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Screencast #Web11: Travel Map - Another Real-life app using jMaki & Jersey

In my role of Technology Evangelist, I get the opportunity to meet a lot of community (folks like you :) all around the world. In the year 2007, I represented GlassFish (and related technologies - Metro, jMaki and Jersey) at multiple conferences. This blog introduces a  new real-life application that plots all the places I visited this year on a jMaki-wrapped Google Map widget. Clicking on the marker shows more information about the event such as dates and the blog entry covering the event.

Play the video below to see how the application looks like.

Here is the architecture of this application:

It consists of a server-side and a client-side applications - developed as NetBeans projects.

1. Server-side project - A RESTful Web service endpoint that provides resource represenations for all the events attended and associated meta information such as date and blog URLs. This endpoint is created using Jersey.
2. Client-side project - A jMaki-enabled Web application that consumes the representations generated by the RESTful Web service and plots the information on a jMaki-wrapped Google Map widget.

Both the server-side and client-side are deployed on GlassFish.

This is only a sample application so optimizations are certainly possible and corner cases (such as no blog entry for a particular visit) are not accounted for. But the application still demonstrates the concept. The fully built application looks like as shown below:

My first presentation in this role was Sun Tech Days Atlanta (highlighted in the image). This application generates an interactive Google Map so feel free to zoom in/out and click 

And one last thing before we build the application. Here is the list of technologies and associated concepts used to build this application:

1. Jersey
1. Shows an example of how RESTful Web services can be easily generated from JPA Entity Classes.
2. Shows how all the resource representations (instead of reference to individual resources) can be returned by a Jersey endpoint.
2. jMaki
1. Shows how to consume XML data from an external service (RESTful Web service endpoint) in this case.
2. Shows how the underlying data model of a widget (Google Map in this case) can be accessed and manipulated.
3. GlassFish
1. All the applications are deployed on GlassFish - implicit in the development/deplyment process through seamless integration with NetBeans.
4. NetBeans 6
1. Used for generation of RESTful Web services from JPA Entity Classes.
2. Used for generating/deploying jMaki projects and drag-and-drop of jMaki-wrapped widgets.
5. JavaScript Closures - to persist the state for asynchronous callback functions
6. JavaScript DOM processing - to process the XML data received from Jersey endpoint.
7. Google Maps API
1. Generate meaningful markers on each location
2. Populate Google Map from a RESTful Web service endpoint
8. Java Persistence API - to retrieve data from the database.

And finally, lets build this application. Lets build the RESTful Web service endpoint project first.

1. Create and Populate the Database
1. In the NetBeans IDE, go to Services tab, and connect to the database with URL "jdbc:derby://localhost:1527/sample [app on APP]" (right-click and select "Connect...").
2. Right-click on this database and select "Execute Command..." and create a table by giving the following command:
   
   create table EVENTS (id int GENERATED ALWAYS AS IDENTITY,
                    event_name varchar(255),
                    dates varchar(20),
                    venue varchar(255),
                    blogs varchar(2056),
                    PRIMARY KEY (id))
   
   Notice, the "id" column is marked as IDENTITY that instructs the database to auto generate the values for this column and increment by 1 (default) for each row. This column is also marked as the primary key.
3. Again right-click on the database and select "Execute Command..." to add data to the table by giving the following command:

