Software architecture rules and effects

“Complexity increases the possibility of failure; a twin-engine airplane has twice as many engine problems as a single-engine airplane”

“Adding manpower to a late software project makes it later”

“Any organization that designs a system (defined broadly) will produce a design whose structure is a copy of the organization’s communication structure”; or by Eric S. Raymond “If you have four groups working on a compiler, you’ll get a 4-pass compiler”

principle of imperative computer programming stating that every method should either be a command that performs an action, or a query that returns data to the caller, but not both.

principle of software development aimed at reducing repetition of software patterns, replacing it with abstractions or using data normalization to avoid redundancy.

“Anything that can go wrong, will—at the worst possible moment”

“The truly insane have enough on their plates without us adding to it”

“As a Usenet discussion grows longer, the probability of a comparison involving Nazis or Hitler approaches one”

“Any sufficiently complicated C or Fortran program contains an ad hoc, informally-specified, bug-ridden, slow implementation of half of Common Lisp.”

“It always takes longer than you expect, even when you take into account Hofstadter’s Law”

“With a sufficient number of users of an API, it does not matter what you promise in the contract: all observable behaviors of your system will be depended on by somebody.”

most systems work best if they are kept simple rather than made complicated; therefore, simplicity should be a key goal in design, and unnecessary complexity should be avoided

”I suppose it is tempting, if the only tool you have is a hammer, to treat everything as if it were a nail.”

8 laws labelled {Continuing Change, Increasing Complexity, Self Regulation, Conservation of Organisational Stability, Conservation of Familiarity, Continuing Growth, Declining Quality, Feedback System}

“Mortality rate of technology decreases with time”

“the number of transistors in a dense integrated circuit (IC) doubles about every two years”

“The first 90 percent of the code accounts for the first 90 percent of the development time. The remaining 10 percent of the code accounts for the other 90 percent of the development time”

“work expands so as to fill the time available for its completion” or (… law for Data) “Data expands to fill the space available for storage”

“be conservative in what you do, be liberal in what you accept from others”

the tendency of small, elegant, and successful systems to be succeeded by over-engineered, bloated systems, due to inflated expectations and overconfidence

practice of structuring information models and associated data schema such that every data element is mastered (or edited) in only one place

“A piece of program code, not yet written, whose anticipated length is significantly greater than its intellectual complexity”. It often implies that the person proposing the feature underestimates its cost.

describes a dying project which has become too complex to be understood even by its own developers

“ninety percent of everything is crap”

“[when] we reduce the complexity people experience in a given task, people will take on a more challenging task” (Bruce Tognazzini). It is “an observation that products aiming to simplify a task for users tend to inspire new, more complex tasks. It’s one of the key reasons for the symptom of requirements changing after delivery in enterprise software products, and for feature creep in consumer products”

any programming language or computer interface that allows for flexibility in function but is difficult to learn and use because it offers little or no support for common tasks (“Beware of the Turing tar-pit in which everything is possible but nothing of interest is easy”)

“software is getting slower more rapidly than hardware is becoming faster”

“Every program attempts to expand until it can read mail. Those programs which cannot so expand are replaced by ones which can.”

“Allow none of foo, one of foo, or any number of foo” ⇒ “The only reasonable numbers are zero, one and infinity.”

“Each unit should have only limited knowledge about other units. Each unit should only talk to its friends; don’t talk to strangers.”