Chapter 12-13 - Assessment
Database Management - Assignment 6
Pretty good answers, but a little brief in some places. Take a bit more time to explore
the concepts in your answers.
Grade: 9.8 out of 10 points
Questions
1. What is Client/Server computing, and what benefits can be expected from Client/Server
systems?
Client/Server computing is a computing model for distribution of functions between
clients and servers. They can reside in the same computer or different computers.
Computers residing clients and servers are connected using network system. Clients
request services from servers and servers provides requested services for clients. One
client can request services from different servers as well as servers can provide services to
many clients.
For example, suppose that in the ACCENT centralized library system that has been used by
all schools’ libraries in Los Angeles Unified School District, the data server resides at the
LAUSD IT department. All schools are its clients. Schools request services from the server.
The transaction processor retrieves required information from the data server and returns the
required services to the schools.
Server
Database
TP
Sends
requests
School 1
Returns
Requested
data
School 2
School 3
School N
Some of the benefits of Client/Server system are:1. It is practical and cost-effective in general.
It reduces costs in developing, implementing and operating because client users
use PC based systems and all technology updates and changes reside at the server side
only.
2. It becomes a common system for the highly competitive global market.
Because of the distributed computing, the availability of enterprise-wide data
access and the portability, it increases the end user productivity and it is useful for business
of all sizes.
3. It provides additional benefits to the MIS personnel.
Because the application systems and databases reside in the server, all
programmers’ transactions go to the server. It reduces the development time and increases
the programmers productivity.
2. Describe and explain the Client/Server architectural principles.
Client/Server architecture is a system that is formed by clients, servers and
communications middleware interacting each other. To interact properly, the components
are required to meet some basic principles. They are stated below.
-
Independence of hardware and software
As mentioned in question one, clients and servers have relations of one to one,
many to many and one to many. When there are many to many relationships between
clients and servers, clients may run under different operating systems, different networking
systems, different application systems and servers may be products from different vendors
as well. To interact under this situation, all components should be free of hardware and
software differences.
-
Open access to services
All services must be independent of the location of client and servers, and also the
server must respond to every on demand services from clients.
-
Distributed processing
Distributed processing among clients and servers is the main characteristic of
client/server systems. Distributed processing includes the clear definition of functions
between client and server processes, sharing server processes among all client processes to
utilize all resources and finally, the easy upgradeability of server processes to run on more
powerful platforms.
-
Standard use of principles within the architecture
The standard use of user interface, data access, network protocols and others
within the client/server architecture encourages all components to interact well and increase
performance.
3. Suppose you are currently considering the purchase of a Client/Server DBMS. What
characteristics should you look for? Why?
If I purchase a Client/Server DBMS, I would look for a DBMS that provides a
transparent data access to several database servers. It means the DBMS is free from
network dependency and database server dependency.
Because of these characteristics, clients request data from several servers without
regard to the physical location of the server on the network. In addition, the server selects
the records matched and provides them through multiple network protocols to clients. This is
why these characteristics are important to enhance the end user performance.
4. Name and describe three server components.
In the client/server environment, clients request services from the server regarding
data retrieval, printing, faxing and other transactions. This is why a server is a combination
of powerful hardware and software components to handle users’ requests.
Three important server components are a large hard disk, the server operating
system and a multiprocessor.
1. A large hard drive is required to store clients’ data throughout the network. It is shared
among several clients and every client can access as if it were a local hard drive. In
addition, it is used to store all print jobs temporarily until the client finishes sending the print
job.
2. A server operating system is a main component for the server because it hosts server
applications, enables client-server-network communication and it is a gateway to the internet.
3. A server needs a powerful CPU to handle multi tasking for distributed processing because
multiple processing is an important function in a client/server environment.
5. Name and describe the three database middleware components.
The three database middle ware components are Application programming
interface (API), Database translator and Network translator.
1. The application programming interface (API) is intermediary software that allows generic
SQL code and transfers the SQL requests to the database translator. Because of the help of
API, the client process is independent of the database server and the server is independent
from the client applications as well.
2. The database translator translates the generic SQL requests into the specific code for
each database server. It also manages the communication between two database servers if
the request needs the data from two different servers.
3. The Network translator manages the network protocols. It also controls the network
communications of each database.
Below is the illustration of middleware components in a client/server environment.
SQL
API
Client
Requests
Database
Translator
Network
Translator
Network Protocols
Sends SQL
Database
Server
Requests
Database
Server
6. Why are standards important?
Standards are important because they provide a clear and orderly way for systems
to communicate, regardless if they are between computers or human beings.
For a client / server environment, standards provide protocols so clients and
servers can communicate effectively and without error.
There should be more discussion here. Give an example or illustrate somehow the
pitfalls of failing to have and follow standards.
7. Describe an existing Client/Server computer system used by a library. If you don't know of
specific example, describe a Client/Server system that you think would be useful to a library.
In my school library, we are using the ACCENT library management system. It is
sponsored and installed by the LAUSD IT department. LAUSD is using the Client/Server
library management system for its cost effectiveness to the schools.
