problems with optimistic locking/persistence data in EJB3 ac
wiggy Jan 13, 2008 11:40 AMGot a problem thats doing my head in if anyone can explain whats going on. Spent too much time trying to figure this and getting nowhere. Any HELP greatfully received.
I have a simple ejb3 stateless EAR application. it consists of an ejb jar for my entity classes, and an enterprise object access wrapper (EJB equiv of generic DAO pattern for old hibernate - tried this based on EJB3 in action book).
the app is simple - it has a node entity and link entity, and you link nodes to links backwards and forwards (at java level its a bit like a doubly linked list.
I have set transitive persistence for persist and merge actions
essentially i have an external test app that creates some nodes and links them. I use the nodeEAO to persist the 3 nodes and two links in the DB (mysql). This works okay, and the entities are persisted.
client app code outside the conatiner ... ctx = getInitialContext(); aNode = new Node(); bNode = new Node (); cNode = new Node (); uNode = new Node (); // empty zNode = new Node (); // empty aNode.setNodeName("William"); bNode.setNodeName("10 South Close"); cNode.setNodeName("G01 B32"); try { UserTransaction ut = (UserTransaction)ctx.lookup("UserTransaction"); ut.begin(); Link aLink = aNode.addLinkTo(bNode); aNode.addLinkTo(cNode); //update uNode to persisted value uNode = nodeEAO.save(aNode); ut.commit(); } catch (Exception e) {e.printStackTrace(); System.exit(0);} ... then later i call the following if (nodeEAO.removeLink(uNode, zNode)) { System.out.println ("deleted link : \n"); }
The code in the EJB in the container for this looks like
EJB nodeEAO code ... @Stateless public class NodeEAOBean extends EAOBean<Node, Long> implements NodeEAO, NodeEAOLocal, NodeEAORemote { @Resource private SessionContext sc; static final long serialVersionUID =1; ... @TransactionAttribute (TransactionAttributeType.REQUIRED) public boolean removeLink (Node fromNode, Node remoteNode) { List<Link> qres; Logger log = Logger.getLogger("NodeEAOBean"); log.setLevel(org.apache.log4j.Level.DEBUG); if (fromNode == null || remoteNode == null) { log.error("was passed a null reference"); return false; } fromNode = em.merge(fromNode); remoteNode = em.merge(remoteNode); Query q = em.createNamedQuery("findLinksBetweenNodes"); q.setParameter("toNode", remoteNode); q.setParameter("fromNode", fromNode); log.debug("to node details " + remoteNode.getNodeName() + "\n"); qres = (List<Link>)q.getResultList(); if (qres != null && qres.size () == 1) { Link link = qres.get(0); remoteNode.deleteLinkFrom(link); fromNode.deleteLinkTo(link); em.remove(link); return true; } else {return false;} }
when i get to the removeLink call in the client this works and the database is updated and one of my links is deleted.
Next I query for remaining links seen from the first node this calls
... List<Node> nodeList2 = nodeEAO.getConnectedToNodes(uNode); if (nodeList2 != null) { for (Node n : nodeList ) { System.out.println ("got connected node : " + n.getNodeName() + "/n"); } }
on the the ejb server this runs a query to get the result .