INSERT INTO EVENTS (event_name, dates, venue, blogs) VALUES('SunTech Days - Atlanta', 'Jan 16 - Jan 17', 'Cobb Galleria Center, Two Galleria Parkway, Atlanta, Georgia, 30339', 'http://blogs.sun.com/arungupta/entry/wsit_and_web_2_0');
INSERT INTO EVENTS (event_name, dates, venue, blogs) VALUES('jMaki Day', ' Feb 23', '4150 Network Circle Santa Clara, CA 95054', 'http://blogs.sun.com/arungupta/entry/sun_internal_jmaki_day_review');
INSERT INTO EVENTS (event_name, dates, venue, blogs) VALUES('Ajax World - New York', 'Mar 19 - Mar 21', 'The Roosevelt Hotel, 45 E 45th St, New York, NY 10017', 'http://blogs.sun.com/arungupta/entry/sun_ajax_world');
INSERT INTO EVENTS (event_name, dates, venue, blogs) VALUES('The Server Side Java Symposium - Las Vegas', 'Mar 22', '3355 Las Vegas Blvd. South Las Vegas, NV 89109', 'http://blogs.sun.com/arungupta/entry/sun_the_server_side_java, http://blogs.sun.com/arungupta/entry/tango_at_venetian_las_vegas');
INSERT INTO EVENTS (event_name, dates, venue, blogs) VALUES('JavaOne - San Francisco', 'May 7 - May 11', 'Moscone Center, 747 Howard Street, San Francisco, CA 94103', 'http://blogs.sun.com/arungupta/entry/slides_for_ts_4865, http://blogs.sun.com/arungupta/entry/javaone_2007_day_1_finished, http://blogs.sun.com/arungupta/entry/javaone_2007_day_1, http://blogs.sun.com/arungupta/entry/javascript_everywhere_javaone_2007_demo, http://blogs.sun.com/arungupta/entry/excel_using_wsit_javaone_2007, http://blogs.sun.com/arungupta/entry/ts_4865_takes_two_to, http://blogs.sun.com/arungupta/entry/communityone_glassfish_day_report, http://blogs.sun.com/arungupta/entry/javaone_2007_backstage, http://blogs.sun.com/arungupta/entry/javaone_2007_is_almost_here, http://blogs.sun.com/arungupta/entry/my_javaone_2007_picks');
INSERT INTO EVENTS (event_name, dates, venue, blogs) VALUES('Rails Conf - Portland', 'May 17 - May 20', '777 NE MLK, Jr. Blvd. Portland, OR 97232', 'http://blogs.sun.com/arungupta/entry/tim_bray_s_keynote_session, http://blogs.sun.com/arungupta/entry/sun_rails_conf_2007_keep, http://blogs.sun.com/arungupta/entry/getting_started_with_jruby_tutorial, http://blogs.sun.com/arungupta/entry/jmaki_netbeans_and_glassfish_in');
INSERT INTO EVENTS (event_name, dates, venue, blogs) VALUES('Google Developer Day - San Jose', 'May 31', '150 W San Carlos St San Jose, CA 95113', 'http://blogs.sun.com/arungupta/entry/google_developer_day_report');
INSERT INTO EVENTS (event_name, dates, venue, blogs) VALUES('Mashup Camp - Mountain View', 'Jul 18 - Jul 19', 'Computer History Museum, 1401 N Shoreline Blvd., Mountain View, CA 94043', 'http://blogs.sun.com/arungupta/entry/jmaki_at_mashup_camp_report, http://blogs.sun.com/arungupta/entry/jmaki_mashup_camp');
INSERT INTO EVENTS (event_name, dates, venue, blogs) VALUES('OSCON - Portland', 'Jul 23 - Jul 27', '777 NE MLK, Jr. Blvd. Portland, OR 97232', 'http://blogs.sun.com/arungupta/entry/jmaki_oscon');
INSERT INTO EVENTS (event_name, dates, venue, blogs) VALUES('JRuby Hack Day - San Francisco', 'Aug 8', '1201 8th St, San Francisco, CA 94107', 'http://blogs.sun.com/arungupta/entry/jruby_on_rails_hackday_report, http://blogs.sun.com/arungupta/entry/learn_jruby_on_rails_free');
INSERT INTO EVENTS (event_name, dates, venue, blogs) VALUES('Rich Web Experience - San Jose', 'Sep 6 - Sep 8', '170 S Market St, San Jose, CA 95113', 'http://blogs.sun.com/arungupta/entry/the_rich_web_experience_2007, http://blogs.sun.com/arungupta/entry/jmaki_javafx_the_rich_web');
INSERT INTO EVENTS (event_name, dates, venue, blogs) VALUES('Rails Conf Europe - Berlin', 'Sep 17 - Sep 19', 'Maritim Pro Arte, Friedrichstrasse 151, 10117 Berlin', 'http://blogs.sun.com/arungupta/entry/rails_conf_europe_2007_day2, http://blogs.sun.com/arungupta/entry/rails_conf_europe_2007_day1, http://blogs.sun.com/arungupta/entry/rails_conf_europe_2007_day, http://blogs.sun.com/arungupta/entry/jmaki_netbeans_and_glassfish_in1');
