Protovis-GWT 0.1 Released

Update: A newer version of Protovis-GWT has been released. Please see the wiki page for the latest information on Protovis-GWT.

Protovis-GWT is an open source GWT data visualization module. It wraps the Protovis JavaScript visualization API for usage in GWT. Protovis-GWT 0.1 (Download Module) is an early development version based on Protovis 3.2 and GWT 2.1. Several examples from the Protovis example gallery have been re-implemented using Protovis/GWT. Protovis-GWT is developed as part of the Choosel Visual Data Exploration Framework.

Version 0.1 implements the Protovis functionality for most conventional and custom examples from the Protovis website. The support for tree, graph and map visualizations as well as for interaction is still limited. Protovis-GWT currently supports Chrome, Firefox and Safari. IE is not yet supported.

Getting started with Protovis-GWT in your GWT project is easy:

1. Download the Protovis-GWT module jar file
2. Add the jar file to the build path of your GWT project
3. Inherit org.thechiselgroup.choosel.protovis.ProtovisGWT by adding <inherits name='org.thechiselgroup.choosel.protovis.ProtovisGWT'/> to your GWT module XML definition (.gwt.xml).
4. Use the Protovis Widget in your code, e.g.

public void onModuleLoad() {
  RootPanel.get().add(new ProtovisWidget() {
    protected void onAttach() {
      super.onAttach();
      initPVPanel();
      // create visualization here...
      getPVPanel().render();
    }
  });
}

More information on Protovis-GWT:

• Wiki Page
• Example Visualizations
• Source Code

Generic JavaScript Array for GWT objects

GWT supports several wrappers for JavaScript arrays, e.g. JsArray, JsArrayNumber and JsArrayInteger. However, they all require JavaScript primitives or JavaScriptObjects. I needed to pass a JavaScript array containing regular GWT objects to a third party JavaScript library, together with a callback function that resolves specific properties for elements in the array. The skeleton of the array is similar to the JsArray classes provided by GWT (full source code):

import com.google.gwt.core.client.JavaScriptObject;

public class JsGenericArray<T> extends JavaScriptObject {

  // typical JsArray methods

}

I initially tried to use this array with the following factory method:

  public static native <T> JsGenericArray<T> createGenericArray() /*-{
    return [];
  }-*/;

However, I ran into the problem that instanceof Array tests on this array in the 3rd party libraries returned false (as debugging showed). This is because GWT runs in an iframe and instanceof does not work across frames. One recommended solution is duck typing, but this was not an option because I did not want to change the 3rd party JavaScript library. To address this issue, I changed the factory method to return an array object from the main frame in which the JavaScript libraries run:

    public static native <T> JsGenericArray<T> createGenericArray() /*-{
        return new $wnd.Array();
    }-*/;

This approach worked with Firefox 3.6 and Chrome 9, but not with Safari (see Webkit Bug 17250). However, I am not a JavaScript expert and would appreciate any feedback on potential shortcomings of this solution, especially concerning cross-browser compatibility.

Slides of InfoVis 2010 presentation "How Information Visualization Novices Construct Visualizations"

I presented the paper "How Information Visualization Novices Construct Visualizations" at IEEE InfoVis 2010 in Salt Lake City. Here are my slides:

Choosel at VisWeek 2010 and at CASCON 2010

Interested in data visualization on the web? There are several Choosel-related events at VisWeek 2010, CSER and CASCON 2010. Choosel is an open-source framework for browser-based data visualization.

Watch video in full screen and HD for better quality

Oct 24-28, I will present the InfoVis poster "Choosel – Web-based Visualization Construction and Coordination for Information Visualization Novices" at VisWeek 2010. Here is a preview:

Oct 31st, there will be a presentation on Choosel and the Work Item Explorer at CSER. The Work Item Explorer (developed by Patrick Gorman, Del Myers and Christoph Treude) is a research prototype built on Choosel that facilitates the flexible, iterative exploration of Jazz data, focusing primarily on work items.

Nov 1-4, there will be CASCON exhibits on Choosel and the Work Item Explorer. The Choosel exhibit (Bradley Blashko, Lars Grammel) will be at booth X2 near the Central Tower, and the Work Item Explorer exhibit (Patrick Gorman, Christoph Treude) will be at booth U5. The exhibits are open 5pm to 7pm on Monday (Nov 1), from 8.30am to 7pm on Tuesday and Wednesday (Nov 2 and 3), and from 8.30am to 1pm on Thursday (Nov 4).

Attracting the Community’s Many Eyes: an Exploration of User Involvement in Issue Tracking

User input drives the development of software systems by contributing ideas, reporting bugs and clarifiying requirements. To encourage such feedback, open source projects often provide issue tracking systems (e.g. Bugzilla) that are open to the public. In commercial software development, however, this is often not the case. I was interested if opening issue tracking systems of commercial projects to the public would yield similar community input as is the case for open source projects. Together with Holger Schackmann, Adrian Schröter, Christoph Treude and Margaret-Anne Storey, I studied community involvement in issue tracking in the Eclipse and IBM Jazz projects. IBM Jazz is a commercial IDE for collaborative development. The Jazz project has opened its issue tracking system to the Jazz community. Eclipse is a well-known open source IDE with a public issue tracking system.

Our 8 page research paper "Attracting the Community’s Many Eyes: an Exploration of User Involvement in Issue Tracking" was accepted at HAoSE 2010, the Second Workshop on Human Aspects of Software Engineering, co-located with SPLASH 2010. Here is the abstract of our paper:

A community of users who report bugs and request features provides valuable feedback that can be used in product development. Many open source projects provide publicly accessible issue trackers to facilitate such feedback. We compare the community involvement in issue tracker usage between the open source project Eclipse and the closed source project IBM Jazz to evaluate if publicly accessible issue trackers work as well in closed source projects. We find that IBM Jazz successfully receives user feedback through this channel. We then explore the differences in work item processing in IBM Jazz between team members, project members and externals. We conclude that making public issue trackers available in closed source projects is a useful approach for eliciting feedback from the community, but that work items created by team members are processed differently from work items created by project members and externals.

Download Paper