1

A Client-Server Data Application

For

Production Drawing Department

High Steel Structures Inc.

Spring 2010

Than Lwin Aung

Department of Physics and Engineering

Elizabethtown College

Elizabethtown, Pennsylvania

Email: aungt@etown.edu.

This project report is presented to the Faculty of Physics and Engineering Department, Elizabethtown

College, in partial fulfillment of the Requirements for the Degree Bachelor of Science in Computer

Engineering.

Abstract: As the information processing is an integral part of business organizations,

developing an efficient information system has become a primary concern for software

developers and software engineers. Mainly due to the complexity associated with the software

development, many organizations, such as CCTA (Central Computer and Telecommunication

Agency), ISO (International Standard Organization) and SEI (Software Engineering Institute)

have implemented and standardized different software development models, such as Water Fall

Model, V Model, RAD (Rapid Application Development), Agile Programming, XP (Extreme

Programming), and ISO 12207 etc. Although the primary goal of these models is to deliver the

software product, which meets the user requirements within the time and budget constraints,

they provide different development environments. While the water-fall model provides a more

structured approach of developing software systems, RAD is more suitable for systems which

are dynamic in nature. My goal for the senior project is to develop a client-server data

application system, which will facilitate the part of information systems used in the Production

Drawing Department of High Steel Structures Inc. This paper is to demonstrate the software

development process of my senior project, and the evaluation of the project outcomes.

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1. Introduction

High Steel Structures Inc. is a company which not only deigns bridge structures but also

fabricates, ships, and erects them to the sites. Although for the company as a whole, there are

various business activities and their related information systems, my senior project will be

confined to the business activities related to the Production Drawing Department. As its name

suggests, the production department is concerned with the production of engineering and design

drawings for bridge structures, and the information systems used in the department are primarily

concerned with keeping track of information related to design drawings, and time and costs

associated with engineering drawings and other information related to shop drawing, estimate

drawing etc. Although there are more than 10 sub systems, the primary systems currently in use

are DCS (Document Control System), Estimate Drawing System, Shop Drawings System. Since

each information system was developed to satisfy the specific needs of the particular business

activities, there are very few interactions among those separate information systems. In addition,

most of those systems were developed more than 10 years ago, and some of the processes have

become obsolete and cannot meet the requirements for the new business activities. Those

problems and the requirements for new business changes entail the current systems to be

modified and updated.

As of now, the company cannot provide a solution to integrate those separate information

systems and their related databases, so they would like to update the existing systems in a piece-

meal approach. Actually, my last summer internship was primarily responsible for the

incremental update of those separate information systems to meet the requirements of new

business processes. However, the piece-meal approach is not an ultimate solution to the

information systems, as it cannot provide the structured approach of integrating all the

information systems.

Therefore, as a senior project, I developed a prototype of integrated information system,

which can support the functionalities of different sub information systems. The new integrated

information system will not only eliminate data duplication but also provide new information

processing features to meet the requirement of the new business activities. Moreover, it can

provide data integrity and security as it will centralize all important data on the central database,

instead of storing on the different databases.

During the summer, I analyzed the current information systems and defined the problems

and requirements for new updates. Throughout the analysis phase of the project, I used both the

structured and object-oriented approach to model the current business activities and their related

information systems. The details of the techniques and software development processes will be

further discussed in the following sections. During the fall semester, I designed and implemented

the prototype of the client-server information system to meet the requirements specified in the

summer. In the following spring semester, the working prototype was tested and evaluated to

examine whether it actually can be implemented for the real information system.

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2. Background

2.1 Software Development

Software development processes are the activities which take place during the

development of a software product. Primarily, there are 4 major software development activities

or phases:

1. Requirements Analysis and Specification

2. Design

3. Implementation

4. Testing & Evaluation

Various Software development models specify how we go through software development

processes depending on the nature of the software being development. The primary goal of these

models is to allow us to deliver the software on time and budget with all the functions specified.

According to SEI (Software Engineering Institute) at CMU [1]:

“Organizations and governments worldwide will spend about $1 trillion this year on IT projects.

Recent data suggested only about 35 percent of those projects are likely to be completed on time

and on budget, with all their originally specified features and functions. Many projects, perhaps

20 percent, will be abandoned, often after multimillion-dollar investments—and the biggest

projects will fail most often.”

This strongly suggests that software development requires that each and every phase of the

software development be carefully carried out.

