hi raymond,
On 7/30/07, Raymond Brandon <[EMAIL PROTECTED]> wrote:
> Hi all,
>
> I have the following problem: in a web application that gets some of
> it's content from jackrabbit, I have to implement a monitor process that
> periodically checks whether the JCR is still alive and usable by the
> application.
>
> I'm testing locally on tomcat 5.0 that hosts my web application which
> uses a remote Oracle database for a part of its data and a JCR which is
> configured to also use a remote Oracle database for a different part of
> its data. My use case is to unplug my network cable to simulate losing a
> connection.
>
> I thought that if I tried to retrieve some content that is also used by
> the application I would get an indication whether the JCR is able to
> retrieve it or not, but it turns out not to be a good choice. The JCR
> caches the information that is retrieved, so if my network cable is in
> place and I access the JCR for some node path containing some content
> and it is retrieved successfully, unplugging the network cable and
> trying to retrieve the same content again will also succeed.
>
> I than had the idea to create a dummy node if it was not already present
> in the JCR or delete it if it wasn't. Similar to the previous attempt, I
> use the Spring JcrTemplate in which I use the JcrCallback interface to
> execute these actions. When the network cable is in place, everything
> works ok (of course). When I unplug, I get the desired behavior that
> calling save() on the session fails after creating a dummy node
> underneath the root. But, when I reconnect my network cable, the JCR
> does not seem to recover from the previous error and throws a
> javax.jcr.ItemNotFoundException for UUID of the dummy node that was
> created in a previous run (see stacktrace). The JCR seems to keep state
> somewhere, which is logical since I get the Session from the same
> sessionfactory in Spring eveytime...
strange; i'd say that calling 'session.refresh(false)' should clear any pendant
transient session state...
anyway, you could try something like this:
boolean checkBackendSanity(Session session) {
try {
session.getNodeByUUID(UUID.randomUUID().toString());
} catch (ItemNotFoundException e) {
// expected
return true;
} catch (RepositoryException e) {
// something's wrong...
return false;
}
}
cheers
stefan
>
> Caused by: javax.jcr.ItemNotFoundException:
> 33d0f734-2ad7-4097-a3b2-fd349d0b0ba2
> at
> org.apache.jackrabbit.core.ItemManager.createItemInstance(ItemManager.ja
> va:467)
> at
> org.apache.jackrabbit.core.ItemManager.getItem(ItemManager.java:323)
> at
> org.apache.jackrabbit.core.NodeImpl.internalAddChildNode(NodeImpl.java:7
> 96)
> at
> org.apache.jackrabbit.core.NodeImpl.internalAddNode(NodeImpl.java:740)
> at
> org.apache.jackrabbit.core.NodeImpl.internalAddNode(NodeImpl.java:687)
> at
> org.apache.jackrabbit.core.NodeImpl.addNode(NodeImpl.java:1912)
> ....
> ....
>
> I'm using JCR version 1.2.1, java 1.4.2, Oracle 9.2.1
>
> Does anybody have an idea on how to tackle this properly?
>
> Raymond
>
> The code:
>
> result = (Boolean) template.execute(new JcrCallback() {
> public Object doInJcr(final Session session) throws
> RepositoryException {
> Boolean success = Boolean.FALSE;
> Node rootNode = session.getRootNode();
> try {
> createDummyNode(rootNode);
> session.save();
> success = Boolean.TRUE;
> } catch (RepositoryException e) {
> // Rollback any changes
> session.refresh(false);
> throw e;
> } finally {
> session.logout();
> }
> return result;
> }
> });
>
> private void createDummyNode(Node rootNode) throws RepositoryException {
> boolean hasNode = false;
> try {
> hasNode = rootNode.hasNode("dummy");
> } catch (RepositoryException e) {}
> if (hasNode) {
> Node dummyNode = rootNode.getNode("dummy");
> dummyNode.remove();
> } else {
> rootNode.addNode(("dummy");
> }
> }
>
> Spring config:
>
> <bean id="jcrTemplate" class="org.springmodules.jcr.JcrTemplate">
> <property name="sessionFactory" ref="jcrSessionFactory" />
> <property name="allowCreate" value="true" />
> </bean>
>
> <bean id="jcrRepository"
> class="nl.anwb.autoportaal.dao.jackrabbit.RepositoryFactoryBean">
> <property name="configuration"
> value="classpath:jcr-repo-jndi.xml"/>
> <property name="repositoryHome"
> value="data/jackrabbit-repository"/>
> </bean>
>
> <bean id="jcrSessionFactory"
> class="org.springmodules.jcr.JcrSessionFactory">
> <property name="repository" ref="jcrRepository" />
> <property name="credentials" ref="credentials"/>
> </bean>
>
> <bean id="credentials" class="javax.jcr.SimpleCredentials">
> <constructor-arg index="0" value="bogus"/>
> <constructor-arg index="1">
> <bean factory-bean="password" factory-method="toCharArray"/>
>
> </constructor-arg>
> </bean>
>
> <bean id="password" class="java.lang.String">
> <constructor-arg index="0" value="somepassword"/>
> </bean>
>