INSERT INTO EVENTS (event_name, dates, venue, blogs) VALUES('Sun Tech Days - Rome', 'Sep 24 - Sep 25', 'Meliá Roma Aurelia Antica, Vía Aldobrandeschi, 223  Rome ITALY  00163', 'http://blogs.sun.com/arungupta/entry/netbeans_day_rome_2007, http://blogs.sun.com/arungupta/entry/travel_tips_to_rome, http://blogs.sun.com/arungupta/entry/glassfish_metro_jersey_and_jmaki');
INSERT INTO EVENTS (event_name, dates, venue, blogs) VALUES('Sun Tech Days - Milan', 'Sep 26 - Sep 28', 'ATA Hotel Quark - Via Lampedusa 11/a 20141 Milano, Italia', 'http://blogs.sun.com/arungupta/entry/glassfish_day_milan_2007');
INSERT INTO EVENTS (event_name, dates, venue, blogs) VALUES('Mid West Java Tech Days - Minneapolis', 'Oct 16', 'University of St Thomas, MPL 201, 1000 LaSalle Avenue, Minneapolis, MN 55403-2005', 'http://blogs.sun.com/arungupta/entry/mid_west_java_tech_days, http://blogs.sun.com/arungupta/entry/metro_and_jmaki_in_minneapolis');
INSERT INTO EVENTS (event_name, dates, venue, blogs) VALUES('Mid West Java Tech Days - Chicago', 'Oct 18', 'Donald E Stephens Convention Center, 9301, W Bryn Mawr Ave, Rosemont IL 60018', 'http://blogs.sun.com/arungupta/entry/mid_west_java_tech_days1, http://blogs.sun.com/arungupta/entry/crowne_plaza_chicago_o_hare, http://blogs.sun.com/arungupta/entry/metro_and_jmaki_in_minneapolis');
INSERT INTO EVENTS (event_name, dates, venue, blogs) VALUES('Silicon Valley Code Camp - Los Altos', 'Oct 27', 'Foothill College, Los Altos, CA', 'http://blogs.sun.com/arungupta/entry/silicon_valley_code_camp_trip, http://blogs.sun.com/arungupta/entry/metro_jmaki_silicon_valley_code');
INSERT INTO EVENTS (event_name, dates, venue, blogs) VALUES('Sun Tech Days - Beijing', 'Nov 1 - Nov 3', 'Beijing International Convention Center, No.8 Beichendong Road Chaoyang District, Beijing', 'http://blogs.sun.com/arungupta/entry/glassfish_day_beijing_2007_by, http://blogs.sun.com/arungupta/entry/wangfujing_street_authentic_china_in, http://blogs.sun.com/arungupta/entry/sun_tech_days_beijing_talent, http://blogs.sun.com/arungupta/entry/sun_tech_days_beijing_day, http://blogs.sun.com/arungupta/entry/travel_tips_to_beijing, http://blogs.sun.com/arungupta/entry/glassfish_day_beijing');
INSERT INTO EVENTS (event_name, dates, venue, blogs) VALUES('Partner Preso - Toronto', 'Nov 21', 'Toronto City Center', 'http://blogs.sun.com/arungupta/entry/metro_jmaki_jruby_glassfish_q');
INSERT INTO EVENTS (event_name, dates, venue, blogs) VALUES('Partner Preso - Montreal', 'Nov 21', 'Montreal City Center', 'http://blogs.sun.com/arungupta/entry/metro_jmaki_jruby_glassfish_q');
INSERT INTO EVENTS (event_name, dates, venue, blogs) VALUES('GlassFish - Delhi University', 'Dec 3', 'New Delhi', 'http://blogs.sun.com/arungupta/entry/glassfish_delhi_university');
INSERT INTO EVENTS (event_name, dates, venue, blogs) VALUES('FOSS.IN - Bangalore', 'Dec 4', 'India Institute of Science, Bangalore', 'http://blogs.sun.com/arungupta/entry/packaging_java_apps_for_ubuntu, http://blogs.sun.com/arungupta/entry/foss_in_schedules_now_available, http://blogs.sun.com/arungupta/entry/glassfish_foss_in_2007');
INSERT INTO EVENTS (event_name, dates, venue, blogs) VALUES('Partner Preso - Bangalore', 'Dec 4', 'Bangalore', 'http://blogs.sun.com/arungupta/entry/glassfish_bangalore_chennai_and_pune');
INSERT INTO EVENTS (event_name, dates, venue, blogs) VALUES('Partner Preso - Chennai', 'Dec 5', 'Chennai', 'http://blogs.sun.com/arungupta/entry/glassfish_bangalore_chennai_and_pune');
INSERT INTO EVENTS (event_name, dates, venue, blogs) VALUES('Partner Preso - Pune', 'Dec 6', 'Pune', 'http://blogs.sun.com/arungupta/entry/glassfish_bangalore_chennai_and_pune');
INSERT INTO EVENTS (event_name, dates, venue, blogs) VALUES('Partner Preso - San Francisco', 'Dec 17', 'San Francisco', 'http://blogs.sun.com/arungupta/');
   
