| /* |
| * 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.commons.scxml; |
| |
| import java.io.Serializable; |
| import java.util.ArrayList; |
| import java.util.Arrays; |
| import java.util.HashMap; |
| import java.util.Iterator; |
| import java.util.List; |
| import java.util.Map; |
| |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| import org.apache.commons.scxml.model.Datamodel; |
| import org.apache.commons.scxml.model.History; |
| import org.apache.commons.scxml.model.ModelException; |
| import org.apache.commons.scxml.model.SCXML; |
| import org.apache.commons.scxml.model.State; |
| import org.apache.commons.scxml.model.Transition; |
| import org.apache.commons.scxml.model.TransitionTarget; |
| import org.apache.commons.scxml.semantics.SCXMLSemanticsImpl; |
| |
| /** |
| * <p>The SCXML "engine" that executes SCXML documents. The |
| * particular semantics used by this engine for executing the SCXML are |
| * encapsulated in the SCXMLSemantics implementation that it uses.</p> |
| * |
| * <p>The default implementation is |
| * <code>org.apache.commons.scxml.semantics.SCXMLSemanticsImpl</code></p> |
| * |
| * @see SCXMLSemantics |
| */ |
| public class SCXMLExecutor implements Serializable { |
| |
| /** |
| * Serial version UID. |
| */ |
| private static final long serialVersionUID = 1L; |
| |
| /** |
| * The Logger for the SCXMLExecutor. |
| */ |
| private Log log = LogFactory.getLog(SCXMLExecutor.class); |
| |
| /** |
| * The stateMachine being executed. |
| */ |
| private SCXML stateMachine; |
| |
| /** |
| * The current status of the stateMachine. |
| */ |
| private Status currentStatus; |
| |
| /** |
| * The event dispatcher to interface with external documents etc. |
| */ |
| private EventDispatcher eventdispatcher; |
| |
| /** |
| * The environment specific error reporter. |
| */ |
| private ErrorReporter errorReporter = null; |
| |
| /** |
| * Run-to-completion. |
| */ |
| private boolean superStep = true; |
| |
| /** |
| * Interpretation semantics. |
| */ |
| private SCXMLSemantics semantics; |
| |
| /** |
| * The SCInstance. |
| */ |
| private SCInstance scInstance; |
| |
| /** |
| * The worker method. |
| * Re-evaluates current status whenever any events are triggered. |
| * |
| * @param evts |
| * an array of external events which triggered during the last |
| * time quantum |
| * @throws ModelException in case there is a fatal SCXML object |
| * model problem. |
| */ |
| public synchronized void triggerEvents(final TriggerEvent[] evts) |
| throws ModelException { |
| // Set event data, saving old values |
| Object[] oldData = setEventData(evts); |
| |
| // Forward events (external only) to any existing invokes, |
| // and finalize processing |
| semantics.processInvokes(evts, errorReporter, scInstance); |
| |
| List evs = new ArrayList(Arrays.asList(evts)); |
| Step step = null; |
| |
| do { |
| // CreateStep |
| step = new Step(evs, currentStatus); |
| // EnumerateReachableTransitions |
| semantics.enumerateReachableTransitions(stateMachine, step, |
| errorReporter); |
| // FilterTransitionSet |
| semantics.filterTransitionsSet(step, eventdispatcher, |
| errorReporter, scInstance); |
| // FollowTransitions |
| semantics.followTransitions(step, errorReporter, scInstance); |
| // UpdateHistoryStates |
| semantics.updateHistoryStates(step, errorReporter, scInstance); |
| // ExecuteActions |
| semantics.executeActions(step, stateMachine, eventdispatcher, |
| errorReporter, scInstance); |
| // AssignCurrentStatus |
| updateStatus(step); |
| // ***Cleanup external events if superStep |
| if (superStep) { |
| evs.clear(); |
| } |
| } while (superStep && currentStatus.getEvents().size() > 0); |
| |
| // InitiateInvokes only after state machine has stabilized |
| semantics.initiateInvokes(step, errorReporter, scInstance); |
| |
| // Restore event data |
| restoreEventData(oldData); |
| logState(); |
| } |
| |
| /** |
| * Convenience method when only one event needs to be triggered. |
| * |
| * @param evt |
| * the external events which triggered during the last |
| * time quantum |
| * @throws ModelException in case there is a fatal SCXML object |
| * model problem. |
| */ |
| public void triggerEvent(final TriggerEvent evt) |
