DAT602 Database Application Development Lecture 12 C/S Model Database Application.

DAT602 Database Application Development

Lecture 12 C/S Model Database Application

• In this lecture, you will see how to create a simple Client / Server model database application.

• We will build a simple library book management system for demonstration.

Database Application Development - Lecture 12

• There are basically two major kinds of modern architectures: two-tier client/server and three-tier—also commonly called n-tier.


• Two-tier client/serverA two-tier application ideally provides multiple workstations with a uniform presentation layer that communicates with a centralized data storage layer. The presentation layer is generally the client, and the data storage layer is the server.


Two-tier client/server• Following diagram shows how two-tier

systems give clients access to centralized data.


• Two-tier limitations- Fat clientsTwo-tier, fat-client systems are notorious for their inability to adapt to changing environments and scale with growing user and data volume. Even though a client's primary task is the presentation of data, a fat client is loaded with knowledge completely unrelated to that task.


• Two-tier limitations- Object reuseIn one common sense, object reuse is simply code reuse.In two-tier model, code is too close to database server, it is not easy to be modified when business logic changes. Two-tier model lacks flexibility.


• When to use a two-tier design?If you can answer "yes" to each of the questions in the checklist, then a two-tier architecture is likely your best solution.- Does your application emphasize time-to-market over architecture?- Does your application use a single database?- Is your database engine located on a single host?- Is your database likely to stay approximately the same size over time?- Is your user base likely to stay approximately the same size over time?- Are your requirements fixed with little or no possibility of change?- Do you expect minimal maintenance after you deliver the application?


• Three-tier’s advantage- Isolated database connectivityThree-tier model helps you to split presentation layer and data storage layer. Changes of these two layers won’t affect each other.


• Three-tier’s advantage- Centralized business processingThese centralized rules for processing data inside business objects are called business rules . No matter what your problem domain is, the rules for how data should be processed rarely change.


• Three-tier’s advantage- Business object presentationThe presentation layer of a three-tier application should therefore contain only user interface code that can be modified easily on a whim.The presentation layer of a bank application:• The teller window's console at the bank• The ATM machine• The web applet


• Drawbacks to the three-tier architectureChief among its drawbacks is the level of complexity it adds to a system.It is also harder to find software engineers who are competent in three-tier programming skills such as transaction management and security.


• In next, I’ll give you a demonstration for how to create a simple two-tie client server database application.

• This C/S database application is developed for library management.


Step 1: write your specification of this library application.What kind of users be involved in this application?What features this application should has?Simple hierarchy of your application.


Extremely Simple Specification• In this application, there are two kinds of users:

librarian and normal user.• Librarians has fully authorization, they can add, modify

or remove books, users information, and also can add or modify loan log.

• Normal users can observe their loan log and check their accounts’ status.

• This application should consists with two client GUIs, one for librarians, and another for normal users.



Step: 2 Design and build database of this library application.

Diagram: Structure of library application

• Step 3: implement basic operation: insert record, remove record, query for each table.

• Step 4: Design GUI











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DAT602 Database Application Development Lecture 12 C/S Model Database Application.

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