Flex will be supported for 2 more years. However, I am currently looking into Geocortex as a middleware. When ArcGIS 10.3 is released it will have a web app builder bundled in for you to use. I would wait until SP1 to migrate. Everything moving forward looks like HTML5 and Javascript. That's all I've seen/heard so far.
It's just that Flex is free. Geocortex, not so much.
Have you heard any ETA on 10.3? I've heard about the web builder, too, but I don't want to wait! 😃
Joanna,
I would go in the Javascript API direction. It is free and works across a lot of platforms!
Check it out: ArcGIS API for JavaScript
Tim
Joanna,
It's seems like Esri answered our prayers: the configurable HTML5/JavaScript-based application is on its way (see Web AppBuilder for ArcGIS)!
JavaScript for sure. Then you can Use REST API via AJAX and hopefully, one day, WebSockets!
If you are starting a new site and have no legacy apps then definitely go with HTML/JavaScript.
Awesome - thanks, all!
Thanks all. Probably using the HTML builder for now. I'm interested in the JavaScript option but I wan tto host on AGO not create a separate web server.