Author Topic: What are the Non Functional Requirements  (Read 9388 times)

1171429110

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Re: What are the Non Functional Requirements
« Reply #15 on: December 07, 2017, 04:38:48 pm »
Basically, Non-functional requirements describe how the system works, while functional requirements describe what the system should do.
This does not mean the latter are more important, but most requirement gathering techniques focus on functional requirements, so large gaps in non-functional requirements are common.

Here are four examples of Non-Functional requirement. They are as follows

Usability
Prioritize the important functions of the system based on usage patterns. Frequently used functions should be tested for usability, as should complex and critical functions.

Reliability
Users have to trust the system, even after using it for a long time. Create a requirement that data created in the system will be retained for a number of years without the data being changed by the system. Make it easier to monitor system performance.

Security
Security is the degree of resistance to, or protection from, harm. Its important to have this feature as a requirement.

supportability
The system needs to be cost-effective to maintain.

VIJAY POGULA

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Re: What are the Non Functional Requirements
« Reply #16 on: December 09, 2017, 03:05:53 pm »
Non functional Requirements capture conditions that do not directly relate to the behavior or functionality of the solution, but rather describe environmental conditions under which the solution must remain effective or qualities that the system must have. They are also known as quality or supplementary requirements. These can include requirements related to capacity, speed, security, availability and the information architecture and presentation of the user interface.

1171625709

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Re: What are the Non Functional Requirements
« Reply #17 on: December 27, 2017, 12:24:30 pm »
Non-functional requirements
The definition of a non-functional requirement is:

Any requirement which specifies how the system performs a certain function.

In other words, a non-functional requirement will describe how a system should behave and what limits there are on its functionality.

Non-functional requirements generally specify the system’s quality attributes or characteristics, for example: “Modified data in a database should be updated for all users accessing it within 2 seconds.”

A non-functional requirement for the cup mentioned previously would be: “contain hot liquid without heating up to more than 45 °C”.

Typical non-functional requirements include:

Performance – for example: response time, throughput, utilization, static volumetric
Scalability
Capacity
Availability
Reliability
Recoverability
Maintainability
Serviceability
Security
Regulatory
Manageability
Environmental
Data Integrity
Usability
Interoperability
It is important to correctly state non-functional requirements since they’ll affect your users’ experience when interacting with the system.

One way to prevent missing out on important non-functional requirements is to use non-functional requirement groups as a guide for listing them down.

1171429410

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Re: What are the Non Functional Requirements
« Reply #18 on: January 01, 2018, 01:37:16 pm »
The Non functional requirements are there to support the functional requirements of the application. We can say they are indirectly present or present at the back end to support. These are scalability, speed, usability, security and capacity of the system developed. The non functional requirements can not be seen by the user at the front end of the application.
For example the home page must be displayed in 1 second.
« Last Edit: January 01, 2018, 01:39:39 pm by 1171429410 »

1171921109

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Re: What are the Non Functional Requirements
« Reply #19 on: January 21, 2018, 09:13:06 pm »
Some typical non-functional requirements are:

Performance – for example, Response Time, Throughput, Utilization, Static Volumetric
Scalability
Capacity
Availability
Reliability
Recoverability
Maintainability
Serviceability
Security
Regulatory
Manageability
Environmental
Data Integrity
Usability
Interoperability
As said above, non-functional requirements specify the system’s ‘quality characteristics’ or ‘quality attributes’.

Many different stakeholders have a vested interest in getting the non-functional requirements right particularly in the case of large systems where the buyer of the system is not necessarily also the user of the system.

1173025809

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Re: What are the Non Functional Requirements
« Reply #20 on: January 23, 2018, 02:25:18 pm »
In addition to the obvious features and functions that we will provide in our system, there are other requirements that don't actually do anything, but are important characteristics nevertheless, are called "Non-functional requirements" or sometimes "Quality Attributes."

For example, attributes such as performance, security, usability, compatibility are not a "feature" of the system, but are a required characteristic. We can't write a specific line of code to implement them, rather they are "emergent" properties that arise from the entire solution. The specification needs to describe any such attributes the customer requires. We must decide the kind of requirements that apply to our project and include those that are appropriate.

