I thank Marcin Warpechowski, for creating this wonderful library. The community around this is very helpful and this library is rapidly evolving into an even better library!
What my solution involvedMy project that I was implementing handsontable was a classic example of Web Forms with PostBack and code behind access of form elements directly.
How to save the dataI did not try to create a Web Form custom element, instead I just took advantage of what was already implemented. I started out with creating everything I needed to render a blank handsontable to my page where I was replacing this old control. You can get that from the handsontable demo pages.
I then added the JSON2 library, from Douglas Crockford's Github repository, to my project and included it in the page that the table is on.
Lastly, I used jQuery to bind an event on the form submission that ran a simple verification that there were no invalid cells in my table. If my table was completely valid, then the event would harvest the data from handsontable and with JSON2 serialize that data into a valid JSON string and save it into a hidden field that my code-behind would pick up. Once it is on the server you can do what you need to do to this.
How to retrieve the dataWith Web Forms and the page I was working with, I needed to be able to repopulate the table with data that had traveled across my PostBack event. So just as I did with my form submission event, I wrote a specialized page load event that populated an object for my handsontable to use during it's creation.
My event just listens for the ready event of the page and then looks for that hidden field I created to save the data. It pulls the data out of the hidden field and uses JSON2 to deserialize the object out of the string and that result is passed to my handsontable create table method.