Generic Attribute Profile
The latest Bluetooth specification uses a service-based architecture
based on the attribute protocol (ATT). All communication in low energy
takes place over the Generic Attribute Profile (GATT). An application
or another profile uses the GATT profile so a client and server can
interact in a structured way.
The server contains a number of attributes,and the GATT Profile defines how to use the Attribute Protocol to discover,read,write and obtain indications. These features support a service-based architecture. The services are used as defined in the profile specifications. GATT enables you to expose service and characteristics defined in the profile specification.