Using GeoRss

I started using Marc’s GeoRss module as part of a webapp that needed to send geometries to an OpenLayers (JavaScript) client. Here are the steps I took to get GeoRss working.

* Read the documentation at http://georss.geonames.org/

* Used the following maven command to setup a basic project.

[sourcecode language=”bash”]
#!/bin/bash

PROJECT=twotrack

mvn archetype:generate \
-DarchetypeGroupId=org.apache.maven.archetypes \
-DarchetypeArtifactId=maven-archetype-profiles \
-Dversion=1.0.0-SNAPSHOT \
-DartifactId=$PROJECT-georss \
-DgroupId=net.fnarg.$PROJECT
[/sourcecode]

* Added GeoRss dependencies to the maven generated pom.xml

[sourcecode language=”xml”]
<dependency>
<groupId>rome</groupId>
<artifactId>rome</artifactId>
<version>0.9</version>
</dependency>
<dependency>
<groupId>org.geonames</groupId>
<artifactId>georss-rome</artifactId>
<version>0.9.8</version>
</dependency>
[/sourcecode]

* Grabbed the jars for Eclipse

[sourcecode language=”xml”]
mvn eclipse:eclipse
[/sourcecode]

* Extended Marc’s examples by wrapping some setters and getters for Spring

[sourcecode lanuage=”java”]
package net.fnarg.twotrack;

import java.net.URL;
import java.util.ArrayList;
import java.util.List;

import com.sun.syndication.io.XmlReader;
import com.sun.syndication.io.SyndFeedInput;
import com.sun.syndication.io.SyndFeedOutput;

import com.sun.syndication.feed.synd.SyndEntry;
import com.sun.syndication.feed.synd.SyndEntryImpl;
import com.sun.syndication.feed.synd.SyndFeed;
import com.sun.syndication.feed.synd.SyndFeedImpl;

import com.sun.syndication.feed.module.georss.GeoRSSUtils;
import com.sun.syndication.feed.module.georss.GeoRSSModule;
import com.sun.syndication.feed.module.georss.W3CGeoModuleImpl;
import com.sun.syndication.feed.module.georss.geometries.Position;

public class GeoRssFeed {
private SyndFeed feed;

public GeoRssFeed() {
feed = new SyndFeedImpl();
}

public GeoRssFeed(String url) throws Exception {
feed = new SyndFeedImpl();
this.setEntries(url);
}

public String getFeed() throws Exception {
return new SyndFeedOutput().outputString(feed);
}

public void setFeed() throws Exception {
feed.setFeedType("rss_2.0");
feed.setTitle("Two Track");
feed.setDescription("A tool for modelling toy train tracks");
feed.setLink("http://www.fnarg.net/twotrack/");
}

public void setEntries(String url) throws Exception {
SyndFeedInput input = new SyndFeedInput();
feed = input.build(new XmlReader(new URL(url)));
}

public List<SyndEntry> getEntries() {
return feed.getEntries();
}

public void setEntries(List<Position> positions) {
List<SyndEntry> entries = new ArrayList<SyndEntry>();
for (Position p : positions) {
SyndEntry entry = new SyndEntryImpl();
GeoRSSModule geoRSSModule = new W3CGeoModuleImpl();
geoRSSModule.setPosition(p);
entry.getModules().add(geoRSSModule);
entries.add(entry);
}
feed.setEntries(entries);
}
}
[/sourcecode]

* Wrote a test class to verify inputs/outputs

[sourcecode language=”java”]
package net.fnarg.twotrack;

import java.util.ArrayList;
import java.util.List;

import com.sun.syndication.feed.module.georss.GeoRSSModule;
import com.sun.syndication.feed.module.georss.GeoRSSUtils;
import com.sun.syndication.feed.module.georss.geometries.Position;
import com.sun.syndication.feed.synd.SyndEntry;

public class TestGeoRssReadWriter {

private static GeoRssFeed geoRssFeed;

/**
* Tester for the GeoRssFeed class
* @author gavin
*/
public static void main(String[] args) throws Exception {
// load XML file into memory
geoRssFeed = new GeoRssFeed("http://www.openlayers.org/dev/examples/xml/track1.xml");
// get and display the geometries
List<SyndEntry> entries = geoRssFeed.getEntries();
for (SyndEntry entry : entries) {
GeoRSSModule geoRSSModule = GeoRSSUtils.getGeoRSS(entry);
System.out.println(entry.getTitle() + " : lat="
+ geoRSSModule.getPosition().getLatitude() + ",lng="
+ geoRSSModule.getPosition().getLongitude() + ", desc="
+ entry.getDescription().getValue() + "; time="
+ entry.getPublishedDate());
}
// set mandatory XML fields with our Two Track headers
geoRssFeed.setFeed();
// output
System.out.println(geoRssFeed.getFeed());
// update the feed
Position p1 = new Position(54.2, 12.4);
Position p2 = new Position(55.2, 13.4);
List<Position> newEntries = new ArrayList<Position>();
newEntries.add(p1);
newEntries.add(p2);
// replace the geometries
geoRssFeed.setEntries(newEntries);
// check new output
System.out.println(geoRssFeed.getFeed());
}
}
[/sourcecode]