LabVIEW Idea Exchange

The web format wars are over, and the plug-ins have lost.  Microsoft has relented and will support HTML5 and SVG in IE9, and has admitted that Silverlight's role will change to that of a Windows phone development platform.  Silverlight support on iPhone/iPad/Andoid/Chrome OS will likely never be fully formed, and will wither on the vine. 

New javascript/ecmascript engines that are much faster, and make use of multicore environments have arrived and work well.  The addiition of WebSockets means your browser can now open a tcp/ip socket.  I have done this, as I am sure others have, as well.  Drop an old-fashioned tcp/ip listener into your diagram, return the WebSocket handshake, and presto: you can now stream data directly to/from your browser.  WebSockets provides an "onmessage" event handler function which you can define.  Combine this with the SVG DOM, and you can transform SVG elements until your heart is content.  Two-way streaming of data between your browser and plain-old tcp/ip?  Goodbye web services, we knew you well. Good riddance, plugins.

I have built my own SVG UI objects using Inkscape (free), and wrote a script (notepad/Inkscape script editor, also free) to handle WebSockets communication without a gateway.  I have a simple LV class built on the TCP/IP functions that will stream data to/from a browser which is pointing to an SVG "webpanel" that I also built using Inkscape.  So far I have a simple waveform graph, buttons, LED's, progress bars, etc.  I have tested my Inkscape webpanels in Firefox 4.0 Beta and Google Chrome 9 and it works like a champ, and is very fast.  The old-fashioned LV webserver will serve up SVG files with the addition of a mime type. 

An alternative to SVG is the HTML5 <canvas> tag, which allows the rendering of graphics drawn using java/ecma script.  There is a free-for-personal-use script library called RGraph Library that you can download with lots of example code.  Here is RGraph/LabVIEW in action in Chrome 9:

So what is my idea?  

0. Ditch Silverlight.

1. Convert all of the nice-looking UI panel objects in the Web UI Builder from Microsoft XAML to SVG and distribute them with the  LabVIEW professional development license.  I am programmer first, and I admit my web panel objects don't look too good.

2. Design a script library for handling WebSockets communcation (or add native support for WebSockets to the Shared Variable Engine) and manipulating/updating the SVG UI objects from streamed WebSockets data.  Make this library open source.

3. Create a standard open protocol for streaming LabVIEW data that sits on top of WebSockets and is free and open.

4. Publish documentation for the SVG UI elements so users and thrid parties can create new UI objects.  Make use of the creativity of the community at large!

5. Modernize the Web Publishing Tool so that it will optionally output an HTML5 and/or SVG document that accepts streaming I/O from WebSockets.  The user could choose from compatible SVG elements to use in place of front panel elements on the VI being published.

6. Create a Web UI SVG element exchange for registered NI users to upload/download elements for free.

7.  Work toward the long term goal of adding SVG Import/Export to the control editor (with better editing tools), or make the CTL format of custom controls SVG/XML.

I sometimes delete controls from the BD and realise some time (from milliseconds to minutes) that I have some broken local variables.

I get greeted by the hugely informative imagery as shown below:

Yeah, good luck realising what exactly you deleted by mistake.  No name, no way of finding out what the local PREVIOUSLY linked to.

I suggest retaining at least the name of the Control / Indicator the local was linked to so that the poor programmer (me) has some fighting change of undoing the error.  Bear in mind there could be many changes made to a VI before this kind of thing is notices so a simply "undo" fix could end up being VERY awkward indeed.

An example of how this could look:

Here I at least know WHAT I have deleted by mistake.

On a For Loop that is configured to have parallel iterations there is a nifty feature when using errors on a shift register.  This feature is explained in an article here.  It basically ensures that For Loops that run 0 times, will preserve the incoming error as if the tunnel was a shift register.  However this feature also means that errors from iteration 0, won't be passed into iteration 1.  What is returned if the loop runs 0 times is just the incoming error.  But if it runs for more than that, the errors are all merged and returned will be the first error seen.

This idea is just to allow this already existing feature to work on non-parallel configured For Loops.  When would this be useful?  Say I want to delete an array of files.  I want to attempt to delete all files, even if there is an error in trying to delete some, just keep trying to delete the other files.  Initially you may think this:

But that has the clear problem that if the incoming array is empty, then the error will be cleared.  So we often do something like this.

And honestly this bit of code isn't that big of a deal, but this feature already exists.  However it only works on For Loops that are configured to run iterations in parallel.  In this case I might be attempting to delete files in a specific order due to their placement on disk, and running in parallel isn't what I want.

Since not everyone wants all errors in loops to act this way it would need to be a right click menu to turn the tunnel into a normal one, a shift registered one, or a preserve and merge one.

That is what I want.