How to add open functionality in integrated BPMN modeler

I integrated the bpmn modeler in my local system but in that, I can dowload BPMN diagram and download svg file.
But I can not open previously draw bpmn diagram in that . How can it possible please give me solution?

What did you try? What did not work?

I was trying to view the previously drawn bpmn diagram for example today I draw half diagram and tomorrow I want to see that half draw diagram and continue that drawing then how can it possible because I integrate the properties panel example in that they didn’t gave open functionality only download functionality provided. Like here we can open diagram even they provided left hand side corner open image button like that I want to implement.
is it available readily? if not please give me some idea for that?