I developed for my PhD thesis a Java-based software toolkit called OpenDial, which is released under an MIT open-source license. The toolkit is available at the following address:
OpenDial is a Java-based, domain-independent toolkit for developing spoken dialogue systems. The primary focus of OpenDial is on dialogue management, but OpenDial can also be used to build full-fledged, end-to-end dialogue systems, integrating e.g. speech recognition, language understanding, generation, speech synthesis, multimodal processing and situation awareness. The representation of dialogue domains is based on probabilistic rules encoded in a simple XML format, allowing dialogue developers to combine the benefits of logical and statistical approaches to dialogue modelling within a single, unified framework.
In addition to the download packages, the OpenDial website also includes some practical examples of dialogue domains and a step-by-step documentation on how to use the toolkit.