Depending on the model of software development [2], the transition from one phase to

another can be either iterative or sequential. In the conventional water-fall model, one proceeds

from one stage to another in a sequential manner. However, in the real world, organizations are

subject to change, and it is essential for software developers to cope with new changes during the

software development. Therefore, the modified version of water-fall model, which allows

moving back and forth between stages, has been introduced. Although there are other models,

such as the spiral model, which can provide more adaptation to changes during the software

development, for organizations which are more static in nature, water-fall model still seems to be

more preferable, as it can provide a structured approach of software development in a cost-

effective and time-efficient way.

For my software development, I used the water model since the software developed is

static in nature. The first 3 phases of the software development will be more iterative; however,

the later stages will be carried out in a sequential manner.

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Figure 1: Software Development Phases (The Water Fall Model)

2.2 Software Development Methodologies

A software development methodology refers to the framework to structure, plan, and

control the process of developing an information system. A wide variety of such frameworks

have evolved over the years, each with its own recognized strengths and weaknesses. Until

recently, there have been 2 major paradigms of software development methodologies:

1. Structured Methodologies

2. Object Oriented Methodologies

However, new methodologies, such as Agile Programming and Extreme Programming, have

appeared to cope with the more dynamical nature of newly emerging information systems. In this

background research, I primarily focus on Structured Methodologies and Object Oriented

Methodologies, since I use these two principles, whenever appropriate, for my software

development.

SSADM is one of the famous Structured Methodologies, and it was introduced for CCTA

(Central Computer and Telecommunication Agency), UK in 1980 [3]. It is a structured approach

to the analysis and design of the information systems. It effectively follows water fall model and

Requirements Analysis and Specification

Design

Implementation

Testing

Evaluation

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provides 3 primary modeling techniques: logical data modeling (Entity Relationship Diagram),

data flow modeling (Data Flow Diagram), and entity behavior modeling (Entity Life History). In

other words, SSADM provides three dimensional perspectives of an information system: one is

to define the structures of data, another is to define the interconnection of the components of the

system, and the last one is to define the dynamic behavior of the system. In this way, SSADM

produces the logical models (designs) of the information system.

Generally, the techniques of SSAMD are most appropriate to the procedural (structured)

programming languages and the relational databases. One of the reasons why I did research on

SSADM is that the information systems used in HSSI were developed with MS AccessTM

and

VBATM

(Visual Basic for Applications), which is more procedural than object-oriented, I believe

that SSAM will be the perfect tool for analyzing and modeling the systems.

Nowadays, however, almost all programming languages, such as C++, Java, Visual

Basic.Net etc, are more or less object oriented programming languages. In fact, an objected

oriented approach differs somewhat from the so-called structured approach. In object-oriented

environment, each object is defined by both data and functions, and each object communicates

with other objects by passing messages through the pre-defined interfaces. Due to reusability and

data encapsulation for information hiding, OOP has become poplar. Therefore, in order to deal

with modern programming languages, it is necessary to understand the Object Oriented

Methodologies.

UML is just another object oriented modeling methodology, and it was first introduced

by Grady Booch, Ivar Jacobson, and James Rumbaugh as a standard notion for the object

oriented analysis and design [4]. UML also provides a set of graphical modeling techniques for

the object-oriented programming environment. In contrast to SSADM, UML is a more powerful

tool for the contemporary OOP (Object Oriented Programming) languages, such as C++, Java,

and C#. As the implementation of software requires the use of object oriented languages, UML

will be a better tool for modeling and designing the new information system. Particularly, I use

class diagrams to model the application program.

2.3 Software Architectures

Although both SSADM and UML provide the logical models (designs) of the system,

little do they concern with physical design and implementation. Needless to say, however

logically good the design maybe, it is utterly useless if it cannot be defined by physical

implementation.

In fact, various software architectures provide the framework for a software developer to

physically implement the logical model of the information systems. Generally, every information

system involves three main functions: data storage, data processing (application logic) and data

input and output (user interface). Depending on the software architecture, they can be performed

on a server, on a client or divided between server and the client [5] [6] [8].

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2.3.1 Server Based (Mainframe) Processing

In a server-based environment, all of the functions of the information system are carried

out on the central server. The main server, typically a mainframe computer, is connected by

terminals for data input and output. Although this approach is good for powerful data processing,

it might not be a good option for systems which does not need much data processing.

2.3.2 Stand-Alone Computing and Peer to Peer Processing

In this environment, the data processing is carried out on a stand-alone computer. The

data communication can be achieved through local area network or peer-to-peer network.

However, since the data processing a stand-alone computer can handle is limited, it is not

suitable for heavy data processing.

