javax.bluetooth
Class DiscoveryAgent

java.lang.Object
  javax.bluetooth.DiscoveryAgent

public class DiscoveryAgent
extends java.lang.Object

The DiscoveryAgent class provides methods to perform device and service discovery. A local device must have only one DiscoveryAgent object. This object must be retrieved by a call to getDiscoveryAgent() on the LocalDevice object.

Device Discovery

There are two ways to discover devices. First, an application may use startInquiry() to start an inquiry to find devices in proximity to the local device. Discovered devices are returned via the deviceDiscovered() method of the interface DiscoveryListener. The second way to discover devices is via the retrieveDevices() method. This method will return devices that have been discovered via a previous inquiry or devices that are classified as pre-known. (Pre-known devices are those devices that are defined in the Bluetooth Control Center as devices this device frequently contacts.) The retrieveDevices() method does not perform an inquiry, but provides a quick way to get a list of devices that may be in the area.

Service Discovery

The DiscoveryAgent class also encapsulates the functionality provided by the service discovery application profile. The class provides an interface for an application to search and retrieve attributes for a particular service. There are two ways to search for services. To search for a service on a single device, the searchServices() method should be used. On the other hand, if you don't care which device a service is on, the selectService() method does a service search on a set of remote devices.

Field Summary

static int	CACHED Used with the retrieveDevices() method to return those devices that were found via a previous inquiry.
static int	GIAC The inquiry access code for General/Unlimited Inquiry Access Code (GIAC).
static int	LIAC The inquiry access code for Limited Dedicated Inquiry Access Code (LIAC).
static int	NOT_DISCOVERABLE Takes the device out of discoverable mode.
static int	PREKNOWN Used with the retrieveDevices() method to return those devices that are defined to be pre-known devices.

Method Summary

boolean	cancelInquiry(DiscoveryListener listener) Removes the device from inquiry mode.
boolean	cancelServiceSearch(int transID) Cancels the service search transaction that has the specified transaction ID.
RemoteDevice[]	retrieveDevices(int option) Returns an array of Bluetooth devices that have either been found by the local device during previous inquiry requests or been specified as a pre-known device, depending on the argument.
int	searchServices(int[] attrSet, UUID[] uuidSet, RemoteDevice btDev, DiscoveryListener discListener) Searches for services on a remote Bluetooth device that have all the UUIDs specified in uuidSet.
java.lang.String	selectService(UUID uuid, int security, boolean master) Attempts to locate a service that contains uuid in the ServiceClassIDList of its service record.
boolean	startInquiry(int accessCode, DiscoveryListener listener) Places the device into inquiry mode.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

NOT_DISCOVERABLE

public static final int NOT_DISCOVERABLE

Takes the device out of discoverable mode.

The value of NOT_DISCOVERABLE is 0x00 (0).

See Also:

Constant Field Values

GIAC

public static final int GIAC

The inquiry access code for General/Unlimited Inquiry Access Code (GIAC). This is used to specify the type of inquiry to complete or respond to.

The value of GIAC is 0x9E8B33 (10390323). This value is defined in the Bluetooth Assigned Numbers document.

See Also:

Constant Field Values

LIAC

public static final int LIAC

The inquiry access code for Limited Dedicated Inquiry Access Code (LIAC). This is used to specify the type of inquiry to complete or respond to.

The value of LIAC is 0x9E8B00 (10390272). This value is defined in the Bluetooth Assigned Numbers document.

See Also:

Constant Field Values

CACHED

public static final int CACHED

Used with the retrieveDevices() method to return those devices that were found via a previous inquiry. If no inquiries have been started, this will cause the method to return null.

The value of CACHED is 0x00 (0).

See Also:

retrieveDevices(int), Constant Field Values

PREKNOWN

public static final int PREKNOWN

Used with the retrieveDevices() method to return those devices that are defined to be pre-known devices. Pre-known devices are specified in the BCC. These are devices that are specified by the user as devices with which the local device will frequently communicate.

The value of PREKNOWN is 0x01 (1).

See Also:

retrieveDevices(int), Constant Field Values

Method Detail

retrieveDevices

public RemoteDevice[] retrieveDevices(int option)

Returns an array of Bluetooth devices that have either been found by the local device during previous inquiry requests or been specified as a pre-known device, depending on the argument. The list of previously found devices is maintained by the implementation of this API. A device can be set as a pre-known device in the Bluetooth Control Center. While maintenance of the list of previously found devices is an implementation detail, it is essential to ensure a consistent user experience in what constitutes a list of cached Bluetooth devices. Thus, a Bluetooth API implementation MUST read the list of cached devices from the native side every time the DiscoveryAgent.retrieveDevices() method, if access to the native list is available. If the native Bluetooth implementation does not maintain the list of cached devices, or if the list is not readily available, a Bluetooth API implementation MUST maintain a similar list itself and return this list from the DiscoveryAgent.retrieveDevices() method when asked for CACHED devices. The returned list in either case MUST contain no more than one entry for an individual remote device.

Parameters:

option - CACHED if previously found devices should be returned; PREKNOWN if pre-known devices should be returned

Returns:

an array containing the Bluetooth devices that were previously found if option is CACHED; an array of devices that are pre-known devices if option is PREKNOWN; null if no devices meet the criteria

Throws:

java.lang.IllegalArgumentException - if option is not CACHED or PREKNOWN

startInquiry

public boolean startInquiry(int accessCode,
                            DiscoveryListener listener)
                     throws BluetoothStateException

Places the device into inquiry mode. The length of the inquiry is implementation dependent. This method will search for devices with the specified inquiry access code. Devices that responded to the inquiry are returned to the application via the method deviceDiscovered() of the interface DiscoveryListener. The cancelInquiry() method is called to stop the inquiry.