   These SQL statements populate the database with details about my visits in 2007. If you'd like to develop a similar application highlighting your visits then you'll need to modify the VALUES clause to match accordingly.
   
2. Create and Configure RESTful Web service endpoint
1. Create a Persistence Unit as described in "Generating Entity Classes from Database" section in Getting Started with RESTful Web Services. Lets say the project name is "WebApplication3", package name is "events" and the table name to generate Entity classes is EVENTS. Take everything else as the defaults.
2. Generate a RESTful Web service as described in "Generating RESTful Web Services from Entity Classes" section in Getting Started with RESTful Web Services.
1. Add a new class EventsList in the events package as:
   
@javax.xml.bind.annotation.XmlRootElement
public class EventsList {
  @javax.xml.bind.annotation.XmlElement
  protected java.util.List<Events> events;

  public EventsList() {
    if (events == null)
      events = new java.util.ArrayList<Events>();
  }

  public void add(Events name) {
    events.add(name);
  }

  public java.util.List<Events> getValue() {
    return events;
  }
}
2. In service.EventsResource, change the method associated with GET to:
   
   public EventsList get() {
        EventsList eventsList = new EventsList();
        List<Events> list  = PersistenceService.getInstance().createQuery("SELECT e FROM Events e").getResultList();
        for (Events e : list) {
            eventsList.add(e);
        }
        return eventsList;
}

   This will ensure that all the resource representations are returned instead of a reference to the resource. Make sure to fix the imports.

That's it, our server-side project is now ready. "http://localhost:8080/WebApplication3/resources/events" now return a complete RESTful representation of all the rows from the database table EVENTS.

Lets build the client-side application next. Make sure jMaki plug-in in NetBeans IDE is already installed.

1. In the NetBeans IDE, create a new Web project, enable "Ajax Framework" and choose the "Standard" layout for "index.jsp".  Lets say the project name is "WebApplication4".
2. Drag-and-drop a jMaki-wrapped Google Map widget in the 'Main Content Area' and jMaki-wrapped Yahoo Button in the 'Sidebar Content Here'.
3. Customise the widgets
1. Add id="mymap" attribute to the Google Map widget. The updated widget looks like as shown below:
   
   <a:widget  name="google.map" id="mymap"
         args="{ centerLat : 37.4041960114344,
                 centerLon : -122.008194923401 }" />

id="mymap" will allow the Map widget to be accessed by name later.
2. Add args="{label:'Plot Events'}" attribute to thes Yahoo button widget. The updated widget looks like as shown below:
   
