10 thing 10: information Systems Development

Dave Bourgeois and David T. Bourgeois

Please note, over there is one updated edition of this book obtainable at https://opentextbook.site. If you are not forced to use this edition because that a course, you might want to check it out.You room watching: ____ concentrates on point out what the brand-new system will certainly look like and how it will certainly work.

You are watching: ____ focuses on specifying what the new system will look like and how it will work.

Learning Objectives

Upon effective completion that this chapter, you will be able to:

explain the overall procedure of emerging a new software application;explain the differences in between software advance methodologies;understand the different species of programming languages offered to construct software;understand some of the problems surrounding the advance of websites and also mobile applications; andidentify the four primary implementation policies.

Introduction

When someone has an idea because that a brand-new function to be performed by a computer, just how does that idea become reality? If a company wants come implement a new business procedure and needs new hardware or software program to support it, exactly how do lock go about making it happen? In this chapter, us will discuss the different methods of acquisition those ideas and also bringing them come reality, a procedure known as information systems development.

Programming

As we learned in chapter 2, software application is created via programming. Programming is the process of developing a set of logical instructions because that a digital machine to follow using a programming language. The process of programming is sometimes dubbed “coding” because the syntax that a programming language is not in a kind that everyone have the right to understand – that is in “code.” 

The procedure of developing good software is commonly not as straightforward as sitting down and also writing part code. True, sometimes a programmer can easily write a quick program to settle a need. However most of the time, the production of software is a resource-intensive procedure that entails several different groups of people in one organization. In the complying with sections, we space going to testimonial several various methodologies for software program development.

Systems-Development Life Cycle

The first development methodology we space going to evaluation is the systems-development life bicycle (SDLC). This methodology was very first developed in the 1960s to control the huge software projects linked with corporate systems running ~ above mainframes. The is a an extremely structured and risk-averse methodology designed come manage huge projects that consisted of multiple programmers and systems that would have actually a huge impact on the organization.


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SDLC waterfall (click come enlarge)

Various interpretations of the SDLC methodology exist, however most save the adhering to phases.

Preliminary Analysis. In this phase, a review is done of the request. Is creating a systems possible? What options exist? What is at this time being done around it? Is this project a an excellent fit because that our organization? A key part that this step is a feasibility analysis, which has an evaluation of the technological feasibility (is it possible to create this?), the economic feasibility (can we afford to perform this?), and the legal feasibility (are we permitted to do this?). This step is crucial in determining if the project should also get started.System Analysis. In this phase, one or more system experts work with various stakeholder teams to identify the specific requirements for the new system. No programming is done in this step. Instead, steps are documented, crucial players space interviewed, and also data demands are emerged in bespeak to acquire an overall picture of exactly what the device is an alleged to do. The an outcome of this phase is a system-requirements document.System Design. In this phase, a designer bring away the system-requirements document created in the previous phase and also develops the specific technical details compelled for the system. That is in this phase that the business requirements are analyzed into specific technical requirements. The design for the user interface, database, data inputs and outputs, and reporting are developed here. The an outcome of this step is a system-design document. This file will have every little thing a programmer will must actually produce the system.Programming. The code ultimately gets composed in the programming phase. Using the system-design document as a guide, a programmer (or team that programmers) develop the program. The result of this phase is an initial working routine that meets the needs laid out in the system-analysis phase and the architecture developed in the system-design phase.Testing. In the testing phase, the software program program emerged in the previous step is placed through a series of structured tests. The first is a unit test, i m sorry tests individual components of the code for errors or bugs. Next is a mechanism test, whereby the different materials of the device are experiment to ensure that they occupational together properly. Finally, the user-acceptance test allows those that will certainly be using the software to check the device to ensure that it meets their standards. Any type of bugs, errors, or troubles found throughout testing room addressed and then experiment again.Implementation. Once the new system is developed and also tested, it needs to be imposed in the organization. This phase includes training the users, giving documentation, and also conversion from any previous system to the brand-new system. Implementation can take countless forms, depending upon the type of system, the number and kind of users, and also how immediate it is the the system become operational. These various forms of implementation are covered later in the chapter.Maintenance. This final phase takes ar once the implementation step is complete. In this phase, the system has actually a structured support process in place: reported bugs are fixed and requests for brand-new features are evaluated and implemented; mechanism updates and also backups space performed ~ above a consistent basis.

