TS5352 – Enterprise Database Systems
Unit 6 Discussion 1
August 16, 2009
As the current information system of MVCH becomes outdated and in need of
improvements as is the case with the current system used for patient accounting,
administrative services, and financial management, the consulting firm CSCI has begun
to inquire about a system where integration of services across business units will now
meet the needs of a growing and changing MVCH and local community.
To do this CSCI is in the process of helping MVCH set up an n-tier client/server
architecture. By doing this, integration of business processes that serve the various
departments of MVCH, will now use a system that is set up for the hospital as a whole
and not just individual departments. Data can now be reliable and secure and serve the
hospital and community needs, not just departmental needs within departments. The
changing and dynamic environment at MVCH means the database structure must meet
At present, MVCH has “limited integration” with its information system. MVCH’s
present system is a relational two tier system that still is paper based in some areas, and is
departmentalized in other areas. A relational two tier system is a system where the
database storage logic is located on a server and the processing and presentation logic is
located on the client machine, in the case of a fat client. With a thin client, the storage
and processing logic are located on the server and the presentation logic remains on the
client. Finally the distributed environment is where the server and client share the
In either case a two tier system, presently in place at MVCH, uses just the one server,
plus the client, for all logical layers; data, processing, and presentation, making it difficult
to work with one layer without involving the other layers. The load on a particular client
as a result is heavy with the added deficiency of having to install the DBMS on all clients
that use the data on the database server.
File servers tend to fit into this category. The database server and the client are
responsible for all the work that the program must perform. A step above the mainframe,
file servers and the subsequent two tier and n-tier architectures differ in that a mainframe
is a centralized approach whereas the client/server approach decentralizes the
applications execution, splitting the responsibility of the data, processing, and
presentation logics amongst different servers.
The logic behind an n-tier system is that the presentation layer, storage or data layer, and
the processing layer become separate. This means ease of use, ease of creating the layers,
more flexibility, and increased manageability. For instance a programmer writing the
presentation logic for a user interface need not concern himself with the data logic layer
or the business logic layer that handles data storage and business logic respectively.
Within MVCH the upgrade to an n-tier system in which a database server handles the
data storage, an application and web server handles the processing logic, and the client
handles the presentation logic, in this case a four tier system, means that MVCH’s data
and use of the data will be scaleable, not redundant, secure, accurate, and maintainable,
unlike the present system where data is duplicated in some areas of processing and paper
based in others.
An n-tier system, as mentioned above, separates the data logic, business logic and
presentation logic with “n” amount of servers that host the respective layers and their
responsibilities. For MVCH the move from a two tier, non-separate layer system to a
separate layer system or n-tier system means separate responsibilities for the respective
At MVCH the proposed system by CSCI involves the client handling the presentation
logic where the user interface is created. The presentation layer for MVCH must be easy
to read, easy to navigate, easy to understand, and visually appealing as the doctors,
patients, and administrators use the system to meet the needs of the hospital and
The business layer in MVCH’s new system will reside on a web server and application
server where the processing of the application’s logic will be shared. This layer will
comprise the bulk of the system’s work, providing to MVCH’s concerned individuals
(doctors, patients, and administrators) the services that they need. A web server might
host the website or interface to the systems services whereas the application server might
host the application that processes the services as required by the user.
The database server will handle the storage and manipulation of data with the help of the
RDMS that is set up. The need for data warehousing within MVCH future needs is also
set up here in the data logic layer, at least the database and data used in its queries.
We have seen in recent years this move from a mainframe, centralized approach, where
all of an application’s logic layers are handled by limited resources, the mainframe, to
systems that use two and n-tier configurations where separation of data, processing, and
presentation makes for a well tuned, scalable, interoperable environment.
Hoffer J. Prescott M. Topi H. (2009). “Modern Database Management.” Chapter 9, 14.