A C# SDK for the LUIS, Microsoft's Language Understanding Intelligent Service API is now available on GitHub, taking us another step forward towards being able to build bots that respond to natural, spoken language.

Satya Nadella unveiled his vision for Conversation as A Platform at Build 2016 at the end of March. The idea is that human language becomes the user interface and our future apps will combines the role of chatbot with that of IFTTT recipes to respond to queries and instructions in an intelligent way. All this rests on Microsoft Cognitive Services, in particular Language Understanding Intelligent Service (LUIS), which is a cloud service for language understanding that provides intent classification and entity extraction and brings machine learning to your apps.

This video introduces LUIS and how to use its API:

The documentation provides this overview:

LUIS is designed to enable you to quickly deploy an HTTP endpoint that will take the sentences you send it and interpret them in terms of the intention they convey and the key entities that are present. By using the LUIS web interface, you can custom design a set of intentions and entities that are relevant to your application, then let LUIS guide you through the process of building a language understanding system. 

Once your application is deployed and traffic starts to flow into the system, LUIS uses active learning to improve itself. In the active learning process, LUIS identifies the interactions that it is relatively unsure of, and asks you to label them according to intent and entities.

The SDK, which can be cloned from GitHub and, like other Microsoft Cognitive Service APIs is licensed with the MIT License, can be used in two ways: 

• use the client directly and call the functions "Predict" and "reply" that are present in the "LuisClient"
  
  
• create handlers for each intent and setup a router using these handlers in order to have the router handle the responses instead of doing so within the client application.

It comes with a dummy application that provides a very brief tutorial to how to use the service but to get further and to use the Cortana pre-built apps in English, Chinese, French, Spanish and Italian you need to upload your own app. 

The sample application allows you to perform the Predict and Reply operations and to view the following parts of the parsed response: 

• Query
• Top Intent
• Dialog prompt/status
• Entities

LUIS is currently in beta and is free to use, although the number of free monthly LUIS transactions is changing from 100,000 to 10,000 transactions effective September 4, 2016.