Xero & PHP Integration

Background: My application is a cloud based E-Procurement system. It allows users to raise requisitions, approve, generate purchase order and receive supplier Invoices. I would want to integrate it to Xero. How integration will work: Once a user receives an invoice from supplier, they will capture it on my system for approval . When it is approved it will then be pushed to Xero. What you are required to do: Write a PHP API file with the following functions 1. public function newSupplierInvoice($aParam = array()). This function is responsible for writing a invoice into xero and return a unique ID 2. public function getSupplierInvoiceStatus($aParam = array()). This finction will be responsible for determining the status of a supplier invoice that was sent to xero e.g. if it was paid or not. NB: You will not be responsible for writing code to get supplier invoices into my E-Procurement application or writing back. NB: You must have done Xero integration in the past.