Android net wifi p2p

WifiP2pManager

This class provides the API for managing Wi-Fi peer-to-peer connectivity. This lets an application discover available peers, setup connection to peers and query for the list of peers. When a p2p connection is formed over wifi, the device continues to maintain the uplink connection over mobile or any other available network for internet connectivity on the device.

The API is asynchronous and responses to requests from an application are on listener callbacks provided by the application. The application needs to do an initialization with initialize(Context, Looper, WifiP2pManager.ChannelListener) before doing any p2p operation.

Most application calls need a WifiP2pManager.ActionListener instance for receiving callbacks onSuccess() or onFailure(int) . Action callbacks indicate whether the initiation of the action was a success or a failure. Upon failure, the reason of failure can be one of ERROR , P2P_UNSUPPORTED or BUSY .

An application can initiate discovery of peers with discoverPeers(WifiP2pManager.Channel, WifiP2pManager.ActionListener) . An initiated discovery request from an application stays active until the device starts connecting to a peer ,forms a p2p group or there is an explicit stopPeerDiscovery(WifiP2pManager.Channel, WifiP2pManager.ActionListener) . Applications can listen to WIFI_P2P_DISCOVERY_CHANGED_ACTION to know if a peer-to-peer discovery is running or stopped. Additionally, WIFI_P2P_PEERS_CHANGED_ACTION indicates if the peer list has changed.

When an application needs to fetch the current list of peers, it can request the list of peers with requestPeers(WifiP2pManager.Channel, WifiP2pManager.PeerListListener) . When the peer list is available onPeersAvailable(WifiP2pDeviceList) is called with the device list.

An application can initiate a connection request to a peer through connect(WifiP2pManager.Channel, WifiP2pConfig, WifiP2pManager.ActionListener) . See WifiP2pConfig for details on setting up the configuration. For communication with legacy Wi-Fi devices that do not support p2p, an app can create a group using createGroup(WifiP2pManager.Channel, WifiP2pManager.ActionListener) which creates an access point whose details can be fetched with requestGroupInfo(WifiP2pManager.Channel, WifiP2pManager.GroupInfoListener) .

After a successful group formation through createGroup(WifiP2pManager.Channel, WifiP2pManager.ActionListener) or through connect(WifiP2pManager.Channel, WifiP2pConfig, WifiP2pManager.ActionListener) , use requestConnectionInfo(WifiP2pManager.Channel, WifiP2pManager.ConnectionInfoListener) to fetch the connection details. The connection info WifiP2pInfo contains the address of the group owner groupOwnerAddress and a flag isGroupOwner to indicate if the current device is a p2p group owner. A p2p client can thus communicate with the p2p group owner through a socket connection.

With peer discovery using discoverPeers(WifiP2pManager.Channel, WifiP2pManager.ActionListener) , an application discovers the neighboring peers, but has no good way to figure out which peer to establish a connection with. For example, if a game application is interested in finding all the neighboring peers that are also running the same game, it has no way to find out until after the connection is setup. Pre-association service discovery is meant to address this issue of filtering the peers based on the running services.

With pre-association service discovery, an application can advertise a service for a application on a peer device prior to a connection setup between the devices. Currently, DNS based service discovery (Bonjour) and Upnp are the higher layer protocols supported. Get Bonjour resources at dns-sd.org and Upnp resources at upnp.org As an example, a video application can discover a Upnp capable media renderer prior to setting up a Wi-fi p2p connection with the device.

An application can advertise a Upnp or a Bonjour service with a call to addLocalService(WifiP2pManager.Channel, WifiP2pServiceInfo, WifiP2pManager.ActionListener) . After a local service is added, the framework automatically responds to a peer application discovering the service prior to establishing a p2p connection. A call to removeLocalService(WifiP2pManager.Channel, WifiP2pServiceInfo, WifiP2pManager.ActionListener) removes a local service and clearLocalServices(WifiP2pManager.Channel, WifiP2pManager.ActionListener) can be used to clear all local services.

An application that is looking for peer devices that support certain services can do so with a call to discoverServices(WifiP2pManager.Channel, WifiP2pManager.ActionListener) . Prior to initiating the discovery, application can add service discovery request with a call to addServiceRequest(WifiP2pManager.Channel, WifiP2pServiceRequest, WifiP2pManager.ActionListener) , remove a service discovery request with a call to removeServiceRequest(WifiP2pManager.Channel, WifiP2pServiceRequest, WifiP2pManager.ActionListener) or clear all requests with a call to clearServiceRequests(WifiP2pManager.Channel, WifiP2pManager.ActionListener) . When no service requests remain, a previously running service discovery will stop. The application is notified of a result of service discovery request through listener callbacks set through setDnsSdResponseListeners(WifiP2pManager.Channel, WifiP2pManager.DnsSdServiceResponseListener, WifiP2pManager.DnsSdTxtRecordListener) for Bonjour or setUpnpServiceResponseListener(WifiP2pManager.Channel, WifiP2pManager.UpnpServiceResponseListener) for Upnp.

Note: Registering an application handler with initialize(Context, Looper, WifiP2pManager.ChannelListener) requires the permissions ACCESS_WIFI_STATE and CHANGE_WIFI_STATE to perform any further peer-to-peer operations. Get an instance of this class by calling Context.getSystemService(Context.WIFI_P2P_SERVICE) .

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