001/**
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.camel.spi;
018
019import java.util.function.Predicate;
020
021import org.apache.camel.AsyncCallback;
022import org.apache.camel.Exchange;
023import org.apache.camel.Message;
024import org.apache.camel.Processor;
025import org.apache.camel.Route;
026import org.apache.camel.Service;
027
028/**
029 * An object representing the unit of work processing an {@link Exchange}
030 * which allows the use of {@link Synchronization} hooks. This object might map one-to-one with
031 * a transaction in JPA or Spring; or might not.
032 */
033public interface UnitOfWork extends Service {
034
035    /**
036     * Adds a synchronization hook
037     *
038     * @param synchronization the hook
039     */
040    void addSynchronization(Synchronization synchronization);
041
042    /**
043     * Removes a synchronization hook
044     *
045     * @param synchronization the hook
046     */
047    void removeSynchronization(Synchronization synchronization);
048
049    /**
050     * Checks if the passed synchronization hook is already part of this unit of work.
051     *
052     * @param synchronization the hook
053     * @return <tt>true</tt>, if the passed synchronization is part of this unit of work, else <tt>false</tt>
054     */
055    boolean containsSynchronization(Synchronization synchronization);
056
057    /**
058     * Handover all the registered synchronizations to the target {@link org.apache.camel.Exchange}.
059     * <p/>
060     * This is used when a route turns into asynchronous and the {@link org.apache.camel.Exchange} that
061     * is continued and routed in the async thread should do the on completion callbacks instead of the
062     * original synchronous thread.
063     *
064     * @param target the target exchange
065     */
066    void handoverSynchronization(Exchange target);
067
068    /**
069     * Handover all the registered synchronizations to the target {@link org.apache.camel.Exchange}.
070     * <p/>
071     * This is used when a route turns into asynchronous and the {@link org.apache.camel.Exchange} that
072     * is continued and routed in the async thread should do the on completion callbacks instead of the
073     * original synchronous thread.
074     *
075     * @param target the target exchange
076     * @param filter optional filter to only handover if filter returns <tt>true</tt>
077     */
078    void handoverSynchronization(Exchange target, Predicate<Synchronization> filter);
079
080    /**
081     * Invoked when this unit of work has been completed, whether it has failed or completed
082     *
083     * @param exchange the current exchange
084     */
085    void done(Exchange exchange);
086
087    /**
088     * Invoked when this unit of work is about to be routed by the given route.
089     *
090     * @param exchange the current exchange
091     * @param route    the route
092     */
093    void beforeRoute(Exchange exchange, Route route);
094
095    /**
096     * Invoked when this unit of work is done being routed by the given route.
097     *
098     * @param exchange the current exchange
099     * @param route    the route
100     */
101    void afterRoute(Exchange exchange, Route route);
102
103    /**
104     * Returns the unique ID of this unit of work, lazily creating one if it does not yet have one
105     *
106     * @return the unique ID
107     */
108    String getId();
109
110    /**
111     * Gets the original IN {@link Message} this Unit of Work was started with.
112     * <p/>
113     * The original message is only returned if the option {@link org.apache.camel.RuntimeConfiguration#isAllowUseOriginalMessage()}
114     * is enabled. If its disabled, then <tt>null</tt> is returned.
115     *
116     * @return the original IN {@link Message}, or <tt>null</tt> if using original message is disabled.
117     */
118    Message getOriginalInMessage();
119
120    /**
121     * Gets tracing information
122     *
123     * @return trace information
124     */
125    TracedRouteNodes getTracedRouteNodes();
126
127    /**
128     * Are we transacted?
129     *
130     * @return <tt>true</tt> if transacted, <tt>false</tt> otherwise
131     */
132    boolean isTransacted();
133
134    /**
135     * Are we already transacted by the given transaction key?
136     *
137     * @param key the transaction key
138     * @return <tt>true</tt> if already, <tt>false</tt> otherwise
139     */
140    boolean isTransactedBy(Object key);
141
142    /**
143     * Mark this UnitOfWork as being transacted by the given transaction key.
144     * <p/>
145     * When the transaction is completed then invoke the {@link #endTransactedBy(Object)} method using the same key.