2.3.3 Client-Server Processing

As we can see, this environment is the hybrid of stand-alone processing and server-based

processing. Although there is a server which handles most data processing, the clients also

perform part of data processing. So, both the server and client share the responsibility of

processing the data. Since this approach optimizes the processing work-load and provides

flexible design, it has become more and more popular. Recently, instead of just two-tier client-

server, n-tier client/server architecture has appeared, in which there are a number of servers

which are responsible for different data process and data storage.

The following table shows the distribution of data, application logic and user interface in

different architecture environments [6].

Architecture Data Application Logic User Interface

Mainframe Server x x x

Client

Stand-alone Server

Client x x x

Two-tier Client/Server Server x x

Client x x

Three-tier Client/Server Data Server x

Application Server x

Client x

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3. Requirement Analysis and Specifications

3.1 Requirement Specifications

Every information system development project starts with requirement analysis, so does

my project. In fact, requirement analysis allows me not only to understand the operations of

information systems but also to define the design constraints and specifications. As stated above,

during my internship, I analyzed the current information systems, and specified the problem

definitions [2] [3].

Requirement specifications, also known as requirement modeling, involve analyzing the

current systems in terms of input, output, process, performance and security [6]. This usually

follows the top-down approach, starting with the whole departmental structure, and narrowing

down to the detail business operations. Although there are minor requirements in terms input,

output and process, the issues with performance and security create major problems.

The current systems use Microsoft Access Databases, and they are distributed in the local

area network. The database files are shared across the network. Basically, it is a peer-to-peer

processing system.

Workstation Workstation Workstation Workstation

DCS SDS EVS

Figure 2: Current Physical Systems

Performance Problems Current Issues Specifications

Network Traffic High (due to unnecessary file

sharing)

Reduce Network Traffic

Concurrency Cannot update the files at the

same time

Provide Concurrency

Application Crashes Occurs Frequently when

multiple users access the

database at the same time

Avoid Application Crashes

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Security Problems Current Issues Specifications

Data Integrity Problems with some

referential constraints

Provide referential constraints

User Security Controlled by Network

Directory not by the database

system

Provide Database level user

security

From the requirement specifications, it is clear that most of the problems will be solved

by re-implementing the system on Client-Server Architecture. In fact, there are many options

available for the implementation of client-server system. First, the system can be implemented

with MySQLTM

Database Server and Java Application. Second, it can also be implemented with

MS SQL Server and Visual Studio Application.

However, fortunately, through the college, MS SQL Server and MS Visual Studio are

more accessible to me, so I decided to implement the system by choosing Microsoft Platform

instead of Sun Platform. Later, I found that it was a better choice as Visual Studio provides better

system implementation and debugging.

3.2 Project Schedule and Budget

After defining the requirement specifications and the system architecture to be used, I estimated

the project schedule and budget.

Phase Start Date End Date Requirements Analysis and Specification 05/18/2009 08/21/2009 Design 07/22/2009 09/21/2009 Implementation 08/22/2009 11/28/2009 Testing 09/1/2009 4/26/2010 Evaluation and Reports 4/27/2010 5/6/2010

Components Use Cost Actual Cost Microsoft Visio 2007 $89.98 0.00 Microsoft Visual Studio 2005 Enterprise Edition $567.54 0.00 Microsoft SQL Server 2005 Express Edition $0.00 0.00 Total $657.02 0.00

Since the actual cost for the implementation of the project is practically zero, it is feasible to

carry out the project within the time and budget. However, to meet the requirement

specifications, it is important for me to model the systems by using software development

methodologies.

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4. Software Design

Generally, software design involves both logical design and physical design. The

following sections will explain the step-by-step design process I carried out during my software

design phase. Logical design is primarily concerned with modeling the system without

considering how it will be physically implemented. As stated above, SSADM provides logical

designs, from which physical design can be modeled and built. In fact, the physical design is

responsible for transforming the logical design into physical implementation within the design

constraints. The physical design process will be discussed later as it is based on the logical

design process [2] [3].

4.1 Logical Design

According to SSADM, the logical design process involves 3 models to specify the

information system. All models follow the top-down approach and model the systems into

functional modules, interconnected to each other. During my design phase, I iteratively re-

modeled logical models to finally get the following logical design.

4.1.1 Data Flow Diagram

Data Flow Diagram models the data storages and processes of the information system

and their interaction. It defines the system structures of the information system, and how the

system transforms input data into useful information. In brief, DFD tells us what the system

does, but not how it does it [6].

I use Gane and Sarson symbol set. Another popular symbol set is Yourdon symbol set.

