// Copyright 2007 The Apache Software Foundation
//
// 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.apache.hivemind.impl;
import java.util.Iterator;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hivemind.ErrorHandler;
import org.apache.hivemind.Location;
import org.apache.hivemind.definition.ConfigurationParserDefinition;
import org.apache.hivemind.definition.ConfigurationPointDefinition;
import org.apache.hivemind.definition.ContributionDefinition;
import org.apache.hivemind.definition.DefinitionMessages;
import org.apache.hivemind.definition.ModuleDefinition;
import org.apache.hivemind.definition.RegistryDefinition;
import org.apache.hivemind.definition.ImplementationDefinition;
import org.apache.hivemind.definition.InterceptorDefinition;
import org.apache.hivemind.definition.ServicePointDefinition;
import org.apache.hivemind.definition.UnresolvedExtension;
import org.apache.hivemind.definition.Visibility;
import org.apache.hivemind.util.IdUtils;
/**
* Resolves the {@link UnresolvedExtension unresolved extensions} in all
* modules of a {@link RegistryDefinition} during
* the construction of a registry by {@link RegistryBuilder}.
* Every unresolved extension (e.g. contribution, interceptor) references
* an extension point by its fully qualified id. This class looks for these
* extension points in the registry definition and adds the formerly unresolved
* extension directly to the extension points.
* The error handling is delegated to an instance of {@link ErrorHandler}.
*
* @author Achim Huegen
*/
public class ExtensionResolver
{
private static final Log LOG = LogFactory.getLog(ExtensionResolver.class);
private ErrorHandler _errorHandler;
private RegistryDefinition _definition;
public ExtensionResolver(RegistryDefinition definition, ErrorHandler errorHandler)
{
_errorHandler = errorHandler;
_definition = definition;
}
/**
* Resolves all unresolved extensions in the registry definition passed in the constructor.
* During this process the object graph represented by the registry definition is changed,
* so that afterwards it doesn't contain unresolved extensions any longer if anything went ok.
* If errors occur it depends on the assigned {@link ErrorHandler} whether an exceptions
* is raised or errors are logged only. In the latter case all extensions that couldn't
* be resolved will remain in the module definitions.
*/
public void resolveExtensions()
{
for (Iterator iterModules = _definition.getModules().iterator(); iterModules.hasNext();)
{
ModuleDefinition module = (ModuleDefinition) iterModules.next();
resolveImplementations(module);
resolveInterceptors(module);
resolveContributions(module);
resolveConfigurationParsers(module);
}
}
private void resolveImplementations(ModuleDefinition module)
{
for (Iterator iter = module.getImplementations().iterator(); iter.hasNext();)
{
UnresolvedExtension unresolved = (UnresolvedExtension) iter.next();
String servicePointId = unresolved.getExtensionPointId();
if (LOG.isDebugEnabled()) {
LOG.debug("Trying to resolve service point " + servicePointId + " referenced by" +
" implementation" + logLocation(unresolved.getExtension().getLocation()));
}
ServicePointDefinition servicePoint = _definition.getServicePoint(servicePointId);
if (servicePoint == null)
{
_errorHandler.error(
LOG,
DefinitionMessages.unknownServicePoint(
IdUtils.extractModule(servicePointId),
IdUtils.stripModule(servicePointId)),
unresolved.getExtension().getLocation(),
null);
} else {
servicePoint.addImplementation((ImplementationDefinition) unresolved.getExtension());
}
iter.remove();
}
}
private String logLocation(Location location)
{
if (location == null) {
return "";
} else {
return " at " + location.toString();
}
}
private void resolveInterceptors(ModuleDefinition module)
{
for (Iterator iter = module.getInterceptors().iterator(); iter.hasNext();)
{
UnresolvedExtension unresolved = (UnresolvedExtension) iter.next();
String servicePointId = unresolved.getExtensionPointId();
if (LOG.isDebugEnabled()) {
LOG.debug("Trying to resolve service point " + servicePointId + " referenced by" +
" interceptor" + logLocation(unresolved.getExtension().getLocation()));
}
ServicePointDefinition servicePoint = _definition.getServicePoint(servicePointId);
if (servicePoint == null)
{
_errorHandler.error(
LOG,
DefinitionMessages.unknownServicePoint(
IdUtils.extractModule(servicePointId),
IdUtils.stripModule(servicePointId)),
unresolved.getExtension().getLocation(),
null);
} else {
servicePoint.addInterceptor((InterceptorDefinition) unresolved.getExtension());
}
iter.remove();
}
}
private void resolveContributions(ModuleDefinition module)
{
for (Iterator iter = module.getContributions().iterator(); iter.hasNext();)
{
UnresolvedExtension unresolved = (UnresolvedExtension) iter.next();
String configurationPointId = unresolved.getExtensionPointId();
if (LOG.isDebugEnabled()) {
LOG.debug("Trying to resolve configuration point " + configurationPointId + " referenced by" +
" contribution " + logLocation(unresolved.getExtension().getLocation()));
}
ConfigurationPointDefinition configurationPoint = _definition.getConfigurationPoint(configurationPointId);
if (configurationPoint == null)
{
_errorHandler.error(
LOG,
DefinitionMessages.unknownConfigurationPoint(
IdUtils.extractModule(configurationPointId),
IdUtils.stripModule(configurationPointId)),
unresolved.getExtension().getLocation(),
null);
} else {
configurationPoint.addContribution((ContributionDefinition) unresolved.getExtension());
}
iter.remove();
}
}
private void resolveConfigurationParsers(ModuleDefinition module)
{
for (Iterator iter = module.getConfigurationParsers().iterator(); iter.hasNext();)
{
UnresolvedExtension unresolved = (UnresolvedExtension) iter.next();
String configurationPointId = unresolved.getExtensionPointId();
if (LOG.isDebugEnabled()) {
LOG.debug("Trying to resolve configuration point " + configurationPointId + " referenced by" +
" ConfigurationParser " + logLocation(unresolved.getExtension().getLocation()));
}
ConfigurationPointDefinition configurationPoint = _definition.getConfigurationPoint(configurationPointId);
if (configurationPoint == null)
{
_errorHandler.error(
LOG,
DefinitionMessages.unknownConfigurationPoint(
IdUtils.extractModule(configurationPointId),
IdUtils.stripModule(configurationPointId)),
unresolved.getExtension().getLocation(),
null);
} else {
if (Visibility.PRIVATE.equals(configurationPoint.getVisibility())
&& !module.getId().equals(IdUtils.extractModule(configurationPointId))) {
_errorHandler.error(
LOG,
DefinitionMessages.configurationPointNotVisible(
configurationPoint,
module),
unresolved.getExtension().getLocation(),
null);
}
configurationPoint.addParser((ConfigurationParserDefinition) unresolved.getExtension());
}
iter.remove();
}
}
}