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 validateProvidedInterfacesArePresent();
138 validateRequiredInterfaces();
140 doStartOptionalDryRun(null, true);
143 private void validateRequiredInterfaces() {
144 List<RequiredInterface> required = new ArrayList<RequiredInterface>();
145 for (Component component : _components) {
146 required.addAll(Arrays.asList(component.getRequiredInterfaces()));
149 for (RequiredInterface service : getRequiredInterfaces()) {
150 // TODO required interfaces by the component could be
151 // subclasses or implementations of the requirements
152 // of the contained components. The code below assumes
154 if (!(required.contains(service))) {
157 + "' indicated as required is not actually required by any of the components");
159 // Check for the case that the externally required service
160 // is optional whereas the internally required service is
162 if (service.isOptional()) {
163 for (RequiredInterface intf : required) {
164 if (intf.equals(service) && !intf.isOptional()) {
165 warn("Required service '"
167 + "' indicated as optional is mandatory by one of its components ("
171 + "), this can lead to problems when the container is started and the interface is not provided to the container.");
178 private void validateProvidedInterfacesArePresent() {
179 List<ProvidedInterface> provided = new ArrayList<ProvidedInterface>();
180 for (Component component : _components) {
181 provided.addAll(Arrays.asList(component.getProvidedInterfaces()));
183 for (ProvidedInterface service : getProvidedInterfaces()) {
184 // TODO provided interfaces by components could be
185 // provide subclasses or implementations of the
186 // provided interfaces of the container.
187 // The code below assumes an exact match.
188 if (!(provided.contains(service))) {
189 throw new SystemAssemblyException(getName() + ": Service '"
191 + "' is not provided by any of its components");
197 * Starts the container. After the container is started, the container
198 * becomes sealed meaning that no further components, required or provided
199 * interfaces may be added.
203 public Scope start() {
206 Scope scope = super.start(new DefaultScope(new ProvidedInterface[0]));
212 * Seal the container, meaning that no further components or interfaces may
220 * Checks if the container is sealed.
222 * @return True iff the container is sealed.
224 public boolean isSealed() {
229 protected Scope doStart(Scope aExternalScope) {
230 return doStartOptionalDryRun(aExternalScope, false);
233 private Scope doStartOptionalDryRun(Scope aExternalScope, boolean aDryRun) {
234 LOG.info("Starting '" + getQualifiedName() + "'");
236 Scope scope = new DefaultScope(getProvidedInterfaces(), aExternalScope);
238 List<ProvidedInterface> allProvided = new ArrayList<ProvidedInterface>();
240 addProvidersOfRequiredInterfaces(allProvided);
242 List<Component> started = new ArrayList<Component>();
243 for (Component component : _components) {
245 initializeProvidersForRequiredInterfaces(allProvided,
248 // Start the service.
250 Object runtime = component.start(scope);
251 scope.addRuntime(component, runtime);
252 started.add(component);
255 // add all provided services
256 ProvidedInterface[] provided = component
257 .getProvidedInterfaces();
258 allProvided.addAll(Arrays.asList(provided));
259 } catch (SystemAssemblyException e) {
261 } catch (RuntimeException e) {
262 LOG.error(getQualifiedName() + ": could not start '"
263 + component.getQualifiedName() + "'", e);
264 stopAlreadyStartedComponents(started, scope);
271 private void addProvidersOfRequiredInterfaces(
272 List<ProvidedInterface> allProvided) {
273 // all interfaces from the required list of this container are
274 // provided to the components inside it.
275 RequiredInterface[] required = getRequiredInterfaces();
276 for (RequiredInterface intf : required) {
277 ProvidedInterface provider = intf.getProvider();
278 if (provider != null) {
279 allProvided.add(provider);
281 if (!intf.isOptional()) {
282 throw new SystemAssemblyException(getQualifiedName()
283 + ": required interface '" + intf
284 + "' is not provided");
290 private void stopAlreadyStartedComponents(List<Component> aStarted,
292 // an exception occurred, stop the successfully started
294 for (int i = aStarted.size() - 1; i >= 0; i--) {
296 Component component = aStarted.get(i);
297 aStarted.get(i).stop(aScope.getRuntime(component));
298 } catch (Throwable t) {
299 LOG.error(getQualifiedName() + ": error stopping "
300 + aStarted.get(i).getQualifiedName());
306 * Sets the provided interface or a component.
308 * @param aAllProvided
309 * All available provided interfaces.
311 * Component whose required interfaces we are looking at.
312 * @param aValidateOnly
313 * If true then the provider will not be set for required
316 private void initializeProvidersForRequiredInterfaces(
317 List<ProvidedInterface> aAllProvided, Component aComponent,
318 boolean aValidateOnly) {
319 // Check if all required services are already provided by
323 for (RequiredInterface descriptor : aComponent.getRequiredInterfaces()) {
324 ProvidedInterface[] filtered = filterProvidedServices(descriptor,
326 if (filtered.length == 1) {
327 if (!aValidateOnly) {
328 descriptor.setProvider(filtered[0]);
330 } else if (filtered.length > 1) {
331 throw new SystemAssemblyException(
334 + "' required by system '"
336 + "' matches multiple services provided by other systems: "
337 + getServers(filtered));
339 // filtered.length == 0
340 if (!descriptor.isOptional()) {
341 throw new SystemAssemblyException(
344 + "' required by system '"
346 + "' is not provided by systems that are started earlier");
353 protected void doStop(Scope aScope) {
354 for (int i = _components.size() - 1; i >= 0; i--) {
355 Component component = _components.get(i);
356 Object runtime = aScope.getRuntime(component);
357 component.stop(runtime);
361 private void info(String aMsg) {
362 LOG.info(getQualifiedName() + ": " + aMsg);
365 private void warn(String aMsg) {
366 LOG.warn(getQualifiedName() + ": " + aMsg);
369 private String getServers(ProvidedInterface[] aProvidedList) {
371 for (ProvidedInterface provided : aProvidedList) {
372 result += "(components ";
373 for (Component component : _components) {
374 for (ProvidedInterface provided2 : component
375 .getProvidedInterfaces()) {
376 if (provided.equals(provided2)) {
377 result += component + " ";
381 result += ", interface " + provided + ")";
386 private List<Component> getClients(RequiredInterface aRequirement) {
387 List<Component> clients = new ArrayList<Component>();
388 for (Component component : _components) {
389 for (RequiredInterface required : component.getRequiredInterfaces()) {
390 if (required.equals(aRequirement)
391 && required.isOptional() == aRequirement.isOptional()) {
392 clients.add(component);
399 private void checkSealed() {
401 throw new SystemAssemblyException("Container is sealed");