Automation of our Billing and Purchase Systems

We get orders through 5 different sources , we want to automate these orders so that as soon as we get them, the invoice should get generated automatically, printout of invoice on printer happens automatically, trigger to barcode machine to generate barcode also happens automatically. These should get registered as sales in our accounting software ZOHO. This is an initial one time project. However as we expand our company we will require more such automation services. We are looking for independent freelancer who can automate this using any automation software. Most of the applications we use have APIs- so integration should be possible.