Blaise Data Server
The Blaise Database Server available for Blaise Internet is also able to handle I/O request from other Blaise applications and components like the DEP and Manipula. Also all CATI functionality can be handled by this server. By using a Blaise Data Server much better I/O performance in a LAN / WAN environment can be achieved.
The Blaise Data Server has been implemented using two Windows NT services. One service handles the access to the database (the database service) and another service handles CATI management (the CATI service). When the database service is running all access to a Blaise database stored on that server will be handled by the database service. All applications that want to access the Blaise database on such a server will have to address the database service.
All Blaise tools have been made 'database service aware': when the service is running they will address the service and when the service is not running the will do file I/O the same way as in previous versions of Blaise. For use of Blaise services on machines that do not have Blaise fully installed a minimal requirement is the Microsoft XML Core Services Library (MsXML4.DLL).
Note that existing applications that have been developed using previous versions of Blaise do not require any changes. When those applications use the Blaise tools shipped with this release they will start using the Blaise Data Service. The behaviour of those applications remains the same. However there are some exceptions.
- When the Data Service is running the access mode of Blaise Applications is ignored: access to Blaise data files can not be blocked by other Blaise (4.8) Applications.
- When the last Blaise (4.8) Application disconnects from a Blaise data file its lock file does not disappear immediately when the Data Service is running.
Accessing Blaise Data files on a Blaise Data Server by other software.
The fundamental principle behind the Blaise Data Service is that all Blaise data files are accessed only by the Blaise Data Server in order to provide good concurrent access for multiple Blaise applications. Therefore it is not a good idea to access shared Blaise data files directly without using Blaise applications.
If you want to access Blaise data on a Data Server by non-Blaise software we recommend the following: Make a private copy of the Blaise Data files and operate on that copy. Notice that you should only do this for read-only operations; modifying Blaise data should only be done through Blaise applications.
There are two ways to create a copy of a Blaise Data file:
- Manually in the Control Center: use the Copy action of Data File Management.
- Programmatically by the Blaise API Component: use the CopyFile method of the DatabaseManager object.
When using the Blaise Data Server it is not advised to mix the use of Blaise 4.7 or earlier with Blaise 4.8.
Accessing a Blaise database on a Blaise Data Server using 4.7 is still possible, but access will fail when the database is also being used by the database service. When a 4.7 tool has access to a Blaise database, accessing that database using the data service will fail.