Have fun with ARINC 661, XUL, Javascript, beanshell, and Java

One of my project is a Client-Server ARINC 661 framework which use a lot of socket-bound activity from the Client (called User Application in the standard, it handles the logic here) to the Server (which perform the graphic rendering).

The communication protocol in ARINC 661 is specific and a bit complex (no SOAP, no REST, no CORBA, not RMI, but purely specific binary messages on top of the lower-level bus-level layer protocol). So to ease development of Java clients, I developed a generic API to handle this.

I thought it could be cool to allow users to prototype the logic of the Client. Using beanshell for this was the logic thing to do (pardon the pun), because it is very close to Java, so transcoding from beanshell to Java is straigthforward.

The second step was to be able to add scripted control panels for the Client. I don't want to recreate the wheel, so I decided for the use of XUL. One cool side-effect is that users would be able to debug their scripts using Firefox.

OK, it's one thing to create control panels in Java by parsing XUL scripts, but if you are not able to wire the widgets commands to the logic, it's no use. I decided for using Javascript (by using Rhino). Then I had to wire beanshell methods to Javascript. It involved a bit of code to be able to do that, but it was possible.

But getting or setting widget attributes at the Javascript level is also mandatory ! With some amount of work (in fact not a lot of work, I only had to use the right approach to do it), it was also possible.

So basically now I have a framework where I can script ARINC 661 logic in beanshell, and wire these scripts to commands in XUL declarative files. I have a purely scripted ARINC 661 Client.

In this process, I found that Rhino is really a very good Javascript engine, but that there is few informations or tutorials when you have to perform specific things like I had to do (hmm, it's no so specific). I will blog about what I discovered about Rhino specificities in some days (there's not much to say about beanshell / Java, it just work, but as it is so close to Java, there's no surprise). I thing it can be useful to others.