@TransactionAttribute (TransactionAttributeType.REQUIRED) public List<Node> getConnectedToNodes (Node fromNode) { Logger log = Logger.getLogger("NodeEAOBean"); log.setLevel(org.apache.log4j.Level.DEBUG); if (fromNode == null ) { log.error("was passed a null reference"); return null; } fromNode = em.merge(fromNode); Query q = em.createNamedQuery("getLinkedNodes"); q.setParameter("fromNode", fromNode); return (List<Node>)q.getResultList(); }
however when i run this i get the foillowing error
Exception in thread "main" javax.ejb.EJBException: javax.persistence.OptimisticLockException at org.jboss.ejb3.tx.Ejb3TxPolicy.handleExceptionInOurTx(Ejb3TxPolicy.java:63)
at org.jboss.aspects.tx.TxPolicy.invokeInOurTx(TxPolicy.java:83)
at org.jboss.aspects.tx.TxInterceptor$Required.invoke(TxInterceptor.java:191)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.aspects.tx.TxPropagationInterceptor.invoke(TxPropagationInterceptor.java:95)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.stateless.StatelessInstanceInterceptor.invoke(StatelessInstanceInterceptor.java:62)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.aspects.security.AuthenticationInterceptor.invoke(AuthenticationInterceptor.java:77)
at org.jboss.ejb3.security.Ejb3AuthenticationInterceptor.invoke(Ejb3AuthenticationInterceptor.java:110)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.ENCPropagationInterceptor.invoke(ENCPropagationInterceptor.java:46)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.asynchronous.AsynchronousInterceptor.invoke(AsynchronousInterceptor.java:106)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.stateless.StatelessContainer.dynamicInvoke(StatelessContainer.java:304)
at org.jboss.aop.Dispatcher.invoke(Dispatcher.java:106)
at org.jboss.aspects.remoting.AOPRemotingInvocationHandler.invoke(AOPRemotingInvocationHandler.java:82)
at org.jboss.remoting.ServerInvoker.invoke(ServerInvoker.java:769)
at org.jboss.remoting.transport.socket.ServerThread.processInvocation(ServerThread.java:573)
at org.jboss.remoting.transport.socket.ServerThread.dorun(ServerThread.java:373)
at org.jboss.remoting.transport.socket.ServerThread.run(ServerThread.java:166)
Caused by: javax.persistence.OptimisticLockException
at org.hibernate.ejb.AbstractEntityManagerImpl.wrapStaleStateException(AbstractEntityManagerImpl.java:642) at org.hibernate.ejb.AbstractEntityManagerImpl.throwPersistenceException(AbstractEntityManagerImpl.java:599)
at org.hibernate.ejb.AbstractEntityManagerImpl.merge(AbstractEntityManagerImpl.java:236)
at org.jboss.ejb3.entity.TransactionScopedEntityManager.merge(TransactionScopedEntityManager.java:188)
at org.softwood.neilsapp.eao.NodeEAOBean.getConnectedToNodes(NodeEAOBean.java:135)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:112)
at org.jboss.ejb3.interceptor.InvocationContextImpl.proceed(InvocationContextImpl.java:166)
at org.jboss.ejb3.interceptor.EJB3InterceptorsInterceptor.invoke(EJB3InterceptorsInterceptor.java:63)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.entity.TransactionScopedEntityManagerInterceptor.invoke(TransactionScopedEntityManagerInterceptor.java:54)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.AllowedOperationsInterceptor.invoke(AllowedOperationsInterceptor.java:47)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.aspects.tx.TxPolicy.invokeInOurTx(TxPolicy.java:79)
at org.jboss.aspects.tx.TxInterceptor$Required.invoke(TxInterceptor.java:191)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.aspects.tx.TxPropagationInterceptor.invoke(TxPropagationInterceptor.java:95)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.stateless.StatelessInstanceInterceptor.invoke(StatelessInstanceInterceptor.java:62)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.aspects.security.AuthenticationInterceptor.invoke(AuthenticationInterceptor.java:77)
at org.jboss.ejb3.security.Ejb3AuthenticationInterceptor.invoke(Ejb3AuthenticationInterceptor.java:110)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.ENCPropagationInterceptor.invoke(ENCPropagationInterceptor.java:46)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.asynchronous.AsynchronousInterceptor.invoke(AsynchronousInterceptor.java:106)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.stateless.StatelessContainer.dynamicInvoke(StatelessContainer.java:304)
at org.jboss.aop.Dispatcher.invoke(Dispatcher.java:106)
at org.jboss.aspects.remoting.AOPRemotingInvocationHandler.invoke(AOPRemotingInvocationHandler.java:82)
at org.jboss.remoting.ServerInvoker.invoke(ServerInvoker.java:769)
at org.jboss.remoting.transport.socket.ServerThread.processInvocation(ServerThread.java:573)
at org.jboss.remoting.transport.socket.ServerThread.dorun(ServerThread.java:373)
