Back to Volta

Today I took the afternoon to take another look at Windows Live Labs Volta.

The idea of deferring the application partitioning to the last minute may be good for some types of projects but translating “X” (IL in this case) into JavaScript was something I’ve been wanting since the ASP + VB6 days!

I always thought that writing code in general and data validation code in particular for the server and then for the client was a tedious and error prone task.

At those days I had to write validation code in VB6 for the server and then rewrite it again in JavaScript for the client. Besides being tedious, it is an error prone task because you had two places to maintain the code as validation logic evolved.

Today I decided to test this with some legacy code I have here. I was thinking on getting some document number validation code I have here, but I stumbled across a function that translates currency amounts into their textual equivalents. Not sure how to say this in English, but the idea is to translate “1,234.56” into “Um mil, duzentos e trinta e quarto Reais e cinquenta e seis centavos”. That is “One thousand, two hundred and thirty four Reais and fifty six cents” in Portuguese.

I got this code originally written in Clipper from a magazine back in 1993.

Sometime later I rewrote it in Access Basic 2.0. A couple of years later ported it to Access 97’s VBA and at last VB 6. I have not touched it since 2000.

I ran the project through Visual Studio 2008 VB project Converter, made a couple of tweaks (really!), and added the project to my Volta test solution configured to run in Debug mode and voila! It worked like a breeze!

The important part is that I converted the project to a normal VB Class Library. Not a Volta Class Library. That implicates that I could theoretically use any any library that does not have dependencies on anything not supported by Volta and have it flow as JavaScript to the client side.

That must be what Erik Meijer means when he says "Volta stretches the .NET platform to cover the Cloud.”!!

It is important to notice however, that when you run the code in Debug mode, you are really running the IL version of it. I’m not yet sure how the magic works. Give me time!

As soon I tried to run it in Release mode, the page started complaining about unsupported features such as the Decimal constructor that accepts a Double or somewhere in the VB string helper functions trying to get a CultureInfo.

This is comprehensible since the technology is in its very early stages.

I tried equivalent BCL types and members without using the Visual Basic helper functions, and they worked so as soon as I find more time, I’ll try to fix it. I could simply try to isolate the helper functions giving me trouble and fix those pieces of code, but I’m more inclined to rewrite it in C# since it is not too much code and I have not been programming seriously in VB since 2005.

Anyway I’ll decide the route another time.

Stay tuned!


I just watched the Channel 9’s two part video with the Volta team and I have to say that it was mind blowing.

Volta has some really interesting ideas on how to simplify the development of distributed applications.

On the second part they get into the details of some of the obstacles they found translating IL into JavaScript such as JavaScript’s lack of a goto statement and how they got around it: using a while loop and a switch statement – a trick much like what C# does to implement “yield return”.

Other interesting thing was how they used exceptions to simulate multi-threading within the browser.

Really cool stuff worth watching!

The link below points to a post on the Volta Team Blog on Microsoft Live Labs which points to the Channel 9 videos. You also be able to get to the rest of the blog from there.