VOXI, the VSys One eXchange Interface, provides an API to the business logic and data stored in VSys; it serves as the data access and business logic layer for VSys Live and for the Community Partner Portal. All communication with VOXI is done using XML over HTTP.
Organizations who wish to extend VSys One by designing their own web interfaces or integration tools can license VOXI for that purpose. (Users of VSys Live have a license to use VOXI solely for VSys Live.) The VOXI API's full documentation is available under non-disclosure, but a summary and subset of its interface can be downloaded here.
VOXI is a multithreaded application built with the same code as VSys One. This allows changes and enhancements made to these applications to be trivially available to VOXI and the tools which call it.
External applications do not need, or in general want, to directly access the data tables use by VSys One and VOXI. Unless otherwise indicated, the data stored in these tables is not documented nor intended for direct access. Where it is documented, it may be used for querying but not updating or deleting.
VOXI is essentially stateless: all information that it carries is posted to the database immediately, and little information is cached between requests. This means that you can have a farm of VOXI instances running on different machines, all essentially identical and returning the same data.
You can download a sample of the VOXI API documentation here; the full documentation is available only under NDA.