There are 5 symbols in DFD: Process, Data Store, Data Flow, and External Entity. A process,

which is represented by rounded rectangular box, contains the business logic or business rules,

and it receives the input data and produce output data according to the business rule. A data flow

defines the path for data to move from one part of information system to another, and it is

represented by a directed arrow. A data store indicates data storage in the information system,

and it is represented by a open rectangle box. Finally, an external is represented by a rectangle

box, and it is used to provide data to the system or to receive output from the system.

Since DFD follows the top-down approach, it starts with the context diagram, a top level

view of an information system. The context diagram defines the system boundary and total input

data flows and output data flows of the system. Also, the context diagram defines the interaction

of the system with the external entities. Once the context diagram is defined, it is further broken

down into diagram zero. Diagram Zero decomposes the context diagram into the processes, the

data stores and the data flows between them.

In my system, there are 5 major processes: Job Initialization, Input Cell, In-House

Detailing, Sublet Detailing and Release Drawings. For each process is further broken down into

smaller units, called functional primitives, which are used to develop the code later.

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Engineering

Administrator

HSSI EGR INFO SYS

Project

Manager

Drawing

Production

Manager

In-House

DetailerPrint Operator

New Job

Contract Info

Estimator

EstimatesNew Shipment

Master

Scheduler

Schedule

Review Shop Drawings

Assign EA/PM

Select IH/SL

Job Information

Specification for

Printing/Scanning

Drawings &

Documents for

Approval & Release

New Contract Drawings

Job/Shipment Reports

0

New Shop Drawings

New Job Address

New Shipment Address

Review Contract Drawings

Shipment Reports

Review Shop Drawings

Shipment Info

Job Status

Shipment Updates

Shipment Info

Job Info

Figure 3: Context Diagram

As we can see, the context diagram defines the system boundary and scope, and all the

interactions between external entities and the system. In fact, the context diagram provides a top-

level view of the system.

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Engineering

Administrator

Project

Manager

Drawing

Production

Manager

In-House

Detailer

EstimatorMaster

Scheduler

In House

Detailing

Input Cell

Job

Shipment

Sublet

Detailing

Release Drawings

2

3

4

5

New Job

U R

Employee

Assign EA/PM

Contract Info

New Shipment

Shop

Drawings

Job

R

U

R

Estimates

Schedule

New Contract DrawingsSelect IH/Sublet

Job Address

Shipment

Address

U

U

R

U

U

Engineering

Administrator

Review Shop Drawings

Shipment Info

Shop

Drawings

U

R

U

Job Information

Job/Shipment Reports

Contract

Drawings

U

Job

Initialization

1R

U

New Shop Drawings

New Shop Drawings

Review Shop Drawings

Review Shop Drawings

New Job Address

New Shipment Address

Print

Operator

Specs for Printing &

Scanning

Engineering

Administrator

Shipment Reports

Shipment Reports

Shipment Reports

R

R

Drawing

Production

Manager

U

U

Print

Operator

Specs for Printing &

Scanning

Job Status

Shipment Updates

Shipment Updates

Shipment Info

Job Info

Update Shipment

U

Review SD

Figure 4: Diagram Zero

The diagram zero breaks the context diagram into processes, data stores, and the data

flows.

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Specify Job

Information

1.1

Get Est Nbr

and Job Req

Date

1.2

Get Contract

Number

1.3

Divide Job

into

Shipments

1.4

Drawing

Production

Manager

New Job

Estimate Number

Contract Number

# of Shipments

Job

U

U

U

U

Assign Project

Manager

1.5

PM/EA U

Estimator

Master

Scheduler

Schedule

Project

Manager

Job Info

Figure 5: Job Initialization Process

Job Initialization process concerns with the initialization of job and starts the whole data

processing of the system.

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Create Job

Address for

New Job

2.1

Create Job

Folder

2.2

Specify

Shipment

Information

2.4

Input Contract

Drawings

2.3

Input

Shipment

Address

2.6

Shipment

Employee

Job

Job Address

Shipment

Address

Contract

Drawings

Decide SL /

IH

2.5

Engineering

Administrators

Drawing

Production

Manager

R

U

New Contract Drawings

U

Job Info

New Job Address

R

SL/IH

New Shipment Address

New Shipment

U

U

R

R

R

R

U

Figure 6: Input Cell Process

The input cell process defines how the engineering administrators input the job and

shipment information to the system.

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Create Shop

Drawings

3.1

Review Shop

Drawings

3.2

Update

Shipment Info

3.3

Engineering

Administrators

Shop

Drawings

Shipment

New Shop Drawings

Shop Drawings Review

Shipment Updates

U

Print

Operators

Print Specs

3.4

Print Specs

Print Specs

In-House

Detailers

Shop Drawings Review

U

UR

Shipment Info

Figure 7: In-House Detailing Process

In-House detailing process starts once the Engineering Administrators issue the drawing

specs to the in-house detailing (usually drafters.) If the drawings are too much to handle, it is

contracted to the sublet-detailers.

