After we have built an index, we can start creating our grammar file. This specifies what natural language the service can understand, and how it can translate into semantic query expressions. Open the academic.xml file to see an example of how a grammar file can look.

The grammar is based on a W3C standard for speech recognition, called SRGS. The top-level element is the grammar element. This requires a root attribute to specify the root rule, which is the starting point of the grammar.

To allow attribute references, we add the import element. This needs to be a child of the grammar element, and should come before anything else. It contains two required attributes: the name of the schema file to import, and a name that elements can use for referencing the schema. Note that the schema file must be in the same folder as the grammar file.

Next in line is the rule element. This defines a structural unit, which specifies what query expressions the service can interpret...