Nearby Connections supports different Strategies for advertising and discovery.
The best
Strategy
to use depends on the use case.
P2P_CLUSTER
P2P_CLUSTER is a peer-to-peer strategy that supports an M-to-N, or
cluster-shaped, connection topology. In other words, this enables connecting
amorphous clusters of devices within radio range (~100m), where each device can
both initiate outgoing connections to M other devices and accept incoming
connections from N other devices.
This is the default strategy, equivalent to calling the deprecated Connections API methods with no Strategy parameter.
This strategy is more flexible in its topology constraints than P2P_STAR,
but results in lower bandwidth connections. It is good for use cases with
smaller payloads that require a more mesh-like experience, such as multiplayer
gaming.
Permissions
In order to use this Strategy, the app must have the following permissions declared:
- BLUETOOTH
- BLUETOOTH_ADMIN
- ACCESS_WIFI_STATE
- CHANGE_WIFI_STATE
Additionally, on devices running Marshmallow (and onwards), Location must be turned on, and the following additional permission is required:
- ACCESS_COARSE_LOCATION
P2P_STAR
P2P_STAR is a peer-to-peer strategy that supports a 1-to-N, or star-shaped,
connection topology. In other words, this enables connecting devices within
radio range (~100m) in a star shape, where each device can, at any given time,
play the role of either a hub (where it can accept incoming connections from N
other devices), or a spoke (where it can initiate an outgoing connection to a
single hub), but not both.
This strategy lends itself best to situations where there is one device advertising, and N devices which discover the advertiser, though you may still advertise and discover simultaneously if required.
This strategy is more strict in its topology constraints than P2P_CLUSTER, but
results in higher bandwidth connections. It is good for high-bandwidth use cases
such as sharing a video to a group of friends.
Permissions
In order to use this Strategy, the app must have the following permissions declared:
- BLUETOOTH
- BLUETOOTH_ADMIN
- ACCESS_WIFI_STATE
- CHANGE_WIFI_STATE
Additionally, on devices running Marshmallow (and onwards), Location must be turned on, and the following additional permission is required:
- ACCESS_COARSE_LOCATION