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Create Shop

Drawings

4.1

Review Shop

Drawings

4.2

Update

Shipment Info

4.3

Engineering

Administrators

Shop

Drawings

Shipment

New Shop Drawings

Shop Drawings Review

Shipment Update

U

Print

Operators

Print Specs

4.4

Print Specs

Print Specs

U

UR

Figure 8: Sublet Detailing Process

Sublet-detail process is concerned with the processing the drawings information when the

drawings are sublet to the sublet-detailers.

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Review Shop

Drawings

5.1

Close

Shipment and

Job

5.2

Engineering

Administrators

Shipment

Shop

Drawings

Job

Shop Drawings Review

RU

Update Shipment

U

Change Job

Status

5.3

Update Job Status

U

U

Production

Drawing

Manager

Job/Shipment Reports

Shipment Reports

Figure 9: Release Drawings Process

It is the final process which will handle when drawings are complete and approved. Once

the job is complete, its status is changed to from „active‟ to „fabrication‟.

As stated above, Data flow modeling provides the logical system structures, but it does

not describe the data structures and the dynamic behavior of the system. Therefore, it is required

carry out logical data modeling (Entity Relationship Diagram) and entity behavior modeling

(Entity Life History) to get a better understanding of the nature of the system.

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4.1.2 Entity Relationship Diagram

Entity Relationship Diagram defines logical data structure of system [6] [7].

Drawings

PK DrawingsNbr

Addresses

PK AddressID

Employee

PK EmpID

FK1 EmpType

JobAddress

PK,FK2 JobNbr

PK,FK1 JobAddressNumber

ShopDrawingsRevision

PK,FK1 JobNbr

PK,FK1 JobShipmentNbr

PK,FK1 ShopDrawNbr

PK ShopDrawRevisionNbr

JobType

PK JobTypeNbr

Shipment

PK,FK2 JobNbr

PK JobShipmentNbr

FK1 InCharge

EmployeeType

PK EmployeeTypeID

Job

PK JobNbr

FK2 JobTypeNbr

FK1 JobProjectManager

ContractDrawings

PK,FK2 JobNbr

PK ContractDrawingsNbr

FK1 DrawingsNbr

StateCode

ShipmentAddress

PK,FK2 JobNbr

PK,FK2 JobShipmentNbr

PK,FK1 ShipmentAddressNbr

ContractDrawingsRevision

PK,FK1 JobNbr

PK,FK1 DrawingsNbr

PK RevisionNbr

ShopDrawings

PK,FK2 JobNbr

PK,FK2 JobShipmentNbr

PK ShopDrawNbr

FK1 DrawingsNbr

u:C

d:C

u:C

d:C

u:C

d:C

u:C

d:C

u:C

d:C

u:R

d:R

u:C

d:C

u:C

d:C

u:R

d:R

u:C

d:C

u:C

d:C

u:C

d:C

u:R

d:R

u:R

d:R

u:R

d:R

Figure 10: Entity Relationship Diagram

Unlike DFD, ERD approaches the system from different perspective. First, entities used

in the system are defined, such as Employee, Job, Shipment etc. Each entity is then uniquely

identified by an identifier called primary key. Also, each entity contains other data fields known

as attributes. Moreover, an entity can contain the primary key of another entity as a foreign key if

there is a relationship between two entities. In fact, a relationship between two entities is defined

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through primary and foreign keys. Three forms of relationship can exist between two entities:

one-to-one, one-to-many, and many-to-many. For example, Job entity has a one-to-many

relationship with Shipment entity, as each job contains one or more shipments. Also, ERD can be

used to define the data integrity called referential integrity. I will discuss more about referential

integrity in physical design.

4.1.3 Entity Life History Diagram

The dynamic behavior of the system is defined by ELH (Entity Life History) diagram. In

fact, ELH is similar to state transition diagram. Like state transition diagram, the primary goal of

ELH is to describe the dynamic states of the system. First, the primary entity of the information

is defined, and its life history in the system is modeled by using Jack Structure Diagram [6]. The

following diagram describes the different stages of „Job‟ entity throughout its life.

