Author: niclas
Date: Fri Jul 30 02:46:40 2004
New Revision: 30982
Added:
avalon/trunk/runtime/framework/api/src/java/org/apache/avalon/framework/availability/
avalon/trunk/runtime/framework/api/src/java/org/apache/avalon/framework/availability/AvailabilityAware.java (contents, props changed)
avalon/trunk/runtime/framework/api/src/java/org/apache/avalon/framework/availability/UnavailableException.java (contents, props changed)
Log:
Proposal for a new AvailabilityAware interface in Framework. The change is AFAICT 100% compatible with existing components, existing containers, and even new AvailabilityAware components running in old containers.
Added: avalon/trunk/runtime/framework/api/src/java/org/apache/avalon/framework/availability/AvailabilityAware.java
==============================================================================
--- (empty file)
+++ avalon/trunk/runtime/framework/api/src/java/org/apache/avalon/framework/availability/AvailabilityAware.java Fri Jul 30 02:46:40 2004
@@ -0,0 +1,71 @@
+/*
+ * Copyright 1997-2004 The Apache Software Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.avalon.framework.availability;
+
+
+/** An Availability contract between the container and the component.
+ *
+ * <p>A component that implements AvailabilityAware, is capable to be notified
+ * that components that it has previously looked up via the
+ * ServiceManager.lookup() method are made available and non-available,
+ * and can gracefully handle unavailability.</p>
+ *
+ * <p>Containers are only required to support this interface, if the
+ * container supports dynamic loading/unloading of components, hot-deploys,
+ * remote components and similar cases where components may disappear for
+ * a shorter or longer period of time.</p>
+ *
+ * @since 4.5
+ *
+ * @author <a href="mailto:[email protected]">Avalon Development Team</a>
+ * @version $Id$
+ */
+public interface AvailabilityAware
+{
+ /** Notification that component is available.
+ * <p>The component that previously has been looked up in the
+ * ServiceManager, using <i>key</i> is now available. This method can
+ * either be called after the componentUnavailable() method signalled that
+ * a component is no longer available, OR if the ServiceManager.lookup()
+ * returned a null (optional lookup) indicating that the requested
+ * component didn't exist.</p>
+ * <p>
+ * This method will NOT be called with a <i>key</i> argument that has
+ * not been used in a ServiceManager.lookup() previously.
+ * </p>
+ *
+ * @param key The key that was used to lookup the component in the
+ * ServiceManager earlier.
+ */
+ void componentAvailable( String key );
+
+ /** Notification that component is no longer available.
+ * <p>The component that previously has been looked up in the
+ * ServiceManager, using <i>key</i> is no longer available. The container
+ * does not place any restrictions on how long the component will be
+ * unavailble, and the AvailabilityAware component, must employ one or more
+ * strategies on how to gracefully handle short and long absences of
+ * dependent components. </p>
+ * <p>
+ * This method will NOT be called with a <i>key</i> argument that has
+ * not been used in a ServiceManager.lookup() previously.
+ * </p>
+ *
+ * @param key The key that was used to lookup the component in the
+ * ServiceManager earlier.
+ */
+ void componentUnavailble( String key );
+}
Added: avalon/trunk/runtime/framework/api/src/java/org/apache/avalon/framework/availability/UnavailableException.java
==============================================================================
--- (empty file)
+++ avalon/trunk/runtime/framework/api/src/java/org/apache/avalon/framework/availability/UnavailableException.java Fri Jul 30 02:46:40 2004
@@ -0,0 +1,52 @@
+/*
+ * Copyright 1997-2004 The Apache Software Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.avalon.framework.availability;
+
+/** Exception to signal component is not available.
+ *
+ * UnavailableException is thrown in any method to another component,
+ * but only if the caller implements AvailabilityAware.
+ *
+ * @since 4.5
+ *
+ * @author <a href="mailto:[email protected]">Avalon Development Team</a>
+ * @version $Id$
+ */
+public class UnavailableException extends RuntimeException
+{
+ private String m_Key;
+
+ /** Constructor.
+ * @param message The non-localized message to be embedded into the
+ * exception.
+ *
+ * @param key The key that the caller used to lookup the component
+ * with.
+ */
+ public UnavailableException( String message, String key )
+ {
+ super( message );
+ m_Key = key;
+ }
+
+ /** Returns the key to the component that is no longer available.
+ *
+ */
+ public String getLookupKey()
+ {
+ return m_Key;
+ }
+}
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