146     *
147     * @param key the transaction key
148     */
149    void beginTransactedBy(Object key);
150
151    /**
152     * Mark this UnitOfWork as not transacted anymore by the given transaction definition.
153     *
154     * @param key the transaction key
155     */
156    void endTransactedBy(Object key);
157
158    /**
159     * Gets the {@link RouteContext} that this {@link UnitOfWork} currently is being routed through.
160     * <p/>
161     * Notice that an {@link Exchange} can be routed through multiple routes and thus the
162     * {@link org.apache.camel.spi.RouteContext} can change over time.
163     *
164     * @return the route context
165     * @see #pushRouteContext(RouteContext)
166     * @see #popRouteContext()
167     */
168    RouteContext getRouteContext();
169
170    /**
171     * Pushes the {@link RouteContext} that this {@link UnitOfWork} currently is being routed through.
172     * <p/>
173     * Notice that an {@link Exchange} can be routed through multiple routes and thus the
174     * {@link org.apache.camel.spi.RouteContext} can change over time.
175     *
176     * @param routeContext the route context
177     */
178    void pushRouteContext(RouteContext routeContext);
179
180    /**
181     * When finished being routed under the current {@link org.apache.camel.spi.RouteContext}
182     * it should be removed.
183     *
184     * @return the route context or <tt>null</tt> if none existed
185     */
186    RouteContext popRouteContext();
187
188    /**
189     * Strategy for optional work to be execute before processing
190     * <p/>
191     * For example the {@link org.apache.camel.impl.MDCUnitOfWork} leverages this
192     * to ensure MDC is handled correctly during routing exchanges using the
193     * asynchronous routing engine.
194     *
195     * @param processor the processor to be executed
196     * @param exchange  the current exchange
197     * @param callback  the callback
198     * @return the callback to be used (can return a wrapped callback)
199     */
200    AsyncCallback beforeProcess(Processor processor, Exchange exchange, AsyncCallback callback);
201
202    /**
203     * Strategy for optional work to be executed after the processing
204     *
205     * @param processor the processor executed
206     * @param exchange  the current exchange
207     * @param callback  the callback used
208     * @param doneSync  whether the process was done synchronously or asynchronously
209     */
210    void afterProcess(Processor processor, Exchange exchange, AsyncCallback callback, boolean doneSync);
211
212    /**
213     * Create a child unit of work, which is associated to this unit of work as its parent.
214     * <p/>
215     * This is often used when EIPs need to support {@link SubUnitOfWork}s. For example a splitter,
216     * where the sub messages of the splitter all participate in the same sub unit of work.
217     * That sub unit of work then decides whether the Splitter (in general) is failed or a
218     * processed successfully.
219     *
220     * @param childExchange the child exchange
221     * @return the created child unit of work
222     * @see SubUnitOfWork
223     * @see SubUnitOfWorkCallback
224     */
225    UnitOfWork createChildUnitOfWork(Exchange childExchange);
226
227    /**
228     * Sets the parent unit of work.
229     *
230     * @param parentUnitOfWork the parent
231     */
232    void setParentUnitOfWork(UnitOfWork parentUnitOfWork);
233
234    /**
235     * Gets the {@link SubUnitOfWorkCallback} if this unit of work participates in a sub unit of work.
236     *
237     * @return the callback, or <tt>null</tt> if this unit of work is not part of a sub unit of work.
238     * @see #beginSubUnitOfWork(org.apache.camel.Exchange)
239     */
240    SubUnitOfWorkCallback getSubUnitOfWorkCallback();
241
242    /**
243     * Begins a {@link SubUnitOfWork}, where sub (child) unit of works participate in a parent unit of work.
244     * The {@link SubUnitOfWork} will callback to the parent unit of work using {@link SubUnitOfWorkCallback}s.
245     *
246     * @param exchange the exchange
247     */
248    void beginSubUnitOfWork(Exchange exchange);
249
250    /**
251     * Ends a {@link SubUnitOfWork}.
252     * <p/>
253     * The {@link #beginSubUnitOfWork(org.apache.camel.Exchange)} must have been invoked
254     * prior to this operation.
255     *
256     * @param exchange the exchange
257     */
258    void endSubUnitOfWork(Exchange exchange);
259
260}