invalid reference, performance, db access, etc...
jstachera Dec 1, 2006 6:58 AMI 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