Interface Driver
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public interface Driver
ADriver
service object must be registered by each Driver bundle wishing to attach to Device services provided by other drivers. For each newly discoveredDevice
object, the device manager enters a bidding phase. TheDriver
object whosematch(ServiceReference)
method bids the highest for a particularDevice
object will be instructed by the device manager to attach to theDevice
object.- See Also:
Device
,DriverLocator
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description java.lang.String
attach(org.osgi.framework.ServiceReference<?> reference)
Attaches this Driver service to the Device service represented by the givenServiceReference
object.int
match(org.osgi.framework.ServiceReference<?> reference)
Checks whether this Driver service can be attached to the Device service.
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Method Detail
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match
int match(org.osgi.framework.ServiceReference<?> reference) throws java.lang.Exception
Checks whether this Driver service can be attached to the Device service. The Device service is represented by the givenServiceReference
and returns a value indicating how well this driver can support the given Device service, orDevice.MATCH_NONE
if it cannot support the given Device service at all.The return value must be one of the possible match values defined in the device category definition for the given Device service, or
Device.MATCH_NONE
if the category of the Device service is not recognized.In order to make its decision, this Driver service may examine the properties associated with the given Device service, or may get the referenced service object (representing the actual physical device) to talk to it, as long as it ungets the service and returns the physical device to a normal state before this method returns.
A Driver service must always return the same match code whenever it is presented with the same Device service.
The match function is called by the device manager during the matching process.
- Parameters:
reference
- theServiceReference
object of the device to match- Returns:
- value indicating how well this driver can support the given
Device service, or
Device.MATCH_NONE
if it cannot support the Device service at all - Throws:
java.lang.Exception
- if this Driver service cannot examine the Device service
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attach
java.lang.String attach(org.osgi.framework.ServiceReference<?> reference) throws java.lang.Exception
Attaches this Driver service to the Device service represented by the givenServiceReference
object.A return value of
null
indicates that this Driver service has successfully attached to the given Device service. If this Driver service is unable to attach to the given Device service, but knows of a more suitable Driver service, it must return theDRIVER_ID
of that Driver service. This allows for the implementation of referring drivers whose only purpose is to refer to other drivers capable of handling a given Device service.After having attached to the Device service, this driver may register the underlying device as a new service exposing driver-specific functionality.
This method is called by the device manager.
- Parameters:
reference
- theServiceReference
object of the device to attach to- Returns:
null
if this Driver service has successfully attached to the given Device service, or theDRIVER_ID
of a more suitable driver- Throws:
java.lang.Exception
- if the driver cannot attach to the given device and does not know of a more suitable driver
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