at org.jboss.remoting.transport.socket.ServerThread.run(ServerThread.java:166)
at org.jboss.remoting.MicroRemoteClientInvoker.invoke(MicroRemoteClientInvoker.java:163)
at org.jboss.remoting.Client.invoke(Client.java:1634)
at org.jboss.remoting.Client.invoke(Client.java:548)
at org.jboss.aspects.remoting.InvokeRemoteInterceptor.invoke(InvokeRemoteInterceptor.java:62)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.aspects.tx.ClientTxPropagationInterceptor.invoke(ClientTxPropagationInterceptor.java:67)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.aspects.security.SecurityClientInterceptor.invoke(SecurityClientInterceptor.java:53)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.remoting.IsLocalInterceptor.invoke(IsLocalInterceptor.java:74)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.stateless.StatelessRemoteProxy.invoke(StatelessRemoteProxy.java:107)
at $Proxy0.getConnectedToNodes(Unknown Source)
at org.EAOtest.main(EAOtest.java:121)
at org.jboss.aspects.remoting.InvokeRemoteInterceptor.invoke(InvokeRemoteInterceptor.java:74)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.aspects.tx.ClientTxPropagationInterceptor.invoke(ClientTxPropagationInterceptor.java:67)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.aspects.security.SecurityClientInterceptor.invoke(SecurityClientInterceptor.java:53)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.remoting.IsLocalInterceptor.invoke(IsLocalInterceptor.java:74)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.stateless.StatelessRemoteProxy.invoke(StatelessRemoteProxy.java:107)
at $Proxy0.getConnectedToNodes(Unknown Source)
at org.EAOtest.main(EAOtest.java:121)
Caused by: org.hibernate.StaleObjectStateException: Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect): [org.softwood.neilsapp.model.node.Node#1] at org.hibernate.event.def.DefaultMergeEventListener.entityIsDetached(DefaultMergeEventListener.java:261)
at org.hibernate.event.def.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:120)
at org.hibernate.event.def.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:53)
at org.hibernate.impl.SessionImpl.fireMerge(SessionImpl.java:677)
at org.hibernate.impl.SessionImpl.merge(SessionImpl.java:661)
at org.hibernate.impl.SessionImpl.merge(SessionImpl.java:665)
at org.hibernate.ejb.AbstractEntityManagerImpl.merge(AbstractEntityManagerImpl.java:227)
at org.jboss.ejb3.entity.TransactionScopedEntityManager.merge(TransactionScopedEntityManager.java:188)
at org.softwood.neilsapp.eao.NodeEAOBean.getConnectedToNodes(NodeEAOBean.java:135)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:112)
at org.jboss.ejb3.interceptor.InvocationContextImpl.proceed(InvocationContextImpl.java:166)
at org.jboss.ejb3.interceptor.EJB3InterceptorsInterceptor.invoke(EJB3InterceptorsInterceptor.java:63)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.entity.TransactionScopedEntityManagerInterceptor.invoke(TransactionScopedEntityManagerInterceptor.java:54)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.AllowedOperationsInterceptor.invoke(AllowedOperationsInterceptor.java:47)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.aspects.tx.TxPolicy.invokeInOurTx(TxPolicy.java:79)
at org.jboss.aspects.tx.TxInterceptor$Required.invoke(TxInterceptor.java:191)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.aspects.tx.TxPropagationInterceptor.invoke(TxPropagationInterceptor.java:95)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.stateless.StatelessInstanceInterceptor.invoke(StatelessInstanceInterceptor.java:62)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.aspects.security.AuthenticationInterceptor.invoke(AuthenticationInterceptor.java:77)
at org.jboss.ejb3.security.Ejb3AuthenticationInterceptor.invoke(Ejb3AuthenticationInterceptor.java:110)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.ENCPropagationInterceptor.invoke(ENCPropagationInterceptor.java:46)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.asynchronous.AsynchronousInterceptor.invoke(AsynchronousInterceptor.java:106)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.stateless.StatelessContainer.dynamicInvoke(StatelessContainer.java:304)
at org.jboss.aop.Dispatcher.invoke(Dispatcher.java:106)
at org.jboss.aspects.remoting.AOPRemotingInvocationHandler.invoke(AOPRemotingInvocationHandler.java:82)
at org.jboss.remoting.ServerInvoker.invoke(ServerInvoker.java:769)
at org.jboss.remoting.transport.socket.ServerThread.processInvocation(ServerThread.java:573)
at org.jboss.remoting.transport.socket.ServerThread.dorun(ServerThread.java:373)
at org.jboss.remoting.transport.socket.ServerThread.run(ServerThread.java:166)
WHat is wrong here - each method in the bean is defined as tranasctional - so when the delete action is run doesnt the persistence context flushed?.
