So there is a method in REST API which allows us to create the signal which is caught by signal start events and signal catching events. (http://www.activiti.org/userguide/#_signal_event_received) There is a working feature to send some variables with that signal - I've tried it and the process instance which is created by that REST method actually has the variables I've sent with the signal. How can I describe the same signal throwing event (which will have some variables along the signal) in BPMN model? Userguide and Google searching do not actually help me on this one.
P. S. I suppose I will give some context on why do I need it in first place. There is some workflow process which starts at 'one process per day' rate. At the evening the process instance should pass some data to the next process instance and finish, and the next day process is created. My point of view on it is: we send the signal with some variables at the very end of the process, and start the next process with the signal start event.
Hmm, indeed you can't do that at the moment. It would be a nice feature to add. As a workaround you could use a service task right now that does the runtimeService.signalReceived programmatically.
