322 Patterns: Pervasive and Rich Device Access Solutions
speak as naturally as possible to the system. However, it is also true that users
find a form-filling approach quite effective because it makes it clear what needs
to be done. However, for a grammar/menu approach the number of fields needs
to be limited to maintain user satisfaction.
In the present requirements, because the queries to the caller can be well
structured (“where do you want to leave from?”), and there are only three
queries, ITSO Railways has decided on the basis of cost benefit to implement a
grammar-based approach. However, it recognizes that once the system is in
place it could easily collect the required data for the SLM (by initially prompting
the caller with “Just ...