If so when i run the next query method - which passes the original node as base of the search and merge that inside a new transaction do I get this optimistic error.
if i try to debug this from eclipse i get another error from the server which says a transaction isnt active ! bizarre as its got the required annotation for the method
HELP please anyone who can understand whats wrong.
Exception in thread "main" java.lang.IllegalStateException: [com.arjuna.ats.internal.jta.transaction.arjunacore.inactive] [com.arjuna.ats.internal.jta.transaction.arjunacore.inactive] The transaction is not active! at com.arjuna.ats.internal.jta.transaction.arjunacore.TransactionImple.commitAndDisassociate(TransactionImple.java:1379)
at com.arjuna.ats.internal.jta.transaction.arjunacore.BaseTransaction.commit(BaseTransaction.java:135)
at com.arjuna.ats.jbossatx.BaseTransactionManagerDelegate.commit(BaseTransactionManagerDelegate.java:87)
at org.jboss.aspects.tx.TxPolicy.endTransaction(TxPolicy.java:175)
at org.jboss.aspects.tx.TxPolicy.invokeInOurTx(TxPolicy.java:87)
at org.jboss.aspects.tx.TxInterceptor$Required.invoke(TxInterceptor.java:191)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.aspects.tx.TxPropagationInterceptor.invoke(TxPropagationInterceptor.java:95)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.stateless.StatelessInstanceInterceptor.invoke(StatelessInstanceInterceptor.java:62)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.aspects.security.AuthenticationInterceptor.invoke(AuthenticationInterceptor.java:77)
at org.jboss.ejb3.security.Ejb3AuthenticationInterceptor.invoke(Ejb3AuthenticationInterceptor.java:110)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.ENCPropagationInterceptor.invoke(ENCPropagationInterceptor.java:46)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.asynchronous.AsynchronousInterceptor.invoke(AsynchronousInterceptor.java:106)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.stateless.StatelessContainer.dynamicInvoke(StatelessContainer.java:304)
at org.jboss.aop.Dispatcher.invoke(Dispatcher.java:106)
at org.jboss.aspects.remoting.AOPRemotingInvocationHandler.invoke(AOPRemotingInvocationHandler.java:82)
at org.jboss.remoting.ServerInvoker.invoke(ServerInvoker.java:769)
at org.jboss.remoting.transport.socket.ServerThread.processInvocation(ServerThread.java:573)
at org.jboss.remoting.transport.socket.ServerThread.dorun(ServerThread.java:373)
at org.jboss.remoting.transport.socket.ServerThread.run(ServerThread.java:166)
at org.jboss.remoting.MicroRemoteClientInvoker.invoke(MicroRemoteClientInvoker.java:163)
at org.jboss.remoting.Client.invoke(Client.java:1634)
at org.jboss.remoting.Client.invoke(Client.java:548)
at org.jboss.aspects.remoting.InvokeRemoteInterceptor.invoke(InvokeRemoteInterceptor.java:62)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.aspects.tx.ClientTxPropagationInterceptor.invoke(ClientTxPropagationInterceptor.java:67)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.aspects.security.SecurityClientInterceptor.invoke(SecurityClientInterceptor.java:53)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.remoting.IsLocalInterceptor.invoke(IsLocalInterceptor.java:74)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.stateless.StatelessRemoteProxy.invoke(StatelessRemoteProxy.java:107)
at $Proxy0.removeLink(Unknown Source)
at org.EAOtest.main(EAOtest.java:115)
at org.jboss.aspects.remoting.InvokeRemoteInterceptor.invoke(InvokeRemoteInterceptor.java:74)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.aspects.tx.ClientTxPropagationInterceptor.invoke(ClientTxPropagationInterceptor.java:67)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.aspects.security.SecurityClientInterceptor.invoke(SecurityClientInterceptor.java:53)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.remoting.IsLocalInterceptor.invoke(IsLocalInterceptor.java:74)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.stateless.StatelessRemoteProxy.invoke(StatelessRemoteProxy.java:107)
at $Proxy0.removeLink(Unknown Source)
at org.EAOtest.main(EAOtest.java:115)
the code for the query is defined with the entity.