Here are some examples of non-functional requirements:

1. Performance requirements -
Requirements about resources required, response time, transaction rates, throughput, benchmark specifications or anything else having to do with performance.

2. Operating constraints -
List any run-time constraints. This could include system resources, people, needed software, ...

3. Platform constraints -
Discuss the target platform. Be as specific or general as the user requires. If the user doesn't care, there are still platform constraints.

4. Accuracy and Precision -
Requirements about the accuracy and precision of the data. (Do you know the difference?) Beware of 100% requirements; they often cost too much.

5. Modifiability -
Requirements about the effort required to make changes in the software. Often, the measurement is personnel effort (person- months).

6. Portability -
The effort required to move the software to a different target platform. The measurement is most commonly person-months or % of modules that need changing.

7. Reliability -
Requirements about how often the software fails. The measurement is often expressed in MTBF (mean time between failures). The definition of a failure must be clear. Also, don't confuse reliability with availability which is quite a different kind of requirement.  Be sure to specify the consequences of software failure, how to protect from failure, a strategy for error detection, and a strategy for correction.

8. Security -
One or more requirements about protection of your system and its data. The measurement can be expressed in a variety of ways (effort, skill level, time, ...) to break into the system.  Do not discuss solutions (e.g. passwords) in a requirements document.

9. Usability -
Requirements about how difficult it will be to learn and operate the system. The requirements are often expressed in learning time or similar metrics.

10. Legal -
There may be legal issues involving privacy of information, intellectual property rights, export of restricted technologies, etc.

1172540411

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Re: What are the Non Functional Requirements
« Reply #21 on: February 06, 2018, 07:12:13 pm »

NON FUNCTIONAL REQUIRMENTS

Software success cannot be achieved by simply delivering the right functionality. Users also have expectations, often unstated, about how well the product will work. Such expectations include how easy it is to use, how quickly it executes, how rarely it fails, how it handles unexpected conditions. Constitute a major portion of the system’s nonfunctional requirements.

Non functional Requirements describe the environment condition under which the solution must remain effective or qualities the system must have.

Quality attributes can distinguish a product that does what it’s supposed to from one that delights its users. Quality attributes serve as the origin of many functional requirements.

External quality attributes

External quality attributes describe characteristics that are observed when the software is executing.

Availability: Availability is a measure of the planned up time during which the system’s services are available for use and fully operational.

Installability.

Integrity: Integrity deals with preventing information loss and preserving the correctness of data entered into the system.

Interoperability: Interoperability indicates how readily the system can exchange data and services with other software systems and how easily it can integrate with external hardware devices.

Performance

Reliability: The probability of the software executing without failure for a specific period of time is known as reliability

Robustness: Robustness is the degree to which a system continues to function properly when confronted with invalid inputs, defects in connected software or hardware components, external attack, or unexpected operating  conditions.

Safety: Safety requirements deal with the need to prevent a system from doing any injury to people or  damage to property

Security: Security deals with blocking unauthorized access to system functions or data, ensuring that the software is protected from malware attacks, and so on.

Usability


Internal quality attributes

Internal quality attributes are not directly observable during execution of the software. They are properties that a developer or maintainer perceives while looking at the design or code to modify it, reuse it, or move it to another platform.

Efficiency: It is a measure of how well the system utilizes processor capacity, disk space, memory, or communication bandwidth.

Modifiability :Addresses how easily the software designs and code can be understood, changed, and extended.

Portability : The effort needed to migrate software from one operating environment to another is a measure of portability.

Reusability : Reusability indicates the relative effort required to convert a software component for use in other Applications

Scalability: Scalability requirements address the ability of the application to grow to accommodate more users, data, servers, geographic locations, transactions, network traffic, and other services without compromising performance or correctness.

Verifiability :Refers to how well software components or the integrated product can be evaluated to demonstrate whether the system functions as expected.

Two other classes of non functional  requirements are constraints and external interface requirements.

Constraints
A constraint places restrictions on the design or implementation choices available to the developer.

External interface requirements

User interfaces: Describe the logical characteristics of each user interface that the system needs.

Software interfaces: Describe the connections between this product and other software components, including other applications, databases, operating systems, tools, libraries, websites, and integrated commercial components.

