10.3: Software Development
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- Ly-Huong T. Pham, Tejal Desai-Naik, Laurie Hammond, & Wael Abdeljabbar
- ASCCC Open Educational Resources Initiative (OERI)
Software Development
Many of the methodologies discussed above are used to manage software development since programming is complex, and sometimes errors are hard to detect. We learned in chapter 2 that software is created via programming, and programming is the process of creating a set of logical instructions for a digital device to follow using a programming language. The programming process is sometimes called “coding” because the syntax of a programming language is not in a form that everyone can understand – it is in “code.”
The process of developing good software is usually not as simple as sitting down and writing some code. True, sometimes a programmer can quickly write a short program to solve a need. But most of the time, the creation of software is a resource-intensive process that involves several different groups of people in an organization. In the following sections, we are going to review several different methodologies for software development.
Sidebar: The project management quality triangle
When developing software or any product or service, there is tension between the developers and the different stakeholder groups, such as management, users, and investors. Fig. 10.5 illustrates the tension of the three requirements: time, cost, and quality that project managers need to make tradeoffs in. From how quickly the software can be developed (time), to how much money will be spent (cost), to how well it will be built (quality). The quality triangle is a simple concept. It states that you can only address two of the following: time, cost, and quality for any product or service being developed.
So what does it mean that you can only address two of the three? It means that the finished product's quality depends on the three variables: scope, schedule, and the allocated budget. Changes in any of these three variables affect the other two, hence, the quality.
For example, if a feature is added, but no additional time is added to the schedule to develop and test, the code's quality may suffer, even if more money is added. There are times when it is not even feasible to make the tradeoff. For example, adding more people to a project where members are so overwhelmed that they don’t have time to manage or train new people. Overall, this model helps us understand the tradeoffs we must make when developing new products and services.
Programming Languages
One of the important decisions that a project team needs to make is to decide which programming language(s) are to be used and associated tools in the development process. As mentioned in chapter 3, software developers create software using one of several programming languages. A programming language is a formal language that provides a way for a programmer to create structured code to communicate logic in a format that the computer hardware can execute. Over the past few decades, many different programming languages have evolved to meet many different needs.
There is no one way to categorize the languages. Still, they are often grouped by type (i.e., query, scripting), or chronologically by year when it was introduced (i.,e. Fortran was introduced in 1954s), by their “generation,” by how it was translated to the machine code, or how it was executed. We will discuss a few categories in this chapter.
Generations of Programming Languages
Early languages were specific to the type of hardware that had to be programmed; each type of computer hardware had a different low-level programming language (in fact, even today, there are differences at the lower level, though higher-level programming languages now obscure them). In these early languages, precise instructions had to be entered line by line – a tedious process.
Some common characteristics are summarized below to illustrate some differences among these generations:
|
First-generation (1GL) |
Second-generation (2GL) |
Third-generation (3GL) |
Fourth-generation (4GL) |
Fifth-generation (5GL) |
|
|---|---|---|---|---|---|
|
Time introduced (est). |
1940s or earlier |
1950s |
1950s-1970s |
1970s-1990s |
1980s-1900s |
|
Instructions |
They are made of binary numbers of 0s and 1s |
Use a set of syntax that is readable by human and programmers |
The syntax is more structured and is made up of more human-like language |
The syntax is friendly to non-programmers |
Still in progress. |
|
Category |
Machine dependent Machine code |
Machine dependent Low level, Assembly Languages |
Machine independent High Level |
Machine independent High-level abstraction, Advanced 3GLs |
Logic programming |
|
Advantage |
Very fast, no need for ‘translation’ to 0s and 1s |
Code can be read and written by programmers easier than learning machine code |
More machine-independent More friendly to programmers General-purpose |
Easy to learn |
May not need programmers to write programs |
|
Disadvantage |
Machine dependent, not portable |
Must be converted to machine code, still machine-dependent |
May go multiple steps to translate to machine code |
More specialized |
Still early in the adoption phase |
|
Today’s usage |
If needed to interact with hardware directly such as drivers (i.e., USB driver) |
If needed to interact with hardware directly such as drivers (i.e., USB driver) |
Modern 3GLs are more commonly used. Early 3GLs are used to maintain existing business programs or scientific programs |
Database, web development |
Limited Visual tools, Artificial intelligence research |
|
Examples |
Machine language |
Assembly language |
Early 3GLs: COBOL, Fortran Modern 3PLs: C, C++, Java, Javascript |
Perl, PhP, Python, SQL, Ruby |
Mercury, OPS5 |
Statista.com reported that by early 2020, Javascript was the most used language among developers worldwide. To see the complete list, please v isit Statista.com for more details.
