2 Process & Requirements , Architecture Evaluation , Quality attribute scenarios

A business driver is a resource, process or condition that is vital for the continued success and growth of a business.

• Maintainability.
• Example: A car system should be able to not have any software failures for at least two years since deployment.

Functional requirement of a booking system; The system shall be able to provide the user with all the available tickets that are ready for booking.

• Fully completing the architecture before building the project will not work as well with more iterative and agile styles of development as they don't allow they developers enough flexibility to let the arch evolve with the system, this is the trade-off that has to be balanced.
• To solve this one can initially decide on a arch vision to guide decisions but let the real architectural decisions evolve with each iteration.

• For remote teams it critical to have a good software architecture as this will both align the teams vision of the project and their understanding of who will do what and in what way it will be done and why.
• Without a good software architecture miscommunication that could cost the project both time and money is much more likely.

• Source:
• External attacker

• Stimulus:
• Wants to display users confidential info

• Artifact:
• System data

• Environment:
• Normal operation

• Response:
• Attacker fails as system require 2fa that he cant get correct, account is locked, real user user is notified via email.

Response Measure: No account info is leaked and the real user is notified via email.

• Source:
• End user

• Stimulus:
• User wants to calculate tax

• Artifact:
• System , calculator

• Environment:
• Normal usage

• Response:
• System calculates return based on previously imputed data.

Response Measure: Calculation should not take longer then 2 seconds 99.9% of the calculations.

Source: Tax return system

• Stimulus:
• Wants to confirm a customer bank account

• Artifact:
• Nordea Bank System

• Environment:
• Other system known prior

• Response:
• Tax return system sends nordea user account info and expects account info in return

• Response Measure:
• Should not fail more than 99.9% of the time.

• Source:
• Developer

• Stimulus:
• Update formula for tax return

• Artifact:
• Platform

• Environment:
• Build time

• Response: Locates places in architecture to be modified;
• makes modification without affecting other functionality;
• tests modification;
• deploys modification.

Response Measure: Website calculation formula and rest of website works as intended.

Source of stimulus. This is some entity (a human, a computer system, or any other actuator) that generated the stimulus.

Stimulus. The stimulus is a condition that needs to be considered when it arrives at a system.

Environment. The stimulus occurs within certain conditions. The system may be in an overload condition or may be running when the stimulus occurs, or some other condition may be true.

Artifact. Some artifact is stimulated. This may be the whole system or some pieces of it.

Response. The response is the activity undertaken after the arrival of the stimulus.

Response measure. When the response occurs, it should be measurable in some fashion so that the requirement can be tested.

To make sure the system satisfies the stakeholders needs.Are we building the right things using good solutions and do we have the resources to implement the architecture?

To validate the systems resuability and maintainability. This can be evaluated to know for sure if it system satisfies the standards set for the project. 


An early overall evaluation of the architecture could allow us to find flaws in the architecture which would save time and money though not building the right things the right way and discover this at a later point and from there have to re-do.

Everyone is going to say the system must be secure — whatever that means.

Qa´s solved this by specifying what secure means with a clear example an how we can measure the systems effectiveness in achieving the quality standard.

Source of Stimulus: An entity capable of creating stimulus (internal or external people, a computer system, etc).


Stimulus: What is the source doing that will let us this this attribute´s fulfillment?

Environment: The environment where the stimulus occurs. For instance, the system may be running in normal conditions, under heavy traffic, or with a high latency or any relevant state.

Artifact: The part that receives the stimulus. This can be a component of the system, the whole system, or several systems.

Response: The is the response of the artifact that makes sure we fulfill the quality in question for this scenario.

Response Measure: This is the measure that should be tested for the response to test if the requirement is well implemented.