Databases Reference
In-Depth Information
• greater user satisfaction with the newly installed distributed applica-
tion than with the previous non-distributed application
• lower costs for resources and better efficiency in the processing of
data with the distributed applications
• improved maintenance of the Distributed Database System and the
distributed data administration procedures
FUTURE ISSUES
The development of such a project from conception to operation
requires a long time span. Some large-scale distributed environments and
applications could take more than two years to complete. During the two-
year development period, however, distributed database technology and
the organization's requirements are likely to be changing. This situation
does, of course, present the possibility of having an obsolete system on
completion. A few observations follow:
• The technology of the truly distributed, all-powerful, all-embracing
data model and language to provide transparent accesses to separate
databases and computers is still not as mature as might be expected.
All the present distributed environments in support of operational dis-
tributed database applications are either homogeneous or federated
with translation mechanisms.
• Issues of access control, concurrence control, schema and transaction
management, performance, capacity growth, and support for complex
environments are still in the research stage. In practice, distributed
data processing is still partly a learning process.
• In current practice, users depend increasingly on single vendors to
supply the DBMS and communications products. Some very difficult
decisions must be made by system designers to achieve the best bal-
ance of functional ability, performance, and vendor independence. The
use of standard products alleviates the vendor dependence problem.
• In the near term, the release of an RDA/SQL standard will provide tech-
nical specifications on how to package SQL network service requests.
These packages contain service elements for association control, which
includes establishing an association between the client and server re-
mote sites and managing connections to specific databases at the serv-
er site; the transfer of database operations and parameters from client
to server, and the transfer of resulting data from server to client; and
band transaction management, which includes capabilities for both
one-phase and two-phase commit. The introduction of the RDA/SQL
standard will pave the way for wider interoperability among heteroge-
neous distributed DBMS nodes supporting SQL data languages.
• The migration from a centralized environment to a distributed environ-
ment requires careful planning. A more important consideration is that
data sharing and resource consolidation requires cultural changes.
Search WWH ::
Custom Search