The SDLC methodology is periodically referred to together the waterfall methodology to represent just how each step is a separate part of the process; only when one step is completed can an additional step begin. After every step, an organization should decide whether to relocate to the next step or not. This methodology has actually been criticized because that being quite rigid. For example, alters to the requirements are not allowed once the procedure has begun. No software program is available until after the programming phase.

Again, SDLC was emerged for large, structured projects. Jobs using SDLC deserve to sometimes take months or year to complete. Due to the fact that of the inflexibility and the accessibility of new programming techniques and also tools, plenty of other software-development methodologies have been developed. Countless of these retain few of the underlying ideas of SDLC however are no as rigid.

Rapid applications Development


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The RAD methodology (Public Domain)

Rapid application breakthrough (RAD) is a software-development (or systems-development) methodology that concentrates on quickly building a working design of the software, gaining feedback indigenous users, and then using that feedback to update the functioning model. After number of iterations of development, a last version is developed and implemented.

The RAD methodology consists of 4 phases:

Requirements Planning. This step is similar to the preliminary-analysis, system-analysis, and design phases that the SDLC. In this phase, the in its entirety requirements for the system are defined, a team is identified, and feasibility is determined. User Design. In this phase, to represent of the users occupational with the system analysts, designers, and also programmers come interactively produce the design of the system. One method for working with all of these various stakeholders is the so-called JAD session. JAD is one acronym for joint applications development. A JAD conference gets all of the stakeholders with each other to have a structured discussion about the architecture of the system. Application developers also sit in top top this meeting and observe, do the efforts to recognize the significance of the requirements.Construction. In the construction phase, the application developers, working v the users, build the following version of the system.This is an interactive process, and also changes have the right to be made as developers room working ~ above the program. This action is enforcement in parallel with the User architecture step in an repeat fashion, till an acceptable version of the product is developed. Cutover. In this step, i m sorry is similar to the implementation action of the SDLC, the mechanism goes live. All steps forced to relocate from the previous state come the usage of the new system space completed here.

As you can see, the RAD methodology is much much more compressed 보다 SDLC. Many of the SDLC procedures are an unified and the focus is top top user participation and also iteration. This methodology is much better suited for smaller jobs than SDLC and also has the included advantage of offering users the capability to carry out feedback throughout the process. SDLC requires much more documentation and also attention to detail and is fine suited come large, resource-intensive projects. RAD makes more sense for smaller projects that are less resource-intensive and need come be developed quickly.

Agile Methodologies

Agile methodologies space a team of methodologies that use incremental transforms with a emphasis on quality and also attention come detail. Every increment is released in a specified period of time (called a time box), developing a continual release schedule v very particular objectives. While considered a separate methodology indigenous RAD, lock share few of the exact same principles: repeat development, user interaction, capacity to change. The agile methodologies are based upon the “Agile Manifesto,” an initial released in 2001.

The attributes of agile techniques include:

small cross-functional groups that encompass development-team members and users; daily status meetings to discuss the present state the the project;short time-frame increments (from days to one or two weeks) for each readjust to it is in completed; andat the end of every iteration, a working task is completed to show to the stakeholders.

The score of the agile methodologies is to administer the flexibility of an iterative method while ensuring a quality product.

Lean Methodology


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The skinny methodology (click come enlarge)

One critical methodology us will talk about is a relatively new concept taken native the organization bestseller The lean Startup, by Eric Reis. In this methodology, the focus is on acquisition an early idea and also developing a minimum viable product (MVP). The MVP is a working software application application through just enough functionality to demonstrate the idea behind the project. When the MVP is developed, that is offered to potential customers for review. Feedback ~ above the MVP is generated in two forms: (1) direct observation and also discussion with the users, and (2) consumption statistics gathered indigenous the software program itself. Using these two creates of feedback, the team determines whether they should continue in the very same direction or rethink the main point idea behind the project, readjust the functions, and also create a new MVP. This change in strategy is referred to as a pivot. Several iterations of the MVP are developed, with new functions included each time based on the feedback, until a last product is completed.

