2 * Copyright 2007 the original author or authors.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
16 package org.wamblee.system.core;
18 import java.util.ArrayList;
19 import java.util.Arrays;
20 import java.util.Collection;
21 import java.util.HashSet;
22 import java.util.Iterator;
23 import java.util.List;
26 import org.apache.commons.logging.Log;
27 import org.apache.commons.logging.LogFactory;
30 * Container consisting of multiple components.
32 * @author Erik Brakkee
34 public class Container extends AbstractComponent<Scope> {
36 private static final Log LOG = LogFactory.getLog(Container.class);
38 private List<Component> _components;
39 private Set<String> _componentNames;
40 private boolean _sealed;
42 public static RequiredInterface[] filterRequiredServices(
43 ProvidedInterface aProvided,
44 Collection<RequiredInterface> aDescriptors) {
45 List<RequiredInterface> required = new ArrayList<RequiredInterface>();
46 for (RequiredInterface descriptor : aDescriptors) {
47 if (descriptor.implementedBy(aProvided)) {
48 required.add(descriptor);
51 return required.toArray(new RequiredInterface[0]);
54 public static ProvidedInterface[] filterProvidedServices(
55 RequiredInterface aRequired, Collection<ProvidedInterface> aProvided) {
56 List<ProvidedInterface> provided = new ArrayList<ProvidedInterface>();
57 for (ProvidedInterface descriptor : aProvided) {
58 if (aRequired.implementedBy(descriptor)) {
59 provided.add(descriptor);
62 return provided.toArray(new ProvidedInterface[0]);
66 * Constructs the container
69 * Name of the container
73 * Provided services of the container
75 * Required services by the container.
77 public Container(String aName, Component[] aComponents,
78 ProvidedInterface[] aProvided, RequiredInterface[] aRequired) {
79 super(aName, aProvided, aRequired);
80 _components = new ArrayList<Component>();
82 _componentNames = new HashSet<String>();
84 for (Component component : aComponents) {
85 addComponent(component);
89 public Container(String aName) {
90 this(aName, new Component[0], new ProvidedInterface[0],
91 new RequiredInterface[0]);
94 public Container addComponent(Component aComponent) {
96 if (aComponent.getContext() != null) {
97 throw new SystemAssemblyException(
98 "Inconsistent hierarchy, component '"
99 + aComponent.getName()
100 + "' is already part of another hierarchy");
102 if (_componentNames.contains(aComponent.getName())) {
103 throw new SystemAssemblyException("Duplicate component '"
104 + aComponent.getName() + "'");
106 _components.add(aComponent);
107 _componentNames.add(aComponent.getName());
108 aComponent.addContext(getQualifiedName());
113 public Container addProvidedInterface(ProvidedInterface aProvided) {
115 super.addProvidedInterface(aProvided);
120 public Container addRequiredInterface(RequiredInterface aRequired) {
122 super.addRequiredInterface(aRequired);
127 * Validates the components together to check that there are no required
128 * services not in the required list and no services in the provided list
129 * that cannot be provided. Also logs a warning in case of superfluous
132 * @throws SystemAssemblyException
133 * in case of any validation problems.
135 public void validate() {
136 List<ProvidedInterface> provided = new ArrayList<ProvidedInterface>();
137 for (Component component : _components) {
138 provided.addAll(Arrays.asList(component.getProvidedInterfaces()));
141 List<RequiredInterface> required = new ArrayList<RequiredInterface>();
142 for (Component component : _components) {
143 required.addAll(Arrays.asList(component.getRequiredInterfaces()));
146 validateProvidedInterfacesArePresent(provided);
148 validateRequiredInterfaces(required);
150 doStartOptionalDryRun(null, true);
153 private void validateRequiredInterfaces(List<RequiredInterface> aRequired) {
154 for (RequiredInterface service : getRequiredInterfaces()) {
155 // TODO required interfaces by the component could be
156 // subclasses or implementations of the requirements
157 // of the contained components. The code below assumes
159 if (!(aRequired.contains(service))) {
162 + "' indicated as required is not actually required by any of the components");
164 // Check for the case that the externally required service
165 // is optional whereas the internally required service is
167 if (service.isOptional()) {
168 for (RequiredInterface intf : aRequired) {
169 if (intf.equals(service) && !intf.isOptional()) {
170 warn("Required service '"
172 + "' indicated as optional is mandatory by one of its components ("
176 + "), this can lead to problems when the container is started and the interface is not provided to the container.");
183 private void validateProvidedInterfacesArePresent(
184 List<ProvidedInterface> aProvided) {
185 for (ProvidedInterface service : getProvidedInterfaces()) {
186 // TODO provided interfaces by components could be
187 // provide subclasses or implementations of the
188 // provided interfaces of the container.
189 // The code below assumes an exact match.
190 if (!(aProvided.contains(service))) {
191 throw new SystemAssemblyException(getName() + ": Service '"
193 + "' is not provided by any of its components");
199 * Starts the container. After the container is started, the container
200 * becomes sealed meaning that no further components, required or provided
201 * interfaces may be added.
