001    // Copyright 2006, 2007, 2011 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.services;
016    
017    import org.slf4j.Logger;
018    
019    import java.util.List;
020    
021    /**
022     * Creates a pipeline from a service interface and an ordered list of filters. Each filter is defined in terms of a
023     * filter interface: the filter interface is a variant of the service interface, where each method has an additional
024     * parameter that is an instance of the service interface. Typically, this service parameter (often named "delegate") is
025     * either the first or the last parameter of each method.
026     * <p/>
027     * The implementation of a filter method is expected to pass all of its parameters to the service instance passed into
028     * it.
029     * <p/>
030     * The interesting thing is that there may be multiple filters in the pipeline. A fabricated "bridge" object (that
031     * implements the service interface) is created to let each filter invoke methods on the next filter down the pipeline.
032     * This simplifies the model for creating pipelines, as each filter is coded as if it was directly "in front of" the
033     * terminator. In fact, it may be indirectly invoking methods on the next filter in the pipeline via a bridge instance.
034     * <p/>
035     * The builder is fairly smart about matching up service interface methods to filter interface methods, but keeping it
036     * simple is also a good idea.  By convention, the final parameter of each filter method is the delegate object (the bridge or terminator).
037     */
038    public interface PipelineBuilder
039    {
040        /**
041         * Creates a pipeline from the filters and a terminator.
042         *
043         * @param <S>              service type
044         * @param <F>              filter type
045         * @param logger           logs any warnings generated when constructing the pipeline
046         * @param serviceInterface defines the interface for the pipeline
047         * @param filterInterface  the filter interface, contributed into the pipeline
048         * @param filters          sorted list of filters
049         * @param terminator       end of the pipeline
050         * @return an object that encapsulates the filters and the terminator
051         */
052        <S, F> S build(Logger logger, Class<S> serviceInterface, Class<F> filterInterface, List<F> filters, S terminator);
053    
054        /**
055         * Creates a pipeline from just the filters. A {@link DefaultImplementationBuilder default implementation} is
056         * created as the terminator.
057         *
058         * @param <S>              service type
059         * @param <F>              filter type
060         * @param logger           logs any warnings generated when constructing the pipeline
061         * @param serviceInterface defines the interface for the pipeline
062         * @param filterInterface  the filter interface, contributed into the pipeline
063         * @param filters          sorted list of filters
064         * @return an object that encapsulates the filters and the default implementation
065         */
066        <S, F> S build(Logger logger, Class<S> serviceInterface, Class<F> filterInterface, List<F> filters);
067    
068    }