What is the difference between Requirements Specification document and Design document??

Question

and what are the methods of extracting integration test scenarios from both documents ?

Answer 1

Requirements spefications state what needs to be done by a system. It specifies what day to day, monthly yearly, ... tasks need to be performed by the system. It also specifies the requirements of up-time, maximum down-time allowances, costs associated with down times, etc.

In the system requirments, some functions do not include automation. Sometimes automation is not moving forward based on the requirements. For example, a law office may not want telephone calls to automatically go to voice mail. The office may want the phone answered manually, with the receptionist writing the message on a post-it note. The secretary may also enter the message in an email to the appropriate person, but that is part of the system requirements specification.

The requirements specification states what needs to be done in order for the organization to fulfill their purpose.

The design specification is an educated recommendation on the best way to perform all of the tasks required. Some of the recomendations may or may not include computers. The use of computers in the design specification is as much as it is not relavent.

There are many tasks that can be automated with the use of computers. Many of these tasks can be simplified by linking to other computers or computerized systems. The tasks that can be automated with computer systems have to have the costs of automation justified against the costs of doing those tasks manuually. For example, you may not want to have your business pay $1000 a month for an automated service or software that can be done manually for $25 a month.

The design specification is the blueprints of how the business requirements meld with the business budget. It considers the business budget in the design. A $2,500 pen may be the best way to sign a contract, but it may not be the best fit for the needs of the business.

On the other hand, if a $35,000 software investment can save $75,000 a year, while providing better access to information to key sales persons, that should be included in the design.

What it all boils down to is this. The functions in the requirements specifications that can be automated to save money or increase revenues, should be automated. The functions that should be un-automated to reduce costs or increase revenues, should be un-automated.

Answer 2

Design criteria: Support cable must be able to safely hold the 1000 lb load. Specification: Published tensile strength is 2000 lbs (1000 lbs with a safety factor of 2). Design criteria: The unit must be able to fit through the laborotory door, which is 3 feet wide. Specification: Maximum width is 3 feet. The design criteria is the underlying requirement that determines the specification. Design criteria is typically a verbal justification where a specification is typically numerical.

Answer 3

Requirements is what the user wants
Design is what the user is going to get.

Integration test is the joining of parts. So the tests will be a complete process from start to finish. Not just the testing of one window.
For a banking application with an ATM it would be make card transaction.

Card in machine , make withdrawal, check results. etc.