Subselect and

type additional

text here

Archive Job

Subselect and

type additional

text here

Create Job

Address Subselect and

type additional

text here

Create Job

Folder

Subselect and

type additional

text here

Create Contract

Drawings

Subselect and

type additional

text here

Review Contract

Drawings

Subselect and

type additional

text here

Create Shipment

Subselect and

type additional

text hereUpdate Shipment

Subselect and

type additional

text here

Create Shipment

Address

Subselect and

type additional

text hereSublet Subselect and

type additional

text here

In House

Subselect and

type additional

text here

Create Shop

Drawings

Subselect and

type additional

text here

Review Shop

Drawings

Subselect and

type additional

text here

Update Shipment Subselect and

type additional

text here

Create Shop

Drawings

Subselect and

type additional

text here

Review Shop

Drawings

Subselect and

type additional

text here

Update Shipment

Address

Subselect and

type additional

text here

Initialize Job

Figure 11: Entity Life History of Job

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4.2 Physical Design and Implementation

The physical design process is primarily concerned with implementation of the logical

design of the system on the software/hardware platform selected. In fact, physical design is

highly interrelated with the physical implementation, and so the physical implementation is

discussed along with the physical design. According to the requirement specifications, the

system is to run in the client/server environment with MS SQL Server. The graphical illustration

of two-tier client/server implementation is described in the following figure [6] [7] [8].

Workstation Workstation Workstation Workstation

HSSI

Database

MS SQL Server

Figure 12: Two Tier Client/Server Implementation

As a part of physical design consideration, it is important to specify server processes,

client processes, the interaction between server and client, and finally physical data structures of

the system (database).

The logical design, especially DFD, provides the framework of the processes of the

information system. However, the distribution of the processes depends on the software

architecture. In my case, the two-tier client/server architecture, some processes will be

configured as server-side processes and some will be run as client-side processes. Obviously, to

reduce the network traffic, it is important to run computation intensive processes on the client

side and data intensive processes on the server side.

In addition to the processes, the data structures of the system need to be physically

defined. Since all the data stores of the system will reside on MS SQL Server, the database

schema (data structures) has to be implemented on MS SQL Server. The implementation of

database system on SQL server requires the use of ERD as it provides the logical data structures

of the system. Therefore, I divided the physical design process into 2 phases: database design

and application design.

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4.2.1 Database Design and Implementation

Fortunately, the transformation of ERD to the actual database systems is pretty

straightforward. Each entity in ERD represents a data table in database systems. With the MS

SQL Server Management Studio Express, I can easily define the data tables and their

relationships. The following screen-shot shows the data definition of Job Table and the definition

of relationship between Job Table and Shipment Table.

As stated above, there is a one-to-many relationship between Job and Shipment. Each job

has one or more shipments, and job table is the parent table and shipment table is the child table.

In fact, the relationship requires the definition of the referential integrity between two data tables.

There are 2 referential integrity rules: Delete Rule and Update Rule. Delete Rule will be

triggered whenever the record of parent table is deleted. Since the child table is dependent on the

parent table, the deletion of parent table will affect the records of child table. By setting Delete

Rule to cascade, the records of child will be deleted when the record of parent table is deleted.

Similarly, Update Rule is also defined to enforce the reverential integrity. And finally, other

tables are defined, along with the relationships between them.

Figure 13: Job Table Definition and Job-Shipment Relationship Definition

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Figure 14: Database Diagram defined on SQL Server

4.2.2 Application Design and Implementation

Application design is primarily concerned with the development of Visual Basic Data

Application. DFD, in fact, provides the framework for the processes to be developed. The

application design is to transform the DFD into Visual Basic Application. Generally, application

design process follows the top-down approach and it involves a set of design steps:

1) Class Design – to define the infrastructure and components of the application program

2) Screen Design – to define user interface and data input/output

3) Code Design – to define the application logic and data access functions

4) Data Security – to define data and user security

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Class Design is to model the processes in terms of classes and their relationship to each

other. In this way, it provides a blue print for me to understand how processes can be

modularized into components and how they relate to each other. A class is an ADT (Abstract

Data Type) which encapsulates both data and functions. The following figure will show a typical

defination of a class. Each class includes 4 parts: public, protected, private and friend. Both data

and fuctions can be any one of them. Public members (either data or functions) can be

accessesed by other classes. However, private member can be accessed only by its member

functions.

Figure 15: Class Definitions

Generally, each form represents the functional primitives (the lowest level processes) of

DFD. As we can see, „frmJobFolder‟ Class represents the Creating Job Folder Process, and

„frmJobAddress‟ is responsible for creating Job Addresses. Similarly, other processes are defined

in terms of class definitions. Each class includes a set of member functions to perform the

necessary business processes and a set of member data to store the final or intermediate results of

the processes. For example, the GetJobNbr () function is to read the Job Number from the Job

Data Table. A complete class diagram is described in Appendix – A.

