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Software requirements specification in the real world – The good, the bad & the ugly. Why do we need software requirements specification, where does it go wrong (samples), who can do it?
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Software requirements specification in the real world – The good, the bad & the ugly
By Tobias Andersen
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• A Software Requirements Specification (SRS) is a complete description of the behavior of the system to be developed.
• It includes a set of use cases that describe all the interactions the users will have with the software.
• In addition to use cases, the SRS also contains nonfunctional (or supplementary) requirements. Non-functional requirements are requirements which impose constraints on the design or implementation (such as performance engineering requirements, quality standards, or design constraints).
Definition according to wikipedia...
Why do we need a SRS...
Why?
At a glance...Where REQUIREMENTS can help
What often happens...Ba
d Re
quire
men
ts
Bad
Assi
gnm
ent
You cannot build what you do not understand
No amount of SPIN can replace a quality product
Starting off wrong, leads to a short lifeBa
d Re
quire
men
ts
Bad
Exec
ution
Bad
Valu
e
Bad
Long
evity
Bad Input leads to Bad outputBa
d Re
quire
men
ts
So what is a better way?
The SRS lifecycle
Its not a science
Can I do it?
The Good (Case 1)
• Project brief: Substitute X resource with Y resource on the clients corporate website. UX have created a ”resource map”, which is located on our internal project server.
• Projected duration: 1 business day.
• Estimated rate of success: >75%.
The Good (case 1) it was a piece of cake.
• Technical brief: Substitute X resource with Y resource on the clients corporate website at ftp://mysite.com.
See sitemap from UX @ \\{server}\{project} for further details on the resource-2-page mappings.
• Actual development time: 1½ business day.
• Actual rate of success: 100%.
The BAD (case 2)
• Project brief: Substitute X resource with the document we uploaded last month to our clients corporate website.
• Projected duration: ½ - 1 business day.
• Estimated rate of success: 75% <> 50%.
The Bad (case 2) we got lucky...
• Technical brief: Substitute X resource with its predecessor (unknown document, ask Claus he worked on it a month ago) on the clients corporate website at ftp://mysite.com.
See sitemap from UX @ \\{server}\{project} for further details on the resource-2-page mappings.
• Actual development time: ½ business day.
• Actual rate of success: 50%.
The UGLY (case 3) it’s not a science, it’s black magic
• Project brief: Hi Tobias. ”Your account manager asked me to forward you this email discussion that describes our change requests. If you have any questions feel free to contact me (p.s: I might be busy, but leave a message and I will get back to you ASAP.). Have a nice day! ”
• Projected duration: ? business day.
• Estimated rate of success: <25%.
The Ugly (case 3) not even the Beauty could love this Beast
• Technical brief: Read this email thread and do the needful!
• Actual development time: Just bill the client by the hour. Job nr. is 00911.
• Actual rate of success: 0%.
What have we learned
• A well-crafted SRS document mitigates risk.• SRS does not have to be 50 page documents.
It can be something as simple as a set of use cases defining the clients needs.
How to convert the Ugly into the Good
• When in doubt ask your client. If they don’t know, chances are you don’t need to know.
• Express your needs in a form that a 5 year old could understand!
Good Input enables Beautiful output