Playing with Google Visualization Query

Since a month has passed, this week is the last week before our first milestone. During this week, we re-organized the SVN repository. Also we updated our Google Project Hosting page. Further more, we improved our existing stoplight gadget a little bit and release the version 1.3.

Among these tasks, I worked on improving the stoplight gadget. For the new version of stoplight gadget, users can specify if they want auto-refresh in their gadget. To implement this functionality, I just create a new user input and pass the value to the Google Visualization Query default method setRefreshInterval. The second enhancement is that user can specify a message source URL in the gadget. This message source URL should contain the relevant message about the data from the data source URL. Hopefully, this message can help user better understand the stoplight and the data. This functionality requires to send another Google Query in the gadget. To figure this out, I had a lot of fun in studying the Google Visualization Query.

Initially, I was trying to nest the Google Query together, which looks like:

MainMethod{
  ...
  ...
  queryA.send(handleQA)
}

handleQA(response){
  ...
  ...
  queryB.send(handleQB)
}

handleQB(response){ 
  ...
  ...
}

However, I found that handleQB is never invoked. Then I start Googling this problem. Most post said it is because the request ID for two query.send are the same, so the query.response will confuse which request should response to. However, it is not a really good idea to manually set the request ID, since handling the response requires modifying the server side which is kind of pain in the ass. After couple days thinking, I just realized this actually is not very hard. I simply moved the code a little bit. So the code looks like:

MainMethod{
  ...
  ...
  queryA.send(handleQA)
  queryB.send(handleQB)
}

handleQA(response){
  ...
  ...
}

handleQB(response){ 
  ...
  ...
}

Yes, it is very simple. So it seems Google Visualization Query does not like get nested. Anyway, I am very surprised that some tasks look so hard, but we soon can figure out how easy they are if we take another perspective.

Well, here is a link for the Stoplight Gadget 1.3. I am looking forward to the upcoming enhancement of this project.