="hibernate.dialect">
org.hibernate.dialect.PostgreSQL82Dialect
</prop>
</props>
</property>
</bean>
First property, dataSource already contains the database settings.
Second property, jpaVendorAdapter is a property specific to Spring
Third property, packagesToScan this is a property of Spring to scan for entities, this we either do in persistence.xml by using "class" tags by mentioning each class FQN.
Fourth property, jpaProperties as the name suggests can either be in Spring or in persistence.xml
e.g.
<property name="hibernate.dialect" value="org.hibernate.dialect.PostgreSQL82Dialect" />
Since you have all the configurations already in Spring bean, there's no need to have a persistence.xml
Just to add a FootNote:
Spring 3.1 provides an alternative: LocalContainerEntityManagerFactoryBean that accepts a 'packagesToScan' property, specifying base packages to scan for #Entity classes.
Hope this answer your queries.

No Hibernate Session bound to thread, and configuration does not allow creation of non-transactional one here

What is this error about? "No Hibernate Session bound to thread, and configuration does not allow creation of non-transactional one here".
My spring config file looks something like this.
<bean id="jndiDataSource"
class="org.springframework.jndi.JndiObjectFactoryBean">
<property name="jndiName">
<value>java:/devDS</value>
</property>
</bean>
<bean id="stsaDBFactory"
class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">
<property name="dataSource" ref="jndiDataSource" />
<property name="annotatedClasses">
<list>
<value>xx.yy.zz.User</value>
<value>xx.yy.UserResponse</value>
</list>
</property>
<property name="hibernateProperties">
<props>
<prop key="hibernate.show_sql">true</prop>
<prop key="hibernate.hbmddl.auto">create</prop>
</props>
</property>
</bean>
<!-- ################################### Aspects ################################################## -->
<bean id="txManager"
class="org.springframework.orm.hibernate3.HibernateTransactionManager">
<property name="sessionFactory">
<ref local="stsaDBFactory" />
</property>
</bean>
All the DAO test passes when i test them outside of the container using junit. When I deploy it in jBoss as a portal app,I get this exception. Also it works fine if i remove the portal specific configuration and make it a simple web app and deploy it on jboss.Any idea?

You have defined a TransactionManager in your spring config but you are trying to execute a hibernate query in a method that is not transactional. Try adding #Transactional to your method or class.

I got around this problem by specifying the current_session_context_class in hibernate config to be "thread", as per the simple configuration shown in the hibernate configuration documentation.
But it recommends that its not safe for production usage.
Trying to add the following in your hibernate config should also help:
<property name="current_session_context_class">org.hibernate.context.ThreadLocalSessionContext</property>
Check out http://docs.jboss.org/hibernate/core/3.6/reference/en-US/html/architecture.html#architecture-current-session for more details.

How can I define multiple sessionfactory instances in Spring?

I would like to have multiple Hibernate SessionFactories in a spring application, all of them with identical configurations except for the DataSource. Ideally, I would acquire a particular SessionFactory by name. I need to be able to do this based on runtime state, and it isn't possible to determine which session factories I will need at application startup time. Basically, I need a SessionFactoryTemplate or something like it.
Is this possible? How do I go about doing it?

You might define an abstract bean and use bean inheritance. This means you'll have a bean definition that works as a template and you may have multiple beans just copying the attributes set by the parent bean.
Here's an example:
<bean id="abstractSessionFactory" abstract="true"
class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
<property name="mappingResources">
<list>
<value>product.hbm.xml</value>
</list>
</property>
<property name="hibernateProperties">
<value>
hibernate.dialect=org.hibernate.dialect.HSQLDialect
</value>
</property>
</bean>
<bean id="mySessionFactory" parent="abstractSessionFactory">
<property name="dataSource" ref="myDataSource"/>
...
</bean>
<bean id="mySessionFactory2" parent="abstractSessionFactory">
<property name="dataSource" ref="myDataSource2"/>
...
</bean>
Using the attribute 'abstract' you ensure that bean won't be instantiated and it will be used just as a template.
More info here: link text

Are you sure you need multiple SessionFactories? If all the mappings/configurations are the same and you just have multiple identical databases (e.g. in a multi-tenant app?), then how about having a single SessionFactory that connects to a DataSource which dynamically supplies the appropriate database connection?
See this question for more details:
And this blog post on Dynamic DataSource Routing in Spring.

I have no idea what your current bean definition looks like now, but wouldn't you just ... define a second SessionFactory?
<bean id="mySessionFactory1"
class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
<property name="dataSource" ref="myDataSource1"/>
<property name="mappingResources">
<list>
<value>product.hbm.xml</value>
</list>
</property>
<property name="hibernateProperties">
<value>
hibernate.dialect=org.hibernate.dialect.HSQLDialect
</value>
</property>
</bean>
<bean id="mySessionFactory2"
class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
<property name="dataSource" ref="myDataSource2"/>
...
</bean>
You could then simply just wire your DAOs up with one sessionFactory vs the other:
<bean id="myProductDao" class="product.ProductDaoImpl">
<property name="sessionFactory" ref="mySessionFactory1"/>
</bean>
<bean id="myCompanyDao" class="product.ProductDaoImpl">
<property name="sessionFactory" ref="mySessionFactory2"/>
</bean>

I don't know of an easy solution for your problem using Spring.
However, you could be able to use Hibernate Interceptors, provided that your particular databases/data-sources can be reached through one master/admin database connection. This blog post explains how in detail, but the gist of it is to dynamically replace table names in SQL statements that Hibernate generates, with qualified names identifying different databases. This is relatively easy to understand and maintain, and works well in my company's multi-tenant set-up.
Apart from that, you can try writing your own TransactionManager, using the HibernateTransactionManager as a starting point, adding support for working with multiple session factories. However, this would mean you having to really dive into Spring ORM support internals, and that is something I tried, but then scrapped in favor of the first approach. I'm sure it can be done with moderate effort, but the previous solution was already doing the job for us.