The greatest difference in between the skinny methodology and the various other methodologies is the the full collection of demands for the device are not well-known when the task is launched. As each iteration of the job is released, the statistics and also feedback gathered are provided to identify the requirements. The skinny methodology works ideal in one entrepreneurial atmosphere where a firm is interested in identify if your idea because that a software application application is precious developing.

Sidebar: The quality Triangle
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The top quality triangle

When developing software, or any kind of sort the product or service, there exists a tension in between the developers and the different stakeholder groups, such as management, users, and investors. This anxiety relates to how conveniently the software deserve to be arisen (time), how much money will be invested (cost), and also how fine it will be developed (quality). The top quality triangle is a simple concept. It claims that for any type of product or service being developed, you can only address two that the following: time, cost, and also quality.

So what go it typical that you have the right to only attend to two the the three? It way that girlfriend cannot complete a low-cost, high-quality project in a tiny amount of time. However, if you room willing or able to spend a many money, climate a project can be completed easily with high-quality results (through rental more great programmers). If a project’s completion day is no a priority, then it can be completed at a lower cost with higher-quality results. That course, this are simply generalizations, and different projects might not to the right this version perfectly. However overall, this version helps us understand the tradeoffs the we should make once we are developing new products and also services.

Programming Languages

As I provided earlier, software developers produce software using among several programming languages. A programming language is an man-made language that offers a way for a programmer to produce structured code to connect logic in a layout that can be enforcement by the computer system hardware. Over the past few decades, plenty of different varieties of programming language have developed to meet many different needs. One way to characterize programming languages is by their “generation.”

Generations the Programming Languages

Early language were particular to the kind of hardware that had to be programmed; each kind of computer system hardware had a various low-level programming language (in fact, even today there are differences at the reduced level, though they are now obscured by higher-level programming languages). In these early languages, very particular instructions had to be entered line by line – a tedious process.

First-generation languages room called an equipment code. In maker code, programming is done by directly setup actual ones and also zeroes (the bits) in the regimen using binary code. Right here is an example program that to add 1234 and also 4321 using maker language:

10111001 0000000011010010 1010000100000100 0000000010001001 0000000000001110 1000101100000000 0001111000000000 0001111000000000 0000001010111001 0000000011100001 0000001100010000 1100001110001001 1010001100001110 0000010000000010 00000000Assembly language is the second-generation language. Assembly language gives english-like phrases come the machine-code instructions, making it much easier to program. An assembly-language program should be run through an assembler, which converts it into machine code. Right here is an instance program the adds 1234 and 4321 using assembly language:

MOV CX,1234MOV DS:,CXMOV CX,4321MOV AX,DS:MOV BX,DS:ADD AX,BXMOV DS:,AXThird-generation languages space not details to the kind of hardware on which castle run and also are much much more like spoken languages. Many third-generation languages have to be compiled, a process that converts lock into an equipment code. Famous third-generation languages encompass BASIC, C, Pascal, and also Java. Right here is an instance using BASIC:

A=1234B=4321C=A+BENDFourth-generation languages room a class of programming devices that allow fast application advance using intuitive interfaces and environments. Plenty of times, a fourth-generation language has a very particular purpose, such as database communication or report-writing. This tools can be provided by those v very tiny formal maintain in programming and allow for the quick advancement of applications and/or functionality. Examples of fourth-generation language include: Clipper, FOCUS, FoxPro, SQL, and also SPSS.

Why would anyone want to routine in a lower-level language once they need so much more work? The prize is comparable to why some like to drive stick-shift automobiles instead of automatic transmission: control and efficiency. Lower-level languages, such as assembly language, are much much more efficient and execute much much more quickly. You have finer regulate over the hardware together well. Sometimes, a combination of higher- and also lower-level language are mixed together to gain the best of both worlds: the programmer will create the overall structure and also interface using a higher-level language however will usage lower-level languages because that the parts of the regimen that room used numerous times or require much more precision.


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The programming language spectrum (click to enlarge)

Compiled vs. Interpreted

Besides classifying a regime language based upon its generation, that can also be classified by even if it is it is compiled or interpreted. Together we have learned, a computer system language is created in a human-readable form. In a compiled language, the routine code is interpreted into a machine-readable kind called one executable that can be operation on the hardware. Some renowned compiled languages include C, C++, and also COBOL.

