IVR-style dialog system / workflow / menu

Question

I need to build a dialog system similar to IVR used in call centers. My system is not phone-based, but the dialog is similar. Something like

System: "Main menu: Enter [1] for menu1, [2] for menu2"
User: [1]
System: "menu1: enter [1] for apples, [2] for oranges, [3] for main menu"
User: [7]
System: "What??"
System: "menu1: enter [1] for apples, [2] for oranges, [3] for main menu"
User: [2]
    ... and so on

I want to have a nice declarative description of all the possible options and a nice way to run through that tree, guided by user input.

Already considered: ANTLR-generated lexer/parser (seems to be an overkill), SCXML-based state machine (seems like only transitions can be declared, the rest needs to be coded)

Answer 1

I've never seen SCXML before, but after a short glimpse on the project pages and the examples, it looks to me like it has everything you need. Your IVR can be modeled as a state diagram. Entering a state either presents the next choices or starts an activity (while presenting the next menu level is an activity too).

It might be tricky to implement a 'wrong user input' state (or SCXML already has a solution for this common task).

You could invent a small DSL to simplify editing this statemachine. Documents written in this DSL would be translated to SCXML files that would drive the IVR system.

(thanks for the SCXML pointer!)