23

Screen Design primarily focuses on developing user interfaces and data input/output.

Since data can enter into the system only through user interface, it is also important to make sure

only valid data is entered into the system. A good screen design has to provide user-friendly

interface and rigorous data validation checks. I use MDI (Multiple Document Interface) for the

screen design. In MDI, the main form acts as a container for displaying other documents and

forms inside it.

Figure 16: Multiple Document Interface

The following figure shows the screen design for the Shipment „Form‟. It includes a set

of Combo Boxes, Text Boxes, Check Boxes and Control Buttons for the user to enter the data

and to process the data.

Figure 17: „Shipment Form‟ Screen Design

24

Code design involves developing the client program with VB.Net language, and the

server program with stored procedures on SQL Server. Since most of the processes are

computational intensive processes, the majority of processes are implemented on the client

application. However, as stated above, some of the processes will be configured as server-side

processes on SQL Server.

Generally, the operation of client/server program can be described as follow. In order to

perform data processing, the client application will request the data access (with SQL

Statements) to the database stored on SQL Server. Once the Server receives the data request, it

responses the client by providing necessary data. When the client receives the necessary data, it

processes the necessary data processing and stores the results back on the Server [6] [7][8].

In fact, VB.net provides a set of objects, called SQL-Client objects, to provide data

access functionality for the client processes. SQL Client objects will enable the client software to

access to the MS SQL Server through SQL-connection object. Once the SQL-connection is

established, the client can access to the database on SQL Server.

Figure 18: SQL-Client Objects

25

The following code segment shows how to connect to the SQL Server with

connection string.

Private Function dbConnect(ByVal UsrName As String, ByVal Pwd As String,

ByVal LocalAuth As Boolean) As Boolean

Dim ConnectionString As String

If LocalAuth = True Then

ConnectionString = "Data Source=CYBVIC\SQLEXPRESS;Initial Catalog

=HSSI; Integrated Security=True;"

Else

ConnectionString = "Data Source=CYBVIC\SQLEXPRESS;Initial

Catalog=HSSI;Integrated Security=False;" & ";User ID=" & _

txtUsrName.Text & ";Password=" & txtPwd.Text & ";"

End If

Try

frmMain.dbConnection.ConnectionString = ConnectionString

frmMain.dbConnection.Open()

The following code segment is to import the system library files to for SQL-

Client Objects.

Imports System

Imports System.Data

Imports System.Data.SqlClient

The following code segment is the class definition of frmAddress Class. The

SQL statemet are defined as private constant members of the class. Also

DataAdpater Object, DataSet Object, DataTable Object and DataRow Object are

defined as private data members.

Public Class frmAddress

'SQL Statement for accessing SQL Server

Const SQL_ADDRESS = "SELECT * FROM dbo.Addresses ORDER BY AddressID"

Const SQL_JOBADDRESS = "SELECT * FROM dbo.Addresses WHERE AddressID = "

Const SQL_STATE = "SELECT StateCode FROM dbo.StateCode"

Private dbDataAdapter As SqlDataAdapter

Private dbDataSet As New DataSet

Private dbDataTable As DataTable

Private dbDataRow As DataRow

Private dbNew As Boolean

Public key As String

26

The following code will show how DataAdapter object is created and how it is

processed to get acces to the database.

Private Sub UpdateAddress()

'Assign primary keys for seeking the specific record

Try

dbDataAdapter = New SqlDataAdapter(SQL_ADDRESS, frmMain.dbConnection)

dbDataAdapter.FillSchema(dbDataSet, SchemaType.Source, "dbo.Addresses")

dbDataAdapter.Fill(dbDataSet, "dbo.Addresses")

dbDataTable = dbDataSet.Tables("dbo.Addresses")

If dbNew Then

dbDataRow = dbDataTable.NewRow()

dbDataRow("AddressID") = txtAddressID.Text

dbDataRow("LastName") = txtLastName.Text

…

dbDataTable.Rows.Add(dbDataRow)

dbNew = False

In addition to the client processes, it is necessary to implement some processes, such as

Creating User Logins, Creating Security Policies etc, on SQL Server. Fortunately, the SQL

Server provides a programming functionality called Stored Procedure to develop the server-side

processes. Also, SQL Server provides built-in stored procedures for common server operations

related to user and data Securities, data definitions and data manipulations.

The following code segment is to request the Server from the Client to run

the sever-side stored procedure called “sys.sp_addlogin”, which is to add a

login profile for a user.