| throws ModelException { |
| triggerEvents(new TriggerEvent[] {evt}); |
| } |
| |
| /** |
| * Constructor. |
| * |
| * @param expEvaluator The expression evaluator |
| * @param evtDisp The event dispatcher |
| * @param errRep The error reporter |
| */ |
| public SCXMLExecutor(final Evaluator expEvaluator, |
| final EventDispatcher evtDisp, final ErrorReporter errRep) { |
| this(expEvaluator, evtDisp, errRep, null); |
| } |
| |
| /** |
| * Convenience constructor. |
| */ |
| public SCXMLExecutor() { |
| this(null, null, null, null); |
| } |
| |
| /** |
| * Constructor. |
| * |
| * @param expEvaluator The expression evaluator |
| * @param evtDisp The event dispatcher |
| * @param errRep The error reporter |
| * @param semantics The SCXML semantics |
| */ |
| public SCXMLExecutor(final Evaluator expEvaluator, |
| final EventDispatcher evtDisp, final ErrorReporter errRep, |
| final SCXMLSemantics semantics) { |
| this.eventdispatcher = evtDisp; |
| this.errorReporter = errRep; |
| this.currentStatus = new Status(); |
| this.stateMachine = null; |
| if (semantics == null) { |
| // Use default semantics, if none provided |
| this.semantics = new SCXMLSemanticsImpl(); |
| } else { |
| this.semantics = semantics; |
| } |
| this.scInstance = new SCInstance(this); |
| this.scInstance.setEvaluator(expEvaluator); |
| } |
| |
| /** |
| * Clear all state and begin from "initialstate" indicated |
| * on root SCXML element. |
| * |
| * @throws ModelException in case there is a fatal SCXML object |
| * model problem. |
| */ |
| public synchronized void reset() throws ModelException { |
| // Reset all variable contexts |
| Context rootCtx = scInstance.getRootContext(); |
| // Clone root datamodel |
| if (stateMachine == null) { |
| log.error(ERR_NO_STATE_MACHINE); |
| throw new ModelException(ERR_NO_STATE_MACHINE); |
| } else { |
| Datamodel rootdm = stateMachine.getDatamodel(); |
| SCXMLHelper.cloneDatamodel(rootdm, rootCtx, |
| scInstance.getEvaluator(), log); |
| } |
| // all states and parallels, only states have variable contexts |
| for (Iterator i = stateMachine.getTargets().values().iterator(); |
| i.hasNext();) { |
| TransitionTarget tt = (TransitionTarget) i.next(); |
| if (tt instanceof State) { |
| Context context = scInstance.lookupContext(tt); |
| if (context != null) { |
| context.reset(); |
| Datamodel dm = tt.getDatamodel(); |
| if (dm != null) { |
| SCXMLHelper.cloneDatamodel(dm, context, |
| scInstance.getEvaluator(), log); |
| } |
| } |
| } else if (tt instanceof History) { |
| scInstance.reset((History) tt); |
| } |
| } |
| // CreateEmptyStatus |
| currentStatus = new Status(); |
| Step step = new Step(null, currentStatus); |
| // DetermineInitialStates |
| semantics.determineInitialStates(stateMachine, |
| step.getAfterStatus().getStates(), |
| step.getEntryList(), errorReporter, scInstance); |
| // ExecuteActions |
| semantics.executeActions(step, stateMachine, eventdispatcher, |
| errorReporter, scInstance); |
| // AssignCurrentStatus |
| updateStatus(step); |
| // Execute Immediate Transitions |
| if (superStep && currentStatus.getEvents().size() > 0) { |
| this.triggerEvents(new TriggerEvent[0]); |
| } else { |
| // InitiateInvokes only after state machine has stabilized |
| semantics.initiateInvokes(step, errorReporter, scInstance); |
| logState(); |
| } |
| } |
| |
| /** |
| * Get the current status. |
| * |
| * @return The current Status |
| */ |
| public synchronized Status getCurrentStatus() { |
| return currentStatus; |
| } |
| |
| /** |
| * Set the expression evaluator. |
| * |
| * @param evaluator The evaluator to set. |
| */ |
| public void setEvaluator(final Evaluator evaluator) { |
| this.scInstance.setEvaluator(evaluator); |
| } |
| |
| /** |
| * Get the expression evaluator in use. |
| * |
| * @return Evaluator The evaluator in use. |
| */ |
| public Evaluator getEvaluator() { |
| return scInstance.getEvaluator(); |
| } |
| |
| /** |
| * Set the root context for this execution. |
| * |
| * @param rootContext The Context that ties to the host environment. |
| */ |
| public void setRootContext(final Context rootContext) { |
| this.scInstance.setRootContext(rootContext); |
| } |
| |
| /** |
