1. A computer program product, tangibly embodied in an information carrier, the computer program product being operable to cause data processing apparatus to perform operations comprising: receiving a first request from a client application for first speech animation, the first request identifying data to be used to generate the first speech animation, wherein the identified data includes a tag having a parameter corresponding to a desired emotion and a reference to an application scenario of the requesting client application, the application scenario corresponding to a behavioral context that includes a set of expressions that are appropriate to the particular application scenario; determining which application scenario prompted the first request based on other data information included in the first request; retrieving the data and the set of expressions in the behavioral context; generating the first speech animation based on the parameter and using the retrieved data and the set of expressions in the behavioral context; and sending a response identifying the generated first speech animation to the client application.