How to Access / Run Google Apps Script (GAS) Functions from ordinary non-GAS web apps?

Question

This is an alternate to the Google Maps V3 Full Integration API issue in my previous question.

I would like to give the user the ability to click a button, that then creates a new Google Spreadsheet, within their Google Drive, that allows them to save the data (JSON) that has been created while playing with my Mapping Application, into the new spreadsheet.

Later, the user can go to their Google Drive, open the spreadsheet, click a menu, open and populate my Maps App with their data from the spreadsheet. The user can edit the data either in the Spreadsheet or the Map and the changes go both ways.

Basically, I am looking for two way data binding between Google Maps V3 API and Google Spreadsheet that is very easy for a non-technical user.

It would seem that I should be able to write a GAS function and access it from my standard web page. How do you do that?

If I could convert my Maps V3 API app to GAS, the issues would be trivial, but until then an alternate workflow between Maps and Google Drive would be very helpful to allow users to save / collaborate their work.

Answer 1

If you deploy your Apps Script project as a web app you can have your application make requests to it over HTTP. The doGet() and doPost() handlers can both read request parameters, and using the ContentService you can return JSON or XML data. Likewise, inside Apps Script you can use UrlFetchApp to make HTTP requests to your application.