Certification Summary

The models created during conceptual application design are similar to models created during conceptual database design. Conceptual application design turns requirements identified during the business requirements phase into abstract processes and data flows. The processes of a conceptual design can be drawn using a procedure diagram. The procedure diagram is similar to a workflow diagram or a flowchart in that it attempts to capture the steps of a particular system task. You will often need many procedure diagrams in order to document all of the tasks in a business requirements document.

Data flow diagrams (DFDs) document the information or data that passes from process to process. It also captures the interaction of the system with external entities (like humans or other computer systems) and data stores. A DFD concentrates on understanding the inputs and outputs of a system—how procedures are able to get the information they need to perform their tasks and where that information flows from there.

There are several possible architectures for which an application can be designed. A single-tier (standalone) application is designed to run on its own and does not have any related outside components. A two-tier application does have one external component, although that is usually just a database running on a server. Sometimes two-tier applications have server components that are designed to handle some of the processing from the client. An n-tier application is designed to run across several servers in a distributed manner. Because n-tier applications require special server software such as Microsoft Transaction Server (MTS, for Windows NT) or Component Services (for Windows 2000) in order to communicate with one another effectively, they are the most complex to develop.

Two-Minute Drill

Creating a Conceptual Model of Business Requirements

• Conceptual design is the process of identifying the components of the system and establishing their relationships with each other.

• Procedure diagrams are used to document the tasks of a system as a series of steps.

• Data flow diagrams (DFDs) document the flow of data through the system.

• Two popular DFD notations are Yourdon & Coad and Gane-Sarson.

Defining the Technical Architecture of a Solution

• Technical architecture is the overall structure of an application.

• Single-tier architecture is for applications designed to run on a single computer without connectivity to other systems or applications.

• Two-tier architecture, traditionally called client/server architecture, is for applications that have both client and server components.

• Three-tier and n-tier architectures distribute a single application over three or more computers.

Validating Conceptual Design

• Conceptual design is validated by mapping all the procedure and data flow design diagrams to the identified business requirements.

• Each business requirement must have one or more procedure diagrams, ensuring that each business requirement is covered in the design.

• The only business requirements that do not need procedure diagrams are nonfunctional requirements.

Self Test

The following questions will help you measure your understanding of the material presented in this chapter. Read all the choices carefully because there might be more than one correct answer. Choose all correct answers for each question.

Creating a Conceptual Model of Business Requirements

1.	Which diagram notation is used to break a process down into a series of steps? Data flow diagrams (DFDs) Procedure diagrams Yourdon & Coad notation Process step notation
2.	Which diagram notation is used to display how packets of information are passed between processes and other system entities? (Choose all that apply.) Data flow diagrams (DFDs) Procedure diagrams Yourdon & Coad or Gane-Sarson User interface site map
3.	What is the aim of the conceptual application design phase? (Choose all that apply.) To translate business requirements into application design To design a system that meets the basic needs of the user To develop a conceptual database design To provide input to the logical design phase
4.	What does a circle represent in a Yourdon & Coad data flow diagram? Data store External entity Process Data flow between processes
5.	What is the purpose of conceptual user interface design? (Choose all that apply.) To develop draft versions of every screen in the application To plan and design the application based on the user requirements To document how packets of information flow through the application To construct profiles of the potential users and understand their general characteristics
6.	What types of characteristics about the target users of an application are documented inside a user profile as it relates to conceptual application design? (Choose all that apply.) User names, passwords, and job titles Level of computer skills Most frequently used areas of the application Geographical location

