how to generate order code for custom checkout implementation

HI, i am working on payment integration.through that gate way i need to place a order in hybris system. i have address and payment details which i am getting from third party payment merchant. i just used hybris order conformation code to place the order.but i am getting error like order code is not proper.please suggest how to generate order code for custom check out process for placing order.

following is the code snippet i am using for custom order conformation.we are sending order code after conformation.how can i get this order code in my custom order processing.please help on this.

model.addAttribute("orderCode", "ordercode"); model.addAttribute("orderData", orderDetails); model.addAttribute("allItems", orderDetails.getEntries());