computer science

Outside–in software development

Outside–in software development is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Outside–in software development rather than just read about it. In short: Of all the agile software development methodologies, outside–in software development takes a different approach to optimizing the software development process. Unlike other approaches, outside–in development focuses on satisfying the needs of stakeholders.

Key takeaways

Outside–in software development belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Outside–in software development to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Outside–in software development from memory before moving on to harder problems.

Reference excerpt

Of all the agile software development methodologies, outside–in software development takes a different approach to optimizing the software development process. Unlike other approaches, outside–in development focuses on satisfying the needs of stakeholders. The underlying theory is that to create successful software, the team must have a clear understanding of the goals and motivations of the stakeholders. The ultimate goal is to produce software that is highly consumable and meets or exceeds the needs of the intended client. Outside–in software development is meant to primarily supplement existing software development methodologies. While it is suited for agile software development, it is possible to fit outside-in development into waterfall-based methodologies.

The four stakeholder groups What sets outside-in software development apart from other stakeholder-based approaches is the categorization of the four types of stakeholders. While the following four groups are unique however there can be and is usually a lot of interaction between them:

Principals: The people who buy your software. This is the most important stakeholder group to appease. End users: The people who interact with your product. They experience how your software works in the real world. Partners: The people who make your product work in real life, such as operations teams and also business partners and system integrators. Insiders: The people within your company that have some impact on how your team develops software. It is crucial to speak with all stakeholders, even if they are not the primary audience of your software.

Implementing outside–in software development The outside–in approach does not require your entire development methodology to change. Outside–in development can supplement the existing tools of developers. Outside–in development works particularly well in the context of agile/lean development. One of the major tenets of lean-based software development is to program with the least amount of waste. Outside-in methodologies promote only developing according to stakeholder requirements. By identifying your stakeholders properly and soliciting helpful feedback early on in the development process, agile and outside-in methodologies can mesh together seamlessly. Kessler and Sweitzer recommend that, no matter what kind of development methodology you employ, you incrementally introduce outside–in development to your team. They cite the lack of enthusiasm by developers as the main reason to not implement sweeping, large scale change. Outside–in software development should not be introduced as a holistic development process. It is meant to supplement your current software development methodology.

See also Software development process Software engineering Extreme programming Agile software development Waterfall model Six Sigma

References Carl Kessler and John Sweitzer. Outside-in Software Development: A Practical Approach to Building Successful Stakeholder-based Products, IBM Press. First Edition, 2008. ISBN 0-13-157551-1. Pp. 1–3, 23–31, 183–195 Craig Larman and Victor R. Basili. Iterative and Incremental Development:A Brief History IEEE Computer, June 2003

Worked examples

Example 1 — a first encounter with Outside–in software development

Start with the simplest possible case. Write down what Outside–in software development claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Outside–in software development before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Outside–in software development ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Outside–in software development

In research: Outside–in software development appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Outside–in software development in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Outside–in software development is common in secondary-school and first-year university syllabi. It links to neighbouring topics Human–computer interaction, Software development process, so understanding it makes those chapters shorter.
In everyday life: Look for Outside–in software development outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Outside–in software development in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Outside–in software development means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Outside–in software development out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Outside–in software development in simple terms?

Why does Outside–in software development matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Outside–in software development?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Outside–in software development.