| * Get the root context for this execution. |
| * |
| * @return Context The root context. |
| */ |
| public Context getRootContext() { |
| return scInstance.getRootContext(); |
| } |
| |
| /** |
| * Get the state machine that is being executed. |
| * |
| * @return Returns the stateMachine. |
| */ |
| public SCXML getStateMachine() { |
| return stateMachine; |
| } |
| |
| /** |
| * Set the state machine to be executed. |
| * |
| * @param stateMachine The stateMachine to set. |
| */ |
| public void setStateMachine(final SCXML stateMachine) { |
| // NormalizeStateMachine |
| SCXML sm = semantics.normalizeStateMachine(stateMachine, |
| errorReporter); |
| // StoreStateMachine |
| this.stateMachine = sm; |
| } |
| |
| /** |
| * Initiate state machine execution. |
| * |
| * @throws ModelException in case there is a fatal SCXML object |
| * model problem. |
| */ |
| public void go() throws ModelException { |
| // same as reset |
| this.reset(); |
| } |
| |
| /** |
| * Get the environment specific error reporter. |
| * |
| * @return Returns the errorReporter. |
| */ |
| public ErrorReporter getErrorReporter() { |
| return errorReporter; |
| } |
| |
| /** |
| * Set the environment specific error reporter. |
| * |
| * @param errorReporter The errorReporter to set. |
| */ |
| public void setErrorReporter(final ErrorReporter errorReporter) { |
| this.errorReporter = errorReporter; |
| } |
| |
| /** |
| * Get the event dispatcher. |
| * |
| * @return Returns the eventdispatcher. |
| */ |
| public EventDispatcher getEventdispatcher() { |
| return eventdispatcher; |
| } |
| |
| /** |
| * Set the event dispatcher. |
| * |
| * @param eventdispatcher The eventdispatcher to set. |
| */ |
| public void setEventdispatcher(final EventDispatcher eventdispatcher) { |
| this.eventdispatcher = eventdispatcher; |
| } |
| |
| /** |
| * Use "super-step", default is <code>true</code> |
| * (that is, run-to-completion is default). |
| * |
| * @return Returns the superStep property. |
| * @see #setSuperStep(boolean) |
| */ |
| public boolean isSuperStep() { |
| return superStep; |
| } |
| |
| /** |
| * Set the super step. |
| * |
| * @param superStep |
| * if true, the internal derived events are also processed |
| * (run-to-completion); |
| * if false, the internal derived events are stored in the |
| * CurrentStatus property and processed within the next |
| * triggerEvents() invocation, also the immediate (empty event) transitions |
| * are deferred until the next step |
| */ |
| public void setSuperStep(final boolean superStep) { |
| this.superStep = superStep; |
| } |
| |
| /** |
| * Add a listener to the document root. |
| * |
| * @param scxml The document root to attach listener to. |
| * @param listener The SCXMLListener. |
| */ |
| public void addListener(final SCXML scxml, final SCXMLListener listener) { |
| Object observable = scxml; |
| scInstance.getNotificationRegistry().addListener(observable, listener); |
| } |
| |
| /** |
| * Remove this listener from the document root. |
| * |
| * @param scxml The document root. |
| * @param listener The SCXMLListener to be removed. |
| */ |
| public void removeListener(final SCXML scxml, |
| final SCXMLListener listener) { |
| Object observable = scxml; |
| scInstance.getNotificationRegistry().removeListener(observable, |
| listener); |
| } |
| |
| /** |
| * Add a listener to this transition target. |
| * |
| * @param transitionTarget The <code>TransitionTarget</code> to |
| * attach listener to. |
| * @param listener The SCXMLListener. |
| */ |
| public void addListener(final TransitionTarget transitionTarget, |
| final SCXMLListener listener) { |
| Object observable = transitionTarget; |
| scInstance.getNotificationRegistry().addListener(observable, listener); |
| } |
| |
| /** |
| * Remove this listener for this transition target. |
| * |
| * @param transitionTarget The <code>TransitionTarget</code>. |
| * @param listener The SCXMLListener to be removed. |
| */ |
| public void removeListener(final TransitionTarget transitionTarget, |
| final SCXMLListener listener) { |
| Object observable = transitionTarget; |
| scInstance.getNotificationRegistry().removeListener(observable, |
| listener); |
| } |
| |
| /** |