   <a:widget name="yahoo.button" args="{label:'Plot Events'}"/>
4. In glue,js, add the following code to *onClick subscribe method:
   
   var url = jmaki.xhp + "?id=events";
var _map = jmaki.getWidget("mymap").map;
_map.setZoom(2);
_map.clearOverlays();
_map.enableInfoWindow();
   
jmaki.doAjax({method: "GET",
    url: url,
    callback: function(_req) {          
        var xmlobject = (new DOMParser()).parseFromString(_req.responseText, "text/xml");
        var root = xmlobject.getElementsByTagName('eventsList')[0];
        var events = root.getElementsByTagName('events');
        for (var i = 0 ; i < events.length ; i++) {
            var event = events[i];
            var eventName = event.getElementsByTagName('eventName')[0].firstChild.nodeValue;
            var venue = event.getElementsByTagName('venue')[0].firstChild.nodeValue;
            var blogs = event.getElementsByTagName('blogs')[0].firstChild.nodeValue;
            var dates = event.getElementsByTagName('dates')[0].firstChild.nodeValue;
            var id = event.getElementsByTagName('id')[0].firstChild.nodeValue;
               
            var encodedLocation = encodeURIComponent("location=" + venue);
            var url = jmaki.xhp + "?id=yahoogeocoder&urlparams=" + encodedLocation;
            jmaki.myHandler(url, eventName, blogs, dates, id, _map);
        }
    }
});
5. Add the following functions above the *onClick subscribe method:
   
   // "Function closure" used from http://econym.googlepages.com/basic1.htm
// Creates local copy of "marker" and "html" variables to be preserved for later use
function createMarker(point,html) {
    var marker = new GMarker(point);
    GEvent.addListener(marker, "click", function() {
        marker.openInfoWindowHtml(html);
    });
    return marker;
};

// Function closure that preserves "eventName", "blogs", "dates and "id"
// Gets the latitude/longitude from Yahoo Geocoding service and plots them on the map
// Also creates meaningful markers
jmaki.myHandler = function(_url, eventName, blogs, dates, id, _map) {
    jmaki.doAjax({url: _url,
        callback : function(req) {
            if (req.responseText.length > 0) {
                jmaki.log("name: " + eventName);
                var response = eval("(" + req.responseText + ")");
                var coordinates = response.coordinates;
                jmaki.publish("/jmaki/plotmap", coordinates);
                jmaki.log("plotting " + eventName);
                var latlng = new GLatLng(coordinates[0].latitude, coordinates[0].longitude);
               
                var blogHtml = "";
                b = blogs.split(', ');
                for (i=0; i<b.length; i++) {
                    blogHtml += '<a href="' + b[i] + '">' + (i+1) + '</a>';
                    if (i<b.length-1)
                        blogHtml += ", ";
                }
               
                var txt = '<table>' +
                '<tr><td>#' + id + ": " + eventName + '</td></tr>' +
                '<tr>Dates: ' + dates + ', 2007</td></tr>' +
                '<tr><td>Blogs: ' + blogHtml + '</td></tr>' +
                '</table>';
               
                var marker = createMarker(latlng, txt);
                _map.addOverlay(marker);
                marker.openInfoWindowHtml(txt);
            } else {
                jmaki.log("Failed to get coordinates for " + location );
            }
        }
    });   
};
6. Add the following entry in Web Pages, resources, xhp.json:
   
   ,
{"id": "events",
 "url":"http://localhost:8080/WebApplication3/resources/events/"
}
   
   assuming WebApplication3 is the project where RESTful Web service endpoint is hosted.

That completes our client-side web application as well. Now, either hit F6 (default key to Run the NetBeans project) and this will show http://localhost:8080/WebApplication4/index.jsp in the configured browser. Once you click on "Plot Events" button, all the markers on the Google Map are plotted.
Future Improvements

1. If Jersey can return all the resource representations directly, then the workaround used above may not be required.
2. Use e4x after <script type="text/javascript"> in index.jsp can be generated as <script type="text/javascript; e4x=1">.
3. Build the client-side application using Rails once issue #309 & #310 are resolved.
1. Once deployed as Rails application on WEBrick, create a WAR file and deploy on GlassFish.
2. Try this application using GlassFish v3 gem.
4. Embed Google Map in the blog entry.

An alternate title of this blog entry could've been "How I spent my winter break ?". But in order to keep the title inline with rest of other entries (keeping it simple and reflecting the content of the entry) I decided to use the existing title ;-)

Technorati: screencast conf jmaki jersey netbeans glassfish jpa javascript googlemaps restful web2.0 jmakimashups

Posted by Arun Gupta in web2.0  |  Comments[9]

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