[jboss-user] [JBoss jBPM] - invalid reference, performance, db access, etc...
I am working on web application and I found some problems with JbpmContext. There are some
issues that I am not fully aware:
1. If I do not close the context no changes will be saved to the database.
2. If for example I will get some reference to jbpm object:
| TaskInstance taskInstance = context.getTaskInstance(wid);
|
and for some reason I close the context then from that time on the reference to
taskInstance is invalid end every attempt to call some method leads to exception ->
"context was closed" - or smth like that.
Therefore, when I create my TaskInstance Bean (actually JbpmWorkItem) in the constructor I
initialize all the fields that are used by getters methods of the bean.
| public class JbpmWorkItem implements IWorkItem {
| static Log log = new Log();
| /**
| * session
| */
| JbpmDefSession session;
| /**
| * work item id
| */
| long workItemId;
| /**
| * process instance id
| */
| long processInstanceId;
| /**
| * process definition id
| */
| long processDefinitionId;
| /**
| * CurrentProcessObjectName
| */
| String currentProcessObjectName;
|
|
| /*
| * Task instance - actuall jbpm work item (task to do)
| */
|
| /** Cons
| * @param session - def session
| * @param wid - work item id
| * @throws JbpmAtflowException
| */
| public JbpmWorkItem(DefSession session, long wid) throws Exception {
| this.session = (JbpmDefSession)session;
| this.workItemId = wid;
| /* getContext() creates new context for logged user*/
| JbpmContext context = this.session.getContext();
| try {
| TaskInstance taskInstance = context.getTaskInstance(wid);
| processInstanceId = taskInstance.getToken().getProcessInstance().getId();
| processDefinitionId =
taskInstance.getToken().getProcessInstance().getProcessDefinition().getId();
| currentProcessObjectName = taskInstance.getToken().getNode().getName();
| }
| catch (Exception e) {
| log.error("Could not create work item: " + wid + ", actor: " +
session.getLoggedOnUser().getName());
| throw new JbpmAtflowException("Could not create work item: " + wid +
", actor: " + session.getLoggedOnUser().getName(), e);
| }
| finally {
| context.close();
| }
| }
|
and here is the question is it correct way ?
My purpose of doing that was to minimize the number of accesses to the database. Since If
I put the code with creating new context and closing it in every getter method just to
access jbpm object it will probably decrease the performance.
Am I right ? or Is Jbpm doing some caching so not every call to jbpm object method leads
to database access to get the data ?
BR,
Jurek
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