Hardware interfaces: Describe the characteristics of each interface between the software components and hardware components,

Communications interfaces: State the requirements for any communication functions the product will use, including email, web browser, network protocols, and electronic forms.

1171948312

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Re: What are the Non Functional Requirements
« Reply #22 on: February 13, 2018, 06:26:48 pm »
Non-functional requirements are the one which are related to speed, capacity, performance, security etc., which will not effect the functionality of the application/system.

1170944412

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Re: What are the Non Functional Requirements
« Reply #23 on: March 10, 2018, 01:05:06 pm »
Non-functional requirements describe the conditions that do not directly relate to the behaviour or functionality of the solution. These are requirements that describe the environmental conditions under which the solution must remain effective, in other words the qualities the system must have to function efficiently. These requirements, typically are related to the capacity, speed, security, availability, the information architecture and presentation of user interface.

1170831310

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Re: What are the Non Functional Requirements
« Reply #24 on: March 13, 2018, 12:50:18 am »
In addition to the obvious features and functions that you will provide in your system, there are other requirements that don't actually DO anything, but are important characteristics nevertheless. These are called "non-functional requirements" or sometimes "Quality Attributes." 

Definition would be, "Any requirement that is not functional which cannot be categorized into Functional, Data or Process requirements."

For example, attributes such as performance, security, Reliability, usability, compatibility, aren't a "feature" of the system.
 

1172831810

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Re: What are the Non Functional Requirements
« Reply #25 on: April 07, 2018, 04:48:24 pm »
Basically, Non-functional requirements describe how the system works, while functional requirements describe what the system should do.

Here are four examples of Non-Functional requirement groups; usability, reliability, performance, and supportability, as well as a few top tips on each one.


Usability

Prioritize the important functions of the system based on usage patterns.
Frequently used functions should be tested for usability, as should complex and critical functions. Be sure to create a requirement for this.

Reliability

Users have to trust the system, even after using it for a long time.
Your goal should be a long MTBF (mean time between failures).
Create a requirement that data created in the system will be retained for a number of years without the data being changed by the system.
It’s a good idea to also include requirements that make it easier to monitor system performance.

Performance

What should system response times be, as measured from any point, under what circumstances?
Are there specific peak times when the load on the system will be unusually high?
Think of stress periods, for example, at the end of the month or in conjunction with payroll disbursement.

Supportability

The system needs to be cost-effective to maintain.
Maintainability requirements may cover diverse levels of documentation, such as system documentation, as well as test documentation, e.g. which test cases and test plans will accompany the system.

1172540611

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Re: What are the Non Functional Requirements
« Reply #26 on: April 29, 2018, 05:08:38 pm »
Non Functional requirements specify criteria that judge the operation of a system, rather than specific behaviors.

Some typical non-functional requirements are:

Performance – for example Response Time, Throughput, Utilization, Static Volumetric
Scalability
Capacity
Availability
Reliability
Recoverability
Maintainability
Serviceability
Security
Regulatory
Manageability
Environmental
Data Integrity
Usability
Interoperability

1182057301

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Re: What are the Non Functional Requirements
« Reply #27 on: May 19, 2018, 07:19:02 am »
 Nonfunctional Requirements (NFRs) define system attributes such as security, reliability, performance, maintainability, scalability, and usability. They do not directly relate to functionality of of the system but rather describe the condition under which the solution remains effective.

1180364703

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Re: What are the Non Functional Requirements
« Reply #28 on: June 01, 2018, 02:07:46 pm »
Non functional requirements are the requirements which are not directly related to the functionality of the system. The non-functional requirements can be classified as below:
Performance
Scalability
Supportability
Capacity
Availability
Reliability
Recoverability
Maintainability
Serviceability
Security

1172539811

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Re: What are the Non Functional Requirements
« Reply #29 on: June 03, 2018, 07:35:51 pm »
Non-functional requirements are the ones which support to achieve the functional requirements. Requirements other than the behavior like environmental conditions, functionality of the solution, quality through the measures of capacity, speed, security and etc.
 
Example: Turnaround time to process a payment though card. This describes the speed property.