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Category Archives: Design Issues
The Baker’s Dozen of Use Cases
Technical Consultant at Feabhas Ltd
Glennan is an embedded systems and software engineer with over 20 years experience, mostly in high-integrity systems for the defence and aerospace industry.
He specialises in C++, UML, software modelling, Systems Engineering and process development.
He specialises in C++, UML, software modelling, Systems Engineering and process development.
Latest posts by Glennan Carnie (see all)
- Practice makes perfect, part 3 – Idiomatic kata - February 27, 2020
- Practice makes perfect, part 2– foundation kata - February 13, 2020
- Practice makes perfect, part 1 – Code kata - January 30, 2020
RULE 7: Describe ALL the transactions
A use case, as the name implies, describes the usage of the system from the point of view of some beneficiary (our Actor). It is NOT (as I seem to spend my whole life telling people) is just the system function, organised as some sort of graphical ‘sub-routine’. This means the use case description must include the expected behaviour of the actors as well as the expected behaviour of the system.
This can […]
Posted in Design Issues
Tagged Analysis, Baker's Dozen, Requirements, Transaction, UML, Use Cases
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The Baker’s Dozen of Use Cases
Technical Consultant at Feabhas Ltd
Glennan is an embedded systems and software engineer with over 20 years experience, mostly in high-integrity systems for the defence and aerospace industry.
He specialises in C++, UML, software modelling, Systems Engineering and process development.
He specialises in C++, UML, software modelling, Systems Engineering and process development.
Latest posts by Glennan Carnie (see all)
- Practice makes perfect, part 3 – Idiomatic kata - February 27, 2020
- Practice makes perfect, part 2– foundation kata - February 13, 2020
- Practice makes perfect, part 1 – Code kata - January 30, 2020
RULE 6: If it’s not on the Context or Domain models, you can’t talk about it
(If you haven’t already read it, I’d suggest having a quick look over Part 1 of the Baker’s Dozen to familiarise yourself with the fundamentals of use case descriptions.)
Engineers love to solve problems. It’s what they do. A use case model though is not a design model – it’s an analysis model. Use cases describe what the system should do, and in […]
The Baker’s Dozen of Use Cases
Technical Consultant at Feabhas Ltd
Glennan is an embedded systems and software engineer with over 20 years experience, mostly in high-integrity systems for the defence and aerospace industry.
He specialises in C++, UML, software modelling, Systems Engineering and process development.
He specialises in C++, UML, software modelling, Systems Engineering and process development.
Latest posts by Glennan Carnie (see all)
- Practice makes perfect, part 3 – Idiomatic kata - February 27, 2020
- Practice makes perfect, part 2– foundation kata - February 13, 2020
- Practice makes perfect, part 1 – Code kata - January 30, 2020
RULE 5: Focus on goals, not behaviour
There is a subtle distinction between the functional behaviour of the system and the goals of the actors. This can cause confusion: after all, the functional behaviour of the system must surely be the goal of the actor?
It is very common, then, for engineers to write use cases that define, and then describe, all the functions of the system. It is very tempting to simply re-organise the software requirements into functional areas, each […]
Posted in Design Issues, UML
Tagged Analysis, Baker's Dozen, Design Case, Goals, Requirements, Use Case
1 Comment
The Baker’s Dozen of Use Cases
Technical Consultant at Feabhas Ltd
Glennan is an embedded systems and software engineer with over 20 years experience, mostly in high-integrity systems for the defence and aerospace industry.
He specialises in C++, UML, software modelling, Systems Engineering and process development.
He specialises in C++, UML, software modelling, Systems Engineering and process development.
Latest posts by Glennan Carnie (see all)
- Practice makes perfect, part 3 – Idiomatic kata - February 27, 2020
- Practice makes perfect, part 2– foundation kata - February 13, 2020
- Practice makes perfect, part 1 – Code kata - January 30, 2020
RULE 4 : The “Famous Five” of requirements modelling
As I discussed in Rule 1, a common misunderstanding of use cases is that they are the software requirements. Unfortunately, this isn’t the situation. Use cases are merely an analysis tool – albeit a very powerful tool (when used in the right situation).
Use cases are just one technique for understanding and analysing the requirements. In order to fully understand the requirements our use cases are going to need some […]
Posted in Design Issues, General, UML
Tagged Behaviour, Context, Context Model, Domain, Domain model, Modes model, State Machine, SysML, UML, Use Case
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The Baker’s Dozen of Use Cases
Technical Consultant at Feabhas Ltd
Glennan is an embedded systems and software engineer with over 20 years experience, mostly in high-integrity systems for the defence and aerospace industry.
He specialises in C++, UML, software modelling, Systems Engineering and process development.
He specialises in C++, UML, software modelling, Systems Engineering and process development.
Latest posts by Glennan Carnie (see all)
- Practice makes perfect, part 3 – Idiomatic kata - February 27, 2020
- Practice makes perfect, part 2– foundation kata - February 13, 2020
- Practice makes perfect, part 1 – Code kata - January 30, 2020
RULE 3: Never mix your Actors
The UML definition of an Actor is an external entity that interacts with the system under development. In other words: it’s a stakeholder.
Having analysed all your stakeholders (see Part 3 ) it’s tempting to stick them (no pun intended) as actors on a use case diagram and start defining use cases for each.
