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Carrot2 search results clustering framework. Minimal functional subset
(core algorithms and infrastructure, no document sources).
/*
* Carrot2 project.
*
* Copyright (C) 2002-2016, Dawid Weiss, Stanisław Osiński.
* All rights reserved.
*
* Refer to the full license file "carrot2.LICENSE"
* in the root folder of the repository checkout or at:
* http://www.carrot2.org/carrot2.LICENSE
*/
package org.carrot2.source.xml;
import java.io.InputStream;
import java.util.List;
import java.util.Map;
import javax.xml.transform.Templates;
import org.apache.http.HttpStatus;
import org.apache.http.client.HttpResponseException;
import org.carrot2.core.Document;
import org.carrot2.core.HttpAuthHub;
import org.carrot2.core.IControllerContext;
import org.carrot2.core.ProcessingException;
import org.carrot2.core.ProcessingResult;
import org.carrot2.core.attribute.AttributeNames;
import org.carrot2.core.attribute.Internal;
import org.carrot2.core.attribute.Processing;
import org.carrot2.source.SearchEngineResponse;
import org.carrot2.source.SimpleSearchEngine;
import org.carrot2.util.attribute.Attribute;
import org.carrot2.util.attribute.AttributeLevel;
import org.carrot2.util.attribute.Bindable;
import org.carrot2.util.attribute.Group;
import org.carrot2.util.attribute.Input;
import org.carrot2.util.attribute.Label;
import org.carrot2.util.attribute.Level;
import org.carrot2.util.httpclient.HttpRedirectStrategy;
import org.carrot2.util.httpclient.HttpUtils;
import org.carrot2.util.resource.IResource;
/**
* A base class for implementing data sources based on XML/XSLT. The XSLT stylesheet will
* be loaded once during component initialization and cached for all further requests.
*/
@Bindable
public abstract class RemoteXmlSimpleSearchEngineBase extends SimpleSearchEngine
{
/** A helper class that groups common functionality for XML/XSLT based data sources. */
public final XmlDocumentSourceHelper xmlDocumentSourceHelper = new XmlDocumentSourceHelper();
/**
* HTTP redirect response strategy (follow or throw an error).
*/
@Input
@Processing
@Attribute
@Label("HTTP redirect strategy")
@Level(AttributeLevel.MEDIUM)
@Group(SimpleSearchEngine.SERVICE)
@Internal
public HttpRedirectStrategy redirectStrategy = HttpRedirectStrategy.NO_REDIRECTS;
/** XSLT transformation to Carrot2 DTD */
private Templates toCarrot2Xslt;
@Override
public void init(IControllerContext context)
{
super.init(context);
toCarrot2Xslt = xmlDocumentSourceHelper.loadXslt(getXsltResource());
}
@Override
public void beforeProcessing() throws ProcessingException
{
super.beforeProcessing();
if (toCarrot2Xslt == null)
{
throw new ProcessingException("XSLT stylesheet must not be null");
}
}
@Override
protected SearchEngineResponse fetchSearchResponse() throws Exception
{
final String serviceURL = buildServiceUrl();
final SearchEngineResponse response = new SearchEngineResponse();
final ProcessingResult processingResult = loadProcessingResult(
serviceURL,
toCarrot2Xslt,
getXsltParameters(),
response.metadata,
getUser(),
getPassword(),
redirectStrategy);
final List documents = processingResult.getDocuments();
if (documents != null)
{
response.results.addAll(documents);
final Map resultAttributes = processingResult.getAttributes();
response.metadata
.put(SearchEngineResponse.RESULTS_TOTAL_KEY, resultAttributes
.containsKey(AttributeNames.RESULTS_TOTAL) ? resultAttributes
.get(AttributeNames.RESULTS_TOTAL) : (long) documents.size());
}
else
{
response.metadata.put(SearchEngineResponse.RESULTS_TOTAL_KEY, 0L);
}
afterFetch(response);
afterFetch(response, processingResult);
return response;
}
/**
* Invoked after the response has been partially parsed and {@link ProcessingResult}
* deserialized.
*/
protected void afterFetch(SearchEngineResponse response, ProcessingResult processingResult)
{
// Empty by default.
}
/**
* Returns the XSLT stylesheet that transforms the custom XML into Carrot2 compliant
* XML. This method will be called once during component initialization.
* Initialization time attributes will have been bound before the call to this method.
*/
protected abstract IResource getXsltResource();
/**
* Returns parameters to be passed to the XSLT transformer. This method will be called
* once per processing cycle. Processing-time attributes will have been bound before
* this method the call to this method. The default implementation returns
* null.
*/
protected Map getXsltParameters()
{
return null;
}
/**
* Builds the URL from which XML stream will be fetched. This method will be called
* once per request processing cycle. Processing-time attributes will have been bound
* before this method the call to this method.
*/
protected abstract String buildServiceUrl();
/**
* Returns the user name to use for HTTP Basic Authentication.
*/
protected String getUser()
{
return HttpAuthHub.getUser();
}
/**
* Returns the password to use for HTTP Basic Authentication.
*/
protected String getPassword()
{
char[] password = HttpAuthHub.getPassword();
return password == null ? null : new String(password);
}
/**
* Loads a {@link ProcessingResult} from the provided remote URL, applying XSLT
* transform if specified. This method can handle gzip-compressed streams if supported
* by the data source.
*
* @param metadata if a non-null map is provided, request metadata will
* be put into the map.
* @param user if not null, the user name to use for HTTP Basic
* Authentication
* @param password if not null, the password to use for HTTP Basic
* Authentication
*/
protected ProcessingResult loadProcessingResult(String url, Templates stylesheet,
Map xsltParameters, Map metadata, String user,
String password, HttpRedirectStrategy redirectStrategy) throws Exception
{
final HttpUtils.Response response = HttpUtils.doGET(
url,
null, null,
user, password,
xmlDocumentSourceHelper.timeout * 1000,
redirectStrategy.value());
final InputStream carrot2XmlStream = response.getPayloadAsStream();
final int statusCode = response.status;
if (statusCode == HttpStatus.SC_OK)
{
metadata.put(SearchEngineResponse.COMPRESSION_KEY, response.compression);
return xmlDocumentSourceHelper.loadProcessingResult(carrot2XmlStream, stylesheet, xsltParameters);
}
else
{
throw new HttpResponseException(statusCode, response.statusMessage);
}
}
}