Answers

1.	B. A procedure diagram breaks a complex system process down into a series of smaller steps. Procedure diagrams can contain a high or low level of detail. x A is incorrect because DFDs display how packets of information are passed between system entities. C is incorrect because Yourdon & Coad is a notation for DFDs. D is incorrect because there is no such thing as process step notation.
2.	A and C. A DFD is used to display how packets of information are passed between processes and other system entities. Yourdon & Coad and Gane-Sarson are two of the most popular DFD notations. x B is incorrect because procedure diagrams deal only with processes and not the information passed between them. D is incorrect because a site map defines process flow between screens.
3.	A, B, C, and D. All answers are correct. A conceptual design translates the business requirements identified earlier in the design phase into an application design. This design focuses on the needs of the user and does not take many system or nonuser needs into consideration. Conceptual database design is part of overall conceptual design, and the results of conceptual design are fed into the phase that follows—logical design. x There are no incorrect answers.
4.	C. A circle represents a process in the Yourdon & Coad DFD notation. x A is incorrect because a data store is represented by two parallel lines. B is incorrect because an external entity is a rectangle. D is incorrect because data flow is drawn using a line with an arrow.
5.	B and D. Conceptual user interface design is the process of understanding who the users are (by constructing user profiles) and conceptualizing the application from their point of view. x A is incorrect because only a couple of screens are mocked up during this stage. C is incorrect because data flow diagrams are responsible for documenting the flow of packets of information.
6.	B, C, and D. The user profile is used to come up with a general understanding of your users’ special characteristics so that the application can be tailored to their needs. Understanding their level of computer skills is important to designing a user-friendly yet efficient application. Understanding the areas of the system they will use most frequently is important so that those areas can be streamlined. Finally, understanding general geographical locations will help determine what network, server, and other technical resources will be required. x A is incorrect because user names and passwords are not important to understanding the characteristics of your users.

Defining the Technical Architecture of a Solution

7.	Which application architecture would most likely be used for a productivity tool, such as a simple calculator? Single-tier Two-tier Three-tier or n-tier XML web service
8.	XYZ Corporation has a custom-designed VB .NET application that involves 11 different computers in its small corporate office. Ten of those computers are client workstations, as each employee has his or her own copy of the application. The application also requires a database server for data storage, although the application itself is not installed on that machine. What type of architecture is this application an excellent example of? Single-tier Two-tier Three-tier or n-tier Eleven-tier
9.	XYZ Corporation is developing a complex, online ordering system for its global web site. The application must be available 24 hours per day, 7 days per week. The application designer has decided to create a distributed VB .NET application, converting .NET assemblies into COM components. These components will be running on a small cluster of Windows 2000 machines. Which Microsoft technology will enable these components to participate in transactions and object pooling? Microsoft Transaction Server (MTS) Microsoft .NET Framework and Common Language Runtime (CLR) Microsoft Solutions Framework (MSF) Component Services
10.	Which of the following are advantages of using an n-tier architecture when compared with one- and two-tier architectures? (Choose all that apply.) Performance is better for applications with hundreds of thousands of transactions per day. Performance is better for applications with a few dozen transactions per day. The application can be scaled more easily as transaction growth requires. The application is cheaper to set up and maintain in the long run.
11.	Which of the following are typically features of a web service application? (Choose all that apply.) It cannot be used directly by users. Its programming language and operating system can be different from the applications that use it. A web browser is required to use it. It has to be exposed to the Internet.
12.	Which of the following are disadvantages of using an XML data storage solution? (Choose all that apply.) Data is more difficult to search and sort. All of the XML code has to be parsed in order to read one column of data. XML code can be read equally well across many operating systems and platforms. XML is self-describing.

