Michael E. Rodriguez | 86f57b0 | 2006-03-29 21:05:08 +0000 | [diff] [blame] | 1 | /* |
Richard S. Hall | 33b07d1 | 2006-10-18 22:02:38 +0000 | [diff] [blame^] | 2 | * $Header: /cvshome/build/org.osgi.service.wireadmin/src/org/osgi/service/wireadmin/Consumer.java,v 1.10 2006/07/11 00:54:10 hargrave Exp $ |
Michael E. Rodriguez | 86f57b0 | 2006-03-29 21:05:08 +0000 | [diff] [blame] | 3 | * |
Richard S. Hall | 33b07d1 | 2006-10-18 22:02:38 +0000 | [diff] [blame^] | 4 | * Copyright (c) OSGi Alliance (2002, 2006). All Rights Reserved. |
Michael E. Rodriguez | 86f57b0 | 2006-03-29 21:05:08 +0000 | [diff] [blame] | 5 | * |
| 6 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 7 | * you may not use this file except in compliance with the License. |
| 8 | * You may obtain a copy of the License at |
| 9 | * |
| 10 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 11 | * |
| 12 | * Unless required by applicable law or agreed to in writing, software |
| 13 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 14 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 15 | * See the License for the specific language governing permissions and |
| 16 | * limitations under the License. |
| 17 | */ |
| 18 | package org.osgi.service.wireadmin; |
| 19 | |
| 20 | /** |
| 21 | * Data Consumer, a service that can receive udpated values from |
Richard S. Hall | 33b07d1 | 2006-10-18 22:02:38 +0000 | [diff] [blame^] | 22 | * {@link Producer} services. |
Michael E. Rodriguez | 86f57b0 | 2006-03-29 21:05:08 +0000 | [diff] [blame] | 23 | * |
| 24 | * <p> |
| 25 | * Service objects registered under the <code>Consumer</code> interface are |
| 26 | * expected to consume values from a Producer service via a <code>Wire</code> |
| 27 | * object. A Consumer service may poll the Producer service by calling the |
Richard S. Hall | 33b07d1 | 2006-10-18 22:02:38 +0000 | [diff] [blame^] | 28 | * {@link Wire#poll} method. The Consumer service will also receive an updated |
| 29 | * value when called at it's {@link #updated} method. The Producer service |
Michael E. Rodriguez | 86f57b0 | 2006-03-29 21:05:08 +0000 | [diff] [blame] | 30 | * should have coerced the value to be an instance of one of the types specified |
Richard S. Hall | 33b07d1 | 2006-10-18 22:02:38 +0000 | [diff] [blame^] | 31 | * by the {@link Wire#getFlavors} method, or one of their subclasses. |
Michael E. Rodriguez | 86f57b0 | 2006-03-29 21:05:08 +0000 | [diff] [blame] | 32 | * |
| 33 | * <p> |
| 34 | * Consumer service objects must register with a <code>service.pid</code> and a |
Richard S. Hall | 33b07d1 | 2006-10-18 22:02:38 +0000 | [diff] [blame^] | 35 | * {@link WireConstants#WIREADMIN_CONSUMER_FLAVORS} property. It is recommended |
Michael E. Rodriguez | 86f57b0 | 2006-03-29 21:05:08 +0000 | [diff] [blame] | 36 | * that Consumer service objects also register with a |
| 37 | * <code>service.description</code> property. |
| 38 | * |
| 39 | * <p> |
| 40 | * If an <code>Exception</code> is thrown by any of the <code>Consumer</code> |
| 41 | * methods, a <code>WireAdminEvent</code> of type |
Richard S. Hall | 33b07d1 | 2006-10-18 22:02:38 +0000 | [diff] [blame^] | 42 | * {@link WireAdminEvent#CONSUMER_EXCEPTION} is broadcast by the Wire Admin |
Michael E. Rodriguez | 86f57b0 | 2006-03-29 21:05:08 +0000 | [diff] [blame] | 43 | * service. |
| 44 | * |
| 45 | * <p> |
| 46 | * Security Considerations - Data consuming bundles will require |
| 47 | * <code>ServicePermission[Consumer,REGISTER]</code>. In general, only the Wire |
| 48 | * Admin service bundle should have this permission. Thus only the Wire Admin |
| 49 | * service may directly call a Consumer service. Care must be taken in the |
| 50 | * sharing of <code>Wire</code> objects with other bundles. |
| 51 | * <p> |
| 52 | * Consumer services must be registered with their scope when they can receive |
| 53 | * different types of objects from the Producer service. The Consumer service |
| 54 | * should have <code>WirePermission</code> for each of these scope names. |
| 55 | * |
Richard S. Hall | 33b07d1 | 2006-10-18 22:02:38 +0000 | [diff] [blame^] | 56 | * @version $Revision: 1.10 $ |
Michael E. Rodriguez | 86f57b0 | 2006-03-29 21:05:08 +0000 | [diff] [blame] | 57 | */ |
| 58 | public interface Consumer { |
| 59 | /** |
| 60 | * Update the value. This Consumer service is called by the <code>Wire</code> |
| 61 | * object with an updated value from the Producer service. |
| 62 | * |
| 63 | * <p> |
| 64 | * Note: This method may be called by a <code>Wire</code> object prior to this |
| 65 | * object being notified that it is connected to that <code>Wire</code> object |
Richard S. Hall | 33b07d1 | 2006-10-18 22:02:38 +0000 | [diff] [blame^] | 66 | * (via the {@link #producersConnected} method). |
Michael E. Rodriguez | 86f57b0 | 2006-03-29 21:05:08 +0000 | [diff] [blame] | 67 | * <p> |
| 68 | * When the Consumer service can receive <code>Envelope</code> objects, it |
| 69 | * must have registered all scope names together with the service object, |
| 70 | * and each of those names must be permitted by the bundle's |
| 71 | * <code>WirePermission</code>. If an <code>Envelope</code> object is delivered |
| 72 | * with the <code>updated</code> method, then the Consumer service should |
| 73 | * assume that the security check has been performed. |
| 74 | * |
| 75 | * @param wire The <code>Wire</code> object which is delivering the updated |
| 76 | * value. |
| 77 | * @param value The updated value. The value should be an instance of one of |
Richard S. Hall | 33b07d1 | 2006-10-18 22:02:38 +0000 | [diff] [blame^] | 78 | * the types specified by the {@link Wire#getFlavors} method. |
Michael E. Rodriguez | 86f57b0 | 2006-03-29 21:05:08 +0000 | [diff] [blame] | 79 | */ |
| 80 | public void updated(Wire wire, Object value); |
| 81 | |
| 82 | /** |
| 83 | * Update the list of <code>Wire</code> objects to which this Consumer service |
| 84 | * is connected. |
| 85 | * |
| 86 | * <p> |
| 87 | * This method is called when the Consumer service is first registered and |
| 88 | * subsequently whenever a <code>Wire</code> associated with this Consumer |
| 89 | * service becomes connected, is modified or becomes disconnected. |
| 90 | * |
| 91 | * <p> |
| 92 | * The Wire Admin service must call this method asynchronously. This implies |
| 93 | * that implementors of Consumer can be assured that the callback will not |
| 94 | * take place during registration when they execute the registration in a |
| 95 | * synchronized method. |
| 96 | * |
| 97 | * @param wires An array of the current and complete list of <code>Wire</code> |
| 98 | * objects to which this Consumer service is connected. May be |
| 99 | * <code>null</code> if the Consumer service is not currently connected |
| 100 | * to any <code>Wire</code> objects. |
| 101 | */ |
| 102 | public void producersConnected(Wire[] wires); |
| 103 | } |