205 public Scope start() {
208 Scope scope = super.start(new DefaultScope(new ProvidedInterface[0]));
214 * Seal the container, meaning that no further components or interfaces may
222 * Checks if the container is sealed.
224 * @return True iff the container is sealed.
226 public boolean isSealed() {
231 protected Scope doStart(Scope aExternalScope) {
232 return doStartOptionalDryRun(aExternalScope, false);
235 private Scope doStartOptionalDryRun(Scope aExternalScope, boolean aDryRun) {
236 LOG.info("Starting '" + getQualifiedName() + "'");
238 Scope scope = new DefaultScope(getProvidedInterfaces(), aExternalScope);
240 List<ProvidedInterface> allProvided = new ArrayList<ProvidedInterface>();
242 addProvidersOfRequiredInterfaces(allProvided);
244 List<Component> started = new ArrayList<Component>();
245 for (Component component : _components) {
247 initializeProvidersForRequiredInterfaces(allProvided,
250 // Start the service.
252 Object runtime = component.start(scope);
253 scope.addRuntime(component, runtime);
254 started.add(component);
257 // add all provided services
258 ProvidedInterface[] provided = component
259 .getProvidedInterfaces();
260 allProvided.addAll(Arrays.asList(provided));
261 } catch (SystemAssemblyException e) {
263 } catch (RuntimeException e) {
264 LOG.error(getQualifiedName() + ": could not start '"
265 + component.getQualifiedName() + "'", e);
266 stopAlreadyStartedComponents(started, scope);
273 private void addProvidersOfRequiredInterfaces(
274 List<ProvidedInterface> allProvided) {
275 // all interfaces from the required list of this container are
276 // provided to the components inside it.
277 RequiredInterface[] required = getRequiredInterfaces();
278 for (RequiredInterface intf : required) {
279 ProvidedInterface provider = intf.getProvider();
280 if (provider != null) {
281 allProvided.add(provider);
283 if (!intf.isOptional()) {
284 throw new SystemAssemblyException(getQualifiedName()
285 + ": required interface '" + intf
286 + "' is not provided");
292 private void stopAlreadyStartedComponents(List<Component> aStarted,
294 // an exception occurred, stop the successfully started
296 for (int i = aStarted.size() - 1; i >= 0; i--) {
298 Component component = aStarted.get(i);
299 aStarted.get(i).stop(aScope.getRuntime(component));
300 } catch (Throwable t) {
301 LOG.error(getQualifiedName() + ": error stopping "
302 + aStarted.get(i).getQualifiedName());
308 * Sets the provided interface or a component.
310 * @param aAllProvided
311 * All available provided interfaces.
313 * Component whose required interfaces we are looking at.
314 * @param aValidateOnly
315 * If true then the provider will not be set for required
318 private void initializeProvidersForRequiredInterfaces(
319 List<ProvidedInterface> aAllProvided, Component aComponent,
320 boolean aValidateOnly) {
321 // Check if all required services are already provided by
325 for (RequiredInterface descriptor : aComponent.getRequiredInterfaces()) {
326 ProvidedInterface[] filtered = filterProvidedServices(descriptor,
328 if (filtered.length == 1) {
329 if (!aValidateOnly) {
330 descriptor.setProvider(filtered[0]);
332 } else if (filtered.length > 1) {
333 throw new SystemAssemblyException(
336 + "' required by system '"
338 + "' matches multiple services provided by other systems: "
339 + getServers(filtered));
341 // filtered.length == 0
342 if (!descriptor.isOptional()) {
343 throw new SystemAssemblyException(
346 + "' required by system '"
348 + "' is not provided by systems that are started earlier");
355 protected void doStop(Scope aScope) {
356 for (int i = _components.size() - 1; i >= 0; i--) {
357 Component component = _components.get(i);
358 Object runtime = aScope.getRuntime(component);
359 component.stop(runtime);
363 private void info(String aMsg) {
364 LOG.info(getQualifiedName() + ": " + aMsg);
367 private void warn(String aMsg) {
368 LOG.warn(getQualifiedName() + ": " + aMsg);
371 private String getServers(ProvidedInterface[] aProvidedList) {
373 for (ProvidedInterface provided : aProvidedList) {
374 result += "(components ";
375 for (Component component : _components) {
376 for (ProvidedInterface provided2 : component
377 .getProvidedInterfaces()) {
378 if (provided.equals(provided2)) {
379 result += component + " ";
383 result += ", interface " + provided + ")";
388 private List<Component> getClients(RequiredInterface aRequirement) {
389 List<Component> clients = new ArrayList<Component>();
390 for (Component component : _components) {
391 for (RequiredInterface required : component.getRequiredInterfaces()) {
392 if (required.equals(aRequirement)
393 && required.isOptional() == aRequirement.isOptional()) {
394 clients.add(component);
401 private void checkSealed() {
403 throw new SystemAssemblyException("Container is sealed");