If you want to start a specific workflow on server side in an action of your life-cycle object, it's straight forward. Simply use the workflow access object and call one method:

WorkflowAccess wfa = WorkflowAccess.getCurrentInstance();
Obejct id = wfa.startWorkflow(worfklowNameOrId);

Be careful if you run above code outside the life cycle scope because

WorkflowAccess.getCurrentInstance();

tries to get the workflow access object via SessionContext.

If you don't run inside the life cycle scope, use

WorkflowAccess wfa = new WorkflowAccess();
wfa.setDBAccess(dbAccess);

instead.