Sidebar: Examples of languages
First-generation language: machine code. In machine code, programming is done by directly setting actual ones and zeroes (the bits) using binary code. Here is an example program that
adds 1234 and 4321 using machine language:
|
10111001 |
00000000 |
|
11010010 |
10100001 |
|
00000100 |
00000000 |
|
10001001 |
00000000 |
|
00001110 |
10001011 |
|
00000000 |
00011110 |
|
00000000 |
00011110 |
|
00000000 |
00000010 |
|
10111001 |
00000000 |
|
11100001 |
00000011 |
|
00010000 |
11000011 |
|
10001001 |
10100011 |
|
00001110 |
00000100 |
|
00000010 |
00000000 |
Second-generation language . Assembly language gives English-like phrases to the machine-code instructions, making it easier to program. An assembly-language program must be run through an assembler, which converts it into machine code. Here is an example program that adds 1234 and 4321 using assembly language:
MOV CX,1234 MOV DS:[0],CX MOV CX,4321 MOV AX,DS:[0]
MOV BX,DS:[2] ADD AX,BX
MOV DS:[4],AX
Third-generation languages are not specific to the type of hardware they run and are much more like spoken languages. Most third-generation languages must be compiled, a process that converts them into machine code. Well-known third-generation languages include BASIC, C, Pascal, and Java. Here is an example using BASIC:
A=1234 B=4321 C=A+B END
Fourth-generation languages are a class of programming tools that enable fast application development using intuitive interfaces and environments. Many times, a fourth-generation language has a particular purpose, such as database interaction or report-writing. These tools can be used by those with very little formal training in programming and allow for the quick development of applications and/or functionality. Examples of fourth-generation languages include Clipper, FOCUS, FoxPro, SQL, and SPSS.
Why would anyone want to program in a lower-level language when they require so much more work? The answer is similar to why some prefer to drive stick-shift automobiles instead of automatic transmission: control and efficiency. Lower-level languages, such as assembly language, are much more efficient and execute much more quickly. You have finer control over the hardware as well. Sometimes, a combination of higher- and lower-level languages is mixed together to get the best of both worlds: the programmer will create the overall structure and interface using a higher-level language but will use lower-level languages wherever in the program that requires more precision.
Compiled vs. Interpreted
Besides classifying a programming language based on its generation, it can also be classified as compiled or interpreted language. As we have learned, a computer language is written in a human-readable form. In a compiled language, the program code is translated into a machine-readable form called an executable that can be run on the hardware. Some well-known compiled languages include C, C++, and COBOL.
An interpreted language requires a runtime program to be installed to execute. This runtime program then interprets the program code line by line and runs it. Interpreted languages are generally easier to work with but are slower and require more system resources. Examples of popular interpreted languages include BASIC, PHP, PERL, and Python. The web languages such as HTML and Javascript would also be considered interpreted because they require a browser to run.
The Java programming language is an interesting exception to this classification, as it is actually a hybrid of the two. A program written in Java is partially compiled to create a program that can be understood by the Java Virtual Machine (JVM). Each type of operating system has its own JVM, which must be installed, allowing Java programs to run on many different types of operating systems.
Procedural vs. Object-Oriented
A procedural programming language is designed to allow a programmer to define a specific starting point for the program and then execute sequentially. All early programming languages worked this way. As user interfaces became more interactive and graphical, it made sense for programming languages to evolve to allow the user to define the program's flow. The object-oriented programming language is set up to define “objects” that can take certain actions based on user input. In other words, a procedural program focuses on the sequence of activities to be performed; an object-oriented program focuses on the different items being manipulated.