| * Add a listener to this transition. |
| * |
| * @param transition The <code>Transition</code> to attach listener to. |
| * @param listener The SCXMLListener. |
| */ |
| public void addListener(final Transition transition, |
| final SCXMLListener listener) { |
| Object observable = transition; |
| scInstance.getNotificationRegistry().addListener(observable, listener); |
| } |
| |
| /** |
| * Remove this listener for this transition. |
| * |
| * @param transition The <code>Transition</code>. |
| * @param listener The SCXMLListener to be removed. |
| */ |
| public void removeListener(final Transition transition, |
| final SCXMLListener listener) { |
| Object observable = transition; |
| scInstance.getNotificationRegistry().removeListener(observable, |
| listener); |
| } |
| |
| /** |
| * Register an <code>Invoker</code> for this target type. |
| * |
| * @param targettype The target type (specified by "targettype" |
| * attribute of <invoke> tag). |
| * @param invokerClass The <code>Invoker</code> <code>Class</code>. |
| */ |
| public void registerInvokerClass(final String targettype, |
| final Class invokerClass) { |
| scInstance.registerInvokerClass(targettype, invokerClass); |
| } |
| |
| /** |
| * Remove the <code>Invoker</code> registered for this target |
| * type (if there is one registered). |
| * |
| * @param targettype The target type (specified by "targettype" |
| * attribute of <invoke> tag). |
| */ |
| public void unregisterInvokerClass(final String targettype) { |
| scInstance.unregisterInvokerClass(targettype); |
| } |
| |
| /** |
| * Get the state chart instance for this executor. |
| * |
| * @return The SCInstance for this executor. |
| */ |
| SCInstance getSCInstance() { |
| return scInstance; |
| } |
| |
| /** |
| * Log the current set of active states. |
| */ |
| private void logState() { |
| if (log.isDebugEnabled()) { |
| Iterator si = currentStatus.getStates().iterator(); |
| StringBuffer sb = new StringBuffer("Current States: ["); |
| while (si.hasNext()) { |
| State s = (State) si.next(); |
| sb.append(s.getId()); |
| if (si.hasNext()) { |
| sb.append(", "); |
| } |
| } |
| sb.append(']'); |
| log.debug(sb.toString()); |
| } |
| } |
| |
| /** |
| * @param step The most recent Step |
| */ |
| private void updateStatus(final Step step) { |
| currentStatus = step.getAfterStatus(); |
| scInstance.getRootContext().setLocal("_ALL_STATES", |
| SCXMLHelper.getAncestorClosure(currentStatus.getStates(), null)); |
| setEventData((TriggerEvent[]) currentStatus.getEvents(). |
| toArray(new TriggerEvent[0])); |
| } |
| |
| /** |
| * @param evts The events being triggered. |
| * @return Object[] Previous values. |
| */ |
| private Object[] setEventData(final TriggerEvent[] evts) { |
| Context rootCtx = scInstance.getRootContext(); |
| Object[] oldData = {rootCtx.get(EVENT_DATA), |
| rootCtx.get(EVENT_DATA_MAP)}; |
| int len = evts.length; |
| if (len > 0) { // 0 has retry semantics (eg: see usage in reset()) |
| Object eventData = null; |
| Map payloadMap = new HashMap(); |
| for (int i = 0; i < len; i++) { |
| TriggerEvent te = evts[i]; |
| payloadMap.put(te.getName(), te.getPayload()); |
| } |
| if (len == 1) { |
| // we have only one event |
| eventData = evts[0].getPayload(); |
| } |
| rootCtx.setLocal(EVENT_DATA, eventData); |
| rootCtx.setLocal(EVENT_DATA_MAP, payloadMap); |
| } |
| return oldData; |
| } |
| |
| /** |
| * @param oldData The old values to restore to. |
| */ |
| private void restoreEventData(final Object[] oldData) { |
| scInstance.getRootContext().setLocal(EVENT_DATA, oldData[0]); |
| scInstance.getRootContext().setLocal(EVENT_DATA_MAP, oldData[1]); |
| } |
| |
| /** |
| * The special variable for storing single event data / payload. |
| */ |
| private static final String EVENT_DATA = "_eventdata"; |
| |
| /** |
| * The special variable for storing event data / payload, |
| * when multiple events are triggered, keyed by event name. |
| */ |
| private static final String EVENT_DATA_MAP = "_eventdatamap"; |
| |
| /** |
| * SCXMLExecutor put into motion without setting a model (state machine). |
| */ |
| private static final String ERR_NO_STATE_MACHINE = |
| "SCXMLExecutor: State machine not set"; |
| |
| } |
| |