    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
    015package org.apache.tapestry5.ioc.services;
    016
    017import org.slf4j.Logger;
    018
    019import 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 */
    038public 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}