Need example in PHP or Ruby for Invoices API

Need example in PHP or Ruby for Invoices API

Hi guys, 

After reading the ZOHO API, I need some example in PHP or Ruby to start. I am trying to get invoices data. Do I need to get both API key and Ticket to get data ( https://www.zoho.com/invoice/api/index.html) ? How do I pass in parameters ? 


Thanks much