Consider all the problems you could face weeks or months from now, if you're unable to prove that an employee obtained a leave approval from her manager? Unless your business has developed formal HR approval processes, you will likely review, approve or reject important HR requests on an ad-hoc basis.
Many of those, who use SAP HR Approvals app powered by SAP NetWeaver Gateway can now avoid these situations all together.
However, one important consideration that many businesses are facing when integrating with SAP HCM, is how to expose its functionality to mobile devices in days -- not months?
SAP NW Gateway allowed many businesses to accomplish just that. NW Gateway provided a native and most importantly a quick way to integrate with SAP HCM, so that their employees and managers could take action on HR requests anywhere at any time. As exemplified in SAP HR Approvals app, NW Gateway extended the functionality of on-premise SAP HCM, allowing managers to evaluate and respond to approval requests right from their iPhone, and providing employees with quick replies and managers more time to focus on value-added work.
Most importantly, with SAP NW Gateway many organizations were able to build other mobile apps, not just for their HR Approvals, and leveraging the existing data and functionality stored in SAP HCM. By using NW Gateway they significantly streamlined the cost and time required to coordinate common HR business processes by managing and tracking the human tasks involved in these processes. Because HR mobile apps assign tasks, send reminders, track participation, and creates a record of the entire process RIGHT FROM employee’s PHONE, employees can concentrate on performing work instead of chasing people and managing the logistics of the HR process.
Check out this example of SAP 
NW Gateway in action here: https://itunes.apple.com/us/app/sap-hr-approvals/id468092865?mt=8