Answers

7.	A. A simple calculator most likely would be developed as a standalone, single-tier application. This is because a calculator probably would not need access to network resources such as databases and application components deployed across multiple servers. x B and C are incorrect because a calculator does not need a server component. D is incorrect because a desktop calculator probably would not be deployed as a web service.
8.	B. No matter how many independent client workstations are involved, the labeling of tiers usually involves counting one client plus the number of server computers that client relies on (including server computers relied on by other servers). In this case, because there is one client and one database server, this is a two-tier application. x A is incorrect because a single-tier application does not rely on a network or on access to database servers. C is incorrect because this application does not have server-side components installed on multiple servers. D is incorrect because the number of client workstations does not affect the number of tiers.
9.	D. Component Services is the name of the Microsoft server software that provides transaction and object pooling services in a Windows 2000 environment. x A is incorrect because MTS only runs in a Windows NT environment. B is incorrect because .NET does not have native transaction services and relies on COM+. C is incorrect because MSF is an application design methodology and not a piece of server software.
10.	A and C. Among several others, two of the advantages of an n-tier architecture are its ability to handle more transactions in a certain period than one- or two-tier architectures possibly can and its ability to be scaled more easily due to the fact that servers often can be added to a solution without coding changes. x B is incorrect because n-tier applications have more processing overhead than single- and two-tier architectures. D is incorrect because n-tier architectures are more difficult and complex to set up and maintain and thus more expensive in the long run.
11.	A and B. The users of web services are always other applications, and not users directly. Since web services are based on a set of common standards, the programming language and operating system of the client and the server are independent of each other. x C is incorrect because any type of application, such as Windows desktop or mobile phone applications, can use web services. D is incorrect because web services can be used on private networks such as an intranet, without being exposed to the security concerns of the Internet.
12.	A and B. The nature of XML makes it more difficult to sort and search. Because the entire XML document has to be parsed in order to extract aggregate data, filtered data, and the data from an entire column, it is many times slower than a relational database solution. x C is incorrect because the cross-platform nature of XML is a definite advantage of the format. D is incorrect because XML data has embedded element and attribute names that serve to describe the data fairly well. Also, XML can point to a schema or DTD, which further describes the data.

Validating Conceptual Design

13.	What is the best technique for validating conceptual user interface design? Comparing the ORM model with business and user requirements Usability testing Comparing procedure and data flow diagrams with business requirements Generating draft logical design documents
14.	What is the best technique for validating conceptual application design? Comparing conceptual design diagrams with business and user requirements to ensure that everything is covered Creating cross-reference matrices Usability testing Comparing conceptual design diagrams with logical design diagrams to ensure that everything is covered
15.	What is the most likely consequence of not validating the conceptual user interface design? The application performance is slow or degraded. Users have a difficult time accessing the features and functions they use most often. There will be a significant difference between the conceptual database design and the conceptual application design. An application that deserves to be spread over three tiers might mistakenly be developed as a two-tier application.

Answers

13.	B. Conceptual user interface design is usually validated by some form of usability testing. Two or three sample screens are created and presented to users to solicit their feedback before a user interface design is decided on. x A is incorrect because the ORM model deals with database design and not user interface design. C is incorrect because procedure and DFD diagrams deal with application component design. D is incorrect because logical design documents are not generated until conceptual design is complete.
14.	A. Comparing the procedure and DFD diagrams with the business and user requirements is the best way to validate a design. Each business requirement should have one or more conceptual diagrams to ensure that everything is covered. x B is incorrect because cross-reference matrices do only a partial job of validating the design. C is incorrect because usability testing is used to validate user interface design. D is incorrect because location design diagrams are not generated until after conceptual design is complete.
15.	B. User interfaces that have been designed without usability testing often have unintended confusing elements. Terminology that is frequently used in the software development world may be unfamiliar to the average user, and frequently used features may be hidden in hard-to-access menus. x A is incorrect because while application performance may be slower, it is not a primary consequence of skipping this step. C is incorrect because user interface design is not often affected by the differences between database and conceptual application designs. D is incorrect because a poor user interface design will not affect application architecture decisions.

Lab Question

1.

Arrange the following software design tasks in proper chronological order from earliest to latest.

1. Transforming data and business requirements into a conceptual design

2. Developing business requirements

3. Visualizing the design

4. Developing an application prototype

5. Developing functional specifications

6. Developing a database schema

Answers

1.

The correct order of software design tasks is as follows:

C. Visualizing the design

B. Developing business requirements

E. Developing functional specifications

A. Transforming data and business requirements into a conceptual design

F. Developing a database schema

D. Developing an application prototype