* Copyright (c) OSGi Alliance (2002, 2011). All Rights Reserved.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
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* distributed under the License is distributed on an "AS IS" BASIS,
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Service objects registered under the Producer interface are expected to
produce values (internally generated or from external sensors). The value can
be of different types. When delivering a value to a
Wire object, the
Producer service should coerce the value to be an instance of one of the
types specified by
. The classes are specified in
order of preference.
When the data represented by the Producer object changes, this object should
send the updated value by calling the
update method on each of
Wire objects passed in the most recent call to this object's
Wire objects will
pass the value on to the associated
Consumer service object.
The Producer service may use the information in the
properties to schedule the delivery of values to the
Producer service objects must register with a
service.pid and a
property. It is recommended
that a Producer service object also registers with a
service.description property. Producer service objects must register
property if the
Producer service will be performing filtering instead of the
If an exception is thrown by a Producer object method, a
WireAdminEvent of type
broadcast by the Wire Admin service.
Security Considerations. Data producing bundles will require
ServicePermission[Producer,REGISTER] to register a Producer service.
In general, only the Wire Admin service should have
ServicePermission[Producer,GET]. Thus only the Wire Admin service may
directly call a Producer service. Care must be taken in the sharing of
Wire objects with other bundles.
Producer services must be registered with scope names when they can send
different types of objects (composite) to the Consumer service. The Producer
service should have
WirePermission for each of these scope names.
This method is called by a
Wire object in response to the
Consumer service calling the
The Producer should coerce the value to be an instance of one of the
types specified by
. The types are specified in
order of of preference. The returned value should be as new or newer than
the last value furnished by this object.
Note: This method may be called by a
Wire object prior to this
object being notified that it is connected to that
If the Producer service returns an
Envelope object that has an
unpermitted scope name, then the Wire object must ignore (or remove) the
Wire object has a scope set, the return value must be an
Envelope objects (
object must have removed any
Envelope objects that have a scope
name that is not in the Wire object's scope.
Wireobject which is polling this service.
nullif the value cannot be coerced into a compatible type. Or an array of
Wireobjects to which this
Producerobject is connected.
This method is called when the Producer service is first registered and
subsequently whenever a
Wire associated with this Producer
becomes connected, is modified or becomes disconnected.
The Wire Admin service must call this method asynchronously. This implies that implementors of a Producer service can be assured that the callback will not take place during registration when they execute the registration in a synchronized method.
wiresAn array of the current and complete list of
Wireobjects to which this Producer service is connected. May be
nullif the Producer is not currently connected to any