Leave Request Approval From ESS and MSS to Front End Desk top

Dear Experts,

                  My client requiremt is

Right now they are using ESS and MSS  modules for leave approval and etc.

now Client would like to Approve or Reject the Leave Approval of an employee without loging in to ESS or MSS.

If an employee applied  for a leave in ESS , it should be Display like a widget to the concerned manager once heopened his desktop( non SAP), and from there itself  he would like to approve/ reject that leave application. Once he Approved it  that data has to be updated in SAP.For this project We have taken the ABAP,PI and Basis People help to fulfill the task.

My request is

1) As a HCM consultant what is my role involves

2) Is there Any Sepcified BAPI is available in HCM for this Requirement

Here i mentioned the mail briefly.

1.       Currently, customer is looking only for Desktop Background and Leave Approval/Rejection Functionality as widget.

2.       Customer is expecting to have widget to be made available on the Desktop as Sticker which shows Pending Leave Approvals(from SAP HCM Module) for the user logged into the system. It is agreed by the customer that, this widget will show only Pending Leave Approvals of his reportees and allows Approve or Reject the request only.