Parameters:

accessCode - the type of inquiry to complete

listener - the event listener that will receive device discovery events

Returns:

true if the inquiry was started; false if the inquiry was not started because the accessCode is not supported

Throws:

java.lang.IllegalArgumentException - if the access code provided is not LIAC, GIAC, or in the range 0x9E8B00 to 0x9E8B3F

java.lang.NullPointerException - if listener is null

BluetoothStateException - if the Bluetooth device does not allow an inquiry to be started due to other operations that are being performed by the device

See Also:

cancelInquiry(javax.bluetooth.DiscoveryListener), GIAC, LIAC

cancelInquiry

public boolean cancelInquiry(DiscoveryListener listener)

Removes the device from inquiry mode.

An inquiryCompleted() event will occur with a type of INQUIRY_TERMINATED as a result of calling this method. After receiving this event, no further deviceDiscovered() events will occur as a result of this inquiry.

This method will only cancel the inquiry if the listener provided is the listener that started the inquiry.

Parameters:

listener - the listener that is receiving inquiry events

Returns:

true if the inquiry was canceled; otherwise false if the inquiry was not canceled or if the inquiry was not started using listener

Throws:

java.lang.NullPointerException - if listener is null

searchServices

public int searchServices(int[] attrSet,
                          UUID[] uuidSet,
                          RemoteDevice btDev,
                          DiscoveryListener discListener)
                   throws BluetoothStateException

Searches for services on a remote Bluetooth device that have all the UUIDs specified in uuidSet. Once the service is found, the attributes specified in attrSet and the default attributes are retrieved. The default attributes are ServiceRecordHandle (0x0000), ServiceClassIDList (0x0001), ServiceRecordState (0x0002), ServiceID (0x0003), and ProtocolDescriptorList (0x0004).If attrSet is null then only the default attributes will be retrieved. attrSet does not have to be sorted in increasing order, but must only contain values in the range [0 - (2¹⁶-1)].

Parameters:

attrSet - indicates the attributes whose values will be retrieved on services which have the UUIDs specified in uuidSet

uuidSet - the set of UUIDs that are being searched for; all services returned will contain all the UUIDs specified here

btDev - the remote Bluetooth device to search for services on

discListener - the object that will receive events when services are discovered

Returns:

the transaction ID of the service search; this number must be positive

Throws:

BluetoothStateException - if the number of concurrent service search transactions exceeds the limit specified by the bluetooth.sd.trans.max property obtained from the class LocalDevice or the system is unable to start one due to current conditions

java.lang.IllegalArgumentException - if attrSet has an illegal service attribute ID or exceeds the property bluetooth.sd.attr.retrievable.max defined in the class LocalDevice; if attrSet or uuidSet is of length 0; if attrSet or uuidSet contains duplicates

java.lang.NullPointerException - if uuidSet, btDev, or discListener is null; if an element in uuidSet array is null

See Also:

DiscoveryListener

cancelServiceSearch

public boolean cancelServiceSearch(int transID)

Cancels the service search transaction that has the specified transaction ID. The ID was assigned to the transaction by the method searchServices(). A serviceSearchCompleted() event with a discovery type of SERVICE_SEARCH_TERMINATED will occur when this method is called. After receiving this event, no further servicesDiscovered() events will occur as a result of this search.

Parameters:

transID - the ID of the service search transaction to cancel; returned by searchServices()

Returns:

true if the service search transaction is terminated, else false if the transID does not represent an active service search transaction

selectService

public java.lang.String selectService(UUID uuid,
                                      int security,
                                      boolean master)
                               throws BluetoothStateException

Attempts to locate a service that contains uuid in the ServiceClassIDList of its service record. This method will return a string that may be used in Connector.open() to establish a connection to the service. This method MUST return immediately after a suitable service (i.e. a service that matches the specified UUID) is found. The Bluetooth inquiry or the Bluetooth service discovery MUST NOT continue after a suitable service is found. Note that if there are several suitable services in the vicinity, different invocations of this method MAY produce different results (i.e. return connection strings pointing at different services). This is because Bluetooth inquiry and service discovery processes are non-deterministic by their nature.

Parameters:

uuid - the UUID to search for in the ServiceClassIDList

security - specifies the security requirements for a connection to this service; must be one of ServiceRecord.NOAUTHENTICATE_NOENCRYPT, ServiceRecord.AUTHENTICATE_NOENCRYPT, or ServiceRecord.AUTHENTICATE_ENCRYPT

master - determines if this client must be the master of the connection; true if the client must be the master; false if the client can be the master or the slave

Returns:

the connection string used to connect to the service with a UUID of uuid; or null if no service could be found with a UUID of uuid in the ServiceClassIDList

Throws:

BluetoothStateException - if the Bluetooth system cannot start the request due to the current state of the Bluetooth system

java.lang.NullPointerException - if uuid is null

java.lang.IllegalArgumentException - if security is not ServiceRecord.NOAUTHENTICATE_NOENCRYPT, ServiceRecord.AUTHENTICATE_NOENCRYPT, or ServiceRecord.AUTHENTICATE_ENCRYPT

See Also:

ServiceRecord.NOAUTHENTICATE_NOENCRYPT, ServiceRecord.AUTHENTICATE_NOENCRYPT, ServiceRecord.AUTHENTICATE_ENCRYPT