For example, in a human-resources system, an “EMPLOYEE” object would be needed. If the program needed to retrieve or set data regarding an employee, it would first create an employee object in the program and then set or retrieve the values needed. Every object has properties, which are descriptive fields associated with the object. In the example below, an employee object has the properties “Name,” “Employee number,” “Birthdate,” and “Date of hire.” An object also has “methods,” which can take actions related to the object. In the example, there are two methods. The first is “ComputePay(),” which will return the current amount owed to the employee. The second is “ListEmployees(),” which will retrieve a list of employees who report to this employee.
Employee Object
|
Object: EMPLOYEE |
|
First_Name Last_Name Employee_ID Birthdate Date_of_hire |
|
ComputePay() ListEmployees() |
Programming Tools
Another decision that needs to be made during the development of an IS is the set of tools needed to write programs. To write programs, programmers need tools to enter code, check for the code's syntax, and some method to translate their code into machine code. To be more efficient at programming, programmers use integrated tools such as an integrated development environment (IDE) or computer-aided software-engineering (CASE) tools.
Integrated Development Environment (IDE)
For most programming languages, an IDE can be used. An IDE provides various tools for the programmer, all in one place with a consistent user interface. IDE usually includes:
- an editor for writing the program that will color-code or highlight keywords from the programming language;
- a help system that gives detailed documentation regarding the programming language;
- a compiler/interpreter, which will allow the programmer to run the program;
- a debugging tool, which will provide the programmer details about the execution of the program to resolve problems in the code; and
- a check-in/check-out mechanism allows a team of programmers to work together on a project and not write over each other’s code changes.
Statista.com reports that 80% of software developers worldwide from 2018 and 2019 use a source code collaboration tool such as GitHub, 77% use a standalone IDE such as Eclipse, 69% use Microsoft Visual Studio. For a complete list, please visit statista.com .
Computer-aided software engineering (CASE) Tools
While an IDE provides several tools to assist the programmer in writing the program, the code still must be written. Computer-aided software engineering (CASE) tools allow a designer to develop software with little or no programming. Instead, the CASE tool writes the code for the designer. CASE tools come in many varieties, but their goal is to generate quality code based on the designer's input.
Build vs. Buy or Subscribe
When an organization decides that a new software program needs to be developed, they must determine if it makes more sense to build it themselves or purchase it from an outside company. This is the “build vs. buy” decision. This ‘buy’ decision now includes the option to subscribe instead of buying it outright.
There are many advantages to purchasing software from an outside company. First, it is generally less expensive to purchase a software package than to build it. Second, when a software package is purchased, it is available much more quickly than if the package is built in-house. Third, companies or consumers pay a one-time price and get to keep the software for as long as the license allows and could be as long as you own it or even after the vendor stops supporting it. Software applications can take months or years to build; a purchased package can be up and running within a month. A purchased package has already been tested, and many of the bugs have already been worked out, and additional support contracts can be purchased. It is the role of a systems integrator to make various purchased systems and the existing systems at the organization work together.
There are also disadvantages to purchasing software. First, the same software you are using can be used by your competitors. If a company is trying to differentiate itself based on a business process in that purchased software, it will have a hard time doing so if its competitors use the same software. Another disadvantage to purchasing software is the process of customization. If you purchase a software package from a vendor and then customize it, you will have to manage those customizations every time the vendor provides an upgrade. With the rise of security and privacy, companies may lack the in-house expertise to respond quickly. Installing various updates and dealing with bugs encountered may also be a burden to IT staff and users. This can become an administrative headache.
A hybrid solution is to subscribe. Subscribe means that instead of selling products individually, vendors now offer a subscription model that the users can rent and pay periodically, such as monthly, yearly. The renting model has been used in many other industries such as movies, books and recently has moved into high tech industries. Companies and consumers can now subscribe to almost everything, as we discussed in earlier chapters, from additional storage in your email platforms such as Google Drive or Microsoft Onedrive, to software such as Quickbooks, Microsoft Office 365, to hosting and web support services such as Amazon AWS. Vendors benefit from converting one-time sales to recurring sales and increase customer loyalty. Customers benefit from the headache of installing updates, having the software support and updates taken care of automatically, knowing that the software continues to be updated with new features. A subscription model is now a prevalent option for both consumers and businesses.
