@Carl Love Yes, the bar itself represents the sum of all text, photos and links in one month.

Example: 10/2012 has 13 "actions". 6 Photos (the purple part of the bar), 4 text (yellow part) and 3 links (green part).

I have the data as JSON. I can put it in whatever I want.. a list, a matrix, an array. I put it in the Matrix because I thought this would be right format.

@Carl Love text1 is just a type, like text, photo or link. this type is represented in the plot as green = text, yellow = photo and purple = link. I think I could replace this with text = 1, photo = 2 etc.

The timestamp is defined as ISO 8601. YYYY-MM-DDThh:mm:ss+Timezone. I think it should be always +0000 but even if it isn't, the time doesn't have to be precise to the hour, because the plot normaly stretches over a time of a few months.

And yes, you are right, in this example each bar represents one month, but I was hoping Maple can adjust the time scale depending on the number of datasets.

This example is from the facebook analysis of wolframalpha. I'm trying to duplicate a few features for a study project using OpenMaple and JavaEE instead of Mathematica.