Archive for the ‘Flare’ Category

First Visual

Thursday, June 26th, 2008

After many hours of trying to get Moodle and Flex with Flare to play nice, i finally have been able to get a simple visualization working using the grade book data from Moodle.


The first visual is a scatter plot of Normalized Grades vs Students. The different colors represent different items that have grades associated with them and the different shapes are the groups/sections the students are in. It’s not much to show for UI or labeling of the chart yet but provides a starting point to make the report/visual plug-in and has gotten me on my way learning the Flare API.

Hopefully i will have some more polished visuals and UI to show off in the coming weeks.

I Can Haz Data?

Monday, June 23rd, 2008

Image from anomalous4's photostream on flickrI am currently in the process of getting grade data to be shared between Moodle and Adobe Flex with Flare in a secure and elegent way.

Flare has some nice built in functions for loading data from a url that is either in a tab or json format, witch would normally work great except the data in question consists of students grades and statistics relating to them witch can not be publicly shown and is protected by Moodle’s capability system. This means that Flare can not simply load a page that outputs the data in tab or JSON format as it would not have the session or cookie that the browser does to let Moodle know that you have the capability to access the data so it just gets the HTML for an error page.

Passing a user name and password (or hash there of) between the Flash Player and the web server are out of the question for security reasons and embedding all the data needed to generate the visualizations in the Flash variables or JavaScript becomes ugly fast and could break down in the cases of very large sets of data (there is a limit to the length of a Flash variable passed from HTML). There also is no way i know of to share a browsers cookies with Flash and then the sites it calls on (and if there is it would mean recoding how the Flare DataSource class works).

The solution? Well the method i am country working on is passing the session name and id from Moodle to Adobe Flex/Flash (threw the Flash variables embedded in the HTML generated by PHP) and then using the Flare DataSource class to load the URI of the JSON formated data with the course id, session name, session id and graph/visualization type appended to it. Hopefully this method will work like how cookieless sessions do in Moodle where the session information is appended to the URI and Moodle will see the request as if it came from the user them self, with the correct capabilities.

My only concern with this method is if a teacher or student where to save the HTML of the page and send it to some one it would contain there session information. In theory this information could be used to access the account that is tied to the session and the attacker could then change the password for the account to take it over. However this would only be possible for the period of time when the session is valid and would be just as insure as Cookieless sessions all ready are in Moodle (in terms of a user copy and pasting there URI with the session id in it) and a user would have to willingly give a copy of the HTML to the attacker.

If all goes well i will have a simple demo of this before the end of the week that can show a simple graph of grades using Flare.

Adobe Flex + Flare

Thursday, June 19th, 2008

box_flexbuilderstandard3_150×150.jpgNow that the report/stats plug-in has a release out i have started geting Adobe Flex and Flare set up for the report/visual plug-in.

The first issue i ran into is that i could not find a copy of Adobe Flex Builder or the Eclipse plug-in for a Unix/Linux based operating system witch i am using for development. There site seems to only list versions for Mac and Window even tho flex is sposted to be cross platform. After some time searching tho i was able to find an alpha version of Adobe Flex Builder for Linux from Adobe Labs.

Another issue that may come up for students is the cost of Adobe Flex Builder, normally it is priced at $249 for the standard version and $699 for the professional version but there is a time base trial version that can be used for 60 days. luckily for students and other persons in education institutions, Adobe offerers a free educational version with proof of enrollment. I have applied for the educational license but i can take up to two weeks for them to e-mail you with the key so in till then i will be using the trial version. There is a stand alone Flex SDK that is free and lets you use any IDE you like witch would also solve both theses issues but is apparently more complexed to use and has less features.

The next step in setting up Flex was the installing process. For Linux the installer comes in the forum of a bin file witch you can execute by typing “sh filename.bin” in the console. If done correctly a GUI based installer will pop up and guide you threw the install process. Unfortunately this step was not totally strait foreword as one of the requirements is Eclipse 3.3 when the package system i am using still lists 3.3 as unstable. So i had to remove the mask on version 3.3 and all a bunch of it’s dependency to updated to the new version.flare-logo.gif

Now to add in flare, i had to download the prefuse flare libraries and unzip them in to my workspace directory and with that Adobe Flex and Flare should be installed on my Linux laptop and ready for development. In my next post i hope to talk about getting started with flare and talk about the start of the report/visual plug-in.

As for report/stats, i have added a printer friendly version and option to invert the statistics table to report/stats witch can be seen on the demo site, this lets users have the table extend downwards rather then width wise so the report will fix on there screens and be easier to print.