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
