Read and approve bpm work item from ecc

Hi,

we have a BPM workflow on a CE 7.31 system.

My requirement is to read all work item of a user from ECC system, show a list of them and give the opportunity to select a work item and approve/reject it.

I need this because in ECC we have a service for digital sign the attachments in the BPM work item.

BPM/CE have a list of web services or APi to do this?

Thank You

Daniele