/*
* Copyright 2012 Netflix, Inc.
*
* 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 com.netflix.recipes.rss.manager;
import java.io.IOException;
import java.io.StringReader;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.ArrayList;
import java.util.List;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.apache.commons.io.Charsets;
import org.apache.commons.io.IOUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import com.netflix.client.ClientFactory;
import com.netflix.config.DynamicPropertyFactory;
import com.netflix.karyon.spi.HealthCheckHandler;
import com.netflix.niws.client.http.HttpClientRequest;
import com.netflix.niws.client.http.HttpClientResponse;
import com.netflix.niws.client.http.RestClient;
import com.netflix.recipes.rss.RSS;
import com.netflix.recipes.rss.RSSConstants;
import com.netflix.recipes.rss.RSSItem;
import com.netflix.recipes.rss.RSSStore;
import com.netflix.recipes.rss.Subscriptions;
import com.netflix.recipes.rss.impl.CassandraStoreImpl;
import com.netflix.recipes.rss.impl.InMemoryStoreImpl;
import com.netflix.recipes.rss.impl.RSSImpl;
import com.netflix.recipes.rss.impl.RSSItemImpl;
import com.netflix.recipes.rss.impl.SubscriptionsImpl;
/**
* RSS Manager that
* 1) Fetches content from RSS feeds using Ribbon
* 2) Parses RSS feeds
* 3) Persists feed urls into
* a) Cassandra using Astyanax (or)
* b) InMemoryStore
*/
public class RSSManager implements HealthCheckHandler {
private RSSStore store;
private static final Logger logger = LoggerFactory.getLogger(RSSManager.class);
private static final RSSManager instance = new RSSManager();
private RSSManager() {
if (RSSConstants.RSS_STORE_CASSANDRA.equals(
DynamicPropertyFactory.getInstance().getStringProperty(RSSConstants.RSS_STORE, RSSConstants.RSS_STORE_CASSANDRA).get())) {
store = new CassandraStoreImpl();
} else {
store = new InMemoryStoreImpl();
}
}
public static RSSManager getInstance() {
return instance;
}
/**
* Fetches the User subscriptions
*/
public Subscriptions getSubscriptions(String userId) throws Exception {
List<String> feedUrls = store.getSubscribedUrls(userId);
List<RSS> feeds = new ArrayList<RSS>(feedUrls.size());
for (String feedUrl: feedUrls) {
RSS rss = RSSManager.getInstance().fetchRSSFeed(feedUrl);
if (rss.getItems() != null && !rss.getItems().isEmpty()) {
feeds.add(rss);
}
}
return new SubscriptionsImpl(userId, feeds);
}
/**
* Add subscription
*/
public void addSubscription(String user, String decodedUrl) throws Exception {
if (decodedUrl == null) throw new IllegalArgumentException("url cannot be null");
store.subscribeUrl(user, decodedUrl);
}
/**
* Delete subscription
*/
public void deleteSubscription(String user, String decodedUrl) throws Exception {
if (decodedUrl == null) throw new IllegalArgumentException("url cannot be null");
store.unsubscribeUrl(user, decodedUrl);
}
/**
* Fetch the RSS feed content using Ribbon
*/
private RSS fetchRSSFeed(String url) {
RestClient client = (RestClient) ClientFactory.getNamedClient(RSSConstants.MIDDLETIER_REST_CLIENT);
HttpClientResponse response;
String rssData = null;
try {
HttpClientRequest request = HttpClientRequest.newBuilder().setUri(new URI(url)).build();
response = client.execute(request);
if (response != null) {
rssData = IOUtils.toString(response.getRawEntity(), Charsets.UTF_8);
logger.info("Status code for " + response.getRequestedURI() + " : " + response.getStatus());
}
} catch (URISyntaxException e) {
logger.error("Exception occurred when setting the URI", e);
} catch (Exception e) {
logger.error("Exception occurred when executing the HTTP request", e);
}
return parseRSS(url, rssData);
}
/**
* Parses the RSS feeds and return back a POJO
*/
private RSS parseRSS(String url, String rss) {
// Error case
if (rss == null) return new RSSImpl();
RSS rssItems = null;
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
String FEATURE = "http://apache.org/xml/features/disallow-doctype-decl";
try {
dbf.setFeature(FEATURE, true);
DocumentBuilder db = dbf.newDocumentBuilder();
try {
InputSource is = new InputSource(new StringReader(rss));
Document dom = db.parse(is);
Element docEle = dom.getDocumentElement();
List<RSSItem> items = new ArrayList<RSSItem>();
String title = docEle.getElementsByTagName("title").item(0).getTextContent();
NodeList nl = docEle.getElementsByTagName("item");
if (nl != null && nl.getLength() > 0) {
for (int i = 0 ; i < nl.getLength(); i++) {
Element el = (Element) nl.item(i);
items.add(new RSSItemImpl(el.getElementsByTagName("title").item(0).getTextContent(), el.getElementsByTagName("link").item(0).getTextContent(), el.getElementsByTagName("description").item(0).getTextContent()));
}
}
rssItems = new RSSImpl(url, title, items);
} catch (SAXException e) {
logger.error("Exception occurred during parsing the RSS feed", e);
} catch (IOException e) {
logger.error("Exception occurred during fetching the RSS feed", e);
}
} catch (ParserConfigurationException e) {
logger.error("Exception occurred during parsing the RSS feed", e);
}
if (rssItems == null) {
rssItems = new RSSImpl();
}
return rssItems;
}
public int getStatus() {
return store == null ? 500 : 200;
}
}
