Definition of terms: activity, task, job, execution, ...

[jesper1]

There are lots of concepts in Activiti, such as: deployments, processes, activities, tasks, jobs and executions.

Unfortunately user manual does not clearly define these terms, and for someone new to Activiti and BPMN it is hard to understand what exactly is what.

Is there a clear description of these terms somewhere? Some of the questions I have are:

What is an execution?

What is the difference between an execution and a process instance?

What is the difference between an activity, a task and a job?

[jbarrez]

"What is an execution?"

A pointer to where you are in the process instance currently.

"What is the difference between an execution and a process instance?"

A process instance == a collection of executions, structured as a tree and stored relationally

"What is the difference between an activity, a task and a job?"

Activity = a step in the process, typically rounded rectangle in BPMN

task = something a user/system has to do

job = a timer or an async continutation of a process