Custom assignment via camunda:candidateUsers/camunda:assignee using Spring Bean

[Melissa Palmer]

Hi

I'm looking at all the alternatives for assigning a task to a user/group that Camunda has on offer to workout what would be best for us to use. 

I'm wanting to use what's described at: http://docs.camunda.org/latest/api-references/bpmn20/#tasks-user-task in relation to Spring Beans. Documentation has the following information: 

"When using Spring or CDI it is possible to use the custom assignment attributes as described in the section above and delegate to a bean using a task listener with an expression that listens to task create events. In the following example, the assignee will be set by calling the findManagerOfEmployee on the ldapService Spring/CDI bean. The emp parameter that is passed is a process variable>."

Where you can then use: 

<userTask id="task" name="My Task" camunda:assignee="${ldapService.findManagerForEmployee(emp)}"/>

or

<userTask id="task" name="My Task" camunda:candidateUsers="${ldapService.findAllSales()}"/>

I have created the FakeLdapService class as in the docs and configured a bean within the Spring applicationContext.xml file as follows: 

 <bean id="ldapService" class="co.za.itdynamics.assignment.FakeLdapService" />

However am always getting errors and cannot get this working

1) For the "camunda:assignee="${ldapService.findManagerForEmployee(emp)}"" option on server startup (if using the Started implementation of InitialisingBean runtimeService.startProcessInstanceByKey("customassignment"); ) I get the following error:

SEVERE: Error while closing command context
org.camunda.bpm.engine.ProcessEngineException: Error while evaluating expression: ${ldapService.findManagerForEmpl
oyee(emp)}. Cause: Could not lookup beanmanager in jndi. If no jndi is available, set the beanmanger to the 'local
Instance' property of this class.
        at org.camunda.bpm.engine.impl.el.JuelExpression.getValue(JuelExpression.java:61)
        at org.camunda.bpm.engine.impl.bpmn.behavior.UserTaskActivityBehavior.handleAssignments(UserTaskActivityBe
havior.java:114)
        at org.camunda.bpm.engine.impl.bpmn.behavior.UserTaskActivityBehavior.execute(UserTaskActivityBehavior.jav
a:97)...
.....
....
...
...
...

2) For the "camunda:candidateUsers="${ldapService.findAllSales()}"/>" option. Server starts up correctly... however at run time when I try to move a process to the task with this configuration I get the following error: 

Server Error: Cannot submit task form 531a76a3-3e70-11e4-90f1-d4bed948baf9: Unknown property used in expression: ${ldapService.findAllSales()}. Cause: Cannot resolve identifier 'ldapService'

Is there any steps that I have missed here?

Thanks

Melissa

[Melissa Palmer]

UPDATE: there seems to be a problem with my deployment, as using the same wars within the "camunda-bpm-tomcat-7.1.0-Final" webapps all works 100% 

Problem sees to be with the setup/config of "Install the platform on a vanilla Tomcat" using this setup it seems that none of my Java classes from a process war can be see on when initiating a process on this server config setup. 

I getting errors such as:

Server Error: Cannot instantiate process definition myassignmenthandler:4:76296a0b-3e87-11e4-9ae7-d4bed948baf9: couldn't instantiate class org.camunda.bpm.TestClass

Class is in the webapp under "\WEB-INF\classes" and using the very same war on the "camunda-bpm-tomcat-7.1.0-Final" server works correctly. 

Thanks

Melissa

[Christian Lipphardt]

Hi Melissa,

Please make sure you added the platform's boot listener [1] and bpm-platform.xml to your tomcat installation.

[1] http://docs.camunda.org/latest/guides/installation-guide/tomcat/#bpm-platform-install-the-platform-on-a-vanilla-tomcat-add-bpm-bootstrap-server-listener

[2] http://docs.camunda.org/latest/guides/installation-guide/tomcat/#bpm-platform-install-the-platform-on-a-vanilla-tomcat-add-bpm-platformxml

Cheers,

Christian

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[Melissa Palmer]

I have just managed to solve the problem of "Cannot instantiate process definition"... I was using tomcat: 7.0.27... I now switched to 7.0.55 and managed to get everything working. 

I am still getting the initial issue: I cannot use Spring Bean for assignments: eg:  camunda:assignee="${ldapService.findManagerForEmployee(emp)}"

I am seeing the following error::

Server Error: Cannot instantiate process definition customassignment:1:ac2fb8cc-3ea2-11e4-949f-d4bed948baf9: Error while evaluating expression: ${ldapService.findManagerForEmployee(emp)}. Cause: Could not lookup beanmanager in jndi. If no jndi is available, set the beanmanger to the 'localInstance' property of this class.

@Christian thank you.. yes I do have that config setup correctly. 

Melissa

[Christian Lipphardt]

Hi Melissa,

You need to package the camunda-engine-cdi maven dependency [1] with compile scope inside your maven project.

Besides, if you want to use CDI on Tomcat, you need to install an CDI implementation like Weld in Tomcat.

A good installation guide seems to be [2].

[1] http://docs.camunda.org/latest/guides/getting-started-guides/#apache-maven-cdi-module

[2] http://nerdwin15.com/2014/01/using-weld-cdi-jsf-and-jax-rs-in-tomcat/

Cheers,

Christian

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