Each set of stakeholders (Users, Beneficiaries or Constrainers) has its own set of concerns, language and concepts:
Concerns.
Each stakeholder group has a different […]
Posted in Design Issues, UML
Tagged Analysis, Baker's Dozen, Requirements, UML, Use Cases
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The Baker’s Dozen of Use Cases
Technical Consultant at Feabhas Ltd
Glennan is an embedded systems and software engineer with over 20 years experience, mostly in high-integrity systems for the defence and aerospace industry.
He specialises in C++, UML, software modelling, Systems Engineering and process development.
He specialises in C++, UML, software modelling, Systems Engineering and process development.
Latest posts by Glennan Carnie (see all)
- Practice makes perfect, part 3 – Idiomatic kata - February 27, 2020
- Practice makes perfect, part 2– foundation kata - February 13, 2020
- Practice makes perfect, part 1 – Code kata - January 30, 2020
RULE 2: Understand your stakeholders
A Stakeholder is a person, or group of people, with a vested interest in your system. Vested means they want something out of it – a return on their investment. That may be money; it may be an easier life.
One of the keys to requirements analysis is understanding your stakeholders – who they are, what they are responsible for, why they want to use your system and how it will benefit them.
It’s important to […]
Posted in Design Issues, UML
Tagged Analysis, Baker's Dozen, Requirements, Stakeholder, UML, Use Cases
1 Comment
The Baker’s Dozen Of Use Cases
Technical Consultant at Feabhas Ltd
Glennan is an embedded systems and software engineer with over 20 years experience, mostly in high-integrity systems for the defence and aerospace industry.
He specialises in C++, UML, software modelling, Systems Engineering and process development.
He specialises in C++, UML, software modelling, Systems Engineering and process development.
Latest posts by Glennan Carnie (see all)
- Practice makes perfect, part 3 – Idiomatic kata - February 27, 2020
- Practice makes perfect, part 2– foundation kata - February 13, 2020
- Practice makes perfect, part 1 – Code kata - January 30, 2020
RULE 1: Use Cases Aren’t Silver Bullets
There are a couple of popular misconceptions around use cases:
Misconception 1: The use cases are the requirements of the system
Contrary to what many engineers believe (and many authors have written) the complete set of use cases do NOT constitute its full set of requirements for the system.
A use case model is an analysis tool. They are a mechanism for organising the functional behaviour of the system and reflecting it back to the […]
A Brief Introduction to Use Cases
Technical Consultant at Feabhas Ltd
Glennan is an embedded systems and software engineer with over 20 years experience, mostly in high-integrity systems for the defence and aerospace industry.
He specialises in C++, UML, software modelling, Systems Engineering and process development.
He specialises in C++, UML, software modelling, Systems Engineering and process development.
Latest posts by Glennan Carnie (see all)
- Practice makes perfect, part 3 – Idiomatic kata - February 27, 2020
- Practice makes perfect, part 2– foundation kata - February 13, 2020
- Practice makes perfect, part 1 – Code kata - January 30, 2020
Since Jacobson defined use cases back in 1992 they have been subject to a vast range of interpretations. Alistair Cockburn, author of Writing Effective Use Cases states:
“I have personally encountered over 18 different definitions of use case, given by different, each expert, teachers and consultants”
I am no different: this is my personal interpretation of use case modelling and analysis. To qualify this statement though, this methodology is based on nearly a decade of requirements definition work on a number high integrity projects, […]
Elizabethan guidance on Object-Oriented software design
Technical Consultant at Feabhas Ltd
Glennan is an embedded systems and software engineer with over 20 years experience, mostly in high-integrity systems for the defence and aerospace industry.
He specialises in C++, UML, software modelling, Systems Engineering and process development.
He specialises in C++, UML, software modelling, Systems Engineering and process development.
Latest posts by Glennan Carnie (see all)
- Practice makes perfect, part 3 – Idiomatic kata - February 27, 2020
- Practice makes perfect, part 2– foundation kata - February 13, 2020
- Practice makes perfect, part 1 – Code kata - January 30, 2020
So what did the Elizabethans know about software development? Well, in truth, nothing whatsoever. But what they had begun to do is codify and systematise the knowledge and experience of masters in manuals, treatises and books. Some of the earliest documents of this form refer to the martial arts or, as it was known at the time the ‘Arts of Defence’
In martial arts one learns practical skills (in this case how to defend oneself against any enemy) through practice and […]
Posted in Design Issues
Tagged abstraction, cohesion, coupling, design, encapsulation, quality
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The Psychology of Everyday Things
Director at Feabhas Limited
Co-Founder and Director of Feabhas since 1995.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.
Latest posts by Niall Cooling (see all)
- Navigating Memory in C++: A Guide to Using std::uintptr_t for Address Handling - February 22, 2024
- Embedded Expertise: Beyond Fixed-Size Integers; Exploring Fast and Least Types - January 15, 2024
- Disassembling a Cortex-M raw binary file with Ghidra - December 20, 2022
On my recent trip to e mbedded world in Nuremberg, the lift (elevator) system in the hotel only had a single button to call the lift car.
This caused various problems as there was no ability to select direction of travel. My room wasn’t on the top floor, so when the doors opened I had no idea whether I was going to take a trip to a higher floor even though I wanted to go down […]
Posted in Design Issues
Tagged donald norman, embedded world, poor design, psychology of everyday things
3 Comments