Implementing interaction between jQplot and java servlets

Today I'm going to share my experiences developing a way to let users plot graphs of certain interesting data.


Way back when, we originally were going with the Google chart API to accomplish this. It's simple and it looks good. However, we decided instead to take a jQuery approach (for learning and to avoid making a call to a second server) with jqPlot. jqPlot is a free graphing library which generates the graph on the client side and accepts data in a convenient format.

After playing around with it, we were able to develop a nice implementation:

Now aside from a few things that need to be worked out (such as fractional years), it looks good and was very simple to implement. Our approach to this using java servlets was:

• Client sends an AJAX graph query to the GraphsController class with a parameter ("getgraph") set to true to signify a graph request
• Servlet gets request, builds a GraphRequestBean and validates it. If validation fails the server sends back an error object using the JSON library for Java called google-gson. 
• Servlet sends request to a GraphsManager, which generates the Graph by interacting with the data layer. 
• Graph is sent as a JSON object and is read by the javascript, where a call to the plotting library is made. 
• User gets nice looking graph

 We also added some error handling and the ability for users to regenerate the graph through a link. I'm pretty excited about this implementation (and jQuery in general...) because it worked very well. And also I have even more respect for unit tests because they saved a lot of time debugging, since I was constantly changing code around while developing.