@Entity @Inheritance(strategy=InheritanceType.SINGLE_TABLE) @DiscriminatorColumn (name="nodeType", discriminatorType=DiscriminatorType.STRING) @DiscriminatorValue ("generic node") @NamedQueries ({ @NamedQuery( name = "findLinksBetweenNodes", query = "SELECT l FROM Link l " + "WHERE (l.fromNode = :fromNode " + "AND l.toNode = :toNode)" ), @NamedQuery( name = "getLinkedNodes", query = "SELECT l.toNode FROM Link l " + "WHERE (l.fromNode = :fromNode) " ) }) public class Node implements Serializable { static final long serialVersionUID = 1; @Id @GeneratedValue @Column(name="nodeID") private Long nodeID; @Version private long version; //enable transitive persistence from owning node to links @OneToMany (mappedBy="fromNode", cascade={CascadeType.PERSIST, CascadeType.MERGE }) @org.hibernate.annotations.Cascade(org.hibernate.annotations.CascadeType.SAVE_UPDATE) protected Set<Link> fromLinks; @OneToMany (mappedBy="toNode", cascade={CascadeType.PERSIST, CascadeType.MERGE }) @org.hibernate.annotations.Cascade(org.hibernate.annotations.CascadeType.SAVE_UPDATE) protected Set<Link> toLinks; // not required and errors on load @Temporal (TemporalType.TIMESTAMP) private Timestamp lastUpdated; @Column(length=255, nullable=false) @NotNull private String nodeName; @Column(length=255) private String aliasName; //calculated: how important is this node private int weight; //as set by a user: how important is this node private int importance; public Long getID () {return nodeID;} public Node () { //initialise the links toLinks = new HashSet<Link>(); fromLinks = new HashSet<Link>(); DateFormat fmt = DateFormat.getDateTimeInstance(); nodeName = "generic node: " + fmt.format(new Date()); } public Node (String name) { if (name != null) this.nodeName = name; else nodeName = "null"; } public long getVersion() {return version;} public String getNodeName () {return nodeName;} public void setNodeName (String name) {this.nodeName = name;} public String getAliasName () {return aliasName;} public void setAliasName (String name) {this.aliasName = name;} public int getImportance () {return importance;} public void setImportance (int imp) {this.importance = imp;} public void incrementImportance () {this.importance++;} public void decrementImportance () {this.importance--;} public void calculateWeight () {/*TODO*/}; protected void setLastUpdated() { Date now = new Date(); lastUpdated = new Timestamp (now.getTime()); } @TransactionAttribute (TransactionAttributeType.REQUIRED) public Link addLinkTo (Node remoteNode) { Link aLink = new Link (); aLink.setName("link from " + this.getNodeName() + " to " + remoteNode.getNodeName()); //set the link relationships aLink.setToNode(remoteNode); aLink.setFromNode(this); //set the node relationships to the joining link this.setLinkTo(aLink); remoteNode.setLinkFrom(aLink); //return the new link return aLink; } public Set<Link> getLinkTo () { return toLinks; } public void setLinkTo (Link link) { toLinks.add(link); } public void deleteLinkTo (Link link) { toLinks.remove(link); } public Set<Link> getLinkFrom () { return fromLinks; } public void setLinkFrom (Link link) { fromLinks.add(link); } public void deleteLinkFrom (Link link) { fromLinks.remove(link); } }