+/*
+ * Copyright 2007 the original author or authors.
+ *
+ * Licensed 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.wamblee.system;
import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
import java.util.HashMap;
+import java.util.HashSet;
import java.util.List;
import java.util.Map;
+import java.util.Set;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
- * Assembler to control multiple subsystems. It makes sure that
- * all dependencies are met and controls the order in which systems
- * are initialized.
+ * Assembler to control multiple subsystems. It makes sure that all dependencies
+ * are met and controls the order in which systems are initialized.
+ *
+ * @author Erik Brakkee
*/
public class SystemAssembler {
private static final String ROOT_CONTEXT_NAME = "root";
private String _context;
- private SubSystem[] _systems;
+ private Component[] _systems;
+ private ProvidedInterface[] _required;
+
+ public static RequiredInterface[] filterRequiredServices(
+ ProvidedInterface aProvided,
+ Collection<RequiredInterface> aDescriptors) {
+ List<RequiredInterface> required = new ArrayList<RequiredInterface>();
+ for (RequiredInterface descriptor : aDescriptors) {
+ if (descriptor.implementedBy(aProvided)) {
+ required.add(descriptor);
+ }
+ }
+ return required.toArray(new RequiredInterface[0]);
+ }
+
+ public static ProvidedInterface[] filterProvidedServices(
+ RequiredInterface aRequired,
+ Collection<ProvidedInterface> aProvided) {
+ List<ProvidedInterface> provided = new ArrayList<ProvidedInterface>();
+ for (ProvidedInterface descriptor : aProvided) {
+ if (aRequired.implementedBy(descriptor)) {
+ provided.add(descriptor);
+ }
+ }
+ return provided.toArray(new ProvidedInterface[0]);
+ }
/**
- * Constructs the assembler.
- * @param aSystems Systems that must be assembled.
- * @param aAvailableServices Available services from other systems
- * outside of the systems that this assembler manages.
+ * Constructs the assembler.
+ *
+ * @param aSystems
+ * Systems that must be assembled.
+ * @param aAvailableServices
+ * Available services from other systems outside of the systems
+ * that this assembler manages.
*/
- public SystemAssembler(SubSystem[] aSystems, ServiceDescriptor[] aAvailableServices) {
+ public SystemAssembler(Component[] aSystems,
+ ProvidedInterface[] aAvailableServices) {
this(ROOT_CONTEXT_NAME, aSystems, aAvailableServices);
}
/**
- * Constructs the assembler.
- * @param aContext Context (unique name) of the assembler.
- * @param aSystems Systems that must be assembled.
- * @param aAvailableServices Available services from other systems
- * outside of the systems that this assembler manages.
+ * Constructs the assembler.
+ *
+ * @param aContext
+ * Context (unique name) of the assembler.
+ * @param aSystems
+ * Systems that must be assembled.
+ * @param aAvailableServices
+ * Available services from other systems outside of the systems
+ * that this assembler manages.
*/
- public SystemAssembler(String aContext, SubSystem[] aSystems,
- ServiceDescriptor[] aAvailableServices) {
+ public SystemAssembler(String aContext, Component[] aSystems,
+ ProvidedInterface[] aAvailableServices) {
_context = aContext;
_systems = aSystems;
- validate(aAvailableServices);
+ _required = aAvailableServices;
+ validate();
}
/**
* Determines if the systems are ordered appropriately so that all
* dependencies are met.
*/
- private void validate(ServiceDescriptor[] aDescriptors) throws SystemAssemblyException {
+ private void validate()
+ throws SystemAssemblyException {
- List<ServiceDescriptor> allProvided = new ArrayList<ServiceDescriptor>();
- for (ServiceDescriptor descriptor: aDescriptors) {
+ List<ProvidedInterface> allProvided = new ArrayList<ProvidedInterface>();
+ for (ProvidedInterface descriptor : _required) {
allProvided.add(descriptor);
}
- for (SubSystem system : _systems) {
+ for (Component system : _systems) {
// Check if all required services are already provided by earlier
// systems.
- ServiceDescriptor[] required = system.getRequiredServices();
- for (ServiceDescriptor descriptor : required) {
- if (!(allProvided.contains(descriptor))) {
+ RequiredInterface[] required = system.getRequiredServices();
+
+ for (RequiredInterface descriptor : required) {
+ ProvidedInterface[] filtered = filterProvidedServices(
+ descriptor, allProvided);
+
+ if (filtered.length == 0) {
throw new SystemAssemblyException(
"Service '"
+ descriptor
+ system
+ "' is not provided by systems that are started earlier");
}
+ if (filtered.length > 1) {
+ throw new SystemAssemblyException(
+ "Service '"
+ + descriptor
+ + "' required by system '"
+ + system
+ + "' matches multiple services provided by other systems: " +
+ Arrays.asList(filtered));
+ }
}
// add all provided services
- ServiceDescriptor[] provided = system.getProvidedServices();
- for (ServiceDescriptor descriptor : provided) {
- allProvided.add(descriptor);
- }
+ ProvidedInterface[] provided = system.getProvidedServices();
+ allProvided.addAll(Arrays.asList(provided));
}
}
/**
* Starts the subsystems.
- * @param aRegistry Service registry to which created services must be registered.
- * @param aRequiredServices Services that are available from
- * other systems that have been started before.
+ *
+ * @param aRequiredServices
+ * Services that are available from other systems that have been
+ * started before.
*/
- public void start(ServiceRegistry aRegistry, Service[] aRequiredServices) {
+ public void start() {
LOG.info("Starting '" + _context + "'");
- Map<ServiceDescriptor, Service> allProvided = new HashMap<ServiceDescriptor, Service>();
-
- for (Service service : aRequiredServices) {
- allProvided.put(service.getDescriptor(), service);
- }
- for (SubSystem system : _systems) {
- ServiceDescriptor[] descriptors = system.getRequiredServices();
- List<Service> services = new ArrayList<Service>();
- for (ServiceDescriptor descriptor : descriptors) {
- Service required = allProvided.get(descriptor);
- if (required == null) {
- throw new SystemAssemblyException("Service '" + descriptor
- + "' required by '" + system + "' is null.");
- }
- services.add(required);
+ Set<ProvidedInterface> allProvided = new HashSet<ProvidedInterface>();
+ allProvided.addAll(Arrays.asList(_required));
+
+ for (Component system : _systems) {
+
+ // Compose a list of the required services required for the subsystem.
+
+ RequiredInterface[] descriptors = system
+ .getRequiredServices();
+ List<ProvidedInterface> services = new ArrayList<ProvidedInterface>();
+ for (RequiredInterface required : descriptors) {
+ ProvidedInterface[] provided = filterProvidedServices(
+ required, allProvided);
+ assert provided.length == 1;
+ services.add(provided[0]);
+ required.setProvider(provided[0]);
}
- Service[] provided = system.start(_context, aRegistry, services
- .toArray(new Service[0]));
- for (Service service : provided) {
- allProvided.put(service.getDescriptor(), service);
+
+ // Start the service.
+ system.start(_context);
+
+ // Add started services to the set of started services.
+ for (ProvidedInterface service : system.getProvidedServices()) {
+ allProvided.add(service);
}
}
git://wamblee.org / utils / blobdiff