001    // Copyright 2006, 2007, 2008, 2009 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry5.ioc.annotations;
016    
017    import org.apache.tapestry5.ioc.ServiceBinder;
018    import org.apache.tapestry5.ioc.ServiceLifecycle;
019    import org.apache.tapestry5.ioc.services.ServiceLifecycleSource;
020    
021    import java.lang.annotation.Documented;
022    import static java.lang.annotation.ElementType.METHOD;
023    import static java.lang.annotation.ElementType.TYPE;
024    import java.lang.annotation.Retention;
025    import static java.lang.annotation.RetentionPolicy.RUNTIME;
026    import java.lang.annotation.Target;
027    
028    /**
029     * An optional annotation that may be placed on a service building method of a module, or on the implementation class
030     * (when using service binding). The annotation overrides the default scope for services (the default being a global
031     * singleton that is instantiated on demand) for an alternate lifecycle. Alternate lifecycles are typically used to bind
032     * a service implementation to a single thread or request. Modules may define new scopes. Each scope should have a
033     * corresponding {@link ServiceLifecycle} implementation. The linkage from scope name to service lifecycle occurs via a
034     * contribution to the {@link ServiceLifecycleSource} service configuration.
035     * <p/>
036     * The annotation may also be placed directly on a service implementation class, when using service binding (via
037     * the {@link ServiceBinder}).
038     *
039     * @see org.apache.tapestry5.ioc.ScopeConstants
040     */
041    @Target(
042            {TYPE, METHOD})
043    @Retention(RUNTIME)
044    @Documented
045    @UseWith({AnnotationUseContext.SERVICE, AnnotationUseContext.MODULE})
046    public @interface Scope
047    {
048        /**
049         * An identifier used to look up a non-default {@link ServiceLifecycle}.
050         */
051        String value();
052    }