An construed language is one that needs a runtime program to be mounted in order come execute. This runtime program then interprets the routine code line through line and runs it. Understood languages are generally easier to job-related with but likewise are slower and also require more system resources. Instances of popular construed languages incorporate BASIC, PHP, PERL, and Python. The net languages the HTML and Javascript would additionally be considered interpreted because they require a web browser in order come run.

The Java programming language is an interesting exception to this classification, together it is in reality a hybrid of the two. A regime written in Java is partly compiled to produce a program that can be understood by the Java Virtual an equipment (JVM). Each type of operating system has its own JVM which should be installed, i m sorry is what enables Java program to run on numerous different varieties of operating systems.

Procedural vs. Object-Oriented

A procedural programming language is design to allow a programmer to define a certain starting suggest for the program and also then execute sequentially. All at an early stage programming languages operated this way. Together user interfaces became much more interactive and graphical, the made sense for programming language to evolve to permit the user to define the circulation of the program. The object-oriented programming language is set up so that the programmer specifies “objects” that deserve to take particular actions based upon input indigenous the user. In various other words, a procedural program focuses on the succession of tasks to be performed; one object-oriented program concentrates on the different items gift manipulated.

For example, in a human-resources system, one “EMPLOYEE” object would be needed. If the program essential to retrieve or set data regarding an employee, it would very first create an employee object in the program and then set or retrieve the values needed. Every object has properties, which are descriptive fields connected with the object. In the example below, an employee object has actually the nature “Name”, “Employee number”, “Birthdate” and also “Date that hire”. One object also has “methods”, which deserve to take actions regarded the object. In the example, there space two methods. The first is “ComputePay()”, which will certainly return the existing amount owed the employee. The 2nd is “ListEmployees()”, which will certainly retrieve a perform of employees that report come this employee.

Object: EMPLOYEE
NameEmployee numberBirthdateDate of hire
ComputePay()ListEmployees()

Figure: an example of one object

Sidebar: What is COBOL?

If you have actually been roughly business programming very long, friend may have actually heard about the COBOL programming language. COBOL is a procedural, compiled language that at once was the major programming language for service applications. Developed in 1959 for use on large mainframe computers, COBOL is an abbreviation of typical business-oriented language. V the arrival of an ext efficient programming languages, COBOL is currently rarely seen outside of old, heritage applications.

Programming Tools

To create a program, a programmer needs little more than a text editor and a great idea. However, to be productive, the or she must have the ability to check the syntax of the code, and, in part cases, compile the code. Come be much more efficient in ~ programming, extr tools, such as an integrated advance environment (IDE) or computer-aided software-engineering (CASE) tools, deserve to be used.

Integrated advancement Environment

For many programming languages, an principle can it is in used. An concept provides a range of tools for the programmer, and usually includes:

an editor for composing the regime that will color-code or to mark keywords indigenous the programming language;a assist system that gives thorough documentation concerning the programming language;a compiler/interpreter, i beg your pardon will enable the programmer to operation the program;a debugging tool, i m sorry will carry out the programmer details around the execution that the regime in order come resolve problems in the code; anda check-in/check-out mechanism, which allows for a team of programmers to work together top top a project and also not create over each other’s code changes.

Probably the most popular principle software package right now is Microsoft’s visual Studio. Intuitive Studio is the ide for all of Microsoft’s programming languages, consisting of Visual Basic, visual C++, and also Visual C#.

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CASE Tools

While an principle provides several tools to aid the programmer in composing the program, the password still have to be written. Computer-aided software-engineering (CASE) tools enable a designer to construct software with tiny or no programming. Instead, the case tool writes the password for the designer. CASE devices come in countless varieties, but their goal is come generate high quality code based on input developed by the designer.

Sidebar: structure a Website

In the beforehand days of the World vast Web, the creation of a website compelled knowing how to use hypertext markup language (HTML). Today, many websites are built with a selection of tools, yet the last product the istransfer come a web browser is still HTML. HTML, in ~ its simplest, is a message language that permits you to define the different components of a internet page. These definitions are taken on through the use of HTML tags, which consist of text in between brackets. Because that example, an HTML tag deserve to tell the browser to present a native in italics, to link to another web page, or come insert one image. In the instance below, some message is being defined as a heading while various other text is gift emphasized.