In this situation, computers at all school sites in the Los Angeles district sharing the
client/server system are the clients of the system. The Accent system is the client
application system that accesses the database server. All schools processes run under
different operating systems such as Windows 98, windows 2000 and Macintosh OS. At the
server side, the database server runs under the Unix server operating system and Oracle
database. The data and the database engine reside on the database server computer. The
client sends SQL requests to the server through TCP/IP network. The server receives the
SQL code, validates it, processes it and sends results back to the client.
For example, when a student checks out a book, the client application sends the
required student ID number to the server and the server retrieves the required record and
returns it to the client side. After finishing the transaction, the client application requests the
server to update the student record. At the same time, other several clients are sending
requests to the server.
This is why, the library system with hardware independence, software
independence, open accessibility to all services and distributed processing among clients
and server is critical for the Client/Server computer system. In other words, this system
provides transparent data access to multiple and heterogeneous clients, regardless of the
hardware, software or network platform used by clients.
Using the ACCENT Client/Server system within the district schools is beneficial to
users, programmer and employer. It is practical and efficient in resource utilization and it is
therefore cost-effective. It reduces development costs, implementation costs and operational
costs. In addition, it reduces development time and increases programmer and end-user
productivity.
8. Explain how the main components of a DSS interact to form a system.
A decision support system is an organization of computerized tools that enables
business decision makers (managers) to analyze and understand the business problems and
to make managerial decisions. These computerized tools: the data extraction and data
filtering component, the data store component, the end user query tool and the end user
presentation tool are the main components of a DSS interaction to form a system.
1. The data extraction and data filtering component
This component takes the data from the operational database and the external
data sources to select the relevant records for the DSS data store component. For example,
to determine the recommended new book lists, the library system needs new titles from
vendors.
2. The data store component
This component is a DSS database. It contains business data and business model
data. The business data are the snapshot representation of the business situation. They are
the summary of the data from the operational database and from external data sources in
order to support data analysis and to increase the query speed.
3. The end user query tool
This is useful for the data analyst or decision maker to create the queries and
advises the user what data to select and how to build a suitable business data model for a
successful business.
4. The end user presentation tool
This component is important to organize and present the data for managerial
decisions. The user is allowed to select the appropriate presentation format for the required
information and the tool prepares the presentation.
For example, in a DSS for the library management area, daily transaction records,
students’ records are the operational data. External data will be lists of new books from
vendors together with the reading levels and the LAUSD recommended book lists.
Business data from the data store shows summary of transaction data such as how many
books checked out, how many books over due in a specific time limit, a summary of checked
out by genre and by reading level. End user query tool advices the user on which books to
order more, suggests recommended new books for current patrons’ reading levels and
provides current library usage by grades and overdue status. The librarian uses the end
user presentation tool to organize and present the data by means of summary reports, pie
and bar graphs for making decisions on books orders, preparing curriculums and setting up
library policies.
9. While working as a database analyst for the Library of Congress, you are asked to be part
of its data warehouse project team. Prepare a high-level summary of the main requirements
to evaluate DBMS products for data warehousing.
Because the operational data and the decision support data are different in many
ways, there are many requirements for a DBMS to support DSS. Although the operational
data needs low summarized and highly normalized data, the data for data warehousing
requires high summarized and non-normalized one. In addition, the operational data needs
simple query scope and complexity, however, the decision support needs high query activity
in very complex forms and a large data volume. This is why, the database schema, data
extraction and loading, the end-user analytical interface, and the large database size are the
main requirements for a DBMS to qualify for data warehousing.
1.
Database Schema
The database schema should be designed to handle complex data representations
and to support multidimensional queries because the data for data warehousing are
aggregated, summarized and related to many other data elements. In other words, the
DBMS must support features to handle non-normalized and complex structures such as
bitmap indexes and data partitioning to increase query speed.
2.
Data extraction and filtering
The data store in data warehousing is extracted from the data from the external
sources and the data from the operational data. This is why the DBMS must support
advanced data extraction and filtering such as batch and scheduled data extraction,
hierarchical and relational data extraction and checking for inconsistent data. Moreover,
data integration, aggregation and classification are critical to the data warehousing.
3.
End-user analytical interface
This is one of the most critical decision support DBMS requirements. This permits
the user to analyze the data and to define business problems easily. Finally, the user can
generate the necessary queries and navigate through the data to simplify and accelerate the
decision making process.
4.
Database size requirements
Because the DSS DBMS contains duplicated data and non-normalized data to
improve data retrieval and to support multidimensional quires, the data store tends to be very
large. Therefore, the DBMS must support very large databases.
10. Suppose you are selling the data warehouse idea to your users. How would you explain
to them what multidimensional data analysis is and what its advantages are?
Multidimensional data analysis is the processing of data such that data are viewed
as part of a multidimensional structure. In other words, it is the processing of operational
data that are related to other factors. Because data extracting, integrating, aggregating and
presentation are important in DSS to get the ad-hoc queries, multidimensional data analysis
is critical for data warehousing.
Its advantages are:1. This analysis produces advanced data presentation tools that are available to
present multidimensional data in 3-D graphs, crosstabs, cubes and so on.
2. It provides multiple data aggregation levels in order to create drill down and roll up
across time dimensions quires.
3. This analysis is useful to handle business-oriented variables, financial and
accounting ratios and statistical and forecasting functions and so on.
4. It supports advanced data modeling such as variable assessment, variable
contributions, linear programming and other modeling tools.