overview (1K)

The Vista DAOs
The DaoFactory can create two kinds of DAO, one for a single site and one for multiple sites. When the protocol is VISTA this results in VistaDAO and VistaMultiSiteDAO.

VistaDAO
To interact with Vista, this DAO uses methods derived from the Delphi RPC Broker. At some point, this will change to using VistaLink. Like the Delphi broker, therefore, the VistaDAO connects to port 9200 unless otherwise directed by the configurations in the XML site file. The DAO authenticates with VistA by using the user's access and verify codes. Then the OR CPRS GUI CHART context must be set or no RPCs can be made. So the user must have CPRS access.

VistaMultiSiteDAO
With this DAO, client software can acquire data from any site in VHA. This is accomplished with an array of VistaDAOs, one per data source. The first DAO in the array is the one associated with the site at which the patient was selected. If this site is the same site at which the user logged in, this DAO uses the user's account at the login site. If the patient was selected from some other site, a visitor account is used at that site. All the DAOs associated with any other sites also use visitor accounts. Data requests are delivered to this array to be packaged appropriately and forwarded to the several VistA sites at which the selected patient has been seen. This design will allow the requests to be multi-threaded.

Writing to VistA
MDO currently writes no data to VistA.