Showing posts from September, 2013

From the Editors: Charge of the Light Brigade

[Originally published in the January/February 2008 issue (Volume 6 number 1) of IEEE Security & Privacy magazine.] In 1970, the late Per Brinch Hansen wrote a seminal article ( "The Nucleus of a Multiprogramming System" ) that articulated and justified what today we call policy/mechanism separation. He introduced the concept in the context of an operating system's design at a time when experts felt we lacked a clear understanding of what the ultimate shape of operating systems would be. The concept, like other powerful memes, was so compelling that it took on a life of its own and is now an article of faith in CS education—taught without reference to the original context. The idea isn't original to computer science—it has existed for thousands of years. In martial terms, it's reflected in the popular paraphrase from Alfred, Lord Tennyson 's poem, Charge of the Light Brigade : "ours is not to reason why; ours is but to do and die." Separation of