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 addProvidersOfRequiredInterfaces(provided);
151 validateRequiredProvidedMatch(provided, required);
157 * All provided interfaces.
159 * All required interfaces.
162 private void validateRequiredProvidedMatch(
163 List<ProvidedInterface> aProvided, List<RequiredInterface> aRequired) {
165 for (Component component : _components) {
166 initializeProvidersForRequiredInterfaces(aProvided, component, true);
170 private void validateRequiredInterfaces(List<RequiredInterface> aRequired) {
171 for (RequiredInterface service : getRequiredInterfaces()) {
172 // TODO required interfaces by the component could be
173 // subclasses or implementations of the requirements
174 // of the contained components. The code below assumes
176 if (!(aRequired.contains(service))) {
179 + "' indicated as required is not actually required by any of the components");
181 // Check for the case that the externally required service
182 // is optional whereas the internally required service is
184 if (service.isOptional()) {
185 for (RequiredInterface intf : aRequired) {
186 if (intf.equals(service) && !intf.isOptional()) {
187 warn("Required service '"
189 + "' indicated as optional is mandatory by one of its components ("
193 + "), this can lead to problems when the container is started and the interface is not provided to the container.");
200 private void validateProvidedInterfacesArePresent(
201 List<ProvidedInterface> aProvided) {
202 for (ProvidedInterface service : getProvidedInterfaces()) {
203 // TODO provided interfaces by components could be
204 // provide subclasses or implementations of the
205 // provided interfaces of the container.
206 // The code below assumes an exact match.
207 if (!(aProvided.contains(service))) {
208 throw new SystemAssemblyException(getName() + ": Service '"
210 + "' is not provided by any of its components");
216 * Starts the container. After the container is started, the container
217 * becomes sealed meaning that no further components, required or provided
218 * interfaces may be added.
222 public Scope start() {
225 Scope scope = super.start(new DefaultScope(new ProvidedInterface[0]));
231 * Seal the container, meaning that no further components or interfaces may
239 * Checks if the container is sealed.
241 * @return True iff the container is sealed.
243 public boolean isSealed() {
248 protected Scope doStart(Scope aExternalScope) {
249 LOG.info("Starting '" + getQualifiedName() + "'");
251 Scope scope = new DefaultScope(getProvidedInterfaces(), aExternalScope);
253 List<ProvidedInterface> allProvided = new ArrayList<ProvidedInterface>();
255 addProvidersOfRequiredInterfaces(allProvided);
257 List<Component> started = new ArrayList<Component>();
258 for (Component component : _components) {
260 initializeProvidersForRequiredInterfaces(allProvided,
263 // Start the service.
264 Object runtime = component.start(scope);
265 scope.addRuntime(component, runtime);
266 started.add(component);
268 // add all provided services
269 ProvidedInterface[] provided = component
270 .getProvidedInterfaces();
271 allProvided.addAll(Arrays.asList(provided));
272 } catch (SystemAssemblyException e) {
274 } catch (RuntimeException e) {
275 LOG.error(getQualifiedName() + ": could not start '"
276 + component.getQualifiedName() + "'", e);
277 stopAlreadyStartedComponents(started, scope);
284 private void addProvidersOfRequiredInterfaces(
285 List<ProvidedInterface> allProvided) {
286 // all interfaces from the required list of this container are
287 // provided to the components inside it.
288 RequiredInterface[] required = getRequiredInterfaces();
289 for (RequiredInterface intf : required) {
290 ProvidedInterface provider = intf.getProvider();
291 if (provider != null) {
292 allProvided.add(provider);
294 if (!intf.isOptional()) {
295 throw new SystemAssemblyException(getQualifiedName()
296 + ": required interface '" + intf
297 + "' is not provided");
303 private void stopAlreadyStartedComponents(List<Component> aStarted,
305 // an exception occurred, stop the successfully started
307 for (int i = aStarted.size() - 1; i >= 0; i--) {
309 aStarted.get(i).stop(aScope);
310 } catch (Throwable t) {
311 LOG.error(getQualifiedName() + ": error stopping "
312 + aStarted.get(i).getQualifiedName());
318 * Sets the provided interface or a component.
320 * @param aAllProvided
321 * All available provided interfaces.
323 * Component whose required interfaces we are looking at.
324 * @param aValidateOnly
325 * If true then the provider will not be set for required
328 private void initializeProvidersForRequiredInterfaces(
329 List<ProvidedInterface> aAllProvided, Component aComponent,
330 boolean aValidateOnly) {
331 // Check if all required services are already provided by
335 for (RequiredInterface descriptor : aComponent.getRequiredInterfaces()) {
336 ProvidedInterface[] filtered = filterProvidedServices(descriptor,
338 if (filtered.length == 1) {
339 if (!aValidateOnly) {
340 descriptor.setProvider(filtered[0]);
342 } else if (filtered.length > 1) {
343 throw new SystemAssemblyException(
346 + "' required by system '"
348 + "' matches multiple services provided by other systems: "
349 + getServers(filtered));
351 // filtered.length == 0
352 if (!descriptor.isOptional()) {
353 throw new SystemAssemblyException(
356 + "' required by system '"
358 + "' is not provided by systems that are started earlier");
365 protected void doStop(Scope aScope) {
366 for (int i = _components.size() - 1; i >= 0; i--) {
367 Component component = _components.get(i);
368 Object runtime = aScope.getRuntime(component);
369 component.stop(runtime);
373 private void info(String aMsg) {
374 LOG.info(getQualifiedName() + ": " + aMsg);
377 private void warn(String aMsg) {
378 LOG.warn(getQualifiedName() + ": " + aMsg);
381 private String getServers(ProvidedInterface[] aProvidedList) {
383 for (ProvidedInterface provided : aProvidedList) {
384 result += "(components ";
385 for (Component component : _components) {
386 for (ProvidedInterface provided2 : component
387 .getProvidedInterfaces()) {
388 if (provided.equals(provided2)) {
389 result += component + " ";
393 result += ", interface " + provided + ")";
398 private List<Component> getClients(RequiredInterface aRequirement) {
399 List<Component> clients = new ArrayList<Component>();
400 for (Component component : _components) {
401 for (RequiredInterface required : component.getRequiredInterfaces()) {
402 if (required.equals(aRequirement)
403 && required.isOptional() == aRequirement.isOptional()) {
404 clients.add(component);
411 private void checkSealed() {
413 throw new SystemAssemblyException("Container is sealed");