3.1 Common Details
The following state diagram depicts how a device implements WFDA2A.
Figure 2: WFDA2A state diagram
A higher-layer trigger moves the protocol from state 1: start, to state 2 (for details, see section 3.1.4).
State 2 consists of two complementary operations: advertise device information and search for proximate devices. When the protocol advertises device information, it can be discovered by a device searching for proximate devices. Conversely, when the protocol is searching for devices, it can discover proximate devices that are advertising their device information.
In state 2, the protocol can transition from one operation to the other. For the protocol and a proximate device to discover each other, the device has to perform the opposite operation to that being performed by the protocol. For example, if the protocol is advertising device information, then for the protocol to be discovered, the proximate device has to be searching for devices. If the protocol and proximate device persistently perform the same operation, only advertise device information or only search for proximate devices, the connection cannot be made.A higher-layer trigger moves the protocol from state 2 to state 3, connecting to a proximate device (for details, see section 3.1.4).
After all of the message processing events and sequencing events have completed (for details, see section 3.1.5), the protocol moves to state 4. If all processing was successful, the connection is made between the protocol and the proximate device; otherwise, the connection fails.