Direction+

I am working on a web app, Direction+, running on Google App Engine for Java. Yes, it is another direction service that suggests a driving route based on your chosen source and destination. But it has some add-on features as its name suggests: Direction Plus.

First, you can personalise Direction+ by providing your car's information, in particular, the fuel consumption measurement of your car, for urban cycle, extra-urban cycle and combined cycle. Thus, when calculating the route, Direction+ is also able to calculate how much fuel you will use and how much it costs (based on the fuel price you set). The fuel consumption calculation is measured on each individual step of the route. For instance, driving on a motor way will be much more fuel-efficient than driving in the city center. Isn't it good to know the cost of the driving before hand? In addition, the calculation is done in your own browser and your personalisation is stored in your browser as a cookie. So there is no privacy concern at all.

Second, Direction+ is a mashup that combines Google Maps Service and BBC travel news service together. When a driving route is calculated, the travel news, e. g., accidents news, along the route are displayed as well on the map. Isn't it good to know the traffic situation before driving? Currently too many travel news are returned especially when the route is very long, efforts are being made to improve the algorithm of filtering the not-so-relevant news.

How quick is Direction+ updated with BBC travel news? Please see its status page. A complete update takes about 30 minutes. For instance, at the time of writing, the last update took 26 minutes to finish. It read 2297 news from BBC, among which only 50 happened after the previous update, and among the 50 news that newly happened, 12 have cached coordinate in the data store. So though the number of news is large, Direction+ manages to reduce the communication to a small amount.

One of the tricky things about GAE for java is that every servlet request must be served within 30 seconds. So the update of news is implemented in an incremental and on-the-fly way:

• Incremental: the complete update is divided into many small steps, and each step can be finished in a controlled time slot;
• On-the-fly: the news updated in each small step is available immediately, long before the complete update is done.

Direction+ is designed for UK users because I live in UK. Enjoy it and let me know what you think!

Browser Application

I am working on a browser application, which I already made some good progress and will put online after it is refactored in object oriented JavaScript.

What I called browser application should have the following three characteristics.

1. A browser application's runtime environment consists of a web browser and internet only. So if you can surf the net, you can run it. Of course nothing prevents it from being deployed on a web server for people to access. Note. in that case, the web server is not required to have any extra support except static HTTP hosting.
2. A browser application uses AJAX to provide functionalities. With so many powerful AJAX APIs around on the internet, a browser application can have some amazing functionalities.
   
3. A browser application can easily be a rich internet application given that now JavaScript, as well as other client side technologies, have already become so rich in terms of presentation capability.

In summary, a browser application is a browser (only) based rich internet application using AJAX.

Use Eclipse RAP to Build Rich Internet Application

It is a pity that I had not heard of Eclipse RAP (Rich Ajax Platform) when last year I developed Grimoires Browser, an Eclipse RCP based client for the Grimoires Service Registry.

RAP has joined the family of Eclipse UI toolkits, as existing ones such as SWT for Windows, SWT for Liunx, and SWT for Mac. In some sense, RAP can be considered as SWT for Web.

RAP is ued to develop Rich Internet Application (RIA). To develop an RAP-based web application, programmers are still working in Java, in SWT, and in JFace. And RAP makes sure the UI is built on top of HTML, JavaScript and Ajax. Remind you something? Yes, GWT. There are some very good introductory articles [1, 2] about RAP on IBM Developer Works.

It is claimed that in a minimal effort, we can transform an existing RCP application to RAP; or we can even build an application which is largely independent of RAP or RCP. So it can run as both a web application and a desktop application.

No doubt, RAP is the way to go to make Grimoires Browser a web application. It will then totally relieve users the pain to install some software on their machine in order to access Grimoires.

Yahoo User Interface

Programming in JavaScript was very painful. You have to make sure your code is compatible with all major browsers such as IE and Firefox. Now thanks to well-developed JavaScript libraries, JavaScript programming is much more pleasant.

JavaScript libraries, such as Yahoo User Interface (YUI), jQuery, Dynamic Drive, and Dojo, not only deal with cross browser compatibility issues, but also make common tasks easy.

I have used several components of YUI in developing the OMII-UK website:

• CSS Reset (neutralizes browser CSS styles)
• CSS Base (applies consistent style foundation for common elements)
• CSS Fonts (foundation for typography and font-sizing)
• CSS Grids (page layout)
• The YAHOO Global Object (base requirement for all YUI components)
• DOM Collection (convenience methods for DOM interactions)
• Event Utility (event normalization and custom events)
• Button
• TabView

BTW, browsershots.org allows you to see how your website looks like in tens of browsers.