| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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.uima.flow; |
| |
| |
| import org.apache.uima.analysis_engine.AnalysisEngineProcessException; |
| import org.apache.uima.cas.AbstractCas; |
| |
| /** |
| * A Flow object is responsible for routing a single CAS through an Aggregate Analysis Engine. |
| * <p> |
| * Typically, developers extend {@link org.apache.uima.flow.CasFlow_ImplBase} or |
| * {@link org.apache.uima.flow.JCasFlow_ImplBase} depending on which CAS interface they wish to use. |
| */ |
| public interface Flow { |
| /** |
| * Gets the next destination for the CAS. This is defined by a {@link Step} object. There may be |
| * different kinds of Step objects to indicate different kinds of routing actions. |
| * |
| * @return the next destination for the CAS |
| * @throws AnalysisEngineProcessException |
| * if a failure occurs while determining the next destination |
| */ |
| Step next() throws AnalysisEngineProcessException; |
| |
| /** |
| * Called by the framework if the CAS that is being routed by this Flow has been sent to a CAS |
| * Multiplier which has then created a new CAS derived from that original CAS. |
| * <p> |
| * It is not required for a Flow implementation to support the production of new CASes in the |
| * middle of the flow, in which case this method may throw an exception. |
| * <p> |
| * If implemented, this method should construct a new {@link Flow} object that will be used to |
| * route the new CAS. The new Flow object then takes over all responsibility for that CAS. |
| * |
| * @param newCas |
| * the new CAS |
| * @param producedBy |
| * key of the AnalysisEngine (CAS Multiplier) that produced the new CAS |
| * |
| * @return a new Flow object that has responsibility for routing <code>aCAS</code> through the |
| * Aggregate Analysis Engine. |
| * |
| * @throws AnalysisEngineProcessException |
| */ |
| Flow newCasProduced(AbstractCas newCas, String producedBy) throws AnalysisEngineProcessException; |
| |
| /** |
| * May be called by the framework to ask the FlowController if processing of the CAS can |
| * continue after a failure occurred while executing the last Step that the Flow Controller |
| * returned. |
| * <p> |
| * If this method returns true, then the framework may continue to call the {@link #next()} method |
| * to continue routing the CAS. If this method returns false, the framework will not make any |
| * more calls to the {@link #next()} method, and will call the {@link #aborted()} method. |
| * <p> |
| * In the case where the last Step was a {@link ParallelStep}, if at least one of the destinations |
| * resulted in a failure, this method will be called to report one of the failures. If this method |
| * returns true, but one of the other destinations in the ParallelStep resulted in a failure, this |
| * method will be called again to report the next failure. This continues until either this method |
| * returns false or there are no more failures. |
| * <p> |
| * Note that it is possible for processing of a CAS to be aborted without this method being called. |
| * This method is only called when an attempt is being made to continue processing of the CAS |
| * following an error, which may be an application configuration decision. |
| * |
| * @param failedAeKey The key of the analysis engine that failed. |
| * @param failure the Exception that occurred |
| * |
| * @return true if the FlowController decides that processing of the CAS can continue; false if |
| * processing of the CAS should be aborted. |
| */ |
| boolean continueOnFailure(String failedAeKey, Exception failure); |
| |
| /** |
| * Called by the framework if processing has been aborted for the CAS that was being |
| * routed by this Flow object. No further processing will take place on the CAS after |
| * this method is called, so the framework will not call the {@link #next()} method again. |
| * <p> |
| * This method provides the Flow object with an opportunity to clean up any resources. |
| * Also, it could be used to allow the FlowController to reuse a Flow object if desired. |
| */ |
| void aborted(); |
| |
| } |