Develop Your Own Database Software HTML version
with a SQL Server, running on the same system. The client application’s connection is authenticated
by the LAN and SQL server with a user-supplied or application-generated login ID and password. In
some cases, Microsoft Windows provides a degree of connection security management. That is, using
domain-managed security, client applications need not provide additional user names and passwords
to SQL Server—once they are authenticated by windows. The client must also deal with connection
problems caused by trouble on the server, on the network, in the application itself.
Data Capture: The client presents forms for the user to fill in with data. The client validates data
values before they are sent to the database. This pre-validation often involves cross-checking form
fields against other fields, either on the form or in the database. Validation can take place as fields
are filled in or completed, or as the form is committed. These validation criteria are often referred to
as client-side business rules.
Data retrieval: The client submits queries to the database engine for processing and retrieves the
result sets, as required. Another responsibility of the client is to manage data returned to the
Data Presentation: The client application is responsible for displaying results from queries, as
needed. This task might involve filling a Grid or Listbox control.
Error Management: The client is also responsible for trapping and dealing with the errors. Effective
and comprehensive error management is the sign of a successful client application.
The Server’s responsibilities
In any client/server implementation, the server is not just a data dumping ground. The server is also
responsible for intelligent resource management, security management, data management, query
management and database system management.
Resource management: The server is responsible for managing its own resources. These resources
include RAM, connections, disk space, CPU time, threads, and a set of caches or queues. If the server
has to compete for resources with other Windows 2003/ NT services, its job is made that much
harder. For example, if the server must also act as a print server or domain controller, the SQL
Server operations will become slow.
Security management: The server prevents unauthorized access to itself and the database while
permitting guarded access to those with valid permission.
Data management: The server is also responsible for the validity and integrity of the data sent to
the database system from the client application.
Query management: The server processes SQL queries from the clients, which involves syntax and
object checks and compilation of a query into a valid and efficient processing plan.
Database system management: In managing the database system, the server manages all
connections to the database. The server also maintains tables, indexes, procedures, rules, triggers,
data types, list of valid users, and other database objects.
Let us list and discuss the important topics we should be familiar with concerning the windows
operating system. Here my focus will be on discussing topics, which are more relevant and useful for
a programmer who is into application software development.