SQLCmd = New SqlCommand

SQLCmd.CommandText = "sys.sp_addlogin"

SQLCmd.CommandType = CommandType.StoredProcedure

SQLCmd.Connection = frmMain.dbConnection

SQLCmd.Parameters.AddWithValue("@loginame", txtLogin.Text)

SQLCmd.Parameters.AddWithValue("@passwd", txtComfirmPwd.Text)

SQLCmd.Parameters.AddWithValue("@defdb", "HSSI")

SQLCmd.ExecuteNonQuery()

SQLCmd.Dispose()

27

As stated above, one of the requirement specifications is to enhance data and user

securities. Therefore, defining user and data securities is as important as developing the

application. Generally, security definition can be divided into login authentication and group

policy. The following table shows the user group definitions for each user type.

1 Manager

db_owner

2 Engineering Administrator

db_ddladmin

3 Project Manager

db_accessadmin

4 Engineering Technician

db_datawriter

5 Drafter

db_datareader

6 N/A

public

The users are usually categorized into Manager, Engineering Administrator, Project

Manager, Engineering Technician, Drafter and N/A. Depending on the user type, the data access

to the database is restricted. For example, Drafter cannot update nor delete the data. In fact, user

group policies enforce the data restriction on users.

In addition to group policy, each user requires user authentication to access to the

database. For that, each authenticated user is provided with a set of password and username to

access to the database.

Figure 19: User Authentication

28

Figure 20: User Profiles

Figure 21: User Profile Settings

29

5. Testing and Evaluation

Once the software development is complete, I carried out a series of tests to evaluate the

performance and reliable of the program. The results screen shots are shown below.

Figure 22: Data Validation Check

Figure 23: Shop Drawings Data Entry

30

Figure 24: Job Summary Report

31

5. Conclusion

Information is the essential part of organizations, and information systems are necessary

for the survival of the organizations. It is not uncommon that inefficiency of information systems

leads to the failure of business. More importantly, information systems have a huge impact on

the ethical and social issues of the operation of the business. Lack of data security and data

integrity can raise ethical issues in the organization. A common example would be the

unauthorized access to the sensitive information. Also, chaotic interaction between each

information system can result in problematic social communications among the workforce of the

organizations. Therefore, many organizations have implemented and standardized the system

development methodologies to ensure to deliver the efficient software information systems to the

organizations. Still, both the information and the software, by nature, are intangible; sometimes,

it is difficult to reach the perfect understanding of them, even with the systematic software

development and engineering principles.

As stated above, my primary goal for the senior project is to understand the software

development principles as much as I can and to apply them to develop a working application. To

this extent, I fulfill the goal of the project as I can successfully build the software application by

following the software development principles.

However, it is always possible to improve the software in many ways. First, the report

generation tool I used for the project is the intrinsic data report tool, which is part of MS Visual

Studio, and it can only provide static reporting. In fact, static reporting requires the data-set to be

statically bounded with the data sources in the design time. It cannot allow dynamic binding at

the run-time. Therefore, new solutions are required to handle dynamic reporting. Second, the

project is based on the simplified model of the HSSI information system. It does not cover all the

functionality of the system, although it serves as a prototype of the client/server implementation

of the system. Therefore, the additional features will make a better software system.

32

References

[1] Software Engineering Institute. “How we approach software development.” CMU, Carnegie Mellon

University, 2010. Web 5 May, 2010. http://www.sei.cmu.edu/solutions/softwaredev/

[2] Allan M. Davis, Edward H. Bersoff, and Edward R. Comer. "A Strategy for Comparing Alternative

Software Development Life Cycle Models." IEEE Transaction on Software Engineering 14.8

(1988): Web. 5 May 2010.

[3] Simon Rogerson, John Weckert, and Chris Simpson. “An ethical review of information systems

development.” Information Technology and People 13.2 (2000): Web 5 May 2010.

[4] Klaus Bergner, Andreas Rausch, and Marc Sihling. “Using UML for Modeling a Distributed Java

Application.” Institut fur Informatik Techniche Universitat Muchen (1997): Web. 5 May 2010.

[5] M. Tamer Ozsu. “Distributed Database Systems.” University of Waterloo, Department of Computer

Science (2002): Web. 5 May 2010.

[6] Shelly, Gary B., Thomas J. Cashman, and Harry J. Rosenblatt. Systems Analysis and Design. 7th

Edition. Boston: Thomson Course Technology, Print.

[7] Connolly, Thomas M., and Carolyn E. Begg. Database Systems. 4th Edition. Essex: Pearson

Education Limited, 2005. Print.

[8] Carey, Michael J., et al. "Data Caching Tradeoffs in Client Server DBMS Architectures." (1991):

Web. 5 May 2010.

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Appendix – A