Even if an organization determines to buy or subscribe, it still makes sense to go through many of the same analyses to compare the costs and benefits of building it themselves. This is an important decision that could have a long-term strategic impact on the organization.
Web Services
Chapter 3 stated that the move to cloud computing has allowed software to be looked at as a service. One option companies have these days to license functions provided by other companies instead of writing the code themselves. These are called web services, and they can greatly simplify the addition of functionality to a website.
For example, suppose a company wishes to provide a map showing the location of someone who has called their support line. By utilizing Google Maps API web services , they can build a Google Map right into their application. Or a shoe company could make it easier for its retailers to sell shoes online by providing a shoe-size web service that the retailers could embed right into their website.
Web services can blur the lines between “build vs. buy.” Companies can choose to build a software application themselves but then purchase functionality from vendors to supplement their system.
End-User Computing or Shadow IT
In many organizations, application development is not limited to the programmers and analysts in the information-technology department. Especially in larger organizations, other departments develop their own department-specific applications. The people who build these are not necessarily trained in programming or application development, but they tend to be adept with computers. A person, for example, who is skilled in a particular software package, such as a spreadsheet or database package, may be called upon to build smaller applications for use by his or her own department. This phenomenon is referred to as end-user development, or end-user computing, or shadow IT.
End-user computing can have many advantages for an organization. First, it brings the development of applications closer to those who will use them. Because IT departments are sometimes quite backlogged, it also provides a means to have software created more quickly. Many organizations encourage end-user computing to reduce the strain on the IT department.
End-user computing does have its disadvantages as well. If departments within an organization are
developing their own applications, the organization may end up with several applications that perform similar functions, which is inefficient since it duplicated effort. Sometimes, these different versions of the same application provide different results, bringing confusion when departments interact. These applications are often developed by someone with little or no formal training in programming. In these cases, the software developed can have problems that have to be resolved by the IT department. End-user computing can be beneficial to an organization, but it should be managed. The IT department should set guidelines and provide tools for the departments who want to create their own solutions.
Communication between departments will go a long way towards the successful use of end-user computing.
Sidebar: Building a Mobile App
Software development typically includes building applications to run on desktops, servers, or mainframes. However, the web's commercialization has created additional software development categories such as web design, content development, web server. Web-related development effort for the internet is now called web development. Earlier web development activities include building websites to support businesses or to build e-commerce systems and have made technologies such as HTML very popular with web designers and programming languages such as Perl, Python, Java popular for programmers. Pre-packaged websites are now available for consumers to purchase without learning HTML or hiring a web designer. For example, entrepreneurs who want to start a bakery business can now buy a pre-build website with a shopping cart, all ready to start a business without incurring costly expenses to build it themselves.
With the rise of mobile phones, a new type of software development called mobile app development came into being. Statista.com forecasts that Mobile apps revenues will increase significantly from $98B in 2014 to over $935B by 2023. This means that the need for mobile app developers has also increased.
In many ways, building an application for a mobile device is the same as building an application for a traditional computer. Understanding the application requirements, designing the interface, working with users – all of these steps still need to be carried out. The decision process to pick the right programming languages and tools remains the same.
However, there are specific differences that programmers must consider in building apps for mobile devices. They are:
- The user interface must vary to adapt to different screen size
- The use of fingers as pointers or to type in text instead of keyboard and mouse on the desktop
- Specific requirements from the OS vendor must be met for the app to be included in each store (i.e., Apple’s App Store or Android’s Play Store)
- The integration with the desktop or the cloud to synch up data
- Tight integration with other built-in hardware such as cameras, biometric or motion sensors.
- Less available memory, storage space, and processing power
Mobile apps are now available for just about everything and continue to grow.
References:
Javascript was the most used language among developers worldwide (2020). Retrieved December 10, 2020, from Satistica.com
Google Maps Platform Documentation . Retrieved December 10, 2020, from https://developers.google.com/maps/documentation
Programming/development tools used by software developers worldwide from 2018 and 2019 (2020) . Retrieved December 10, 2020, from S tatista.com
Worldwide mobile app revenues in 2014 to 2023 (2010.) Retrieved December 10, 2020, from Statista.com